Time, Change, Observables, and Quantum Gravity
A special issue of Entropy (ISSN 1099-4300). This special issue belongs to the section "Time".
Deadline for manuscript submissions: 30 May 2025 | Viewed by 105
Special Issue Editor
Special Issue Information
Dear Colleagues,
While change is evident in daily life and classical physics, change has seemed to be missing in canonical quantum gravity, from which change in daily life and classical physics presumably ought to emerge somehow. Part of the issue is the gauge (coordinate or diffeomorphism) freedom of General Relativity, which is external, distinguishing it from that of electromagnetism and even Yang–Mills theories. Recent decades have seen a variety of arguments, calculations, definitions, etc., aiming to resolve the puzzle of missing change in canonical quantum gravity. Perhaps canonical gravity needs a distinctive treatment of the Hamiltonian constraint, or a manifestly Lagrangian equivalent classical basis and associated redefinition of observables, or a new way to impose constraints, or a distinctive treatment for the Hamiltonian constraint. Is change missing already in classical canonical gravity, or is the classical problem largely verbal and the real problem quantum mechanical? If the quantum problem is more clearly genuine, does it have a principled solution? Why do ways of treating constraints that seem arguable classically appear perhaps inevitable quantum mechanically? To what degree can stipulative definitions and postulations be avoided in favour of calculations and reflective equilibrium? Papers addressing issues on this topic are invited for this Special Issue.
Dr. J. Brian Pitts
Guest Editor
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Keywords
- change
- observables
- constrained Hamiltonian dynamics
- gauge freedom
- quantum gravity
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