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Change in a singularity!

  1. Mar 12, 2010 #1
    If time and space did not exist before the big bang then how could the change from a singularity to the big bang occur? Since change needs time as a prerequisite.
     
  2. jcsd
  3. Mar 12, 2010 #2
    That is a question to which there is no answer yet, and may never be. You're basically asking what space and time are, and while plenty of models and theories OF spacetime exist, "what came before" is really the realm of philosophy and religion barring major breakthroughs in an understanding of quantum gravity, and probably a lot more.

    That said, this doesn't stop theories to explain what you're saying from being proposed. There is something called Brane Cosmology (purely theoretical) as part of String/M-Theory which you might enjoy a bit of reading into. In that formulation, we're confined to dimensional "memBranes" in a multiverse of membranes. Fluctuations lead to sporadic collisions between branes, and the at that contact point what we call a universe is created. Truly, very elegant, totally untestable, and not substantially different from a wild guess.

    Physics can bring you CLOSE to those answers, and better yet, it gives you REAL guidance away from crackpottery et al. For answers to "why" or the ultimate, "from where" it's hard to imagine a scientific answer in our lifetimes, but we can dream.
     
  4. Mar 13, 2010 #3
    If Gravity effects time yet time is not required for gravity to exist (centre of black hole) then is not gravity just a shadow of another dimension that affects the physical world but is not a part of it? Can the effects of time affect the force of gravity? Are they reversible in the sense that one affects the other but not the other way round?

    Gravity is weird to say the least. :confused:
     
  5. Mar 13, 2010 #4

    Fredrik

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    The big bang theory is the claim that our universe can be described by a solution of Einstein's equation with an initial singularity. Such a solution describes a spacetime in which every event has a time coordinate t>0. There's no t=0, and the big bang isn't an event in spacetime, it's just a name for the mathematical limit t→0.

    In other words, the best theory of space and time that we have strongly suggests that it isn't possible to define the words "before the big bang" in a meaningful way. You may think that if there was a time t=0.5 seconds, there must have been a time a second before that, but that line of reasoning isn't valid. It's based on our intuition about the properties of time, but the fact that general relativity makes much better predictions about results of experiments than any theory that agrees with our intuition, proves that our intuition about time is wrong.

    The best theory of gravity is general relativity. It describes how the properties of spacetime are related to properties of the matter in spacetime. So the idea of gravity without time doesn't seem to make much sense.
     
  6. Mar 13, 2010 #5
    @Tanzanos:After all, it's not "space and time" it's "spacetime" from which gravity emerges. The two have not been seperated (and made better or equal predictions to SR/GR). Thinking of space without time in this context is actually MORE confusing rather than less. Space and Time are part of a fabric that (probably) inflated as a whole from the Big Bang on. If you want to think of a timeless universe... maybe you'd be thinking about the pre-BB state, but as Frederick said, no current theories describe that.
     
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