This year’s Nobel Prize in Physics (2022) goes to Alain Aspect, John Clauser, and Anton Zeilinger, who performed groundbreaking experiments in the field of quantum research. Both the emergence and the role of quantum mechanics within the last hundred years have been a central research topic of the Max Planck Institute for the History of Science (MPIWG) for some time. That quantum mechanics would bring with it a radically new view of the world was already apparent during its development (1925–1927). However, the extent to which it differed from nineteenth-century classical physics only gradually became apparent—a process that was investigated in Department I of the MPIWG within a large-scale project on the history and foundations of quantum mechanics (duration 2006–2012).
It became apparent early on that the intervention of researchers (in the sense of experimental measurement) was taking on a new and central role in the microscopic world of quantum mechanics. The influence of measurement on the quantum object under investigation (e.g., an atom or a particle of light) could no longer be ignored. This discovery of subjective coloration was diametrically opposed to a classical conception in which the scientific experiment was understood as an objective observation “from outside.”
Following the predictions of quantum mechanics, Erwin Schrödinger then found that the influence of the measurement was not limited to the immediate object of investigation, but rather extended to more distant quantum objects not directly affected by the measurement. He described this surprising remote effect with the term “entanglement.”
The Nobel Prize in Physics has now been awarded for the scientific discovery that proved the existence of this “entanglement” in the exact form predicted by quantum mechanics. Numerous historical studies of this development can be found in the Oxford Handbook on the History of Quantum Interpretations (2022, edited by Olival Freire Jr.)—many of them by current as well as former MPIWG researchers.
This evidence is relevant for two reasons: First, it has a practical dimension, namely, whether in the future such entangled states might also find use as a resource in new quantum technologies (e.g., quantum computers); and second, it sheds new light on the question of whether quantum mechanics is a fundamental knowledge of the world at all. Einstein, for example, did not believe it was. He called entanglement a “spooky action at a distance” and sought a “unified field theory” that would describe the microscopic world even without such a spook. Although his attempt failed, it nonetheless became the model for the search for the so-called “final theory”—and as such it is being studied by MPIWG researcher Bernadette Lessel in the Max Planck Research Group “Historical Epistemology of the Final Theory Program.” Lessel also organized the 2019 “History for Physics” conference in Vienna—Anton Zeilinger’s hometown—where both historians and physicists could exchange ideas on the fundamental questions of quantum mechanics.
More recent attempts to find the final theory invoked Einstein's vision but understood quantum mechanics as a given and not to be doubted (see Blum 2019, Heisenberg's 1958 Weltformel and the Roots of Postempirical Physics; also Blum/Furlan 2022, How John Wheeler lost his Faith in the Law). The experimental results of the 2022 Nobel Prize winners in physics then made such a fundamental acceptance of quantum mechanics virtually without alternative.