Built on Facts

#10: Wolfgang Pauli

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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.

Comments

  1. #1 Uncle Al
    September 18, 2008

    both grounded in experimental reality and theoretical rigor.

    String theory, SUSY. “Das ist nicht nur nicht richtig, es ist nicht einmal falsch!” There is no empirical evidence for either. Both require deep symmetries (BRST invariance and conservation of angular momentum, respectively) that can be violated without contradicting prior observation in any venue at any scale.

    (Example: isotropic vacuum plus Noether’s theorem demands conservation of angular momentum. Parity is not a Noetherian symmetry. A chiral vacuum background in the massed sector is invisible to EM and common matter. Chemically identical opposite parity mass distributions will violate conservation of angular momentum, left foot fitted by left and right shoes. Chemists challenging a chiral background with enantiomers observe diastereotopic results – Sepracor $billion-busting pharma patents with resolved chiral drugs. Physicists should look.)

  2. #2 Chris
    September 18, 2008

    I hadn’t heard of the Pauli Effect. I’ve got that in spades. Maybe the fact that my boss keeps confusing me for a physicist (I’m an engineer) is a sign.

  3. #3 Joe
    September 18, 2008

    The exclusion principle that was invoked ad hoc by Pauli still lacks some kind of intuitive elementary explanation: Why is there a fundamental relationship between intrinsic spin and statistics? I believe that Feynman pointed out in one of his famous lectures that since he could not produce such an intuitive connection we do not really understand this thing as well as we should. This is still an area of active research today.

  4. #4 Tristram Brelstaff
    September 18, 2008
    He calculated the spectrum of hydrogen…

    According to Bartels van der Waerden (“Sources of Quantum Mechanics”, 1967) it was Pauli’s 1926 paper on the hydrogen spectrum that convinced most physicists that the new quantum mechanics was correct.

  5. #5 Alex
    September 18, 2008

    What a stud.

  6. #6 Yuri Danoyan
    September 18, 2008

    What is your opinion of my Pauli thread?

  7. #7 Anonick
    September 18, 2008

    In my opinion, Pauli deserves a top 5 position atleast, but your top 9 are yet to be unveiled. :)

    Pauli was an awesome theorist, and unlike his friends engaged in the development of QM, he had a strong classical base. When he was just 21, he wrote an essay on GR that even Einstein praised. And he was very respected as a critic (“What would Pauli say?”).

    Nice post. I’m especially excited about the #1 position. ;)

  8. #8 Tom
    September 19, 2008

    I TA’d for a professor who had had Pauli as a professor in school. The story he told us about Pauli started with (and one must imagine this with a clipped Austrian accent) “Wolfgang Pauli was my electrodynamics professor. He was a real bastard.”

  9. #9 IBY
    September 19, 2008

    What are spins represent? Are they just mere abstractions or a physical property?

  10. #10 CCPhysicist
    September 19, 2008

    One other characteristic of Pauli is that he wrote very few papers with collaborators. Sort of the antithesis of the late mathematician Paul Erdos, who had hundreds of them. So while there are many mathematicians with a small Erdos number, very few physicists have a small Pauli number.

  11. #11 Santiago Killing
    October 2, 2011

    Importent?

  12. #12 naveen theja
    October 23, 2011

    were is nikola tesla !

  13. #13 Andrew
    March 30, 2012

    What about Galileo?????

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