• Question: What is the main theory as to what happened before the big bang?

    Asked by 13marbles to Adam, Chris, Eleanor, Jessamyn, Sinead on 10 Nov 2013.
    • Photo: Adam Murphy

      Adam Murphy answered on 10 Nov 2013:

      Hey! This is a question that always gets people in my department chatting furiously!

      My degree was in Astronomy, so I’d hope I’d be able to tackle this.

      The Big Bang is all about how the Universe expanded really quickly. Imagine if the universe was a spotty balloon, as you blow it up it gets bigger and all the spots get bigger and slowly move away from each other.

      But the Big Bang doesn’t try to explain what happened before the Universe. Or even how it started. There are a few ideas going around, but none really solve the problem.

      The biggest idea is that before the Big Bang everything was completely smushed together, so much so that all of physics kind of broke down. Up would be down. Left would be right. Drinking orange juice after brushing your teeth would taste good. The thing about this is that in that situation, time would break down too, it wouldn’t really do anything. So there was no before the Big Bang, because time didn’t make sense.

      A lot of people don’t like this answer because it’s so hard to test right now, which goes against what science usually is, but it’s still one of the best ideas we have. Thank you for your question

    • Photo: Jessamyn Fairfield

      Jessamyn Fairfield answered on 10 Nov 2013:

      Before the Big Bang, more than 13 billion years ago, our universe was a singularity: infinitely hot and dense matter in an incredibly small space. We can extrapolate backward to that point using the laws of nature we know, like general relativity, but the physics of the singularity would have been totally different than how things are now.

      The Big Bang itself was the sudden expansion of that singularity, and while we see lots of evidence in the cosmos for the Big Bang itself, we don’t know what triggered it. So far, while there are many competing theories, we haven’t made any observations that support one over the others. This is partly because the Big Bang itself involved so much heat and energy that it’s hard to measure what came before.

      And of course, so far we can only try to measure the things happening in our universe before the Big Bang. There might have been other singularities, or other universes, that we don’t yet know how to measure or interact with. We don’t have a way to know what happened in them before the Big Bang!

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