Normally we consider the universe, everything, and time itself as having begun at the moment of the big bang, but what happened before the big bang? According to work by Maurizio Gasperini and Gabriele Veneziano, the universe may have begun in a cold state, stretching out infinitely. An instability kicked in, causing every point to rush away from every other, inducing space to curve, the temperature to increase, and the energy density to grow. In this situation, a millimeter patch of three-dimensional space could account for our whole universe pre-big bang.

In another theory by André Linde, the outburst of inflation in the previous theory may not have been a singular occurrence. Instead, this happens in isolated areas around the cosmos creating new universes, and in each of these universes more universes can errupt. This idea is called a multiverse, in which there are several universes other than ours. The physics in each could vary, leading to unimaginable differences between our universe and others. Most of these would be likely unable to support life, at least as we know it.

Lee Smolin extended this theory by proposing that, given the similarities between black holes and the big bang, perhaps every time a black hole is created, a universe is born. He suggested that these baby universes are very similar to the parent universe, with slight differences. The ultimate goal of this evolution would be to produce a universe ideal for black hole creation. If this is correct, it would seem that the properties of our universe would be near-ideal for creating black holes. If we were to mess with these properties, it should make it more difficult for black holes to form. This idea is currently under investigation.