A brief reply to Michael -- The postmodern position on science is not that
it is all a just a somehow useful construction, but that a particular class
in a particular society / culture has chosen to confront the world in a
particular style. The point is that, however useful this has turned out to
be (for the West), it does not exhaust possible other useful discourses and
perspectives that humans might have taken with respect to the world. It is
in this largest sense that science is 'observer contingent'. Perhaps one
of the best arguments for the validity of natural science is the example of
Einstein's realization of the physical equivalence of gravitation and
acceleration. This is pure sensual guts, using the biological system to
understand the world. But -- NOTE -- it was dependent upon a technology
that designed and built elevators! This again is observer dependence.
STAN
>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
>
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Received on Sun Jun 25 21:44:02 2006
