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On the problem of time in two and four dimensions

T. A. Larsson
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Abstract

In general-covariant theories the Hamiltonian is a constraint, and hence there is no time evolution; this is the problem of time. In the subcritical free string, the Hamiltonian ceases to be a constraint after quantization due to conformal anomalies, and time evolution becomes non-trivial and unitary. It is argued that the problem of time in four dimensions can be resolved by a similar mechanism. This forces us to challenge some widespread beliefs, such as the idea that every gauge symmetry is a redundancy of the description.

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T. A. Larsson. 2005-09-05. On the problem of time in two and four dimensions. https://arxiv.org/abs/hep-th/0509039

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