2001/10/31 by Carlo Rovelli · 10 citations
Physics and Astronomy · #Classical mechanics #Noncommutative and Quantum Gravity Theories #Observable #Operator (biology) #Physics #Quantum #Quantum Mechanics and Applications #Quantum gravity #Quantum mechanics #Relativity and Gravitational Theory #Theoretical physics #gr-qc
paper · pdf · doi:10.1103/physrevd.65.124013
published as Phys.Rev.D65:124013,2002 · 9 pages, no figures references added
arxiv created 2002/01/21 · openalex publication_date 2002/06/04 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
I discuss the distinction between the notion of a partial observable and the notion of a complete observable. Mixing up the two is frequently a source of confusion. The distinction bears on several issues related to observability, such as (i) whether time is an observable in quantum mechanics, (ii) what are the observables in general relativity, and (iii) whether physical observables should or should not commute with the Wheeler-DeWitt operator in quantum gravity. I argue that the extended configuration space has a direct physical interpretation, as the space of the partial observables. This space plays a central role in the structure of classical and quantum mechanics and the clarification of its physical meaning sheds light on this structure, particularly in the context of general covariant physics.