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arXiv · 2108.02771

The quantum theory of time: a calculus for q-numbers

Samuel Kuypers
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Abstract

In quantum theory, physical systems are usually assumed to evolve relative to a c-number time. This c-number time is unphysical and has turned out to be unnecessary for explaining dynamics: in the timeless approach to quantum theory developed by Page & Wootters (1983), subsystems of a stationary universe can instead evolve relative to a 'clock', which is a quantum system with a q-number time observable. Page & Wootters formulated their construction in the Schr\"odinger picture and left open the possibility that the c-number time still plays an explanatory role in the Heisenberg picture. I formulate their construction in the Heisenberg picture and demonstrate that c-number time is completely unnecessary in that picture, too. When the Page-Wootters construction is formulated in the Heisenberg picture, the descriptors of physical systems are functions of the clock's q-number time, and derivatives with respect to this q-number time can be defined in terms of the clock's algebra of observables, resulting in a calculus for q-numbers.

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Samuel Kuypers. 2021-08-05. The quantum theory of time: a calculus for q-numbers. https://doi.org/10.1098/rspa.2021.0970

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