system
Given the following post, respond as if you're commenting on Reddit:
human
If light photons have no mass, how can a black hole exert a gravitational force on them?

Maybe I'm misunderstanding the idea that light can't escape a black hole because of the immense gravity. Someone please explain.
gpt
Because gravity isn't *actually* a force that acts between two massive bodies (though that's a very good approximation, for the most part). It's what happens when mass and energy curve spacetime. When spacetime is curved, anything that tries to travel on a straight line will end up on a curved path, and we see that curved motion (through space *and* time) as gravity. So photons are affected by gravity simply because they, like everything else, live in spacetime.