Saturday, November 17, 2012

Anniversaries: Wigner, Néel, Hofstadter

On November 17th, I usually dedicated space to the anniversary of the 1989 Velvet Revolution, the beginning of the fall of communism in Czechoslovakia, which occurred on the 50th anniversary of the clash between Czech students and the Nazi regime in 1939, a clash from which the students emerged (in 1,200 cases, in concentration camps) as losers (temporarily).

However, physicists are being born and dying on November 17th, too.

In 1990, Robert Hofstadter died. He was born in 1915 into a family of a salesman, studied or was affiliated with CUNY, General Electric, Princeton, Upenn, and most recently Stanford. He is the grandfather of a fictitious grandson, Leonard Hofstadter, who is famous for being Sheldon Cooper's roommate, and the father of a Pulitzer-winning author Douglas Hofstadter.




Hofstadter got his 1961 Physics Nobel Prize together with Mössbauer for "electron scattering off nuclei". So you may imagine the type of work he has done. Amusingly, he became the father of the units "fermi", 1 fm, in 1956. This is a clever unit because "fm", which is \(10^{-15}\) meters, seems like an acronym for "Fermi" who studied lots of things whose typical distance scale is 1 fm. However, 1 fm may also be read as "one femtometer" where "femto-" is a general prefix representing \(10^{-15}\). The prefix "femto-" has a justification independent of Enrico Fermi: it comes from Danish "femten" for "fifteen". Note that it looks like a mutated "fifteen" or "fünfzehn". ;-) In his late years, Hofstadter got interested in astrophysics and was one of the fathers of the Compton Gamma Ray Observatory.

Louis Néel was born in Lyon, France on November 22nd, 1904, and died on November 17th, 2000. He got his 1970 Physics Nobel Prize for the discovery of antiferromagnetism, ferrimagnetism, and the Néel temperature at which the former magnetic behavior stops. His comments on the magnetism of rocks also made it possible to study the evolution of the geomagnetic field.

Of course, I think that the most important anniversary is the November 17th, 1902 birth of Eugene Wigner (who died in 1995). Note that almost all the cofathers and near-cofathers of quantum mechanics were born in the first years starting with 19**: Pauli *1900, Heisenberg *1901, Dirac *1902, Wigner *1902, von Neumann *1903. Not too shocking that these guys who could be classmates viewed Bohr *1885 as a kind of a father. ;-)

At any rate, Wigner was born in Budapest to a middle-class Jewish family. When he was 11, he was sent to a sanatorium with an apparent tuberculosis. He started to love math problems over there. His family escaped Hungary (to Austria) in 1919 when the country was hijacked by communist assholes. They also converted to Lutheranism, not because of their love to the Christian God but because of their hatred towards communism. ;-) As you can see, "Jewish" doesn't have to be equal to "communist"!

While he studied chemistry in Berlin, he could see folks like Planck, von Laue, Ladenburg, Heisenberg, Nernst, Pauli, and Einstein. Leó Szilárd was Wigner's best friend for quite some time. Wigner began to contribute to quantum mechanics in the 1920s as an assistant to mathematician David Hilbert in Göttingen. He also found a wife for Paul Dirac, namely his own sister. It just happened that Wigner was hired by Princeton before the rise of Hitler, in 1930 (his affiliation with Princeton was interrupted in 1936-1938). He was an important guy behind the scenes of the Einstein-Szilárd "pro-nuclear-bomb letter" to FDR which led to the initiation of the Manhattan Project.

Wigner was a polite guy. When he was cheated by a used car dealer, he kindly advised him to "go to hell, please".

Some of his musings on philosophy of quantum mechanics looked almost spiritual and he got actually involved not only with some "biology as being more fundamental than physics" memes but even with Hinduism. But lots of the important things he has done are completely solid insights – about the angular momentum conservation and its consequences in quantum mechanics; parity conservation law; scattering in quantum mechanics; resonances in quantum mechanics; related distributions and Wigner's general quasi-probabilistic distribution; Wigner's friend as an improvement of Schrödinger's cat. I like this Wikipedia list of things he is famous for:

Law of cnservation of parity
Wigner D-matrix
Wigner–Eckart theorem
Wigner's friend
Wigner semicircle distribution
Wigner's classification
Wigner quasi-probability distribution
Wigner crystal
Wigner effect
Wigner–Seitz cell
Relativistic Breit–Wigner distribution
Modified Wigner distribution function
Wigner–d'Espagnat inequality
Gabor–Wigner transform
Wigner's theorem
Wigner distribution
Jordan–Wigner transformation
Newton–Wigner localization
Wigner–Seitz radius
6-j symbol
9-j symbol

With this list in mind, it's really shocking that he couldn't "believe" when he got his 1963 Physics Nobel Prize (for insights about the nuclei and symmetries in particle physics; the other half went to Maria Goeppert-Mayer and J. Hans Jensen for the nuclear shell model). He thought he could only appear in the newspapers after he would do "something wicked". He died in 1995.

Dozens of TRF articles have mentioned Wigner.

4 comments:

  1. Nice article, Wigner obviously was a cool guy too apart from a great physicist:

    Wigner was a polite guy. When he was cheated by a used car dealer, he kindly advised him to "go to hell, please".


    This sentence made me LOL :-D


    And before I read this article, I thought Lumo created "Wigner's friend" in the context of another TRF article ... :-)

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  2. Dear Lubos, I searched the TRF archives for previous Wigner articles but found only the briefest mention of his "The Unreasonable Effectiveness of Mathematics in the Natural Sciences". Is this not an interesting question to you? Perhaps because others have already said all there is to say -- if so, what writings would you recommend? Or can we hope for a future TRF article on this subject?

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  3. Thanks for the tip. It's of course interesting enough and Wigner is very wise on that issue.

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  4. One of Wigner's great contributions to physics (after Weyl) was his promotion of group theoretic methods with his book 'Group Theory and its application to the quantum mechanics of atomic spectra' originally published in german in 1931(!) but only translated to english in 1959.

    (A google search for the title with 'djvu' appended may give you a downloadable version)

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