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Big bang questions?

  1. Oct 24, 2012 #1
    How long did the big bang last (initially)? How far did everything travel in that time? I was under the impression that it all happened in a fraction of a second and some things went many light years. If I'm right, how is that possible? (Traveling faster than the speed of light). If I'm wrong, what actually happened? Thanks
  2. jcsd
  3. Oct 25, 2012 #2


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    Well, the early universe doubled in size about 80 times before settling down in the boring old radiation/matter/expansion version we now observe. And, all that happened in only a few ticks on the planck clock
  4. Oct 25, 2012 #3


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    And when Chronos says "doubled in size about 80 times..." he means that space itself expanded by this amount. Imagine a rubber sheet that starts stretching at the time of the big bang and continues to stretch today -- this is expansion. Light still travels at c during expansion.
  5. Oct 25, 2012 #4
    I think its right to say the "big bang" refers to a theory that the universe expanded from a very hot dense state. That expansion is estimated to have began about 13.7 bio years ago. But of course is still going now, it has never stopped since that period.

    I think what is being discussed here is the inflationary period. This is the theory that the unvierse went through a period of very rapid expansion. Nobody knows how long it lasted, but if my memory serves me correctly (feel free to correct me if I have it wrong) but somehting like a doubling every 10^-37 seconds and at leats something like 60 doubling times. This number is estimated from the amount of doubling which are reuiqred to solve some difficult problems found in the standartd (without inflation ) big bang comsology.
    Read here:

    To answer the question how could space have moved faster than light? Reltavity forbids obejcts to pass each other through space faster than light. But it has no restriction on how fast sapce can expand.
    Did inflation happen ? there is good evidecen that it did but we are still waitiing for one more key test, read here:

    I think until that test (read the article) is done there is still room for doubt, but at the moment I think most astronomers would put their money on inflation being right as it has passed many tests so far.
    Last edited by a moderator: May 6, 2017
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