Why Is the Time Symmetric Interpretation Overlooked in Quantum Discussions?

[Demystifier]

If it helps, I also think that the Aharonov time-symmetric interpretation is purely probabilistic (and therefore not deterministic), while dBB interpretation is deterministic.

 

[DrChinese]

If it helps, I also think that the Aharonov time-symmetric interpretation is purely probabilistic (and therefore not deterministic), while dBB interpretation is deterministic.

Thanks for your comment!

 

[joseph0887]

Hi,
I'm a real late comer to this thread, and a new comer to these forums in general.

Dr.Chinese I think I understand what you mean, I'll attempt to put it in my own words, maybe you could tell me if I've gone wrong:

"The Time Symmetric Interpretation cannot be called deterministic as future events cannot be predicted even with perfect knowledge of a systems past."

At this point I have 2 questions:
1. Do Time Symmetric interpretations, in redefining causality, similarly redefine determinism?
It seems related to the philosophical concept of the B theory of time.

http://plato.stanford.edu/entries/time/#TheBThe

2. Could Time Symmetric interpretations be said to be ontologically realist, rather than epistemologically realist?

Also a brief question. How does retrocausality prevent the transfer of information back in time, and the grandfather paradox? I confess the mathematics are beyond me, so I wondered if there are any appropriate analogies? Well the question is brief, an answer may not be.

Another brief question, maybe DeMystifier will answer. Do Lorentz Invariant versions of the deBB interpretation also invoke retrocausality?

Thankyou for your consideration.

 

[audioloop]

Hi,
I'm a real late comer to this thread, and a new comer to these forums in general.

Dr.Chinese I think I understand what you mean, I'll attempt to put it in my own words, maybe you could tell me if I've gone wrong:

"The Time Symmetric Interpretation cannot be called deterministic as future events cannot be predicted even with perfect knowledge of a systems past."

At this point I have 2 questions:
1. Do Time Symmetric interpretations, in redefining causality, similarly redefine determinism?
It seems related to the philosophical concept of the B theory of time.

http://plato.stanford.edu/entries/time/#TheBThe

2. Could Time Symmetric interpretations be said to be ontologically realist, rather than epistemologically realist?

Also a brief question. How does retrocausality prevent the transfer of information back in time, and the grandfather paradox? I confess the mathematics are beyond me, so I wondered if there are any appropriate analogies? Well the question is brief, an answer may not be.

Another brief question, maybe DeMystifier will answer. Do Lorentz Invariant versions of the deBB interpretation also invoke retrocausality?

Thankyou for your consideration.

...Finally, this experiment sheds a new light on the age-old question of free
will. Apparently, a measurement's anticipation of a human choice made
much later renders the choice fully deterministic, bound by earlier causes.
One profound result, however, shows that this is not the case. The choice
anticipated by the weak outcomes can become known only after that
choice is actually made. This inaccessibility, which prevents all causal
paradoxes like “killing one's grandfather,” secures human choice full
freedom from both past and future constraints...

http://arxiv.org/ftp/arxiv/papers/1206/1206.6224.pdf

 

[DrChinese]

Hi,
I'm a real late comer to this thread, and a new comer to these forums in general.

Dr.Chinese I think I understand what you mean, I'll attempt to put it in my own words, maybe you could tell me if I've gone wrong:

"The Time Symmetric Interpretation cannot be called deterministic as future events cannot be predicted even with perfect knowledge of a systems past."

At this point I have 2 questions:
1. Do Time Symmetric interpretations, in redefining causality, similarly redefine determinism?
It seems related to the philosophical concept of the B theory of time.

http://plato.stanford.edu/entries/time/#TheBThe

2. Could Time Symmetric interpretations be said to be ontologically realist, rather than epistemologically realist?

Also a brief question. How does retrocausality prevent the transfer of information back in time, and the grandfather paradox? I confess the mathematics are beyond me, so I wondered if there are any appropriate analogies? Well the question is brief, an answer may not be.

Another brief question, maybe DeMystifier will answer. Do Lorentz Invariant versions of the deBB interpretation also invoke retrocausality?

Thankyou for your consideration.

Welcome to PhysicsForums, joseph0887!

I may not be able to answer all of your (excellent) questions, but I will throw out a few things. The TS interpretations supply the answer to the question, "what is context of an observation?". The TS approach is that the context lies locally in the future. For an entangled particle pair, the only relevant information to predicting correlations is that context.

For a Bohmian type interpretation, the answer to the same question is that the context is non-local in the present. As best as I can tell, this seems to be as good an answer as with TS type interpretations.

I think of the TS group AND Bohmian types as not being realistic in the sense that the context is essential - it is not observer independent. On the other hand, many Bohmians take exception to that characterization. I believe Demystifier essentially agrees with my assessment on this.

A big difference is that Bohmian interpretations can answer (in principle) another question: what is the outcome of an experiment with a stated context? TS interpretations do not purport to provide an answer to that. Bohmian interpretations could provide the answer if the initial conditions were sufficiently known, although the same interpretation says that is not possible anyway.

So you almost end up at the same point no matter how you go about it.

 

[rocket123456]

Time symmetric interpretations do NOT restore determinism or realism (as they are normally defined). Determinism requires the past alone to influence the future.

Determinism requires only that all events that occurred were unalterable.

That is that they could never have been different to what actually manifested itself.

You do not need any casual chain.. you can have both cause and effect on the macro level and chaos at the micro-scale.. as long as all events already exist(eternalism) or must come to exist the way they did-we have determinism.

If you can replace the block-universe theory determinism would certainly be an unsubstansiated claim

Modern interpretations take the form of "non-computable" determinism and give up on laplace contention(unless maybe there is someone with precognition able to know all all future events).

Determinism should be viewed as a non-religious fatalism.

 

[Dale]

Determinism requires only that all events that occurred were unalterable.

That is that they could never have been different to what actually manifested itself.

You do not need any casual chain.

As you and I have discussed at length elsewhere, this definition of "determinism" is non-scientific. The usual scientific definition is the "causal chain" definition that you are discarding, i.e. that from knowledge of the state of the system at some point in time and the laws governing the system you can predict the state of the system at any future point in time.

The problem with your definition of "determinism" is that it is unfalsifiable. I.e. there is no possible experiment which could be performed whose outcome could be used as evidence that the universe is not deterministic. If it is unfalsifiable then it is unscientific, and if there can be no experimental evidence against a hypothesis then there can be no experimental evidence for it either.

 

[rocket123456]

Given that causality does seem to be questioned we can make things easy.

If we can show that the Newtonian view of time is correct then determinism within all definitions is false.

or is Einstein/Minkowskis block-universe unfalsifiable?

 

[Dale]

If we can show that the Newtonian view of time is correct then determinism within all definitions is false.

How so? What specific experimental outcome would show YOUR definition of determinism to be false? If your concept of determinism is indeed falsifiable, then you should clear that up, because frankly I don't see how.

Btw, it is rude to hijack someone else's thread, so you should probably return to your own or start another.

 

[rocket123456]

How so? What specific experimental outcome would show YOUR definition of determinism to be false?

the Newtonian time would prove that the future events are uncertain if we accept that causality is undermined already by QM.

The reason the lack of causal chains are not important for block-universe is because we don't know if time works differently on the microscopic level.

 

[rocket123456]

This thread is about "time" so it is by no means hijacked, it's rather highly relevant.

The individual starting this thread holds "eternalism" to be an established fact.

 

[Dale]

the Newtonian time would prove that the future events are uncertain if we accept that causality is undermined already by QM.

Sorry, I don't understand, you are mixing Newtonian mechanics and QM in a confusing way. Again, what specific experiment could be performed to disprove your version of determinism and how would that disprove it?

 

[rocket123456]

Sorry, I don't understand, you are mixing Newtonian mechanics and QM in a confusing way. Again, what specific experiment could be performed to disprove your version of determinism and how would that disprove it?

If you can show that the passage of time is genuine feature of the world irrespective of our conscioussness(there really is a universal clock ticking for the universe)

Then if we accept that casuality is not a feature for all events(as qm has led us to belive) determinism can no longer be true because the future is open in every sense of the word.

The block-time theory is usually referred to in articles by physicists so I suppose it is a scientific claim of some sort. In fact an associate professor of physics told me that it's hard to do physics without presuposing that we live in a block-universe although some still reject it.

 

[Dale]

If you can show that the passage of time is genuine feature of the world irrespective of our conscioussness(there really is a universal clock ticking for the universe)

Then if we accept that casuality is not a feature for all events(as qm has led us to belive) determinism can no longer be true because the future is open in every sense of the word.

That isn't an experiment. An experiment is the result of some specified measurement on a specific system. E.g. "simultaneiously drop 2 cannon balls of different masses from the leaning tower of Pisa and measure which one hits the ground first".

So again, what specific experimental result could be obtained, in principle, to falsify your definition of determinism? E.g. "Newtonian gravity predicts that the cannon balls will hit at the same time, so if the heavier cannon ball always hits first then Newtonian gravity is falsified".

 

[DrChinese]

This thread is about "time" so it is by no means hijacked

Time symmetry, yes. Determinism, no. Determinism does not usually speak to this point other than to say that an earlier context leads to a certain outcome at a later time. If you want to debate the meaning of determinism, eternalism, etc, a new thread is appropriate.

 

[Dale]

Determinism does not usually speak to this point other than to say that an earlier context leads to a certain outcome at a later time.

Unfortunately, rocket123456 is not using the standard scientific definition of determinism that you reference here. He is using some personal or philosophical definition which he doesn't seem to realize is deeply flawed from a scientific perspective since it is non-falsifiable.

 

[rocket123456]

Unfortunately, rocket123456 is not using the standard scientific definition of determinism that you reference here. He is using some personal or philosophical definition which he doesn't seem to realize is deeply flawed from a scientific perspective since it is non-falsifiable.

"Timeless reality" by Victor Stenger is the exakt same propositon of a universe without any time and thus no coming into being- which entails that the uncertainty is only superfical.

Maybe it's not falsifiable but it's true. Why do public intellectuals keep talking about my block-universe determinism if it's deeply flawed

By the way Lawrence Krauss claims(correctly) that all versions of QM are deterministic in this clip:

at 2:09:30

 

[Dale]

Maybe it's not falsifiable but it's true.

So what? I have never made a claim that it is false.

It is unfalsifiable, which means that its truth cannot be investigated one way or the other using the scientific method and empirical evidence. Therefore it is non-scientific and simply doesn't belong here, regardless of whether or not it is true.

You may choose to assert its truth value, but you cannot provide any experimental evidence to support that assertion. There are also some unfalsifiable things which I believe are true, but neither of us get to discuss them here on PF.

 

[rocket123456]

So what? I have never made a claim that it is false.

It is unfalsifiable, which means that its truth cannot be investigated one way or the other using the scientific method and empirical evidence.

Please don't spam mr Spam you have made your point very clear.

<I don't know> if it's the case that it's unfalsifiable. Many physicists are very persuaded by the block-universe thesis.

I suppose they have some investigation behind these strong counter-intuitive beliefs.

One example of possible falsification would be a time travel in the future and see if some of the paradoxes are avioided as the block-universe predicts. Many of Einsteins "theorys"(he really took them from another dude but explained them better) predictions were at first not possible to test.

 

[Dale]

Please don't spam mr Spam you have made your point very clear.

<I don't know> if it's the case that it's unfalsifiable.

How often I repeat it is entirely up to you. If you are tired of seeing me repeat my falsifiability point then stop using a non-falsifiable definition.

If you believe that it is falsifiable then simply stop avoiding my repeated challenge and post the experiment which, in principle, could be performed and the outcome of said experiment which would disprove it.

 

[rocket123456]

How often I repeat it is entirely up to you. If you are tired of seeing me repeat my falsifiability point then stop using a non-falsifiable definition.

If you believe that it is falsifiable then simply stop avoiding my repeated challenge and post the experiment which, in principle, could be performed and the outcome of said experiment which would disprove it.

I already said time travel and the lack of free will to create paradoxes.

 

[Dale]

I already said time travel and the lack of free will to create paradoxes.

That isn't an experiment. That is a science fiction screenplay theme.

 

[audioloop]

Determinism should be viewed as religious fatalism.

your position.


-------

indeed falsifiable

He is using some philosophical definition

Popper (philosopher). falsifiability as the name of this criterion.
Popper, K. R. (1994). "Zwei Bedeutungen von Falsifizierbarkeit [Two meanings of falsifiability]". In Seiffert, H.; Radnitzky, G..

 

[joseph0887]

Thankyou for your answers, and interesting discussion.
I guess I would like science to have some philosophical input. Quantum Interpretations seem a rich ground, though I understand why many adopt the shut up and do the maths approach.