Classically, probability can be described using axiomatic set theory, where probabilities are related to the(adsbygoogle = window.adsbygoogle || []).push({}); cardinality(size) of the sets involved.

For a quantum probability, the probability of a particular state is the squared magnitude of the wave function (eigenfunction) for that state's eigenvalue.

Relating this back to sets, what sort of a set has a complex number representing its cardinality? Or, more specifically, how can a complex number represent the "size" of a set?

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# Quantum Probabilities

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