This paper by 't Hooft looks interesting, I would like to hear some thoughts and comments !.(adsbygoogle = window.adsbygoogle || []).push({});

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.

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# 't Hooft new paper

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