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FEYNMAN, R.; TOMONAGA, S.; SCHWINGER, J.; BETHE, H. et al. Milestones in Quantum Electrodynamics (QED) An extensive collection of TWENTY-FOUR major works from the ‘golden age’ of quantum electrodynamics, including all the crucial papers by Feynman, Tomonaga and Schwinger which gained them the Nobel Prize for Physics in 1965. A rare and remarkable collection documenting the development of one of the most important advancements in modern science.Contained in:
Quantum electrodynamics (QED) is the quantum theory of the interactions between electrically charged particles and the electromagnetic field (between electrons, positrons and photons, for example). It has been called “the jewel of physics” because of the extreme accuracy of its predictions: for example, the value of the magnetic moment of the electron calculated from QED agrees with the measured value to within a few parts in 100,000,000,000. QED was born in 1928, with Dirac’s paper “The quantum theory of the emission and absorption of radiation”, which showed that electromagnetic radiation, contained in an enclosure, is equivalent to an infinite number of harmonic oscillators, and used the standard methods of quantum mechanics to quantize these oscillators. Although a major advance, this theory, and its development over the next decade by Heisenberg, Jordan, Pauli and others, encountered numerous difficulties: it predicted an infinite self-energy for the electron [1], and several other such ‘divergences’. The spur to further progress came from experiment. At the Shelter Island conference in June 1947, Willis Lamb [7] reported that the 22S1/2 level of hydrogen lies above the 22P 1/2 level by about 1000 MHz, a result in conflict with the Dirac-Heisenberg-Pauli theory. This has been called ‘one of the most important atomic physics experiments ever published’ (The Physical Review: The First Hundred Years, p. 93). It was accepted by the participants that this result must be interpreted in terms of radiative corrections to the leading order predictions of QED. This was made concrete almost immediately by Hans Bethe, who carried out a calculation [8] of the ‘Lamb shift’ on the train home from the conference: although this was somewhat rough-and-ready it gave a result in good agreement with experiment, and was clearly on the right track. A second experimental result which demonstrated the need for change was that of Polykarp Kusch of the magnetic moment of the electron [9]. Julian Schwinger [10] used a technique similar to Bethe’s to calculate this anomalous magnetic moment, and again found results in excellent agreement with experiment. The work of Bethe and Schwinger showed that the parameters of mass and charge associated with the electron in the formalism of QED are not the quantities measured under ordinary conditions: a process of ‘renormalization’ must be carried out in which the initial parameters are eliminated in favor of those with immediate physical significance. The problem was: how to carry out this renormalization in a way consistent with the requirement that the theory is relativistically invariant? The solution was provided independently by Richard Feynman, Schwinger and Sin-Itiro Tomonaga.. The methods of Feynman and Schwinger were reported at the Pocono conference in March 1948. Schwinger’s method [15, 17, 18, 22] was highly technical, while Feynman’s was diagrammatic, using his now-famous ‘Feynman diagrams’ [21]. Feynman’s method was highly efficient, yielding results with a fraction of the effort required by Schwinger’s techniques, but it was not clear to most people why it worked (Feynman finally provided a rigorous justification two years later [24]). A few weeks after the Pocono conference, Robert Oppenheimer received a letter from Tomonaga in which he described his own solution [3-6, 11-14], which turned out to be very similar to Schwinger’s. Freeman Dyson [16] showed that the Feynman approach is equivalent to that of Schwinger-Tomonaga. He showed further [19] that only three quantities need to be renormalized, the mass, charge and wave function. Once this carried out every term in the perturbative expansion in powers of the coupling constant is finite (nowadays this is expressed by saying that QED is ‘renormalizable’). Ward [23] showed that the so-called ‘ultraviolet divergences’ all disappear after renormalization. With this work, the ‘golden age’ of QED came to an end. Kusch and Lamb won the Nobel Prize in physics in 1955 for the experimental work which laid the foundation of the modern theory of QED, and Feynman, Schwinger and Tomonaga shared the Prize of 1965 for their theoretical work on QED. The Physical Review: The First Hundred Years, American Institute of Physics, 1999; J. Schwinger, Selected papers on Quantum Electrodynamics, Dover,1958; S. Schweber, QED and the Men Who Made IT, Princeton, 1994.
1.WEISSKOPF, V. S. On the
self-energy and the electromagnetic field of the electron, Physical
Review, Vol. 56, No. 1 (1939), pp. 72-85
Price for the collection: $16,000. |
