From the necessary to the possible: the genesis of the spin-statistics theorem

Diagnosing disagreements: The authentication of the positron 1931–1934

“…For reviews on the origins of Dirac's equation see [29] and [30]. 10 For an early history of the Spin-Statistics Theorem see [31] and [32]. 11 For example, Moyer [34] notes that " Two metaphors -magic and sickness -recur in recollections of early reactions to Dirac's theory.…”

“…Third, Blackett's and Occhialini's interpretation was tied to Dirac's hole theory, of which Bohr thought that it was "not a theory that one can believe in" 33 for a variety of reasons (i.e., formalism, mea- 31 In a footnote to a letter to Peierls, dated May 22, 1933, Pauli reports that "[w]hen I saw him in March, he [Bohr] absolutely rejected the positive electron and thought that Blackett had just produced some 'pathological photographs'" ( [52], p. 468). 32 Rudolf Peierls recollects the same attitude, noting that "[e]even after the discovery of the positron, which behaved exactly as Dirac had predicted a hole would behave, Bohr was cautious and urged that it should not be taken for granted that this was the right interpretation of the new particle" ( [53], p. 58). 33 Bohr's remark as reported by Rosenfled in his interview with Oskar Klein, see [47].…”

“…It is worth noting that despite an intense interest in Dirac's equation and the hole theory, Pauli had misgivings about both from the beginning. 43 As Blum notes, "[w]hat bothered him most was the fact that it appeared to place the asymmetry between positive and negative charge in the initial conditions (i.e., the occupied negative energy states) rather than in the physical laws [...]" ( [32], p. 550). From Pauli' viewpoint, potential violations to conservation laws in β-decay also spoke against Dirac's positron, as did the formalism of the hole theory, for which Pauli used the "deprecatory term 'subtraction physics'" ( [58]).…”

“…Pauli's views exerted a certain influence in the community, since physicists "always benefitted by Pauli's comments even if disagreement could temporarily prevail", but as Bohr notes, "if he felt he had to change his views, he admitted it most gracefully, and accordingly it was a great comfort when 43 Blum, in particular, stresses this point in connection to symmetry violations: "The most prominent critic of the Dirac equation, and of hole theory in particular, was Pauli. He was unsatisfied with hole theory from the start" ( [32], p. 550). 44 Pauli, in collaboration with his assistant at the time, Victor Weisskopf, wrote an 'anti-Dirac' paper [59], which was meant to avoid Dirac's 'subtraction physics'.…”

“…Nor as regards the applicability of Dirac's theory to this problem, I feel certain, or more correctly, I doubt it, at least for the moment (cited in [4], p. 76). 32 Bohr continued to be suspicious of the identification of the experimental particle with the Dirac particle throughout 1933. His attitude, far from being mysterious, was due to a number of factors that could not easily be put into a consistent picture.…”