How is the universe expanding?

1 Answer
Dec 8, 2017

As a result of the initial ‘explosion’ we call the Big Bang.

Explanation:

Since then the expansion has generally slowed as the only long range force in the universe is gravity which (so far as we can tell) is always attractive.

More recent evidence (Perlmutter amongst other in 1998) suggests that this expansion has been increasing more recently due to the effects of dark energy overcoming the force of gravity.

A most amusing physicist described this as being ‘like dark matter, but significantly less well understood’ (we seem to have no clue whatsoever about dark matter.)