An astrophysical theory of the beginning of the Universe. It suggests that the Universe began in a very tiny region of space, and exploded outward. Astrophysicists believe that this occurred roughly 14 billion years ago. Other astrophysical theories for the beginning of the Universe — like the Braneworld theory — exist, though none is as thoroughly studied and supported by the data as the Big Bang model. Scientists have no idea what came before the Big Bang.