Alain Aspect, <i>Einstein and the Quantum Revolutions</i> Chicago: University of Chicago Press, 2024. Pp. 117. ISBN 978-0-226-83201-2. $16.00 (cloth).

The Great Voices in Research, presenting the work of CNRS gold medalists.The book offers a bird's-eye view of the development of quantum physics.Written for a general audience, it is similar to Carlo Rovelli's short books on physics; at the same time, it is relevant for historians of science for its unique vision of the history of quantum physics from a cutting-edge Nobel Prize-winning experimental, rather than theoretical, physicist.By the second sentence, in which the quantum revolution is equated to the industrial one, it is clear that we are reading an experimentalist's views on quantum mechanics.Aspect then nods to the Baconian goal of changing society through scientific theories.But his vision goes further: according to Aspect, there were two quantum revolutions.Historians have focused on the first, of the early twentieth century.The second is equally acute as a theoretical development, but potentially more important in its applications.It started with a focus on one of the trickiest quantum puzzles -quantum entanglementsbut steadily led to groundbreaking experimental work, including Aspect's, and to quantum computing.The crux of the book's concise analysis is its identification of a feedback loop between quantum theory, experiments and applications, all of which have probed the limits of the physical world.Aspect narrates the first quantum revolution in a conventional way, taking a compressed walk through emergence of quantum theory and quantum mechanics, from Planck's considerations of black-body radiation and his unconventional idea of handling it via discrete energy exchange of radiation, to Albert Einstein's idea of constitutive radiation packets (photons) and the dependence of their energy on frequency rather than intensity, to wave-particle duality and the formal (matrix and wave) duality that captured it, to Dirac's formal unification of theory in the 1930s.What stands out as a theoretically daring insight among many from the first revolution, according to Aspect, is Einstein's vision of radiation composed of discrete units, since the insight went against the entire nineteenth-century construction of radiation as a continuous-wave phenomenon.A brief historical account of wave-particle duality is followed by discussions of Aspect's experiments with Philippe Grangier testing it using individual photons.The beam splitting produced interference patterns, even when individual photons were emitted from the source.Any doubt that wave-particle duality would hold at the level of individual particles vanished.The experimentalist's perceived choice between whether the apparatus