= Lorentz factor
{c}
{title2=$\gamma$}
{wiki}
For a relative <speed> $0\leq v<c$, the <Lorentz factor> is
$$
\gamma=\frac1{\sqrt{1-v^2/c^2}}.
$$
At $v=0.6c$, $\gamma=1/\sqrt{1-0.36}=1/0.8=1.25$. Thus a moving clock accumulates $0.8$ seconds of <proper time> per laboratory second, and a parallel moving rod has $0.8$ times its rest length. The <Lorentz factor> approaches one at small <speed> and grows without bound as $v$ approaches the <speed of light>; a massive object's <rest frame> never requires a boost at $v=c$.
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