What does Red Shift tell us about the Universe?

So galaxies far away are moving away from us.

In 1929 Edwin Hubble came up with Hubble's Law. This states that the recession speed of a galaxy is proportional to how far away it is. So galaxies quite close to us are moving away slowly. Galaxies very far away are moving away very quickly.

The Big Bang
In 1922 Alexander Friedmann first suggested the Big Bang theory. Here was evidence for it. If all galaxies are moving away from each other then at some time in the past they must have been very close to each other. Perhaps the Universe started as being very small and has been expanding ever since. As well as getting bigger the Universe has also been cooling down.

From the graph above we can work out the age of the Universe. It turns out to be about 14 billion years old.

Some important points

Our galaxy is NOT the centre of the Universe. All galaxies are moving away from each other, not just us. Imagine a loaf of raisin bread baking and swelling. All the raisins move away from each other.

Some nearby galaxies are actually moving towards us. In a few billion years we may collide with the Andromeda galaxy.

Time began at the big bang. There was no before.

Space stretches as the Universe expands. There is no "other side" as far as we know.

There is much still to learn.