REMEMBER the awe-inspiring ruler of the Emerald City who turned out to have manufactured his aura of greatness through ingenious illusions? A similar fate could, just could, be about to befall the father of quantum theory, physicist Niels Bohr.
Bohr famously remarked that those who are not shocked by quantum theory have not understood it. His view of the true nature of the quantum world was that it is unknowable. Although our experiments let us see it as a place filled with waves or particles, these, said Bohr, are mere manifestations of something deeper, beyond the limits of scientific inquiry.
Now a physicist called Shahriar Afshar says Bohr鈥檚 central assertion about quantum theory is wrong 鈥� and he has done an experiment to prove it (see 鈥淨uantum rebel鈥�). Afshar鈥檚 target is Bohr鈥檚 鈥減rinciple of complementarity鈥�. This says that quantum things can be regarded as waves or particles but never as both at once. Einstein challenged this as a fudge that explains nothing, but never succeeded in disproving it, and Bohr鈥檚 strange view of reality has become the orthodox interpretation of quantum theory.
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Many physicists have tested complementarity and found that their experiments back it up. But not Afshar鈥檚. Although his result has yet to be verified, his work is to be applauded. The orthodox view of the quantum world has long been accepted without question, despite the strange claims of its high priests: the elevated status of measurement as a special event that destroys wave-like behaviour; the phantasmagorical 鈥渕any worlds鈥� interpretation, in which quantum things are able to exhibit multiple behaviours because they inhabit an infinite number of separate universes; even a scheme in which waves transfer information at speeds greater than the speed of light.
The Nobel laureate Richard Feynman is much quoted as saying that quantum theory is simply beyond explanation. But science increases our understanding by moving from theory to experiment, and subjecting both to open scrutiny. And then there is Occam鈥檚 razor, the idea that where there are several explanations of any phenomenon, the simplest is the one is to go for. In our interpretations of quantum theory, these principles seem to have been lost along the way.
Whatever the consensus on Afshar鈥檚 experiment, it certainly follows the best scientific tradition: exploring mysteries, not obscuring them. And who knows what the eventual outcome might be? After all, if Toto had never run behind the curtain, Dorothy might never have got home. And how would she then have noticed the resemblance between the Wizard of Oz and Professor Marvel, the manipulative Kansas showman?
