Contemporary physics employs multiple, mutually incompatible conceptions of time. Although these temporal frameworks are typically analyzed within their own theoretical domains, they are rarely examined together within a unified structural analysis. This paper develops a taxonomy of eight distinct temporal models—those of Newtonian mechanics, special relativity, general relativity, cosmology, statistical mechanics, quantum mechanics, quantum field theory, and quantum gravity—and compares them along four independent dimensions: ontological status, operational measurement, causal and dynamical role, and foliation or global-structure requirements. The comparison shows that the temporal concepts used across physics are not merely diverse but structurally incommensurable. In particular, it reframes the traditional problem of time as one instance of a broader structural conflict among the temporal frameworks employed across contemporary physics. The resulting fragmentation explains long-standing tensions, including those between quantum mechanics and general relativity, between quantum field theory on curved spacetime and general relativity, and between microscopic reversibility and macroscopic irreversibility. The taxonomy provides a conceptual map for understanding these incompatibilities and clarifies the structural constraints that any future unification, quantum-gravity program, or emergent-time proposal must satisfy. This paper forms part of a broader investigation into the measurement and representation of time in physical theory.
Julian Severin (Sat,) studied this question.