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Title: How is quantum evolution defined when no global clock exists?
Plain: Physical clocks in gravitating systems can stop or run backward, and in chaotic systems no variable may serve as a good clock everywhere. The usual recipe for evolution in time then breaks down.
Precise: For constrained systems in which every candidate clock function T has turning points along classical orbits (the global problem of time, for example chaotic Bianchi IX minisuperspace), determine whether a consistent unitary relational dynamics exists, by patching local clocks or otherwise, and whether its predictions are independent of the patching. An answer is a construction with proven clock-change consistency in a chaotic model, or a no-go theorem.
Settled by: A worked chaotic minisuperspace model with a proven consistent, patch-independent relational dynamics, or a proof that none exists.
Kind: phenomenon
Answer type: mechanism
References: (empty)
Literature status: open
Status note: (empty)
Posed since: (empty)