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Big Bang, Gravity Split

  1. Jun 15, 2009 #1
    At the point of the big bang, when did gravity split off from the other forces? How many seconds in (i.e. 10^-30 seconds or something like that)? I've been curious as to how the forces split; I was hoping for a specific number here, but I never found one.

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  3. Jun 16, 2009 #2


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    It is believed gravity split from the primordial 'superforce' almost simultaneously with the big bang. See Neil Tyson's discussion here
    http://www.haydenplanetarium.org/tyson/category/subjects/bigbang [Broken]
    Last edited by a moderator: May 4, 2017
  4. Jun 16, 2009 #3


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    There is no known answer to the question, because as far as General Relativity is concerned, gravity is not a force, and operates in a fundamentally different way to the 'other' forces.

    We have two theories, quantum mechanics and associated field theories work very well at describing the electromagnetic, weakd and stronge forces, but only if you ignore gravity. This is usually okay, since if you are talking about the interaction of some particles, their mutual gravity is so small as to be ignorable. On the other hand, when gravity is important, such as in the orbits of planets, galaxies etc etc, all the other forces are miniscule, so you can just worry about gravity and use General Relativity instead of quantum mechanics.

    The problem arises when gravity and other forces are of comparable strength, this require large densities (to make gravity strong) so is a problem for black holes and the early Universe. In theses regimes, the only answer is that we don't know. Coming up with a suitable single theory that looks like GR in the places were we now use GR, and QM in places we now use QM but that also doesn't break down for black holes and the early universe is one of the holy grails of modern physics, and there are no good indications that we are close to success at this stage.
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