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Existance of time before big bang

  1. Aug 20, 2011 #1
    dear all,

    i want to know that is time exist before big bang , if yes then what is actual origin of time and if no then why expansion(explosion) of universe happen through big bang and why it occur and why explosion took place..........it can be separated like bacterias.....???????????
     
  2. jcsd
  3. Aug 20, 2011 #2

    mathman

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    Any attempt to describe "before" is pure speculation.
     
  4. Aug 20, 2011 #3

    marcus

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    Why? We have models of what the earth was like "before" life existed on it.
    Any scientific reconstruction of the past is based on testable models.

    Now we have various models that go back in time before the start of expansion. At least one of them is predictive. Now the focus should be on testing the model or models that do go back in time.
     
  5. Aug 20, 2011 #4

    Chronos

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    Time before 'time' implies this universe originated in some sort of pre-existing background. I am uneasy with that idea, but, all for testing it.
     
  6. Aug 21, 2011 #5
    Last edited: Aug 21, 2011
  7. Sep 4, 2011 #6
    Like the x,y,z lines in 3 dimensional space has its origin in the middle, do the same for the big bang and the time line. put the big bang in the middle (not the far left) and have time leaving it in two directions. The big bang created a mass universe (us) and an antimass universe traveling in opposite directions in time and yet filling the same space.
     
  8. Sep 4, 2011 #7

    Ryan_m_b

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    This makes no sense, time cannot go in two directions and there is currently no contemporary theory that can explain the conditions at t=0, nor explain what before t=0 was like (and if that question even makes sense). As for an "antimatter universe" I have not heard that said by anyone except the SF author Iain M Banks...
     
  9. Sep 12, 2011 #8
    Why do you say time can't move in two directions? All physical equations that utilize time as a variable function just as effectively if time is negated.

    Anyway, "time" isn't a universal constant; far from it. Time does what the local and "global" energy state of the universe tells it to do. And we only have one way of experiencing time, whose to say we have got it right?
     
  10. Sep 12, 2011 #9

    Ryan_m_b

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    Because everything travels forward into the future, never in the past
    http://en.wikipedia.org/wiki/Arrow_of_time

    More than that time before the big bang in the manner described by Eric would not suggest time moving in the opposite direction, this makes no sense and has absolutely no evidence for it.
     
  11. Sep 12, 2011 #10
    Well, giving us a natural and unavoidable bias is the fact that it is only possible for us to observe time in the forward direction (since our brains function via categorization).

    In fact, though, there is a lot of mathematical evidence supporting the conclusion that the "arrow of time" is, in fact, an illusion. That all states and "times" exist simultaneously, so to speak, and that it is only our place in the system and the way our brains process the surroundings that create this sense of progressing time.

    Am I saying that time doesn't exist? Practically, no. In a practical sense, time exists insofar as I experience time moving forward. Possibly, though? Heck, maybe. We have shown that relative time can be slowed, even theoretically stopped. We don't really have a very firm grasp on things at the moment, much as we would like to think we do.

    I mean shoot, we don't even have a physical theory that can adequately explain everything that goes on in this funky universe!
     
  12. Sep 12, 2011 #11

    Ryan_m_b

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    You cannot theoretically stop time. The arrow of time is the observation that cause and effect occurs in one direction. If you have evidence that cause and effect can be reversed then you'd be in line for a serious prize.

    Also the fact that we do not have a comprehensive understanding of everything does not mean we cannot make comprehensive statements about anything. I would advise you to read the forum rules about overly speculative posts.
     
  13. Sep 12, 2011 #12
    If our observation of time can only occur in one direction, then there would be no way to falsify the observation that effect follows cause. There are many arguments, and indeed physics doesn't care either way, that say neither is "after" the other. Some even go as far as to say the effect implies, or even brings about, the cause.

    Physics doesn't care if you use a positive or negative time. What caused the big bang, if there was no time prior to the event? Not that I really expect you to answer that, I just mean that we ought not take causality as necessarily valid or locked in its direction (i.e cause-->effect) when we cannot falsify the claim. Again, pragmatically it makes sense to accept it, but we are within the system, and when we start talking about things that transcend or are outside of this system, then we have to consider all of our assumptions as suspect.

    Your point about our ability to make comprehensive statements is valid enough, I simply meant that, given our limited understanding of the way things work in this universe, I don't think we are in a place to talk so declaritively about the arrow of time, especially since it has recently (relatively) been shown to be a much trickier subject than we had originally thought.

    We don't really understand the way the universe works. It isn't speculation, it's just the way it is. In just the last century there have been multiple paradigm shifts that have completely changed the way we think about the world we live in. Time went from a constant to a relativistic variable, atoms went from being the base of existence to being the next step up from the wild, mostly ill-understood world of the quantum. I personally have never seen any arguments for time "running backwards at the big bang with antimatter", and I hesitate to agree, but I do question the declaration that time necessarily runs only in one direction.
     
  14. Sep 12, 2011 #13

    Ryan_m_b

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    Who said there was no time? I certainly didn't I was objecting to the claim that there was some bizzare mirror image universe before hand because there is no evidence for such a thing.
    How can something be outside of time? Again I think you are straying into very speculative territory here.
    The fact that things have been revealed in the past has no bearing on what will be revealed (if at all) in the future. When we say "time runs in one direction" it is because it has never been observed to do so. You do not get regions of the universe where time runs backwards.
     
  15. Sep 12, 2011 #14
    I may be out of my depth here, but I believe he is referring to the idea that antimatter travelling backwards in time would be observed as normal matter moving forwards in time. And so, in theory at least, since we observe normal matter and antimatter in our universe, IF antimatter was just matter moving backwards through time, then the big bang may have pushed bits of matter in 2 directions (but obviously not to before the big bang happened), just so that we would be able to observe both directions but not necessarily tell them apart, as it all just appears to go forwards.

    So in other words, I can maybe see what he's saying, but I can't really explain it very well. Even so, I'm not sure that he can just make the assertion that that's what happened. Sounds very speculative to me.
     
  16. Sep 13, 2011 #15

    Ryan_m_b

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    I got what he was trying to say it just makes little sense and isn't supported by any evidence aside from Iain M Bank's Culture novels.
     
  17. Sep 13, 2011 #16

    Chronos

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    The laws of thermodynamics may shed some light on the issue.
     
  18. Sep 13, 2011 #17
    Where comes time prior to space-time?

    Given that we have only directly studied a fraction of our star system, and that we have very little knowledge of what is going on in our own galaxy, and that there are billions of galaxies in places so distant we can't even imagine them...don't you think you are overstepping the appropriate certainty here? I mean, I am not arguing that there are, as you say, regions where time runs backwards, or anything like that, but given our limited understanding, and our limited scope, there very well could be regions where time acts very differently than it does here. This isn't speculation, this is skepticism. What happens to time in black holes? Inside stars? Supernovae?

    All I'm saying is that time is a funky thing that, while we thought we had a tight grasp on it, it turns out we didn't. What meaning does time really have for the quantum world? Where the same thing can be many places at once or "go" from one end of the universe to the other in zero time?
     
    Last edited: Sep 13, 2011
  19. Sep 13, 2011 #18

    Ryan_m_b

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    I don't understand your question. What makes you think there can be something outside of space or time?
     
  20. Sep 13, 2011 #19
    As far as this point goes, I think we are arguing the same thing. You agree that there is no meaning in saying anything about "before" the big bang, correct?

    **Also, I added some stuff to the last post, just in case you didn't see it.
     
  21. Sep 13, 2011 #20

    Ryan_m_b

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    Yes I am saying that. I am also objecting to the way that when I say something you say "well we haven't explored the whole universe so you can't say that" when in fact I can. All evidence points to the conclusion, whilst there may be unknown evidence there is no point taking it into account because it is an unknown. All statements in science are based on current evidence until new evidence comes along. Nothing is absolute, only based on what we know now.
     
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