From: L' Ermit (lhermit@hotmail.com)
Date: Mon Jan 28 2002 - 01:10:16 MST
<snip>
[Joe Dees 2*] This may apply on the quantum level, but it obviously does not
apply on the macro level at which i destroyed my sand-painting. Heisenberg's
Uncertainty principle states that the information we may simultaneously gain
about a particle's position and momentum cannot exceed a certain multiple of
the terms. More momentum info. means less position info., and verse-vice-a,
and this has to do with the empirical limits to which matter/energy can be
pushed to investigate itself. It was not, as you stated above, about spin,
which does not change, but
about position and momentum, which are both changed by the influence of the
measuring light. I see no problem in ascertaining spin and then performing
measurements that give one momentum and/or positional info, with the
heisenbergian constraints that these will be different than they were before
the spin check, and can not be measured to a degree of precision beyond the
Heisenberg quotient.
<snap>
[Hermit 2] The momentum of a particle is a function of the velocity and spin
(color) and it definitely applies even when we deal with such mundane issues
as high speed fiber-optic links and indeed we rely upon it when we use
quantum encryption to secure information from interception on such links. We
[i]know[/i] that particles evaporate to prevent us from learning this degree
of information about them - for a trivial and well-known example refer e.g.
Bell's [aka Cambridge] experiment.
[Hermit 2] Spin, as you (correctly) observed, does not change. Thus having
determined the spin, we cannot discover the location (within limits) - at
any time thereafter - for that particle. If the information about the
knowledge of the spin were not preserved, there would be no way for this to
be the case.
Regards
Hermit
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This archive was generated by hypermail 2.1.5 : Wed Sep 25 2002 - 13:28:41 MDT