Most astronomers believe that the big bang created the universe about fourteen billion years ago. At that time our universe was in this bubble that was so small that it was smaller than a pinhead. It was so hot and so dense that it hasn´t ever been before we´ve seen before. Then it exploded and the universe we live in was created. Time, space, and matter all began, because of the big bang. In a fraction of a second, the universe grew from an atom to bigger than the Milky Way. The universe is still expanding today and as it got cool the energy changed into particles of matter and antimatter. These two different particles destroy each other. Some of the antimatter and matter survived. Some of the more stable particles called protons, and neutrons formed when our universe was a second old. In fourteen minutes, the temperature dropped one billion degrees Celsius. It finally was cool enough so that the protons and the neutrons could come together which formed, hydrogen and helium nuclei. 300,000 years went by and it cooled down to 3,000 degrees. Atomic nuclei started clumping collecting electron s so they could form more atoms.