system
Given the following post, respond as if you're commenting on Reddit:
human
What will happen to a galaxy towards the end of its existence?

Will the universe eventually just be comprised of a bunch of "dead" galaxies? I hear some galaxies will collide and interact. If a galaxy were to never collide or interact with another space entity, what would eventually happen to it?
gpt
The galaxies will just get dimmer and be full of dead bodies, as no more stars can form in them. Spacetime will still allow for gravity so it will still be bound. Eventually though the galaxies themselves will cease to be as they go through proton decay - this won't be until the black hole era - when only black holes will be able to keep themselves together. Then eventually they will also evaporate.