system
Given the following post, respond as if you're commenting on Reddit:
human
If photons are mass-less, then why does gravity affect light?

How does gravity affect mass-less particles?
gpt
Gravity isn't just an attraction between masses, it's the way the paths-of-least-resistance through space and time, which light follows, are modified by the presence of energy. So, the "straight line" path that light follows gets curved by the presence of a star or planet.