American Physical Society Racah Institute of Physics Workshop

American Physical Society Racah Institute of Physics Workshop Friction in Physics and Society “Little Jerusalem”, The Ticho house (12. 12 @ 12. 12)

A mistake of a Genius (An example of mixed friction – both in physics and society) To the 90 th anniversary of two famous Nobel prizes in Physics Amusia M. Ya. The Hebrew University, Jerusalem

The Nobel Prize in Physics 1921 "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect" Albert Einstein Germany and Switzerland Kaiser-Wilhelm-Institut (now Max-Planck. Institut) für Physik Berlin, Germany

Albert Einstein received his Nobel Prize one year later, in 1922. During the selection process in 1921, the Nobel Committee for Physics decided that none of the year’s nominations met the criteria as outlined in the will of Alfred Nobel. According to the Nobel Foundation's statutes, the Nobel Prize can in such a case be reserved until the following year, and this statute was then applied. Albert Einstein therefore received his Nobel Prize for 1921 one year later, in 1922.

The Nobel Prize in Physics 1922 "for his services in the investigation of the structure of atoms and of the radiation emanating from them" Niels Henrik David Bohr Denmark Copenhagen University, Copenhagen, Denmark

Awarded equations • Einstein’s , 1905 “On a Heuristic Viewpoint Concerning the Production and Transportation of Light” , Annalen der Physik 17 (6), p. 132– 148 • Bohr’s, 1913 “On the Constitution of Atoms and Molecules”, Philosophical Magazine 26 (1), p. 476. Today’s view: energy conservation low in discrete and continuous spectra

Was “Photoeffect” almost trivial for Einstein, generally accepted by public and thus awarding this work was a sort of a compromise? Not at all!

• • First Verifications of Einstein’s equation Energy conservation – R. Millikan, 1915 Momentum conservation – A. Compton, 1919 Both had non-Einsteinian Interpretation, based on theories of J. J. Thomson, A. Sommerfeld 1910 -1913 • Strong opposition of N. Bohr

Acceptance / non-acceptance “That he has occasionally speculated too far (for example, his hypothesis concerning light quanta), should not be held against him since he who takes no such risks will not be able to make really novel contributions to science” Planck, Nernst, Rubens, Warburg, 12 June 1913, from: Nomination to the Prussian Academy of sciences membership

From Bohr’s Nobel Lecture (1): Einstein was led to the formulation of the so-called "hypothesis of light-quanta", according to which the radiant energy, in contradiction to Maxwell’s electromagnetic theory of light, would not be propagated as electromagnetic waves, but rather as concrete light atoms, each with an energy equal to that of a quantum of radiation. This concept led Einstein to his well-known theory of the photoelectric effect. This phenomenon, which had been entirely unexplainable on the classical theory, was thereby placed in a quite different light, and the predictions of Einstein’s theory have received such exact experimental confirmation in recent years, that perhaps the most exact determination of Planck’s constant is afforded by measurements on the photoelectric effect.

From Bohr’s Nobel Lecture (2): This phenomenon, which had been entirely unexplainable on the classical theory, was thereby placed in a quite different light, and the predictions of Einstein’s theory have received such exact experimental confirmation in recent years, that perhaps the most exact determination of Planck’s constant is afforded by measurements on the photoelectric effect.

From Bohr’s Nobel lecture (3): In spite of its heuristic value, however, the hypothesis of light-quanta, which is quite irreconcilable with so-called interference phenomena, is not able to throw light on the nature of radiation. I need only recall that these interference phenomena constitute our only means of investigating the properties of radiation and therefore of assigning any closer meaning to the frequency which in Einstein’s theory fixes the magnitude of the light-quantum.

Battle of Giants I “This is my most revolutionary paper” A Einstein’s (no ether, yes quanta, duality) One should compare to presented above quotation: “In spite of heuristic value, however, the hypotheses of light quanta, which is quite irreconcilable with socalled interference phenomena, is not able to throw light on the nature of radiation”, Bohr’s Nobel lecture, 1922

Battle of Giants II 1. Frequency in Photoeffect equations comes not from quantum picture but from wave interference 2. Einstein laws are complimentary to classical picture and are valid on the average N. Bohr, H. Kramers, and J. Slater, Quantum Theory of Radiation, Phil. Mag. , 47, 785, 1924

Battle of Giants: The End • Confirmation of Photoeffect: Millikan, 1916 • Photon energy-momentum conservation: Coincidence experiment in Compton effect W. Bothe and H. Geiger, 1925 A. Compton and A. Simon, 1925 … W. Gross and N. Ramsay, 1950!

Aftershock 1 • Bohr tried to apply his ideas on violation of energy conservation in elementary processes to explain continuous spectrum of electrons in -decay (1930) “n → p + e” • Pauli in 1930 suggested a new particle, neutral and very light particle v, that explains the controversy • “ n → p + e + v”

Aftershock 2 • Pauli was correct. The conservation in microscopic processes has been saved. A new particle was predicted and later detected • Pauli in 1930 suggested a new particle, neutral and very light particle v, that explains the controversy • “ n → p + e + v”

Aftershock 3 Pauli’s letter to “radioactivists” (1930): (1930) I admit that my remedy may appear to have a small a priori probability because neutrons, if they exist, would probably have long ago been seen. However, only those who wager can win, and the seriousness of the situation of the continuous -spectrum can be made clear by the saying of my honored predecessor in office, Mr. Debye, "One does best not to think about that at all, like the new taxes. "

Concluding remarks • Einstein and Maxwell pictures peacefully coexist, in respective domains • Conservation laws are the fundament of our understanding of physical processes at any size of the objects • Mistakes of a genius are by itself a great achievement that was confirmed by the Bohr. Einstein second, well-known debate in the thirties, where Bohr was the winner • Thank you very much for patience and attention

PS: Einstein on Quantum mechanics 1 There is no doubt that quantum mechanics has seized hold of a beautiful element of truth and that it will be a touchstone for a future theoretical basis in that it must be deducible as a limiting case from that basis just as electrostatics is deducible from the Maxwell equations of the electromagnetic field or as thermodynamics is deducible from statistical mechanics.

PS: Einstein on Quantum mechanics 2 However, I do not believe that quantum mechanics will be the starting point in the search for this basis, just as one cannot arrive at the foundations of mechanics from thermodynamics or statistical mechanics. Journal of the Franklin Institute, 221, 313, 1936 The result of Einstein - Bohr lifelong debate: 1: 1