If two particles have velocities v1 and v2 in a rest frame, how do we prove that the relative lorentz factor is given by :(adsbygoogle = window.adsbygoogle || []).push({});

γ(r)=γ(1)γ(2)(1−v1.v2)

and why is this quantity lorentz invariant

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# Relative Lorentz Factor

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