Identical Particles: Feynman's Physics Explained
There is a strange, beautiful rule for identical particles like electrons or photons. If a process can happen two ways that differ only by swapping two identical particles, you must combine their amplitudes. For bosons (like photons) you add them; for fermions (like electrons) you subtract. That single minus sign for fermions is the origin of the Pauli exclusion principle — no two electrons in the same state — which gives us the periodic table and the very stability of matter.
The big idea
A single minus sign for electrons builds the entire periodic table.
Think about it
If electrons could pile into the same state, what would happen to the structure of atoms — and of you?
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