Consensus about Non-Locality & Spacetime

[Ken G]

What I'd like to know is whether Demystifier is claiming that treating x and t symmetrically results in a theory that says it is possible to send classical information superluminally. Since there is no experimental evidence that this is possible, that would sound like going too far to treat x and t symmetrically. After all, the main reason for treating x and t symmetrically, despite our experience to the contrary, is that doing so supports the concept of a universal speed limit. Remove that constraint, and much of the reason to want to treat x and t symmetrically also vanishes. I'm not one of those who believes that we should embed symmetries into our theories even if nature does not give us reason to, just for the sake of having a more symmetric theory. Symmetry is often associated with parsimony, but there is more than just Occam's Razor to think about when constructing theories, there are also advantages to theories that support interpretations that retain our general experiential notions.

 

[Demystifier]

My only question is how come this analogy only works if one exchanges the roles of time and space? If you don't know, Hope Nikolic himself can share. Thanks.

The argument compares two very similar arguments, one referring to a superluminal velocity
dx/dt > 1 .. (1)
the other to a subluminal velocity
dx/dt < 1 .. (2)
But note that (1) can be written as
dt/dx < 1 .. (1')
while (2) can be written as
dt/dx > 1 .. (2')
So, if we exchange the roles of space and time, i.e., if we interpret t as "space" and x as "time", then it is natural to define the velocity as dt/dx, rather than dx/dt. In this way (1') is interpreted as "subluminal" velocity, while (2') is interpreted as "superluminal" velocity. In other words, by exchanging the roles of space and time, subluminal velocities transform to superluminal velocities, and vice versa. Thus, if space and time are treated on an equal footing, then their exchange should be allowed, and then there is no fundamental difference between superluminal and subluminal velocities. In particular, if subluminal velocities are compatible with relativity, then so are superluminal ones.

I hope it's clearer now.

 

[Demystifier]

What I'd like to know is whether Demystifier is claiming that treating x and t symmetrically results in a theory that says it is possible to send classical information superluminally. Since there is no experimental evidence that this is possible, that would sound like going too far to treat x and t symmetrically.

I would put it this way. If x and t are treated symmetrically, then there is nothing paradoxical about sending classical information superluminally. But it does not yet mean that sending classical information superluminally is possible. We apparently cannot send classical information superluminally because the dynamics is described by a particular Lagrangian which does not allow that. If the dynamics has been described by a somewhat different relativistic-covariant Lagrangian as in
http://xxx.lanl.gov/abs/1006.1986
then sending classical information superluminally would be possible.

 

[stglyde]

The argument compares two very similar arguments, one referring to a superluminal velocity
dx/dt > 1 .. (1)
the other to a subluminal velocity
dx/dt < 1 .. (2)
But note that (1) can be written as
dt/dx < 1 .. (1')
while (2) can be written as
dt/dx > 1 .. (2')
So, if we exchange the roles of space and time, i.e., if we interpret t as "space" and x as "time", then it is natural to define the velocity as dt/dx, rather than dx/dt. In this way (1') is interpreted as "subluminal" velocity, while (2') is interpreted as "superluminal" velocity. In other words, by exchanging the roles of space and time, subluminal velocities transform to superluminal velocities, and vice versa. Thus, if space and time are treated on an equal footing, then their exchange should be allowed, and then there is no fundamental difference between superluminal and subluminal velocities. In particular, if subluminal velocities are compatible with relativity, then so are superluminal ones.

I hope it's clearer now.

Ok, clearer now. But you also give as one of the conditions that there should be no free will. Why. Why would your model collapse if there is free will? And what is the relation of free will to treating space and time as equal and these views seemingly dependent on each other? Maybe something to do with the fact that you believe in block spacetime and nothing can ever influence it. Everything is already written from past to future? This is what can falsify your theory. We don't have to discuss what is free will (to avoid off topic and it's not necessary), but the fact whether there is free will or not can either vadliate or invalidate your theory right?
So 50 yeasr from now. If it would be proven there was really free will, then your model completely collapse.

 

[Demystifier]

Why would your model collapse if there is free will?

I have explained it in the paper, but let me repeat. If one has free will, then one can choose to send a signal one wishes to. But in my theory, that signal may travel faster than light. This means that a signal can be sent to the past. But sending a signal to the past one wishes to may be logically inconsistent (grandfather paradox).

If free will would be proven to exist, then all currently known fundamental physical theories, either deterministic or probabilistic, would collapse. That's because free will is incompatible with fundamental deterministic laws, as well as with fundamental probabilistic laws.

 

[stglyde]

I have explained it in the paper, but let me repeat. If one has free will, then one can choose to send a signal one wishes to. But in my theory, that signal may travel faster than light. This means that a signal can be sent to the past. But sending a signal to the past one wishes to may be logically inconsistent (grandfather paradox).

But it's easy to get over it. Whenever free will was used, then Preferred Foliation (Maudlin context) is invoked. There you won't have any grandfather paradox. What's so difficult about this? Note Preferred Foliation is even simpler or equally likely than your treating space and time as equal. Or you can have them both anyway with preferred foliation only used for free will.

 

[Demystifier]

But it's easy to get over it. Whenever free will was used, then Preferred Foliation (Maudlin context) is invoked. There you won't have any grandfather paradox. What's so difficult about this? Note Preferred Foliation is even simpler or equally likely than your treating space and time as equal. Or you can have them both anyway with preferred foliation only used for free will.

Yes, that's also a logical possibility, but I wouldn't call it "simpler" or "equally likely".

 

[stglyde]

Yes, that's also a logical possibility, but I wouldn't call it "simpler" or "equally likely".

How come in Copenhagen, free will can coexist with nonlocal correlations such that the randomness can't be used to send information because quantum randomness doesn't have order. Yet in Bohmian, nonlocal correlations automatically can be used to send information and cause causality paradox. Remember it is the wave function that do the trick in both so why can't we say the wave function in bohmian acts like in Copenhagen preventing the sending of sginal. I can't quite verbalize it although the reason is just on the surface of my mind. When mentioning Bohmian, please specify whether you are talking of old fashioned BM or your BM.

 

[stglyde]

How come in Copenhagen, free will can coexist with nonlocal correlations such that the randomness can't be used to send information because quantum randomness doesn't have order. Yet in Bohmian, nonlocal correlations automatically can be used to send information and cause causality paradox. Remember it is the wave function that do the trick in both so why can't we say the wave function in bohmian acts like in Copenhagen preventing the sending of sginal. I can't quite verbalize it although the reason is just on the surface of my mind. When mentioning Bohmian, please specify whether you are talking of old fashioned BM or your BM.

Oh I think I remember. Copenhagen has randomness scrambler built in so Alice and Bob wouldn't know what is really sent. So you mean if Bohmian would have randomness scrambler added, then will free and nonlocality won't imply sending information, agree with these arguments?

 

[stglyde]

Oh I think I remember. Copenhagen has randomness scrambler built in so Alice and Bob wouldn't know what is really sent. So you mean if Bohmian would have randomness scrambler added, then will free and nonlocality won't imply sending information, agree with these arguments?

Oh I remember the contextuality part. In Copenhagen, in the absence of measurement to measure its position, the particle has no position.. so with randomness scrambler built in, there was no way to affect the past because the past won't know what to measure. In Bohmian, a particle always has position, so even if you send random 1 and 0 nonlocally and superluminal, it can still affect the past by the value regardless of 1 or 0 existing... but note this only occurs in a relativistic BM. But convensional BM has no relativistic counterpart (except yours) so this causality won't even be a problem because convensional BM uses Newtonian spacetime.

Now in your time and space equal formulation of BM which you made relativistic. You have to invoke it to avoid causality effect. But you have do away with free will.

Is is impossible to create relativistic BM (with changing reference frame) without using any of your device of treating space and time as equal?

 

[Ken G]

Thus, if space and time are treated on an equal footing, then their exchange should be allowed, and then there is no fundamental difference between superluminal and subluminal velocities. In particular, if subluminal velocities are compatible with relativity, then so are superluminal ones.

The usual statement made about relativity is not that superluminal velocities are categorically impossible, but rather that crossing from subluminal to superluminal is impossible. So if there was some population of superluminal particles (tachyons), they would always be superluminal. This preserves the symmetry, yet still holds that superluminal communication is impossible, unless you get access to tachyons. So that doesn't refute BM, because BM can invoke some tachyon-like connection and still be consistent with relativity, but it's not clear that invoking new physics is justified simply to allow BM to give a consistent rendition of what is happening.

 

[Ken G]

Not to get the thread too embroiled in free will, but I should point out that I can think of at least two ways that free will is not challenged by any highly successful deterministic (or random, for that matter) theory of physics:

1) physics theories are used by intelligences to understand reality, but the understanding it generates is never complete. If we observe something that we don't understand, and other things that we do understand, we do not say that the things we do understand make impossible those we don't. The only solid definition of an "illusion" is something that can be better understood in a different way, not something that simply isn't understood at all. Arguments that successful deterministic theories require a self-delusion of free will do not offer us any better understanding of delusions of free will than they do of actual free will.

2) the nature of free will is not well defined, and certain versions of the concept are fully compatible with determinism. Determinism is about predictability, and free will can be viewed as being about the absence of constraints that would tend to influence an agent to feel forced to do something against their nature. That is certainly close to the legal definition of someone's "will", after all. In those terms, anyone who argues that deterministic theories preclude free will is arguing that people being allowed to act according to their nature must not have free will if their nature is predictable. That argument does not follow, because if someone's behavior is predictable based on their nature, and they are allowed to perform according to their nature, then we can say that acting according to their nature is what acting according to free will is actually about.

Personally, I hold to the first argument of those, so find the second argument to be unnecessary. I think we don't know enough about free will to even give it a definition that makes any contact with fundamental physics at all.

 

[Demystifier]

Is is impossible to create relativistic BM (with changing reference frame) without using any of your device of treating space and time as equal?

Perhaps it is, but probably not in such a simple (whatever that means) way.

 

[Demystifier]

The usual statement made about relativity is not that superluminal velocities are categorically impossible, but rather that crossing from subluminal to superluminal is impossible.

That's true if the mass of the particle is constant. But if mass can change, or more precisely if the sign of m^2 can change, then the particle can change its velocity from a subluminal to a superluminal one. See
http://xxx.lanl.gov/abs/1006.1986

... but it's not clear that invoking new physics is justified simply to allow BM to give a consistent rendition of what is happening.

Quite the opposite, I think it is more than justified to introduce some new physics in order to explain what is happening behind the standard "shut up and calculate" rules of QM.

 

[stglyde]

That's true if the mass of the particle is constant. But if mass can change, or more precisely if the sign of m^2 can change, then the particle can change its velocity from a subluminal to a superluminal one. See
http://xxx.lanl.gov/abs/1006.1986

Here's the problem of normal matters using tachyons and sending them which not even be possible.. anyone know any workaround for it?

By PeterDonis:

Well, there's the obvious point that the theory would violate Lorentz invariance. You would also have to work out whether it is even possible for your version of tachyons to interact with ordinary matter, and if so how. Theorists have tried to construct theories of tachyons and have found issues with doing that; for example, the straightforward way of constructing a theory of tachyons interacting with normal matter violates conservation of energy. Also, when you start bringing in quantum field theory, it turns out that you can't really use tachyons to transmit information faster than light anyway; in other words, a quantum field theory that would allow a "tachyon pistol" is not really possible. See here:

http://www.desy.de/user/projects/Physics/ParticleAndNuclear/tachyons.html

I don't know whether an "aether" theory of tachyons could overcome the above issues, because if tachyons interact with normal matter, the interaction has to be Lorentz invariant even if the tachyons by themselves could violate Lorentz invariance (because normal matter is still Lorentz invariant, at least to a very good approximation).

 

[stglyde]

Here's the problem of normal matters using tachyons and sending them which not even be possible.. anyone know any workaround for it?

By PeterDonis:

the correct link... please comment on it guys.

http://www.desy.de/user/projects/Physics/ParticleAndNuclear/tachyons.html

 

[Ken G]

That's true if the mass of the particle is constant. But if mass can change, or more precisely if the sign of m^2 can change, then the particle can change its velocity from a subluminal to a superluminal one. See
http://xxx.lanl.gov/abs/1006.1986

Fair enough, but what your paper essentially does is group together all the new physics that one would need to form a Bohmian view that is consistent with relativity. The new physics includes things like scalar potentials, absolute simultaneity, and superluminal communication. I don't dispute the value in being able to notice the possible self-consistent groupings, but I do question whether it can be claimed that a superior interpretation of existing physics appears by introducing new physics. To me, the value of an interpretation is twofold, but both are essentially subjective. First of all, an interpretation helps us understand the theories we have now, but different physicists may prefer to understand in different ways. Secondly, they can help lead to the discovery of new physics, and this is a fine thing to use BM for, but it is not a particularly strong argument for the value of BM in regard to the existing physics, as it is basically anybody's guess how the new physics will shake out (that's the subjective part-- where one wishes to devote their resources). I see all the new physics that BM needs as a problem for using it with current physics, but I also see it as a valuable contribution for getting a "heads up" toward possible new directions. These are two rather different uses for interpretations, and sometimes that landscape can get a bit confusing when various different threads overlap.

Quite the opposite, I think it is more than justified to introduce some new physics in order to explain what is happening behind the standard "shut up and calculate" rules of QM.

The problem with introducing new physics is that it steps on the distinctions between theories and interpretations of theories. BM seems to suffer from this a lot-- it cannot decide if it is just trying to be one valid way to frame existing QM, or if it is trying to assert the existence of new physics that we should be designing experiments to look for. Either is a valid course, but confusing the two isn't, because they must be judged in very different ways. Pure interpretations of QM must be judged on essentially philosophical grounds, like Occam's razor and connecting with what is already understood and so on (which can be very different for different people, who already understand different things). New theories must be judged in the time-honored way: by support from observational evidence.

 

[stglyde]

That's true if the mass of the particle is constant. But if mass can change, or more precisely if the sign of m^2 can change, then the particle can change its velocity from a subluminal to a superluminal one. See
http://xxx.lanl.gov/abs/1006.1986


Quite the opposite, I think it is more than justified to introduce some new physics in order to explain what is happening behind the standard "shut up and calculate" rules of QM.

Towards the end of http://www.desy.de/user/projects/Physics/ParticleAndNuclear/tachyons.html it is mentioned:

"The bottom line is that you can't use tachyons to send information faster than the speed of light from one place to another. Doing so would require creating a message encoded some way in a localized tachyon field, and sending it off at superluminal speed toward the intended receiver. But as we have seen you can't have it both ways: localized tachyon disturbances are subluminal and superluminal disturbances are nonlocal."

Demystifier has *really* solved this problem as well?

 

[Demystifier]

"The bottom line is that you can't use tachyons to send information faster than the speed of light from one place to another. Doing so would require creating a message encoded some way in a localized tachyon field, and sending it off at superluminal speed toward the intended receiver. But as we have seen you can't have it both ways: localized tachyon disturbances are subluminal and superluminal disturbances are nonlocal."

This refers to classical tachyonic FIELDS (i.e., extended objects), while ...

Demystifier has *really* solved this problem as well?

... my tachyonic paper mentioned in #49 is about classical tachyonic PARTICLES (i.e., pointlike objects).

Note also that in the Bohmian case (Sec. 5 of that paper), a particle which may become tachyonic at some regions of spacetime is guided by a non-tachyonic "field" (wave function).

 

[stglyde]

Perhaps it is, but probably not in such a simple (whatever that means) way.

How many are working on relativistic BM without making space and time equal and how are they progressing now? If absolutely no progress (except yours). Why do many physicists give high hope to BM when it can't be made relativistic. And what are the exact arguments why they have difficulty making it relativistic (that is, by making time as coordinate and not parameter as in Newtonian). Here let's mention standard BM versions that doesn't include yours for sake of discussions.

 

[Demystifier]

How many are working on relativistic BM without making space and time equal ...

A few.

... and how are they progressing now?

There is some progress proportional to the number of people doing it. Since that number is not big, the progress is also not very spectacular.

 

[stglyde]

Fair enough, but what your paper essentially does is group together all the new physics that one would need to form a Bohmian view that is consistent with relativity. The new physics includes things like scalar potentials, absolute simultaneity, and superluminal communication. I don't dispute the value in being able to notice the possible self-consistent groupings, but I do question whether it can be claimed that a superior interpretation of existing physics appears by introducing new physics. To me, the value of an interpretation is twofold, but both are essentially subjective. First of all, an interpretation helps us understand the theories we have now, but different physicists may prefer to understand in different ways. Secondly, they can help lead to the discovery of new physics, and this is a fine thing to use BM for, but it is not a particularly strong argument for the value of BM in regard to the existing physics, as it is basically anybody's guess how the new physics will shake out (that's the subjective part-- where one wishes to devote their resources). I see all the new physics that BM needs as a problem for using it with current physics, but I also see it as a valuable contribution for getting a "heads up" toward possible new directions. These are two rather different uses for interpretations, and sometimes that landscape can get a bit confusing when various different threads overlap.
The problem with introducing new physics is that it steps on the distinctions between theories and interpretations of theories. BM seems to suffer from this a lot-- it cannot decide if it is just trying to be one valid way to frame existing QM, or if it is trying to assert the existence of new physics that we should be designing experiments to look for. Either is a valid course, but confusing the two isn't, because they must be judged in very different ways. Pure interpretations of QM must be judged on essentially philosophical grounds, like Occam's razor and connecting with what is already understood and so on (which can be very different for different people, who already understand different things). New theories must be judged in the time-honored way: by support from observational evidence.

People have different temperaments. Some are introvert, extrovert, artistic, thinker (logic or left brained), feeler (or right brain), and I guess this has to do with their choosing different interpretations. The thinker choosing Copenhagen because they simply want to think in terms of equations. The extrovert choosing Bohmian because it is like arts, you can imagine things and the maybe the introvert Many Worlds.

About support from observational evidence. Yes what can set them apart or nail the right one is a unique prediction that only one of them can make. Is this possible? Yes.

But then physics is also about belief and holding on to current consensus. In the 15th century. Discussion of anything physics can get one burnt at stake. So deep is the damage that it has affected us profoundly in an unconscious way, because now centuries later we have to to do the opposite, accept wholly that everything is explainable by physics and anything outside it doesn't exist.

I'll give a clue what it is. If I mention the name. It can trigger primal unconscious chord and cause some sort of uncomfortableness in physicists. I'll mention the word now anyway. It's "consciousness". Due to the deep pain suffered in the 15th century. Physicists avoid it like plague. But another reason is that they think consciousness function in the levels of cells and neurons and nothing below. And it is a good deduction to make.

What we have is some kind of catch 99. We don't know the new physics below. We use that fact to argue consciousness work in the level of neurons and cells because there is no new physics below (except by those who consider something akin to Penrose-Hameroff Microtubules and Objective Collapse).

Is there none? We can't discount anything yet. But physicists are more comfortable thinking of billions and billions galaxies were once the size of a hydrogen proton than thinking about consciousness and what form and level it may take below the metric (of the mind).

In addition to consciousness. There is something else. But mere mentioning the other word can make it banned and message deleted so I'll not mention the word. A century ago, any discussion about Many Worlds can make one be put in mental institutions, now it's a bit more humane, one is simply isolated.

You may not have a clue what I'm talking about Ken. Because the word is censored.. in spite of it having evidence and can make one nail the right interpretation or rather new physics. Also if you continue to discuss on this level. This thread would even be locked so let's not talk about it and just put it under the rag.

At this point in time. Officially we can't distinguish what is the right interpretation or rather new physics because of this lack of deeper and multi disciplinary explorations.

 

[bohm2]

I'll mention the word now anyway. It's "consciousness". Due to the deep pain suffered in the 15th century. Physicists avoid it like plague. But another reason is that they think consciousness function in the levels of cells and neurons and nothing below. And it is a good deduction to make.

I'm not sure I agree about that. The problem is that many scientists argue that there's no hint of how one can get subjectivity/qualia/consciousness out a complex network of neural connections, etc. The gap between mind (the 'mental') and neurons (the 'material') (as presently understood) seems immense. They just don't seem to mesh. Consciousness seems to "provide us with a kind of ‘window’ on to our brain, making possible a transparent grasp of a tiny corner of a materiality that is in general opaque to us" but we haven't the slightest clue of how to mesh it together with what we presently call "matter". I found this Lockwood passage interesting:

Do we therefore have no genuine knowledge of the intrinsic character of the physical world? So it might seem. But, according to the line of thought I am now pursuing, we do, in a very limited way, have access to content in the material world as opposed merely to abstract casual structure, since there is a corner of the physical world that we know, not merely by inference from the deliverances of our five sense, but because we are that corner. It is the bit within our skulls, which we know by introspection. In being aware, for example, of the qualia that seemed so troublesome for the materialist, we glimpse the intrinsic nature of what, concretely, realizes the formal structure that a correct physics would attribute to the matter of our brains. In awareness, we are, so to speak, getting an insider's look at our own brain activity.

http://plato.stanford.edu/entries/neutral-monism/#7.2

Others argue that it's quite possible that our current "core" notions of "matter" (physics) may require revision to allow unification of the mental with the physical. Others argue that the problem may be intractable because of our own cognitive limitations. Maybe the problem of consciousness has its source as some special feature of consciousness, itself. By having this special access (inner experience) to it that we have to nothing else (and nothing else to us), this may not allow us to see the connection?

 

[stglyde]

The problem is that many sciemtists argue that there's no hint of how one can get subjectivity/qualia/consciousness out a complex network of neural connections, etc. The gap between mind (the 'mental') and neurons (the 'material') (as presently understood) seems immense. They just don't seem to mesh. Consciousness seems to "provide us with a kind of ‘window’ on to our brain, making possible a transparent grasp of a tiny corner of a materiality that is in general opaque to us" but we haven't the slightest clue of how to mesh it together with what we presently call "matter".

But unfortunately. Only 1% of physicists are aware of the above. Those who are not aware just censor anything that mentions that it thinking "how medieval!".

And that is the problem we are having now. Those who have access to high tech instruments like particle accelerators or SQUID or other million dollar equipment are of the 99% variety. For example Lisa Randall and Stephen Hawking are sure the mind works in the levels of cells and neurons and nothing more.

In the mind lies the key to the next physics. But I can't continue more lest this thread be locked.

 

[Ken G]

Not to get too far off track, but I would say that the "problem of consciousness" is that we don't have a scientifically framed hypothesis about what the problem of consciousness actually is. One might argue that there is a hypothesis that consciousness can be reduced entirely to the physical action of the brain tissue, but this isn't a scientific hypothesis, because it doesn't suggest an experiment that comes out A if the hypothesis is true, or B if it isn't. What does an experiment look like that refutes the claim that consciousness can be reduced entirely to the physical action of brain tissue? We need a better question than that, something that actually tells us something about consciousness.

 

[Demystifier]

The extrovert choosing Bohmian

I am an introvert personality, and yet I choose Bohmian.

http://changingminds.org/explanations/preferences/extravert_introvert.htm