The Big Bang

The Beginning of the Beginning

The Big Bang is a theory that scientist have developed to explain how the universe started. Before the universe was created, all matter existed as a speck smaller than an atom. It was dense and vey hot, at around 1 billion degrees. The laws of physics, electromagnetism, or gravity, did not exist at this time. 

Around 13.7 billion years ago, this single point exploded, creating all matter, energy, space and time.  The explosion also caused super-hot matter to expand and spread. As these particles cooled, they formed elements such as hydrogen and helium. Eventually, stars formed along with galaxies and planets as the universe expanded. 

A Belgian priest named Georges Lemaitre first developed the big bang theory in the 1920s, when he theorized that the universe began from a single atom. This idea was supported by Edwin Hubble's observations that galaxies are drifting apart in all directions.  The discovery of cosmic microwave radiation in the 1960s also help support Lemaitre's idea.