## Conceptual Physics (12th Edition)

Gamma $= \gamma = \frac{1}{\sqrt{1-\frac{ v^{2} } { c^{2} }}}$. This is never less than 1 because $\frac{v^{2}}{c^{2}}$ is always positive and less than or equal to 1. The denominator is always positive and less than 1, so its inverse (or reciprocal) is always greater than or equal to 1. This is discussed on page 666.