Seven Brief Lessons on Physics

by Carlo Rovelli

Another of the consequences of the theory, and one of the most spectacular, concerns the origins of the universe. We know how to reconstruct the history of our world back to an initial period when it was tiny in size. But what about before that? Well, the equations of loop theory allow us to go even further back in the reconstruction of that history. What we find is that when the universe is extremely compressed, quantum theory generates a repulsive force, with the result that the great explosion, or “big bang,” may have actually been a “big bounce.” Our world may have actually been born from a preceding universe that contracted under its own weight until it was squeezed into a tiny space before “bouncing” out and beginning to re-expand, thus becoming the expanding universe that we observe around us. The moment of this bounce, when the universe was contracted into a nutshell, is the true realm of quantum gravity: time and space have disappeared altogether, and the world has dissolved into a swarming cloud of probability that the equations can, however, still describe.