8. ON QUANTUM THEORY WITHOUT OBSERVERS
One of the fundamental questions of physics is whether pure
states (i.e., states undisturbed by avoidable noise) are states
such that the outcome of every measurement can be exactly
predicted. Classical physics is based on the proposition that the
answer to the question is yes. Orthodox quantum mechanics is a
theory based on the proposition that the answer is no, and that
we can only make precise quantitative statements about probab-
ilities, the limitation due to an essential interaction between
the observer and that which is being measured.
.. ... S. Goldstein (Rutgers University New Brunswick, US), in
the first of a two-part review, discusses the idea of quantum
theory without observers, and suggests that despite the claims of
most of the originators of quantum theory, the appeal at a fund-
amental level to observers and measurement, which is so prominent
in orthodox quantum theory, is not needed to account for quantum
phenomena. Referring to the classical Bohr-Einstein debate,
Goldstein says the debate has already been resolved in favor of
Einstein. What Einstein desired and Bohr held impossible -- an
observer-free formulation of quantum mechanics in which the
process of measurement can be analyzed in terms of more fund-
amental concepts, does in fact exist, and there are many such
formulations, several of which have the potential to become a
serious program for the construction of a quantum theory without
observers. QY: Sheldon Goldstein, Rutgers University New
Brunswick 908-932-8789 (Physics Today March 1998)