Making the Case for Conformal Gravity

By P. Mannheim. Foundations of physics, 2011

344 citations recorded by the source corpus.

We review some recent developments in the conformal gravity theory that has been advanced as a candidate alternative to standard Einstein gravity. As a quantum theory the conformal theory is both renormalizable and unitary, with unitarity being obtained because the theory is a PT symmetric rather than a Hermitian theory. We show that in the 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. Moreover, because it is this very coupling that fixes the strength of the gravitational field commutators, the gravity sector zero-point energy density and pressure fluctuations are then able to identically cancel the zero-point fluctuations associated with the matter sector. In addition, we show that when the conformal symmetry is spontaneously broken, the zero-point structure automatically readjusts so as to identically cancel the cosmological constant term that dynamical mass generation induces. We show that the macroscopic classical theory that results from the quantum conformal theory incorporates global physics effects that provide for a detailed accounting of a comprehensive set of 138 galactic rotation curves with no adjustable parameters other than the 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. Finally, we review some recent work by ’t Hooft in which a connection between conformal gravity and Einstein gravity has been found.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2d395edd566a581a6fb7cbfd343613aa8f98800a

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Citations in the corpus

Modified Gravity and Cosmology (2011, background): “Such a proposal has been advocated by Mannheim [866] in the case of conformal Gravity.”
Dynamically induced Planck scale and inflation (2015, background): “The gravitational kinetic terms suppressed by the dimensionless constants f0 and f2 contain four derivatives: thereby the graviton contains a massive spin-2 ghost component [87], which is possibly problematic for energies above its mass M2 = |f2|M̄Pl/ √ 2: we do not address the issue of finding a se”