system
Given the following post, respond as if you're commenting on Reddit:
human
Since m = E/c^2, how can photons have energy, but no mass?

If I understand correctly, mass is actually an indication of the amount of net energy an object contains. How is it then possible for a massless object to contain energy?
gpt
E=mc^2 is true for objects at rest, but photons are never at rest. The full equation is E^2 = (mc^2 )^2 + (pc)^2 , where p is the momentum. So, for massless particles like photons E=pc, i.e. their energy is related to their momentum.