# Computers with Closed Timelike Curves Can Solve Hard Problems Efficiently

@article{Brun2002ComputersWC, title={Computers with Closed Timelike Curves Can Solve Hard Problems Efficiently}, author={Todd A. Brun}, journal={Foundations of Physics Letters}, year={2002}, volume={16}, pages={245-253} }

A computer which has access to a closed timelike curve, and can thereby send the results of calculations into its own past, can exploit this to solve difficult computational problems efficiently. I give a specific demonstration of this for the problem of factoring large numbers and argue that a similar approach can solve NP-complete and PSPACE-complete problems. I discuss the potential impact of quantum effects on this result.

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