# Tag Info

The laws of conservations of momentum and energy combined forbid the reaction $$e^- + \gamma \rightarrow e^-$$ (Go ahead and do the math, is simple and enlightnening). But a completely different story is: $$e^- + \gamma \rightarrow e^- + \gamma$$ Where the incoming photon has a different energy that the outcoming one. And also, you can have an ...