system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Egg in A Bottle Experiment

I don't really grasp the concept. I figure it has something to do with pressure, but what is the actual science behind it?
gpt
It's quite simple actually. Hot air expands, and cold air shrinks. Thus, first you warm up the air in the bottle, causing it to flow out. Then, you block the bottle by putting the egg on it.

As the air cools down, the pressure inside drops, and it sucks the egg in.