# A New Perspective on Time Reversal Motivated by Quantum Gravity

### APA

Ashtekar, A. (2021). A New Perspective on Time Reversal Motivated by Quantum Gravity. Perimeter Institute. https://pirsa.org/21060094

### MLA

Ashtekar, Abhay. A New Perspective on Time Reversal Motivated by Quantum Gravity. Perimeter Institute, Jun. 15, 2021, https://pirsa.org/21060094

### BibTex

@misc{ pirsa_PIRSA:21060094, doi = {10.48660/21060094}, url = {https://pirsa.org/21060094}, author = {Ashtekar, Abhay}, keywords = {Quantum Foundations}, language = {en}, title = {A New Perspective on Time Reversal Motivated by Quantum Gravity}, publisher = {Perimeter Institute}, year = {2021}, month = {jun}, note = {PIRSA:21060094 see, \url{https://pirsa.org}} }

Pennsylvania State University

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Abstract

Time Reversal T is usually discussed in the traditional framework of quantum mechanics in which T is represented by an anti-unitary operator. But quantum gravity may well need generalization of standard quantum mechanics which may not preserve even its linear structure, let alone the unitarity of dynamics and anti-unitarity of T. Then the currently used arguments to conclude that T violation is a fundamental aspect of Nature will break down. Fortunately, it turns out that one can analyze the T-violation experiments in a much more general setting, of which classical and quantum mechanics are special cases. The setting does not require a Hilbert space, or linearity of either dynamics or symmetry operations such as T. Nonetheless, somewhat surprisingly, one would still be to use the current experiments to conclude that there is T violation at a fundamental level under rather minimal assumptions on the structure of the final quantum gravity theory.