According to my Physics' teacher, photons do have a mass, but according to the relativity theory, moving anything with the speed of light would take an infinite amount of energy.
Now, anything with energy must have a mass, and according to the Quantum theory, it technically means that anything larger than a photon could never move at the speed of light, since Photons ARE the speed of light.

Can anyone help me get these things straight?
I think the Quantum Physics explanation is right, but I need it for my game engine.

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