From: John Clark (jonkc@worldnet.att.net)
Date: Tue Aug 24 1999 - 10:58:56 MDT
Anders Sandberg <asa@nada.kth.se>
>Heisenberg only showed that measurement uncertainties will
>always be larger than a certain level, essentially
>placing a limit on how well we (or anything else) can distinguish
>quantum states.
But it's much deeper than just a measurement problem. Take the old
2 slit experiment for example, it's not that the photon goes through
one slit and we just don't know which one, it must go through the left
slit only, and the right slit only, and both slits, and no slit at all, and it
must do all these things at the same time.
Shine a light on 2 closely spaced slits and it will produce a complex
interference pattern on a film, even if the light beam is so weak the
photons (or any other particle) are sent out one at a time. If a particle
goes through one slit it wouldn't seem to matter if the other slit,
the one it didn't go though, was there or not, but it does.
Even stranger, place a polarizing filter set at 0 degrees over one slit, and
one set at 90 degrees over the other, the interference pattern disappears.
Now place a third filter set at 45 degrees one inch in front of the film and
10 light years from the slits. The interference pattern comes back, even
though you didn't decide to put the filter in front of the film until 10 years
after the photons passed the slits! Heisenberg's Uncertainty Principle does
not enter into any of this. Quantum Mechanics may or may not be a good
idea but one thing is certain, it's the law.
John K Clark jonkc@att.net
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