English

Don't Throw the Baby Out with the Bath Water

General Relativity and Quantum Cosmology 2023-06-19 v1 High Energy Physics - Theory

Abstract

I stress the importance of retaining a healthy classical limit while we search for an ultraviolet completion to quantum gravity. A key problem with negative-norm quantizations of higher derivative Lagrangians is that their classical limits do not correspond to real-valued metrics evolving in a real-valued spacetime. I also demonstrate that no completion based on the flat spacetime background S-matrix can suffice by providing an explicit example of a theory with unit S-matrix which still shows interesting changes in single-particle kinematics and in the evolution of its background. I discuss the implications of these considerations for the program of Asymptotic Safety. Finally, I urge that some attention be given to the possibility that quantum general relativity might make sense if only we could go beyond conventional perturbation theory.

Keywords

Cite

@article{arxiv.2306.09596,
  title  = {Don't Throw the Baby Out with the Bath Water},
  author = {R. P. Woodard},
  journal= {arXiv preprint arXiv:2306.09596},
  year   = {2023}
}

Comments

35 pages, 1 figure, uses LaTeX2e