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How can time have a beginning?

  1. Dec 18, 2009 #1
    The big bang states that time/space was a product of the expansion of the initial singularity of our universe. Now in order for our universe to initiate the big bang, causality must be invoked to start inflation, hence started time itself. But, how can causality be invoked if there is no time to begin with?

    Also, time cannot be infinite because it would need an infinite regressions of time, hence we would never reach this point in time ourselves. Is there a solution to this paradox? Is there such thing as a flow of time, or is it just snapshots being created over and over again?
     
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  3. Dec 18, 2009 #2

    PhanthomJay

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    From my limited knowledge of the Cosmos, nothing can ever be known about our universe within the first 10^-43 seconds (Planck Time) after the Big Bang. Kind of sad, isn't it? :cry:This question should be posted under the cosmology section, where there are experts there who can give a much better answer.
     
  4. Dec 19, 2009 #3

    DaveC426913

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    Sound like you want to read up on Zeno's Arrow Paradox or Achilles and the Tortoise.
     
  5. Dec 19, 2009 #4
    First answer, no. Second answer, yes.

    In Thermodynamics time relates to temperature measurements and the definition of entropy. If observations show that the Universe tends to increase entropy during every process (at each instant of time) then we infer a lower entropy state in the past, ending up with a singularity or Big Bang. Also the Universe appears to be expanding so that gets factored in.

    However even in the definition of thermodynamic variables there is this paradox of continuous versus discrete time. If a process is non-quasistatic, it has unknown states over time, and we can only measure properties of the system at end states, known as equilibrium states. Therefore we have only snapshot information about the process.

    What we do know (or assume to know) is that a system cannot change states in zero time, or the process would require infinite power. Therefore if even a finite change in energy cannot occur in zero time, how can we possibly define a "creation event" which would require infintite power? This is why I regard much of the speculative science as a modern form of mythology. It is a mythology consistent with many empirical observations but it has no empirical claim to validity. Perhaps humans cannot imagine a creation event and therefore it is at least reasonable to imagine a God or all powerful process in the Universe.

    Coherence however is a powerful tool in science. Most scientists attempt to find a coherent model to explain experimental results, and some succeed spectacularly. This does not remove paradox from the foundations of knowledge. Another fruitful area is fuzzy logic and neural networks which reveal that paradox or fuzzy sets are inherent in the processing of information. Paradox is central to how we think according to these studies.
     
  6. Dec 19, 2009 #5

    arildno

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    Think of "The Universe&Its History" as a cone or paraboloid.

    The natural laws define its properties at ALL points.

    Then, the "apex" is the beginning (fully accounted for by the natural laws), the distance from the apex as "time", whereas the local diameter there as a measure of the amount of space at that moment.


    This is an image that shows how a point that in some sense is very "special" (i.e, the apex), still can be regarded as included within over-arching laws that also regulate more mundane spacetime-events.
     
  7. Dec 19, 2009 #6
    I think its pretty safe to say nobody has an answer to this question. Its really not even accurate to say that the universe began as a singularity. Before 10^-36 seconds after the big bang no current theories of physics apply.
     
  8. Dec 19, 2009 #7
    I like the cone analogy in terms of the Big Bang as coherent with much that we know. But I would put the "laws of nature" in quotes. I prefer to think of these concepts as compelling ideas which work for the time-being. They are laws of nature as we know it now, but nature may have many other properties of which we are entirely ignorant.

    Does time stop for a photon in a beam of light? Or if a clock is taken down to absolute zero temperature, could it still keep time? If we measure time as observed frequency (counting of tic-toc oscillation) then beyond frequency there is no time ...
     
  9. Dec 20, 2009 #8

    arildno

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    The laws of nature (or the laws governing the evolution of the laws of nature) are the same, irrespective of whether the ancient Greeks or Actecs knew of them or not.

    Same holds for us, of course, with the extremely important difference that our manipulative and predictive abilities concerning nature are far greater now than ever before..
     
  10. Dec 20, 2009 #9
    What proof does one have that a law of physics as we know it is valid at every point in space and time? Or is this an axiom? Since humans don't exist at every point in space and time, I would infer that we do not and cannot know the "laws" of nature in domains where reasoning and observation don't even exist. We only know our relationship to creation as it is and everything else is mere speculation ... (mythology or story-telling).
     
  11. Dec 20, 2009 #10
    I entirely agree with SystemTheory. There is simply no way of proving that the "Natural Laws" we have now are perfectly stable relative to all points in time and space. If you think about it, all the evidence we have about the universe has been gathered from only one minuscule point in that vast space and time of our universe. Also, the tools with which we observe the universe are perhaps incapable of grasping all the aspects. I guess the only thing we can say is that there is at least seems to be some order in the world we currently perceive. That doesn't mean order is permanent. (sorry, got a little off the topic.) But I think in general their is no way around this paradox. Perhaps our human brain is incapable of computing something so enigmatic to our system of logic. The way i like to get out of the paradox is not to think of time as a linear event but instead cyclic. (not sure if i actually believe it, but it would be nice).
     
  12. Dec 20, 2009 #11

    DaveC426913

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    It is an axiom. We assume that our location in the universe is not special or privileged.

    It can't be proven, but it can be assumed unless there's a reason to think otherwise.

    Furthermore, absolutely nothing constructive can come from speculating without evidence that the laws are different elsewhere (all other things being equal). Since it can't be proven or disproven, any hypotheses based on it or utterly baseless.
     
  13. Dec 20, 2009 #12
    I think it can really go either way.There is no way to say that our laws for the universe apply everywhere and at every time, because we simply haven't been there. At the same time,as DaveC4 said, there is no evidence that tells us that we should believe otherwise if our current scientific data is congruent with these laws.
    But these points are mute.
    Really what this is about is ideology. It just seems a little dangerous to me to start believing that humans have found some kind of "ultimate truth" linking EVERYTHING. You start going down this road, and science suddenly becomes religion. It's just a little too presumptuous for my liking, also rather ego-manical, to state that these laws are unequivocally true, but not only that, projecting them onto places we have never actually been to do any kind of true testing.
    Personally, i kinda like the idea that the universe does not have to conform to the laws that we try to encapsulate it in. That it is mysterious, in flex, and can break the laws we set for it. As it happens, this allows us the chance to test ourselves and find new ways to looking at things. Is that not the mechanism for which science has progressed up till now? By allowing room for endless possibility? I like to leave room for that one odd place in the universe that an apple does not fall, but perhaps stays floating in the air.
     
  14. Dec 20, 2009 #13

    DaveC426913

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    Or possibly moot? :wink:
     
  15. Dec 20, 2009 #14
    hi there was no big bang in the first place. [why] because our universe is flat dont take my word ask any astromomer worth his salt. so my question how can you have a flat explosion. nun of them can answer that question. and i have asked many they just shrug there shoulders and walk of. you cant have 1 law for an explosion and another for the big bang. so no big bang that means no black holes.i though we had learned seems like NO.
     
  16. Dec 20, 2009 #15

    DaveC426913

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    They shrug their shoulders and walk off because they would have a long way to go to explain it to you. For starters, the Big Bang was not an explosion. The rest of your question sort of falls apart after that. A little bit of reading on the subject may clear up some of your confusion.
     
  17. Dec 20, 2009 #16
    if the big bang wasn't an explosion what was it
     
  18. Dec 20, 2009 #17

    DaveC426913

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    That wasn't nice Dave! Integral

    The Big Bang was a geometrically rapid inflation, driven by negative pressure vacuum energy.

    An explosion is fundamentally different in that, among other things, it is a pressure at the centre that pushes outward, and once that's completed the outward moving material moves on a ballistic path.
     
    Last edited by a moderator: Dec 21, 2009
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