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Bernard d'Espagnat

Discussion in 'WWII Era Obituaries (non-military service)' started by GRW, Aug 19, 2015.

  1. GRW

    GRW Pillboxologist WW2|ORG Editor

    Oct 26, 2003
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    Stirling, Scotland
    "Bernard d’Espagnat, who has died aged 93, was a French physicist and philosopher of science who in 2009 won the £1 million Templeton Prize, awarded annually to individuals who “affirm life’s spiritual dimension”, for his work on the philosophical implications of quantum mechanics.
    Quantum physics (of which quantum mechanics is a branch) is the study of systems at or below the atomic level: atoms, electrons, protons, and subatomic particles. Unlike the cause-and-effect of our everyday physical world, subatomic particles behave in ways which appear to defy the traditional laws of physics, undermining materialist accounts of the nature of reality. Photons (light particles) for example, spin in many ways, such as “up” or “down,” at the same time. Even more mysteriously, it is only when they are observed that they fix into particular states of spin.
    Quantum theory also predicts a phenomenon known as “entanglement”, whereby tiny particles such as electrons, which have interacted in the past then moved apart, possibly billions of miles apart, will change their polarisation (the oscillation of waves) simultaneously when the property of one of the pair is measured, implying some form of communication between them faster than the speed of light.
    Einstein dismissed such notions as “spooky actions at a distance” and argued that if quantum theory predicted such nonsense, conflicting with the accepted laws of physics, then the theory itself had to be questioned. In 1964, however, at a time when quantum theory was proving its validity across a range of practical applications, a physicist called John Bell returned to the knotty issue of entanglement, showing that quantum theory required entanglement and that the strange connectedness between particles was an inescapable feature of fundamental quantum equations. All that was missing was experimental proof.
    In the early 1970s John Clauser, a researcher at the Lawrence Berkeley National Laboratory, and his colleague, Stuart Freedman, rigged up a contraption to measure quantum entanglement and fired thousands of pairs of particles of light known as photons in opposite directions from the middle of the device toward each of its two ends. At each end was a detector which found precisely the correlation in the polarisation of the twin particles that was predicted by quantum theory.
    D’Espagnat, who had met Clauser and Freedman during a sabbatical in the United States, was the first to point out the philosophical issues underlying the phenomenon of entanglement. In a series of papers and in “The Quantum Theory and Reality,” a widely read 1979 article in Scientific American, d’Espagnat argued that materialist doctrines which claim that the world is made up of objects whose existence is independent of human consciousness, and that objects widely separated in space cannot affect each other simultaneously, is not only in conflict with the predictions of quantum mechanics, but with facts established by experiment.
    Some physicists had doubted the accuracy of Clauser and Freedman’s experiments, but d’Espagnat’s article helped to stimulate more sophisticated experiments by the French physicist Alain Aspect and others, which confirmed Clauser’s results and suggested that d’Espagnat’s philosophical insights might be valid.
    D’Espagnat, a professor at the University of Paris-Sud, coined the term “veiled reality’’ to describe an elusive world beyond what is visible or detectable, which science can only glimpse through study of quantum behaviour and which, he argued, could be compatible with “higher forms of spirituality’’ glimpsed in ordinary life through such experiences as listening to Mozart. Since science cannot reveal anything certain about the nature of being, he concluded, it cannot tell us with certainty what it is not.
    Although most physicists tended to turn their back on the more mystical aspects of his reasoning (d’Espagnat himself denied that quantum science could tell us anything about the existence or otherwise of God), his work represented an important step in the process which led to the development of “quantum information science”, a flourishing field of research combining physics, information science and mathematics.
    The only child of the post-Impressionist painter Georges d’Espagnat, Bernard d’Espagnat was born in Fourmagnac, in southern France, on August 22 1921 and grew up in Paris. His plans to study Mathematics at the École Polytechnique were interrupted by the German occupation of France. Later in the war he was sent to do forced labour in a factory in Vienna, from which he escaped with a friend after six months, making it back to France just a few weeks before the conflict ended."

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