Relativistic Energy and Momentum: Feynman's Physics Explained

Feynman Vol I7-8

If space and time are relative, other quantities must change too, and Newton's laws need modifying. An object's mass increases with its speed; as it approaches the speed of light, its mass heads toward infinity, which is why nothing with mass can ever reach that speed. The most famous consequence is E = mc^2: mass is a fantastically concentrated form of energy. The energy released by an atomic bomb is simply a tiny bit of mass converted directly into energy.

The big idea

Mass and energy are the same thing in different forms: E = mc^2.

Think about it

A tiny amount of mass holds a huge amount of energy. What does the c^2 (the speed of light, squared) tell you about how much?

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