system
Given the following post, respond as if you're commenting on Reddit:
human
I just wondered if E=mc2 and light has no mass E=30000000*0=0 so wouldn't that mean light has no energy. This is probably wrong but why is it?
gpt
The full equation is E^2 = p^2 c^2 + m^2 c^4 . If a particle is at rest it simplifies to E=mc^2 . However, light can never be at rest, and has no mass, so its equation simplifies to E=pc. Now the reason E=mc^2 is so popular is because we'd never imagined a particle at rest had energy just in its own existence. We'd always figured energy had to be kinetic like 1/2 m v^2 , or potential energy like mgh.