What is the spin of a particle?
In: Physics
Imagine you have a collection of balls, and they differ in three ways: some are red and some are green; some are big, some medium, some small; some are heavy and some are light.
To uniquely identify a type of ball you clearly need three pieces of information: colour, size and weight. But you don’t need the exact value on a continuous scale; just knowing that a ball is “big” is sufficient. These properties are “quantised” which means that they can only take certain values.
Well it turns out that subatomic particles can also be sorted into types by specifying the value of a number of quantised parameters, called “quantum numbers”. So for example an electron needs 4 numbers to describe it. One number corresponds to how much energy the electron has, and two correspond to the pattern it makes as it goes round the nucleus. The fourth number doesn’t really correspond to anything we can easily describe, but it got called “spin”.
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