Evolution without evolution and without ambiguities

@article{Marletto2017EvolutionWE,
  title={Evolution without evolution and without ambiguities},
  author={Chiara Marletto and Vlatko Vedral},
  journal={Physical Review D},
  year={2017},
  volume={95},
  pages={043510}
}
In quantum theory it is possible to explain time, and dynamics, in terms of entanglement. This is the timeless approach to time, which assumes that the universe is in a stationary state, where two noninteracting subsystems, the ``clock'' and the ``rest,'' are entangled. As a consequence, by choosing a suitable observable of the clock, the relative state of the rest of the universe evolves unitarily with respect to the variable labeling the clock observable's eigenstates, which is then… 
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