How deep is the universe?

Answer

The deepest we can see into the universe is about 40 billion light-years away. That’s the greatest distance light from a source can have traveled since the universe came into being, about 13.7 billion years ago.

It may sound a bit strange that you can see three times as many light years away than the universe is in years old. That’s because the universe is getting bigger: the distance that is now 40 billion light-years, used to be shorter.

Those 40 billion years are immediately the size of the ‘visible universe’. It is quite possible (even probable) that the universe is much bigger than that, but we can’t see that; we have to wait until the universe is a bit older for that.