Time Symmetric Interpretation

In summary, the Time Symmetric Interpretation is rarely brought up in discussions due to its inability to restore determinism or realism. This interpretation suggests that the past and future may influence the present, but it does not provide a way to determine quantum outcomes. While some may find it appealing for its incorporation of c and quantum nonlocality, it still presents outcomes as random and unpredictable. Despite this, some still support it and believe it has more potential than other interpretations.
  • #1
Fyzix
173
2
Why are the Time Symmetric Interpretation rarely if ever brought up in discussions here?
It restores determinism and realism.

This article explains the jist of the interpretation and experimental evidence:

http://discovermagazine.com/2010/apr/01-back-from-the-future/article_view?searchterm=Tollaksen&b_start:int=0

People are willing to accept way more crazy ideas (randomness, collapse, many worlds etc.)
So why should subatomic particles traveling back and forth in time be so hard to swallow? After all we already know that eternalism is true.
Keep in mind that this is NOT the transactional interpretation, the transactional interpretation has indeterminism and collapse.
 
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  • #2
Fyzix said:
Why are the Time Symmetric Interpretation rarely if ever brought up in discussions here?
It restores determinism and realism.

This article explains the jist of the interpretation and experimental evidence:

http://discovermagazine.com/2010/apr/01-back-from-the-future/article_view?searchterm=Tollaksen&b_start:int=0

Time symmetric interpretations do NOT restore determinism or realism (as they are normally defined). Determinism requires the past alone to influence the future. And realism requires particles to have well defined observable values at all times, independent of the context of a measurement. Neither of these requirements are met by a TS interpretation.

However, they have the important advantage of providing something of a physical mechanism in which c is respected while still presenting quantum nonlocality as a natural outgrowth. So I tend to like them. But in the end, an interpretation is still an interpretation.
 
  • #3
Or to put it another way: Even if the hidden variables reside in the future, that alone does not provide a way to determine a quantum outcome. It is still random. No TS interpretation allows the outcome of a freely chosen measurement on an entangled pair to be predicted from a specified future state.
 
  • #4
No this is 100% deterministic :)
You should read the article...

Also what the hell does "predictability" have to do with ANYTHING?
Humans are not God, just because a human can't personally predict something doesn't mean that thing is random.

Do you really think that a throw of dice is really random just because you can't predict the outcome?

Just because we can't know how exactly the past & future will affect the present, doesn't mean they don't.

I can't believe I'm explaining this to someone who should be 500000 times more knowledgeable than me in this subject.
 
  • #5
Fyzix said:
No this is 100% deterministic :)
You should read the article...

Also what the hell does "predictability" have to do with ANYTHING?
Humans are not God, just because a human can't personally predict something doesn't mean that thing is random.

Do you really think that a throw of dice is really random just because you can't predict the outcome?

Just because we can't know how exactly the past & future will affect the present, doesn't mean they don't.

I can't believe I'm explaining this to someone who should be 500000 times more knowledgeable than me in this subject.

LOL. Sorry, just saying it is deterministic does not make it so. Even in a "highly respected" journal such as Discover. :biggrin:

Determinism means that if you knew all of the relevant variables, you could predict the outcome of any measurement with certainty. Well, what are the relevant variables? There is no TS theory that purports to answer this. All outcomes still appear random.
 
  • #6
First what is this idiotic statement "even in a highly respected journal like discovery", what is that even aimed at?
I told you to go back and read the article so you understood which time symmetric approach I was talking about and how they outline why it is deterministic.
It has nothing to do with the credentials of the magazine.

Secondly, yes it does indeed APPEAR random, but the interpretation explains that in reality it ISN'T, if you could know all the variables, just like the tired of dice roll argument, you could predict!.
So yes it APPEARS random, just like deBroglie Bohm, Gerard 't Hoofts interpretation and Many Worlds APPEARS to be random, while in reality they are deterministic.

So basically you are just repeating what the article is saying and think that somehow is an argument against the article.

Please stop ruining the thread, I intended it to be a discussion on the validity of TS and why it hasn't got more supporters, not a discussion about your subjective definition of randomness
 
  • #7
Fyzix said:
First what is this idiotic statement "even in a highly respected journal like discovery", what is that even aimed at?
I told you to go back and read the article so you understood which time symmetric approach I was talking about and how they outline why it is deterministic.
It has nothing to do with the credentials of the magazine.

Secondly, yes it does indeed APPEAR random, but the interpretation explains that in reality it ISN'T, if you could know all the variables, just like the tired of dice roll argument, you could predict!.
So yes it APPEARS random, just like deBroglie Bohm, Gerard 't Hoofts interpretation and Many Worlds APPEARS to be random, while in reality they are deterministic.

So basically you are just repeating what the article is saying and think that somehow is an argument against the article.

Please stop ruining the thread, I intended it to be a discussion on the validity of TS and why it hasn't got more supporters, not a discussion about your subjective definition of randomness

There is no reference in the article to a scholarly paper. But here is one from MY list of Time Symmetric Interpretation bookmarks (since there are a number of different approaches) that might be useful to discuss rather than to work against a pop science recap:

http://arxiv.org/abs/0706.1232

New Insights on Time-Symmetry in Quantum Mechanics (2007)
Yakir Aharonov, Jeff Tollaksen

And again, I defy you or anyone to show me where you can predict the outcome of any measurement by identifying and specifying the values of all theory relevant past and future variables. If you can do that, I will agree it is deterministic. Otherwise, it is simply a unsubstantiated claim.

P.S. Good luck. And you might want to discover the correct name of the magazine. Hint: there is no y at the end.
 
  • #8
Fyzix said:
... I intended it to be a discussion on the validity of TS
The time-symmetric assumption can only have a short-range validity. Surely OK for one edge between two vertices.
Soon, the macroscopic arrow of time must emerge.
The description of this frontier of validity and this emergence ? I do not know any, today.
 
  • #9
Hopefully Ruth's comment in the other thread the OP started will convince that TS interpretations are NOT deterministic. As mentioned there, the Born rule still applies.
 
  • #10
DrChinese said:
P.S. Good luck. And you might want to discover the correct name of the magazine. Hint: there is no y at the end.

He might have done yet another discovery... a completely NEW http://www.discoverymagazine.com/" [Broken]!

(:rofl:)
 
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  • #11
It's just hilarious to watch a grown man having to resort to ad hominem attacks "it's DISCOVER without the Y" just because his own logic doesn't hold up to the original argument.
Thank you sir, you made my day.

DrChinese said:
Hopefully Ruth's comment in the other thread the OP started will convince that TS interpretations are NOT deterministic. As mentioned there, the Born rule still applies.

Ruth's comment only applies to the transactional interpretation, which I state in the OP that I AM NOT talking about.TS is deterministic, end of discussion.
 
  • #12
Fyzix said:
... Thank you sir, you made my day.

You are most welcome sir, I’m glad you appreciated the 'silly little joke'.
"If you can't laugh at yourself, then who can you laugh at?" -- Tiger Woods

:wink:
 
  • #13
Fyzix said:
Ruth's comment only applies to the transactional interpretation, which I state in the OP that I AM NOT talking about.

TS is deterministic, end of discussion.

Time symmetric theories/interpretations follow the Born rule too. You probably don't realize that the ultimate purpose of time symmetry is to supply a mechanism which explains nonlocal correlations without needing an explicit nonlocal mechanism. These will not be any more deterministic than what it is supposed to replace.

Again, if you have some set of variables - for any theory - which allows measurement outcomes to be predicted with certainty... well, now would be a good time to present that to us.

Otherwise, this thread may as well be closed.
 
  • #14
Fyzix, I don't know what makes you think that replacing the Born rule with the ABL rule would make the theory deterministic. ABL can be derived from Born using Bayes' theorem.

Even if you had been right about the physics, your attitude is very inappropriate.
 
  • #15
How many of you actually read the article?
Sure they all follow born rule, that's what makes interpretations such as these viable vs other interpretations like MWI which can't make any sense of born rule and is thus falsified until they modify it.

Take dBB, it derives born rule, but it's also 100% deterministic!
It does not allow us to predict the trajectory of any particles, but we know that if dBB is true then the nature "behind the curtains" is deterministic but will forever appear random to us.

Same here: The past doesn't contain enough intel to predict the outcome in the present, they invoke the future here.
So yes to us in the present it will always appear random, but if this TSI is true, it is deterministic behind the curtains...As for my attitude, it's appropriate.
Did you read the replies of the other people?

This thread was opened to discuss TSI, not DrChinese personal fetish for indeterminism.
 
  • #16
Fyzix said:
Take dBB, it derives born rule, but it's also 100% deterministic!
It does not allow us to predict the trajectory of any particles, but we know that if dBB is true then the nature "behind the curtains" is deterministic but will forever appear random to us.

Same here: The past doesn't contain enough intel to predict the outcome in the present, they invoke the future here.
So yes to us in the present it will always appear random, but if this TSI is true, it is deterministic behind the curtains...

It may surprise you to learn that dBB DOES provide a deterministic answer to a measurement outcome when all input variables are known. And it identifies those elements, at least in principle. Ask Demystifier and he will explain this in a way I cannot.

But TS interpretations do not answer my challenge question, regardless of the amount of information supplied or "when" it is located.

You asked a question as to why TS is not more accepted. The answer is that you trade a nonlocal mechanism for a time symmetric one. Some folks like that deal, others don't. Realism and determinism are not part of the bargain. Although it might be possible to formulate a determinsitic version, as far as I know this has not happened so far. If it were, it would probably look a lot like dBB. And so would not offer us much in the way of useful advances.

Not that any of this will change your opinion. I suspect you are the kind of person who would put your hand in acid before you would admit you are wrong. But hey, I could be wrong about that. :biggrin:
 
  • #17
No, I tell you what.
Get Demystifier in here and make him say that dBB is random, there is NO determinism.
The particles do not have definite position or momentum in dBB.

If you make him say that, I'll admit that there's a chance I'm wrong that TS is also determinsitic, however this would also make every person who ever believed in dBB, MWI, TS wrong about their own interpretation.

Since you obviously know more than anyone in the entire universe combined you should just win a few nobel prizes right away, but you are too modest I guess?
 
  • #18
Fyzix said:
Since you obviously know more than anyone in the entire universe combined you should just win a few nobel prizes right away, but you are too modest I guess?

I'm glad you noticed! Modesty is one of my finest virtues.

And those *** Nobel folks. Don't get me started on them. They actually insist I DO SOMETHING IMPORTANT before I get my prize. Can you imagine...
 
  • #19
Fyzix said:
No, I tell you what.
Get Demystifier in here and make him say that dBB is random, there is NO determinism.
The particles do not have definite position or momentum in dBB.

You ARE funny, I guess I missed this side of you in our earlier discussion. Yes, I will be glad to make him say whatever you like. Especially things that are exactly opposite to his position. Do you want me to have him vote some particular way too? Or send you money?

:rofl: :rofl: :rofl:
 
  • #20
You don't even comprehend sarcasm...
And you have ruined a thread on a useful interpretation because of your obsession with randomness.
Why are you so hung up on randomness? Is it like those other idiots who NEED free will?

someone just delete this thread, DrChinese has made it completely worthless
 
  • #21
Fyzix said:
You don't even comprehend sarcasm...
And you have ruined a thread on a useful interpretation because of your obsession with randomness.
Why are you so hung up on randomness? Is it like those other idiots who NEED free will?

someone just delete this thread, DrChinese has made it completely worthless
No, you did. He wrote a good answer. You replied with insults and have been increasingly aggressive ever since.
 
  • #22
Fredrik said:
No, you did. He wrote a good answer. You replied with insults and have been increasingly aggressive ever since.

Nope, not at all :)
He kept INSISTING that TS would be just as random as copenhagenism, I told him to read the article, but he just refused and continued to say "it is random it is random it is random!".

If this TSI is random then dBB would be random too.
just because the variables aren't accesible to humans doesn't mean the universe in it self is random, man how arrogant can humans be!?
 
  • #23
Fyzix said:
... DrChinese has made it completely worthless

Sniff now my feeling are hurt... :cry:
 
  • #24
Fyzix said:
Nope, not at all :)
Good to see that you haven't lost your ability to deny the obvious.

Fyzix said:
He kept INSISTING that TS would be just as random as copenhagenism,
It is.

Fyzix said:
I told him to read the article, but he just refused and continued to say "it is random it is random it is random!".
Why would he read the article? Why would anyone? Some of us know a little about the topic already, and you didn't even bother to point out the parts of it that you think support your claim.
 
  • #25
Aharonov accepted that a particle’s past does not contain enough information to fully predict its fate, but he wondered, if the information is not in its past, where could it be? After all, something must regulate the particle’s behavior. His answer—which seems inspired and insane in equal measure—was that we cannot perceive the information that controls the particle’s present behavior because it does not yet exist.
“Nature is trying to tell us that there is a difference between two seemingly identical particles with different fates, but that difference can only be found in the future,” he says. If we’re willing to unshackle our minds from our preconceived view that time moves in only one direction, he argues, then it is entirely possible to set up a deterministic theory of quantum mechanics.


Satisfied?
 
  • #26
Fyzix said:
Aharonov accepted that a particle’s past does not contain enough information to fully predict its fate, but he wondered, if the information is not in its past, where could it be? After all, something must regulate the particle’s behavior. His answer—which seems inspired and insane in equal measure—was that we cannot perceive the information that controls the particle’s present behavior because it does not yet exist.
“Nature is trying to tell us that there is a difference between two seemingly identical particles with different fates, but that difference can only be found in the future,” he says. If we’re willing to unshackle our minds from our preconceived view that time moves in only one direction, he argues, then it is entirely possible to set up a deterministic theory of quantum mechanics.


Satisfied?

Doesn't even remotely support your assertion.
 
  • #27
Talking about not reading the article, I gave Fyzix a reference to a key work by the scientists mentioned in the Discover article. Obviously he has not read or understood it. From the paper "New Insights on Time-Symmetry in Quantum Mechanics" by Yakir Aharonov and Jeff Tollaksen:

http://arxiv.org/abs/0706.1232

"Contextuality (2.3) suggests that the measuring-device determines the
sets of possible micro-states [69, 70, 32]."

I.e. theirs is a contextual interpretation which an outcome is one of a set of possible states. They also mention that there is both a future component of a wave function and a past/present component which interact. Wave functions, of course, being closely related to the probability amplitudes for outcomes.

And nowhere do I see a claim that they have a way to predict outcomes based on future variables, nor that theirs is a realistic theory. All they are doing is working with an extra degree (half degree?) of freedom.

Thanks Fredrik.
 
  • #28
... I never stated, nor did they, that they would ever predict outcomes.
That is BEHIND THE CURTAIN. outside of reach for us!
 
  • #29
Fyzix said:
Why are you so hung up on randomness? Is it like those other idiots who NEED free will?

Why are you so hung up on determinism? Is it like those other maladroit’s who NEED someone to tell them what to do?

But, I suspect you did not check out the basic facts (again?), because there’s no automatic coupling between determinism & free will:

550px-DeterminismXFreeWill.jpg


Fyzix said:
just because the variables aren't accesible to humans doesn't mean the universe in it self is random, man how arrogant can humans be!?

True, a lot of puffy arrogance right there. Maybe we could get a slightly more fruitful environment if you would stop telling The Universe how to behave...

Wait, I just got an idea! Why don’t you call Professor Emeritus Walter Lewin and tell him to squeeze that slit juuuuuuuuuust a little bit more, so that we once and for all can get a look of these darned in inaccessible variables!


https://www.youtube.com/watch?v=KT7xJ0tjB4A

Or, we just have to accept the strikingly decisive physical fact – this the way the world works...
 
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  • #30
Fyzix said:
... I never stated, nor did they, that they would ever predict outcomes.
That is BEHIND THE CURTAIN. outside of reach for us!

I know they didn't. But you did, because you do not understand the difference between:

1. A theory in which we cannot predict an outcome because we can't know all the input parameters - sometimes referred to as stochastic. Throwing dice is considered a stochastic process as are stock market fluctuations. There are just too many parameters to learn precisely.

2. A theory in which even with all the input parameters known, no certain prediction is possible - sometimes referred to as non-deterministic. QM is such.

TSQM is of type 2. Suppose we have 4 variable parameters, 2 in the past and 2 in the future. Knowing any 3 should allow you to predict the 4th in a deterministic theory. You cannot do that with TSQM. And it matters not whether there are 4 or 4000 parameters, you still cannot predict the last one with certainty.

That is not to say that you could not attempt to develop a theory which is deterministic. But that has not been done yet for one which is time symmetric.
 
  • #31
If it helps, I also think that the Aharonov time-symmetric interpretation is purely probabilistic (and therefore not deterministic), while dBB interpretation is deterministic.
 
  • #32
Demystifier said:
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!

:smile:
 
  • #33
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.
 
  • #34
joseph0887 said:
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
 
  • #35
joseph0887 said:
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. :smile:
 
<h2>1. What is the Time Symmetric Interpretation?</h2><p>The Time Symmetric Interpretation is a theory in physics that suggests that the fundamental laws of nature are symmetric with respect to time. This means that the laws of physics are the same whether time is moving forward or backward.</p><h2>2. How does the Time Symmetric Interpretation differ from other theories of time?</h2><p>The Time Symmetric Interpretation differs from other theories of time, such as the block universe theory, by proposing that time is not an arrow that moves in one direction. Instead, it suggests that time is a two-way street, with events happening in both the past and future.</p><h2>3. What evidence supports the Time Symmetric Interpretation?</h2><p>There is currently no direct evidence that supports the Time Symmetric Interpretation. However, some physicists argue that certain phenomena, such as quantum entanglement and the behavior of particles at the quantum level, suggest that time may be symmetric.</p><h2>4. How does the Time Symmetric Interpretation relate to the concept of causality?</h2><p>The Time Symmetric Interpretation challenges the traditional concept of causality, which suggests that the cause must always precede the effect. In this interpretation, the cause and effect can occur simultaneously, and the direction of time does not determine the causality of events.</p><h2>5. What implications does the Time Symmetric Interpretation have for our understanding of the universe?</h2><p>The Time Symmetric Interpretation challenges our traditional understanding of time and the universe. It suggests that the past, present, and future are all equally real and that events can occur in any direction of time. This could have significant implications for our understanding of the origins and fate of the universe.</p>

1. What is the Time Symmetric Interpretation?

The Time Symmetric Interpretation is a theory in physics that suggests that the fundamental laws of nature are symmetric with respect to time. This means that the laws of physics are the same whether time is moving forward or backward.

2. How does the Time Symmetric Interpretation differ from other theories of time?

The Time Symmetric Interpretation differs from other theories of time, such as the block universe theory, by proposing that time is not an arrow that moves in one direction. Instead, it suggests that time is a two-way street, with events happening in both the past and future.

3. What evidence supports the Time Symmetric Interpretation?

There is currently no direct evidence that supports the Time Symmetric Interpretation. However, some physicists argue that certain phenomena, such as quantum entanglement and the behavior of particles at the quantum level, suggest that time may be symmetric.

4. How does the Time Symmetric Interpretation relate to the concept of causality?

The Time Symmetric Interpretation challenges the traditional concept of causality, which suggests that the cause must always precede the effect. In this interpretation, the cause and effect can occur simultaneously, and the direction of time does not determine the causality of events.

5. What implications does the Time Symmetric Interpretation have for our understanding of the universe?

The Time Symmetric Interpretation challenges our traditional understanding of time and the universe. It suggests that the past, present, and future are all equally real and that events can occur in any direction of time. This could have significant implications for our understanding of the origins and fate of the universe.

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