According to Einstein E²=(mc²)²+(pc)². In the case of photons m would be equal to zero since photons are massless, so the equation simplifies to E²=(pc)². p represents momentum but because p=mv and mass is still zero, p would also be zero. Therefore E should also be equal to zero, but this doesn’t make sense since light must have energy (eg. solar energy). I hope I’ve explained my thoughts clearly and thanks to anyone who can help me understand.
In: Physics
> because p=mv and mass is still zero, p would also be zero
p=mv is from Newtonian mechanics, which is a good approximation to Relativistic physics, but only when the objects involved are massive and not moving at a significant fraction of lightspeed. E²=(pc)² (which further simplifies to E=pc) is not an indication that photons have no momentum, but an indication that the momentum of a massless photon is directly proportional to the photon’s energy.
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