Re: Quantum Rebel

From: Jesse Mazer <>
Date: Wed, 28 Jul 2004 16:35:28 -0400

Actually, looking at the diagram and explanation of the experiment posted at I think Saibal Mitra
and the sci.physics.research poster I quoted may have misunderstood what
happened in this experiment. I may have misunderstood, but it sounded as if
both were arguing that the finite width of the wires could erase some of the
which-path information and explain why you'd see interference at the final
detectors. But the diagram seems to say that *no* interference was found at
the detectors----the interference Afshar is talking about was just in the
fact that no photons were scattering against the wires because they were all
placed in the interference valleys. So the idea seems to be that
interference is the explanation for why no photons scatter against the
wires, but the focusing lens behind the wires makes sure that photons from
the left slit always go to the left detector and the photons from the right
slit always go to the right detector--this is the "violation of
complementarity", that the photons behave like a wave in avoiding the wires
but behave like particles when arriving at the detectors. I'm not sure that
the notion of "complementarity" has ever been sufficiently well-defined to
say that this experiment violates it though, and in any case, as long as the
results of the experiment match the predictions made by the standard theory
of quantum mechanics, it cannot be taken as a disproof of the Everett
interpretation, since the basic idea of the Everett interpretation is to
keep the standard rules for wavefunction evolution but just to drop the
"collapse" idea (the projection postulate).

Received on Wed Jul 28 2004 - 16:39:38 PDT

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