system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do some fridge magnets fall off after a certain time? Do magnets lose magnetic properties?
gpt
Magnets do lose strength over time. Basically, the magnet is made up of a bunch of microscopic magnets. The magnet is at it's strongest when all the microscopic magnets are pointing in the same direction. Heat causes some of the microscopic magnets to flip in a random direction, which, on average, reduces the strength of the magnet. A lot of heat can cause the magnet to stop being magnetic rapidly, a small amount of heat (like room temperature) means the magnet loses strength more slowly. Your fridge magnets that fall off are either old or just made with bad magnets.