Realism, positivism, instrumentalism, and quantum geometry

Abstract

75he roles of classical realism, logical positivism, and pragmatic" instrumentatism in the shaping of fundamental ideas in quantum physics are examined in the light of some recent historical and sociological studies of the factors that influenced their development. It is shown that those studies indicate that the conventionalistic form of instrumentalism that has dominated all the major post-World War H developments in quantum physics is not an outgrowth of the Copenhagen school, and that despite the "schism" in twentieth century physics created by the Bohr-Einstein "disagreements" on foundational issues in quantum theory, both their philosophical stands were very much opposed to those of conventionalistic instrumentalism. Quotations .from the writings of Dirac, Heisenberg, Popper, Russell, and other influential thinkers, are provided, illustrating the fact that, despite the various divergencies in their opinions, they all either opposed the instrumentalist concept of "truth'" in general, or its conventionalistic version in post-World War H quantum physics in particular. The basic epistemic ideas of a quantum geometry approach to quantum physies ate reviewed and discussed from the point of view of a quantum realism that seeks to reconcile Bohr's "positivism" with Einstein's "reatism" by emphasizing the existence of an underlying quantum reality, in which the), both believed. This quantum geometry framework seeks to introduce geometro-stochastic concepts that are specifically designed for the systematic description of that underlying quantum reality, by devetop#~g the conceptual and mathematical tools that are most appropriate for such a use.

Foundational problems in quantum gravity and quantum cosmology

“…As discussed in Ref. 5, and extensively documented in Chapter 12 of I, such an approach is totally at odds with that employed by the founders of relativity theory as well as of quantum mechanics. For example, W. Heisenberg remarked on one occasion that "if predictive power were indeed the only criterion for truth, Ptolemy's astronomy would be no worse than Newton's (Ref.…”

“…whereas the remaining six dynamical Einstein equations are shown to be equivalent to the equations (5) which are expressed in terms of Poisson brackets, obtained by replacing partial derivatives with functional derivatives in their customary definition in Hamiltonian classical mechanics. After developing the foundations for the above outlined approach to classical canonical gravity, Dirac presented one of the most compelling reasons for quantizing CGR gravity: "There is no experimental evidence for the quantization of the gravitational field, but we believe quantization should apply to all fields of physics.…”

“…12.1 of I, as well as in Ref. 5), in his later years Einstein became a "physical realist," who repudiated some of the philosophical implications of the statement that spacetime has no "physical objectivity." Nevertheless, even in his autobiographical notes, (~3) first published in 1949, Einstein never retracted the contention that spacetime coincidences are, in effect, the only ultimate manifestation of the physical reality which underlies the principle of equivalence and which constitutes the basis of the principle of general covariance in its modem form, discussed in the preceding section.…”

“…Thus, in sharp contrast with the conventionalistically based instrumentalist attitude that came to prevail in theoretical physics soon after World War II (for historical reasons analyzed in Ref. 5, and extensively documented in Chap. 12 of I), Einstein's underlying epistemological attitude was that "the question whether the structure of [the spacetime] continuum is Euclidean, or in accordance with Riemann's general scheme, or otherwise, is ... a physical question which must be answered by experience, and not a question of mere convention to be selected on practical grounds" (Ref.…”