Our Universe may have begun not with a bang, but a bounce.
New research and mathematical models are helping astronomers to understand the beginning of our Universe like never before. The Big Bang Theory has been the best model for the beginning of our Universe for a long time, but a new theory may be taking its place. This theory is called the Big Bounce.
Loop Quantum Gravity unifies Einstein's Theory of General Relativity with equations of quantum physics to produce the Big Bounce. Scientists can now use mathematical means to look back in time to before the Big Bounce and see what our Universe came from. It ends the closed door of a Big Bang because with a Big Bounce the minimum volume is not zero and the maximum energy is not finite, allowing scientists to calculate and "see" farther back.
That peek into the place from which our Universe sprung shows another Universe. This Universe was similar but not exactly the same as ours. It seems to have collapsed in a Big Crunch (one of the possible endings to our own Universe) before bouncing back outward and creating the new Universe we see today.
But the new calculations reveal a "cosmic forgetfulness" at the time of the Big Bounce that will keep us from ever knowing all the properties about the earlier Universe.
Our own Universe is not believed to be heading toward a Big Crunch as was once speculated on. It appears that it will never create a Big Bounce of its own, because the Universe will never collapse in on itself. The Universe is expanding, and not only that, but the rate of expansion is increasing. The Universe is moving like a runaway train. One day it may end in a Big Rip, when all the matter is torn apart as it expands, even overtaking gravity that holds objects together and annihilating galaxies, stars, and planets.
