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FQXi BLOGS
CATEGORY: Blog
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TOPIC: Pioneer Slows, Kilogram Goes
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The late, great Carl Sagan was fond of including this line in his essays: "But I could be wrong." The idea is not merely humble, it is profound: we do not progress in our knowledge of the universe by making dogmatic assertions; we progress by guessing (Richard Feynman's word) and then testing. I *think* that nature works this way, Sagan is saying. Here's *why* I think so. And I remain open to other possibilities.
It's that "other possibilities" clause that makes Foundational questions so interesting. And exactly because they are Foundational, they don't necessarily come up where we are expecting them. Foundational insights can emerge from time to time from places where no one is looking, perhaps because we think we pretty much already understand how things go there. (Lord Kelvin famously got egg on his face by announcing that physics was over, save for one or two smallish clouds on the horizon -- in 1900.)
 | | image: Shiny Things |
There may be one such smallish cloud brewing right now in the edges of our solar system. There, two of humanity's most notable achievements -- Pioneer 10 and Pioneer 11 -- are continuing their potentially endless voyage among the stars. The problem -- as the people at the Pioneer Anomaly Project put it – is that the spacecraft aren't where they should be. And no one knows why:
"Something strange is happening in the outer reaches of our solar system. The Pioneer 10 and 11 spacecraft are not where they are supposed to be. These missions, launched in 1972 and 1973, have covered hundreds of millions of kilometers, heading toward the edge of our solar system. But something is holding them back. Each year, they fall behind in their projected travel by about 5,000 kilometers (3,000 miles).
Jet Propulsion Laboratory scientist John Anderson and his colleagues have been searching for an explanation since 1980. But as of yet, they have found nothing conclusive; no spacecraft behavior or previously unknown property of the outer solar system can explain the deceleration of the Pioneer spacecraft. Scientists are being forced to consider the unthinkable: something may be wrong with our understanding of the laws of physics."
That last line bristles with Foundational possibilities. Have we made a radical mistake in our understanding of spacetime, gravitation, or even the laws of motion, simply because from the days of Galileo until now we've never been able to toss an object far enough away to see what happens? Granted, it isn't likely -- as Executive Director and JPL alumn Louis Friedman says,
"That prospect is tantalizing, but it is more likely there isn't a "new physics" involved, and instead something is happening within physics-as-we-know-it that hasn't been properly accounted for. There are many options: The spacecraft could be falling apart in a way we didn't account for, or we incompletely understand spacecraft behavior, or there is an error in the tracking data. Or maybe they are directing us to discover some bizarre effects of physical objects -- planets or Kuiper Belt Objects or other bodies doing strange things. Or we've incorrectly predicted the effects of the interstellar wind, or we need to change a variable in the supposed constants of mass and gravitation in the solar system."
Or maybe not. From a certain perspective -- and with all deference to the people who actually build, launch, and remotely operate the things -- a hurling craft in deep space, executing no maneuvers, should be a fairly straightforward problem in mechanics. It isn't likely, but it is just conceivable that there isn't anything untoward going on way out there at all; that the problem lies not in our stars, dear Brutus, but in our science. This is a possibility on the periphery of our understanding in more ways than one.
(Full Disclosure: I happen to be an enthusiastic member of the Planetary Society myself, and would encourage anyone interested in FQX to check them out as well.)
 | | image: East Lothian Museums |
Also from the seems-small-be-might-be-huge file this month, the kilogram is disappearing.
As the AP tells it:
"The 118-year-old cylinder that is the international prototype for the metric mass, kept tightly under lock and key outside Paris, is mysteriously losing weight -- if ever so slightly.
Physicist Richard Davis of the International Bureau of Weights and Measures in Sevres, southwest of Paris, says the reference kilo appears to have lost 50 micrograms compared with the average of dozens of copies.
'The mystery is that they were all made of the same material, and many were made at the same time and kept under the same conditions, and yet the masses among them are slowly drifting apart,' he said. 'We don't really have a good hypothesis for it.'"
What on Earth is going on? 50 micrograms -- about the mass of a fingerprint, we are told -- is no artifact. Ironically, the cylinder is kept in carefully controlled conditions specifically because it is meant to define "kilogram," an unchanging reference point in our ever-fluctuating world.
Which raises the rather Twilight Zone possibility that the official kilogram *has* remained the same, while all the *other* kilograms have gained:
"Of all the world's kilograms, only the one in Sevres really counts. It is kept in a triple-locked safe at a chateau and rarely sees the light of day -- mostly for comparison with other cylinders shipped in periodically from around the world.
'It's not clear whether the original has become lighter, or the national prototypes have become heavier,' said Michael Borys, a senior researcher with Germany's national measures institute in Braunschweig. 'But by definition, only the original represents exactly a kilogram.'"
Shades of early Einstein? My clock looks all right to me -- perhaps everyone else's clock is running slow. Which yardstick is really a yard -- yours or mine? What if mass itself changes as a result of an observer's relative motion? (Or shades of Heisenberg: What if the very attempt to make, and maintain, an absolute measurement system is inherently unachievable?)
Of course, the shrinking kilogram probably isn't telling us anything about fundamental physics. It's a glitch. The Pioneer Anomaly probably isn't telling us anything about the existence of a new fundamental force, or the structure of spacetime. These are most likely pseudo-effects, little mistakes that will be cleared up by some mathematical housekeeping, and won't require any major rethinking of physical or cosmological properties.
Of course, I could be wrong.
| | this post has been edited by the author since its original submission |
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Here is a way to look at physics from another angle. What if time is a consequence of motion, rather then the basis for it?
When two atoms collide, they create an event. The physical reality of the atoms is going from one event to the next. On the other hand, an event goes from being in the future to being in the past. Another example is that the rotation of the earth relative to the position of the sun creates days. While the earth's rotation proceeds through these units of time, any particular day goes from being in the future to being in the past. The result is that there are two directions of time. To the hands of the clock, the face goes counterclockwise. Days go from dawn to dusk, as the sun moves from east to west, but it is the earth that is rotating west to east and the sunlight is moving through the time zones.
One definition of the arrow of time is that of entropy in a closed system, but a "closed system" is a unit and these processes are the aging of this unit. This relationship of the unit and the process is the basic model that Chaos/Complexity Theory has examined. What is structured and stable, rather than growing, is subject to aging and entropy and recedes into the past. Meanwhile what is chaotic is also energetic, since there needs to be a constant influx of energy to keep it from settling into whatever is the most convenient pattern. It is where the energy goes that the future lays, because the energy is the physical reality. Either it animates the order which already exists, in which case the future is a continuation of the past. Or the order is too rigid to accommodate fresh energy and the reaction is change.
Since physics thinks of time as going toward the future, one argument to explain the consequences of quantum behavior is that multiple realities are created every time there are alternative possibilities. If we thought of time as going from the future to the past, then the quantum wave of possible outcomes is the future and the present is when this potential collapses into the order that we think of as the past.
This relationship defines our thinking as well. Our minds are constantly consuming input in the form of energy which is defining information. Because it is far more and coming at speeds far faster(much at the speed of light), then we can use, our minds are like little factories, manufacturing conceptual units called thoughts. While our brain is material, these thoughts are information, so while our senses are constantly moving toward the future, consuming input, the thoughts they create are rapidly receding into the past. There is often a tradeoff between remaining current and maintaining our sense of identity, as we try to maintain the connection between the information we continue to receive and the evolved structure of our thought processes. This explains the evolution of societies and individuals, as more primitive concepts are the foundations of identity. Just as your childhood is the foundation on which your life is built, cultural icons like Jesus or Muhammad are the points of reference that are used to define society. Also the calendar would be meaningless without a starting date. Eventually though, either the structure isn't strong enough to support the entity built on it and it collapses, radiating away the energy, or it is too rigid for continued growth and there becomes a rupture between the structure and the vital processes it supported. Either way, the energy goes toward the future and the information recedes into the past.
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Very nice post, William.
The same John Anderson has recently published a summary of another set of spacecraft anomalies that haven't gotten nearly the level of attention of the Pioneer anomalies, but are in many ways much more interesting (and baffling). They occur when a spacecraft swings past Earth on a hyperbolic trajectory (during gravitational assists). For more info, see the preprint at http://arxiv.org/abs/astro-ph/0608087 .
John, I wouldn't say that "physics thinks of time as going toward the future"; CPT symmetry is fundamental; a movie of the universe played in reverse still obeys the same fundamental laws of physics (if you also flip C and P). Both the increase of entropy and our intuitive parsing of time into "past" and "future" are consequences of a low-entropy initial boundary condition on the universe, not anything asymmetric about time itself.
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Ken,
I find a consequence of this perspective is that the narrative, beginning to end construct of time is just one side of the dichotomy. Think of a factory, in that the product, the singular unit, goes from initiation to completion, while the process, the production line, is facing the other direction, consuming raw material and expelling finished product. Just as the process of time, the hands of the clock, are constantly proceeding through the units, the hours. As with the suns energy going through the series of days from past to future, the days go from being in the future to being in the past. So as these days are starting and warming up, the energy of the sun is pouring into them. Then it drains away and goes on to the next.
You are defining time in terms of a low entropy initial boundary on the universe, yet according to current theory and measurements, there is enormous amounts of "dark" energy continuing to pour into it. What if this universe is some form of singular unit. Prior to this initial boundary, it was potential, ie. existing in the future. Currently it appears to still be growing, much as a day is still warming in the morning. Theoretically it will come to an end, either fade away, or crunch back and then it is past. Presumably this energy then goes on to the next reality. So like the hands of the clock, this energy goes on to the future, while the universe, like a single day, recedes into the past.
As the atoms create the event, energy creates the information. Rather then time being a dimension, the information is lost as the energy which manifests it moves on, so to the extent it appears a dimension, it is a loop, where strands of the past are constantly being woven back into the present. This constant reviewing and regurgitating of the past alters it as it gives structure to the present.
I guess this understanding of time comes more from studying history and its relationship to present society, than from physics. While I don't set out to argue with what I don't fully understand, it just seems to me that projecting time out as a dimension has theoretical, as well as practical complications, even though it makes a useful descriptive analogy.
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Ken, "a movie of the universe played in reverse still obeys the same fundamental laws of physics (if you also flip C and P)"
Some technical issues need to be addressed here, 1:A movie is only a recording,copy, and are in essence "virtual" recording of forward moving events? Thus Relativity insists that all copies of "original" events in spacetime, lose a fraction of information, example a human memory of an actual event, cannot be replayed in the mind of observers 100%..if one can replay events in a 100% capacity, then how would one differenciate event realities?
2)"CPT symmetry is fundamental; a movie of the universe played in reverse still obeys the same fundamental laws of physics (if you also flip C and P)."..again this is not relevant to events occuring in a forward, expanding Universe?, if the Universe was in contraction mode, then the parity of left+right would be obviously different, a simple example if I may, moving "leftwards" in a contracting Universe, would be totally the opposite to moving "leftwards" in an expanding Universe.
Think about it, in a contracting Universe, turning left or right would be difficult, as you would tend to be constrained into a direct forward motion, caused be the surrounding contracting spacetime., and consequently, trying to maintain a forward motion in an expanding spacetime Universe would result in you having no option but to veer left or right, this is the bending of spactime, governed by expansion terms.
It is my belief that the pioneer anomolies are resulting from the fact, there is slightly more expanding space away from our solar system, which locally contains most of the nearest matter to the crafts.
its not that there is more PULL from our solar system, specifically our local star, Its because the is more PUSH from the "outside" of the solar system?
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John; Some of what you say makes *intuitive* sense, but my point is that our *intuition* about time is just plain wrong (assuming physics is right about CPT symmetry). Physics is telling us that time is much more symmetric than we are inclined to accept.
Paul; Maybe I should have said that one can imagine reversing the time coordinates on the universe itself, and "observing" the universe in this unusual perspective. Some people respond that it's not the same universe if it's viewed in the opposite time direction, so sometimes I retreat to the "movie" analogy, but reversing the time in ones coordinate system should be just as valid a thought-experiment as boosting into a reference frame moving at a different velocity. In both cases you're still discussing the same physical events.
As for the Pioneer anomaly, consider this: Both Pioneer 10 and Pioneer 11 experienced the same acceleration anomaly, *towards the sun*, even though they left the solar system moving in *opposite* directions! So it's almost certainly not a galactic-neighborhood effect (the odds that the sign would flip right near the sun are extremely small). Also, if one postulates a constant anomalous acceleration on everything in the solar system, one finds problems with the orbital behavior of Earth and Mars. Even in the outer solar system, such an anomaly would mess up the observed cometary distributions. It's actually quite hard to postulate new physics to explain the Pioneer anomaly that doesn't contradict some other set of observations.
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Ken,
What is the intuitive understanding of time? The story is that Edgar Allen Poe is on record as first proposing time and space as one, yet the very notion of history tends to be linear, so I'd say time as a dimension is intuitive. That there has been incredibly complex mathematics developed to support this concept isn't proof it's the most efficient explanation. Remember epi-cycles? That it does take such complexity might well be evidence against it.
You are not really addressing my point, that time as consequence of motion, rather than basis for it, does explain a physical reality that really is just energy in space.
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Maybe there is no mystery about the Pioneer Anomaly. Paul you could be absolutely correct, this looks like a case of local observation of the global expansion parameters of the universe. The local geometry of mass concentration presents gradients (gravitational and “chronic” ???) that in simple terms has the whole universe “pushing down” on Pioneer “against the wall of gravity” of the solar system.
A similar behavior was identified and predicted by a very extensive cosmology theory developed decades ago (not here to convince anyone). This generally was identified under the name of Continuum Creation and Annihilation (CCA). This hypothesis has an omnipresent repelling mechanism that causes the cosmic expansion; and among other things, such as making the universe isotropic and homogeneous,.. .
This theory is very broad in the fields that it includes; as the name implies there is a section that deals with the expansion of the universe. There are calculated values for the “creation” of continuum (or plainly volume “created” per volume present) called “chronogenesis” , or “chi” (predicted in the 70’s published in a book in 1984) that causes expansion and also does (in end result) what the Dark Energy does and possibly the Pioneer Anomaly (plus…). The equations can be rather straightforward (4pi, critical mass density, universe size “in 4-d geometry”, Newton’s constant G) but the Physics is somewhat more complicated and must be looked at in at least complete sub-sections. The significant result for the Pioneer Anomaly is that this chi (Greek letter) causes a universal acceleration, ku, that determines things like orbit corrections of planets to the minimum Hubble age and Hubble constant (Ho = 72.0 km/(Mpc- s-s)) of the observable universe.
This universal acceleration value was calculated decades ago and is
ku = 6.996 x10^(-10) m per(s-s). calculated from theory
This is an average value over the entire accessible universe.
It was good to see local evidence of this acceleration that can perhaps be attributed to the CCA cosmology, in the form of the Pioneer Anomaly, but the magnitude of the measured value of
8.7 +-1.3 x10^(-10) m per(s-s) measured from Pioneer
even though it’s almost overlapping was not expected. From the general mass distribution of our local region it was expected that a value less than ku (by at least several percent) would be present. This larger value could mean (besides all wrong) that our local patch is less than average matter density and somewhere “nearby” there is a region of great mass concentration (Dark and Visible Matter) that has less ku magnitude. We could be in a semi-empty void within a shell. (standard candle observations could show this).
Another possibility is that the size of the universe as calculated in CCA is somewhat smaller than the actual size. But this makes the universe observable age at least 10-30% smaller than the calculated age that is within 1% of the NASA WMAP inferred age. I could be wrong, but if both the above acceleration values withstand the test of time, than the discrepancy must be due to local gradient geometry.
As for the discussion of the direction of time or events; again via CCA the universe events follow the direction of change as given by the first and second time derivative of chi. Playing backwards requires not just backwards time but in CCA much energy is needed. Also associated with this, Newton’s first law is based on motion following chi gradients along “cosmic-eigen-aging of the universe (it really do es mean something in real Physics and such things as time behavior in gravitational fields).
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Nicephorus,
It is not a question of reversing the course of events, but what is time. Is it a fundamental dimension in which motion occurs? If so, then physical activity travels along it from one event to the next. On the other hand, if it is a consequence of motion, then as events are formed by this activity, they recede into the past as other events take their place. Such as the date that is tomorrow will become, with a couple rotations of the planet, yesterday. Eliminating an entire dimension does simplify the puzzle.
On a related note, I don't see that three dimensions is an adequate description of space. For all intents and purposes it seems to be nothing more then the coordinate system of the point the three lines cross. While it is as necessary to have some frame of reference to define space as it is necessary to have a starting date for a calendar, it is still an arbitrary point of reference. The fact is that any number of such points and frames can be used to define the same space.
Competing frames of reference and the systems of organization they represent are the cause of conflict. You might say Arabs and Israelis use different coordinate systems to define the same space. This is largely the basis of Chaos Theory, where the rules may be determined, but the outcome cannot be predicted because intersecting processes yield unpredictable results, even, as experiments with cellular automata have shown, where it is feedback within the same initial structure. The story of the Tower of Babel provides an very early allegory of this process at work.
While any given map of space may be three dimensional structure, the reality is infinitely dimensional, so the extent we can project is limited and all we really know are what we remember of the past and the lessons it has taught us. Some in conflict with others. (Catch 22.)
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Ken " Is it a fundamental dimension in which motion occurs? If so, then physical activity travels along it from one event to the next. On the other hand, if it is a consequence of motion, then as events are formed by this activity, they recede into the past as other events take their place."
But then again some dimensions have "holes" within them?
Electrons are not composed of 3-D structure, it is a 2-D quantity?..an example of events in spacetime, two "solid" structures, lets say two billiard balls, are heading towards each other(one from left to right, the other right to left), they collide/impact each other and the physical laws dictate they both bounce off each other in 3-Dimensional space, thier structure identity treats each ball as identical. Now imagine if one "solid" ball was composed of a structure with a different density, ie say one ball is made of a very stiff liquid, say a gel with a high viscosity. The gel/liquid like ball will encompass the solid ball, in which direction do you think the balls will travel when they collide?
Now, for the sake of simplistic insight lets treat the "gel_ball" as a 2-dimensional structured energy, and call it an Electron, and the normal billiard ball as a 3-Dimensional energy source and call it a Proton? ..the Electron does not collide with the Proton because it is NOT 3-D, it can surround the Proton because all of 3-D structures have 2-D finite "edges" .
Dirac, in his greatest wisdom, realized that if one removes the Proton from spacetime, then there is a "hole" WRT when the Proton was, this hole is a "quantum potential/well", and the lesser dimensional Electron falls/dissapears into this, the Electron, can emerge either in the future (out of the available well), or it may emerge from the past, which happens to be the SAME quantum well !
Feynman and wheeler made the statement to this effect thus: No Electron can be detected in the Present/Now, its either in the past or the future, but never, never in the Present time!
Thus the motion and action of the Electron can be viewed as a consequence of it's dimensional make-up, which allows it to instantly dissapear and reappear at any available "hole", or vacuum.
3-Dimensions is quite adequate to describe space, but you need to add certain 2-D field quantities(not-matter) to explain spacetime, as viewed of course from a 3+1 spacetime by a 3-D structured observer.
Where has all the Anti-Matter gone?..into holes within spacetime?..existing in the Past or Future?.. (anti-matter is not detected here in the present time)...is the Elecrton really the fundemental "Anti-matter" particle?..the Electron is Not A 3-Dimensional "matter" particle, its more of a 2-Dimensional field vector wave space hopping quantity, just what you would expect Anti-Matter to consist of!
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Paul,
"Feynman and Wheeler made the statement to this effect thus: No Electron can be detected in the Present/Now, it's either in the past or the future, but never, never in the Present time!"
Does that mean the detection of the electron is always just information? Either it is potential, ie. in the future, or if detected, is simply the information of that process and subject to the uncertainty principle? Consider the consequences of it being just information. It starts as the wave of potential and upon detection, collapses into and around whatever method of measurement used, becoming the object of presumed recorded reality. It is going from the future to the past.
Using time as a dimension is like dissecting an organism. It lays everything out there for you to look at and poke and examine, but for some reason, it's rather lifeless. What if there is no dimension of time and reality really is just that ethereal energy radiating and clumping in space, with history and all the intellectual structure we attach to it as little more then the tail of a comet. Is it any wonder that the more we poke at it, the more illusionary it all seems? "The more you know, the more you know you don't know."
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I realize this point about time doesn't connect with many people. Right or wrong, it is a paradigm shift for anyone educated in physics. What is a more fundamental assumption of modern physics then four dimensional spacetime. This is not just a course correction either, but a complete one eighty. Rather then dimensions being the basis of reality, they are a crude tool for prying it apart. While linearity may be more fundamental then human consciousness, it is still a construct.
Of course, just about everything is more fundamental then human consciousness. While it is the basis of our being, it is the apex of structure.
We stare into the mirror in search of our self and wonder why we only see that blank look in return.
Sorry if I'm cluttering this discussion, but you do ask for different ways of thinking.
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John,"Does that mean the detection of the electron is always just information? Either it is potential, ie. in the future, or if detected, is simply the information of that process and subject to the uncertainty principle?"
Actually, drinking a glass of water, I know ther are Electrons contained within the liquid by fact there are Atoms?..the detection of single Electrons, or the information of single Electrons is where detection persists to evade observation WRT H.U.P ? By volume I could estimate the number of Atoms within the glass of water, if I reduce the volume down to a minimum number, I could derive the Electron numbers, but when arriving at the maximum limit, ie a single atom, I could not isolate the Electron into a corner where I could confirm its location.
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Paul,
That's part of my point; What is the physical reality, versus any possible description of it.
What brought me to this site was Max Tegmark's article in NewScientist magazine, arguing that the universe is ultimately just mathematical information. I think that information and energy are two sides of the same coin and we can define the difference between them if we think of time as a consequence of motion, rather then the basis for it.
It would be interesting to see how a larger discussion of this possibility might be initiated. Given the responses I've encountered though, my hopes are not high. It not as if many people even try to think it through. They are simply highly trained minds and time as anything other than a fundamental dimension just doesn't compute.
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