Alexander Afriat Boeken

"Paradox" conjures up arrows and tortoises. But it has a speculative, gedanken no one would dream of really conjuring up Achilles to confirm that he catches the tortoise. The paradox of Einstein, Podolsky, and Rosen, however, is capable of empirical test. Attempted experimental resolutions have involved photons, but these are not detected often enough to settle the matter. Kaons are easier to detect and will soon be used to discriminate between quantum mechanics and local realism. The existence ofan objective physical reality,which had disappeared behind the impressive formalism of quantum mechanics, was originally intended to be the central issue of the paradox; locality, like the mathematics used, was just assumed to hold. Quantum mechanics, with its incompatible measurements, was born rather by chance in an atmosphere of great positivistic zeal, in which only the obviously measurable had scientific respectability. Speculation about occult "unobservable" quantities was viewed as vacuous metaphysics, which should surely form no part of a mature scientific attitude. Soon the "unmeasurable, " once only disreputable, vanished altogether. One had first been told not to worry about it; then, as dogma got more carefully defined, one was assured that the unobserved was just not there. This made it easier not to think about it and to avoid hazardous metaphysical temptation.

De quoi est fait le monde ? La question peut bien se poser mais les reponses ont ete etonnantes: d'eau, de corpuscules (eventuellement crochus), d'air, de feu, d'ondes, de terre, d'effluves, de champs, d'energie et ainsi de suite. La liste est longue (on n'a oublie que le caoutchouc). Aujourd'hui les realistes structurels nous apprennent meme que le monde serait constitue de structures mathematiques, celles notamment qui figurent dans nos meilleures theories physiques. Et ces dernieres incluraient, pour en venir au sujet de ce livre, des theories de jauge, dont les structures assumeraient ainsi une valeur ontique. Le monde serait donc compose dans un sens auquel il faut eventuellement s'habituer de ces memes structures. Mais ces structures, d'ou viennent-elles ? De toutes pieces de l'experience ? Son apport est certes important, mais il y a autre chose. Preface de Jean-Jacques Sczceciniarz