Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Time Symmetric Interpretation

  1. Jul 5, 2011 #1
    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/ap...ticle_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 travelling 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.
     
  2. jcsd
  3. Jul 5, 2011 #2

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    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.
     
  4. Jul 5, 2011 #3

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    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.
     
  5. Jul 5, 2011 #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 knowledgable than me in this subject.
     
  6. Jul 5, 2011 #5

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    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.
     
  7. Jul 5, 2011 #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
     
  8. Jul 5, 2011 #7

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    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.
     
  9. Jul 5, 2011 #8
    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.
     
  10. Jul 6, 2011 #9

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    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.
     
  11. Jul 6, 2011 #10

    DevilsAvocado

    User Avatar
    Gold Member

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

    (:rofl:)
     
    Last edited by a moderator: May 5, 2017
  12. Jul 6, 2011 #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.

    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.
     
  13. Jul 6, 2011 #12

    DevilsAvocado

    User Avatar
    Gold Member

    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:
     
  14. Jul 6, 2011 #13

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    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.
     
  15. Jul 6, 2011 #14

    Fredrik

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    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.
     
  16. Jul 6, 2011 #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.
     
  17. Jul 6, 2011 #16

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    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:
     
  18. Jul 6, 2011 #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 theres 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?
     
  19. Jul 6, 2011 #18

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    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...
     
  20. Jul 6, 2011 #19

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    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:
     
  21. Jul 6, 2011 #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
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook