Atoms and Molecules

History of the Big Bang


The Universe started with the Big Bang about 14,000 million years ago (14,000,000,000 years). It started out very, very hot and has been expanding and cooling since then.

For the first tiny fraction of a second, everything was so hot, that we cannot describe what it was like, but we can use our knowledge of physics to give us a good idea of what was happening from as little as 10-43 seconds (that is 0.0000000000000000000000000000000000000000001 seconds!) after the beginning.

Big Bang

The evolution of the Universe.
Credit: NASA

The Big Bang is the explanation for how the Universe started. Astronomers think that everything started in a single point. Then everything expanded and stretched to grow into the huge Universe we see today.