Quasars may be the brightest objects in the universe, but gamma-ray bursts can be even more powerful for a short period of time. It is hypothesized that a gamma-ray burst in the Milky Way aimed at Earth could wipe out humanity.
Nearly 14 billion years ago, due to a random fluctuation in a completely empty void, a universe exploded into existence. Scientists call this the Big Bang theory for the origin of the universe. But there are other theories .