PageWootters
PageWootters, also known as the Page-Wootters mechanism, is a framework in quantum theory for describing time as an emergent property of correlations within a composite quantum system. Proposed by Don N. Page and William K. Wootters in 1983, it addresses the problem of time by treating time as relational rather than external.
In the setup, the universe is partitioned into a clock subsystem C and a system of interest
The conditional state of S given a clock reading t is defined as |ψ_S(t)⟩ ∝ ⟨t|Ψ⟩, where |t⟩
Interpretation and implications: the mechanism treats time as relational and shows how conventional quantum dynamics can
Limitations and critiques: dependence on an accurate, isolated clock; questions about the exact conditions under which
Applications and influence: used in conceptual studies of quantum cosmology, gravity, and quantum information to illustrate