Where did the big bang come from?

The Big Bang

Most astronomers assume that the universe was formed around 14 billion years ago with a big bang, the Big Bang. At that time, the entire universe was in a bubble a thousand times smaller than the head of a pin. It was hotter and denser than we can even imagine.

Suddenly the bubble exploded and the known universe was born. Space, time and matter - it all started with the Big Bang. In just a fraction of a second, the universe had expanded from not even the size of a single atom to a space larger than a galaxy (Milky Way). And it continued to grow at an incredible pace. The universe is still expanding today.

As the universe expanded and cooled, the energy turned into particles of matter and antimatter. These two opposing types of particles largely destroyed each other. However, a certain amount of matter survived. When the universe was a second old, more stable particles formed, which we call protons and neutrons.

Over the next three minutes, the temperature dropped below 1 billion degrees Celsius. So it was 'cool' enough for the protons and neutrons to combine. This created hydrogen and helium nuclei.

300,000 years later, the universe had cooled to around 3,000 degrees Celsius. At last atomic nuclei could capture electrons and thereby form atoms. The universe filled with clouds of hydrogen and helium gas.

Last modified December 15, 2004

History of the universe