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Essay Abstract

Intended to offer a fresh look at a venerable chestnut of speculation, the essay describes why time travel of the variety portrayed in science fiction is not possible, and, in so doing, offers thoughts about time which are intended to shed light on its fundamental nature.

Author Bio

J. C. N. Smith is retired from the CIA's former Office of Scientific and Weapons Research. Reading, thinking, and occasionally writing about issues related to time have been his avocation and passion for more than 40 years, with specific aims being to gain a deeper understanding of the universe and its workings and to peel away misperceptions which may be impeding advances in modern physics. He has published several monographs on the nature of time.

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A very interesting and clear written essay and I like it very much (though i cannot agree to every conclusion within it).

The notion of time as changing configurations of matter is intuitive. The question for me is, can all the possible configurations exist "simultaneous" with the help of quantum mechanical superpositions? This would be the case if some concepts of the multiverse would be true. Nonetheless in such a multiverse - i only guess - the most universes would have their own "flow of time". So why need changes in the configuration of matter *time* at all? This is a somewhat stupid but interesting question for me, because the notion of "changes" implies "time" and the question is: Why can - or *must* - there exist such things like "changes" at all (and are "changes" a relative or an absolute property of all_that_exists)?

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Thank you for your comments. Have you read Julian Barbour's book 'The End of Time'? If not, I highly recommend it. He addresses issues relevant to those you've raised. Definitely worth exploring.

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Thanks also for your book reference. I read Julian's essay on the nature of time contest and it's a really great pleasure to read, contemplate and enjoy his findings. I also saw the interview of him with Graig Callender at blogginheads.tv.

Barbours thoughts inspired my own thinking about certain issues that encircle my questions and possible answers to this questions. I will try to get *End of time* in the next weeks, i didn't read it yet, but the table of contents looks exciting and with high probability holds what his essay on fqxi promises. Though i also cannot agree to every conclusion Julian Barbour made in his video interview, i feel that it is a must to read his point of view properly.

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I have to say you have got a very nice essay and I agree with you that there is no time travel. However, your argument is incomplete in the following sense: in general relativity space-time can be bended back to itself, and while in every point the local causality still applies, globally it may not. Back to your argument, the calcium atom in the dinosaur can exist both in the dinosaur and in the time traveler's tooth at the same time. As long at the time traveler ultimately returns to its own time and there are no paradoxes created by this peculiar state of affairs, all is OK. For another argument against time travel and other references for and against time travel, please see my paper: http://arxiv.org/abs/0704.3074

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In his book 'The Trouble With Physics,' Lee Smolin wrote, "More and more, I have the feeling that quantum theory and general relativity are both deeply wrong about the nature of time. It is not enough to combine them. There is a deeper problem, perhaps going back to the origin of physics." (page 256) This is precisely the point which I make, explicitly, in reference 4 to my current essay. See http://googlepages.com/time . This is why I believe we must question the validity of notions such as "space-time bending back on itself." That may be true IF you accept the conventional concept of time, but it is exactly this conventional concept which I believe we must re-examine and re-think.

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I am not convinced Smolin is entirely right in his assessment. For quantum mechanics, I do not think there is anything wrong or incomplete with it. For general relativity, in the classical domain the theory cannot answer the deep foundational questions because we need quantum gravity for that. I agree we need a better fundamental understanding of the concept of time and here Smolin is right: the answer seats at the foundation of physics. I think I have a good answer for that in my essay: “Heuristic rule for constructing physics axiomatization“. Please feel free to comment on my interpretation.

About the time space bending back on itself, those are exact solutions of general relativity which are possible because the general relativity equations are local equations. Because they are so many of those solutions, they cannot be simply brushed aside. The (yet unsolved) quantum gravity challenge is to explain why those solutions will never occur in the real world. Hawking offered a partial answer to this, but the issue is still not decided.

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Mr. Smith, how can your assertion be falsified? If it cannot be falsified then can it be 'scientific' and, if not, physics? Thank you.

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Mr. Huffman,

Thank you for your comment! You raise a good point! And I have what I believe is a good reply to the point you raise. There is more to my proposed definition of a particular time than first meets the eye. Although I did not think it was appropriate to address all the ramifications of the proposed definition in this essay, I did address some of them in reference 4 to the essay. The proposed definition leads directly to logical conclusions which do lend themselves to falsification! Please see http://smithjcn.googlepages.com/time Thank you!

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So your essay here is incomplete or does not lead to logical conclusions?

How are we to evaluate the essay if it is incomplete? In the logical extreme we would have read each author's entire oeuvre.

It is not my intention to be argumentative. Thank you for addressing my peculiar concern with falsification.

Doug Huffman

Washington Island

Wisconsin

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The theme of the current essay cmpetition concerns what is or is not possible in physics. The additional information to be found in my referenced essay does not bear directly on this theme, and hence I chose not to address it here. You could be correct to question the wisdom of that decision.

Of course another obvious way to falsify the assertion of my current essay would be to demonstrate that someone has in fact accomplished time travel of the variety portrayed in science fiction! Thanks again for your comments.

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I enjoyed the essay & basically agree with the premise that what we call "time" can only make sense in the context of relative configurations & motion. However, I think that for a complete alternative description, we need to specify what it is that allows or facilitates this motion/change. Unless we invoke Julian Barbour's "timeless" world, denying real motion altogether in favour of static configurations which transform under a "principal of least action" & described by a static/time independent wave function, then we must define the dimensional structure? in which motion takes place.

This is motivated also by the fact that it does not seem possible to fully describe the world in just 3 dimensions, that is, an "event" cannot be completely defined with just 3 (spacial) numbers. In your scenario the 4th "number" would relate to the particular unique configuration corresponding to some specified date/period. One reason why I see this as incomplete is due to Relativity, where there is no "special" or "preferred" frame of reference for the configuration to be specified in! (think of the "twin paradox"). This time dilation effect due to relative velocities for instance allows for the "future" to, in a sense, be observed/accessed without causal violation & taken to it's maximal conclusion (ie the speed of light), in principal allows for the whole future of the Universe to be observed.

Linking the dimensional structure with these Relativistic effects shows that any object has in a sense an "extended existence" potentially through all inertial frames of reference.

Quickly summing up, I feel that a more realistic description of what we perceive as time, might involve a kind of "velocity space" wherein all events exist.

Any thoughts on this please? Thanks again for the interesting essay.

Roy J.

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Mr. Johnstone,

Thank you for your comments, which certainly are on target. I'm currently about three quarters through the process of very carefully re-reading Barbour's 'The End of Time,' and would like to withhold a direct reply to your points until I've completed this review. My views of time are something on the order of 98 percent aligned with Barbour's on most issues, but I am yet to be convinced of his claim that the universe is static. His description of what he calls the Machian distinguished simplifier in Chapter 7 seems to offer a way to explain dynamic phenomena without recourse to the notions of absolute space and time. This hope later appears to be dashed, however, in Chapter 17.

One very quick comment on your observations regarding relativity: Barbour correctly points out (on page 137 of The End of Time) that, "Relativity is not about an abstract concept of time at all: it is about physical devices called clocks. Once we grasp that, many difficulties fall away."

If you like the approach taken in my current essay, I'd urge you to read my reference 4, which offers a slightly different approach to the broader topic of time. As noted elsewhere in these posts, that essay does not address any implications for time travel, per se, so in the interest of staying on topic for this competition, I did not allude to some of the interesting (to me at any rate) ramifications of this approach to time which are addressed there.

I'll try to offer a better response to your comments after completing my review of The End of Time.

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Mr. Johnstone,

Having now finally completed my re-reading of Julian Barbour's 'The End of Time,' (TEOT) I will do my best to comment on the excellent points you raised.

As noted in my previous post, my thinking is closely aligned with Barbour's on many points. Where I part company with his thinking is on the major and crucial subject of motion. He argues that the universe is...

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Mr. Johnstone,

Having now finally completed my re-reading of Julian Barbour's 'The End of Time,' (TEOT) I will do my best to comment on the excellent points you raised.

As noted in my previous post, my thinking is closely aligned with Barbour's on many points. Where I part company with his thinking is on the major and crucial subject of motion. He argues that the universe is static. I maintain that motion is real. Which brings us to the point you raised: how can we describe motion in a three-dimensional universe without recourse to some additional dimension? I believe that Barbour offers a path to accomplishing this in his Chapter 7, in which he describes his collaboration with Bruno Bertotti to lay out a genuine Machian theory of the universe.

If there is motion, as I maintain, then how do we describe the 'trajectory' of the universe from one configuration to another without recourse to an absolute time and space? On page 120 of TEOT, in describing what he has called the "Machian distinguished simplifier," Barbour writes, "When this distinguished simplifier is used as 'time', it turns out that each object in the universe moves in the Machian framework described above exactly as Newton's laws prescribe. Newton's laws and his framework both arise from a single law of the universe that does not presuppose them. In such a universe, the ultimate standard of time that determines which curve is traced by Galileo's ball when it falls off his table in Padua is unambiguous. It is the average of all the changes in the universe that defines the Machian distinguished simplifier. Time is change, nothing more, nothing less." The goal, as I see it, is to have a dynamics which describes how the three-dimensional universe moves from one configuration to another without requiring the a separate dimension for time.

Barbour writes (p. 69), "Of course, to say that time has passed, we must have some evidence for that. Something must move. That is the most primitive fact of all." Of course, I fully concur with that view. But I do not take the point for granted. Another "primitive" fact which misled us for centuries was the apparent rising and setting of the sun; this, like the concept of motion, was something we could literally see with our own eyes. And yet it was fooling us into holding a faulty perception of the universe. Could our perception of motion be simply another trick of nature? Perhaps, but I do not think so. We corrected our faulty perception of what it meant to observe the sun apparently rising and setting when we obtained more information and a better perspective in the form of empirical, astronomical observations. I do not foresee that happening with our perception of the reality of motion.

As to the point you raise about the "twins paradox," I would simply reiterate my previous comment, echoing Barbour, that relativity deals with the behavior of mechanical devices which we call clocks. I concur totally with his comment (page 107) that ". . . there is only one ultimate clock: the universe." The twins must be put into this larger perspective to see what happens with them and with their clocks, relative to the bigger clock of the universe.

Now, I must admit that I was somewhat shocked, for lack of a better term, to re-discover a brief section in the epilogue of TEOT which deals specifically with the possibility of time travel! How could I have forgotten it? The answer to this question is, I regret to say, that his discussion of the topic is, sadly, in my opinion, quite forgettable. It is almost as though Barbour does not believe in the reality of his own theory of time! He states (p. 68), "What is the reality of the universe? It is that in any instant the objects in it have some relative arrangement." This is precisely my view! Barbour's "instants" or "Nows" clearly correspond with what I call "particular times." But whereas I see these relative arrangements of all the objects in the universe in a literal, real, naive, primitive sense, Barbour seems to see them as being abstract, mathematical concepts, just one of many possible hypothetical configurations in his relative configuration space of Platonia.

I sometimes have the impression that Barbour and I are looking at the universe and at the concept of time as though we were looking at a Necker Cube, an optical illusion in which it is possible to look at the same physical picture and arrive at two different interpretations of reality.

I hope this at least partly addresses the points you raised.

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Mr Smith

Thank you for your excellent & prompt response! I can see I must also revisit TEOT, having read it quite a few years ago. By the way, I was remiss in my previous post in not stating that I agree with you that time travel,in the Sci-Fi sense, ie possible causal violation, is not possible.

Have you read any of Barbour's papers or seen his mathematical formalism for deriving...

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Mr Smith

Thank you for your excellent & prompt response! I can see I must also revisit TEOT, having read it quite a few years ago. By the way, I was remiss in my previous post in not stating that I agree with you that time travel,in the Sci-Fi sense, ie possible causal violation, is not possible.

Have you read any of Barbour's papers or seen his mathematical formalism for deriving the "best matched" configurations? As I recall from the book, he uses a time-independent Schrodinger equation to achieve a static wave function which would "encompass" the possible configurations represented by points in his "Platonia". Then I assume he must remove the kinetic term from the Hamiltonian & work with just the potential. This would give rise to all the "changes" that define his "Machian distinguished simplifier". I recall having trouble reconciling this mechanism, which would give rise to zero energy states only, with the fact that, as he himself I think stated, locally or in any arbitrary sub-system of the Universe, there can be positive total energy, even though the Universe globally could have (must?) zero total energy!

Also, what does it mean to say that time is "the average of all the changes in the Universe" as defined by his "MDS"? I can understand him wanting to do away with local dynamics in favor of global configurations.....but an average?

This relates directly to my "twin paradox" point which you have responded to by quoting Barbour's statement of relativity dealing with physical clocks. This is certainly true to an extent. However, I raised this point directly in response to your suggestion that unique configurations represent specific times & I believe that you are still left with the problem of specifying which clock? Our observation of relativity is derived from our use of clocks, but I see that as secondary to the primary effect due to the absolute & reference frame invariant speed of light. I don't think you can simply say that relativity is about physical clocks.

I share your desire to find a model of reality which can be described purely in terms of relative configurations which still possess kinematics, true motion. I seem to recall Barbour using the example of a Kingfisher in flight to explain firstly, the difficulty of accepting that it isn't really moving and secondly, the way our minds give the illusion of motion by the use of "snapshots" of previous configurations which best match the current postion of the Kingfisher. This is something like Jim Hartle's IGUS hypothesis. But I can't help wondering, why does the Kingfisher have wings in the first place? Are Darwinian laws compatible with a static Universe? Can natural selection operate in the absence of classical kinematics?

Your Barbour quote "Time is change, nothing more, nothing less" prompted a thought experiment to pop into my head. What if the Universe underwent a "global boost", that is a uniform change of scale. As sub-systems we could have no way of knowing this was occurring. In Barbour's scenario, would this constitute a change in configuration? If yes, how would a notion of time arise & how could he derive an "MDS"? If no, how does the re-scaling occur in the absence of time or in his alternative framework?

I think, as you do, that we need a model which includes relative motion but can be formulated in a way Richard Feynman would like. Where the time components & time operators of our theories are replaced with relative displacements.

Thanks again for a thought provoking essay & good luck with the contest!!

Roy J.

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Mr. Johnstone,

Thank you for your thought-provoking comments, questions, and good wishes. I hardly know where to begin a reply, but perhaps a broad comment on my own background would be helpful to put things into perspective. First, I am not a professional physicist; I am a layman who likes to imagine himself as following in the footsteps of a long and honorable, but perhaps vanishing,...

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Mr. Johnstone,

Thank you for your thought-provoking comments, questions, and good wishes. I hardly know where to begin a reply, but perhaps a broad comment on my own background would be helpful to put things into perspective. First, I am not a professional physicist; I am a layman who likes to imagine himself as following in the footsteps of a long and honorable, but perhaps vanishing, line of what once were known as "citizen scientists." I mention this by way of responding to your question about whether I've read Barbour's papers or seen his mathematical formalism for deriving the "best matched" configurations. Let me say that I have looked at the papers which he has kindly made available on his website, but I will not pretend that I have been able to follow all the mathematics presented in the papers. This might explain why citizen scientists are a vanishing breed; science is becoming so specialized and complicated that few amateurs can truly master its intricacies.

My perspective on these topics is more qualitative than quantitative, a perspective which I hope may include a few advantages along with its obvious disadvantages. There is no risk of my being led astray by pursuing the siren song of elegant mathematics purely for its own sake, for example. I rely heavily, but not exclusively, on popularizations such as 'The End of Time,' 'The Trouble With Physics,' etc., to stay abreast of current thinking. Which reminds me that TEOT is now already a decade old. Perhaps we're about due for an update?

As to your question about why the Kingfisher has wings if there is no motion, that is indeed an excellent question. And why do we have legs, arms, and opposable thumbs? The argument for a static universe apparently is summarized thusly, "A classical theory that treats time in a Machian manner can allow the universe only one value of its energy. But then its quantum theory is singular - it can only have one energy eigenvalue. Since quantum dynamics of necessity has more than one energy eigenvalue, quantum dynamics of the universe is impossible. There can only be quantum statics. It's as simple as that!" (p. 253, TEOT) This is a case in which I fear we perhaps are being led astray by either the theory or the math or an unholy combination of both. On balance, I believe the evidence in favor of motion is stronger than the evidence against it.

Regarding your thought experiment involving a "global boost" in the form of a uniform change of scale, it appears that Barbour is toying with just such an idea even now. See his 'Dynamics of pure shape' under the heading Ideas at his website. Not having given it a great deal of thought, my first question would deal with gravity. Assuming the masses of objects do not change, and if we can consider them as point masses, then if we double all the distances between them wouldn't the attractive force of gravity be reduced by a factor of four? Wouldn't that be measurable? Or perhaps I'm missing your real point?

As to whether it would constitute a change of configuration in Barbour's scenario, you are raising some tough questions! These are questions probably best posed to Mr. Barbour himself. My first thought is that it would depend on whether or not any measurable effect resulted from the change. If we truly had no way of knowing a change of scale had occurred, then according to Leibnitz's principle of the identity of indiscernibles, if two things are identical in all their attributes, then they are actually one. If a change has no measurable effect, how can we call it a change? But again, I may be missing your point.

I hope some day we will have good answers to all these questions, but it probably will not happen tonight; the hour is late, and I fear that my brain is rapidly turning to mush.

Cheers!

.

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Mr Smith

Thanks again for your response. These brief discussions have prompted me to already begin reviewing TEOT following which I will look at the papers on Barbour's website. Then, as you suggest, I will pose any questions I still have (I think there will be many!) to him. If you like I will let you know what, if any, response I get.

Your comments regarding the "citizen scientist" & the way science has become so highly specialised & complicated are right on the mark. It has resulted in, for example, the mother of all "elegant maths for its own sake" "theories" - "String Theory" which I think, as a description of reality, at best barely qualifies as a model because no-one knows what it really is!

I too am a layman & it is refreshing to discuss these deep issues with another non-professional, non-mathematical, non-specialist, particularly one who shares the same basic view of the "problem of time"!! It would actually be good to keep the lines of communication going on this issue, in a different forum of course (email perhaps).

But for now, I have a lot of reading to do!!!

Cheers

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Mr. Johnstone,

I welcome the idea of keeping the lines of communication open. I don't know off hand whether FQXi offers a more private "back channel" for communicating email addresses or other personal information. If not, it might be a feature they should consider adding; other forums to which I've posted have offered this convenience.

In the meantime, this forum will serve well...

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At the risk of violating forum "etiquette" by submitting back-to-back posts (this ideally should be a dialogue or a multi-logue rather than a monologue) I would like to mention one other interesting (to me at any rate) ramification to the definition of a particular time which I have proposed in my essay (a particular time is identically equivalent to, and is completely defined by, and only by, a particular configuration of the universe).

This definition provides a clear and direct link between entropy and the so-called "arrow of time." According to the above definition, any observable change whatsoever in the configuration of the universe would constitute a change from one particular time to another. If the configuration of the universe were changing randomly, however, as it would in a state of maximum entropy, then time, too, would change randomly rather than "advancing" in the manner to which we have become accustomed to thinking of it.

A god-like observer of a universe having a configuration which was changing purely randomly (as it would at maximum entropy) would not perceive that the universe was "aging" in any meaningful sense of the term. Changing, yes; aging, no.

In order for time to change in a manner which an observer would interpret as "advancing" in some meaningful sense, the configuration of the universe must change in a manner which is (or which at least gives the appearance of being) non-random. For the universe to be truly and accurately characterized by non-random motion, however, it must be in a state of less than maximum entropy.

The universe in which we live is (fortunately for us!) at a state of less than maximum entropy, and its configuration is changing (evolving) in a more or less predictable manner according to some rule or rules which we strive to understand. It is this predictability of the universe's evolution which allows us to perceive what we have termed "the advance of time" or "the flow if time." Hence the correlation between increasing entropy and the arrow of time.

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There best argument I have for not being able to access a distant past_time, is if I could travel back to one nano second "ago", there would be hardly any change in the local configurations of nearby local matter, the T-REX or Tooth-Time concept?..but if I could lean out a bit farther back say to 10 nano seconds ago, still little alteration to local"structure" configurations, or say ten ordinary seconds ago, there would start to occur an entropy "creep" , which would inflict subtle little atomic changes.

Now go back to the diosuars tooth, a tiny alteration to the "then", lets say I scrapped a few atoms of enamel away, then a nano-second later I would not see any change locally (the tooth would still effectivly be total/complete)..but as the nano-seconds started to pass by, leading to one second then 1 hour..one day..1 millenium, then I would most definately alter many paths, or configurations?

Thus the farther one goes back in time, the more alterations would creep into our present time at an ever increasing rate,to the point of a present time being totally unstable?.. and things would start to disappear quite rapidly.

Its the butterfly effect, but on an evolution scale, a small shaving of a dinosaurs tooth "then" ,would have grave consequences for the large scale matter configuration "now"!

It must also operate as a two way process?.. the local alterations made whilst trying to pierce and probe backwards in time, would themselves have a "cause" effect locally, thus you could never really expect to fing those pesky "T-REX" monsters in an "ago", think about the configurations of matter, and the specific configuration of the space_time it occupies, the eponential changes that occur would really mean your historical past T-REX, would have to vanish agian in the "ago" era also? well thats what I believe to be so.

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The points raised regarding entropy are good ones & very relevant to the quaestions of the "appearance" of time & it's "arrow" & the reality of motion. You quite rightly say that random fluctuations in a Universe in total thermal equilibrium could give no sense of time "progressing" to a "God-like" observer in a way that we would recognise. In fact a maximum entropy state can & according to quantum theory must, randomly decrease or reverse it's entropy at some point in "time" & space, so that to a local observer, time might even appear to run backwards?

This relates to the distinction between different "arrows of time" ie the entropic arrow & the psychological arrow & the corresponding distinction between "time as change" & "duration". Relating this to the idea of time as unique configurations, if an observer experienced the configurations in the reverse order, they may perceive time to be running backwards while still having the same sense of duration "advancing" in time. This assumes the conscious observer's brain processes are not somehow reversed also!

The example of maximum entropy also impacts on whether Barbour's static configurations can be maintained by his "action" principle? The principle would seem to lose the power to "best match" the configurations. It becomes a question then of whether the mechanism he uses to constrain the wave function amplitudes to "coincide" with the "time capsules" can determine random changes, particularly in the case of entropy decreasing changes?

Paul, you seem to be using the argument of causal violation via a sort of two-way "multiplication" of effects as being the reason we can't travel in time . I think that would certainly be a consequence of travel to a past "point" in a consistent causal history. I simply believe we can't access "previous" points or "past" events for similar reasons to Mr Smith, that is, that the particular configuration which defines the event(time) no longer exists. I feel that any object has a "trajectory" relative to all other objects, defined only by it's relative position & relative velocity. These continuous relative trajectories are what create our notions of local time, in the case of similar non-relativistic trajectories, or relative "time" differentials in the case of large velocity and/or vector separations.

Does any of that make sense?!

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Mr. Valletta,

In a nutshell, as Mr. Johnstone has said, there simply is no longer any "ago" to which we can go back. All the messy "grandfather" paradoxes (or T-Rex with missing tooth enamel paradoxes) are obviated; history cannot be changed. The notion of the flow of time as evolving configurations of the universe "explains" the psychological arrow of time which is so eloquently captured in the well-known lines from The Rubaiyat of Omar Khayyam,

"The Moving Finger writes; and, having writ,

Moves on: nor all your Piety nor Wit

Shall lure it back to cancel half a Line

Nor all your Tears wash out a Word of it."

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Mr. Johnstone,

I'm astounded by how closely aligned our thinking is on this topic!

Even in a situation involving a statistical fluctuation in which entropy was randomly decreasing over some region, however, I don't think that an observer would perceive time to reverse. For example, if I were to look out on an interstate highway and see all the vehicles on the highway uniformly traveling backwards, I doubt that my first thought would be that time had somehow reversed; I'd more likely simply wonder why all the vehicles were backing up. If, on the other hand, I were to look up at the sky and see a 747 jetliner flying backward, I would be instantly and deeply confused (to say the least), because that sort of change in the configuration of the universe would violate the laws of aerodynamics (i.e., the laws of physics). Even in that bizarre case, however, I doubt that I would think time had reversed; more likely, I would question whether I was losing my sanity, or whether I were (hopefully) observing some bizarre optical illusion.

Our sensory systems and brains seemingly have been exquisitely programmed by evolutionary processes to observe our surroundings and to quickly and accurately calculate and predict the trajectories of the objects we see around us. This is how we have survived. Thus, while our brains may not fully understand all the abstract laws of physics, they understand well enough their practical consequences. I would strongly suspect that as long as our brains have the wherewithal to function, they will carry out this task to the best of their ability, regardless of how entropy may change. If we were to see the pieces of a broken cup leap up off the floor and reassemble themselves into a cup on top of a table we would question our senses, because that is not what we understand cups to do. Again, I suspect that we would be more likely to perceive it to be a violation of our understanding of the laws of physics than as a reversal of time. But these are mostly my off the cuff gut feelings rather than any carefully considered positions.

Regarding your comments about Barbour's action principle and best match procedures, I agree with you that it is not clear how these notions would fare in a universe at maximum entropy. Certainly food for further thought. Could this lead, for example, to some predictions or tests which would be falsifiable?

Thank you for your insightful observations!

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Mr Smith

Firstly, loved the Khayyam quote!

With regard to the reversal of entropy, I actually agree with you that a conscious observer would not perceive time to also reverse, although there have been one or two quite prominent theorists who have more or less considered this as a possibility in relation to cosmological "re-collapse" & a reversal of time's arrow. That was really my reason for including the notion of psychological time. A scrambled egg re-assembing itself would, as you said, certainly indicate a peculiar change in the laws of physics, but we would still observe it as happening in the normal advancing duration in which we sense all change to occur.

Our brain processes are still so little understood, that it is a fuzzy area in which to try to "validate" or build a model of reality upon. That's why I think that Barbour is on very shaky ground when he almost "assumes" that conscious minds can be static brain configurations & still have a "recognition" or "ordering" capability. This capability would seem to imply, to me anyway, that a process on another level is required. In Platonia it would require a "secondary" ordering process to "best match' the already "recorded" best matched configurations. But he could still be right as we know that our brains have evolved to perceive only a certain interpratation of reality that presumably maximises our survival. This all might have implications for free will as well?

Back to the topic proper, we do seem to be closely aligned in the essence of a model of reality as it relates in particular to the "nature of time". I am in fact working on a "shopping list" of what I would call "guiding principles" & relevant facts upon which to build a model. Off the cuff, three of them might be:-

a) Background independance (Obviously required for any "Machian" model),

b) Apparent time only emerges with mass or "measurement" by massive object.

c) Light (photons) really only 2 dimensional, ie Z axis is Lorentz contracted to zero & do not "experience" time.

I will compile a more complete list & hopefully post it here very soon, if you feel it worthwhile?

Cheers for now.

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Mr. Johnstone,

By all means, please do post your shopping list of guiding principles & relevant facts upon which to build a model! I'll look forward to it.

Back onto the topic of entropy and time, it must be obvious from my essay that I tend to take a very simple-minded, literal, naive view of the world. When thinking about entropy, I have a favorite "thought experiment environment" in which I imagine myself to be a microscopic being who resides on a molecule in a box of gas. The first order of business in this environment is to fasten one's seatbelt, because we're in for a bumpy ride, not unlike the bumper cars in an amusement park.

When the gas in my little "universe" is at thermal equilibrium, time (defined as configurations of my observable "universe") does change, but the changes are random (and hence "uninteresting"). On some very rare occasions, however, I might be fortunate enough to observe one of the rare, random statistical fluctuations predicted by Ludwig Boltzmann in which all the molecules simultaneously move to one side of the box. Wow! Now that would be exciting! I presumably would observe a temporary "compression" of my micro-universe, followed by a decompression and gradual return to equilibrium and random motion. During the compression and decompression phases, the observed motions of my neighboring molecules would, I believe, appear to be non-random, and hence "time" would briefly have a discernible direction (arrow), i.e., configurations would change in a seemingly non-random manner, but this short-lived "arrow of time" would gradually "peter out" and ultimately vanish after the gas had returned to equilibrium.

I fully agree with your comment regarding brain processes being too poorly understood to serve as *underpinnings* for a model of reality. (Ironically, however, it is these same brain processes upon which we must rely to judge the validity of a model once it has been constructed!)

The questions you raise about how all this stacks up against Mr. Barbour's Platonia are good ones, and I would like to hear how he would respond to them.

Cheers!

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Mr Smith

A thought or two on the point you mentioned in brackets regarding brain processes, which I think is an important one. It may be that we are incapable, even in principle, of fully understanding our brain processes because of the nature of those very same processes! Let alone being capable of fully understanding any "external" reality of which our brains give us a biased, "anthopocentric" view.

In relation to the "no motion" idea of Barbour's, presumably a perception of motion can only come with consciousness. If we put all this into the widely accepted "multiverse" model of inflationary cosmology & dare I say the "String Landscape" (it would be interesting to know if Barbour subscribes to either of these?) it becomes a question of whether motion is possible at all in principle. It seems to me that it must be possible as we already have physical laws that explain it, or are they just a product of our "illusory" brain processes? So, if we say motion is possible but just does not exist in our Universe, then in accordance with those theories, motion must occur in some number of Universes! The question then is back to why our Universe only "wants" to give us the impression of motion? (& whether conscious beings can exist in other Universes that do have motion?), & becomes a bit anthropic.

If we say there is only our Universe, then the existence of only "illusory" motion for conscious beings becomes even more anthropically motivated, lumped in with the other seemingly 'fine tuned" coincidences.

If we say motion is not possible, anywhere, then we would need to somehow falsify our current laws that are based upon it & prove that there are no physical laws that can allow it.

Could any of this provide a possible way to "test" or a means to "falsify" the 'no motion" hypothesis?

Must continue reading Barbour's literature & ponder this further but for now, my brain processes are scrambled!!

Cheers

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Mr. Johnstone,

The static picture which Barbour tries to convey has been, and remains, a huge stumbling block for me, and, in my view, it is unnecessary. The more I try to try to understand it, the more I fail to do so. Try as I may to make sense of it, the idea always ends up striking me as solipsistic. Since you are re-reading 'The End of Time' anyway, be sure to note Barbour's dialogue with Fay Dowker, which is introduced at the bottom of page 353.

As previously noted, my view continues to be that we can dispense with time as being something real *in and of itself* while not dispensing with motion. In fact, my view is that it is exactly motion which allows us to dispense with the old notion of time as some mysterious, stand-alone feature of reality while still allowing us to preserve our traditional psychological perception of "the flow of time." We simply need to shift mental gears to recognize that the flow of time is nothing more than the physical evolution of the universe, a process which necessarily involves motion and which should be described in a Machian, relativistic manner. This is not unlike the mental shifting of gears needed to move from thinking in terms of a geocentric universe to thinking in terms of a heliocentric universe. Nothing changes except the way we think about it, which, ironically, then changes everything!

Changing direction somewhat, I wanted to mention what I believe is another interesting aspect of thinking about particular times in terms of particular configurations of the universe. Although I have consciously tended, I hope more or less adroitly, to "finesse" the topic in my essays, we might reasonably ask how narrowly and/or precisely we may specify or define individual, particular times. It strikes me that the precision with which we can ever hope to define particular times is limited by two factors, one of which is our fundamental inability ever to have complete knowledge about the configuration of the universe, and the other of which is that even in a narrowly confined portion of the universe we will always be limited by the uncertainty principle from precisely defining a particular configuration/time. Hence, even at best, time at the quantum level will necessarily be "granular." At least food for thought.

Cheers!

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Dear Smith.

Nice to see that people has real sense for physics.

Discussions on time travel show that some physicists believe mind more than senses and so have lost contact with physical reality.

Time is information about change in timeless universe we obtain with clocks.

Universe is timeless and sure "time travel" is out of question.

Yours Amrit

attachments: 1_TIME_IS_INFORMATION_ABOUT_CHANGE_IN_TIMELESS_UNIVERSE.pdf

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Amrit,

Thank you for your comments and for sharing your essay, in which you wrote, "Ernst Mach said: “It is utterly beyond our power to measure the changes of things by time. Quite the contrary, time is an abstraction, at which we arrive by means of the changes of things”. Mach is right. Time and clocks are man-made inventions."

I hope it is clear from my essay that I fully concur with this view. There appears to be a growing recognition that this is the case. What remains to be done is to explore thoroughly the practical consequences of this way of thinking. What predictions will it lead to, for example? I spelled out one "prediction" it leads to in reference 4 to my current essay. Unfortunately, Einstein beat me to that prediction by about 100 years, give or take. But I'm sure there are additional, totally new predictions that we can make if we set our minds to it. These are exciting prospects.

Cheers!

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Mr. Johnstone,

A further comment regarding Julian Barbour's proposed model of a static universe. I try to remain open-minded toward Barbour's concept, difficult though it is for me to comprehend (this difficulty obviously could as readily reflect a shortcoming of my cognitive processes as any shortcoming of the concept itself). That having been said, however, I couldn't help being amused by a perhaps apropos comment which Einstein allegedly made regarding work done by Herman Weyl while they were trying to develop a unified field theory: "Apart from the [lack of] agreement with reality it is in any case a superb intellectual performance." (Quoted on page 45 of Lee Smolin's 'The Trouble With Physics.') Einstein's brilliance clearly extended well beyond physics to include the world of diplomacy. But that comment also captures my instinctive feeling toward notions of a static universe. Of course, instincts are not always to be trusted either. The proof is in the pudding, as the saying goes. What predictions could we make as a result of believing in a static universe that we can't make otherwise?

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Mr. Johnstone,

That previous post was from me . . . sorry I failed to add my name at the top!

jcns

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Mr Smith

I will continue my revision of Barbour's literature, then perhaps post a list of questions here for your critical assessment or supplementation, prior to directing them to him. Whilst I think it is time to concentrate on developing our own model of dynamically evolving configurations, his answers may provide valuable input. In the additional notes concluding his book, he does...

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Mr Smith

I will continue my revision of Barbour's literature, then perhaps post a list of questions here for your critical assessment or supplementation, prior to directing them to him. Whilst I think it is time to concentrate on developing our own model of dynamically evolving configurations, his answers may provide valuable input. In the additional notes concluding his book, he does mention three possible ways his theory could be disproved. 1) A mathematical proof that the wave function is not concentrated on time capsules (This is one I will ask him for an update on). 2) String Theory or some other successful quantum gravity theory reintroducing external time. 3) Direct evidence of wave function collapse.

Now, back in "motion land", we agree that all quantities of time should be re-interpreted in terms of spacial displacements. You have clearly stated this in your essay, including the resulting derivation of the mass/energy equivalence obtained in this way. These are precisely the sorts of predictions & proofs we need to start building a model. For instance, you mentioned in your August 14 post, the limiting factor of the uncertainty principle for precisely defining micro configurations. One aspect of this is the time/energy uncertainty, described in terms of the inability to measure wavelength in time. Conservation of energy is defined in terms of a time translation symmetry. What effect might it have on our understanding of nature if these were re-cast in terms of for instance, in the case of energy conservation, a symmetry of the spacial translation of configurations?

Back to your point regarding the limited precision to which we can ever define a particular configuration, I agree that the uncertainty principle limits this in the small scale regime. I also think, as I have previously stated, that on progressively larger scales, relativity must always proportionally distort any attempt to define a definite configuation, particularly where large relative velocities are involved. This is why I feel that your definition of time as stated in your essay, whilst being the correct conceptual basis, needs to be extended to include the effects of relative motion. I believe this would enable the precise definition of a configuration we are looking for, in the "4th" dimension of "velocity space".

This idea has similarities to George Ellis's "Evolving Block Universe" (see his essay in last year's contest), the main difference being that he retains a notion of advancing time along world lines. Whereas in the evolving "velocity space" the "boundaries" of the "block" are the maximal velocity differentials that can be achieved between an inertial frame "A" at or near light speed or, equivalently, at or near say, the critical gravitational horizon of a black hole & a frame "B" relatively at rest. Frame "A" could in principle observe frame "B" whizzing about indefinitely at the evolving "future boundary". This idea I think marries a fairly full application of relativity with your configuration space idea. This could also apply on the small scale if a quantum field was interpreted in the same way.

I realise this is all very sketchy, which is why I think it may be beneficial to list some guiding principles & relevant facts in point form, then perhaps collaboratively expand on each point to flesh out some semblence of a model.

Cheers for now!

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Mr. Johnstone,

On the topic of soliciting comments on our ideas from Julian Barbour, I have what I believe will be some encouraging words. When I submitted my essay to FQXi there was a provision in the submission form whereby I was offered the opportunity to name three persons whom I specifically would like to have as reviewers of my essay. (I hope I'm not "speaking out of school" here, as it were, but I do not recall seeing any stipulation that this information should be kept confidential.) So at any rate, the three reviewers I requested were Julian Barbour, Lee Smolin, and George Ellis (I'd noted Ellis's essay in last year's competition, too). Of course, I have no way of knowing whether this will actually happen, but if it does, I suspect the reviewers may well look at whatever posts are appended to the essay. So there is at least some hope that any comments which appear here will come to the reviewers' attention. As the saying goes, time will tell.

Btw, there recently has been a revised procedure whereby authors of essays are requested to log in before composing posts. The "system" supposedly will then automatically add the author's name at the top. This did not happen with one of my earlier posts (authorship was listed as "anonymous"). Perhaps there are still some bugs to be worked out. We shall see what happens this time. Even if it says anonymous, it's me.

I look forward to seeing your list of guiding principles and relevant facts.

Cheers!

jcns

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Mr. Johnstone,

By way of addendum to my previous post, I'd like to add that inasmuch as Barbour, Smolin, and Ellis are all members of the FQXi community, and inasmuch as they are all known to have an interest in the broad topic of this essay, it does not take a rocket surgeon to conjecture that they might read the essay. By specifically requesting them as reviewers I was simply trying to improve the odds.

I keep coming back to comments such as the one by Brian Greene which I quoted in footnote 1 in my essay. Smolin has made what I see as a parallel comment: "We have to find a way to unfreeze time -- to represent time without turning it into space. I have no idea how to do this. I can't conceive of a mathematics that doesn't represent a world as if it were frozen in eternity. It's terribly hard to represent time, and that's why there's a good chance that this representation is the missing piece." (page 257, 'The Trouble With Physics')

Perhaps I'm missing some blindingly huge and fundamental point, but it strikes me that viewing "the flow of time" as being nothing more or less than the evolution of the physical universe (a totally accurate view, in my opinion) should be a good starting point for a representation of time which unfreezes it. Yes, of course, as always, the devil will be in the details. Some sort of Machian, relativistic representation will be required, and I unfortunately do not know how to formulate that representation. I'm hoping that some smarter people will know how and that they will take on the job of doing so. I can't help thinking that it might lead to real progress toward sorting out some of the long standing puzzles in physics. That certainly is my hope.

jcns

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Mr Smith

There seems no doubt that the vast majority of physicists either openly or, when pressed, will say that we really have no understanding of what we call time, or any definite idea of how it should be treated in a fundamental theory. One consequence of this of course is the "problem of time", where we have two incompatible treatments in QM & GR, one of the barriers to a unified...

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Mr. Johnstone,

Just a very quick reply to let you know I've seen your post, and agree fully with the points in your list. I'm departing very shortly on unplanned travel, so may be less able to focus on this topic than usual for a while. Good question about possible insights from Goldfarb's way of looking at things. I currently don't understand it well enough to have a worthwhile opinion.

My quick gut feeling is that it would help at this point to hear from some of the recognized professional "heavyweights" in the field regarding their views on the points we've raised. I suspect that our ideas will only "gain traction," as the saying goes, if they are taken seriously and "championed" by recognized authorities in the field. I fear that I've about reached the limit of how far I can take them without input and support from the professionals in the field. More later.

jcns

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Mr. Johnstone,

This is being posted while I'm off traveling. I've been intending to mention one possible avenue we could explore which might prove helpful. In doing so, however, I'm obliged to admit that I've been seriously remiss in not having thoroughly pursued it already. In your post of 17 August you wrote, "Now, back in 'motion land', we agree that all quantities of time should be re-interpreted in terms of spacial displacements. You have clearly stated this in your essay, including the resulting derivation of the mass/energy equivalence obtained in this way. These are precisely the sorts of predictions & proofs we need to start building a model."

The mass/energy equivalence simply "popped out" on my very first experiment with substituting units of displacement for units of time, which I just happened to try with the definition of energy. This was, of course, most encouraging! What I am more than a little embarrassed to admit, however, is that I have not subsequently gone through systematically to apply the same procedure to the many other equations which appear in physics, i.e., doing the same substitution to see what other interesting things might pop out. Possibly other, similar "predictions" might pop out? Possibly even some that Einstein or others have not already made a hundred years ago? That would be exciting.

If you have any interest in pursuing this avenue, please by all means be my guest. And I trust it goes without saying that if you come across any interesting discoveries I'd be delighted to hear about them. Btw, this analytical technique was taught to me by my high school physics instructor, Mr. Carlyle Davidson, a wonderful teacher; he called it "dimensional analysis." Of course, he was not suggesting we replace units of time with units of displacement, but rather suggesting only that we carefully examine and compare units on both sides of our equations to be sure they match. If the units don't match, it's a clue that we'd done something wrong! If you do decide to give this a try, good luck and happy hunting!

Cheers,

jcns

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Mr. Johnstone,

With sincere apologies for perpetrating this running monologue, I've had some recent thoughts relevant to our topic which I'd like to throw out for your consideration. As background, I'm currently re-reading Smolin's 'Three Roads to Quantum Gravity.' I assume you've probably already read it, but if not, I highly recommend it. I find that in re-reading these books I'm bringing new ideas *to* them, and as a consequence I'm taking new ideas *away* from them. What follows is an example.

In discussing the topic of zero point motion Smolin writes, "According to quantum theory, no particle can sit exactly still for this would violate Heisenberg's uncertainty principle. A particle that remains at rest has a precise position, for it never moves. But for the same reason it has also a precise momentum, namely zero. This also violates the uncertainty principle . . . . " (p. 83, TRTQG)

Now, in a Machian universe (as opposed to a Newtonian universe) we must ask the question, "remain exactly still relative to what?" There is no fixed reference with which to measure "stillness." The stillness, or lack thereof, of a particle in a Machian universe can only be measured relative to all the other particles in the universe. In order for a particle to remain absolutely still in a Machian universe, it would need to remain absolutely still relative to every other particle in the universe. But this could only happen if every other particle in the universe was also absolutely still relative to every other particle in the universe. In other words, it could only happen in a totally frozen universe in which no particle moved relative to any other particle. If this were to be the case, then, clearly, according to our proposed definition of particular times as being equivalent to particular configurations of the universe, time would not change in this frozen universe. All processes would stop, including the cognition of any sentient beings who happened to be so unfortunate as to reside in this dismal universe.

This strikes me as being a more fundamental way to explain why it is not possible for a particle to remain absolutely still than trying to explain it in terms of the uncertainty principle. Which leads me to wonder whether this same rationale might somehow also offer a basis for understanding the uncertainty principle itself? Or is this a variety of the chicken and egg question? I've not come up with an answer to this one yet, but would certainly welcome any thoughts on any or all of the above.

I hope all is well with you. I have just returned from my unplanned travel, and am about to embark on some previously planned travel. Will do my best to stay tuned in while traveling.

Cheers,

jcns

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Hello Mr Smith

Please don't apologise for consecutive posts, as I must confess that my own will be rather haphazard due to unrelated work commitments that don't allow me much time to devote to these issues. So any time you have these thoughts, please go ahead & post them!

The point you have raised regarding a "Machian proof" of the necessity of motion is one that I must say I have never thought about in exactly that way, but will now ponder for it's implications, if things are as you say (the alternative would actually be very much like "Platonia"!). Regarding it's connection to the uncertainty principle, on first thought I would say they are not directly related. The Heisenberg principle is a direct result of the quantum nature of energy & so does appear to be fundamental to any description of nature, regardless of your preferred interpretation of quantum mechanics & without any other explanations required.

These issues, to me, do highlight some limitations of General Relativity in that, although Einstein was deeply influenced by Mach's ideas, they weren't fully realised in GR. In GR, the idea of a "stationary" particle can only be in terms of "co-moving" with another particle/s in an inertial frame (as opposed to the Newtonian view). This is the "special case" actually described by his famous (& somewhat abused) equation E=mcsquared, which really only applies to rest energy. So it is formulated on arbitrary co-ordinate frames which cannot be considered in relation to the "rest of the Universe", independant of a "space-time" manifold, as in your Machian picture. So it does in principle, allow a particle/body to be "static " when considered as a sub system. This sits somewhere "between" Newton & Mach I believe, ie no "absolute background" but also not completely "background independant". Then again, the depths of GR are still to be fully mined!

This provides food for thought in the formulation of our type of model, where all objects must retain a momentum/velocity component (motion) relative to all other objects. That is, any co-moving objects in a particular configuration, must still be defined with a motion relative to an evolving "global vector space" representing the evolving Universal configurations("times"). This vector/velocity space would represent our "4th dimensional measure" & could be considered to be orthogonal to the 3D's of ordinary space. Of course, velocity has dimension of time! So again, we need a way to re-define it in terms only of displacements...perhaps angles between vectors? As you said, we need help!!

Not sure how coherent that all is of the cuff?

Cheers

Roy J

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Roy and Mr. Smith,

You had some questions regarding the insights the ETS may provide into some of the questions you raised. I cannot really help you, except to mention the following.

Physics, as we know it today, starts and ends with the measurement, and we should not forget that! What I am proposing is to change radically the very concept of measurement: from numeric to structural. And so *all* of physics should change. Of course, eventually we should be able to connect with the existing physics, but at the beginning it is not prudent to do so, since we would be guided by the wrong considerations.

Most of the implications are such that we cannot know them now. The only reasonable thing we can do now, if we adopt the formalism, is to follow the logic of the new forms of ‘measurement’. In particular, the concepts of time, mass, space, etc., as we know them, become obviated. What should replace them? Again, we cannot know it now. We need to proceed with the utmost caution, and thus our main difficulty is that we have to start from the *very* beginning, and this is at the time when everyone wants to proceed along well developed roads.

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Mr. Goldfarb,

Thank you for your comments regarding the questions we'd raised about the possible applications of ETS to the issues we're addressing. Speaking only for myself, I have to say that ETS is not a concept which is easily grasped on a quick first, or even second, reading by one who has not previously thought about it or had some background in the topic.

I certainly agree with your observation about the importance and even centrality of measurement in physics. Good luck out there on the frontier with this new way of looking at the world. I will look forward to seeing future developments and results from your efforts.

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Mr. Johnstone,

The comments in your last post certainly seemed coherent to me, and on the mark, as usual.

Apropos of probably nothing helpful, I occasionally find myself wondering about the center of mass of the universe. I have not investigated whether this topic has already been thoroughly addressed somewhere in the literature, but I seldom see it discussed in writings on physics or cosmology, perhaps because it has been investigated and determined not to be helpful?

Assuming the universe is a closed system, it must have a center of mass. If so, would it be possible for observers within this closed system to perform any experiments which would allow them to determine the actual physical location of the center of mass? And if so, might that be a useful point of reference for a relational system of dynamics, i.e., by somehow relating motions to the center of mass of the universe? But enough of this idle speculation. As you can see, I'm reduced to the point of grasping at straws. Yes, help from some of the "heavy hitters" on these topic would be most welcome.

Cheers,

jcns

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Mr Smith,

I think you will find that almost all the literature would say that there is no sense in which the Universe can have a centre of mass. In any of the "Big Bang" models, space & time are created from essentially nothing, so that a Universe (or domain) becomes the ultimate "affine space", ie having no point of origin. So that, if the Universe is "closed", it is only in the sense of being spatially finite on an *unbounded* surface (eg surface of a sphere). It then becomes a matter of being only able to compare local *relative* centres of mass between relative configurations. That's my take on it anyway!

I have thought again about your Machian proof of the necessity of motion, where motion of a particle can only be fully defined relative to every other particle in the Universe and possible connections to the uncertainty principle. Considering this together with Lev's comments regarding the current paradigm of measurement, I can see a sort of connection to the Bohmian Mechanics model which appears to potentially take the mystery out of quantum mechanics, including the "measurement problem". It does this in part by having the particle positions and momentum states being fully dependant on *all other particle positions and motion* populating the wave function.

This Bohmian model of quantum physics could almost be a micro scale basis for large scale configuration model??

Cheers

Roy J

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Mr. Johnstone,

Thank you for bringing me up to date regarding current thinking about the center of mass of the universe. You are a veritable font of knowledge! Your knowledge of physics and cosmology appears to belie your claim of being a mere layman. Regardless, I had pretty much concluded that this idea about the center of mass of the universe must not be a fruitful one; otherwise there probably would be more evidence of it having been heavily trodden by now. Not always a reliable indicator, of course, but often so, while always bearing in mind that sometimes the paths less trodden can be of value, too.

It has been many years since I've read any of David Bohm's writings. Is there a particular title or paper you'd recommend which would serve to re-acquaint me with his thinking relevant to the topics we're discussing? As has become clear from of my re-readings of Barbour and Smolin, there probably was much of value in Bohm's writings which did not fully register or "sink in" with me during those earlier, first readings. The adage that what one takes away from a book is partly dependent on what one brings to it has been heavily reinforced for me of late.

Thanks again for your very helpful thoughts and comments.

Cheers,

jcns

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Hi all ,

What a beautiful discussions ,thanks to both of you for these relevances .

I read them with a lot of interest .

Sincerely

Steve

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Mr. Dufourny,

Thank you for your kind comment. Please feel welcome to join the discussion. Helpful ideas are always welcome.

jcns

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Mr Smith

On Bohmian Mechanics, I would recommend that you visit the website "www.bohmian-mechanics.net/". This is the homepage of a group of collaborators, Durr, Goldstein, Zhangi et al, who are working on what I think is the most promising extension of Bohm's ideas & "hidden variable" theories in general. They have actually received a grant from FQxi to develop their model. Their site contains many references to books & papers covering the historical development, including the first Bohmian ideas from Louis De Broglie (of "matter waves" fame) pre dating Bohms first published paper by 25 years! as well as the latest developments.

As I previously mentioned, their model can potentially be applied to the Universe as a whole in the context of a deterministic, wave functional configuration evolution. One drawback, at least to date, appears to be that a Bohmian model is inherently non-relativistic, eg configurations are described using a common absolute time. Inherited of course from quantum mechanics.

Regarding this and cosmological issues around open/closed & finite/infinite Universes, you might like to have a quick look at discussions on the comments page to Julian Barbour's article "Is The Universe Expanding?". Recent posts have been quite relevant to these issues, with some interesting technical input from Lawrence Crowell, including his pointing out to me that in the Bohmian model of the Hydrogen atom, the electron is considered to be *stationary* due to a constant phase factor! This is quite puzzling & still has me scratching my head & looking for an interpretational loophole!!

Cheers

Roy J

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Mr. Johnstone,

Thank you for the excellent suggestions. I'd read Barbour's article ("The Non-Expanding Universe"), but had not gotten into the related posts. Having now given them just a very cursory glance to gauge their magnitude, I agree that they certainly are relevant to our discussions. So much to read and digest, so little time.

The best news of all from the Barbour article, of course, is that he's working on a new book. With "The End of Time" being now 10 year old, much sand has trickled through the hour glass since it was written. I'm of course hoping that the new book will address some of the issues we've raised here.

Now off to immerse myself in some of these various readings which you've so kindly recommended!

Cheers,

jcns

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Hi dear Mr J.C.N.Smith and all ,

I was very fascinated by this papper ,you know I am going to tell you an idea about the evolution and the rule of dynozaurus ,the evolution shows us a specific sequences of building and optimization by the fundamenatl complementarity.

All is linked without any doubt since the beginning and for the future towards this harmony between mass systems .

For exemple The dynnosaurus were bigs ,and a big animal can accelerate the decomposition and thus the catayzation of the ecosystems .What I say is very simple all had ,have and will have a specific rule on the evolution time line constant .The past is evidently the past and a causes of our actual system .

A big animal is easier to decompose or catalyze the alimenatry chain and the nature too around them .

All evolves it's evident towards a complexification and a harmonization everywhere in our physical universal sphere in optimization.

All the universal memmory is in all ,this link is fascinating .The future optimizes itself towards a beautiful incredible sphere of interaction between mass systems and their lifes and buildings .I think what the increase of mass by weak interactions is fascinating ,we polarize all time ,all complexificates itself in a optimization of complemenatrity in all systems ,quantum and cosmological .

Congratulations for this essay dear Mr J.C.N. Smith ,?I read it with a lot of interest ,it's pragmatic and rational .I beleive what The past if to analyze ,the present to evolve and learn and optimize systems and the future to continue this complexisfication by probably many exponentiels ,Fascinating our Story ,and the word is weak .I dream so much about the future ,sure we were in the past ,we are in the present and thus we shall be in the future becaus all is linked evidently

Kinds Regards

Steve

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I try to imagine the center of our Universal sphere .Logically we turn around but how ,that's the question ,where are we in fact and how to relativate our perception correctly .

Our Univers has a specifi sequence of building ,a specific building where all evolves ,takes place like a code of becoming in fact .But how correlate correctly all that with a balance between the perception and the...

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Hello J. C. N. Smith,

Loved your essay!

I also agree that time travel into the past is not possible, as time as measured on wour watches is not the fourth dimension, but rather a phenomena that arises because the fourth dimension is exapinding realtive to the three spatial dimensions, or dx/dt=ic, from which all of rwlativity and quantum nonloality and entanglement...

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Dr. E,

Thank you for your complimentary comment on my essay. I'm currently traveling, and have not had an opportunity to ponder your fqxi essay from last year, your MDT ideas, etc. In quickly skimming some of the related threads, however, I was disappointed to see what appears to be some rather serious and unsubstantiated allegations and innuendos regarding a lack of objectivity and a prevalence of "insider-ism" vs. "outsider-ism" and favoritism in the awarding of prizes in last year's competition. Frankly, much of this talk this had a strong scent of sour grapes about it. Given a sample size of exactly one (annual competition), the allegations appear considerably stronger than the available evidence would support. I see the fqxi forum as being a welcome one, and I would poison this well only extremely reluctantly and only with very strong supporting evidence, none of which I saw in my admittedly somewhat cursory scan of the various threads.

Best,

jcns

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Thanks J. C. N. Smith!

Yes--fqxi is doing a noble thing here, and it is not easy.

They are of course to be overall commended!

But too, I've got to call them as I see them, even if it sometimes sounds harsh. I was far from alone in my words of constructive criticism.

I hope nobody takes it personally, as again, FQXI is providing a most unique and invaluable forum. They are expending both a lot of time and financial resources in furthering their noble pursuit, so thanks to all!

And I think this year will be even better.

Best,

Dr. E :)

Dr. E (The Real McCoy)

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Dear J. C. N. Smith,

I think the time paradox is the Recurrence relation problem for Time scale in Inflationary Universe. Thereby we may have to re-model the Universe in that the prior configuration cannot be restored in reversal of time.

With Best wishes,

Jayakar

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Mr. Joseph,

I think that perhaps I am not understanding the point you are making in your comment. If the flow of time is seen to be nothing more and nothing less than the evolution of the configuration of the physical universe, then "time reversal," per se, is not a realistic expectation or option. The only way "time reversal" could happen would be if *every* particle in the universe were to simultaneously experience an exact reversal of momentum. The statistical likelihood of such an occurrence is infinitesimally small. Lacking such an improbably event, time reversal will not occur. Which is not the same as saying that the universe could not eventually evolve toward a "big crunch" followed by another big bang, etc. But moving from our current configuration to a hypothesized big crunch would not require a time reversal. Time could simply continue to "flow," i.e., the physical universe could simply continue to evolve, toward the postulated big crunch, assuming that this is what the laws of physics require as a natural outcome. To the best of my knowledge, however, the jury is still out on that issue.

Best,

jcns

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Mr Joseph/Mr Smith,

Whilst I haven't heard of Mr Joseph's "Recurrence relation problem", it sounds to me like it could only be in the context of a "cyclic Universe", where a reversal of entropy at the beginning of the contraction phase has been proposed as the basis for time reversal. As Mr Smith has stated, apart from that view being rather dubious in it's own right due to *local* systems still increasing in entropy creating "regions" with different "time arrows" etc, a model with evolving configurations as "time" would preclude the paradox of "restoring" or "reverting to" a prior configuration. It is interesting to note that, at least in the literature I have seen, when the cyclic model is represented two dimensionally with say, X axis as time and Y axis as space, the evolution is always a parabolic curve from the origin to some larger value of the X coordinate when Y again takes the value zero! Time continues in the same direction!!

In the evolving configurations model, it may still be possible, if highly improbable, for a "previous" configuration to randomly "appear" again, given certain assumptions about entropy. Given also that this model cannot be "temporally" infinite and may be constrained to be spatially finite (for Machian reasons), the model may need to be represented as an *infinite* configuration/vector space. This is where we get into the murky waters of "model versus reality". But I may be wrong about this possibility. It may be that this possibility *is* realised in the vector sub-space representing thermal equilibrium, where random fluctuations around the maximum entropy phase could even oscillate between "identical" states? Of course in our model, this has nothing to do with "time" reversing, but with the vastly increased statistical probability of highly uniform microstates transforming.

The cyclic model would seem to be reliant on current observations showing the Universe to be "open", ie "flat" (omega = 1) or having slight negative curvature, being wrong. Any other ways time can reverse or "loop" back on itself, would seem to involve certain solutions in GR. Again, a convincing quantum gravity theory may resolve those issues!

Cheers

Roy J

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Mr. Johnstone,

Due to travels, readings, and various other "distractions," (if it is fair to call "real life" a distraction from our "on-line life," the very thought of which shift of perspective is more than a tiny bit frightening) I've been only intermittently tuning in to the various ongoing conversations here at the fqxi website. To do them all justice would be more than a full-time job for anyone. Have done a bit of "lurking" on the thread from the Barbour Non-Expanding Universe article. Concur with your comments there, but did not feel able to add anything of worth to them.

In one of the many fqxi essays or threads I've skimmed recently I saw a disturbing quote, allegedly from an Einstein correspondence written late in his life, in which he supposedly despaired of the possibility of ever formulating a truly Machian description of the universe. As I recall, the quotation was not sourced. Unfortunately, I failed to note exactly in which essay or thread I saw it. Would you happen to know about it, especially regarding its authenticity? If not, I'll go searching for it again. I would like to go back to the original source to learn more about the context of the alleged comment, which, if true, could not be taken lightly; certainly few, if any, have thought more deeply about these issues.

Cheers,

jcns

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Hello Mr Smith and Mr Johnstone ,all,

It's interesting all that .

I don't think what the Big Crunch will be ,on the other side ,a harmony between mass is more logic ,it's the same with the Big Bang ,it's rather a kind of placing ,arrangement with a multiplication of quantum spheres like a spherical fractal ,a kind of mitose of quantum spheres .Thus it's just a fact to encircle the gauge .

I consider the rotations of quantum spheres like the link with mass ,thus I can imagine the space like quantum spheres without rotations,thus mass.But they are coded and probably activate themselve by thermodynamics ,considerant the decrease of space and the increase of mass .The density,the mass increases due to a kind of activation for these spheres without rot thus mass thus rule and becoming with its specifics quantum architectures and its spheres ,very numerous like our cosmological spheres ,the volumes of mass and the volume of space are linked in the specific dynamic of our Universe .For the space ,the lattices between the entanglement of quantum spheres ,the sphere is the best form to rotate and furthermore the contact is optimized ,the gravitational waves in this logic are relevant too and the superimposings in the two senses ,quant and cosmol.can permit to link all with these fundamenatl I think rotating quantum and cosmological spheres with the evolution in Time and Space of course to insert the increase of mass and the complexification by polarizations,our quantum codes evolve and complexificate with the very weak interactions .The time in this logic is essential like a constant for the strong interactions ,the evolution of diversification and complexification of spheres continue .Sometimes I say me probably the pole of light is one and the quantum stability in time is the second in the ultim gauge ,thus a linear and a non linear ,thus two senses between the entropy ,and our limits ,walls ,planck dimensions .

Of copurse it's a hypothesis .

What do you think ?

Steve

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This Entropy behind ,and if that was the light which becomes mass in an evolution in the physicality ,the light creates the mass ,the lifes ....so spiritual and logic in fact .

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Mr. Johnstone,

I'm not sure whether you continue to check back in on this thread from time to time, but in case you do, I wanted to add a follow-up to my previous post regarding my recollection of having seen an alleged quote by Einstein (circa 1954) in which he despaired of formulating a truly Machian description of the universe. I have now searched the likely threads and essays here at fqxi without success, and am beginning to wonder whether I might have simply been mistaken or imagined the whole thing. Certainly, if such a dramatic and noteworthy quote is in the public domain, I would expect to see some references to it in Barbour's 'The End of Time' or elsewhere.

Unfortunately, the Princeton University Press series on Einstein's collected papers currently only extends to as recently as 1921 ( http://press.princeton.edu/catalogs/series/cpe.html ). Unless they speed up their publishing schedule a bit, his collected papers for 1954 may not appear during my natural lifetime.

Bottom line: should you happen to stumble across such a quote in any of your obviously voluminous readings, please make note of where you find it and let me know. Many thanks. And of course should I find it I'll post a reference to it here as well.

Cheers,

jcns

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Mr Smith,

I do check on all FQXi discussion threads as often as I can, particularly of course this thread! I did my own quick search through the essay threads and also drew a blank. Lurking in the back of my mind is a vague recollection of seeing an Einstein quote to that effect. I will continue searching when I can, as it is important of course to see what context he was talking in, if indeed he said it!

At the moment I am concentrating on possible extensions to Bohmian Mechanics which attempt to make it relativistic & Lorentz invariant so that it can apply at all scales & therefore to our concept. Still getting my head around that static hydrogen electron too! Surely it can't be right!!!

Cheers

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Mr. Johnstone,

It's comforting to read that you also have at least a vague recollection of having seen the Einstein quote. I'm hoping my subconscious didn't simply fabricate it from whole cloth. Have been reading so many essays and threads recently that things have begun to blur as to exactly where I've seen what. I'm definitely kicking myself for not having paused long enough to make a careful note of where I saw that particular quote, however, assuming I did in fact see it. Lesson learned; haste makes waste. Perhaps other fqxi denizens who stumble across this thread will have better memories and thus be able to help us sort it out.

Good luck with your other related pursuits!

Cheers,

jcns

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Mr. Johnstone,

Just a very quick comment on the static electron: I haven't been following your deliberations on this so am hesitant to comment without knowing the background, but is it possible that you're looking at some sort of standing wave phenomenon which might be indistinguishable from a "static" electron? Just a thought, but I suspect that either this is not germane to your context or else you've probably already considered and dismissed it.

Cheers,

jcns

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For readers of this thread who have more than a passing interest in "the problem of time," I'd like to offer links to a couple of papers which are highly relevant and thought provoking.

1. 'A Possible Solution to the Problem of Time in Quantum Cosmology' by Stuart Kauffman and Lee Smolin, 5 March 1997, http://arxiv.org/pdf/gr-qc/9703026v1

2. 'The present moment in quantum cosmology: Challenges to the arguments for the elimination of time' by Lee Smolin, 30 August 2000, http://arxiv.org/pdf/gr-qc/0104097v1

Enjoy!

jcns

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Mr. Johnstone,

In the first of the two papers I referenced in my previous post one may find the following:

"One has simply a set of rules by which a set of possible configurations and histories of the universe is constructed by a finite procedure, given any initial state. In a sense it may be said that the system is constructing the space of its possible states and histories as it evolves.

"Of course, were we to do this for all initial states, we would have constructed the entire state space of the theory. But there are an infinite number of possible initial states and, as we have been arguing, they may not be classifiable. In this case it is the evolution itself that constructs the subspace of the space of states that is needed to describe the possible futures of any given state. And by doing so the construction gives us an intrinsic notion of time." (page 11)

Is it simply my fevered imagination working overtime or is it possible that the above is simply a more rigorous way of stating that a particular time is identically equivalent to, and is completely defined by, and only by, a particular configuration of the universe, and that "the flow of time" is nothing more and nothing less than the evolution of the physical universe?

Inasmuch as we tend to see these issues from a similar perspective, I'd welcome your thoughts here. In other words, sanity check appreciated. Thanks.

jcns

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Mr. Smith,

I enjoyed reading your essay. I am a believer in a real, objective Universe, otherwise said "what we see is what we get", no extra dimensions, no dark energies or or dark matter... only phenomena waiting for a simple explanation. That leads me to believe that reversing the time falls in the same category with the assuming that objects may exist with negative dimensions ... Like you mention in the paper, it is difficult enough to find out what in fact are we trying to reverse? How you "reverse" time for atoms which are part of a bigger picture? It is obviously that even if it is very weak, we are gravitationally bound to the center of the galaxy. Are we going to "reverse" that too? Is there a cutting point for those interactions? I think that the entire speculation comes from confusing "slowing down" with "going back."

I am also a big fan of John Wheeler. I wholeheartedly agree with his comment about time you quoted in the essay:"We don't realize we're the source of the puzzle because we invented the word." I am not an expert in physics or mathematics, but I have been using both in my practice. As an engineer I am always translating this quote into a more practical "just because you can, doesn't mean you should..."

Best regards and best of luck with your essay.

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Mr. Coman,

Thank you for your kind and encouraging words. I like your "translation" of Wheeler's quote. Sounds like good advice. Wheeler certainly is one of the most frequently quoted of all modern physicists, along with Einstein of course. He represents a now mostly vanished generation of physicists who we revere for their humanity as well as for their thirst for a deeper understanding of the universe. One of my greatest treasures is a personal letter which I received from Mr. Wheeler in reply to a monograph I'd mailed him. I'd mailed copies of the same monograph to probably dozens of younger physicists, but Mr. Wheeler was one of the very few who took the time to reply, and a most gracious reply it was.

Good luck with your essay and with your ongoing professional efforts, too!

jcns

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Mr Smith,

I think your sanity is probably safe! Without knowing the context ie the "finite procedure" these statements relate to, they would seem to be consistent with an evolving configuration based description of reality, with future "time" being dynamically determined, rather than the "block Universe" description of GR with time being "moved through" by massive bodies. I think I may have read both of those papers at some stage, but now might be a good time to review them when I can. I know Lee Smolin seems to have changed his mind about the reality or at least the "utility" of time in recent years and that seems to be borne out in the title to the second paper.

Regarding the mysterious Bohmian static electron, it seems to have more to do with the wave function for the hydrogen ground state being real valued (ie not complex). I must say at this stage that the explanation & justification for this seems just as mysterious to me as the mysterious quantum behaviour Bohmian Mechanics is supposed to explain!! But it just may be beyond me to understand the technicalities, at least at the moment. It is probably trivial in the wider application of the theory anyway.

Cheers

Roy J

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Dear J.C.N. Smith,

The mainstream physics affirms that time travel is impossible. All physics textbooks prove the impossibility of time travel. And you prove the same impossibility of time travel. Do you think such essay advances the physics? The present essay context looks for ideas at the limits of physics. Do you have any ideas at the limits of physics? The most part of scientists are sure that time travel is impossible and they do not need in additional proofs.

Imagine that I’ll write the essays: On the impossibility of violation of energy conservation laws; On the impossibility of violation of Albert Einstein's general theory of relativity; Maybe I mist write the essay: 'The Newton gravitation theory is true'. All these papers do not advance physics, they repeats the known statements only. In the same way, your essay repeats the known already statement that time travel is impossible.

Your arguments from essay are non-convincing:

1)You wrote 'a carbon atom which once resided on the tip of Cleopatra's eyelash may now reside on the tip of your eyelash'

Time travelers use the Everett's multiverse theory to travel in past. In this case your arguments fail. A carbon atom which resided on the tip of Cleopatra's eyelash is from the Universe number one whereas another carbon atom is from universe number two. There is no paradox here.

2) Your arguments about the particular time and configuration of universe also do not work for case of multiverse theory;

3) You wrote ‘we believe that it is made up, of the same bits and pieces which formerly were arranged very differently to include dinosaurs’ If the observer jumps from one universe to another, all your arguments fail.

Since each new configuration of Universe replaces the previous configuration, consequently it is a physical process. In order to travel in time we must control this process.

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Mr. Leshan,

Thank you for your comments.

You wrote, "All physics textbooks prove the impossibility of time travel." If this is true, can you please explain for me why numerous respected physicists continue to speculate about the possibility of time travel? References 1 and 2 to my essay were intended merely as representative examples of this genre, not as an exhaustive list.

Your arguments invoking Everett's multiverse theory clearly hinge on that theory or other, similar multiverse theories being generally accepted as correct, which I believe is not the case. Until stronger evidence is presented for the existence of multiverses, I'll continue to focus my attention on the one (and only) universe which I'm able to observe.

You wrote, "Since each new configuration of Universe replaces the previous configuration, consequently it is a physical process. In order to travel in time we must control this process." Yes, I totally agree with you on this point. As soon as we devise a way to manipulate and control the configuration of the entire universe (e.g., if we could arbitrarily return the entire universe to a former configuration, for example), then time travel might indeed be possible. Good luck with this project! I hope that when you've figured out how to accomplish this feat you'll explain it in an essay here at FQXi.

jcns

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Mr. Johnstone,

Reassuring sanity check much appreciated. Regarding the mysteries or Bohmian Mechanics, I freely (if regretfully) acknowledge that the technicalities of this topic currently exceed my grasp. Good luck with your investigations, especially as they apply to the problem of time. Any resulting conclusions which can be explained in lay terms will be most welcome. Thank you.

Cheers,

jcns

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Re: "All physics textbooks prove the impossibility of time travel".

I think it would be much more accurate to say that most physics textbooks describe paradoxes that *should* preclude time travel and that the majority of physicists agree that it should not be possible, however I don't recall seeing any proofs. The whole question of how to treat time in current theories is still open. In fact, the "mainstream" theory for the macroscopic world is General Relativity, a theory which allows solutions giving closed time-like curves, wormholes, singularities etc, all of which are undesirable and can in principle allow time travel/causality violation. Einstein himself didn't realise the full implications of his theory!

Everett's Relative State theory ("many worlds") was a response to the Copenhagen "observer created reality" weirdness, but when used as an "escape" from causal violations (eg Grandfather Paradox), itself relies on time travel via GR to be possible. The challenge is to falsify these solutions or find a way via quantum gravity/cosmology or even string theory to avoid them. This is an ongoing process.

So, whilst "mainstream physics" may "affirm" that time travel is impossible, the "proofs" are not yet there. Clearly stated principles relating to the nature of time such as that put forward by Mr Smith in his essay, whilst perhaps already intuitive, are I think a necessary step on the way to a full understanding of reality. We know that GR is incomplete, as is quantum mechanics and until they are either unified or replaced by something better, we will not have the evidence we need to prove the impossibility of time travel.

Cheers

RoyJ

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Well said! Thank you!

Cheers,

jcns

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Mr. Smith, I enjoyed reading your essay--and I certainly agree that we won't be hobnobbing in past or future times (except psychologically)! My question is, What is the duration of Present Time?

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Mr. Craft,

I'm glad you enjoyed the essay. Your question about the "duration" of the present time is a fair one; I wish that I could give you a good, simple, straightforward answer, but I can't. I suspect that our notion of "duration" is a relic, a holdover from our old, conventional ways of thinking about time, but even this is not one hundred percent clear to me.

The universe is what it is. We observe that it evolves; the challenge is to describe that evolution without invoking the old, separate, conventional quantity of time in the process of doing so. As always, the devil is in the details. Fortunately, people who are much smarter than I am are giving these issues a great deal of thought even now. Aside from cheering them on, I'm afraid I've not been of much help in this regard.

Please do check out reference 4 to my current essay if you ever have time; it looks at some of these same issues, but from a somewhat different perspective which may shed additional light on the topic.

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Mr Smith ,

You say

Wheeler certainly is one of the most frequently quoted of all modern physicists, along with Einstein of course.

I prefer Mr Bohr ...it's the main piece ,and his son of course .

But I recognize his extrapolation and some interesting mathematical imaginations .

Mr Tegmarg probably is a fan of Mr Wheeler .

I think what the sciences aren't...

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The past is to learn ,the present to act and the future to evolve ....

Time is a constant of evolution towards harmony .All chaotics systems shall disappear with or without our approbation ,our proposal ,our whishes .

The Faith is universal ,and any human systems can contredict that .

Sincerely

Steve

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Dear J.C.N. Smith,

I published a Time Travel method here:

Can you find any errors in this Time Travel method? Pay attention that my method allows time travel to future only. I wrote in my paper that time travel in PAST is possible if multiverse theory is true only.

If multiverse theory is wrong then my theory allow time travel to future only.

The modern physics allows time travel into future. It does not violate causality and conservation laws. Thus Time travel is possible!

Sincerely, Leshan

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Hi Leshan ,

You are incredible .hihihi a real catalyzer of threads .You are likeable in fact .

Sorry but it's impossible to travel in Time ,the dilatation of Time by Einstein is so complex ,but never he said what it was possible .

He said what the space and time are linked and the space due to the gravity changes and produces gravitational waves .

It's totally different...

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Dear Steave,

Outside of Universe does not exist time as a property. Therefore if we send a body outside of universe, we 'froze' a body, for example for 100 years. Outside of Universe a body experiences no time because time dilation is infinite. After 100 years a body reappears again in the real universe. It is time travel to future. No physical laws are violated.

You wrote: In your essay, why did you say what the waves are infinites.

I examine there how to travel in time using quantum mechanics. All bodies are particle-like objects with wavelength l=0. For time travel we must transform a body into a wave with l= infinity due to a body disappears. Then its wave-function collapse and this body reappears in another place or time

Yours Leshan

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Mr. Craft,

I'm taking the liberty of posting this to the thread for your essay as well as to the thread for mine, because I'm not sure whether or how often you check back on the thread of my essay where you posed the excellent question, "What is the duration of Present Time?" I'd like to add to the reply which I offered earlier, which I fear was not very helpful. If you have a deep and burning desire to understand the concept of time, the best advice I can give you is to read the book 'The End of Time,' which was written by Julian Barbour and published in 1999. It is now available in paperback. While I don't necessarily agree with all of Mr. Barbour's thinking, I find his book to be an excellent source, a veritable treasure trove, of information about time.

Relevant to your question about the duration of the present time, for example, Barbour writes, ". . . Einstein's approach to relativity led him to an explicit theory of simultaneity but an implicit theory of duration. It is the latter that is important for this book, but it never got properly treated in relativity. . . . Poincare's 1898 paper showed that [the theory of time] must answer two main questions: how simultaneity is to be defined, and what duration is. Associated with the second question is another, almost as important: what is a clock? Because of his approach, Einstein answered only the first question at the fundamental level." (pp.133-135 of 'The End of Time,' hardback edition.)

The best news is that Barbour apparently is about to publish an eagerly anticipated update to 'The End of Time.' (See the essay about him at the main FQXi Community page.)

Good luck with your reading!

jcns

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Lets put it another way?..can you travel anywhere without Time? can anything in the Universe, move from one location to another, without the concept of Tine ;)

Think hard about it!

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Mr. Valletta,

Thank you for your comments. In fact, I *have* thought quite hard about it! You'll find some of the results of all that hard thinking, such as they are, here: http://smithjcn.googlepages.com/time

Enjoy! Comments thereupon of course welcome.

jcns

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Mr. Leshan,

I have read your essay from last year's essay competition, as you suggested. It seems that your ideas about time and about the notion of time travel are so dramatically different from mine that I'm at a loss even to know where to begin commenting on your proposed method of time travel.

To my own way of thinking (as explained in my current essay) time travel, were it possible, would entail somehow traveling from one particular time to another particular time. Inasmuch as we seem not to share a common notion or understanding of what constitutes a particular time, however, I fear that there is not much left beyond that major disconnect to discuss. Perhaps it would help me understand your thinking if you would explain your concept of what constitutes a particular time. Thanks.

jcns

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Well ,

Dear Mr Smith,

In your papper on google ,here is some words ...."

nature is telling us that time and space are equivalent; time becomes space; they should be measured in the same units.” [Feynman's italics.]

There I don't understanD ,the time becomes Space ????

I need a concrete explaination about the general relativity and its ten equations .

I rather d like say ,the space becomes mass ....the Dark matter .

On the other sisde ,The dark energy don't exist in my opinion .The expansion is just a step of perception ,correlated with our evolution .Thus the infinity is just behind our walls .

Sincerely

Steve

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You know Mr Smith ,I liked a lot your essay and your skills,this thread is one of the most relevant with your discussions with Mr Jonhstone .

Personnally ,

I don't understand why people want travel in Time .Or to find some datas about that .

If our entropy ,this creator and its multiples names ....has created the mass in a space with a time constant .Thus our rule is to accept our limits .

The fact to want travel in Time has no sense for this equation .

Even for the future ,because we must accept this constant of evolution where he builds in fact .

If we take,for exemple, an actual polarised system like us ,a human ,thus adapted with its environment since 15 billions years .

Let's imagine now a travel in the future with our characteristics ,we are going to be in an other system where the system are more evolved thus our adfaptation will chaotic ,thus it's not necessary and furthermore dangerous ,that's why for the ultim entropy ,it's impossible .It's not in the fundamentals of the ultim equation in my opinion ,thus it's not his choice in fact .

Thus it's a lost of time.

Respectfully

Steve

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It's the same problem with the deseases ,when we accelerate their evolutions ,it's chaotic like actually on Earth and the factors of mutation .

Some human systems ,unfortunally ,accelerate their evolutions.....

The time is really a constant to harmonize in my opinion .

Regards

Steve

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I would like to refer back to my post of Sep. 22, 2009 where I talked about the lack of proofs of the impossibility of time travel and perhaps state more strongly why Mr Smith's main essay premise is important. The statement that "a particular time is identically equivalent to, and is completely defined by, and only by, a particular configuration of the universe" *does* supply a potential proof...

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I would like to refer back to my post of Sep. 22, 2009 where I talked about the lack of proofs of the impossibility of time travel and perhaps state more strongly why Mr Smith's main essay premise is important. The statement that "a particular time is identically equivalent to, and is completely defined by, and only by, a particular configuration of the universe" *does* supply a potential proof and falsifiability, as Mr Smith has mentioned. The essential point is the fundamental difference between this model, with the equally important additional condition that any "particular configuration" only exists *once*, and the "block spacetime" model of General Relativity. In GR, the configurations (objects/sub-systems) are considered to be moving through a "pre-existing" spacetime with evolving 4 vectors, one coordinate of which is "time". The Einstein equations can then allow a metric solution which enables an object's trajectory F(x,y,z,t) to "transform" to a "past" coordinate frame. In Mr Smith's model, this cannot happen as there is no "pre-existing "spacetime".

The GR timeloop, wormhole etc solutions of course rely on there being a "time" coordinate. Remove this and you are just left eg, with a space-like loop, which can make sense in the context of some known relativistic effects. There seems no doubt however that, as I stated very early on in this comment thread, the world cannot be described with only 3 dimensions. The question is, what exactly is the nature of the 4th dimensional quantity? This relates directly to Paul Valetta's questions.. "can you travel anywhere without Time? can anything in the Universe, move from one location to another, without the concept of Time". I think it is very telling that he uses the word "concept" in his second question. We seem to be trapped in the confines of our own use of the word TIME, a la John Wheeler! I think we are also trapped by the "ingrained" concept of "time" that our reliance on clocks has imparted, so that we believe clocks are actually measuring something we *call* time. Clocks are just physical systems we have designed with reference to cyclical processes (Earth's rotation, Caesium atom oscillations), to give us information about those same *spatial* cyclical processes, ie spatial displacement.

In response to Paul I would say that, yes, we need to be able to define what it is that "allows" motion and that can fully describe an "event", to use conventional terminology. All I am saying is that it should be defined in terms of the only things we have, space, motion and mass/energy. Motion from place to place can be described as simply a re-distribution of energy. If the motion is inertial it will be symmetric with any other inertial frame with the usual effects caused by relative motion, but no "time dilation" effects. If the motion is accelerated or spatially asymmetric, an asymmetry results in the subsequent frames which results in the effect called time dilation, but which I think should be reinterpreted only in terms of the space/length "contraction" which is also an implicit effect, but one which tends to be overlooked in most explanations.

Mr Smith has quoted Feynman's belief that time quantities probably should be spatial.."time is space". There have been other prominent physicists who have also hinted at this. Stephen Hawking in "A Brief History Of Time" (I think?) also talks about converting time to space (using Wick rotations in the complex plane), to simplify equations. These solutions can then be converted back to time *if convenient*. As previously discussed here, an "evolving configuration space"(ECS) model could use some differential between vectors in a configuration space where the 4th vector may represent relative motion/velocity? Think of it firstly in conventional terms where motion along a particular spatial dimension, say X axis, is inversely proportional to motion along the Y or YZ axes and motion in "time" seems to be inversely proportional to motion in the 3D "bulk" vector space. So that being static equates to maximum "motion" in time (at c?) and maximum motion in space and/or velocity at or near c equates to being static in time. In the "ECS", the 4th vector could be considered to be orthogonal to the usual 3D's when maximal, with an angle "measuring" the relative motion at other velocity differentials?

Buzz's question..."What is the duration of Present Time?" is absolutely a good one! It goes to the heart of our perception of the world and how our consciousness shapes our understanding of reality. We have evolved to "sense"

time durationally and as a continuum. This is somewhat incongruent with the physical laws we use which are based on the world being *discontinuous*, ie quantum in nature. We quantise everything, the very nature of measurement implies that it is quantised. I would agree with Mr Smith that these "senses" are an evolutionary trait, presumably to aid in our survival. In the absence of any sensory input or in the absence of any motion in the world, I believe we would still have the sense of duration, so I don't think we can trust that sense to develop any description of reality. Attempts have been made to also "quantise time", so far, to my knowledge, without success. Peter Lynds may have developed a kind of proof that it can't be done, even in principle! What does this tell us? If we are to believe that nature is inherently discrete (again quantum gravity pending) and that time cannot be quantised, where is time??

Cheers all

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At the risk of repeating myself, well said, and thank you, Mr. Johnstone! Your insightful comments are deeply appreciated. You are describing and explaining my ideas much more coherently than I possibly could. I somehow almost have the feeling that you are an "alter ego," and, fortunately, one with a far better grounding in the intricacies of physics.

One thought regarding your final comments about quantizing time: if it is true, as some, including Feynman and others, have suggested, that "time" should be "measured" and/or expressed in units of spacial displacement, and if the Planck length represents a smallest possible measure of displacement, might that somehow lead to a quantization of our ability to describe increments of time?

This is fun and exhilarating stuff, imho. I'd like to think that, collectively, we're zeroing in on a better mousetrap in terms of a better explanation for our observations about our world. I've long been convinced that the currently prevailing conventional way of thinking and talking about time has been an impediment to progress in physics. Replacing it with some sort of relational, Machian alternative almost certainly would be a worthwhile step forward. So damn the torpedoes! Full speed ahead!

Cheers all, indeed!

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Hi both of you ,

Interesting explainations .

Sorry but Mr Smith I don't understand all ,you use specific unknow words for me .

Mr Johnstone you say "Where is time"

Simply everywhere since the beginning to build and for that a constant of building is essential .

The time don't need to be quantised for me , a constant is a constant like the speed of light .

Without time,any evolution is possible .

Space without time hasn't any motion .Time without space hasn't any rule .

Of course everybody has its own perception of things .

"Feynman's belief that time quantities probably should be spatial.."

I don't agree but it's personal of course .Because we can check the space and not the time simply .

It's more interesting to check the space and that to discover our Universe ,we are voyagers and catalyzers inside a beautiful sphere in evolutuion .

Best Regards

Steve

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Mr. Dufourny,

You wrote,"Sorry but Mr Smith I don't understand all ,you use specific unknow words for me ."

What word(s) did you not understand? If possible, I'll try to clarify.

jcns

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Hello dear Mr Smith ,

It's ok I have translated .I understand better your point of vue .

Your special relativity is relevant .

I need time to encircle all in fact ,as it's not my first language ,sometimes I search the real message .That depends the kind of writings .

I evolve fortunally .

Best Regards

Steve

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Steve,

You said..."The time don't need to be quantised for me , a constant is a constant like the speed of light." It should be remembered however that light itself *is* quantized. It consists of photons (quanta) and it is the photons which travel at the speed of light, not necessarily the light "ray" itself. I would ask you how the speed of light is measured? Speed has dimension of time...

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Steve,

You said..."The time don't need to be quantised for me , a constant is a constant like the speed of light." It should be remembered however that light itself *is* quantized. It consists of photons (quanta) and it is the photons which travel at the speed of light, not necessarily the light "ray" itself. I would ask you how the speed of light is measured? Speed has dimension of time (d/t) and I would say it is measured with the denominator being determined in exactly the same way that we measure time in all cases, by clocks!

ie c = 300,000 km/sec. One second is simply 0.0041666 of 1 degree of the Earth's rotation, nothing more! It (c) is therefore a measure of two relative displacements. We can only ever measure motion with reference to some other motion. If this is not the case and you want to use time, then I would ask you, at what rate does time flow?

Mr Smith raised the excellent question..."if the Planck length represents a smallest possible measure of displacement, might that somehow lead to a quantization of our ability to describe increments of time?" I would say firstly that my overall conclusions about the "disappearance" of time (and everything else?) below the Planck scale can be boiled down to the lack of being able to resolve anything physical at that scale, eg anything smaller than the shortest wavelength (10^-33cm?) cannot be resolved/measured. This means there is no physical observable and certainly no possible spatial displacement that can be used to "quantify" time. Then I would say that, again, the notion of Planck time ie 10^-43sec is also based on a clock reading of a photon travelling the Plack distance, 10^-33cm, while the Earth rotates 10^-43x0.0041666 of a degree, so that we still have only quantized space. We are still only left with the ability to describe increments of spatial displacement.

It is worth noting in this context that there has been some work done in recent years to investigate whether there is/should be a "minimal length", independant of the Planck length. This is motivated by the possible violation of Special Relativity due to Lorentz contraction in quantum field theory implying sub-Planck contraction and therefore a bit of a paradox! Models proposed to address this such as "Deformed Special Relativity" & other modified SR theories are being developed as we speak. Who knows where that will lead, or if it is in fact a problem at all?

These are only my thoughts and, as time has been one of the great mysteries to have troubled the greatest minds for millennia, your description or explanation of time is as good as mine, or anyone's for that matter!!

Cheers

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Mr Smith,

Just thought I would let you know that I have just finished reading the first of the Smolin papers you cited previously and, whilst I think I will need to read it again to fully understand the implications, I believe it does relate to your configuration/time equivalence idea, albeit from a different standpoint. He seems to be talking about the difference between quantum & classical formulations using the full space of possible states & his idea of a finite procedure using only an initial state then evolution only involving a finite set of possible "successor" states, ie a finite sub-space of the total(infinite?) space of all possibilities. This would seem to equate to some extent to the difference I have mentioned between the GR total "block" spacetime of all possible states & your evolving configuration model, where any initial configuration would only have a finite set of possible "successor" configurations.

What I don't quite get from his paper yet, and the reason I want to re-read it, is precisely why time is "necessarily" introduced in his procedure, and even if it is, how it really differs from the usual quantum mechanical use of a time operator on the evolution! The paper does also seem to raise a similar issue to one I have raised previously regarding whether the total space of possible configurations must be infinite or not?

By the way, if you have a spare moment, can I suggest you have a look at a comment (the whole thread is worthwhile!) posted on the discussion thread under Forums titled "Demystifying wave function collapse" initiated by Garret Lisi. The comment is by Gevin Giorbran dated Dec. 23, 2007. Is it just me, or is he describing almost exactly the same type of model as we are? He even seems to talk about the same "tension" between our conscious sense of time & reality being "linear" as a continuum on one hand and reality being quantum, that I have raised previously. He also seems to imply a similar sort of 4th dimensional space that I have (vaguely!) proposed.

Note in particular the fourth paragraph and, eg "this fourth dimensional space is dependent upon change, it is dependent on objects having unique positions relative to other objects"! Not sure what he is really saying about motion though?

Would appreciate your thoughts!

Cheers

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Mr. Johnstone,

I'd be more than happy to look at the Lisi thread you mentioned. Thanks for calling it to my attention. Have not heretofore been following it. Could you please be so kind as to provide a direct link to its starting point? (My very cursory scan of the horizon failed to bring it up.) So many threads, so little time. Yikes. Inasmuch as it dates back to Dec '07 and earlier, it will take me a while to get caught up!

Much of my time of late has been devoted merely to staying abreast of the new essays being submitted to the competition, many of which have been very interesting in their own right. Suspect that the pace of submissions may accelerate as the deadline for new submissions draws nearer.

And I'll need to go back and re-read that Smolin paper to refresh my own memory on it before attempting a specific reply to the issues you mention. Just in general, however, yes, I'm intrigued by any rigorously developed schemes in which only one actual "history" of the universe emerges (evolves) as an objective reality from some (arbitrary?) initial state. The Laws/Rules of Nature/Physics apparently dictate the course of this evolution. Our task, as observers of this evolution, is to ferret out those Laws/Rules.

As for why time is "necessarily" introduced, it would be my hope that any "time" introduced in such a scheme would be our much sought after "Machian" relational variety of time rather than the old, traditional, now thoroughly discredited (in my opinion) "clock" time.

Yes, we will always need something which we'll call "time," but it should better reflect the reality of the universe than does clock time, i.e., it should reflect the notion that particular times are defined by particular configurations of the universe and that "the flow of time" consists of the evolution of those configurations. Clock time involving our traditional units of hours, minutes, seconds will continue to be useful for arranging our dinner engagements and organizing our car pools and our general day to day lives, but it will no longer be useful (or at least will not comprise, by default, the "be all and end all" of our notion of time) in our probing of the rules whereby we understand the workings of the universe.

It frustrates me greatly that I've not personally been able to get a handle on what needs to be done to accomplish this goal (my just deserts for a misspent youth and career devoted to studies other than physics). That's why I fervently hope that the Smolins and Barbours and Johnstones of the world will nail this elusive bowl of jello firmly to the wall once and for all, and that this will be done during my lifetime. I do have a sense that some very smart people are zeroing in on it. I remain optimistic. And I believe that, once done, it will allow us to surmount many of the currently intractable puzzles of physics. It's worth the candle.

Cheers

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Dear Roy Johnstone,

On Sept. 29 you wrote: being "linear" as a continuum on one hand and reality being quantum. What sort of continuum are you referring to? Peirce or Hausdorff?

As an engineer I need a Peirce continuum in case of incommensurables and non-linear functions,

see the chapter "How to cope with what is behind Cantor's paradise?" in my new essay.

Regards, Eckard

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Mr Smith,

Direct link to Garret Lisi's "Wave Function Collapse demystified" is -

http://www.fqxi.org/community/forum/topic/39

What really got me interested in it was that the very first response was from Dieter Zeh, developer of the theory of "quantum decoherence" !

Cheers

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Eckard,

I am not familiar at all with a "Peirce" continuum, so you are one up on me! The point I was making is simply that our conscious sujective perception of physical processes and of "time passing" is continuous, which is in contrast to experimental observations of the objective world being discontinuous, ie quantum in nature (Quantum Gravity pending?). So it's a bit like a movie with the frames as the quanta (objective), but we only "sense" a continuous image (subjective).

To answer your question more directly, I would say that the continuum I have in mind could be considered to be a "densely ordered" Hausdorff continuum but, as a layman, I would welcome any light you could shed on the application of various classes of continua to these matters!

NB. If you have read all of this discussion thread, you will probably realise that both myself & Mr Smith consider that what we sense as "time passing" is nothing more than the physical change from one relative configuration to another.

Cheers

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Mr. Johnstone,

Thank you for the link to the Lisi thread; it does look interesting. I'll plan to wend my way through it from beginning to end, as time allows. I agree that having Dieter Zeh as the first to comment would catch one's eye!

I looked at Gevin Giorbran's post of Dec 23, '07. Yes, he clearly is grappling with some of the same issues we've been discussing. I find myself...

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Mr. Johnstone,

Thank you for the link to the Lisi thread; it does look interesting. I'll plan to wend my way through it from beginning to end, as time allows. I agree that having Dieter Zeh as the first to comment would catch one's eye!

I looked at Gevin Giorbran's post of Dec 23, '07. Yes, he clearly is grappling with some of the same issues we've been discussing. I find myself returning to Barbour's discussion of the Machian Distinguished Simplifier (pp.119-120, TEOT). That's certainly one of the clearest descriptions I've seen of the sort of configuration space that I believe we're striving for.

Then I go back to Barbour's discussion of the Kingfisher (pp. 264-267). Here, Barbour is again addressing some of the sorts of issues raised by Mr. Giorbran. Please look at the last sentence of Giobran's first post of Dec 25, 07 where he writes, "The present configuration of the universe cannot ignore all the equally possible futures and dictate a single future, because the equally possible futures are equally real (and our universe is a sampling of that reality)." Compare this with Barbour's statement, "There are infinitely many possibilities, and they are all there. They must be, since there is a place in Platonia for everything that is logically possible." (p. 267 TEOT) This bears on the issue you've raised ("whether the total space of possible configurations must be infinite or not?") in your post of Sep 29, '09 and elsewhere.

My own intuition on this is that if we succeed in correctly cracking the code of Nature's Laws, any initial state of our configuration space will lead to no more than one objectively real "history" of the universe. Which is not the same as saying that this history need be purely deterministic, per se. But, if I correctly understand Barbour's view, I disagree with his assertion that there must be a place for "everything that is logically possible." This requirement to have a place for everything logically possible goes away because the Laws of Nature will dictate which of the many logically possible configurations will actually evolve, i.e., become objectively real. Those potential configurations that do not become objectively real are then not an issue. It does not seem reasonable to me that they somehow take on a status of being "real" (in some mysterious quantum sense) "alternate/parallel universes."

As an aside, earlier in Giorbran's post of 23 Dec, '07, he alludes to the notion of "insurmountable infinities." By this I gather that he's referring to a concept similar to Zeno's paradox of Achilles and the turtle? If so, this paradox can be easily dispatched by our view of time. The race between Achilles and the turtle comprises but a small portion of the evolving universe. There simply is no "time" which is separate and distinct from the evolution of the universe. Once this is recognized, the paradox vanishes.

Apologies for the rambling nature of this post. The hour is late, or early, depending on one's way of thinking about time. Probably not an ideal time to attempt coherent thought.

Cheers

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Mr. Johnstone,

It is dangerous to put fingers to keyboard when one is groggy. In my previous post I was careless in my use of the term configuration space. Despite evidence to the contrary, I do grasp the concept of a configuration space such as Barbour's Platonia. Barbour writes, "Take some point on one of the Machian geodesics in Platonia; it is a configuration of masses. Take another point a little way along the geodesic; it is a slightly different configuration." etc. (p. 119, TEOT) It strikes me that what Barbour is describing here and on the following page is a key to our goal of describing time in terms of configurations of the universe and describing "the flow of time" in terms of the evolution of configurations of the universe. Why does Barbour specify taking a point on "one of the Machian geodesics"? Would there be any other kind of (non-Machian) geodesic?

If I understand correctly some of your questions, you are grappling with understanding and/or devising the rules and methods for describing the way we move from one configuration of masses to another without introducing an external "time" component. (I've not re-read Smolin's paper yet, but I think it may be highly relevant here.) This appears to be a problem intimately linked with Barbour's Machian Distinguished Simplifier concept. In my own way of thinking, however, I would dispense with the configuration space of Platonia and simply look at a "real" configuration of masses. The universe has only one real, evolving configuration. There is only one elephant. We need not begin with a configuration space of all all potential, logically possible elephants. But I ramble. I need a configuration of the universe which includes a cup of coffee in my hand. And I'm able to make that happen! Is this a great universe that we live in, or what?

Cheers

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Hi Mr Johnstone,Mr Smith ,all,

Interesting point of vue .You know I like the works of all here on FQXi ,with different points of vue ,this one is relevant about the relativity .But Of course all people have theirs opinions and perceptions of our Universe and its laws .

We need an international system for our unities I think and fortunally it exists .

I my memmory is correct...

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Dear Mr Smith,

It's well said your words

"Each new configuration of the universe that

we observe represents a new time. And each new

configuration replaces the previous configuration, which

then ceases to exist except as a “memory” or intellectual

concept."

Could you develop a little please ?

And second ,what do you think about the fact what the chaos is in a very very very short time ?

I see the chaos like that a instant like a foto in fact .Let's take all chaotic effects ,it's always like that ,an instant if we take the time line between 13.7 to 15 billions years .

What do you think ?

Best Regards

Steve

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Mr. Dufourny,

Thank you for your kind compliment on my essay. A more detailed explanation of the thinking which serves as background for this essay may be found here. Some even earlier, more detailed thoughts on the topic are contained in a monograph dating back to 1999, which, unfortunately, is not available in electronic form.

I'm afraid that I don't understand your question about "the chaos." Perhaps you could explain a bit more?

Cheers

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Sorry, I thought I was logged in when I submitted that previous post, but evidently not! Or there may be gremlins in the system?

jcns

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hihihi yes perhaps some greemlings ,but you know I prefer the mougwai ,don't give it some water .hihi

About the chaos ,it's very simple ,I see it like a short very short time ,like an instant foto .

Let's take for exemple a gun ,these effects ???

Let's take a human pollution ,it's due to our very short unconscious .

What I say is very simple ,the harmony is universal since the beginning and towards the unification and the chaos is short like a foto of a explosion of a spar ,in fact the star goes to an equilibrium in fact .

Let's take for exemple the fact to kill an insect ,it's the same a short instant to imply the chaos ,the suffering or .....in fact the chaos is just a human invention !

It was my thought about that .

Regards

Steve

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Mr. Dufourny,

Thank you for your helpful suggestion regarding the recommended way to deal with mogwai; I'll make a mental note of it. When in China I'll refrain from giving them water, but when in Scotland I think it might be more efficacious to refrain from giving them Scotch.

Regarding your thinking about the chaos, I cannot disagree with what you say on that topic.

Cheers

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You are welcome

hhahahha beautiful humor .

Regards

Steve

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Mr. Johnstone and All,

For those who have been following the extended discussion in this thread, I'd like to recommend for your reading enjoyment a newly submitted essay, "The Ultimate Physics of Number Counting," by Andreas Martin Lisewski. If I correctly understand the ideas which Mr. Lisewski is presenting, they have a direct bearing on issues we've been discussing here regarding ways to describe the evolution of the universe. If you have an opportunity to review that essay I'd welcome your thoughts on it. Thanks!

Cheers

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Dear Mr. Smith,

I enjoyed reading your essay. Its intellectual content pushes forward understanding of time in a fresh way. It is accessible to a diverse, highly-educated but non-specialist audience. It treats foundational questions and it is topical, although for this last criterion, it may probably have better suited in last year's contest. I definitely rate it at a level well above the current one.

I like your positive conclusion which makes us actors of our universe (and not just observers). I also appreciated the fact that you invoke only physically sound arguments, without confusing the reader with theoretical considerations and space-time paradoxes. This helps to focus on the fundamental reality of "Time". I'm essentially on the same line of reasoning as you. For my own research, I adopted Aristotle's "Time is the number of change", which is appropriate for quantum mechanical time. The definition you propose of time is a statical one: a particular time is one configuration of the universe, unrelated to the preceding times. Have you also tried to define the succession of configurations ? If a particular time is one configuration of the universe, then only one other configuration that precedes it. For example, a dynamical definition could be: a particular time is identically equivalent to a particular configuration of the universe evolving out of the sequence of preceding configurations.

By the way, I collect quotes of the essays I've read. Would you mind if I publish some of yours on my twitter profile and blog, linking of course to your essay ?

Regards,

Arjen

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Mr. Dijksman,

Thank you for your positive comments on my essay. To answer your last question first, I'd be delighted if you saw fit to quote from my essay. It would be a great honor for me.

Regarding your comments about the static vs. dynamic nature of my definition of a particular time, you are of course correct. The thread which accompanies my essay is a lengthy one, and there is so much for us all to read now with so many new essays being posted, but there has been a spirited ongoing dialogue about the best way to describe time in a dynamic universe without invoking an external, classical, "clock time" in the process of doing so. What clearly is needed is a Machian, purely relational way of describing how the universe evolves, i.e., moves from one configuration (particular time) to another. Unfortunately, this is not as simple as it sounds. As always, the devil is in the details. I am not a professional physicist, so am hoping for and welcoming ideas/suggestions/inputs from those better grounded in the science to help develop the necessary, scientifically rigorous procedures to achieve this goal.

Of course, Julian Barbour is a great authority on this topic, and his ears must be burning from the number of times his writings have been quoted during these discussions. Unfortunately, in his book 'The End of Time' Mr. Barbour argues for a static universe, a concept with which I have not been able to agree. I understand that he will soon be publishing an update to that now 10-year-old work. I can only hope that during those 10 years he has perhaps "seen the light" about the need for a dynamic universe, but judging from his other more recent writings I am not holding my breath on that score.

Cheers

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Dear Roy Johnstone,

Since you apparently did not submit an essay, I would like to suggest we continue our discussion here .

You wrote:

I am not familiar at all with a "Peirce" continuum,

-- Peirce defined a continuum as something every part of which has parts.

The point I was making is simply that our conscious sujective perception of physical processes and of "time passing" is continuous,

-- I disagree.

which is in contrast to experimental observations of the objective world being discontinuous,

-- I consider continuity and discreteness mutually complementing ideals.

To answer your question more directly, I would say that the continuum I have in mind could be considered to be a "densely ordered" Hausdorff continuum but, as a layman, I would welcome any light you could shed on the application of various classes of continua to these matters!

-- Hausdorff belongs to set theory. You might find my position explained in the essay of mine.

NB. If you have read all of this discussion thread, you will probably realise that both myself & Mr Smith consider that what we sense as "time passing" is nothing more than the physical change from one relative configuration to another

-- While I was unable to read all, I agree that so called nature permanently changes and elapsed time is a measure of the resulting length of the causal chain between two events.

Regards,

Eckard

Cheers

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Mr. Smith,

With respect to a dynamical time, I think a correct way to think of it is what we already do with Cesium clocks. When a particular system emits a photon, its state vector (arrow or hard rigid needle or any image we may have of it) rotates at an angular velocity which is invariant wherever we are. A definite time is thus given by the angle swept by this arrow (and the configuration of the whole universe at that instant). The photon therefore carries in itself a dynamical measure for time. It is evolving at a rate which may be compared to the evolution rate of any other quantum particle in the universe.

I have posted a quote of your essay on twitter (you may find it by googling for twitter and my name). There will come others this month. Thanks.

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Mr Smith,

I hope you enjoyed that cup of coffee the other night and, yes, it is a great Universe that we live in! But is it the only one?

Barbour's "Platonia" is a quantum cosmology theory. It is based on a Wheeler-De Witt type universal (static) wave function so that his "logically possible" configurations/states would presumably be all other "possible" eigenvalues represented in the wave function amplitudes. He then constrains the "observed" eigenstates to represent "time capsules" as solutions to the wave equation, ie his "blue mist". Your equating of this with Gevin Gorbran's "equally possible futures' is probably close to the mark. Everett's "Many Worlds" gives dynamical reality to *all* of these superposed eigenstates/"possible futures" in branching universes (some with cups of coffee in your hand, others without!). When Barbour talks of taking a point on "one of the Machian geodesics" I think he is just reinforcing that *all* geodesics are Machian, rather than implying that there may be non-Machian geodesics, as that would negate his whole idea.

As you said, in our view of evolving configurations, we take the evolution to be in a finite space of possible successor configurations as per Lee Smolin's quantum gravity "finite procedure", rather than the infinite space of all possible states. This again is essentially the difference between a "block space(time?)" model such as GR or Platonia, with trajectories representing one set of solutions out of infinitely many, and a dynamically evolving space such as ours described by a single trajectory, your "one, real evolving configuration". I believe there is hope for this type of construction coming from QM due to work in the area of Bohmian Mechanics and from Smolin's QG ideas. I must find something more recent from him than the 1997 paper to check his current thinking on this.

I guess what I am grappling with is not so much " understanding and/or devising the rules and methods for describing the way we move from one configuration of masses to another", I think we have physical laws that (mostly) describe that (notwithstanding misleading "time" parameters), but rather the twofold question of a) what is the spatially derived quantity that should replace the time operator/quantity in the equations of those physical laws and, b) what is the 4th dimensional spatial quantity that should replace the time coordinate in the classical relativistic regime?

As for the dispatching of Zeno's paradox by our view of time, I'm not sure that's right. As I vaguely recall, I thought the paradox of Achilles and the tortoise was more to do with increments in space rather than time? I must find a reference to the paradox and familiarise myself with it again. I am also yet to read the 2nd of the Smolin papers you mentioned and I will also read the Lisewski essay as you suggested. Phew!! As you have said, so much to read, so little time!(Oh no, there's that "t" word again!!).

Cheers

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Eckard,

I will certainly read your essay as soon as I can.

Please note, the web page would not load from the link you provided.

Cheers

Roy

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Mr. Johnstone,

Thanks for your good reply/comments! I'm "on the run" at this moment, but wanted to let you know I appreciate your post, which I will take more time to review carefully later, and I also wanted to recommend another interesting recently posted essay to your attention (not sure if you're trying to read/scan them all; I am). One with which I do not necessarily concur, but which I believe particularly noteworthy for spelling out divergent views on a topic of interest is, 'The Possibility of Unification via a Global Adynamical Organizing Principle' by Michael David Silberstein. I've posted a comment in the thread of the essay in which I put in a word for our approach. Never a dull moment!

Cheers

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Mr. Johnstone,

Have been out enjoying a beautiful autumn day. A good way to reconnect with the universe.

Regarding Zeno's Achilles and the tortoise paradox, if we can believe the interpretation on Wikipedia (not sure how big an "if" this is, but I've typically found it a good first order approximation) we have slain this paradox (see http://en.wikipedia.org/wiki/Zeno's_paradoxes ). I'll gladly take my small victories anywhere I can find them.

Cheers

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Mr. Johnstone,

You wrote, "I believe there is hope for this type of construction coming from QM due to work in the area of Bohmian Mechanics and from Smolin's QG ideas. I must find something more recent from him than the 1997 paper to check his current thinking on this." In this regard, I was referred by another essay author (Jonathan J. Dickau, who, btw, appears to be a "fellow traveler" of sorts regarding being on board with, or at least not vehemently opposed to, some of the ideas we've espoused), to a highly relevant paper by Fotini Markopoulou, who of course has been working closely with Smolin on quantum cosmology, so perhaps her paper might give some hint as to his more current thinking? You will find her paper here: http://arxiv.org/pdf/gr-qc/0210086v2 Sorry to add to your already long reading list (but not *too* sorry; you did, after all, more or less ask for it)!

Cheers

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Roy,

Thank you for your hint. I misspelled the link to this.

You may skip the inner ear matter. I considered it worth to make more public how Ren demonstrated that a theory can ultimately be wrong even if it was abundantly confirmed by many experiments and earned a Nobel price.

By the way, why did Alfred Nobel decide against establishing a Nobel price for mathematics? He disliked Leffler-Mittag who was a supporter of Cantor's set theory.

Please vote for ultimate realism too.

Regards,

Eckard

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Mr. Johnstone,

You wrote, "I hope you enjoyed that cup of coffee the other night and, yes, it is a great Universe that we live in! But is it the only one?"

Just for the record, I'm firmly in the Smolin/Markopoulou camp on this score. I like the slogan proposed by Smolin in 'Three Roads to Quantum Gravity': "One universe, seen by many observers, rather than many universes, seen by one mythical observer outside the universe." (P. 48) My own admittedly less elegant paraphrasing might be something along the lines of, "There's only one elephant."

Cheers

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Mr Smith,

If you haven't already pounced on it, Peter Lynds has submitted an essay which typically is very heavy on the issue of time. Note in particular part 3!

Cheers

Roy

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Mr. Johnstone,

Thanks for the heads up. I'd been reading the essays in sequential order so as to minimize the chances of inadvertently overlooking any, but on your recommendation I jumped ahead to Mr. Lynds' essay, which was, as you said, heavily into topics of interest to us. Also of interest, of course, is G. F. R. Ellis's essay. Now, back to the reading! Unless any additional essays trickle in, my latest count was 113 total.

Cheers

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Greetings J.C.N.,

It was a pleasure reading your essay. I'm not entirely certain it addresses the question of what's possible to know from/with Physics, but it was an interesting excursion into a subject worthy of exploration. It seems your main point is that each configuration of the universe is unique, and that therefore "if we weren't a part of it, when it was happening, we can't go to the past" and "since it hasn't happened yet, we can't go to the future."

To some extent, this does involve questions about what is knowable in physical reality, so it is perhaps germane to the discussion of concepts for this contest. I too have concerns about hidden assumptions that are endemic misconceptions about time. If time is not a variable, but a progression of 'configurations of the universe,' this does put a different slant on things. On some level, this begs the question of whether your argument can be turned inside out, though, so that your statements become a method for time travel instead.

As luck would have it; the answer which emerges therefrom is articulated by Don Juan to Castaneda, in one of the latter's books (I don't remember which one). Juan suggested to Carlos that if he wanted to transport himself, the way to accomplish this was by creating a new assemblage point - a new place to 'assemble the world' from. Specifically; he instructed Carlos to unmake the world of his origin point, and assemble the world of his destination - rather than transporting himself per se. The idea was to let go of one configuration of the universe, and latch onto another.

Of course; this is all rather fanciful, but if it could be made to work, it would apply equally well to moving through either, or both time and space. And it incorporates your insight of a moment in time being represented by a particular configuration, an assemblage of particular qualities and quantities which allow us to identify a given time and place unambiguously.

I've seen no evidence this is anything but fiction, and I have no idea how this mode of transportation can be utilized, in practical terms, but I note that a similar conceptualization is employed by you and Castaneda. It would seem that what you propose is impossible, however, is exactly what he has set out to explain how to do.

So; perhaps yours is not an air-tight argument, after all. Any thoughts on this?

All the Best,

Jonathan J. Dickau

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Mr. Dickau,

Thank you for your comments and questions. First, to address your question regarding whether my essay falls within the theme of this year's competition, the theme deals with "what is ultimately possible in physics," with a related aspect being "what is ultimately IMpossible in physics." This was made explicit in the evaluation criteria, which I quote here:

"What role do 'impossibility' principles or other limits (e.g., sub-lightspeed signaling, Heisenberg uncertainty, cosmic censorship, the second law of thermodynamics, the holographic principle, computational limits, etc.) play in foundational physics and cosmology?"

In this light, an essay dealing with the impossibility of time travel strikes me as being well within theme's boundaries. As to whether my position is falsifiable or not (i.e., whether it is science or not), it is. All one need do to falsify it is to demonstrate conclusively that time travel of the variety portrayed in science fiction *is* possible. But there are also other, simpler, potentially actually achievable approaches to falsifying it as well; these are discussed in reference 4 of my current essay.

Now, having hopefully put that issue to rest, I'm delighted to address the very excellent and interesting story of Don Juan to which you alluded, because it is very germane to my argument regarding time. Thank you for bringing it to my attention. I'd not heard of it before, but now I'll plan to look it up to read in detail.

If I'd done a better job of writing my essay and explaining more clearly my argument, it would have been immediately clear to you exactly how the Don Juan story (as you've summarized it) actually serves as an illustration of the concept I'm trying to convey. Configurations of the universe are what it's all about. For example, Hollywood film-makers manage to "re-create" visual impressions of bygone eras by "re-creating" in carefully controlled environments the configurations of whatever era they're trying to portray in the film. If the film is about Al Capone, they drag out all the old cars from museums and all the period clothing and use them to re-create a small configuration, in the confines of a sound stage or elsewhere, which mimics a small part of the configuration of the universe as it existed during the gangster era, or whatever other era they're trying to re-create.

All the "stuff" in the universe always has some configuration, i.e., some arrangement, which is constantly changing, i.e., evolving. We are all perpetually and unavoidably "letting go of one configuration of the universe and latching onto another." We have no choice in the matter. It's an inevitable consequence of being ourselves parts of the evolving universe. In this sense, and in this sense only, we are all time travelers. We are all continually making new "assemblage points" for ourselves, whether we want to or not and whether we know it or not; we are continually burning some old bridges and building some new ones. But we're basically always just shuffling around the same stuff from one place in the universe to another. As in the Don Juan story.

If I've still failed in giving a sufficiently clear explanation of the point I'm trying to convey, please don't hesitate to ask for further clarification. I'll be happy to give it another try, as needed. And thank you for the lead to the Don Juan story!

Cheers

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Mr. Dickau,

As an addendum to my previous post, I'd like to amend one image which I offered there. Rather than the image that we're "continually burning some old bridges and building some new ones," I think it's more helpful to say that we're continually "selectively using parts of old bridges to assemble newer ones." And this is more in line with the image in the Don Juan story, "Specifically; he instructed Carlos to unmake the world of his origin point, and assemble the world of his destination . . . ."

Perhaps the best way to get an intuitive "feeling" for my concept of time is to simply ask yourself what makes today different than yesterday. In the final analysis, I believe that the only satisfactory answer is that the configuration of the universe is different. I believe that any other answer to that question which we might propose ultimately boils down, in one way or another, to being merely another way of saying that the configuration of the universe is different.

Most, but not all, of the ways in which the configuration of the universe will evolve from today forward are beyond our control. But chaos theory, a la the butterfly flapping its wings in China and thereby unknowingly contributing to initial conditions which ultimately lead to a hurricane in Florida, suggests that we should not underestimate our influence on future configurations of the universe. Unfortunately, most of the long-term consequences of our actions and/or lack of actions are nearly impossible to predict, leaving us in the position of doing our best to use the tools at our disposal, in the form of our understanding of the laws of Nature, to ascertain and implement actions which are as constructive as possible toward whatever long-term goals we have.

Cheers

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Hello again,

Thanks for the thoughtful attention to my comments. I have read your response. I may return to this page for more insights. Nothing more to say right now.

Good Luck,

Jonathan

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While thinking about the example mentioned in an earlier post about how film-makers create illusions of returning us visually to bygone eras, another example came to mind which far better illustrates the nature of time.

It is a relatively simple matter to re-create realistic outdoor settings for films of the "western" genre (formerly known as "cowboy movies" and more recently as "spaghetti westerns"), which are intended to replicate the American "wild west" of the 19th Century. All one needs is a barren desert landscape, some horses, some tough-looking, well-tanned, leathery-skinned humans (a la Clint Eastwood and Lee Van Cleef in 'The Good, the Bad, and the Ugly'), and some period clothing and accoutrements. Because the visual "essence" of these key ingredients has not changed appreciably since the 19th Century it is relatively easy to re-create an extremely realistic replica of that era.

The illusion thus created would be immediately destroyed, however, if we were to notice an obvious contrail of a jet aircraft in the sky. Contrails of jet aircraft are not part of the set of configurations of the universe which defines the 19th Century. This or any other anachronistic detail tells us instantly that the scene is not what it purports to be. Our subconscious minds know that particular times are identically equivalent to, and are completely defined by, and only by, particular configurations of the universe even if our conscious minds don't.

Film-makers who wish to portray futuristic settings, on the other hand, are less apt to be tripped up by anachronistic details, because no one knows what the future is "supposed" to look like. Items in such films which obviously are throw-backs to times pre-dating that portrayed in the film can be explained, if need be, as antiques or relics from the past.

Cheers

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"Hostage photos" (i.e., photos of people who are being held hostage by criminals) are another illustration, albeit a grim one, of the nature of time. As a way to prove that a hostage was still alive as of a certain date, criminals occasionally make available photos of the hostage. Do the photos typically show a hostage holding up a calendar or a clock? No, of course not, and why not? Because calendars and clocks, per se, have very little to do with defining and identifying particular times. Hostage photos typically show a hostage holding up the front page of a newspaper, thereby placing the hostage in the context of some known broader configuration of the universe. (Of course, due to the availability of technologies such as "photoshop" it is now a relatively simple matter to fake images, i.e., older images could have a more recent image of a newspaper "photoshopped" into them.) The point of this illustration, however, is simply to emphasize that in order even to begin to identify a particular time it is necessary to have some information about a corresponding configuration of some known portion of the universe.

jcns

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Agreed.

Your comments make perfect sense. Whether this 'proves' somehow, that time travel is impossible, is still at issue. The point of the argument could be reversed by stating that it's exactly what any science fiction time traveler would say.

One could imagine Dr. Who, perhaps, turning to his companion as they exit the TARDIS, and saying "In order even to begin to identify a particular time it is necessary to have some information about a corresponding configuration of some known portion of the universe."

Have a great day!

Jonathan

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Mr. Dickau,

You appear to be headed in the correct direction with your thinking about time. Unfortunately, however, you are not yet taking into account several insurmountable difficulties which will continue to rule out time travel. First of all, in the broadest, most rigorous sense, particular times are defined by particular configurations of the entire universe, and the configuration of the entire universe is intrinsically unknowable. I discuss this problem in reference 4 to my current essay, which may be found here. If you've not had an opportunity to read it yet, I hope that doing so, as your time allows of course, may help clarify this point.

Just as a thought experiment, let us assume, purely for the sake of argument, however, that we could somehow miraculously overcome this problem. In other words, let us assume for the sake of argument that we *could* somehow know the configuration of the entire universe. This configuration would define a particular time. Next, since this is a thought experiment, let us further assume that we are even able miraculously to have complete knowledge about how the entire universe is evolving in real time. These evolving configurations are the flow of time.

Now, suppose for example that you want to "travel" from the time in which you find yourself now as you read this sentence, i.e., from the configuration of the universe which, roughly speaking, defines "today," to the configuration of the universe which defined the time of last year's Super Bowl game. How would you propose to actually *do* that, in practical terms?

The configuration of the universe which defines the time of last year's Super Bowl game was dramatically different from the configuration which defines today. To somehow "return" to that earlier time you would need somehow to physically return *all* of the many bits and pieces which comprise the universe to the precise configuration which they had during the Super Bowl game. This is not a trivial task. I would even venture out on a limb and say that it is an intrinsically impossible task.

The universe is made up of an impressive quantity of "stuff," much of it in the form of rather large and massive aggregate objects such as stars and planets. We do not rearrange these large, massive objects to suit our whim the way we rearrange our living room furniture! But this sort of whimsical rearrangement is exactly what would be necessary to make time travel feasible.

I hope this helps clarify my point.

Cheers

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Hello again,

Yes I did read your wonderful essay Time Illusion and Reality. And I think I understand your point.

Allow me to summarize:

1. A moment in time is only fully described by the configuration of the universe, which though perhaps not knowable in its entirety, does have a unique state or description.

2. The flow of time is associated with the evolution of the configuration of the universe. That is; the progression of moments in time is defined by the changing configuration of the universe.

3. Owing to the fact that it is a progression with antecedents and products for any event or configuration, it may be possible for the universe to occupy any configuration only once.

4. It may be impossible to ever assemble the energy needed to bring things back to where they were, even if we could know the complete and exact configuration at an earlier time. And to go to the future this way, we would need to know its exact future configuration - another impossibility.

One could add:

5. If we were somehow able to put ourselves in the picture, it would not be the same universe as that specific configuration - without us. So even if the other objections could be handled (doubtful perhaps), you have not traveled to the past or future precisely - instead you are by default on another timeline. This I see as your 'trump card.'

Nonetheless; I see it as a proof obtained by clever definition of terms (which exclude other interpretations), rather than one which spells out the fundamental limits imposed by nature. Ari Stophrenic's essay on The Non-existence of TOEs suffers from this flaw, perhaps in greater measure than yours. He also excludes the possibility of knowing and predicting the universe's exact configuration, through logic.

But both his proof and yours make me wonder about their value. Are they more than enjoyable mental exercises? I do not know for sure.

Warm Regards,

Jonathan

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An afterthought;

In a comment on my paper, Uncle Al (Alan M. Schwartz) remarked that Quantum Mechanics treats G as negligible (equals zero), while Relativity treats h as non-existent. He also put c in the mix, for some reason, and it got me thinking.

We would set c=0 when speaking about a single instant in time, because if there is no time for a photon to travel in, it is as though light is infinitely slow. Perhaps setting the speed of light to zero would allow some sort of state equation to be crafted, for the universe at any instant.

Is that Wheeler-DeWitt? I'd need to think about it more, but not now.

Regards,

Jonathan

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Bravo, Mr. Dickau! You have indeed done a masterful job of correctly summarizing my thinking; I'm impressed! It is gratifying to be so clearly understood.

As to your question about the value of these ideas, and about whether or not it's all simply an enjoyable mental exercise, I'd of course like to think that it's more than that. I'd like to think that it captures something fundamental about our reality. But your question certainly is a fair one, and one that needs to be asked and answered. The proof of an idea's value or lack thereof must come from testing its predictive power. In this regard, I was gratified that my definition of a particular time leads logically to the "prediction" of the equivalence of mass and energy. But was that simply a fluke? Can that success be repeated and extended? I'm not sure.

As I've noted elsewhere in this thread, I'm unfortunately not a professional physicist, so find myself somewhat frustratingly handicapped in terms of knowing how best to go about "exercising" the ideas, in terms of seeing what they're really good for. Any assistance along these lines from those better grounded in the mind-bogglingly technical intricacies of physics certainly would be welcomed.

As for your question regarding Uncle Al's comment, I can't say anything even remotely intelligent about it, so won't even go there.

Thank you very much once again for being such a careful, insightful, perceptive reader! You made my day!

Cheers!

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So back to the original question which led us down this path: is time real or not? As mentioned earlier, the answer, in my opinion, teeters precariously on one's definitions of the words "time" and "real." In a sense, it becomes a virtually meaningless question, lacking suitable qualifiers. It's not the sort of question which can be satisfactorily answered with a simple "yes" or "no."

Cheers

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As an addendum to my post two previous to this in which I wrote, "The proof of an idea's value or lack thereof must come from testing its predictive power." I'd like to add that one other measure of an idea's value lies in its explanatory power. By this measure, I believe that my proposed concept of time fares rather well.

I've found that "internalizing" this way of thinking about time (i.e., by gradually allowing it to become "second nature" to think of time this way), allows me to explain conundrums which have seemed previously to litter our path in what I've gradually come to regard as "the old-fashioned, conventional way of thinking about time." Examples which spring quickly to mind are paradoxes such as Zeno's paradox of the race between Achilles and the tortoise (which was addressed briefly in an earlier post), and, of course, the various time travel paradoxes generically referred to as "The Grandfather Paradox."

In a broader sense, thinking about time as I propose has helped me simply to put my own observations about the world into what I believe is a more logical, self-consistent, and therefore more satisfying, context. But then I've been thinking in these terms for quite some time. It takes a while to shift mental gears, as it were, and become comfortable thinking this way. As I'm sure it must have taken some serious shifting of mental gears to begin thinking in terms of the Earth not being the center of the universe, for example. But could it be worth it? Time will tell, or not, as the saying goes.

Unfortunately, I fear that shifting gears in this way could not be done without some cost and discomfort. As has been discussed in ongoing discussions between myself and Mr. Roy Johnstone and others in this forum, it is not at all clear (certainly not to me at any rate) exactly how we will do physics if we take these proposed ideas about time seriously. I suspect it might not be a trivial matter to make the needed adjustments. As Lee Smolin suggested in 'The Trouble With Physics,' our thinking about the nature of time got off track (certainly in my opinion at any rate) during the infancy of physics (p. 256 TTWP), and that unfortunate miscue has reverberated in one way or another throughout virtually all of what has followed.

Cheers

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Readers of this thread (especially those who have suggested that time travel is no longer a topic of serious scientific debate) may be interested to read an essay which was published in the science section of the 'New York Times' on 12 October 2009 and titled 'The Collider, the Particle and a Theory About Fate,' and which may be found here. Comments invited/welcomed.

Cheers

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We can not travel in time because time is run of clocks in space. we can travel in space only. In space there is no past, no present and future. They all belong to the mind. Space is timeless.

yours amrit

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Dear Mr. Smith,

You invited to take part in discussion of the term of time.

I agree, true time travel is impossible. However, a clear and direct link between entropy and the so-called "arrow of time" causes interest.

We can examine mathematical descriptions of causality in thermodynamics of irreversible processes. Usually it use with two conditions. a) Consequence cannot precede the reason. b) The small increment of the reason cannot entail an infinite increment of consequence. The second condition does not operate in strongly nonequilibrium (bifurcation) processes. The first condition does not operate in Mach systems. From the point of view of mathematics it makes attractors on a complex surface.

The relativistic thermodynamics has an interesting problem - the relativistic kinematics is not agreed with (quantum) thermodynamics. In my opinion, it enables to start with model of time.

Allow me to offer some steps in this direction.

1. The Relativism determines change of length (anisotropism of space) and delay of time. In relativistic thermodynamics the Law of conservation of energy demands the account of these changes. Anisotropism should be certain as the work of thermodynamic system. This work can be considered as already executed, when systems were accelerated, however the thermodynamics demands its account in the present, thus, we should consider "history" of evolution of system.

2. Relativistic anisotropism can be considered through distribution of energy on degrees of freedom of moving system. Thus, the universal R gas constant is not Lorentz invariant. GR is possibility to check up this assumption, using a gradient of temperature of a solar crown.

If it is interesting, the file is applied.

Yours faithfully,

Alexander Silin.

attachments: Thermodynamics_Silin.pdf

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Mr. Silin,

Thank you for your comments.

You wrote, "We can examine mathematical descriptions of causality in thermodynamics of irreversible processes. Usually it use with two conditions. a) Consequence cannot precede the reason. b) The small increment of the reason cannot entail an infinite increment of consequence. The second condition does not operate in strongly nonequilibrium (bifurcation) processes. The first condition does not operate in Mach systems." Could you please explain why you say that the first condition (i.e., effect may not precede cause) does not operate in Mach systems?

I looked at the paper which you attached to your post, and also at the essay which you submitted for last year's FQXi competition. Due probably to my own lack of technical expertise (I'm not a professional physicist), I cannot claim to understand the technical details of your papers. But I also unfortunately do not understand the broad goals of your papers. Could you please be so kind as to explain the goals of your papers in some relatively concise non-technical terms? That would be helpful. Thank you.

Cheers

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Hello Mr Smith

'The Collider, the Particle and a Theory About Fate,'

I can't believe that paper is still getting a run in the media! I don't think it is worth commenting on any more than the pounding it has already deservedly received in the "blogosphere". Any paper that includes "luck" as a testing principle surely cannot be science!!

On a more constructive note, I have just finished reading Arjen Dijksman's essay which I notice you have also read and posted a comment on. It is an excellent proposal with direct connections to the work of Durr, Goldstein et al in extending Bohm's ideas and may open the way to a more realistic interpretation of QM which can apply at all scales! I wonder if they have attempted to apply their Bohmian model to these sorts of macro experimental results? Must follow that up!

You might like to check recent comments over at Peter Lynd's discussion thread also.

Cheers for now,

Roy

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Dear Mr. Smith,

Perhaps, I was inexact.

I meant systems in which it is impossible to avoid a condition « action on distance ». Such tasks has name of the self-consistent collective field. Any particle of system is simultaneously subject to influence of all other particles of system. For example: physics of plasma or model of synthesis of polymer.

As to the broad goals.

I wished to pay attention of community that our technology works by a principle of destruction of environment. Even, if it is sparing to ecology. The decision of a problem of the self-consistent collective field can be an incitement for development of new technologies.

Yours faithfully,

Alexander Silin.

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Mr. Johnstone,

Thank you for directing my attention back to Peter Lynd's discussion thread, and also for putting in a good word there for some of the ideas we've discussed here. As you'll no doubt see, I added my two cents worth to the stew that was brewing there.

I somehow can't help wondering whether our way of thinking about time may just be too simple for many people to grasp. In discussing our ideas, people use terminology such as "the configuration of the universe *at* a particular time" (my added emphasis), but they don't seem to grasp the (perhaps too subtle?) notion that the the configuration of the universe *is* the particular time. The particular time and the particular configuration of the universe are one and the same; they're inseparable.

I've finally completed my reading of all 114 essays, and probably will now go back to re-read a good many and vote on rankings. I was reluctant to make judgements about relative rankings without first having gotten at least a general feeling for the whole spectrum. Overall, I'm well impressed by their quality. Tough competition! In this regard, I can't help wondering whether you may have given any thought to the idea of possibly submitting an essay yourself? You certainly seem well qualified to do so should the spirit move you.

Cheers

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Mr. Silin,

Thank you for your follow-up comments which clarify the points I had asked about. That is helpful. For the moment, I have no other questions. I've been kept very busy reading all the many interesting essays which have been submitted, and now probably re-reading many.

Thank you again for your reply.

Cheers

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One addendum for the record: I just noticed today that my on-line essay 'Time: Illusion and Reality,' which is reference 4 to my current FQXi essay, has recently been dealt a grievous blow in terms of its on-line appearance. Google, in its infinite wisdom, and without notifying me of its plans, did a "migration" of the essay (I'm more inclined to think of it as a death march) from its former home as a Google Page to its current home as a Google Site. In the process, the formatting and overall appearance were badly mangled, making it aesthetically most unpleasing. In fact it reminds me of one of the classic movie-style ransom notes consisting of words clipped from a newspaper and pasted together for the note.

I'm consulting with the Google Help forum seeking ways to rectify the situation, but in the meantime I'm ashamed to refer readers to view the site. The words themselves remain intact should anyone who wishes to read it in the interim be brave enough to stomach the site's overall horrid appearance. Sorry!

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To J. C. N. Smith:

While I largely agree with your position, I would like to question your ubiquitously shared opinion that predictive power is the only criterion for a theory. I rather consider science a puzzle whose element do or at least will fit together with no contradiction and no arbitrariness.

To Alexander Silin:

I cannot see any action at distance on physics of plasma.

Regards,

Eckard

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I meant "in" physics of plasma. Sorry for my typo.

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Mr Smith,

In relation to people (mis)interpreting your configuration being *at* a particular time rather than *as* a particular time, I am thinking that it may be as simple as a matter of grammar! The fact that we talk in singular terms, ie "time" and "configuration", may also connote a singular "entity"(now?) and a singular separate entity "configuration? Of course what we are really describing (without wanting to second guess you!) is an evolving *continuum* with no inherent "now" or, therefore, "future" or past".

It is interesting that Peter Lynds thought I, (and Terry Padden), were assuming that simultaneity implied the presence of "nows" and that your main principle implied the existence of an instant. Peter comes from the standpoint of a tenseless, non-discrete(except for mass/energy) reality, where time (and space?) don't exist, so that a "singular" description may be interpreted as an instant or quantum of time. Apart from the fact that I (we) think that time doesn't exist a priori, if it did, and if it was a *real* variable, then I would agree with him that quantum time would preclude motion or any state evolution because there are no "temporal interactions" to mediate change/evolution.

With the evolving configurations *as* time model, we are trying I think to re-interpret the notion of co-ordinate time in GR. So that the 4th co-ordinate and hence simultaneity, is described in terms of observer dependant positions in relative configuration/velocity space.

BTW, I support Eckard's query:-

"I cannot see any action at distance on physics of plasma."

I would say that action at a distance is more evident in, say, the formation of a complex crystal!

Cheers

Roy

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Sorry for this quick follow up, but I just had a thought rergarding the lack of "tense" or external time in objective reality, ie past, present, future. If we look at the notion of future, and think of the deadline of this essay contest for instance, all entrants were told the closing date was October 2nd, 2009. What is this really saying? It is combining a clock and calendar reading calibrated by known physical cyclic processes to describe a *particular* combined configuration of Earth's rotation angle and orbital position. Therefore if we dispose of all our clocks and calendars, we could still, with some effort, keep track of these processes and know to a good approximation when the deadline has arrived. However, if some natural catastrophe beset the solar system, completely changing Earth's rotational velocity and/or axial orientation and/or orbital motion, no one would have any way of knowing when the deadline had arrived!

Of any use?

Cheers

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Mr. Johnstone,

You wrote, "Of course what we are really describing (without wanting to second guess you!) is an evolving *continuum* with no inherent 'now' or, therefore, 'future' or 'past'."

My view is that "now" is the configuration of the universe which we observe when we look around us. This configuration is constantly evolving. The "past" is all of the configurations which preceded the one we observe with our senses. These previous configurations are no longer objectively real, but they once were objectively real. The "future" is all the configurations which will follow the one we observe with our senses. These hypothesized future configurations also are not objectively real "now," and unlike "past" configurations, they never have been objectively real. Moreover, except as intrinsically imperfect extrapolations from the configuration which we observe by looking around us, these future configurations are unknowable.

In discussing this way of looking at time as configurations of the universe it is important to remember the analogy of the elephant and the blind observers, each of whom has access to only a relatively small portion of the elephant. Their descriptions of the elephant may vary only slightly or dramatically, depending on how closely they are positioned to one another while carrying out their observations. The fact that their descriptions may vary dramatically or hardly at all, however, should not be taken as evidence that the elephant is not real or that it does not have a real configuration or that the various observers' descriptions of the elephant are not all equally valid. The universe is our elephant. Each of us sees if from a different vantage point. This is essentially the "one universe as seen by many observers rather than the many universes as seen by one mythical observer outside the universe" as advocated by Lee Smolin in 'Three Roads to Quantum Gravity (p. 48).

I agree with your comments relating all this to the contest deadline. Clocks and calendars are useful *only* insofar as they serve as a convenient shorthand for accurately referring to larger, more or less predictable, evolving configurations of the universe. I discuss this in some detail in my essay 'Time: Illusion and Reality' (to which I'm currently embarrassed to refer readers due to its horrible superficial appearance, as described in a previous post). I hope this is helpful.

Cheers

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Mr. Blumschein,

You wrote, "While I largely agree with your position, I would like to question your ubiquitously shared opinion that predictive power is the only criterion for a theory. I rather consider science a puzzle whose element do or at least will fit together with no contradiction and no arbitrariness."

I totally agree with you, and, in fact, in an earlier post I mentioned what I believe is another important test of the value of a theory, which is its explanatory power. A good theory should help us explain and understand our observations about our universe in ways which are, to borrow words from Mr. Terry Padden's essay, rational and reasonable.

Cheers

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Hallelujah! The errant website with my other essay, 'Time: Illusion and Reality,' has been put back into reasonably presentable shape, at least from the standpoint of superficial aesthetics. For better or for worse, the thoughts to be found therein remain unchanged. I still stand by them. Anyone who wishes to read it may find it here.

jcns

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Hello Mr Smith

Just a "heads up". If you are not already aware, Lee Smolin is working on a new book "The Reality Of Time"! Not sure what the ETA for publication is yet though.

Cheers

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That's fantastic news! No, I had not heard about it. I just hope Mr. Smolin has been reading all of our essays and threads so he'll have the benefit of our collective "wisdom," such as it is. Between the new Barbour and Smolin books we should have a field day sorting out all the new thinking. I know the two of them have collaborated in the past. It would be nice if their two books could somehow be complementary. Maybe asking too much? Regardless, thanks for the heads up. And if you learn any more details I'll be all eyes and ears.

Cheers

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Mr. Johnstone,

It should go without saying that I was speaking somewhat with tongue in cheek when I said in my previous post that I hope Mr. Smolin (and by extension, of course, Mr. Barbour and others) will not overlook the collective "wisdom" to be found among these FQXi essays and threads in the course of writing their new books dealing with the nature of time.

But my comment was not totally without a deep note of seriousness as well. It will be a huge disappointment to me if we continue to see books written on the nature of time by prominent, well respected physicists which do not, at a bare minimum, *discuss* the concept of time which we've been advocating here. Certainly, to some extent, Barbour's 'The End of Time' touched on our ideas, but only in a somehow frustratingly tangential way involving the disavowal of motion, a notion with which we both strongly disagree. Even if their new books were to reveal some deep, logical flaw in our concept of time it would not be totally demoralizing, so long as they could explain in a clear, rational, reasonable fashion (to again borrow Mr. Padden's words), why this way of thinking about time is not useful and/or productive. As the saying goes, time will tell.

Cheers

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Dear Roy Johnstone,

If I recall correctly, when Einstein spoke of spooky action at distance he referred to claimed propagation with superluminal velocity. In my essay I mentioned Nimtz.

Regards,

Eckard

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Dear J. C. N. Smith,

Since you dealt with the impossibility of time travel you can certainly tell me who was the first one to suggest such nonsensical possibility. I am aware of the religious belief of repetitious birth. However, as a bloody layman, I suspect that a cheeky physicist looked at the putative symmetry of laws of nature and concluded from the mathematical possibility that time travel is physically possible, too.

Who was it? Who was the first one to ascribe reality to the complete Schwartzschild solution in excess of plus infinity and minus infinity? If I recall correctly, it was not S. himself. Who was the father of such overly speculative physics? Did nobody object?

When I read Feynman's Nobel lecture, I was deeply disappointed because he revealed his utterly speculative approach instead of restriction to checkable reasoning.

Curious,

Eckard

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Mr. Blumschein,

Your question is a good one! By way of offering a simple reply please allow me to refer you to the Wikipedia write-up on time travel, which actually is quite informative as to the history of the concept, etc., and which may be found here.

The allure of the idea of time travel is certainly understandable. Who wouldn't be tempted to travel in time if it were possible? Given this natural allure of the concept, in combination with our species' penchant to indulge in wishful thinking, and voila! It's the stuff of some pleasant fantasies.

Cheers

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Mr. Johnstone,

I don't know whether you've been following the FQXi blog on the shutdown of the LHC, (to be found here). I just very belatedly read through it for the first time today and added my two cents worth to the bottom of the discussion. We really need to get on with moving this sort of talk about time travel into the same category as talk about alchemy and astrology where it belongs, once and for all.

Cheers

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Dear J. C. N. Smith,

If there was indeed something like an a priori given spacetime, then I would agree that it could be reasonable to ponder over looped worldlines. So the first father of timetravel in physics might be Einstein's teacher of mathematics Minkowski. Perhaps it was he who degraded the science of physics to science fiction including the perhaps failing search for SUSY. I am not sure but maybe you too are supporting the alternative mentioned by Zeh when he distinguished between direction of time and Minkowski's direction in time on p. 1 of introduction. Let's vote for realism, i.e., d. of t, not d. in t. .

Seriously,

Eckard

I do not amiss of you are calling me Mr.

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Hi J.C.N. Smith:

The essay that wins this contest should explain/advance the understanding with respect to sensory experience (including gravity and electromagnetism) IN GENERAL.

I will now prove that how space manifests as electromagnetic/gravitational energy is THE central and MOST valuable physical idea.

The reduction in the range and extensiveness of feeling (of the body)...

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Mr. DiMeglio,

You wrote, "The reduction in the range and extensiveness of feeling (of the body) while dreaming/sleeping is very relevant. The completion and balancing that dreams/sleep give to the unification of gravity and electromagnetism/light is consistent with the 90 degree angle of the two experiences/states (waking and dreaming)."

This quotation captures the gist of my problem with your essay, which boils down to its heavy focus and reliance on dreams and/or sleep, neither of which currently is sufficiently well understood to serve as a credible basis for a theory of physics. This is not to rule out the possibility, of course, that this situation might not change at some future time. Sorry, but that's my take on it. Good luck though.

Cheers

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Mr Smith/Eckard,

I completely agree with you both that time travel will only ever be science fiction, but perhaps Mr smith is right, that even that status gives it too much credibility!

Eckard said:-

"If there was indeed something like an a priori given spacetime, then I would agree that it could be reasonable to ponder over looped worldlines."

I am not even convinced that the GR solutions giving closed timelike loops are necessarily correct or complete. Do they fully take into account *SR* effects such as the asymmetry called "time dilation"? Strongly curved space induces extreme acceleration. Would this create the same sort of asymmetry which actually *preserves* the causality in the system worldline? So that, modelled in a Minkovsky spacetime, instead of a worldline loop phasing through the same point on the "time" axis, would we instead have a worldline *helix* oriented in the reverse direction to the original point on the time axis?

Cheers

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Dear Roy,

Thank you for supporting what I consider realism. In the thread of Vesselin Petkow I just tried to explain why I consider timespace just a mathematical tool like for instance complex impedance or evanescent mode, too. I apologize for typos.

When I blamed only Minkowski for paving the way to science fiction instead realism in physics, this was possibly not quite fair. At least he did not speak of curved space as do you. Shouldn't we rather say curved spacetime?

I consider Minkowski's famous paper a very excited one. Maybe he suddenly died from rupture of appendix for psychosomatic reasons? About at the same time, Cantor got insane, Boltzmann committed suicide, Ritz died from illness of his lung. Einstein himself was more robust but got divorced.

Regards,

Eckard

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Dear J.C.N. Smith,

Your essay was very clear and complete. You chose a topic that could be properly defined and explained within the 10 page limit, and kept it interesting. Although we don't fully understand time and how it relates to other quantities such as entropy, energy and space, I agree with your conclusions. The present is real, the past is a faded memory, and the future has not yet been written. I am not a fan of the Many Worlds interpretations that might allow disjoint interactions between these different time states. My only (admittedly nitpicking) critique is that you focused on an Ultimate Im-Possibility of Physics when I would have preferred an Ultimate Possibility of Physics. Is the glass half-full or half-empty?

Good Luck in the Contest!

Ray Munroe

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Dear Ray Munroe,

You wrote

a) the past is a faded memory,

b) the present is real,

c) the past has not yet been written.

While this is seemingly correct, I would like to ask you to clearly separate between past and present. Is a femtosecond after now still present? Or do you mean with present the timespan of your life? I argue, it is only reasonable to categorically distinguish between past and future. The now is just the borderline and has no duration at all.

The perceived fuzziness of this borderline is due to how we ascribe discrete events to a more continuous reality. For instance, the event birth is actually a process.

In reality, the distinction is necessary between either what already happened and can therefore not be changed anymore or what can be expected and influenced.

Physical theory is still tenseless. It ignores that measurement of a function of time is only possible for past data. In other words, physics suffers from an old and arrogant ideology that claimed "Man is a Machine" by La Mettrie and declares the separation mentioned by you merely an albeit obstinate illusion as still uttered by the believing physicist EA in the 50th of 20th century. The reason for such nonsense is that the laws of physics seem to be indeed independent from outer influences, so called initial conditions. The past is not simply a fading memory. Everybody of us represents special reality in that he has a family tree of his roots. The laws are the same for everybody. The same causality is obviously true for any physical process. While I try to show some consequences in my Essay 527, you might find more in M291.

Regards,

Eckard

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Dear Eckard,

The above post has a slight misquote. I said "the future has not yet been written", and you quoted me as "the past has not yet been written". The difference between the present and the future is defined by Entropy. Without a clock tick (the obvious Relativity approach), or the occurance of an event (a change in Entropy), I wouldn't know if it was now or a femtosecond later.

I fully understand the idea of an infinitesimal transformation, and integrating over a series of those infinitesimal transformations to obtain a finite transformation. It seems that such a transformation in the direction of the future could easily be confused with a "normal" passing of time (if there is anything "normal" about the nature of time), whereas such a transformation in the direction of the past would violate the Second Law of Thermodynamics.

In another essay, Hans-Thomas Elze proposes that spacetime is discrete in nature. If this is true, then our "infinitesinal" transformations become discrete quantum ones. I realize that this is where many physicists-turned-philosophers go off "the deep end" with the Many Worlds Interpretation. I have my own "crazy" ideas about multiple dimensions and String Theory. But my opinion is that Quantum Gravity is the only tenuously possible way to break strings so that we can travel in a direction contrary to what Entropy demands. Because we don't understand Quantum Gravity, we can't understand time travel, and Mr. Smith's analysis of the situation is reasonable.

I realize that FQXi had an essay contest about time last year, and many people have special interests and opinions. In another essay, Ettore Minguzzi disturbed me by proposing closed timelike curves (CTC's) and then comparing them to God. Once again, without a Theory of Quantum Gravity, we can only speculate about the possibility of CTC's.

I see you have an essay in the contest. Mine is topic #520.

Have Fun!

Ray Munroe

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Mr. Munroe,

Thank you for taking the time to read my essay and for your positive comments on it . . . both much appreciated.

Regarding the glass half full, half empty, maybe I should think about re-titling the essay . . . something along the lines of "It is Now Possible to Dismiss the Possibility of Time Travel." Just kidding!

And good luck to you in the contest, too.

Cheers

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Dear Ray Munroe,

I feel ashamed for writing past instead of future. You should be able to understand what I meant from what you wrote and from the obvious logical contradiction between a and c. Unfortunately you forgot answering at least tacitly my questions.

Do you still believe that presence has any other meaning in physics than a borderline?

Do you still not agree that the past is "living on" within their influence on any actual process? Mathematically, the influences from the past are initial conditions.

I will have a look into your essay and comment on it there or - if I consider the matter important in connection with my topic - at 527.

Regards,

Eckard

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Dear Eckard,

Sorry for the oversight - I get carried away sometimes...

I don't undersatnd exactly what time is. Is it a distinct or fuzzy border? If Hans-Thomas Elze is correct about the spacetime being discrete, then a fuzzy time border might be logical. If, on the other hand, spacetime is continuous down to the smallest scales, then we should be able to define distinct time borders. Presence is an even more complicated concept than time. Is my presence my influence on the Universe? Is presence a physical concept or a philosophical concept? Does my presence literally include just those atoms that comprise my body, or is there more to the human mind/ soul? Presence is relevant to Mr. Smith's paper in the former case, but probably not in the latter case. I understand much of the philosophy and mathematics that physics is based upon, but don't consider myself a professional philosopher.

Certainly the past has affected (past perfect, not present tense such as "is living on") our present via initial conditions, but the exact past has been perverted from our knowledge by the entropy that separates the past from the present. I think "a faded memory" is a relevant description of the past.

My paper does not directly address time. I have a 12-dimensional model that may be related to String Theory/ M-Theory. It might have two time dimensions (the 4th dimension and the 7th dimension), but I'm not sure...

Have Fun!

Ray Munroe

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Mr. Johnstone,

Your wrote (on Oct 21), "Just a 'heads up'. If you are not already aware, Lee Smolin is working on a new book 'The Reality Of Time'! Not sure what the ETA for publication is yet though."

Having now done a wee bit of (admittedly not exhaustive) searching at seemingly likely places such as Smolin's internet home page, I've yet to find any mention of this propitious new development. Any chance you could reveal the source of your news and/or a way to stay abreast of related developments?

I trust that you've seen the new article, 'Time at the Event Horizon' on the FQXi Community page. Although it touches on our topic of mutual interest I haven't come up with anything profound to add by way of comment there. Still awaiting inspiration, divine or otherwise.

Cheers

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Dear Ray Munroe,

This contest offers the chance to rethink opinions. You asked: Is (the actual moment) a distinct or fuzzy border? If you read belonging parts of my essay and the last discussions on it, you will understand my somewhat unusual position:

We may ascribe events to particular points on a scale that refers to a chosen point. The only natural reference point is the very now. So it cannot be fuzzy. It is distinct by definition, i.e., by our choice. Whether we then prefer a continuous in the sense of Peirce's definition or discrete scale for all other points of elapsed time does not matter in practice because we do anyway not have any chance to define and measure the absolutely exact distance of a second point. In this case rational numbers are sufficient.

I do not hide my reluctance to swallow the common belief in spacetime as a 4th dimension of space, and I am also not ready to share believe in further dimensions as long as there in no agreement how many dimensions correspond to reality.

When G. Cantor found out that a cube has not more points as compared with the line he reiterated the likewise ridiculous conclusion by Albert von Sachsen (1318-1390). Actually it is nonsense to ascribe a number of points to something with more than zero dimensions. Even a 3D structure that consists of a finite number of points is zero-dimensional.

I appreciate that you wrote "my presence". Accordingly I do not see it a complicated concept and something intangible and therefore inapt for physics. It always refers to an object under consideration, and it must not play any role as a state: |sign(x)|=1 for all x without exception for real numbers. In order to avoid theoretical problems we need real numbers here.

Regards,

Eckard

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Dear Eckard,

You make some interesting points. I haven't read your paper yet. I intend to read it and comment by Tuesday, 11-3.

Thank You for your time.

Ray

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Mr Smith

The source of my news about Lee Smolin's book is the blog site of Sabine Hossenfelder, one of this years essay entrants. Her blog is called "Backreaction" and the entry was from October 19 when she was reporting on procedings at the "Q2C" conference being held at the Perimiter Institute. She was, until recently, a colleague of Smolin's at Perimiter. The news was apparently revealed by director of the Institute Neil Turok and I was surprised also that there is nothing about it on Smolin's own web pages, so I get the impression that maybe the book is still in the early stages.

Her blog address is "Backreaction.blogspot.com" and I hope you have better luck than I did getting the video clips to run!

Cheers

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Mr. Johnstone,

Thank you for the lead to the info on the new Smolin book. Checked it out this evening, and was able to get the video. Took a minute to load, however, so that could be a factor if you have a less than speedy connection. Due to the fact that I'm currently away on travels and dependent on a small laptop with less than ideal audio, however, will wait until I can plug in external speakers to view the entire interview.

Again, many thanks for the good info.

Cheers

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Mr. Johnstone, et al.,

Pondering the broad theme of this year's essay competition (what's ultimately possible in physics) has led me to ask myself a couple of hypothetical questions which I'd like to toss out for general consideration and comment should anyone care to do so.

If (as seems theoretically possible, at least for the sake of a thought experiment) evolution had not equipped us with our sense of sight (but had endowed us with all of our other senses), how would our science be different? For example, would we know that information can be transmitted faster than the speed of sound? If so, how would we know? And would we have any way of discerning the fact that evolution could have equipped us with another sense beyond the four we possessed?

With apologies for waxing philosophical, good luck to all as the competition winds down to its final days.

Cheers

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Your essay is very well written in that it clearly explains your ideas. The point that you make about a particular configuration of matter in space being what we consider a particular moment in time is very important to science, in my opinion.I have also accepted this idea and consider it much more sensible than the idea of matter replicated through time or a multiverse. I like your use of the term "Configuration".

As you are aware I would go further and dispute also the reality of a singular present. Each object having its own "experience" of time rather than all objects existing within the same experienced present moment. However I do not wish to argue the point here as we have already had some discussion on another thread.

I think that whatever the outcome of the competition you have helped a few more people see another way of looking at things and perhaps it will enable more people to rid themselves of belief in fantasy time realms, time travel and belief in the grandfather paradox nonsense.I am not sure the essay demonstrates what is ultimately possible in physics but it is a good starting point and so very worthwhile.I enjoyed reading it. Good luck.

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Ms. Parry,

Thank you very much for your kind words and for your positive appraisal of my essay. Your favorable verdict means a great deal to me, because I'm well aware that you are no stranger to the topic.

I've seen reports that both Julian Barbour and Lee Smolin are writing new books on the nature of time. It's my fervent hope that one or both of these books will reflect, in at least some fashion, some of the thinking presented here. (If not, then what's the point of FQXi?)

Regarding your point of each object having its own "experience" of time, I think we do not have a disagreement about this. It's basically the Smolin/Markopoulou "one universe with many observers rather than many universes with one mythical observer" concept, at least as I see it. This is perfectly reasonable and consistent with my thinking.

On one final note, I know we're all up to our ears in reading these days, but if you ever have any time to spare, please do take a look at reference 4 to my FQXi, essay. It covers some of the same thinking, but comes at it from a slightly different direction and reaches some conclusions that are not addressed at all in the FQXi essay. If you liked the FQXi essay, you'd probably enjoy it as well.

Cheers

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"I am not sure the essay demonstrates what is ultimately possible in physics . . . ."

Just by way of clarification on this point (inasmuch as this isn't the first time this criticism has arisen), the essay competition evaluation criteria include the following:

"What role do 'impossibility' principles or other limits (e.g., sub-lightspeed signaling, Heisenberg uncertainty, cosmic censorship, the second law of thermodynamics, the holographic principle, computational limits, etc.) play in foundational physics and cosmology?"

Given this official judging criterion, I believe that addressing the impossibility of time travel is totally within the competition's guidelines.

Cheers

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Dear JCN Smith,

I certainly agree that this essay falls within the guidelines of the contest. My personal preference was for Possibilities rather than Im-Possibilities, but your topic was well-presented.

Have Fun!

Ray Munroe

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Dear JCN,

Bravo! Great Essay. "The changes we observe are the flow of time" comment is right on. I wrote an essay for the last FQXi contest that proposed that very idea. John Merryman had a similar but much shorter essay. My essay was based on a long article I wrote and published on a privately owned website in March 2008. I wrote a shorter version for FQXi and later published a similar version on my website: www.sciencewithoutfiction.com

If you are ever interested in writing something for my site in the areas of particle physics, entanglement, dark energy or the physical mechanism describing the flow of time - let me know. Keep up the good work.

Chris

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Mr. Kennedy,

Thank you for your kind, encouraging words and for your generous offer to consider a bit of my writing for your website. I'll be happy to read your essay from last year's FQXi competition and to check out your website.

If you liked this current FQXi essay, you probably also would enjoy reading reference 4 to the essay, which may be found here. In fact, you might even consider using that essay on your website? Just a thought.

Cheers

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Mr. Johnstone,

With this year's essay competition winding down, I'm reminded of a comment you made back on Aug 5th: "It would actually be good to keep the lines of communication going on this issue . . . ." I agree whole heartedly; it has been a pleasure. Judging from the fact that posts still are being added to some of the essays from last year's competition, I gather that these forums may remain open indefinitely, which seems like a good idea. Or, at a minimum, they should remain open until such time as we've resolved all the outstanding conundrums of physics once and for all. If you'd prefer to establish a correspondence outside of this forum, however, I'd be amenable to that idea as well.

Having read all 113 of the other essays in this year's competition, it would be an understatement to say that I'm curious to see which of the many interesting entries will end up among the winners. I certainly don't envy those whose task it is to make the final judgements. Regardless of the outcome, it seems indisputable that the competition has served a valuable purpose of encouraging an exchange of ideas on some worthwhile topics. And, fwiw, I'd encourage you to give serious consideration to entering an essay in any future competitions, should the topic allow. It certainly keeps things interesting.

Cheers

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JCN:

I just read your June 2008 article. It was great. I would be happy to post it on my site. However, to be fair to you - you should read my work and my $500 Challenge page before you decide, in case you don't want your work posted on a site that mainstream physicists are not too happy with. After reading your essays, I don't think you will have a problem with the theme of my work - but I won't presume anything. If you are interested, send an email to me at: ceejay1@prodigy.net and include the June 2008 article as a pdf attachment. Please also indicate in the email that you are submitting the article to be posted on www.sciencewithoutfiction.com

Take care,

Chris

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Mr Smith,

I must confess to being somewhat absent here in recent weeks due to time constraints, but it is great to see some encouraging and supportive comments to your essay from others recently! I have been doing a lot of reading lately, including many of the FQXi essays of course, and there is just so much to take in. This has all provided so much food for thought that I think I have "over-eaten"!! The various discussion threads have been most stimulating and I agree that our discussions here in your essay thread have been a pleasure to be involved in.

It would be great to continue discussions here for as long as the forum remains open, as I believe it is beneficial and important to have both input from others here and to participate in other threads to further develop all of these ideas, including yours. Early in this thread I also suggested, and made a tentative attempt at, stating some guiding principles for a model which could then perhaps be collaboratively "fleshed out". We may now be better equipped to do this, armed with some of the ideas and principles proposed by various authors and with input from some of the people who have already commented here. Once I have gathered my thoughts and completed yet more necessary reading and research I will perhaps revisit those guiding points!

I too do not envy the judges in this contest, as I believe many of the essays offer important new ways of looking at the world and new possibilities for advancing our understanding of reality and deserve recognition for stimulating areas of physics that perhaps have stagnated somewhat.

Once again, good luck to you and your "no-go theorem" for time travel with it's beautifully Machian main premise! I look forward to the judges decisions and the ongoing discussions.

Regards,

Roy J.

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Mr. Johnstone,

With the essay competition drawing to a close, it strikes me that a summation, or at least a punctuation, of our ongoing conversation up to this point may be in order.

Thomas S. Kuhn, in his marvelous book 'The Structure of Scientific Revolutions,' draws a distinction between what he terms "normal science" and "extraordinary science," or science in crisis, with the...

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Mr. Johnstone,

With the essay competition drawing to a close, it strikes me that a summation, or at least a punctuation, of our ongoing conversation up to this point may be in order.

Thomas S. Kuhn, in his marvelous book 'The Structure of Scientific Revolutions,' draws a distinction between what he terms "normal science" and "extraordinary science," or science in crisis, with the latter being caused by extraordinarily persistent and intractable anomalies which do not yield to resolution under an existing scientific paradigm. Kuhn writes, "When . . . an anomaly comes to seem more than just another puzzle of normal science, the transition to crisis and to extraordinary science has begun. The anomaly itself now comes to be more generally recognized as such by the profession. More and more attention is devoted to it by more and more of the field's most eminent men. If it still continues to resist, as it usually does not, many of them may come to view its resolution as *the* subject matter of their discipline." (pp.82-83, 3rd edition) Such persistent anomalies, according to Kuhn, are what may lead to scientific revolutions and paradigm changes.

If physics today is not already in such a state of crisis then it certainly is well on its way to being there. For evidence of this assertion one need only read Lee Smolin's 'The Trouble With Physics,' which includes his remarkable (and oft-quoted by me) comment, "More and more, I have the feeling that quantum theory and general relativity are both deeply wrong about the nature of time. It is not enough to combine them. There is a deeper problem, perhaps going back to the origin of physics." (page 256)

As I've often repeated here, I'm convinced that Smolin is correct in this assertion and that what is needed to break through the logjam in which physics now finds itself is a new paradigm for the fundamental nature of time. Moreover, I would wager that the needed paradigm will involve a Machian model such as has been proposed in my current FQXi essay and in reference 4 to this essay.

Thinking about time under the currently prevailing paradigm has become more and more obviously bankrupt. The euphemistically named "operational" definition of time, ("time is that which is measured by clocks") is then typically followed by, in essence, defining a clock as "that which measures time." To his credit, Brian Greene at least acknowledged this circularity when he wrote, "Of course, this shifts the burden to the definition of the word 'clock'; here we can somewhat loosely think of a clock as a device that undergoes perfectly regular cycles of motion. . . . Of course the meaning of 'perfectly regular cycles of motion' implicitly involves a notion of time, since 'regular' refers to equal time durations" (p. 34, 'The Elegant Universe')

This line of reasoning leads Greene to write elsewhere, "Just as we envision all of space as *really* being out there, as *really* existing, we should also envision all of time as *really* being out there, as *really* existing, too. Past , present, and future certainly appear to be distinct entities, But as Einstein once said, 'For we convinced physicists, the distinction between past, present, and future is only an illusion, however persistent.'" (p.139, 'The Fabric of the Cosmos')

Under the Machian paradigm of time which we have proposed and discussed in this thread the distinction between past, present, and future is most definitely *not* an illusion! Past, present, and future are synonymous with different configurations of our evolving universe. And I think that no serious scientist currently maintains that the universe is not an objective reality which evolves.

Given the statement by Lee Smolin quoted above, I can only conclude that he is primed to accept and embrace the need for an new paradigm for the fundamental nature of time, and I look forward eagerly to reading the new book which he supposedly is writing on the topic. If the book does not address some of the ideas we have been discussing here I will be greatly surprised, not to mention disappointed. As the saying goes, time will tell.

Cheers

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I also absolutely agree with the Smolin statement you have quoted.

I don't think Brian Greene's line of reasoning is helpful either as he seems to be just reinforcing the clock/time "circularity" by stating...

"Of course the meaning of 'perfectly regular cycles of motion' implicitly involves a notion of time, since 'regular' refers to equal time durations".

"regular" in that sense can only refer to *physical* processes. To refer to these processes in any temporal way must imply a different "rate of time" for the whole spectrum of regular processes, ie cyclic rates etc. This raises the notion of time emerging from motion in the same way as temperature, motivating some theorists to even equate time with temperature as emergent phenomena with no fundamental existence. But when viewed in this way it seems obvious that we are really talking only about physical motion/change, it is just that we "normalise" all regular process in our "operational" use (atomic clocks etc) to fit our pre-existing "time" scale.

Whilst there is no doubting the utility of our ongoing use of clocks, we must recognise that it is separate to any *fundamental* description of reality. We need a similar working paradigm to that which emerged with the establishment of Einstein's GR, where, to this day, we can and do use Newtonian mechanics "operationally" for accurately calculating orbits, rocket trajectories, escape velocities etc, with the knowledge that, apart from the constant "G" itself, the theory is fundamentally wrong! When we want to describe the "true" reality or try to develop new fundamental theories, we know we must turn to GR. Of course, we also know that GR is itself incomplete and, we think, wrong in it's representation of time, so we need to replace or at least modify it, eg. QG. Peter Lynds has shown how you can still have an evolving block Universe without the notion of time.

There seem to be some promising ideas that could perhaps fit in a Machian scheme, such as Bohmian mechanics, Dr Elliott McGucken's idea from last year of an "expanding 4th dimension", even Georgina Parry's 4d sphere "quaternion space", all of which are basically physically relational models and philosophically on the same basis as what we have discussed here. Or maybe it will be possible to approach a "TOE" by simply replacing "t" everywhere in our current theories with spatial intervals and do away with "imaginary" time and the need for "i" in other contexts?

Whatever the case, as you say, we need a large paradigm shift in the way we treat time. I too can't wait for Lee Smolin's new book!!

Cheers

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Dear J. C. N. Smith,

You quoted:

Einstein once said, 'For we convinced physicists, the distinction between past, present, and future is only an illusion, however persistent.'" (p.139, 'The Fabric of the Cosmos')

I found perhaps the same utterance in Zeh's book, 4th ed., epilog:

Four weeks before his death [in 1955, E.B.] Albert Einstein wrote in a letter of condolence to the family of his life-long friend Michael Besso (Dukas and Hoffman 1979): "Fuer uns glaeubige Physiker hat die Scheidung zwischen Vergangenheit, Gegenwart und Zukunft nur die Bedeutung einer wenn auch hartnaeckigen Illusion."

"For us believing physicists, the division into past, present and future has merely the meaning of an albeit obstinate illusion."

Zeh added that A. E. refers to 4D 'static' spacetime picture of a 'block universe'.

Later on Zeh quoted Carnap who reported that A. E. said that the problem of the Now worried him seriously. .... something that does not and cannot occur in physics ... just outside the realm of science.

I clarified elsewhere that already St. Augustinus correctly understood that there is nothing between past and future.

I hope everybody understands: Physics still suffers from belief in an a priori existing block universe. If there is no such block then one cannot travel within it. Time travel and backwards time belong to fiction. I vote for separating physics from fiction, consciousness, speculations, and mystics.

Regards,

Eckard

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Mr. Blumschein,

"Time travel and backwards time belong to fiction. I vote for separating physics from fiction, consciousness, speculations, and mystics."

Amen! Thank you for your comment. We are in total agreement on this point. I hope my essay made this point with sufficient force and clarity.

Cheers

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Mr. Johnstone,

I can only conclude from the outcome of this year's competition that I failed to make a compelling case for the impossibility of time travel. Had I done so, it is difficult to imagine that the essay would not have received some recognition.

It has been a pleasure corresponding with you. As I've mentioned in other posts, I hope you will consider submitting an essay to some future competition. You clearly are well qualified to do so.

I'll be looking forward eagerly to reading the new books on time being written by Lee Smolin and Julian Barbour.

So until later,

Cheers and Best Wishes,

jcns

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Hello again Mr Smith,

I would say your essay may have suffered from perhaps being viewed as a "negative" argument only, ie it is basically an "impossibility" theorem, albeit I believe a very important one! So it seems the judges, perhaps even more so than the community, were looking for "positive" arguments supporting only what is possible. That is my impression anyway.

As for myself submitting an essay in future, that would of course depend on the subject matter and whether I feel I have anything worthwhile to say. I think I am suffering from trying to cover too many areas in theoretical physics/cosmology as an amateur, resulting in perhaps a lack of depth of rigorous knowledge in any particular one!

I have also thoroughly enjoyed our correspondence here and the many discussions I have had with others all over the various FQXi forums. It would be good to keep this thread open for ongoing discussion, at least within the general area of your essay theme and all matters relating to the "nature of time"? I too look forward to the new Smolin and Barbour books which no doubt will be a great source of further discussion.

Speaking of Smolin, he has just published a paper which is really a response to an earlier paper by Erik Verlinde proposing that gravity is only "emergent" as an *entropic* force, rather than being fundamental!! The Verlinde paper has the physics world "buzzing" at the moment and Smolin is one of the first to jump on this idea which also relies on holographic principles based on black hole physics. It seems obvious that Smolin is wanting to make sure that the "loop quantum gravity" program is kept in the spotlight and so has hurriedly tried to show how Verlinde's idea can apply to LQG. I must say though that I had more trouble following Smolin's paper than Verlinde's. Anyway, I thought you might like to read them, Verlinde's is quite "non-technical" mostly, as the proposal seems to raise interesting question about the emergence of space and therefore "time". It is not clear to me upon first read how he can define energy (and it's conservation) in his fundamental description, when he seems to be saying that spacetime only emerges *macroscopically* from the holographic information. I would be interested to hear your thoughts on how this "entropic gravity" idea might affect our notion of time if it is right?

Below are the URL's for the two papers:-

http://arxiv.org/abs/1001.0785v1 - Verlinde

http://arxiv.org/abs/1001.3668v1 - Smolin

Once again thanks for the stimulating discussions.

Until later indeed!

Cheers

Roy J

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Mr. Johnstone,

I'm delighted to hear from you again! I somehow suspected that sooner or later you'd return to the "scene of the crime," as it were. :)

Thank you very much for the tips on the Verlinde and Smolin papers. I will indeed read them both and report back regarding any thoughts they trigger relevant to our Machian view of time and the universe. Your description of the papers is highly intriguing!

I must admit to being disappointed that my essay was not among the competition winners, as I'm sure all other authors whose essays didn't win must be. I was guardedly optimistic about my chances, despite my essay dealing with an IMpossibility rather than what's possible. I joked with one of the other essayists in the posts that perhaps I should have couched my thesis in terms of "it is now possible to disregard the possibility of time travel." But the rules of the competition clearly stated that essays dealing with impossibilities were acceptable and within the guidelines. So I return to the conclusion that my argument simply was not sufficiently convincing. Of course, it is thoroughly convincing to me, but then don't all parents think their children are all beautiful?

I'll return to the scene of the crime, too, after I've had an opportunity to read the papers you pointed out and think about them for a while. Thanks for staying in touch.

Cheers

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Mr. Johnstone,

In the hope that you've not given up on me, I offer my sincere apologies for not returning here sooner. I've been distracted by a combination of travels and health issues, but now have returned more or less to what passes here for a state of at least semi-normalcy.

Thank you again for recommending the Verlinde and Smolin papers. I've read both, and, while not pretending to comprehend all the math, I agree that they are most intriguing. It certainly seems eminently reasonable that gravity would be an emergent phenomenon, given that we've argued that time itself is emergent. I see nothing in the two papers that is in obvious conflict with our notion of time. In fact, paragraph 4.1 of the Verlinde paper includes the statement, "We want to determine the gravitational force by using virtual displacements, and calculating the associated change in energy. So, let us freeze time and keep all the matter at fixed locations." This exactly concurs with our thinking.

Given these developments, I'm even more eager than ever to see the two rumored forthcoming books on time by Smolin and Barbour. I've looked on Amazon in the hope of seeing advance release dates, but thus far to no avail. If you learn any further details about them please keep me posted, and I'll do likewise. These are exciting times in which to be contemplating these issues!

I hope this finds you in good health and spirits.

Best,

jcns

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Mr Smith

Good to hear from you. I have also had distractions due to work commitments and family issues preventing me from spending time on this "fun" stuff!

I agree that the Verlinde paper and the entropic gravity idea in general seems to fit well with our notion of time. The thermodynamic description is derived from associating a temperature to holographic screens and to points in space which generates the displacement of a particle/s. This is very good as it makes 'time"(motion) analogous to temperature as being emergent and without using quantities with dimension of time. All that is needed is temperature, spatial displacement and specification of a volume (screen) entropy. Strangely perhaps, this idea would also seem to fit well into Julian Barbour's static world where the "screens" could be thought of as static surfaces/configurations with "all the matter at fixed locations" both on the screens and in the external space. So that ironically he could be our ally here insofar as the entropic description seems to allow for the removal of time at least fundamentally and to reinterpret the 4th dimension as a sort of "spatio-energetic" dimension.

The displacement of an object requires energy and this is supplied by the entropic force acting upon it with the entropy differential. I actually think Verlinde should be describing his "equipotential" surfaces as perhaps "surfaces of equal entropy", so that he is not including a *GR* parameter in the thermodynamic description, which seems ambiguous. Anyway this seems to open the door for a "timeless" 4th dimension governing the energy transformation manifested as spatial displacement. Theories like for example Georgina Parry's "Quaternion 4D sphere" model or Elliott McGuckens' "Expanding 4th Dimension" may then come into play. These are both very much the sort of thing I am looking for.

This whole idea of a thermodynamic description for gravity actually had it's seeds in a paper by Ted Jacobson from 1995! I have just started to read it to see if i can glean some more implications for time from it, not to mention getting a better understanding of the whole entropic idea. Still not sure where Lee Smolin's recent paper sits in all of this. I had trouble following but I just can't see how loop quantum gravity can be formulated in this way. He seems to be trying to show how at least the Newton Potential can be derived from LQG but I'm not sure how that relates to Verlinde's theory.

I like the look of Verlinde's idea as it potentially facilitates more easily a timelees description, at least classically. As for the fundamental theory, well we are still left with a "problem of time" in that limlit it would seem.

Keeping my eyes peeled for any signs of the new books too.

Bye for now.

Roy J.

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Mr. Johnstone,

Thank you for your thoughts on this and for the lead to the Jacobson paper. A quick glance reveals several 1995 papers by Ted Jacobson which might be relevant to the topic. I'll plan to take a peek at them. In the unlikely case you've not seen it, additional background reading, dating from 1997, a paper by Stuart Kaufmann and Lee Smolin, may be found here. So much to read, so little time.

Regarding your comment, "I like the look of Verlinde's idea as it potentially facilitates more easily a timelees description, at least classically. As for the fundamental theory, well we are still left with a "problem of time" in that limlit it would seem." I'm not clear as to the point you mean to convey in your second sentence regarding the fundamental theory. If you find time to expand on this a bit I'd appreciate it. Thanks.

Cheers,

jcns

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Mr Smith,

Yes, that last paragraph was admittedly a bit vague. What I meant was that in the entropic gravity context, time can be clearly shown to emerge at the classical level along with gravity/spacetime. From there it is easy to apply our definition and identify time with the evolution of configurations, like temperature is identified with motion.

However, entropic gravity at present at least, says nothing about a fundamental theory, so it cannot be used to derive an alternative for the time operator in the current formalisms of quantum physics.

The "problem of time" in the form as addressed by Smolin/Kauffman et al is that if time vanishes in a quantum description of the Universe as per the Wheeler-DeWitt equation, then it should also vanish everywhere else including microscopic systems. (I think that is the thrust of the paper you referred to?). Whilst I don't think this is necessarily true, even if it were, Verlinde's idea does not give us the means to achieve it.

You and I might say (as we believe!) that our definition of time should apply equally at all scales. But the entropic gravity theory does not help us do this. If someone could propose an experiment to test whether the thermodynamic description still holds at the quantum level where we know GR does not, it might provide, not only a proof of Verlinde's thoery, but also a clue as to how to identify time with configurations at that scale in the same way.

I hope this helps clarify that final comment in my last post? The statement was very much contextual.

Cheers

Roy

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Mr. Johnstone,

Yes, thanks for your reply; that does help me understand your thinking. Much food for further thought here. How does one talk about a "configuration of the universe" at the quantum level where the uncertainty principle reigns?

I've generally thought about the notion of "time," per se, as being a purely human construct devised very early in human history to help us communicate information about macroscopic configurations of the universe in practical terms and for practical purposes of survival and commercial value. When we devised our time terminology (which, I believe, probably happened gradually and haphazardly over an extended early period in human history) nobody could possibly have anticipated the ways in which it would eventually be used (and perhaps misused) in modern mathematics and physics. It almost certainly began as a convenient but imprecise linguistics device. I suspect we are now asking it to carry far more weight than it was originally designed for or intended to handle.

Just some rambling thoughts. Thanks again for staying in touch.

Cheers,

jcns

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Mr Smith,

Your "rambling" thoughts are always welcome!

In quantum cosmology models (Wheeler-DeWitt types), the quantisation is on the classical state space with the gravity part acting on the spatial metrics (GR). So it is like a classical version of the quantum wave function acting on all the geometry and matter configuration of the Universe, where the uncertainty principle doesn't apply.

Now, I don't profess to understanding the depths of the formalism but in this type of model there are certain "constraints" on the operators evolving the wave function and in the gravity part, the W-DeW equation is the operator, with a (Hamiltonian) constraint, part of which causes time to "vanish". There are further subtleties here related to the different ways quantum mechanics and quantum cosmology treat the Hamiltonian equation (and therefore the Schrodinger equation) and their different interpretations of the wave function.

All a bit sketchy, but I hope it gives at least a bit of a "feel" for how we can talk of configurations of the Universe in a quantum mechanical way?.

This was also one of Julian Barbour's "jumping off points" motivating his argument for the absence of time!

Cheers

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Mr. Johnstone,

Many thanks for your very insightful and helpful comments. It is clear that your understanding of these subtleties is far better than mine, and your clarifications are most appreciated. As I've mentioned before, I hope you will find an opportunity to flesh out your thoughts on this topic in the form of an essay, either for FQXi or for some other forum. If/when you do, I hope you'll alert me to the fact and point me toward a copy. You have much of value to add to this ongoing conversation. I'll definitely be revisiting this thread from time to time in the future, and especially if/when we finally have the much anticipated Barbour and Smolin books in hand. In the meantime, let's continue pursuing our goal of better understanding how the universe works. As Einstein has been quoted as saying, "the most incomprehensible thing about the universe is its comprehensibility." Let's hope he was correct.

Cheers,

jcns

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Mr. Johnstone,

The plot thickens! Exciting times! You've probably seen this already but just in case not an interesting item may be found here.

Cheers!

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Mr. Johnstone,

More excitement in our mutual field of interest! I trust that you've seen the recent FQXi request for proposals for research on the nature of time, which may be may be found here. Here's an excellent opportunity for anyone to put on his/her thinking cap and put fingers to keyboards. I fear that pretty much everything I have to say on the topic of time has already been said in my on-line essay here. Strangely enough, that essay does seem to address the topics mentioned in the request for proposal rather well, imo. Any chance that you might throw your hat into this ring?

On a related topic, I've begun reading Vlatko Vedral's 'Decoding Reality: The Universe as Quantum Information,' and highly recommend it for your perusal.

Incidentally, should you ever care to contact me off-line from this thread you can reach me via email at jsjunkmail@cox.net which is an address I hardly ever check, but I will check it from time to time on the off chance that I may hear from you there. I've enjoyed our correspondence here, but am concerned lest this link somehow evaporate like morning dew when we're not looking.

Cheers

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Mr Smith,

Thanks for directing me to Vlatko Vedral's article and book. The article certainly does raise some interesting points. I must say I am also a little concerned with the lack of observational evidence for the Unruh effect upon which this entropic gravity idea seems to rely fairly heavily along with some unresolved issues around the *general* applicability of holographic principles from black hole physics. I do hope Jacobson/Verlinde are right though! It would make things like unification much easier and presumably remove the need for quantum gravity, something that is proving extremely difficult for the best minds to construct!

The FQXi 2010 research grant program will certainly be exciting to watch and see the resulting ideas and work done. From our point of view the main theme is of course perfect! Unfortunately I would not qualify for acceptance on at least two counts, firstly I work full time (unrelated to physics) and could not fit in even the part time hours requirement and secondly I am not affiliated with an institution.

Good idea to exchange alternative email addresses just in case, so here is one you can use to reach me most of the time - rjohnstone@bayside.vic.gov.au.

Cheers

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Mr. Johnstone,

Just a very quick note regarding your second reason for not participating in the FQXi 2010 research grant program; I'm reasonably confident that they'd allow you to write "independent" in the space where they ask for the name of the institution with which you're affiliated. Julian Barbour, for example, is not affiliated with an institution and lists himself as "independent."

Regarding your first and obviously most important reason, it goes without saying that only you can be the judge of that. I remain convinced, however, that you have many worthwhile things to say on this topic, and I hope the time will come when you'll be able to put them in writing.

Thank you for the alternative communication channel.

Cheers

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Oops! I hadn't seen all the blog posts about the 2010 research grant program when I wrote my previous post. It appears that they are being sticklers about requiring affiliation with a non-profit. Sorry!

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Mr. Johnstone,

In case you've not been following it, there's a rather spirited and constructive multi-logue on our favorite topic going on here. Amazingly enough, there actually appears to be some convergence of views rather than individuals merely talking past one another. I've been half-way expecting to find your footprints there, but so far have not done so. Is it possible that you, like so many of us, may be falling victim to the biggest time conundrum of all, which is known simply as not enough time?

I hope all's well.

cheers,

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Mr Smith,

I have just completed a review of the discussion you linked me to under the "Nature Of Time" grants blog and what an interesting one it is! It seems that your idea is central to the collective model being "homed in on" with only some interpretational differences of opinion. That is very gratifying.

I was particularly struck by Paul Butler's idea of a "motion amplitude" existing in a "motion continuum". This is probably the closest thing I have seen to my notion of a "velocity space" which you may recall me mentioning in early comments in this thread. The way I thought about it was probably equivalent to setting his "motion amplitude unit" as unity for the speed of light, ie C = 1. All other "amplitudes" would be relative velocities. His idea also achieves, at least partially, the removal of "time" as a dimensional component and an attempt to define an energy action principle as the 4th dimensional quantity.

I will now take more time to digest all of that thread and hopefully throw in my two cents worth.

Cheers

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Mr Smith,

Forgot to mention in that last post that, if you haven't already done so, I would recommend a look at the FQXi article "The Crystallizing Universe" about George Ellis's proposed extension to his "Evolving Block Universe" model. If you go on to read his paper, I think you will find much in it that accords with our configuration principle. The evolution is considered in terms of matter world lines rather than "time surfaces". Unfortunately, he seems to retain the notion of linear time for the matter trajectories leaving a rather ambiguous situation I think. I feel this is unnecessary considering that he also states that "past" events no longer exist and cannot be revisited and that he has now done away with his "future final block universe state". So I am wondering why he retains the "block" model at all! It is just a small step to model it the way we are, as an infinite "configuation space".

Would be interested to hear your thoughts if you have the time of course!!

Cheers

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