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Hendrik Casimir

Currency:USD Category:Collectibles / Autographs Start Price:NA Estimated At:6,000.00 - 8,000.00 USD
Hendrik Casimir

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Auction Date:2018 Jun 13 @ 18:00 (UTC-5 : EST/CDT)
Location:236 Commercial St., Suite 100, Boston, Massachusetts, 02109, United States
ALS - Autograph Letter Signed
ANS - Autograph Note Signed
AQS - Autograph Quotation Signed
AMQS - Autograph Musical Quotation Signed
DS - Document Signed
FDC - First Day Cover
Inscribed - “Personalized”
ISP - Inscribed Signed Photograph
LS - Letter Signed
SP - Signed Photograph
TLS - Typed Letter Signed
Lengthy ALS in Dutch, signed “Henk. Casimir,” four pages both sides, 8.25 x 11, September 27, 1930. Letter to Dutch-American physicist Samuel A. Goudsmit. In part (translated): "It has become clear to me, especially because of some remarks from Landau, that application of Dirac’s or Pauli’s theory to a light emitting electron (although giving the right order of magnitude for the doublet splitting) just is not very useful. It seems preferable to treat the problem by introducing a current for both orbit and spin. Thus both spin and orbit each give rise to a magnetic field. When writing down the equations one has to take into account that J is a diagonal matrix. But for coupling between S and I no assumption is made. This converges also for S states and then gives the well known result. One can be sure that one simply has to get the same result as with the Dirac theory, if one neglects relativity effects.”

He continues with an entertaining account of an automobile trip in the western United States, as well as news about his fellow members at the Niels Bohr Institute in Copenhagen: “Here we have Gamow, Rosenfeld and Landau. Landau, a young Russian, is astoundingly smart. Grossly unmannered but very entertaining. Also Bohr likes him very much…Of course we have again some pain in the neck assignments. A Faraday lecture which has to be written is the most urgent. Tomorrow Bohr and I will escape and see if we can get it done.” In fine condition, with trivial paper loss to the top edge of the last page.

A significant scientific letter in which Casimir discusses the Dirac equation involving spin value, developed by Paul Dirac in 1928, which was the first theory to account fully for special relativity in the context of quantum mechanics. Wolfgang Pauli had formulated a similar equation in 1927, which is also referenced here. Casimir developed what is today known as the ‘Casimir trick’ for simplifying calculations with the Dirac equation. Additionally, Casimir mentions legendary fellow physicists Niels Bohr, George Gamow, Lev Landau, and Leon Rosenfeld. As Casimir’s scientific letters are very scarce, this long and detailed example is of the utmost desirability.