Heisenberg-Majorana nuclear forces

In March 1932 James Chadwick announced the discovery of the neutron, after which Majorana revealed to his friends and colleagues in Rome that he had built a theory of light nuclei based on the quantum concept of exchange forces. Although encouraged by Fermi to go public with his results, Majorana’s hypercritical judgement prevented him from doing so. True to style, his work was not recognized until a few months later when it was independently elaborated by Werner Heisenberg. According to Heisenberg, the underlying nuclear forces should be interpreted in terms of nucleons exchanging spinless electrons, implicitly assuming that the neutron was practically formed by a proton and an electron. Majorana immediately realized this defect of the Heisenberg’s theory. Instead, in Majorana’s view, the neutron was pictured as a “neutral proton”, as it effectively is, and the erroneous experimental consequences of the Heisenberg model were quickly recognized by Heisenberg himself and others.

This fact caused a sensation in the Rome group, and Fermi urged Majorana, successfully, to visit Heisenberg – who would be awarded the 1932 Nobel Prize for Physics at the end of 1933 – in Leipzig for a six-month period in 1933. Here, Majorana’s ability and results [8] largely impressed Heisenberg who later, on several occasions while discussing the “Heisenberg–Majorana” exchange forces, only marginally mentioned his own contribution, whereas annoyingly that of Majorana was pointed out as if Heisenberg knew he was indebted to his young colleague.

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