Question

why einstein say e=mc

Answer 1

Einstein say e= mc2, i.e., mass is energy

Answer 2

lets say neutrion is faster than light, will e still equal mc^2?

Answer 3

this equation is true for particules which has light speed
so if there is a roletivistic particule it's energy will be depend on it's mass and it's speed's square root

Answer 4

\[E=mc ^{2}\] simply says that mass and energy are not two sperate things. They are just the one and same thing. That is we prefer to call something mass if it looks like particle and we prefer to call it energy if it is in the form of radiation for example. But this "it" is simply what we may call mass-energy.