Special Relativity: A theory proposed by Einstein that describes the physics of objects moving at constant high speeds close to that of light.
Lorentz Factor:$$\gamma = \frac{1}{\sqrt{1-\frac{v^2}{c^2}}}$$, a factor that appears in several equations in special relativity and accounts for time dilation and length contraction.
Rest Mass Energy: $E_0 = mc^2$, which represents the intrinsic energy contained within an object's rest mass.