Foundational problems in quantum gravity and quantum cosmology

Abstract

The conventionalistically based instrumentalist epistemology and methodology underlying the various approaches to the quantization of gravity is contrasted with the operationally based logical analysis practiced by the founders of relativity theory and quantum mechanics in developing their respective disciplines. The foundational problems to which they give rise are described. Their origins are traced to instrumentalist practices which have been in the past the objects of criticisms by Dirac, Heisenberg, Born, and others, but whieh have nevertheless prevailed in relativistic quantum physics after the emergenee of the conventional renormalization program. The operationally based premises of a recently developed geometro-stochastic approach to the quantization of gravity are analyzed. It is shown that their roots lie in the epistemology adopted by the founders of relativity theory and quantum mechanics, and that they reflect a conceptualization of quantum reality which offers the possibility of a resolution of the main foundational problems encountered by the other approaches to quantum gravity.

Time and observables in unimodular gravity

“…In Rovelli's approach, all the frames and all the test particles are assumed to be material objects. However, to implement the process and simplify the calculation, one has to neglect the energy-momentum tensor of matter fields in the Einstein equations, as well as their contributions to the dynamical equations for matter fields [19]. Of course the price that one has to pay for this neglect is obtaining an indeterministic interpretation of the Einstein equations.…”