The Big Bang was the beginning of space and time, as many physicists believe today. Note that this is only a theory and has not yet been proven, but several key observations have been made that support it. In the beginning of our time frame, all of the matter that exists today in the universe was packed into a single point in space-time, known as a singularity. A singularity is a point that has infinite density and is infinitely small. At one moment, all of this matter exploded outward in what is called a Big Bang. This matter has been expanding and forming different structures ever since.