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Re: Particle Position



On Tue, 11 May 1999, John Denker wrote:

1) To my way of thinking, there is no such thing as a particle and no such
thing as a wave --- there is only stuff. The terms "wave" and "particle"
are inherited from 19th-century physics. They apply, if at all, to certain
asymptotic situations, in which case we can perhaps say "this stuff is
acting like a particle, approximately" or "this stuff is acting like a
wave, approximately".

The terms "particle" and "wave" are certainly loaded and, therefore,
problematic, but I don't think substituting "stuff" helps make matters
much clearer. It seems to me that the primary lesson of quantum physics
is that measurements are everything. We know the world *exclusively*
through measurements and measurements happen *only* when something--even
if "only" our state of awareness--"changes." We are playing at
metaphysics when we interpret the patterns that we see in our measurements
as implying specific underlying physical "things" like particles, waves,
blue whales, or any other kind of "stuff."

This is not at *all* to denigrate the important role of these metaphysical
games in doing physics. If we didn't play them, our measurements would
simply comprise volumes of sterile facts. The patterns that we find in
collections of measurements prompt us to exercise our imaginations and
create physical models. The physical models, in turn, help us to
formulate complementary mathematical models that have quantitatively
precise predictive power. Once the mathematical models are created, the
physical models are somewhat superfluous; if we can predict the result of
any measurement, we have done all that could ever reasonably be asked.
(And the fact that quantum physics seems to say that measurement
prediction necessarily involves probabilities instead of certainties
doesn't fundamentally alter this conclusion.)

Having said all of the above, it is precisely the metaphysical games that
(IMO) makes the study of physics *the* most exciting and satisfying human
undertaking. Nature didn't have to organize itself in such a way that our
measurements show any patterns whatsoever. The fact that it does and the
fact that we all see the same patterns, seems strongly to imply the
existence of a "reality" behind our measurements. The exquisite structure
of those patterns implies a similarly exquisite reality. It is the
neverending quest for an understanding of that exquisite--if only
implied--reality that keeps us interested.

John
----------------------------------------------------------
A. John Mallinckrodt http://www.csupomona.edu/~ajm
Professor of Physics mailto:ajm@csupomona.edu
Physics Department voice:909-869-4054
Cal Poly Pomona fax:909-869-5090
Pomona, CA 91768-4031 office:Building 8, Room 223