system
Given the following post, respond as if you're commenting on Reddit:
human
How can the "Big Crunch" idea work, if all objects are moving away from one another, and gravity weakens as distance apart becomes greater?
gpt
Gravity never stops acting between two bodies. It gets weaker as you travel away but there is always some force.

The idea behind the Big Crunch model is that eventually the expansion of the universe will halt, thus bodies will no longer be moving away from each other. As gravity will still remain, bodies will move towards one another and over time this will result in all the mass forming a single body.

However, as far as we know, the expansion of the universe is actually accelerating, not slowing down or stopping; hence the Big Crunch model seems less likely at this point.