Gerard 't Hooft's Probing Canonical Quantum Gravity

[John86]

This paper by 't Hooft looks interesting, I would like to hear some thoughts and comments !.

http://arxiv.org/abs/1009.0669
Probing the small distance structure of canonical quantum gravity using the conformal group
Authors: Gerard 't Hooft
(Submitted on 3 Sep 2010)
Abstract: In canonical quantum gravity, the formal functional integral includes an integration over the local conformal factor, and we propose to perform the functional integral over this factor before doing any of the other functional integrals. By construction, the resulting effective theory would be expected to be conformally invariant and therefore finite. However, also the conformal integral itself diverges, and therefore the actual situation is more delicate. The effects of a renormalization counter term are considered, including the associated problem of unitarity violation, such as a Landau-like ghost. Adding (massive or massless) matter fields does not change the picture; to confirm this, detailed calculations were necessary, and they are presented. Some alternative ideas are offered, including a more daring speculation, which is that no counter term should be allowed for at all. This has far-reaching and important consequences, which we discuss. A surprising picture emerges of quantized elementary particles interacting with a gravitational field that is "partly classical". This approach was inspired by a search towards the reconciliation of Hawking radiation with unitarity and locality, and it offers basic new insights there.

I liked his statements about the emergence of quantum mechanics at page 12.

 

[Naty1]

I like that his conclusions actually point out his own uncertainties and ambiguities of the mathematics. Sounds more like an intial foray with loose ends rather than a firm and final analysis.

 

[Naty1]

By coincidence I just came across this from wikipedia:

Asymptotic freedom is a feature of quantum chromodynamics (QCD), the quantum field theory of the interactions of quarks and gluons which was discovered in 1973 by David Gross and Frank Wilczek, and by David Politzer. Although these authors were the first to understand the physical relevance to the strong interactions, in 1969 Iosif Khriplovich discovered asymptotic freedom in the SU(2) gauge theory as a mathematical curiosity, and Gerardus 't Hooft in 1972 also noted the effect but did not publish. For their discovery, Gross, Wilczek and Politzer were awarded the Nobel Prize in Physics in 2004.

So maybe t'Hooft has decided "better to publish" some incomplete but new insightsthan to be overlooked?