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Is time reversal logically consistent?

  1. Sep 25, 2011 #1
    If you have three observers A, B, and C, if A is running backwards in time according to B, and B is running backwards in time according to C, does this mean that A must in run in the same direction in time as C, according to C (and/or vice versa)? Or does special relativity allow A to run backward in time according to C (and/or vice versa)?
     
  2. jcsd
  3. Sep 25, 2011 #2

    Dale

    Staff: Mentor

    Time never runs backwards. I don't know where you got that from.
     
  4. Sep 25, 2011 #3
    https://www.physicsforums.com/search.php?searchid=2878677 [Broken]
     
    Last edited by a moderator: May 5, 2017
  5. Sep 25, 2011 #4

    Dale

    Staff: Mentor

    Which of those do you believe is related to your question in any substantive way? I.e. Which of those supports your premise that there exists some observer B for whom A's clock is running backwards?
     
  6. Sep 25, 2011 #5
    Ok, I just changed the post after you replied. Here's the new link:

    https://www.physicsforums.com/search.php?searchid=2878677 [Broken]
     
    Last edited by a moderator: May 5, 2017
  7. Sep 25, 2011 #6
    It looks like the search results aren't specific enough. So I will simply ask you a few simple questions that rely on less unstated context.

    Would, according to SR, time reverse for particles traveling faster than light? Then, if faster than light particles were observed, would observers sharing their frame of reference be consistent in the manner suggested at the beginning of the OP?

    Or not?

     
  8. Sep 25, 2011 #7
    Also, note in another thread, I had received the following response:

    https://www.physicsforums.com/newreply.php?do=newreply&p=3521551 [Broken]

    It appears that he is suggesting that there can be such a thing as a super-luminal Lorentz boost. This has actually been suggested in scholarly papers:

    http://scholar.google.com/scholar?hl=en&q="superluminal+lorentz"

    But additionally, he seems to imply that whether an object appears to be super-luminal or not can depend on the frame of reference, though this was off a tangent where my main focus was about an observer in the laboratory frame of the recent CERN neutrino experiment.
     
    Last edited by a moderator: May 5, 2017
  9. Sep 25, 2011 #8

    Dale

    Staff: Mentor

    Special relativity does not allow any reference frame's time to run backwards according to any other reference frame. Special relativity also does not allow any frame to travel faster than light wrt any other frame.

    The symmetry group of SR is the restricted Lorentz group.
     
  10. Sep 25, 2011 #9
    A: Time reversal is not logically consistent with SR.

    Emphasis: "restricted Lorentz group."

    Got it. Thank you.
     
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