Pilot wave theory, fundamental forces

  • #51
Here is my opinion about the books:

Duerr and Teufel - too mathematical for my taste

Bohm and Hiley - good, but slightly too philosophical for my taste

Riggs - also good, but slightly too philosophical for my taste

Holland - very physical, i.e., the best for my taste
 
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  • #52
Demystifier said:
Seems interesting.

I will talk about making Bohmian nonlocal particle mechanics compatible with relativity and particle creation/destruction. It will be based on
http://au.arxiv.org/abs/0811.1905 [Int. J. Quantum Inf. 7 (2009) 595]
http://au.arxiv.org/abs/0904.2287 [to appear in Int. J. Mod. Phys. A]
but some new insights will also be presented.

I've read the first paper before, and I liked it very much. But I still don't understand how you've managed to get around the need for a preferred frame or spacetime foliation, in your effort to construct a fundamentally Lorentz invariant deBB dynamics.
 
  • #53
Frame Dragger said:
That definitely seems like reductio ad absurdum to me...
Yes, that was the intention.

Frame Dragger said:
If I had to choose, I've shown that I'm ultimately Instrumentalist/Phenomonologist/Skeptic. It's not the most comfortable state of mind, but it works for now.
That is certainly a reasonable attitude too.
 
  • #54
Maaneli said:
I've read the first paper before, and I liked it very much. But I still don't understand how you've managed to get around the need for a preferred frame or spacetime foliation, in your effort to construct a fundamentally Lorentz invariant deBB dynamics.
Thanks for asking it. But before giving you an answer, I'll ask YOU a question. Do you see a need for any preferred foliation in Eqs. (17)-(19)?

The point is the following. Even though for each s there may exist a particular (s-dependent) Lorentz frame with respect to which the force between two particles is instantaneous, such a Lorentz frame is by no means special or ``preferred''. Instead, such a particular Lorentz frame is determined by covariant equations of motion supplemented by a particular choice of initial conditions X_a^{\mu}(0).

See also this thread:
https://www.physicsforums.com/showthread.php?t=354083
especially posts #1 and #109.

If you still have questions, I will be happy to answer them.
 
  • #55
Demystifier said:
Thanks for asking it. But before giving you an answer, I'll ask YOU a question. Do you see a need for any preferred foliation in Eqs. (17)-(19)?

The point is the following. Even though for each s there may exist a particular (s-dependent) Lorentz frame with respect to which the force between two particles is instantaneous, such a Lorentz frame is by no means special or ``preferred''. Instead, such a particular Lorentz frame is determined by covariant equations of motion supplemented by a particular choice of initial conditions X_a^{\mu}(0).

See also this thread:
https://www.physicsforums.com/showthread.php?t=354083
especially posts #1 and #109.

If you still have questions, I will be happy to answer them.

Thanks, I'll read those posts and get back to you ASAP.

Edit: I have read the posts, and reread the relevant sections of your paper, and I have comments and questions - but they will have to wait until (hopefully) tomorrow, on account of it being very late at night here in New York.
 
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  • #56
Thank you very much for the recommendations! I will buy Holland, and I will look at some of the review papers on Towler's list.
 
  • #57
SpectraCat said:
Thank you very much for the recommendations! I will buy Holland, and I will look at some of the review papers on Towler's list.
That's a good strategy IMHO. :approve:
 
  • #59
Maaneli said:
I've read the first paper before, and I liked it very much. But I still don't understand how you've managed to get around the need for a preferred frame or spacetime foliation.


it does not

http://arxiv.org/PS_cache/quant-ph/pdf/0607/0607124v1.pdf

Since the existence of a time foliation would be against the spirit of relativity, several attempts have been undertaken at obtaining a relativistic Bohm-like theory without a time foliation. I briefly describe four such proposals in this subsection, items (i)–(iv) below. However, (i)–(iii) are not satisfactory theories, and (i) and (iv) both involve some foliation-like structure, something just as much against the spirit of relativity as a time foliation.

(i) Synchronized trajectories [11, 21, 56]. Define a path s 7→ X(s) in (space-time)N as the integral curve of a vector field jψ on (space-time)N, with jψ a suitably defined current vector field obtained from a wave function ψ on (space-time)N. The path
X(s) =(X1(s), . . . ,XN(s)) defines N paths in space-time, parametrized by a joint parameter s, which are supposed to be the particle world lines. This approach is based on a naive replacement of space with space-time. Apparently, it does not possesses any equivariant measure, and thus does not predict any probabilities.
Moreover, it does introduce a foliation-like structure: The joint parametrization defines a synchronization between different world lines, as it defines which point on one world line is simultaneous to a given (spacelike separated) point on a second world line. Indeed, the synchronization is encoded in the world lines since, if N non-synchronous points X1(s1), . . . ,XN(sN) on the N world lines are chosen, then the integral curve s → Y (s) of jψ starting from Y (0) =(X1(s1), . . . ,XN(sN)) will generically lead to different world lines than X.

11.-Berndl, K., Durr, D., Goldstein, S., Zangh`ı, N.: Nonlocality, Lorentz invariance, and Bohmian quantum theory. Phys. Rev.A 53: 2062–2073(1996).
21.-Dewdney, C., Horton, G.: A Non-Local, Lorentz-Invariant, Hidden-Variable Interpretation of Relativistic Quantum Mechanics Based on Particle Trajectories. J. Phys. A: Math. Gen. 34: 9871–9878 (2001).
56.-Nikolic, H.: Relativistic Quantum Mechanics and the Bohmian Interpretation. Foundations of Physics Letters 18: 549–561 (2005).










Foliation independent:

http://arxiv.org/PS_cache/quant-ph/pdf/0607/0607124v1.pdf

The GRW theory can be made relativistic, without a time foliation or any similar structure, when using the flash ontology [72] [74].


The foliation independence of the model can be expressed in the following way: With every spacelike 3-surface epsilon in the future of epsilon 0 there is associated a wave function ψ epsilon on epsilonN , the conditional wave function, which depends on all flashes between epsilon0 and epsilon, as well as on the seed flashes before epsilon0 and, of course, on the initial wave function. (Indeed,the conditional wave function collapses at every flash.)


.-72 Tumulka, R.: A Relativistic Version of the Ghirardi–Rimini–Weber Model. To appear in J. Statist. Phys. (2006).
.-74 Tumulka, R.: Collapse and Relativity.On the Present Status of Quantum Mechanics, AIP Conference Proceedings 844, 340–352. American Institute of Physics (2006).
 
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  • #60
Maaneli

You clearly have a strong grasp of the pilot wave theory, can you explain your understanding to a waitress? I'm concerned about time in the quantum world, not gravity. Gravity in quantum terms, if you forget the standard model that will be proven accurate but hugely misinterpreted eventually, can be easily described in quantum-relavatistic terms that are equivalent to recent experiments where blobs of oil find their way around a maze. Mass creates a potential difference in the background fabric. The mechanism is beyond current theories, but it's most certainly not any Higgs particle that imparts mass to itself. Until we accept that the background fabric is more than minowski spacetime, and that our post-enlightenment view is a barrier in terms of understanding that our physics is looking at a holographic plate from the perspective of both the surface image and the projected image, we will hide under Bohr's clever arguments. We need to connect the holographic principle with non locality in QM. We need to really understand the inside out view we have of reality where relativity says that there is no such thing as time for photons and electrons.

We think of relativity as the enemy of QM. In reality, Einstein gave us a theory that was ahead of it's time.
 
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  • #61
SimonA said:
Maaneli

You clearly have a strong grasp of the pilot wave theory, can you explain your understanding to a waitress? I'm concerned about time in the quantum world, not gravity. Gravity in quantum terms, if you forget the standard model that will be proven accurate but hugely misinterpreted eventually, can be easily described in quantum-relavatistic terms that are equivalent to recent experiments where blobs of oil find their way around a maze. Mass creates a potential difference in the background fabric. The mechanism is beyond current theories, but it's most certainly not any Higgs particle that imparts mass to itself. Until we accept that the background fabric is more than minowski spacetime, and that our post-enlightenment view is a barrier in terms of understanding that our physics is looking at a holographic plate from the perspective of both the surface image and the projected image. We need to connect the holographic principle with non locality in QM. We need to really understand the inside out view we have of reality where relativity says that there is no such thing as time for photons and electrons.

We think of relativity as the enemy of QM. In reality, Einstein gave us a theory that was ahead of it's time.

All fine notions, if true, but science does not embrace the assumption first and then seek to disprove. The process may be slow, and further retarded by the near-impossiblity of testing some notions (The Holographic Principle is fascinating, but there is NOTHING to show it's true yet). There is a difference between the physics and the metaphysics, and it's just that fine line (clear and bright though it is) that has had Insturmentalism and TCI as the primary working notions in QM. They work. It's implicit in many such interpretations that the reality they describe is not a perfect or absolute description, but the work is done in the math, and for that steps must be taken in sequence. If you want breakthroughs in unifying posits, conjectures and notions... the breakthrough is going to emerge from experimental evidence or a mathematical/computing breakthrough.

Barring that, this is a field of incrementalism because it works.

EDIT: Other than the unecessary comment about female waitstaff being less than crisp, why should a coherent theory of QM or SR/GR or what supercedes them be explicable to a layperson at all? I'm fairly sure that THP is beyond the average career waiter/waitress unless you use shadow-on-landscape analogies and leave it at that.
 
  • #62
yoda jedi said:
it does not

http://arxiv.org/PS_cache/quant-ph/pdf/0607/0607124v1.pdf

Since the existence of a time foliation would be against the spirit of relativity, several attempts have been undertaken at obtaining a relativistic Bohm-like theory without a time foliation. I briefly describe four such proposals in this subsection, items (i)–(iv) below. However, (i)–(iii) are not satisfactory theories, and (i) and (iv) both involve some foliation-like structure, something just as much against the spirit of relativity as a time foliation.

(i) Synchronized trajectories [11, 21, 56]. Define a path s 7→ X(s) in (space-time)N as the integral curve of a vector field jψ on (space-time)N, with jψ a suitably defined current vector field obtained from a wave function ψ on (space-time)N. The path
X(s) =(X1(s), . . . ,XN(s)) defines N paths in space-time, parametrized by a joint parameter s, which are supposed to be the particle world lines. This approach is based on a naive replacement of space with space-time. Apparently, it does not possesses any equivariant measure, and thus does not predict any probabilities.
Moreover, it does introduce a foliation-like structure: The joint parametrization defines a synchronization between different world lines, as it defines which point on one world line is simultaneous to a given (spacelike separated) point on a second world line. Indeed, the synchronization is encoded in the world lines since, if N non-synchronous points X1(s1), . . . ,XN(sN) on the N world lines are chosen, then the integral curve s → Y (s) of jψ starting from Y (0) =(X1(s1), . . . ,XN(sN)) will generically lead to different world lines than X.

11.-Berndl, K., Durr, D., Goldstein, S., Zangh`ı, N.: Nonlocality, Lorentz invariance, and Bohmian quantum theory. Phys. Rev.A 53: 2062–2073(1996).
21.-Dewdney, C., Horton, G.: A Non-Local, Lorentz-Invariant, Hidden-Variable Interpretation of Relativistic Quantum Mechanics Based on Particle Trajectories. J. Phys. A: Math. Gen. 34: 9871–9878 (2001).
56.-Nikolic, H.: Relativistic Quantum Mechanics and the Bohmian Interpretation. Foundations of Physics Letters 18: 549–561 (2005).

Good timing, I was just about to cite this paper and this exact section, as this synchronized trajectories approach to Bohm-Dirac theory is exactly what Demystifier proposes in equations (17)-(19) in his paper.

So, Demystifier, you asked if I see the need for a preferred foliation in equations (17)-(19), and my answer would be yes, because of the reasoning given above by Tumulka.

Another problematic issue for the synchronized trajectories approach seems to be the statement that it "apparently does not possesses an equivariant measure". I'm sure Demystifier will disagree with that, so perhaps it's best to go straight to the argument given in the 1996 Berndl et. al paper, for why this is so:

-Berndl, K., Durr, D., Goldstein, S., Zangh`ı, N.: Nonlocality, Lorentz invariance, and Bohmian quantum theory. Phys. Rev.A 53: 2062–2073(1996).
http://arxiv.org/abs/quant-ph/9510027

They argue (see section 4) that the reparameterization invariant Dirac current velocity (see equation 32), is not Lorentz invariant because it is not of the form J_k/rho for more than one particle. Thus, equivariance does not hold in any obvious way for a multi-particle, multi-time Bohm-Dirac theory.

On the other hand, Demystifier seems to suggest that equivariance does hold by writing the multi-time, multi-particle Dirac wavefunction in polar form, assuming that the polar decomposition of the N-particle multi-time Dirac equation goes through, and then looking at the relativistic continuity equation for the multi-time, multi-particle Dirac four-current (which seems to imply equivariance). It is unclear to me which argument is correct, and hopefully Demystifier will address Berndl et. al's point.
 
  • #63
SimonA said:
Maaneli

You clearly have a strong grasp of the pilot wave theory, can you explain your understanding to a waitress? I'm concerned about time in the quantum world, not gravity. Gravity in quantum terms, if you forget the standard model that will be proven accurate but hugely misinterpreted eventually, can be easily described in quantum-relavatistic terms that are equivalent to recent experiments where blobs of oil find their way around a maze. Mass creates a potential difference in the background fabric. The mechanism is beyond current theories, but it's most certainly not any Higgs particle that imparts mass to itself. Until we accept that the background fabric is more than minowski spacetime, and that our post-enlightenment view is a barrier in terms of understanding that our physics is looking at a holographic plate from the perspective of both the surface image and the projected image, we will hide under Bohr's clever arguments. We need to connect the holographic principle with non locality in QM. We need to really understand the inside out view we have of reality where relativity says that there is no such thing as time for photons and electrons.

We think of relativity as the enemy of QM. In reality, Einstein gave us a theory that was ahead of it's time.

Not sure why I was singled out, but I basically agree with Frame Dragger's response to your waitress question.
 
  • #64
Yoda jedi and Maaneli,

The question of equivariant probability density is indeed the crucial question. My answer to this question is better explained in my second paper
http://xxx.lanl.gov/abs/0904.2287 [to appear in Int. J. Mod. Phys. A]
Appendix B.
The point is the following. There is no equivariance in the sense of Eq. (127). However, there IS equivariance in the sense of Eq. (125).
Berndl et al consider only the equivariance of the form of (127) [actually generalized to the case of many particles] and do not consider the equivariance of the form of (125) [which can also be generalized to the case of many particles]. Therefore, their conclusion that there is no equivariance has only a partial validity. The crucial difference between (127) and (125) is that the latter treats time and space on an equal footing (which is very relativistic in spirit), while the former does not treat time and space on an equal footing.

To conclude, my claim is that time should be treated on an equal footing with space, and that this, among other things, solves the problem of equivariance.
 
  • #65
yoda jedi said:
i
Moreover, it does introduce a foliation-like structure:
Yes, but it does not introduce a PREFERRED foliation-like structure. Instead, such a structure is determined dynamically, through the choice of initial conditions.

It is analogous to the fact that a planet also defines a particular Lorentz frames (the one with respect to which it is at rest), but it does not mean that classical laws of physics describing the motion of the planet are not relativistic covariant.
 
  • #66
Maaneli said:
On the other hand, Demystifier seems to suggest that equivariance does hold by writing the multi-time, multi-particle Dirac wavefunction in polar form, assuming that the polar decomposition of the N-particle multi-time Dirac equation goes through, and then looking at the relativistic continuity equation for the multi-time, multi-particle Dirac four-current (which seems to imply equivariance).
That's not what I suggest at all. I do not use the Dirac current. Not even for spin-1/2 particles. (See Sec. 3.4 and Appendix A of the second paper.)
 
  • #67
Demystifier said:
That's not what I suggest at all. I do not use the Dirac current. Not even for spin-1/2 particles. (See Sec. 3.4 and Appendix A of the second paper.)

I think that may be a semantic misunderstanding, because all I meant is that you use a four-current whose divergence is equal to zero, namely, the relativistic continuity equation obtained from the Dirac equation under polar decomposition (equation 17 of the first paper).
 
  • #68
Demystifier said:
Yes, but it does not introduce a PREFERRED foliation-like structure. Instead, such a structure is determined dynamically, through the choice of initial conditions.

It is analogous to the fact that a planet also defines a particular Lorentz frames (the one with respect to which it is at rest), but it does not mean that classical laws of physics describing the motion of the planet are not relativistic covariant.

But aren't you introducing an absolute simultaneity surface (a hypersurface across which all the particle positions are simultaneously defined, even at spacelike separations), by virtue of the fact that you have to synchronize the initial positions of the particles at a common time s, and that this synchronization has to hold for all future s, even when they are spacelike separated? And isn't that simultaneity surface unique?

Also, the issue (in my view at least) is not whether the equations of motion are relativistically covariant, but whether the spacetime structure introduced is consistent with "fundamental Lorentz invariance" (which I take to mean the constraints on dynamics imposed by the causal structure of Minkowski spacetime). And a simultaneity surface that introduces spacelike causal influences does not seem to me to be consistent with fundamental Lorentz invariance in that sense.

Also, when considering the possibility of nonequilibrium particle distributions in the multi-time Bohm-Dirac theory (assuming also for the moment that such a theory is in fact equivariant), I don't see anything in the synchronized trajectories approach that stops it from allowing superluminal signaling, as Valentini has demonstrated is possible with nonequilibrium particle distributions; and superluminal signaling is the most explicit violation of fundamental Lorentz invariance that I can possibly think of.
 
  • #69
Maaneli said:
I think that may be a semantic misunderstanding, because all I meant is that you use a four-current whose divergence is equal to zero, namely, the relativistic continuity equation obtained from the Dirac equation under polar decomposition (equation 17 of the first paper).
The semantic misunderstanding must be more than that, because in that paper I do not use Dirac equation, but Klein-Gordon equation.

Besides, not also that, even though I use a four-current whose divergence is equal to zero, that's not exactly the content of Eq. (17). Instead, Eq. (17) is a combination of TWO facts, one that the divergence of the four-current is zero, and the other that psi does not depend on s. In other words, the left-hand side of (3) contains two zeros, i.e., (3) is a consequence of the trivial fact that 0+0=0.

Anyway, that's not essential. The essential stuff is presented in post #64.
 
  • #70
Demystifier said:
The semantic misunderstanding must be more than that, because in that paper I do not use Dirac equation, but Klein-Gordon equation.

Crap, you're right! I must have confused the equations in your paper with those of Berndl and co.. My mistake.
 
  • #71
Maaneli said:
But aren't you introducing an absolute simultaneity surface
(a hypersurface across which all the particle positions are simultaneously defined, even at spacelike separations),
No, because n points (for each value of s) do not define u surface.

Maaneli said:
by virtue of the fact that you have to synchronize the initial positions of the particles at a common time s,
The parameter s is not time.

Maaneli said:
and that this synchronization has to hold for all future s,
The synchronization changes with s.

Maaneli said:
And isn't that simultaneity surface unique?
No, for two reasons. First, because n points do not define a surface uniquely. Second, because even these n points depend on the initial conditions at s=0.

Maaneli said:
Also, the issue (in my view at least) is not whether the equations of motion are relativistically covariant, but whether the spacetime structure introduced is consistent with "fundamental Lorentz invariance" (which I take to mean the constraints on dynamics imposed by the causal structure of Minkowski spacetime).
"Fundamental Lorentz invariance" is not the same as constraints on dynamics imposed by the causal structure of Minkowski spacetime. At least, your terminology is not standard.

Maaneli said:
Also, when considering the possibility of nonequilibrium particle distributions in the multi-time Bohm-Dirac theory (assuming also for the moment that such a theory is in fact equivariant), I don't see anything in the synchronized trajectories approach that stops it from allowing superluminal signaling, as Valentini has demonstrated is possible with nonequilibrium particle distributions;
With that I agree.

Maaneli said:
and superluminal signaling is the most explicit violation of fundamental Lorentz invariance that I can possibly think of.
As I already explained, here you are using a non-standard terminology. Lorentz invariance is the principle that the laws of physics do not depend on the choice of the Lorentz frame of coordinates. That's all. Superluminal signaling is consistent with Lorentz invariance.

See again the first Objection and Response in the attachment of post #109 in
https://www.physicsforums.com/showthread.php?t=354083
 
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  • #72
Demystifier said:
Yes, but it does not introduce a PREFERRED foliation-like structure.

agreed.

(never stated "preferred", anyway)

Maaneli said:
I've read the first paper before, and I liked it very much. But I still don't understand how you've managed to get around the need for a preferred frame "or" spacetime foliation, in your effort to construct a fundamentally Lorentz invariant deBB dynamics.

just juxtaposed by you.
 
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  • #73
Demystifier said:
No, because n points (for each value of s) do not define u surface.

But the parameter s must be a universal value for the world lines of the n points to be synchronized. And if that is the case, then for any instant of s, there exists a spacelike simultaneity hypersurface across which the synchronized particles co-determine each others velocities.

Demystifier said:
The parameter s is not time.

But as a "joint parameter", it plays precisely the role of a universal time parameter for the evolution of the particle spacetime coordinates. Yes, I realize that the wavefunction on configuration spacetime doesn't depend on s, but that doesn't mean that s cannot also be interpreted as a time parameter (even if it is a fictitious one).

Demystifier said:
As I already explained, here you are using a non-standard terminology. Lorentz invariance is the principle that the laws of physics do not depend on the choice of the Lorentz frame of coordinates.

Lorentz invariance is already implied by constraining particle dynamics with the causal structure of Minkowski spacetime. As for my criterion for "fundamental Lorentz invariance" being non-standard, maybe so, but I know other researchers in the field (Valentini, Towler, and Tumulka) who I think would agree with it. Moreover, there exist relativistic pilot-wave theories that only make use of the causal structure of Minkowski spacetime in defining the particle dynamics, and are regarded as concrete examples of pilot-wave theories that achieve fundamental Lorentz invariance. Examples include Euan Squires' local light-cone synchronization model, and the nonlocal model by Tumulka and Goldstein which makes use of opposite arrows of time on the light-cones of N-particles.

Demystifier said:
Superluminal signaling is consistent with Lorentz invariance.

See again the first Objection and Response in the attachment of post #109 in
https://www.physicsforums.com/showthread.php?t=354083

Superluminal signaling by tachyons (which you discuss in that O an R paper as an example of why superluminal signaling is compatible with special relativity) is indeed consistent with Lorentz invariance, but only because tachyons are specifically predicted by the equations of special relativity. By contrast, the possibility of nonequilibrium particle distributions, and the possible superluminal signaling that results from such distributions, is not specifically predicted by the equations of special relativity, nor does it have any relation to tachyons. Moreover, unlike tachyons, superluminal signaling by quantum nonequilibrium violates the causal structure of Minkowski spacetime.

Also, you mentioned something in that O and R paper about superluminal signaling in a QFT being undetectable at the macroscopic classical level, because quantum correlations are destroyed by decoherence. But any pilot-wave theory with a preferred frame or a foliation-like structure (including the synchronized trajectories approach) permits the possibility of the superluminal signaling from nonequilibrium matter distributions being detectable at the macroscopic classical level.
 
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  • #74
Demystifier said:
Yoda jedi and Maaneli,

The question of equivariant probability density is indeed the crucial question. My answer to this question is better explained in my second paper
http://xxx.lanl.gov/abs/0904.2287 [to appear in Int. J. Mod. Phys. A]
Appendix B.
The point is the following. There is no equivariance in the sense of Eq. (127). However, there IS equivariance in the sense of Eq. (125).
Berndl et al consider only the equivariance of the form of (127) [actually generalized to the case of many particles] and do not consider the equivariance of the form of (125) [which can also be generalized to the case of many particles]. Therefore, their conclusion that there is no equivariance has only a partial validity. The crucial difference between (127) and (125) is that the latter treats time and space on an equal footing (which is very relativistic in spirit), while the former does not treat time and space on an equal footing.

To conclude, my claim is that time should be treated on an equal footing with space, and that this, among other things, solves the problem of equivariance.

Seems reasonable, except that Berndl et al also consider the velocity equation (33)/(34), which is equivalent in form to (123) in your paper, and has an associated probability density that does treat time and space on equal footing. They also conclude that (33)/(34) is statistically transparent, and that they will elaborate on this in a future paper (but unfortunately they never did).
 
  • #75
Maaneli said:
But the parameter s must be a universal value for the world lines of the n points to be synchronized. And if that is the case, then for any instant of s, there exists a spacelike simultaneity hypersurface across which the synchronized particles co-determine each others velocities.
That is true. However, my point is that there is an INFINITE number of such hypersurfaces. Neither of them is preferred. Moreover, you don't need such a hypersurface at all to calculate the trajectories or anything else.


Maaneli said:
But as a "joint parameter", it plays precisely the role of a universal time parameter for the evolution of the particle spacetime coordinates. Yes, I realize that the wavefunction on configuration spacetime doesn't depend on s, but that doesn't mean that s cannot also be interpreted as a time parameter (even if it is a fictitious one).
You are right. The parameter s can be interpreted as a sort of time. However, this is more like Newton absolute time, note like Einstein relativistic time. That's what I meant when I said that "s is not time". Note also that the separation between different points on a single Bohmian trajectory may be spacelike in some cases, which is another reason why it may be misleading to call it "time".

Maaneli said:
Lorentz invariance is already implied by constraining particle dynamics with the causal structure of Minkowski spacetime.
I would say that Lorentz invariance is a necessary but not sufficient assumption to constrain particle dynamics with the causal structure of Minkowski spacetime. Would you agree with that?

Maaneli said:
By contrast, the possibility of nonequilibrium particle distributions, and the possible superluminal signaling that results from such distributions, is not specifically predicted by the equations of special relativity, nor does it have any relation to tachyons. Moreover, unlike tachyons, superluminal signaling by quantum nonequilibrium violates the causal structure of Minkowski spacetime.
Well, all my discussion is (tacitly) restricted to the case of quantum equilibrium.

Maaneli said:
Also, you mentioned something in that O and R paper about superluminal signaling in a QFT being undetectable at the macroscopic classical level, because quantum correlations are destroyed by decoherence. But any pilot-wave theory with a preferred frame or a foliation-like structure (including the synchronized trajectories approach) permits the possibility of the superluminal signaling from nonequilibrium matter distributions being detectable at the macroscopic classical level.
True, but as I said, all my discussion is (tacitly) restricted to the case of quantum equilibrium.
 
  • #76
Maaneli said:
Seems reasonable,
I'm glad that you think so, because it is the most important part of my idea.

Maaneli said:
except that Berndl et al also consider the velocity equation (33)/(34), which is equivalent in form to (123) in your paper, and has an associated probability density that does treat time and space on equal footing.
I wouldn't say it is really equivalent. The crucial difference is that their v^0 is positive, while my v^0 does not need to be.

Maaneli said:
They also conclude that (33)/(34) is statistically transparent, and that they will elaborate on this in a future paper (but unfortunately they never did).
Their statistical transparency is a consequence of the crucial difference above. The problem with it is that their (33)/(34) do not work for bosons.
 
  • #77
Demystifier said:
I would say that Lorentz invariance is a necessary but not sufficient assumption to constrain particle dynamics with the causal structure of Minkowski spacetime. Would you agree with that?

Well, I would say it depends on what precisely you mean by Lorentz invariance. If you mean *fundamental* Lorentz invariance, then I would say it depends on what you mean by fundamental Lorentz invariance. And it seems that you and I have different notions of what fundamental Lorentz invariance could mean exactly. Perhaps this is not so surprising, as Berndl et al. point out that it is notoriously difficult to make the notion of fundamental Lorentz invariance precise. Nevertheless, I will reiterate that fundamental Lorentz invariance (in my view) is the Lorentz invariance implied by the causal structure of Minkowski spacetime in classical Einstein-Minkowski special relativity, and not simply invariance of the equations of motion under coordinate transformations. (After all, when it is asked whether deBB theory is fundamentally compatible with "special relativity", the latter is generally implied to mean the classical Einstein-Minkowski formulation of special relativity, where Lorentz invariance of the equations of motion is a consequence of the structure of Minkowski spacetime, rather than some independent constraint on the equations of motion). And any quantum theory which is fundamentally Lorentz invariant must, by this definition, be consistent with and keep the causal structure of Minkowski spacetime unmodified and unappended (e.g. Sutherland's causally symmetric Bohm model). Hence, any quantum theory which modifies or appends the causal structure of Minkowski spacetime (whether by a preferred foliation or a foliation-like synchronization parameter) is not fundamentally Lorentz invariant.

By the way, after our first set of exchanges, I found a paper by Tim Maudlin in "Bohmian Mechanics and Quantum Theory: An Appraisal" where he essentially shares and defends my view on the meaning of fundamental Lorentz invariance. It is entitled, "Space-Time in the Quantum World":

http://books.google.com/books?id=EF...&resnum=4&ved=0CBoQ6AEwAw#v=onepage&q&f=false

Maudlin's views in that paper are encapsulated in the following statements:

In saying that we ought to frame the [relativistic constraint in terms of space-time structure, I also mean to rule out formulations based on coordinate transformations. This point is often overlooked because inconsistency with Special Relativistic space-time structure (i.e. Minkowski space-time) turns out to be equivalent to invariance under the Lorentz transformations.

and

So Lorentz invariance turns out to be a roundabout route to a more fundamental property: the essential fact about Lorentz invariant theories is that their dynamics depend only on the Special Relativistic metrical structure.


Demystifier said:
Well, all my discussion is (tacitly) restricted to the case of quantum equilibrium.

In that case, it will be very interesting to see how superluminal signaling and all that jazz will work if you allow for nonequilibrium distributions. You mentioned that in your theory, there are an infinite number of spacelike simultaneity hypersurfaces across which the synchronized particles co-determine each others velocities. So will the superluminal signaling occur along all of those hypersurfaces? And would you still regard superluminal signaling in your theory as consistent with your definition of fundamental Lorentz invariance? If not, would you then assert that your theory is only fundamentally Lorentz invariant (by your definition) in the special case of quantum equilibrium?
 
  • #78
Maaneli, you are correct that I use a different definition of "fundamental" Lorentz invariance than you (and Maudlin) do. Let me refer to this (your and Maudlin's) definition as CAUSAL Lorentz invariance.

You are also correct that my theory is not causal Lorentz invariant.

However, my point is that I do not see any particular motivation for retaining causal Lorentz invariance. For me, the only reason why I want Lorentz invariance is SYMMETRY, so for me the covariance with respect to coordinate transformations and the absence of a preferred frame is enough. Let me refer to it as SYMMETRY Lorentz invariance.

Let us also not use the unfair and vague expression "fundamental" Lorentz invariance any more.

Now let me answer you questions, having the definitions above in mind.

"So will the superluminal signaling occur along all of those hypersurfaces?"
- Yes.

"And would you still regard superluminal signaling in your theory as consistent with your definition of fundamental Lorentz invariance?"
- I would regard it consistent with symmetry Lorentz invariance.
 
  • #79
Maaneli said:
So Lorentz invariance turns out to be a roundabout route to a more fundamental property: the essential fact about Lorentz invariant theories is that their dynamics depend only on the Special Relativistic metrical structure.
This is a nonsense. No dynamical theory in physics depends ONLY on the Special Relativistic metrical structure. They all depend on something additional as well. Perhaps he meant something else here, but I cannot figure out what.

Consider, for example, electromagnetic field. It certainly depends on something which is not the principle of Special Relativistic metrical structure. Let us also consider a particular solution of Maxwell equations. For a particular solution, there may exist a particular Lorentz frame in which only electric field is nonzero, while magnetic field is zero. Would you say that this means that Maxwell theory is not "fundamentally" Lorentz invariant? I hope you would not.
 
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  • #80
Demystifier said:
Consider, for example, electromagnetic field. It certainly depends on something which is not the principle of Special Relativistic metrical structure. Let us also consider a particular solution of Maxwell equations. For a particular solution, there may exist a particular Lorentz frame in which only electric field is nonzero, while magnetic field is zero.

Yeah, the specification of initial and boundary conditions on the field. But even those conditions are constrained by the SR metrical structure.
 
  • #81
Maaneli said:
Yeah, the specification of initial and boundary conditions on the field. But even those conditions are constrained by the SR metrical structure.
The ONLY constraint (by the SR metrical structure) on initial conditions (in classical electrodynamics) is that the conditions must be specified on a hypersurface which is SPACELIKE.

By contrast, in the relativistic covariant (RC) version of Bohmian mechanics (BM), there is no such constraint. But in a sense, the absence of such a constraint makes the theory even "more relativistic", in the sense that the difference between space and time is even "more relative", or more precisely that time is treated on an equal footing with space.

But perhaps the best way to explain in what sense RC BM is Lorentz invariant is through analogy with the textbook nonrelativistic BM. Namely, nonrelativistic BM is invariant with respect to rotations in 3-dimensional space (group SO(3)). Whatever you call this form of invariance ("fundamental", "non-fundamental", "symmetry", "covariance", ... whatever) in nonrelativistic BM, RC BM is invariant with respect to Lorentz transformations in 4-dimensional spacetime (group SO(1,3)) IN EXACTLY THE SAME SENSE. In other words, you have the following symmetries:
- nonrelativistic BM: SO(3)
- RC BM: SO(1,3)
and this is essentially THE ONLY difference between nonrelativistic BM and RC BM. You obtain RC BM from nonrelativistic BM by a replacement SO(3) -> SO(1,3).
 
  • #82
Also a comment on the Valentini's idea that nonequilibrium BM may be used for superluminal signalling. Recently I have found a way to use nonlocal correlations for superluminal signalling EVEN IN EQUILIBRIUM:
http://xxx.lanl.gov/abs/1006.0338
And it works equally well in the Bohmian and the many-world interpretation.

I would like to see your opinion.
 
  • #83
To further clarify the issue of relativistic BM, let me make some additional (possibly summarizing) remarks.

You start from relativistic causality as the starting requirement. From this, it follows that
1. Lorentz covariance can be derived from it.
2. Time is NOT treated on an equal footing with space.

On the other hand, I start from SO(1,3) symmetry group for spacetime as the starting requirement. From this, it follows that
1. Lorentz covariance can be derived from it.
2. Time SHOULD be treated on an equal footing with space if no further axioms are introduced.
3. Relativistic causality does not need to be obeyed.

So in essence, you insist on relativistic causality, which is inconsistent with treating time on an equal footing with space. By contrast, I insist on treating time on an equal footing with space, which, in general, is inconsistent with relativistic causality. One cannot have both, so one must decide. In BM, only the second option seems possible.

Calling one of the two approaches "fundamental" does not help.
 
  • #84
Demystifier said:
The ONLY constraint (by the SR metrical structure) on initial conditions (in classical electrodynamics) is that the conditions must be specified on a hypersurface which is SPACELIKE.

I don't see why this is inconsistent with Maudlin's statement. But perhaps it helps to elaborate on what Maudlin said before and after that statement of his:

Minkowski space-time is homogeneous and, with respect to all time-like (or spacelike) directions, isotropic. Like Euclidean space, Minkowski space-time admits of global rectilinear orthogonal coordinate systems. Since the space-time is homogeneous, the space-time structure itself looks the same when expressed in a coordinate dependent form relative to rectilinear orthogonal coordinate systems whose origins are shifted with respect to one another. And since it is isotropic (in the time-like directions), the space-time structure also is the same when expressed in a coordinate dependent form relative to rectilinear orthogonal coordinate systems whose time axes are rotated with respect to one another. (And similarly for rotations of the spatial axes.) This means that the metric, expressed in terms of the coordinates, takes the same functional form for all Lorentz frames, and hence is invariant under the Lorentz transformations. This invariance is a consequence of the global symmetries of the metrical structure of Minkowski space-time. Any theory which is invariant under those same transformations displays the same symmetries, and so does not postulate any new space-time structure. So Lorentz invariance turns out to be a roundabout route to a more fundamental property: the essential fact about Lorentz invariant theories is that their dynamics depend only on the Special Relativistic metrical structure. And once put this way, all reference to coordinate systems and coordinate transformations may be dropped. Given, for example, a coordinate-free formulation of a theory, we may ask whether it postulates only the relativistic space-time structure or whether it posits more.


Demystifier said:
the difference between space and time is even "more relative", or more precisely that time is treated on an equal footing with space.

Can you explain again what exactly you mean by 'treating time on an equal footing with space'? Do you just mean treating time as another spatial coordinate (such as in the 4-vector), and associating a linear operator with it?


Demystifier said:
But perhaps the best way to explain in what sense RC BM is Lorentz invariant is through analogy with the textbook nonrelativistic BM. Namely, nonrelativistic BM is invariant with respect to rotations in 3-dimensional space (group SO(3)). Whatever you call this form of invariance ("fundamental", "non-fundamental", "symmetry", "covariance", ... whatever) in nonrelativistic BM, RC BM is invariant with respect to Lorentz transformations in 4-dimensional spacetime (group SO(1,3)) IN EXACTLY THE SAME SENSE. In other words, you have the following symmetries:
- nonrelativistic BM: SO(3)
- RC BM: SO(1,3)
and this is essentially THE ONLY difference between nonrelativistic BM and RC BM. You obtain RC BM from nonrelativistic BM by a replacement SO(3) -> SO(1,3).

If by "textbook [is there even a textbook version?] nonrelativistic BM" you mean the first-order pilot-wave dynamics, then yes, its dynamics is invariant under rotations in Euclidean 3-space. But perhaps it is also worth recognizing that this invariance is a consequence of the theory's natural kinematics being actually Aristotelian, rather than Galilean. And this difference, one could argue, makes it unnatural to force Lorentz invariance onto the theory.
 
  • #85
Demystifier said:
Also a comment on the Valentini's idea that nonequilibrium BM may be used for superluminal signalling. Recently I have found a way to use nonlocal correlations for superluminal signalling EVEN IN EQUILIBRIUM:
http://xxx.lanl.gov/abs/1006.0338
And it works equally well in the Bohmian and the many-world interpretation.

I would like to see your opinion.

Sounds eyebrow raising. But unfortunately, I can't read it because the PDF link is not working for me.
 
  • #86
Demystifier said:
However, my point is that I do not see any particular motivation for retaining causal Lorentz invariance. For me, the only reason why I want Lorentz invariance is SYMMETRY, so for me the covariance with respect to coordinate transformations and the absence of a preferred frame is enough.

Well, the advantages of retaining causal Lorentz invariance, and the potential problems with symmetry Lorentz covariance are pointed out by Maudlin:

The advantage of a coordinate-free formulation of compatibility with Relativity is twofold. First, it is immediately extendible to General Relativity. One can ask whether the dynamics of a theory postulate more than the metrical structure of a General Relativistic space-time just as one can ask for Minkowski space-time. Formulations in terms of invariance of coordinate based theories under transformations between rectilinear orthogonal reference systems cannot be extended to the General Relativistic context, where no such reference frames exist. Lacking the global symmetries of the Special Relativistic metric, no invariance can guarantee compatibility with relativistic space-time.

But the deeper advantage of the elimination of criteria based on coordinate transformations is simply that coordinate systems do not, in any deep sense, exist. My room may be fully of air molecules and electromagnetic fields, but is not criss-crossed by coordinate curves. Insofar as coordinate systems can be given any physical significance, it is either directly by appeal to the space-time structure (as one can define rectilinearity and orthogonality, and hence rectilinear orthogonal systems by appeal to the metrical structure) or else by appeal to the (possible or actual) results of assigning numbers to space-time points by using, for example, clocks and rods.


Demystifier said:
Let us also not use the unfair and vague expression "fundamental" Lorentz invariance any more.

OK.
Demystifier said:
"So will the superluminal signaling occur along all of those hypersurfaces?"
- Yes.

This is odd. Are you saying that superluminal signaling occurs *simultaneously* along all those hypersurfaces? Or just that the hypersurface along which the signaling occurs is frame-dependent, and that signaling can be observed along anyone of the hypersurfaces, given the appropriate reference frame? If the former, then it sounds like superluminal signaling from nonequilibrium could provide an operational definition of absolute simultaneity for ALL reference frames (which of course contradicts the relativity of simultaneity). And if the latter, then I think your theory could run into certain ontological paradoxes like those found by Maudlin in Fleming's hyperplane-dependent relativistic QM, where photons can have a certain polarization with respect to one reference frame, but no such polarization with respect to another reference frame.
 
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  • #87
Maaneli said:
So Lorentz invariance turns out to be a roundabout route to a more fundamental property: the essential fact about Lorentz invariant theories is that their dynamics depend only on the Special Relativistic metrical structure. And once put this way, all reference to coordinate systems and coordinate transformations may be dropped. Given, for example, a coordinate-free formulation of a theory, we may ask whether it postulates only the relativistic space-time structure or whether it posits more. [/B][/I]
Good! Because the covariant BM I am talking about depends only on the special relativistic metrical structure (except, of course, for the initial conditions) and can be written in a coordinate-free formulation. (If you want me to explicitly write it this way, I will do it for you after you write for me the nonrelativistic BM in 3-space-coordinate-free formulation.)

Maaneli said:
Can you explain again what exactly you mean by 'treating time on an equal footing with space'?
I have explained it elsewhere. See
http://xxx.lanl.gov/abs/1002.3226
page 5, item 2)

Maaneli said:
But perhaps it is also worth recognizing that this invariance is a consequence of the theory's natural kinematics being actually Aristotelian, rather than Galilean. And this difference, one could argue, makes it unnatural to force Lorentz invariance onto the theory.
Being natural or not, I claim that it is possible.
 
  • #88
Maaneli said:
Sounds eyebrow raising. But unfortunately, I can't read it because the PDF link is not working for me.
Write arXiv:1006.0338 in Google!
 
  • #89
Maaneli said:
Are you saying that superluminal signaling occurs *simultaneously* along all those hypersurfaces? Or just that the hypersurface along which the signaling occurs is frame-dependent, and that signaling can be observed along anyone of the hypersurfaces, given the appropriate reference frame?
I think the best answer is - neither. I am saying that hypersurfaces are completely irrelevant objects here that play no role in the formulation of the theory. I have already explained it to you few months ago in this thread. Superluminal signalling does not occur along hypersurfaces. It occurs between pointlike particles. It is much easier to understand all this if you look at the EQUATIONS that define the theory and try to figure out by yourself what these equations really mean. Then it will become clear to you why it is more confusing than useful to think in terms of hypersurfaces.
 
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  • #90
Or let me use an analogy with nonrelativistic BM. A point is space is denoted as r=(x,y,z). Consider two particles with space positions {\bf r}_1 and {\bf r}_2 at a given time t. There is a Cartesian frame (given by a rotation of the original Cartesian frame) in which {\bf r}_1 and {\bf r}_2 have the same value of z. In this frame, we say that the interaction between these two particles is z-taneous. Does it lead to any paradoxes? Does it mean there is a preferred z-coordinate? Does it mean there is a preferred foliation of space into 2-surfaces? Whatever your answer is, the same answer applies to analogous questions in relativistic-covariant BM. And if you still don't get it, then look at the equations of relativistic-covariant BM again.
 
  • #91
Demystifier said:
Good! Because the covariant BM I am talking about depends only on the special relativistic metrical structure (except, of course, for the initial conditions)

Well I'm not so sure that it depends only on the special relativistic metrical structure. You have to use a foliation-like structure, namely, a synchronization parameter, to preserve the Lorentz covariance of the particle dynamics. And this synchronization parameter is something additional to the SR metrical structure, rather than something naturally implied by the SR metrical structure.
Demystifier said:
... and can be written in a coordinate-free formulation. (If you want me to explicitly write it this way, I will do it for you after you write for me the nonrelativistic BM in 3-space-coordinate-free formulation.)

Unless you have some specific point to make (in which case, please just be explicit about it), I don't understand why you're asking me to write down said nonrelaivistic deBB formulation. The discussion here is about relativistic deBB theories. And I am not the one claiming to have a formulation of deBB theory which is compatible with SR. I am simply pointing out a condition that I think any such alleged theory should satisfy. Namely, I share the view of Maudlin that

A theory is compatible with Relativity if it can be formulated without ascribing to space-time any more or different intrinsic structure than the (special or general) relativistic metric.


On the other hand, you have a different view, in which you reject the idea of using only the intrinsic structure of the (special or general) relativistic metric, in order to claim that a (deBB) theory is compatible with Relativity. And you claim to have a covariant deBB theory which you say you can write in a coordinate-free formulation, and which thus shares the advantages of a coordinate-free formulation of SR (as characterized by Maudlin). Fine. Then show us how you do it, and show us that it is consistent with general covariance. That, I think, would significantly help the plausibility of your theory.
Demystifier said:
I have explained it elsewhere. See
http://xxx.lanl.gov/abs/1002.3226
page 5, item 2)

Thanks, that's what I thought it meant. And in that case, I would argue that, contrary to your summary point #2 in your post #83, a theory which is 'causally Lorentz invariant' does indeed treat space and time on equal footing. An example of such a theory is this:

Two Arrows of Time in Nonlocal Particle Dynamics
Authors: Roderich Tumulka
http://lanl.arxiv.org/abs/quant-ph/0210207
Demystifier said:
Being natural or not, I claim that it is possible.

Yes, but lots of things are possible in physics. What's important, IMHO, is how plausibly you can motivate the reasons for retaining symmetry Lorentz invariance.
 
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  • #92
Demystifier said:
Write arXiv:1006.0338 in Google!

No worries, I acquired a copy shortly after I wrote that. I'll get back to you on it when I have time to read it.
 
  • #93
Demystifier said:
I think the best answer is - neither. I am saying that hypersurfaces are completely irrelevant objects here that play no role in the formulation of the theory. I have already explained it to you few months ago in this thread. Superluminal signalling does not occur along hypersurfaces.

Now hang on - In an earlier post of yours, you replied to my question "So will the superluminal signaling occur along all of those hypersurfaces?" with an unqualified *yes*. Did you just not read the question I asked before you answered it?
Demystifier said:
It occurs between pointlike particles. It is much easier to understand all this if you look at the EQUATIONS that define the theory and try to figure out by yourself what these equations really mean. Then it will become clear to you why it is more confusing than useful to think in terms of hypersurfaces.

OK, if I look at the equations, particularly the trajectory equation for X_a(s), it would seem that I could draw those trajectories on a spacetime-like diagram, where the universal parameter s is on the y-axis and the particle position 4-vector X is on the x-axis. For an N particle system, X_a, it would seem that I could then draw a unique simultaneity hypersurface across the particle velocities are instantaneously co-determined, just as one can do so in the standard Bohm-Dirac theory where the universal time t is analogous to s, and the position 3-vector x_a is analogous to X_a. But I guess you would say that such a spacetime-like diagram is only fictitious, and that the real particle dynamics is seen in spacetime where there is no such hypersurface. OK, so now the fact that superluminal signaling occurs in spacetime between pointlike particles would seem to violate the relativity of simultaneity (in the sense that if I make a standard quantum measurement of the spin orientation of a particle A which is entangled with a space-like separated particle B, the latter of whose spin orientation is being continuously monitored with a nonequilibrium pointer, I will see an instantaneous change in the spin orientation of B, and this will look the same regardless of what Lorentz frames I choose for A and B). So in that sense, (and correct me if you think I am wrong) it would seem that your theory is not compatible with all the postulates of special relativity, when you allow for nonequilibrium distributions.
 
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  • #94
Maaneli said:
Well I'm not so sure that it depends only on the special relativistic metrical structure. You have to use a foliation-like structure, namely, a synchronization parameter, to preserve the Lorentz covariance of the particle dynamics. And this synchronization parameter is something additional to the SR metrical structure, rather than something naturally implied by the SR metrical structure.
No, there is no foliation-like structure. The synchronization parameter is NOT something additional to the SR metrical structure, just as time in nonrelativistic BM is NOT something additional to the 3-space rotational-symmetry structure. Read my post #90. There is no much point is answering your other questions before you understand this. I am convinced that, when you understand this, you will withdraw most of your other questions.
Maaneli said:
Unless you have some specific point to make (in which case, please just be explicit about it), I don't understand why you're asking me to write down said nonrelaivistic deBB formulation. The discussion here is about relativistic deBB theories. And I am not the one claiming to have a formulation of deBB theory which is compatible with SR.
You just don't get it. My point is that relativistic-covariant BM in 4-dimensional spacetime is ANALOGOUS to nonrelativistic BM in 3-dimensional space. I am just trying to make you understand this ANALOGY, because when you do, you will suddenly say: "Oh, THAT is what you meant. Now I get it. In fact, it is trivial." But it is essential that you see this analogy by yourself, while I can only guide you in the right direction. And at the moment, it seems to me that you don't have a clue what I am talking about, because you are not able to see the analogy. And that is probably because you are unable to think of time as just another "space" coordinate.

To help you think in the correct way, let me suggest you a mental trick. For a moment, FORGET that the spacetime metric has the form (+---). Instead , think of metric as just any metric, which can be (++++), (++--), or whatever. In fact, simply don't think about metric at all. Just pretend that you have a 4-dimensional space with some unspecified metric. Or if it is easier for you, just pretend that the metric is (++++). And forget that one of the coordinates is called "time". (Who cares about names, anyway?) And NOW try to understand again what equations of relativistic-covariant BM are actually saying. This trick works for many physicists, so it could work for you as well.
 
  • #95
One additional way to guide your thinking. Don't think about special relativity as Einstein did in 1905. Think about special relativity as Minkowski did few years later. When Minkowski discovered the spacetime view of the Einstein special theory of relativity, Einstein was not able to see much sense in it. It took a lot of time before Einstein understood the advantage of the Minkowski spacetime view. But when he finally did, it open the door for discovering general relativity. Without Minkowski view, Einstein would never discover general relativity.

Likewise, it is impossible to understand relativistic-covariant BM using only Einstein 1905 view of special relativity. Time is the 4-th dimension, and it is Minkowski, not Einstein, who first understood it. Without FULLY appreciating the point that time is (almost) nothing but the 4-th dimension, it is impossible to fully understand relativistic-covariant BM. If you say "Yes, I know that time is the 4-th dimension, but still time is not really the same as space." - then you probably don't get it yet. Try the mental trick in my previous post above.
 
  • #96
If you want to understand the source of relativity, then you must understand the quaternion waltz c = ab/a. With real's and complex numbers c equals b, but with quaternions and octonions the imaginary part of b is affected. In quaternionic Hilbert space the combination of a unitary transform (that moves the state around in Hilbert space) and an observation of position always involves a quaternion waltz! So it must be fundamental to physics. When you analyse the effects then you will discover the source of relativity!
 
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  • #97
Maaneli said:
So in that sense, (and correct me if you think I am wrong) it would seem that your theory is not compatible with all the postulates of special relativity, when you allow for nonequilibrium distributions.
Maybe it is not compatible with all postulates of the original 1905 Einstein special theory of relativity. But I don't care much about the 1905 formulation, as long as I have a formulation which I find much better, such as Minkowski formulation I mentioned in the post above. The theory of relativity neither started nor ended with Einstein.

For a difference between different views of relativity, see also the Mike Towler lectures on deBB.
 
  • #98
You can specify an infinite dimensional separatable Hilbert space over the real's, the complex numbers, the quaternions and according to Horwitz with some trouble also over the octonions. Quantum logical propositions can be represented in the closed subspaces of such a Hilbert space. It is an enlightening experience to try to prove "All items in universe influence each other's positions" by implementing this in the Hilbert space. You must first implement the items, then the position of the items. Next the universe of items and finally the influences. In this way you will encounter many aspects of quantum physics. If you do it properly, then you will find the source of gravity.

See http://www.scitech.nl/English/Science/Exampleproposition.pdf
 
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  • #99
Maaneli said:
Yes, but lots of things are possible in physics. What's important, IMHO, is how plausibly you can motivate the reasons for retaining symmetry Lorentz invariance.
Plausibility is a subjective thing. Some find the collapse postulate plausible, some don't. Some find nonrelativistic BM plausible, some don't. Likewise, some find symmetry Lorentz invariance plausible (see e.g. http://xxx.lanl.gov/abs/1006.5254), some don't.

It is up to me to explain why it is plausible TO ME, but it is up to the others to decide if it is also plausible TO THEM. I cannot ask from others to accept that it is plausible. But at least I can ask from others to understand my ideas properly.
 
  • #100
Maaneli said:
Now hang on - In an earlier post of yours, you replied to my question "So will the superluminal signaling occur along all of those hypersurfaces?" with an unqualified *yes*. Did you just not read the question I asked before you answered it?
When I said "Yes", I made a mistake by accepting your suggestion to talk in the language of hypersurfaces. This is an unnatural language for the theory, which makes it easy to say something inconsistent when you try to use this language. The theory does not contain hypersurfaces. Thus, even though it is not impossible to talk about this theory in terms of hypersurfaces (which I tried), it makes more confusion than clarification. I will try to avoid it in the further discussions.

Roughly, it reminds me to explanations of special relativity (in classical mechanics) in terms of a preferred Lorentz frame. As Lorentz has shown, it is possible as well (the Lorentz "eather"). Yet, it introduces more confusion than clarification. It is a very unnatural way to talk about special relativity and it is better to avoid it.
 
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