# Semiclassical limit problems with concurrent use of several clocks in quantum cosmology

@article{Alexandre2021SemiclassicalLP, title={Semiclassical limit problems with concurrent use of several clocks in quantum cosmology}, author={Bruno Alexandre and Jo{\~a}o Magueijo}, journal={Physical Review D}, year={2021} }

We revisit a recent proposal for a definition of time in quantum cosmology, to investigate the effects of having more than one possible type of clock “at the same time”. We use as test tube an extension of Einstein gravity with a massless scalar field in which the gravitational coupling GN is only a constant on-shell, mimicking the procedure for Λ in unimodular gravity. Hence we have two “simultaneous” clocks in the theory: a scalar field clock, and the conjugate of GN . We find that attempts…

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