I'm reading Taylor and Wheeler's, Exploring Black Holes.(adsbygoogle = window.adsbygoogle || []).push({});

I was doing okay until I reached their derivation of energy in Special Relativity.

They arrived at this equation:

[tex] \frac{t}{\tau} = \frac{E}{m} [/tex]

Tau is proper time, t is the frame time, E is energy and m is mass.

The authors used the Principle of Extremal Aging to derive the equation. How did they arrive at E/m as a constant of motion?

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# Energy in Special Relativity

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