Cosmology

Where was the Big Bang?

Where did the Big Bang take place? If the Universe is expanding, where is it expanding from? These are very good questions, but the answer might seem confusing. The answer is...everywhere!

It is all in the dimensions!

The Fate of the Universe

One of the biggest questions in science is "What will happen to the Universe"?

The Universe began with the Big Bang about 14,000 million years ago (14,000,000,000 years). When it was young, the Universe was very, very hot and dense. Since then, it has been cooling down and getting bigger.

Evidence for the Big Bang

Astronomers think the Big Bang is the best way to explain how the Universe started and how it changed over time. All science is based on evidence. So what is the evidence for the Big Bang?

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.

Expansion of the Universe

When we look at galaxies which are far, far away, we see they are all moving away from us. And, the further away the galaxy is, the faster it is moving. This is happening because the space between the galaxies is stretching.

Redshift

Most galaxies appear to be moving away from us. This means that the light from them is "stretched" slightly and appears a bit redder than it would otherwise do.

This is similar to what happens to sound. Imagine that a fire engine is driving past you with its siren on. When it is moving towards you, the siren it quite high-pitched. When it is moving away from you, the pitch drops, and it sounds lower. With light, "lower" means more red and "higher" means more blue.