TranscriptQuestion: Does it make sense to ask what preceded the Big Bang?
Katie Freese: I think people have the misconception that the big bang is the universe starting from a point. In fact, it is very different from that. Probably you know that the Universe is expanding, so if we go backwards in time then you can watch the Universe contract as you go backwards in time. So for example, if you took a tabletop then any two points would get closer together, but the points that are way far apart if you had… Let’s say it’s an infinite tabletop, so as these points get closer and closer together you still have a tabletop that is infinite in extent. It’s not like everything comes into one point, but eventually you reach such a high density. Things are so compact and right on top of each other that we lose our description. Physics fails. That is what the big bang is, so it’s actually we would need to have a theory of quantum mechanics and gravity simultaneously to be able to discuss physics going backwards in time any further, so it is really a high density situation that we call the big bang, but there is really no explosion. There is no bang. There is no singular point. But so yes, it does make sense to ask well what happens when you reach that density and that is what people are trying to do in theories of quantum gravity such as string theory or well some of the cosmology that I’ve done also is in the context of brains where our observable universe is living on a three dimensional surface in a higher dimensional universe and there could be other brains out there and how these brains intersect one another and their motions and so on has been… So there are different avenues to try to push back our level of knowledge and they are very active, but very difficult.
Everything was more dense and then there is a certain point where… which we call the big bang and it’s from that point forward that we start our clocks, so that’s… And then so and we say the universe is 13.7 billion years old is relative to that very high density situation.
Recorded May 7, 2010
Interviewed by David Hirschman