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Science Friday
Quantum Leaps
Review by Tom Siegfried
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Quantum Leaps by Jeremy Bernstein

Quantum mechanics is famous for making nature much more complicated than it seems. Within quantum math exist countless possible realities, of which human observers generally perceive only one. Books trying to explain these bizarre multiple existences are about as numerous as the multiple realities themselves.

Adding one more such book to the library already in print may be overkill, but Bernstein’s contribution is nevertheless welcome. A physicist-turned-prolific-writer, he is among the most engaging and thoughtful of quantum explainers, and Quantum Leaps provides one of the best concise guides available to what the fuss is all about.

In quasiautobiographical fashion, Bernstein describes his own struggle to grasp quantum weirdness, focusing on the work of physicist John Bell. In the 1960s, Bell conceived the insight that allowed quantum weirdness to be truly tested — that is, to distinguish the standard but crazy quantum physics interpretation from Newtonian sanity.

Quantum theory insists that the future is not precisely determined by the present. Naysayers sought to restore determinism with “hidden variables” that secretly did determine the future. Bell showed how to test that idea with experiments on a bizarre long-distance linkage, or entanglement, of certain particle properties. When the tests were ultimately done, weirdness won.

Bernstein recounts how Bell’s work brought quantum physics into the mainstream of popular culture, especially in the form of some far-out books and films connecting it to Eastern mysticism and phenomena sounding suspiciously supernatural. Bernstein politely dismisses such works as “amiable nonsense,” which they are. Fortunately for those who prefer the real quantum story, Bernstein’s book is simply amiable.

Harvard Univ. Press, 2009, 213 p., $18.95.


Comments 3
  • Bell's tests implicitly take for granted that entangled electrons or entangled emitted photons are point-like particles. If it is not the case, if they are part of global wave-like structure whose states can be measured and perceived differently according to the position and angle of the measuring apparatus relative to the emitting source, Bell's tests are not valid. The two measured "particles" are "entangled" but not in the sense of spooky action at a distance but as two measurements linked by the emitting phenomenon.

    Even Bell himself once said that impossibility proofs like the one he put forward often only prove our lack of imagination and our inability to expound our implicit hidden assumptions.

    See "The ghosts haunting modern physics" at [Link was removed] for further comments on modern quantum physics.
    Bertrand Ducharme Bertrand Ducharme
    Nov. 21, 2009 at 3:37pm
  • In response to the comment by B. Ducharme, I fail to see how any notion of "global wave-like structures" could negate the non-local coupling of sequential measurements which are found to be correlated regardless of the order in which said measurements are performed.
    Ralph Dratman Ralph Dratman
    Nov. 21, 2009 at 9:06pm
  • Regardless of the order of the two measurements, the first and the second measurement could depend on the correlation of the two set of waves generated by the emitting phenomenon. This global wave structure does not negate the "non-local" coupling of sequential measurements. The "non-local" coupling is already embedded in the wave structure equation generated by the emitting phenomenon. The 2 measurements are not therefore statistically independant events.
    Bertrand Ducharme Bertrand Ducharme
    Nov. 22, 2009 at 3:16am
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