“When investigating theories at the tiniest conceivable scales in nature, almost all researchers today revert to the quantum language, accepting the verdict from the Copenhagen doctrine that the only way to describe what is going on will always involve states in HIlbert space, controlled by operator equations.”
The Cellular Automaton Interpretation of Quantum Mechanics, 21 December 2015, arXiv:1405.1548v3 https://arxiv.org/abs/1405.1548,
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Gerardus 't Hooft 8
Dutch theoretical physicist and Nobel Prize winner 1946Related quotes

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Interview in The Hindu (2013)
Context: The improved understanding of the equations of hydrodynamics is general in nature; it applies to all quantum field theories, including those like quantum chromodynamics that are of interest to real world experiments. I think this is a good (though minor) example of the impact of string theory on experiments. At our current stage of understanding of string theory, we can effectively do calculations only in particularly simple — particularly symmetric — theories. But we are able to analyse these theories very completely; do the calculations completely correctly. We can then use these calculations to test various general predictions about the behaviour of all quantum field theories. These expectations sometimes turn out to be incorrect. With the string calculations to guide you can then correct these predictions. The corrected general expectations then apply to all quantum field theories, not just those very symmetric ones that string theory is able to analyse in detail.
Grinker (1976) in General systems. Vol.19, p. 57

in Physical Process and Physical Law, in an edition by [Timothy E. Eastman, Hank Keeton, Physics and Whitehead: quantum, process, and experience, SUNY Press, 2004, 0791459136, 181]

page 19 of [2002, A brief course in spontaneous symmetry breaking ii. modern times: The BEH mechanism, arXiv preprint hep-th/0203097, https://arxiv.org/pdf/hep-th/0203097.pdf]