Spin and the quantum rules for apartment rentals

Almost all elementary particles act as if they are spinning. Scientists once believed that this spin would always be 0, 1, 2… measured in the units of quantum mechanics. Yet the spin of electrons turned out to be ½. Moreover, particles with spin ½ can’t really share space with each other. This fact shapes the entire physical world.

What’s in a spin ½? Picture the locations available to electrons as apartment rentals. The rules for renting determine the structure of atoms and molecules. If electrons had spin 0, sharing would not just be allowed, but desired. All electrons would end up sharing the same apartment, with dire consequences.

Speaker: Robert Cahn, UC Berkeley