EPR experiments imply STR not correct?

In summary, the conversation discusses the implications of Bell's theorem and EPR-style experiments in quantum mechanics for the existence of a preferred frame. The speaker argues that these experiments demonstrate non-locality and imply an absolute simultaneity, which contradicts the idea of every frame being equivalent in Einsteinian STR. They also suggest that a theory with an absolute space, such as Lorentzian relativity, may be a more accurate explanation. The conversation also touches on the possibility of superluminal messaging and the importance of considering non-locality in the development of a local Minkowski structure for spacetime.
  • #1
zenith8
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Further to my recent post on not understanding why physical length contraction in Lorentzian relativity doesn't imply an empirical difference with Einsteinian STR:

It seems to me that Bell's theorem and the Aspect EPR-style experiments demonstrating non-locality in quantum mechanics imply an absolute simultaneity and therefore that there must be a preferred frame. The experimentally confirmed instantaneous action at a distance cannot occur otherwise (the actual results of the experiment would be observer dependent if there were no such frame).

Hence (nutter alert) Einstein is wrong, not all frames are equivalent, and therefore we must look at a theory with an absolute space (hence my interest in Lorentzian relativity). This does not seem to be controversial to me, though I have hardly ever seen it mentioned by anyone?

If you want to believe that nonlocality doesn't exist, then (it seems to me) you have only the following four options:

(1) Loopholes: claim that improving detector efficiencies in the EPR-style experiments will invalidate the results. Usually taken to be desperate clutching-at-straws.

(2) Deny `realism' i.e. the belief that there is a material world the description of which is the task of physics - but can this really be seriously questioned?

(3) Believe the many-worlds interpretation, i.e. make two problems - nonlocality and macroscopic superpositions in measurement - go away, at the cost of believing in something apparently ludicrous (eight bazillion new universes per second). NOTE TO CONFUSED: Bell's theorem refers to correlations between the results of experiments in the two (widely-separated) arms of an EPR experiment. If every damned thing that could possibly happen happens at both ends and forms a separate universe then there are no such things as correlations therefore Bell's theorem is irrelevant.

(4) Allow time travel into the past (barmy, unless one can demonstrate how or why this might happen).

None of these things seem very plausible to me.

So my question is the following. Given the fact that these experiments were done about a quarter of a century ago, and that to all intents and purposes nonlocality is an experimentally-proven fact, why has there been no wholesale switch away from Einsteinian every-frame-is-equivalent STR towards Lorentz style formulations? (note the same conclusions also apply to GTR as far as I can see).

Cheers,
Zenith
 
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  • #2
zenith8 said:
It seems to me that Bell's theorem and the Aspect EPR-style experiments demonstrating non-locality in quantum mechanics imply an absolute simultaneity and therefore that there must be a preferred frame.
Oh, it seems that way to you? Well perhaps, for the rest of us, you would propose an experiment that we could do to measure our velocity with respect to this absolute reference frame which you declare exists.
 
  • #3
cesiumfrog said:
Oh, it seems that way to you? Well perhaps, for the rest of us, you would propose an experiment that we could do to measure our velocity with respect to this absolute reference frame which you declare exists.

Look, for anyone who thinks about it for more than two seconds, the fact that experimentally-demonstrated instantaneous action at a distance implies the existence of a preferred frame is not in doubt. It shows there to be an absolute simultaneity. This has been pointed out repeatedly in the literature, I think, starting with Bell himself.

Given that Einsteinian STR denies the existence of such a frame, one could say that it has been experimentally determined to be incorrect (irrespective of whether you can determine your velocity with respect to this frame - which in fact you can't because of length contraction etc due to movement with respect to that frame in the Lorentzian relativity that we must now prefer).

Note also that superluminal signalling of this nature violates causality - that is, gives rise to backwards-in-time signals in some frames - only if one assumes a local Minkowski structure for spacetime. Historically, the Minkowski structure was developed for a local physics. If Nature turns out to be nonlocal, then one should consider revising that structure.

So your only real recourse is, as I said in the original post, is to choose one of my four reasons that nonlocality does not exist. Which do you prefer?

Although one can't measure velocity with respect to absolute space, there are interesting proposals in the QM hidden-variables literature for instantaneous signalling at a distance. Normally this is screened out by the probabilistic nature of the results i.e one can induce correlations between particles in the two wings of an EPR experiment but over repeated trials the correlations will average out.

Consider then a hidden variables interpretation such as de Broglie-Bohm pilot wave theory: here the only difference with respect to standard QM is that the wave function squared \Psi(x)^2 represents the probability that particles are at position x, rather than the probability that they are found at x in a suitable measurement. One then has the possibility of `non-equilibrium matter' where prob does not equal \Psi^2 - then all sorts of interesting things become possible, including instantaneous signalling. That would explain for example the `homogeneous universe' problem where parts of the universe always out of speed of light contact look the same - you would particularly expect to get 'non-equilibrium matter' in the early universe not long after the Big Bang.

But that's by the way. Perhaps you could explain to me why instantaneous action at a distance does not imply a preferred frame?

Cheers,
Zenith
 
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  • #4
GR does not deny the existence of an absolute reference frame (that's Occam's razor), it just isn't necessary to it (so forget about falsifying relativity so simply).

While separated measurements are correlated in QM, every specific proposal so far (and there have been many here, so I'm placing the onus on you) for superluminal messaging has been shown to correspond to mere misunderstandings of QM. (Not to mention that it is the combination of relativity into QM that corresponds with our best verified predictions.) Contrary to your assertion, no QM experiment gives any evidence that any absolute frame exists.
 
  • #5
cesiumfrog said:
GR does not deny the existence of an absolute reference frame (that's Occam's razor), it just isn't necessary to it (so forget about falsifying relativity so simply).

While separated measurements are correlated in QM, every specific proposal so far (and there have been many here, so I'm placing the onus on you) for superluminal messaging has been shown to correspond to mere misunderstandings of QM. (Not to mention that it is the combination of relativity into QM that corresponds with our best verified predictions.) Contrary to your assertion, no QM experiment gives any evidence that any absolute frame exists.


You're not getting my point. The mere existence of an infinite velocity entails the existence of an absolute simultaneity and thereby of an absolute space. Whether or not an infinite velocity can be attained in the transmission of signals is irrelevant for this argument: the one inertial system for which Einsteinian simultaneity coincides with absolute simultaneity would be the system at absolute rest - whether or not this system of absolute rest can be experimentally identified.

And as for GR, do you really think that instantaneous, non-local, spacelike, universe-wide relations of absolute simultaneity (and EPR causal correlations) are logically, mathematically and ontologically consistent with Einstein's GR? Really?

Your statement about 'it just isn't necessary' is simply an assertion of logical positivism - an idea discredited in philosophy since the 1960s - and of no relevance to the argument. It is also not true - which is what I'm trying to point out.

Anyway - though it isn't really relevant - I've told you how to transmit superluminally: find non-equilibrium matter (in the hidden-variables sense, and I'm aware this isn't easy) - and then it follows straight off (proof widely available in the literature - I could direct you to specific references if you're interested). If you're stating that's based on a misunderstanding of QM, I'd love to hear why. If you wish to contradict this, then it seems to me your only recourse is to demonstrate that e.g. hidden-variables theories along de Broglie-Bohm lines are impossible. They've been trying to do that since 1927 - and are unlikely to succeed, since the only difference between that and standard QM is in the meaning of a single word - no extra mathematics at all.

Thanks for showing an interest in this - but I haven't heard an argument from you yet that is anything other than a vague assertion of authority.

Zenith
 
  • #6
Hello zenith8

Quote:-
-----It seems to me that Bell's theorem and the Aspect EPR-style experiments demonstrating non-locality in quantum mechanics imply an absolute simultaneity and therefore that there must be a preferred frame.-----

As a beginner/layman i am puzzled by the statement about preferred frames. Before SR it was believed that light speed was infinite. You say that instantaneous action at a distance, which i assume means infinite signal velocity, leads to a preferred frame. But does this belief in infinite signal/light speed not bring us back to a pre-relativity/pre Einstein world view. This world view did not demand a preferred frame. Motion was still relative.

Perhaps you could clear up this point as i may be making incorrect assumtions as to your meaning of preferred frame.

Matheinste
 
  • #7
matheinste said:
Hello zenith8

Quote:-
-----It seems to me that Bell's theorem and the Aspect EPR-style experiments demonstrating non-locality in quantum mechanics imply an absolute simultaneity and therefore that there must be a preferred frame.-----

As a beginner/layman i am puzzled by the statement about preferred frames. Before SR it was believed that light speed was infinite. You say that instantaneous action at a distance, which i assume means infinite signal velocity, leads to a preferred frame. But does this belief in infinite signal/light speed not bring us back to a pre-relativity/pre Einstein world view. This world view did not demand a preferred frame. Motion was still relative.

Perhaps you could clear up this point as i may be making incorrect assumtions as to your meaning of preferred frame.

Matheinste
Hi Matheinste,

Sure.

Before SR it was not believed light speed was infinite as you state (the Greeks and the Arabs were talking about the finite speed of light thousands of years ago. Galileo proposed experiments to measure it using lantern shutters on different mountains, and Romer actually did measure it in I believe the 1670s - and got it more or less right.)

Newtonian space is absolute in the sense that it is distinct from the relatively moving spaces associated with inertial frames, and also because the simultaneity of two events requires only a two-place relation of simultaneous with between events 1 and 2 rather than a three place relation between event 1, event 2 and a reference frame.

Relativity already governed Newtonian mechanics i.e. it was impossible for an observer associated with an inertial frame to perform mechanical experiments which show whether he was at motion or at rest. Newton's laws of motion and gravity theory applied strictly only to the frame of absolute space or to inertial frames at rest with respect to absolute space, but they could be transformed and experssed in any sensible and apparent inertial frame (via a Galilean transformation i.e. adding velocities).

Then when electromagnetism was invented in the 1860s it was realized that it wasn't relativized in the Galilean sense. It implied that electromagnetic waves propagate through an 'ether' (conceived of as at rest with respect to absolute space) at constant speed c which was independent of the motion of the wave source. So one would think you can measure speed at which waves in ether pass your measuring apparatus i.e. you can do what you could not do in mechanics: determine the speed of your inertial frame relative to absolute space.

When Michelson-Morley failed to detect this motion (of the Earth through the ether), Fitzgerald, Lorentz and others tried to explain this result in terms of objects being physically squashed as they moved through the ether (leading to concepts of length contraction/time dilation as deduced by playing with Maxwell's equations). Mathematically this was essentially equivalent to what came later.

Roughly speaking what Einstein did (apart from stating the matter more clearly) was to take the Lorentzian relativity above and say "since you can't detect the preferred frame, we might as well say it doesn't exist" and all frames are equivalent. Hence (eventually) Minkowski spacetime. Einstein did this because of the prevailing (but now discredited) philosophy of science at the time : logical positivism (i.e. science is only about stuff you can measure). Quantum mechanics suffered greatly from this as well.

What the nonlocality experiments are pointing out is that there is a preferred frame. These are instantaneous interactions across any distance you like. If you state that something real exists (be it a particle, wave, both, or something else) which it is the object of physics to describe, then either the history as a matter of fact, or the final outcome as a matter of fact, would depend what frame an observer was in. In Minkowski spacetime, where every frame is equivalent you would get backwards in time causation. The only way out of this - as far as I can see - are the four ludicrous options I gave in my original post.

So I'm saying that nonlocality is effectively telling us to go back to the pre-Einstein Lorentzian relativity. This is normally judged to be completely empirically equivalent to Einstein but with a different ontology (things really are physically squashed, as opposed to length contraction being a perspective effect).

Hope that helps,
Zenith.
 
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  • #8
Hello zenith8

Thanks for pointing out my mistake about the belief that light speed was infinite. You understand that the point i was trying to make was that even with absolute time there is no preferred frame as motion is still relative. So i am saying not that i disbelieve that non locality/ infinite transmission speed implies a preferred frame, its just that i don't understand how it implies this. Perhaps our definitions of preferred frame differs. To me a preferred frame is one that is special or unique in nature and not just preferred in the sense of one chosen to suit our purposes or ease our calculations. I am not implying that you think that either of these are what is meant but it would help me understand your point of view if i knew what your definition of preferred frame is.

Matheinste.
 
  • #9
zenith8 said:
(1) Loopholes: claim that improving detector efficiencies in the EPR-style experiments will invalidate the results. Usually taken to be desperate clutching-at-straws.

(2) Deny `realism' i.e. the belief that there is a material world the description of which is the task of physics - but can this really be seriously questioned?

(3) Believe the many-worlds interpretation, i.e. make two problems - nonlocality and macroscopic superpositions in measurement - go away, at the cost of believing in something apparently ludicrous (eight bazillion new universes per second). NOTE TO CONFUSED: Bell's theorem refers to correlations between the results of experiments in the two (widely-separated) arms of an EPR experiment. If every damned thing that could possibly happen happens at both ends and forms a separate universe then there are no such things as correlations therefore Bell's theorem is irrelevant.

(4) Allow time travel into the past (barmy, unless one can demonstrate how or why this might happen).
1. Completely out of the question. This would be like saying that more accurate measurements might reveal that if you drop a banana, it won't fall towards the ground.

2. The implication isn't that the universe isn't realistic. It's that QM mechanics isn't. It's not inconceivable that we will someday find a better theory that is realistic. This of course requires that there's a way to exploit the loopholes in the arguments against hidden variables. See e.g. this and other articles by t'Hooft. Another possibility is that there's a way to describe exactly what the universe is like, but no way to use that description to predict the probabilities of the possible results of (a large enough range of) experiments. (E.g. if the description includes many (sub)universes, but doesn't tell us which one we live in). If that's the case, then the exact description of the universe doesn't meet the requirements of a scientific theory, and the implication is that science can't tell us what the world is really like. We might not like that, but the universe doesn't care about what we like.

3. The MWI doesn't actually say that the number of worlds is increasing. (Theories of inflation on the other hand...but that's another story). I have other issues with the MWI though. In particular, I don't think anyone can point to a well-defined set of statements that actually defines the MWI.

4. The EPR effect can't be used to send messages into the past, because there's no transfer of information from either of the measurement events to the other.

zenith8 said:
So my question is the following. Given the fact that these experiments were done about a quarter of a century ago, and that to all intents and purposes nonlocality is an experimentally-proven fact, why has there been no wholesale switch away from Einsteinian every-frame-is-equivalent STR towards Lorentz style formulations?
Because FTL signals that contain no information can't cause any paradoxes.

zenith8 said:
Look, for anyone who thinks about it for more than two seconds, the fact that experimentally-demonstrated instantaneous action at a distance implies the existence of a preferred frame is not in doubt. It shows there to be an absolute simultaneity. This has been pointed out repeatedly in the literature, I think, starting with Bell himself.
If you want to pursue this part of the discussion, you have to give an exact reference.

zenith8 said:
Note also that superluminal signalling of this nature violates causality - that is, gives rise to backwards-in-time signals in some frames - only if one assumes a local Minkowski structure for spacetime.
Wrong. FTL "signals" of this nature don't violate causality because they contain no information. (The correct statement is that an FTL signal that contains at least one bit of information violates causality unless the time required for emission/detection grows at least linearly with the distance the signal travels)

zenith8 said:
You're not getting my point. The mere existence of an infinite velocity entails the existence of an absolute simultaneity and thereby of an absolute space. Whether or not an infinite velocity can be attained in the transmission of signals is irrelevant for this argument:
Wrong. The existence of an invariant infinite velocity implies the existence of an absolute frame, but no experiments indicate that this velocity is invariant (i.e. the same in all inertial frames).
 
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  • #10
Fredrik said:
Wrong. The existence of an invariant infinite velocity implies the existence of an absolute frame, but no experiments indicate that this velocity is invariant (i.e. the same in all inertial frames).
In fact, there can only be one invariant velocity and experiments indicate that it is c. Therefore experimental results assert quite clearly that an infinite velocity is not invariant.
 
  • #11
What the nonlocality experiments are pointing out is that there is a preferred frame. These are instantaneous interactions across any distance you like.
I'm not convinced that the first sentence is correct. Since distance is irrelevant, the background could be described in any way you liked.

Your whole argument depends on the proposition that instantaneous transmission is not possible if there's no absolute frame ( preferred ) frame. Now demonstrate it logically.
 
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  • #12
matheinste said:
Hello zenith8

Thanks for pointing out my mistake about the belief that light speed was infinite. You understand that the point i was trying to make was that even with absolute time there is no preferred frame as motion is still relative. So i am saying not that i disbelieve that non locality/ infinite transmission speed implies a preferred frame, its just that i don't understand how it implies this. Perhaps our definitions of preferred frame differs. To me a preferred frame is one that is special or unique in nature and not just preferred in the sense of one chosen to suit our purposes or ease our calculations. I am not implying that you think that either of these are what is meant but it would help me understand your point of view if i knew what your definition of preferred frame is.

Matheinste.

Hi,

Sorry for the delay - I was away from the computer.

OK - let all particles in the universe be entangled i.e. the wave function of the universe cannot be factorized into products of functions which each depend only on subsets of the particle. This is not true, but that doesn't affect the argument. Then if I kick anyone particle, every other particle in the universe will respond immediately irrespective of its velocity. This is because the wave function lives in configuration space i.e. it is a function which depends on all particle positions - an abstraction which combines or binds distant particles into a single irreducible reality. It defines an absolute simultaneity.

The only inertial system for which Einsteinian simultaneity coincides with the above absolute simultaneity would be the system at absolute rest. If you continue to insist that all frames are equivalent, then you find that the history of the universe depends on the viewpoint of the observer. Hmmm.. Hence the requirement for Lorentzian relativity where such a frame does indeed exist, and you can describe the behaviour of moving frames with Lorentz transformed variables.

You say you want a 'preferred frame .. that is special or unique in nature and not just preferred in the sense of one chosen to suit our purposes or ease our calculations'. Why is the above not what you want?

Zenith
 
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  • #13
Mentz114 said:
I'm not convinced that the first sentence is correct. Since distance is irrelevant, the background could be described in any way you liked.

Your whole argument depends on the proposition that instantaneous transmission is not possible if there's no absolute frame ( preferred ) frame. Now demonstrate it logically.

See my last reply to Matheinste.

Zenith
 
  • #14
Hello zenith8

Quote:-
----You say you want a 'preferred frame is one that is special or unique in nature and not just preferred in the sense of one chosen to suit our purposes or ease our calculations'. Why is the above not what you want?----

I do not "want" anything in particular i was just asking for your definition of a preferred frame. When you start talking about the wave function of the universe its all magic to me and seems a bit over the top. I don't understand it and if i need to learn about it to follow Lorentzian relativity I'm afraid i really don't have the time. So i will drop out of the discussion none the wiser.

Matheinste
 
  • #15
matheinste said:
Hello zenith8

Quote:-
----You say you want a 'preferred frame is one that is special or unique in nature and not just preferred in the sense of one chosen to suit our purposes or ease our calculations'. Why is the above not what you want?----

I do not "want" anything in particular i was just asking for your definition of a preferred frame. When you start talking about the wave function of the universe its all magic to me and seems a bit over the top. I don't understand it and if i need to learn about it to follow Lorentzian relativity I'm afraid i really don't have the time. So i will drop out of the discussion none the wiser.

Matheinste
Hi, OK - as you wish. But my definition of a preferred frame is above, as you asked.

The wave function of the universe is a perfectly standard concept in quantum mechanics, and is neither magic nor over the top. Nothing to do with Lorentzian relativity as such.

And you don't need to talk about the wave function of the universe if you don't want to - I was just trying to make the point with a big example. Any entangled wave function of a subsystem will do.

Zenith
 
  • #16
Hello zenith8

By magic i merely meant beyond my understanding. Is it not possible to give an explanation of your definition of a preferred frame without reference to quantum theory? I believe Lorentzian relativity does predate the advent of quantum mechanics.

Matheinste
 
  • #17
The only inertial system for which Einsteinian simultaneity coincides with the above absolute simultaneity would be the system at absolute rest.
By the 'the system' you mean the universe, because you started with the wave equation of the universe. In what sense can the whole universe be 'at absolute rest' ?
Surely to speak of the universe being 'at rest' or 'in motion' is ... an oxymoron * ?


* A figure of speech in which two words of opposing meanings are used together to express two contrasting qualities in one concept; A contradiction ...
 
  • #18
Mentz114 said:
By the 'the system' you mean the universe, because you started with the wave equation of the universe. In what sense can the whole universe be 'at absolute rest' ?
Surely to speak of the universe being 'at rest' or 'in motion' is ... an oxymoron * ?

* A figure of speech in which two words of opposing meanings are used together to express two contrasting qualities in one concept; A contradiction ...

Hmmm.. OK, from the beginning.

The nonlocality experiments define a universe-wide absolute simultaneity.

Absolute simultaneity defines a global absolute separation of past and future, and thus we have a cosmological basis for a universal measure of time.

This is clearly identical to the immutable, external, unobservable, unique time of Newtonian mechanics.

By defining a universal time, we have a unique foliation of spacetime, and thus a unique space and we say this is an absolute space.

To answer your specific question, we say this is an absolute space for substantival not relational reasons. Whatever is at rest in this frame obeys the unmodified Maxwell equations. In the rest frame, whatever is at rest in the absolute rest frame denoted by x,y,z in Maxwell's equations is at rest relative to absolute space.

The absolute rest space (as distinct from the many 'relative rest' positions) is where spatial and temporal coordinates measure the real (not merely apparent) spatial and temporal values. If the universe is not at rest in this frame, then so much the worse for the universe.

My main point, then, is that Bell's EPR correlations occur at the absolute time t and so it then seems to me to be difficult, in any theory, to try and admit an absolute time but adopt a relational theory of space as in Einsteinian STR..

Is this not even a small prick* in your argument?

Zenith

* a sharp pain caused by or as if by being pricked.
 
  • #19
Hello zenith.

But all you have done is take us back to an absolute space and an absolute time, with the universe at rest relatiive to itself. We've been there before. Where does that get us.

Matheinste.
 
  • #20
matheinste said:
Hello zenith.

But all you have done is take us back to an absolute space and an absolute time, with the universe at rest relatiive to itself. We've been there before. Where does that get us.

Matheinste.

Well, I've taken us back to absolute space and absolute time based on experimental evidence.

That get's us to Lorentzian relativity (which is hardly used at present) and away from Einsteinian relativity (used by everyone at present, but which states that all frames are equivalent and is therefore incorrect, according to the above viewpoint). Such a view, if correct, has many important philosophical and possible practical implications.

Like everyone else, I don't believe it can be that easy, but if not then I'm missing the flaw in the argument.

Why doesn't nonlocality introduce a preferred foliation of spacetime?

The answer must be either that nonlocality doesn't exist (but all reasons for thinking so seem not very plausible), quantum mechanics just doesn't describe reality correctly, or that the Einsteinian view of relativity is not correct.

Zenith
 
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  • #21
zenith, I find it odd that you apparently criticised MWI but nonetheless assume existence of a "wavefunction of the entire universe" (how do you propose to escape this wavefunction evolving into a superposition of eigenstates?); moreover, on what basis can you claim "there are no such things as correlations" under MWI?

zenith8 said:
And as for GR, do you really think that instantaneous, non-local, spacelike, universe-wide relations of absolute simultaneity (and EPR causal correlations) are logically, mathematically and ontologically consistent with Einstein's GR? Really?
I'm not going to go into what Albert believed in any specific year, but modern GR certainly contains exotic solutions with warp-speed travel and children siring their own grandparents.
zenith8 said:
I've told you how to transmit superluminally: find non-equilibrium matter (in the hidden-variables sense, and I'm aware this isn't easy) - and then it follows straight off (proof widely available in the literature - I could direct you to specific references if you're interested). If you're stating that's based on a misunderstanding of QM, I'd love to hear why. If you wish to contradict this, then it seems to me your only recourse is to demonstrate that e.g. hidden-variables theories along de Broglie-Bohm lines are impossible. They've been trying to do that since 1927 - and are unlikely to succeed, since the only difference between that and standard QM is in the meaning of a single word - no extra mathematics at all.
Right, so if I prepare some matter of a kind that doesn't exist, you'll use it to demonstrate the flaws in the theories of physics? And how do you reconcile all this with QFT?
zenith8 said:
Well, I've taken us back to absolute space and absolute time based on experimental evidence.
Perhaps you would demonstrate clearly how that evidence implies that conclusion?
 
  • #22
Hello zenith8.

OK so this is the starting point for Lorentzian relativity. Unlike the assumed absolute time and space of Newton we have a "proven" or if you like "logically derived" absolute time and space. what follows? Is an aether like concept involved.

Matheinste
 
  • #23
cesiumfrog said:
zenith, I find it odd that you apparently criticised MWI but nonetheless assume existence of a "wavefunction of the entire universe" (how do you propose to escape this wavefunction evolving into a superposition of eigenstates?); moreover, on what basis can you claim "there are no such things as correlations" under MWI?

Well, this isn't a QM list, but:

The wave function of the universe has got nothing to do with MWI in particular. It is just the solution to the time-dependent Schrodinger equation. Everettians like to claim it as their own but that's not really fair.

Bits of the universe can act independently if the wave function of the universe factorizes into appropriate produce functions.

`Quantum measurement' procedures are - when we have real `hidden variable' objects with measurable properties - generally not correct measurements; they are merely experiments of a certain kind designed to respect a formal analogy with classical measurements. What do such procedures actually accomplish? They indeed generate a branching of the total wave function, with branches labelled by eigenvalues of whatever linear operator you have chosen. In the plausible realist theories you can either select a particular branch by a 'realistic wave function collapse' as in GRW, or (I prefer this) by your particles randomly ending up in the support of one of the branches (de Broglie-Bohm pilot-wave theory).

What I meant by no correlations in MWI was something like:

In an EPR experiment according to MWI, anything that can happen in either arm of the apparatus actually does happen. The proof of Bell's theorem assumes only one thing happen in each arm, therefore in MWI one cannot establish if there are or are not correlations therefore Bell's theorem is irrelevant. Or am I missing something?

Right, so if I prepare some matter of a kind that doesn't exist, you'll use it to demonstrate the flaws in the theories of physics? And how do you reconcile all this with QFT?

Saying it doesn't exist is a bit harsh. Pilot-wave hidden-variables theories involve particles and waves which guide the particles (think about how that makes the two-slit experiment intelligible).. The theory does not require that the particles are distributed as the square of the wave function, and indeed it is obviously possible that they may not be. The reason it seems that way to us is that psi^2 acts as an `equilibrium distribution'; when the particles are 'stirred' by the wave function in the way implied by the Schrodinger evolution one can show they tend to *become* distributed as psi^2 if they are not already so distributed, and they will remain so under subsequent Schrodinger evolution. There are various proposals for finding non-equilibrium matter, involving black holes, the early universe, that kind of thing.

And no I won't use it to demonstrate the flaws in the theories of physics. Physics works very well in the quantum equilibrium domain we experience. Advocates of the quantum-nonequilibrium picture (Valentini, people like that) are claiming that there is new physics associated with the nonequilibrium picture (the possibility of superluminal signalling, etc..).

As for QFT - yes, these ideas have implications there. Nonlocality implies that the underlying space-time of an adequate QFT cannot be Minkowskian, since that prohibits absolute simultaneity. The spatial-temporal structure of a 3+1 Lorentz space and time needs to be the flat space and absolute time on which QED and QCD are formulated. This will be observationally equivalent to existing QED and QCD, except where Minkwoskian relativity renders the formulations inconsistent with the observational data, includes Aspect's observations, and changes required will be changes motivated by a desire to accommodate, say, Bohm's QM, not STR.

Zenith
 
  • #24
zenith8 said:
Well, I've taken us back to absolute space and absolute time based on experimental evidence.

That get's us to Lorentzian relativity (which is hardly used at present) and away from Einsteinian relativity (used by everyone at present, but which states that all frames are equivalent and is therefore incorrect, according to the above viewpoint).
zenith8, this is patently wrong. You cannot possibly make any distinction between Lorentz's relativity and Einstein's relativity based on experimental evidence. They use the exact same equations to make all of their predictions, therefore any experimental result supporting Lorentz must also support Einstein.

Personally I don't care if you like Einstein or Lorentz better. The difference is not even worth arguing about IMO. I use both: Lorentz for understanding relativistic Doppler effect, Einstein for everything else. But if you think there is any possible experiment which could provide any evidence to pick one over the other then you either don't understand the theories or the scientific method.
 
  • #25
matheinste said:
Hello zenith8.

OK so this is the starting point for Lorentzian relativity. Unlike the assumed absolute time and space of Newton we have a "proven" or if you like "logically derived" absolute time and space. what follows? Is an aether like concept involved.

Matheinste

Right. But what the Lorentzians did was to start with a mechanical 'lumineferous' ether which was essentially 'something for electromagnetic waves to wave in'. But over the years in the face of MM and other things they gradually abstracted away all of the ether's supposed mechanical properties until there was nothing left but a preferred reference frame corresponding to absolute space. If you want to call that space an 'ether' you are welcome to do so, but that probably has unhelpful connotations so I wouldn't bother.

Zenith
 
  • #26
My main point, then, is that Bell's EPR correlations occur at the absolute time t and so it then seems to me to be difficult, in any theory, to try and admit an absolute time but adopt a relational theory of space as in Einsteinian STR
No, it's easy. I find the other option more difficult. The t in GR and SR looks very like absolute time, and the zero component of the velocity 4-vector is the ratio of the local clock to the absolute clock. But the only observable is the ratio of the clock times, in which the t part cancels out. So, in a sense, t is (absolutely) irrelevant.
 
  • #27
Hello zenith8

So. As others have said SR, Lorentz, what's the difference practically.

Matheinste
 
  • #28
DaleSpam said:
zenith8, this is patently wrong. You cannot possibly make any distinction between Lorentz's relativity and Einstein's relativity based on experimental evidence. They use the exact same equations to make all of their predictions, therefore any experimental result supporting Lorentz must also support Einstein.

Personally I don't care if you like Einstein or Lorentz better. The difference is not even worth arguing about IMO. I use both: Lorentz for understanding relativistic Doppler effect, Einstein for everything else. But if you think there is any possible experiment which could provide any evidence to pick one over the other then you either don't understand the theories or the scientific method.

I'm not patently wrong at all. The experimentally verifiable facts are as follows: the space and time coordinates of events, measured in any inertial reference system, are related to the space and time coords of the same events, as measured in any other inertial reference system, by the Lorentz transformations.

The mathematics of this is indeed the same no matter what interpretation you adopt.

From these facts one may interpret STR - philosophically speaking - in three different ways:(1) the Einsteinian interpretation - classical 3+1 ontology of space *and* time. Inertial frames all equivalent.

Problems: Can be regarded as fantastical since events pop in and out of reality as we switch reference frames. Length contraction/time dilation real physical effects (not observational perspective) but unclear why objects enduring through time suffer these (reciprocal!) effects just because in relative motion.

(2) the Minkowskian interpretation (as eventually believed by Einstein!) - 3d objects don't suffer length contraction/time dilation for simple reason that 3d objects don't exist. Reality is 4-dimensional i.e. spacetime. `A ball moving in space' is actually a 4d `worldtube' with all 3d spacelike slices equally real. Length contraction/time dilation `perspective effects'.

Problems: No objective distinction between past, present and future - can't speak of objective present world in space or of `temporal becoming' (consciousness?). All 3d observers at different times equally real - nothing singles out one as more real than others.

(3) The Lorentzian interpretation: Preserves classical notions of 3+1 space and time. Single preferred frame (`ether' if you like) and absolute simultaneity. Causal explanation for length contraction/time dilation with respect to ether. Only interpretation with unified objective reality, temporal becoming, and causal explanations.

Problems: Usually stated can't detect preferred frame so what's the point of believing this? Dangerous - supporters have a tendency to get beaten up (rather like Bohmists).So my basic point is that the experimental evidence (nonlocality) now allows you to distinguish between the interpretations - without, indeed, changing any of the mathematical predictions of the theory.

You may say that is not important, but think of the equivalent situation in quantum mechanics. There *everyone* is desperate to find some experimental evidence that will distinguish between MWI, GRW, de Broglie-Bohm pilot-waves etc..

I don't understand why you say "They use the exact same equations to make all of their predictions, therefore any experimental result supporting Lorentz must also support Einstein."

Lorentz and Einstein have different ontologies - statements about what is real - and these can be experimentally distinguished if you have evidence for a preferred frame.

Zenith
 
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  • #29
Quote:-
---Length contraction/time dilation real physical effects (not observational perspective) but unclear why objects enduring through time suffer these (reciprocal!) effects just because in relative motion.----

Why is the proposed Lorentz contraction any different.

Matheinste
 
  • #30
So my basic point is that the experimental evidence (nonlocality) now allows you to distinguish between the interpretations - without, indeed, changing any of the mathematical predictions of the theory.
The existence of EPR phenomena does not require Lorentzian relativity. They can occur equally in GR and SR. So your basic point is wrong. So is most of the other stuff in your last post.
 
  • #31
matheinste said:
Quote:-
---Length contraction/time dilation real physical effects (not observational perspective) but unclear why objects enduring through time suffer these (reciprocal!) effects just because in relative motion.----

Why is the proposed Lorentz contraction any different.

Matheinste

Actual length contractions (physical squishing) occurs in both Lorentz and Einstein 3+1 relativity. In the former, this is postulated to occur because of motion with respect to the fixed ether (and actually calculated through the modified moving fields of Maxwell's equations), in the latter case it occurs due to relative motion with respect to anything else moving in a different frame..

Silly analogy for Lorentz : drive your car underwater - you feel a drag force because you are driving through water (and this drag force makes the car shorter(!) - there is a causal explanation for it).

Einstein 3+1 implies if you drive your car in space then you are physically contracted just because of relative motion to other moving things in space - i.e. there is no causal explanation for it - it is just stated to occur. Because this is clearly a bit silly (and because of the pluralistic fragmentation of reality into distinct spaces and times) most no-preferred-frameists eventually went for the Minkowskian interpretation, where the length contraction is a perspective effect in 4d spacetime.

Zenith
 
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  • #32
Mentz114 said:
The existence of EPR phenomena does not require Lorentzian relativity. They can occur equally in GR and SR. So your basic point is wrong. So is most of the other stuff in your last post.

OK - I'm interested. This is what I actually want to know - it is my original question. Tell me how EPR phenomena occur in SR.

Zenith
 
  • #33
Something odd here

From another thread

Quote:-


Length contraction in Lorentzian relativity

--------------------------------------------------------------------------------

Hi,

I'm trying to understand Lorentzian relativity (Lorentz ether theory, whatever) which is empirically equivalent to the Einsteinian STR. I have, however, a problem in comprehending length contraction.

In the Lorentz theory we have a preferred frame and length contraction is a real physical effect. It has a causal explanation in terms of motion of the body with respect to this absolute space which causes distortions in the electromagnetic field and hence in the intermolecular forces holding rods and clocks together.

Of course no experiment has ever been performed which checks length contraction directly, as there is no known way to accelerate a macroscopic object to relativistic speeds.

However, why doesn't the following imply a difference between Einsteinian STR and Lorentz?

Imagine we can build a spaceship which will travel at 0.995c. In the frame of a stationary observer, everyone agrees that the spaceship looks squished as it flies past (because of a perspective effect in Minkowski spacetime for STR, or because it actually is squished for Lorentz).

However, if I am actually on the ship then other things inside either should look squished (because they are - Lorentz) or they do not look squished (because all inertial frames are equivalent - Einstein). Now whenever I have seen this discussed one just reads that in Lorentz theory measuring rods are distorted too so I can't measure the effect. But surely if I'm going at 0.995c then things will just look distorted (spheres not being spherical etc) and I can tell the damned measuring rod is a lot shorter than it used to be (because it's now square, rather than a long rectangular metre rule).

So maybe it's because my eyes are distorted, or whatever - but isn't this dangerous? Being compressed to the thickness of a piece of cardboard can't be good for the human body surely..

What's the flaw here? All opinions gratefully received.

Cheers,
Zenith

Quick learner?

Matheinste
 
  • #34
matheinste said:
Something odd here

Quick learner?

Matheinste



:smile: Sure. I knew f*ck all about relativity this time last week.

However, given the interpretations have different ontologies regarding whether one is physically squashed or not, it is not completely impossible that one might feel/see an observational difference at relativistic speeds. I mean, it's not like anyone has ever tried it..

The interpretation of `Bell's spaceship paradox' - see Wikipedia - I believe is still somewhat controversial - that involves physical length contractions leading to stress breaking a rope strung between two spaceships.

I just like to get these things clear in my mind.

Zenith

PS: Any smartarse saying 'and you still don't' in response to my first sentence can expect a quick unpleasant death.
 
  • #35
Hello zenith8

I just found it strange that you suddenly became a confident, apparently or truly, knowledgeable espouser of Lorentzian relativity.

Please don't call me smart.

Matheinste
 

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