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How to traverse infinity

  1. Jul 3, 2014 #1
    If our universe has a history of infinity of cause-effects/time, how could it ever traverse that infinity to reach 'now'.

    I mean to say, even if our universe started with a big bang, there must have been some cause for it, then a cause for the cause that caused big bang and so on ad infinitum.

    How can this infinity be ever traversed to reach the present time?
     
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  3. Jul 3, 2014 #2

    phinds

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    Why do you think it does?

    That becomes "turtles all the way down" and is not science but philosophy

    Doesn't seem likely does it?
     
  4. Jul 3, 2014 #3

    I think it does because there seems no other logical conclusion. In fact this seems inevitable.
     
  5. Jul 3, 2014 #4

    micromass

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    The more you study science, the more you will see that nature has a habit of not following our logic. We always need to adapt our logic and way of thinking in order to understand nature. Many people in the past have had ideas on how our world should behave logically, most of them were wrong.

    I am not convinced that everything in our world has a cause. Many occurences in QM seem to happen completely randomly without any cause. Maybe there is an underlying determinism that can give you this cause, or maybe our philosophy that "every effect must have a cause" is just wrong.
     
  6. Jul 3, 2014 #5
    Ah! I feel nervous...

    Even if the philosophy of 'cause and effect' is wrong ( i cant somehow believe it to be so), time is almost certainly eternal.

    If one says time started with big bang, there must have been some 'ttiimmee' before that 'caused' big bang.

    Even if big bang was not caused, it must have taken some 'ttiimmee' to come into existence, even if this ttiimmee is infinitely small. It hints time was already there.

    So, how we traversed this infinite time to reach the present?
     
  7. Jul 3, 2014 #6

    micromass

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    Why do you say this? How do you know there was anything before the big bang. Just saying "it is logic" or "it is my intuition" or "I believe it to be so" doesn't cut it. Logic, intuition and beliefs were wrong before.
     
  8. Jul 3, 2014 #7
    Let me present the other scenario.....

    Big bang happened from a primordial ball extremely small in size. Time may have existed, since there must have been some motion in that ball that led to explosion.

    if we negate this, big bang then becomes the case of 'something from absolute nothing'. This seems utterly implausible.

    The QM thing you talked about has quantum fluctuations to begin with. Particles don't spring out of absolute nothing.

    This hints the presence of 'something' before bigbang and this in turn hints at time via the question.....How and when this something came about?
     
  9. Jul 3, 2014 #8

    micromass

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    You are severely misunderstanding the big bang. The big bang theory never says that something came from nothing. The big bang theory never says that the universe was somehow infinitely dense and then expanded. All it says is that there is a hypothetical point in time where it seems that the universe was infinitely dense. However, the big bang theory only starts working until ##10^{-43}## seconds after the hypothetical point in time. It makes no statements what-so-ever about what happened before ##10^{-43}## seconds after the hypothetical point. Nobody knows. There are a lot of theories, but nobody really knows. So nobody is saying that something came from nothing.

    That was not really what I was refering to.
     
  10. Jul 4, 2014 #9

    Chalnoth

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    In physics, the idea of cause-effect relationships just doesn't describe reality very well. In fact, it isn't even clear that the traversal of time is anything but an illusion.

    For example, in General Relativity, space-time is described as a single entity (called a manifold). This entity doesn't traverse time, and neither does anything within it. It just exists across all time and space. The passage of time arises as an emergent property of certain specific configurations of the manifold. Specifically, if you have a low-entropy state, then you will see events that look like the passage of time in both directions away from that low-entropy state.
     
  11. Jul 4, 2014 #10

    Chronos

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    To expand on Chalnoth's explanation, a photon has no sense of time. It can traverse any distance you care to imagine in no time whatsoever, with respect to its reference frame.
     
  12. Jul 4, 2014 #11

    Thanks for correcting me.

    So, we dont know.

    But still, there seem to be two options only. Either there was sth before big bang or there was nothing. In both cases we cant avoid infinity.

    1. If there was something, how it came about. If we find another something from which the first sth came about, the next question is 'how the second sth came about' and so on....

    2. If there was absolutely nothing before bigbang, we can ask, 'what is the mechanism for this.' If we find some mechanism, we can say 'what is the mechanism for the mechanism that brings sth from nothing and so on.....

    So, how to traverse this infinity?




    Moreover, Do you think questions will ever end? Will a state come when there will be nothing else to know? I don't think so.

    Isnt this an infinity in itself?
     
  13. Jul 4, 2014 #12

    Chalnoth

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    It's a bad question. It's not a question that makes sense in terms of physics.
     
  14. Jul 4, 2014 #13

    I dont understand this. When i talked about time being an illusion, my thread was closed!!!
     
  15. Jul 4, 2014 #14

    Still, it seems a valid question.
     
  16. Jul 4, 2014 #15

    Chalnoth

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    Whether or not time is an "illusion" is an active debate within physics. But I don't think there's any getting away from the idea that the passage of time is an emergent property.
     
  17. Jul 4, 2014 #16

    phinds

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    and either one of them as you expressed it is turtles all the way down and we just don't know. At present, this is as I said earlier speculative philosophy, not physics.
     
    Last edited: Jul 4, 2014
  18. Jul 4, 2014 #17

    Even if we know the answer in future, can we escape this 'turtles all the way down' thing.

    Please try to explain.
     
  19. Jul 4, 2014 #18
    Enquire always, here are some thoughts I have had regarding your question. I will describe them in purely naturalistic terms because of their implications for cosmology if true. I think it may be possible to have causality without time. For instance, the flow of sound logic on a printed page is a sort of cause and effect, but all of the thoughts exist all at once on the page. How could time come to exist in a timeless realm of cause and effect? One possibility is the arrow of thermodynamics, as already mentioned. Another is that time may be apparent only to minds riding and observing the advancing edge of causality, like a man on a raft riding the front of a flow of water released from a dam. Whatever time is, both it and causality seem to have a "now," an edge, that flows in one direction. That seems to mean that both are like a finite ray with an advancing edge that we ride, with the potential to continue forever but requiring a beginning. This would mean that neither of them is an infinite continuum. If they were, as you mentioned, we could never have arrived at the present time or state of causality. It would also mean that there must be a beginning to both time and causality. The first cause by definition must be either uncaused or self-causing. If there was a first cause, that is something, not nothing. So you would not get everything from absolutely nothing, but rather from a causative something.
     
    Last edited: Jul 4, 2014
  20. Jul 4, 2014 #19
    ... No-maybe, but we sure have a something to make intuitive sense to it. We derived at infinities whether we like it or not. Integral part of math; To string people it is treated as (1/12)-Riemann Zeta function lims→1ζ(s)=−1/12 while to LQC people-'bounce' where* the turtle is somehow slowly turning all the way up at some point flipped back again in an endless cycle (analogy).. Anyway, I couldn't find any mechanism that deals well with divergent functions than bounce.
     
  21. Jul 4, 2014 #20

    phinds

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    I have no idea.
     
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