#10: Wolfgang Pauli
Wolfgang Pauli was once asked to critique a paper of questionable merit. As he is said to have put it, “This is not right. It is not even wrong.” It was a good and concise statement of what physics requires – not merely interesting ideas, but ones that are both grounded in experimental reality and theoretical rigor. Ideas which don’t do both are not even wrong. There’s even a a physics book in the popular press today titled after Pauli’s quote, making the titular claim about string theory.
But of course snappy quotes won’t get a scientist on the top ten list. Pauli earned his place in more than one dramatic way. The first is his idea that particles have an internal intrinsic degree of which we call spin. It serves as a distinct quantum number, doubling the number of possible states for an electron. This is a vitally important concept because no two electrons can exist in the same quantum state – which is itself another discovery of Pauli, now named the Pauli exclusion principle in his honor. For this discovery he was awarded the 1945 Nobel Prize in physics.
He calculated the spectrum of hydrogen and invented the Pauli spin matrices, which are fundamental for treating the quantization of spin angular momentum and are familiar to any student of quantum mechanics.
He predicted the existence of the neutrino in order to explain why certain quantities seemed not to be conserved in beta decay. As you might have expected, he was very worried about having predicted something unobservable, but later in life he was proved to be correct when delicate measurements were able to confirm the existence of the neutrino directly.
He died in 1958 at the age of 58. In that lifetime he discovered several fundamental principles of nature, made successful predictions on the basis of theory, proved importent physical theorems, and broke lab equipment with his mere presence (the mark of any fine theorist!). A scientist can’t ask for a much better legacy.