system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What causes water bottles to randomly pop in the middle of the night?
gpt
Two things can do that to a sealed/closed bottle: a change in ambient temperature or a change in ambient pressure. If it's just sitting there and you're not on a plane changing altitude or a cable car going up a mountain, pressure is unlikely to change. The most likely cause then is temperature. It drops over night for example, which cools off the bottle and it's content, this drops the pressure (because less temperature = less kinetic energy of gas phase water molecules and air in the bottle = less pressure these molecules exert on the bottle wall = atmospheric pressure no longer balanced with inside pressure = outside pushes inside = dent.)