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May 24, 2013

CATEGORY: FQXi Essay Contest - Spring, 2012 [back]
TOPIC: The Assumption of a Perfectly Measurable Space-Time, the Measurement Problem in Quantum Mechanics and the Nature of Physical Laws by Rodolfo Gambini and Jorge Pullin [refresh]

Author Jorge Pullin wrote on Jul. 3, 2012 @ 11:34 GMT
Essay Abstract

The history of physics shows us that even when we have the correct physical theories at hand, it takes time to realize their most profound implications. Frequently, this is because theories that imply a new paradigm in physics are initially formulated in terms of quantities and assumptions that predate the paradigm. This obscures the true meaning of the theory in question. An example is Maxwell's electromagnetism: it is a Lorentz-invariant theory but such feature was not noticed by Maxwell, since he cast it in terms of non-invariant concepts. We argue that we face a similar situation in quantum mechanics. The theory is ordinarily formulated in terms of a classical background space and time that one assumes can be measured with infinite precision. When one takes into account that space and time have to be described as quantum entities, with fundamental limitations in their measurement, apparent conceptual problems in the quantum theory, as the measurement problem, disappear. One ends up with a quantum mechanics that is complete and does not require an external classical reality for its existence. A complete quantum theory in turn leads us to revise long held assumptions about the nature of physical laws. It naturally takes us to the position emphasized by regularist philosophers for years: physical laws derive their truth from actual relations within the world, they express only what does occur. They refer to the effects that some systems may have on others and not to what must occur in absolute, non-relational ways. Due to the probabilistic nature of the theory another assumption to be revised concerns the closure'' of physics: the laws of physics do not dictate everything that happens in the natural world. In turn this may have implications in many other philosophical issues, like for instance, the mind/body problem.

Author Bio

Jorge Pullin is the Horace Hearne Chair in Theoretical Physics at the Louisiana State University. He is the founding editor of Physical Review X, fellow of APS, AAAS, and member of the National Academy of Sciences of Argentina, Mexico and the Latin American Academy of Sciences. Rodolfo Gambini is Professor at the University of the Republic, fellow of APS, AAAS and member of the National Academy of Sciences of Argentina and the Latin American Academy of Sciences. He won the TWAS prize in physics and a member of the directory of the National Agency of Research and Innovation of Uruguay.

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Vijay wrote on Jul. 3, 2012 @ 17:30 GMT
"The Assumption of a Perfectly Measurable Space-Time" is an interesting topic.

It is interesting since it opens up question of communications as well. Measurement to what end. Why we want to communicate. With whom we want to communicate?

Do we want to communicate observation with other observer? Do we share the same language to un-ambiguously interpret (synthesis & analyse) each other's result.

In physical sciences, we attempt the same by use of standard units in communication. Thus all measurements are comparative in relation to a standard.

This is seen in Lorentz transformations (Special relativity) where standards of time and distance adopt themselves such that speed of light is measured as same. However, individually they do not measure identical between two observers. (When same object instead of similar object is used as standard.)

Fiction writers made a mountain out of paradoxical interpretation of Lorentz transformations, the fact remains that human intuition continue to follow and conform to our everyday life experiences on human scale of observations. The perception survives despite of blanks & gaps in knowledge.

Science attempts to fill these gaps in human perception. One such attempt is understanding the universe on simplistic view of ‘Space contains Energy'. Some others are based on elementary particles, field & action at a distance, and amalgamation of concepts by classification of human observations into different branches of knowledge.

The scale, granularity, quantization and quantitative expression by a mathematical number are next items on the list to understand the presumptions on measurements.

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Vijay Mohan Gupta wrote on Jul. 4, 2012 @ 13:41 GMT
"space and time have to be described as quantum entities"

Mr Jorge Pullin, I have quoted above from your text. To me an understanding of the above is important. Why they have to be described as quantum identities? What is a quantum entity? Do we have a contemporary disposition towards space and time have to be quantized?

In Pico-Physics www.picophysics.org; space and time are quantized due to presence of Knergy(Energy) in space. That is the reason, why space and time can acquire value from a continuous number range (Set of real numbers). The quantization of space and time, as a result of presence of Energy, is partial. So is that of Energy as well. It can also acquire a value from real number range. Only quantization of Knergy is primary. All other quantization phenomenon are secondary driven by natural quantization of Knergy.

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Anonymous wrote on Jul. 5, 2012 @ 12:03 GMT
There's a problem with the Montevideo interpretation. It has been noted that finite bounded closed systems undergo Poincare recurrences which lead to recoherence of "Schroedinger cats". The suggestion that quantum fluctuations of clocks prevent such recurrences is flawed, because the larger system including the quantum clock can still undergo Poincare recurrences.

Even if recoherence can be suppressed, decoherence still only leaves us with quasiclassicality. ok, FAPP, we get a mixed state. but interpretating a mixed quantum state as a classical probability distribution over pure states is still a huge leap which needs to be justified. Decoherence in no way solves the measurement problem by itself. It can only explain the emergence of quasiclassicality.

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Anonymous replied on Jul. 8, 2012 @ 19:25 GMT
Dear Anonymous,

The clock could undergo revivals only from the point of view of

an external observer endowed with an ideal clock. Otherwise the observer

will see loss of coherence and no revivals. Since no ideal clocks exist,

this issue does not really arise. What is relevant is how an object evolves

respect to other objects in the universe. Such relational evolution always

exhibits loss of coherence due to the physical limitations that clocks and

any physical system will have to keep perfectly correlated with an ideal time.

As for the second point, as explained in the essay, decoherence supplemented

by the fundamental limitations in measurement produces a true mixed state,

not only FAPP. Therefore the "huge leap" is no more. If you

want more technical details on this point please see,

Undecidability as solution to the problem of measurement: Fundamental criterion for the production of events.

Rodolfo Gambini, Luis Pedro Garcia-Pintos (Republica U., Montevideo), Jorge Pullin (Louisiana State U.). Sep 2010. 10 pp.

Published in Int.J.Mod.Phys. D20 (2011) 909-918

http://inspirehep.net/record/868882?ln=en

Best wishes

Rodolfo & Jorge

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Anonymous replied on Jul. 10, 2012 @ 09:48 GMT
The huge leap doesn't refer to getting a mixed quantum state. It refers to the reinterpretation of a mixed state obtained through some other means as a classical probability distribution over pure states. For starters, one has to deal with the "preferred basis" problem. There is no unique basis for decomposition. Zurek had shown without any coupling with an external environment --- and a closed universe has no external environment --- there can be no preferred basis.

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T H Ray replied on Jul. 11, 2012 @ 01:34 GMT
I find myself agreeing with both the anonymous correspondent, and with Rodolfo and Jorge -- I think the reconciling of the two views is in the reduction of relativity to random motion (I explain the mechanics of this counterintuitive notion in my essay, "The Perfect First Question.")

It agrees in general with Gambini-Pullin evolution.

Thoroughly enjoyable essay! -- thanks.

Tom

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Edwin Eugene Klingman wrote on Jul. 9, 2012 @ 00:25 GMT
Your 'black hole argument' [elsewhere] seems to imply the absolute impossibility of perfectly precise measurements of space-time, so a question is how to handle this measurement problem mathematically. One answer is to discretize space and time, but the Integral experiment may indicate this is unrealistic and it is certainly mathematically ugly.

One possibility is presented in my essay The Nature of the Wave Function in which a quantum condition and gravitational [weak field] condition are combined to yield a "wave function conservation" relation that assumes continuous space-time but quantized quantum states.

This provides another way to address the anonymous complaint that a 'huge leap' is necessary for interpreting a mixed quantum state as a classical probability distribution over pure states, and offers a realistic interpretation in that it does not require a reduction postulate or "collapse of the wave function".

So on a superficial level our realistic theories may have non-trivial aspects in common. I am unsure how to interpret your statement that "events occur as a result of free random choices of the systems." I don't know if this plays into your ideas of mind/body since it is unclear to me exactly who or what is "choosing".

Edwin Eugene Klingman

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Lawrence B. Crowell wrote on Jul. 10, 2012 @ 17:53 GMT
Time in relativity and quantum mechanics are completely different. The difference between them amounts to an obstruction.

Relativity defines time as an invariant. The clock on some path in spacetime counts off time in discrete equal intervals that count a proper time that measures the length of the spacetime path. For a particle in a general motion, say some wiggly path which is...

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Pentcho Valev replied on Jul. 10, 2012 @ 19:06 GMT
Lawrence B. Crowell wrote: "Time in relativity and quantum mechanics are completely different. The difference between them amounts to an obstruction."

The relativistic time is an artifact generated by the false assumption that the speed of light is independent of the speed of the light source:

http://www.amazon.com/Relativity-Its-Roots-Banesh-Hof
fmann/dp/0486406768

Relativity and Its Roots, Banesh Hoffmann: "Moreover, if light consists of particles, as Einstein had suggested in his paper submitted just thirteen weeks before this one, the second principle seems absurd: A stone thrown from a speeding train can do far more damage than one thrown from a train at rest; the speed of the particle is not independent of the motion of the object emitting it. And if we take light to consist of particles and assume that these particles obey Newton's laws, they will conform to Newtonian relativity and thus automatically account for the null result of the Michelson-Morley experiment without recourse to contracting lengths, local time, or Lorentz transformations. Yet, as we have seen, Einstein resisted the temptation to account for the null result in terms of particles of light and simple, familiar Newtonian ideas, and introduced as his second postulate something that was more or less obvious when thought of in terms of waves in an ether."

Pentcho Valev pvalev@yahoo.com

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Lawrence B. Crowell replied on Jul. 11, 2012 @ 12:35 GMT
For anyone familiar with real physics this prosaic example of throwing a projectile from a moving train is easily understood and refuted as an argument against the invariance of the speed of light. I am not sure it is worth the time and ergs of energy writing away to give that argument. BTW, there is a relativistic velocity addition formula.

LC

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Pentcho Valev replied on Jul. 11, 2012 @ 15:15 GMT
I am not sure you understand Banesh Hoffmann's text. He just suggests that, without recourse to contracting lengths etc., the Michelson-Morley experiment unequivocally confirms the assumption that the speed of light VARIES with the speed of the light source, and refutes the assumption that the speed of light is independent of the speed of the light source. See also:

http://www.pitt.edu/~jdnorton/papers/companion.doc

John Norton: "These efforts were long misled by an exaggeration of the importance of one experiment, the Michelson-Morley experiment, even though Einstein later had trouble recalling if he even knew of the experiment prior to his 1905 paper. This one experiment, in isolation, has little force. Its null result happened to be fully compatible with Newton's own emission theory of light. Located in the context of late 19th century electrodynamics when ether-based, wave theories of light predominated, however, it presented a serious problem that exercised the greatest theoretician of the day."

http://philsci-archive.pitt.edu/1743/2/Norton.pdf

John Norton: "In addition to his work as editor of the Einstein papers in finding source material, Stachel assembled the many small clues that reveal Einstein's serious consideration of an emission theory of light; and he gave us the crucial insight that Einstein regarded the Michelson-Morley experiment as evidence for the principle of relativity, whereas later writers almost universally use it as support for the light postulate of special relativity. Even today, this point needs emphasis. The Michelson-Morley experiment is fully compatible with an emission theory of light that CONTRADICTS THE LIGHT POSTULATE."

Pentcho Valev pvalev@yahoo.com

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Jason Wolfe wrote on Jul. 10, 2012 @ 19:20 GMT
Hi Lawrence,

I'm still writing my paper in which I will elaborate more on what I call Aether Medium Waves. There is a frequency spectrum from radio waves up to gamma rays. There exists a range of frequencies that exist everywhere in the universe. So I propose the existence of a medium made of aether waves that travel relative to the equation,

$c = \lambda f = \frac{1}{sqrt{\epsilon_0 \mu_0}}$

The vacuum of space is filled with cycles of EM waves across the full spectrum. Between any two points in space, there exists an infinite set of wavelengths and frequencies that equal the speed of light. I'm going for the idea that aether medium waves are a continuum of EM cycles, from very small to very large.

Every cycle has a wavelength (to measure distance) and a frequency (to measure time). A continuum of frequencies, from radio to gamma, becomes the progression of time. One atomic clock keeps time very accurately; but an infinite number of EM frequencies IS the progression of time.

Distance exists because there is an infinite set of wavelengths, from radio wave wavelengths to gamma ray wavelengths, between any two points in space.

Aether medium waves extend throughout the universe with an infinite number of cycles at each frequency.

Quantum mechanics is emergent because the fabric of space-time is made of EM wave cycles.

Does any of this make sense? Can a medium made out of EM cycles (wavelengths/periods) resolve the obstruction between QM and GR?

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Jason Wolfe replied on Jul. 10, 2012 @ 19:36 GMT
Hi Lawrence,

In other words, aether medium waves are ontological and are a real phenomena of nature. Wave functions and quantum systems are a description of aether medium waves. AM waves can be more complicated and less wave-like (e.g. clove, dumbell and sphere shapes in the case of hydrogen atom wave-functions). Strong and weak forces are built into aether waves. All particles: quarks, leptons, hadrons, mesons, every kind of particle has aether waves passing through them. Aether waves are the vacuum of space and the fabric of spacetime.

Does that help clarify AM waves?

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Lawrence B. Crowell replied on Jul. 11, 2012 @ 12:37 GMT
The quantum vacuum is filled with virtual photons. The Heisenberg uncertainty principle ΔpΔx = ħ/2 holds for the minimal electric and magnetic fields

E_0(ω) = sqrt{ħω/2Vε}, B_0(ω) = sqrt{ħVε/2ω}

with E_0(ω)B_0(ω) = ħ/2. Here ω is the frequency of the field-wave, ε is the electric permittivity of the vacuum and V is a volume used in this box normalization. E_0(ω) and B_0(ω) are the fluctuations in the electric and magnetic field at a particular frequency for that field-wave. As a result the vacuum is filled with virtual electromagnetic waves. Consequently physics today already has some of the physics you propose. However, a study of quantum mechanics and QED will reveal how to understand this properly.

Cheers LC

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Jason Wolfe replied on Jul. 11, 2012 @ 17:03 GMT
I think there is a whole new way to interpret QED and QM that nobody has ever really considered. I got the idea from the frequency of cesium which is used in atomic clocks; 9,192,631,770 Hz.

What do you call the EM frequency 9,192,631,770 Hz? Answer: a very accurate clock.

What do you call the entire EM frequency spectrum? Answer: the flow of time. I think this is the fundamental mechanism of time. Too bad I didn't have that answer for the essay contest in 2008, the nature of time. If this is so, then every phenomena of the physical universe is built upon the EM spectrum (it's a bit more complicated).

What about strong interaction and color force? Answer: I propose that an ontological object called an aether medium wave exists as a natural phenomenon. AM waves are a vast frequency spectrum; AM waves travel at c relative to their own existence as a group of frequency/wavelength pairs that always equal c. These waves must have some higher dimensional superstring characteristics that resulted in baryons, mesons, quarks and leptons at the moment of the big bang.

Molecules have chemical bonds with various energies; those energies are frequencies. Hydrogen atoms have energy levels, photons emit and absorb between energy levels. Blackbody radiation s the emission of EM radiation across a range of frequencies. I believe that quantum particles are a specific collection of frequencies and have a frequency fingerprint. If this is so, then every one of those frequencies is the particle's internal clock (clocks).

If particles really do have a frequency fingerprint, then quantum particles establish their own inertial frame as a collection of frequencies.

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Anton W.M. Biermans wrote on Jul. 30, 2012 @ 02:56 GMT
Jorge, Rodolfo,

What strikes me in all contest essays, in all physics textbooks is the (unwitting) assumption that we can imagine to look at the universe from a vantage post outside of it. We talk about the universe as if it can have certain properties as a whole, be in this or that state even though there's nothing outside of it with respect to which it can have any property, size or age.

If we assume that we live in a universe which creates itself out of nothing, without any outside intervention, then we may expect the creation of fundamental particles and the objects they form, their properties and the physical laws ruling their behavior to proceed in a trial-and-error process: what works survives, so I reject both the regularist and necessarian view.

If in a self-creating universe particles have to create themselves, each other, then particles and particle properties must be as much the product as the cause of their interactions, of fields and forces.

As I discuss in my essay (Einstein's Error), in such universe the measurement or observation interaction obviously affects the observed.

Anton

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Steve Dufourny wrote on Aug. 25, 2012 @ 10:52 GMT
Hello Mr Pullin and Mr Gambili

It is very relevant considering the mind body probelm.

you say " If they cannot distinguish between the state and a statistical mixture we say that an event has taken place."

Could you develop please. I beleive that the most important is to differenciate the bosons and the fermions and also differenciate the physical sphere and the infinite light...

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Member Benjamin F. Dribus wrote on Sep. 3, 2012 @ 23:28 GMT
Dr. Pullin and Dr. Gambini,

First, I really enjoyed your essay. I read a draft of your LQG book a couple of years ago and find your point of view enlightening. It is particularly nice to see an approach to QM with a view toward quantum gravity simultaneously shed light on the measurement problem. I do have a few questions, however.

1. Your principal point seems to be that to...

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Yuri Danoyan wrote on Sep. 6, 2012 @ 14:59 GMT
Jorge,

God's great book of Nature have been seen by Parmenides.

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Yuri Danoyan replied on Sep. 25, 2012 @ 04:10 GMT

http://fqxi.org/community/forum/topic/1413

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hoang cao hai wrote on Sep. 26, 2012 @ 02:13 GMT
Dear Rodolfo Gambini and Jorge Pullin

The two do you think: when we try to measure to determine for it,then has created the opportunity for "subatomic" was born thanks the development of technology.

That is, when more technology grows, we will find many kinds of particles smaller than "sub-atomic", but it certainly is not smaller particles "smallest and can not be divided" - (news from CERN: "identified seeds is like Higg boson, but lighter?") - if speed collisions to the "c squared" do not know "protrude" how many kinds of particles? seed would be "ultra low Higg" and will arise ....

Therefore we are "running around" the truth.

Kind Regards !

Hải.Caohoàng of THE INCORRECT ASSUMPTIONS AND A CORRECT THEORY

August 23, 2012 - 11:51 GMT on this essay contest.

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Wilhelmus de Wilde wrote on Oct. 3, 2012 @ 16:00 GMT
Dear Sirs,

There are several points that intrigued me :

1. "Revival of an event is almost impossible". fully agreed, the chance is in our causal universe one to infinite is my opinion, because we will never be in the same refernces and coordinates. However in my perception (that has no paralels with your "Montevideo Interpretation" the "event" can be "revived" by our causal consciousnes when "touching" the "alpha-probability" in Total Simultaneity , see "THE CONSCIOUSNESS CONNECTION" for more details.

2.You do not accept in fact the "collapse" of the wave function, you just accept "events" independent of an observer, if I understood your text well.

In my perception, I accept von Neumann and even go further. In my perception the events were all in the past and it is our memory that creates "reality", this reality is for every individual represented by his "Subjective Simultaneity Sphere", all these spheres together are the origin of "decohernce".

3. Events are the cause of "sensations", sensations are the essence of our reality experience, our awareness.

I hope that you can take some time to read a different perception of "reality", and await your eventual rate and or comment(s).

best regards

Wilhelmus

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Sergey G Fedosin wrote on Oct. 4, 2012 @ 09:03 GMT
If you do not understand why your rating dropped down. As I found ratings in the contest are calculated in the next way. Suppose your rating is
$R_1$
and
$N_1$
was the quantity of people which gave you ratings. Then you have
$S_1=R_1 N_1$
of points. After it anyone give you
$dS$
of points so you have
$S_2=S_1+ dS$
of points and
$N_2=N_1+1$
is the common quantity of the people which gave you ratings. At the same time you will have
$S_2=R_2 N_2$
of points. From here, if you want to be R2 > R1 there must be:
$S_2/ N_2>S_1/ N_1$
or
$(S_1+ dS) / (N_1+1) >S_1/ N_1$
or
$dS >S_1/ N_1 =R_1$
In other words if you want to increase rating of anyone you must give him more points
$dS$
then the participant`s rating
$R_1$
was at the moment you rated him. From here it is seen that in the contest are special rules for ratings. And from here there are misunderstanding of some participants what is happened with their ratings. Moreover since community ratings are hided some participants do not sure how increase ratings of others and gives them maximum 10 points. But in the case the scale from 1 to 10 of points do not work, and some essays are overestimated and some essays are drop down. In my opinion it is a bad problem with this Contest rating process. I hope the FQXI community will change the rating process.

Sergey Fedosin

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