system
Given the following post, respond as if you're commenting on Reddit:
human
Is the Earth's rotation still slowing down? If so, could it eventually stop?

In one of my earth and atmospheric sciences classes we learned that the length of the average day was 21h (based on coral growth fossils I think) and it has been slowing down ever since. How slow can it get?
gpt
Given an infinite amount of time, the limit would be that it would become tidally locked to the moon (like the moon is to the earth), so that a day would last a month (which would actually be longer than it is now).  In actuality, the sun will become a red giant and earth will either be consumed or be rendered unable to support life long before that happens.