Future scenarios
Open: everything gradually runs down in a dilute cold future
Critical: same as in open, except space-time becomes flat on large scale
Closed: everything collapses back to a hot “big crunch”
How can the “big crunch” happen?
- If there is enough mass gravity can pull things together again!
- Note: It is not that the universe collapses in a fixed space. Gravity pulls space itself together.