PIRSA:12070015

# Making the Case for Conformal Gravity

### APA

Mannheim, P. (2012). Making the Case for Conformal Gravity. Perimeter Institute. https://pirsa.org/12070015

### MLA

Mannheim, Philip. Making the Case for Conformal Gravity. Perimeter Institute, Jul. 26, 2012, https://pirsa.org/12070015

### BibTex

@misc{ pirsa_12070015, doi = {10.48660/12070015}, url = {https://pirsa.org/12070015}, author = {Mannheim, Philip}, keywords = {}, language = {en}, title = {Making the Case for Conformal Gravity}, publisher = {Perimeter Institute}, year = {2012}, month = {jul}, note = {PIRSA:12070015 see, \url{https://pirsa.org}} }

Philip Mannheim University of Connecticut

**Collection**

**Talk Type**Scientific Series

## Abstract

We discuss the shortcomings of Einstein gravity at both the classical and quantum levels. We discuss the motivation for replacing Einstein gravity by conformal gravity. We show how the conformal gravity theory is able to naturally solve the quantum gravity problem, the vacuum zero-point energy problem, the vacuum zero-point pressure problem, the cosmological constant problem, and the dark matter problem. Central to its viability as aquantum theory is that the conformal theory is both renormalizable and unitary, with unitarity being obtained because the theory is a PTsymmetric rather than a Hermitian theory. We show that in the conformal theory there can be no a priori classical curvature, with all curvature having to result from quantization. In the conformal theory gravity requires no independent quantization of its own, with it being quantized solely by virtue of its being coupled to a quantized matter source. In the absence of quantum mechanics then there would thus be no gravity, with it being the desire to start with a classical gravity theory and then quantize itthat has prevented the construction of a sensible quantum gravity theory. We show that the macroscopic classical theory that results from the quantum conformal theory incorporates global physics effects coming from the material outside of galaxies (viz. the rest of theuniverse), global physics effects that are found to provide for a detailed accounting of a comprehensive set of 138

galactic rotation curves with no adjustable parameters other than galactic mass to light ratios, and with the need for no dark matter whatsoever. With these global effects eliminating the need for dark matter, we see that invoking dark matter in galaxies could potentially be nothing more than an attempt to describe global physics effects in purely local galactic terms.