Source: An Invitation to Quantum Field Theory (2012), Ch. 1 : Why Do We Need Quantum Field Theory After All?
“One can see clearly some ambivalence in Dirac's attitudes… On the one hand, he has repeated many, many times his conviction that beauty in the fundamental equations of physics has priority… On the other hand… we see Dirac deeply involved with approximate calculations whose only purpose was to obtain an answer which the experimenters could rely upon.”
R. H. Dalitz, Another side to Paul Dirac, in Paul Adrien Maurice Dirac (Cambridge University, Cambridge, 1987) Chapter 10.
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Richard Dalitz 3
Australian physicist 1925–2006Related quotes

W. E. Lamb, Sequential measurements in quantum mechanics, in Quantum Measurements and Chaos, E. R. Pike and S. Sarkar, eds. (Plenum, New York, 1987) pp. 183-193.

“Neither Dirac nor von Neumann discussed his measurements in physical terms.”
W. E. Lamb, Classical measurements on a quantum mechanical system, Nuclear Phys. B 6, 197-201 (1989).
A Text-Book of Thermodynamics with Special Reference to Chemistry (1913)

in Introduction to Lasers, [F. J. Duarte, Tunable Laser Optics, Elsevier Academic, 2003, 0-12-222696-8, 3]

Liquidation (2003)
Context: Thereafter, the scenes had succeeded one another, turn and turn about, in the drama as in reality, to the point that, in the end, Kingbitter did not know what to admire more: the author's-his dead friend's-crystal-clear foresight or his own, so to say, remorseful determination to identify with his prescribed role and stick to the story.
Nowadays, though, with the lapse of nine years, Kingbitter was interested in something else. His story had reached an end, but he himself was still here, posing a problem for which he more and more put off finding a solution. He would either have to carry on his story, which had proved impossible, or else start a new story, which had proved equally impossible. Kingbitter undoubtedly could see solutions to hand, both better ones and worse; indeed, if he reflected more deeply, solutions were all he could see, rather than lives.

Source: Decent and Indecent: Our Personal and Political Behavior (1970), p. 13

in Introduction to Lasers, [F. J. Duarte, Tunable Laser Optics, Elsevier Academic, 2003, 0-12-222696-8, 3] (while discussing The Feynman Lectures on Physics).