Big Bang Theory

I'm sure somebody will explain it better than I can but here goes...

The 'big bang' wasn't an explosion of matter *into* space, rather it was the
expansansion of space itself - and it's still expanding today.

There is no 'outside' of the universe, as in the same way there is nowhere
north of the north pole (as Hawking once put it), so it is unlikely the
expansion is being fed from an external source.

However, it is possible there is a driving force behind the expansion of the
universe. We have recently discovered the universe is expanding faster and
faster rather than slowing down, so it is assumed there is a 'dark energy'
accelerating matter further apart over large distances - a sort of
anti-gravity.

Dark matter is the term used to describe the extra amount of matter we can't
detect through our telescopes but we can tell is there from the way galaxies
rotate. It appears there should be more matter than we can currently see,
so the stuff we can't see we call dark matter.

I think that's roughly correct, anyway!
Paul.