Einstein’s relativity theory and quantum theory are two pillars of modern physics that have each been shown to work well in their respective regimes. All currently observed physical effects fall well ...

A theory developed by Albert Einstein stating that the laws of motion are the same for all inertial (non-accelerating) frames of reference and that the speed of light (in a vacuum) is the same for all ...

What does this mean for mass measurements? Basically the reason we can't travel faster then C (afaik) is because of the way relativistic velocities add. ie .8c +.2c +.2c +.2c = .935 c or something ...