Dear Arne and colleagues,
There is an essential reason, I believe, why nearly all physical
scientists are realists. There would be no physical science without
realism. Perhaps the most fundamental assumption upon which physical
science depends is the conviction that all of us are imbedded in the
same, objective physical reality.
I understand that one cannot prove this deductively, but the inductive
evidence seems, to most of us, to be overwhelming. From the very
beginning of physical science, through to the present, all of our
scientific accomplishments rely on a description of nature that is
observer independent. We’ve incorporated Gallilean relativity into the
fundament of classical physics. All the classical equations of motion
are observer independent. Would there be anything at all left of the
physical sciences if we discarded classical mechanics?
It is exactly the consistency and usefulness of the physical sciences
that argues, irrefutably, I believe, for the validity of the axioms upon
which physical science depends. Statistical mechanics, hydrodynamics,
electrodynamics, and others cannot stand without classical mechanics.
So, we physical scientists must adamantly refuse to concede that because
realism is not deductively derivable, it might not be correct.
I note that Einstein built both his theories of relativity, special and
general, on the postulate of observer independence. Should we throw out
those extraordinarily valuable and consistent theories because we wish
to debate the lack of a deductive argument for realism? I’m sure that
quantum mechanics (which also employs classical mechanics via the
Hamiltonian formalism, Poisson Brackets, etc.) does not imply observer
dependence, though some eminent physicists, like Wigner and von Neumann,
have read it that way.
The accepted understanding of the wavefunction, Psi, was given in the
early 1920s by Max Born. As you know, If we wish to calculate the
probability for each possible measured value of the system we take the
projection of the eigenfunction for that value on the wave function,
then calculate the inner product with Psi*. That we are predicting a
probability for a measured outcome does not, at all, imply that human
consciousness plays any part in the measurement. In fact, as Hawking,
Penrose, and so many other physicists have so carefully calculated,
there is every reason to believe that quantum mechanics described the
cosmos billions of years before any humans and their conscious minds
existed.
In general, measurement is information exchange between two separate
physical objects. Neither object need be human, of course. The canonical
model for a measurement that transfers one bit of information is the
bi-level atom located along one arm of the Stern-Gerlach apparatus
described in 1978 (Physics Reports) by Scully, Shea, and McCullen. When
a spinning molecule collides with the bi-level atom, a single quantum of
energy is transferred to the atom. This is a real, physical, energetic
signal that carries information about the change in energy of the
molecule to the atom. Since energy is always conserved, the energy jump
in the detector atom always records the exact information about the
change in energy of the molecule.
One may, of course, still ask how human beings are able to observe
properties of our shared physical reality. I’m convinced that at the
most basic level of human percepta, more fundamental than learned, or
perhaps innate, shapes and objects, we all look at the same pattern of
minute color specks and see (and describe) the same specks. The key here
is to look only for each speck of color, as one might do to a
pointillist painting by Signac, say, ignoring any impression of physical
objects that the artist may have portrayed. If necessary, scientists
could employ such a basic technique to insure that the pattern which
carries information about results of a measurement (like the face of an
ammeter, for instance) really is observer independent. I’m convinced
that there are no cultually-inculcated tendencies at this most basic level.
Cordially,
Michael Devereux
_______________________________________________
fis mailing list
[email protected]
http://webmail.unizar.es/mailman/listinfo/fis
