From: hal@finney.org
Date: Thu Oct 11 2001 - 10:30:00 MDT
Scerir writes:
> Most physicists would say that the electron observed in Paris
> at T_0 was *already* there. And that those 2 w.f. represented
> just our *knowledge* prior to that observation.
I don't believe this is true, although I'm not sure about the exact
details of this particular experiment. In the case of separated particles
with correlated spins, most physicists today would *not* say that the
particles actually had well-defined spins but that the wave function
represented our lack of knowledge of those spins prior to observation.
The reason they don't say this is because you can in principle bring the
particles back together and show interference effects which would not be
possible if they had well defined spins. If physicists had adopted the
stance you describe, they would be forced to say that once the boxes were
brought near each other the particles had lost their well-defined spins
(or positions), which is absurd.
There is a fundamental difference between these quantum effects and the
classical phenomenon of two boxes only one of which contains a particle.
With the quantum case it is clear that there is no well-defined state
until the measurement is done. In the classical case this is not true.
It confuses the issue to suggest that these two situations are similar.
Hal
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