# How unitary cosmology generalizes thermodynamics and solves the inflationary entropy problem

@article{Tegmark2012HowUC, title={How unitary cosmology generalizes thermodynamics and solves the inflationary entropy problem}, author={Max Tegmark}, journal={Physical Review D}, year={2012}, volume={85}, pages={123517} }

We analyze cosmology assuming unitary quantum mechanics, using a tripartite partition into system, observer, and environment degrees of freedom. This generalizes the second law of thermodynamics to ``The system's entropy cannot decrease unless it interacts with the observer, and it cannot increase unless it interacts with the environment.'' The former follows from the quantum Bayes theorem we derive. We show that because of the long-range entanglement created by cosmological inflation, the…

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