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I Does the 1 Second after the Big Bang = 1 second now?

  1. Jun 22, 2016 #1
    When I read that conditions were such and such 1 to .05 seconds after the big bang, is that duration somehow longer than 1/2 second is now (maybe because of the difference in density or like the twin paradox?)?
    Last edited: Jun 22, 2016
  2. jcsd
  3. Jun 22, 2016 #2
    Do you mean one second after the Big Bang? There is no before the Big Bang.
  4. Jun 22, 2016 #3
    sorry S/H/B "After"
  5. Jun 22, 2016 #4


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    I fixed your thread title for you. :smile:
  6. Jun 22, 2016 #5
    The duration of 1/2 second right after the big bang is the same as the duration of 1/2 second now.
  7. Jun 22, 2016 #6
    Cosmic rays decay at a different rate ( I think) but, from your answer, that is a different type of situation?
  8. Jun 22, 2016 #7


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    I'm not sure your question is well posed.

    It is true that two clocks that are synchronised, moved apart, and brought together again may no longer be synchronised. But how would you bring a clock from one second after the Big Bang together with one now in order to compare them? There's no meaningful way to do that, so I'm afraid that there's no physical way to ask your question, let alone answer it.
  9. Jun 23, 2016 #8
    I think I read time seems to almost stop in a black hole. So I was wondering if the same was true for the big bang and if when it is said something happens from .5 seconds to 1 second after the big bang what frame of reference that is in.
  10. Jun 23, 2016 #9


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    Either you misunderstood what you read or it's wrong. Unless you tell us what you read where, we have no way of knowing which it is.
  11. Jun 23, 2016 #10


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    What makes you think that?

    It is in the standard coordinates used in cosmology. Time in these coordinates is the same as time elapsed on the clocks of "comoving" observers, i.e., observers who see the universe as homogeneous and isotropic.
  12. Jun 24, 2016 #11
    Pretty sure he's referring to time dilation from general relativity.

    The fault in logic here is that from the perspective out an outside observer, time moves way slower close to a black hole. From the frame of reference of something already in the hole, time moves normally. You can't use the same logic when applying to the universe as a whole because we're in the same reference frame.
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