Free will, undecidability, and the problem of time in quantum gravity

Understand

In quantum gravity there is no notion of absolute time.

• Like all other quantities in the theory, the notion of time has to be introduced "relationally", by studying the behavior of some physical quantities in terms of others chosen as a "clock".
• We have recently introduced a consistent way of defining time relationally in general relativity.
• When quantum mechanics is formulated in terms of this new notion of time the resolution of the measurement problem can be implemented via decoherence without the usual pitfalls.