Quantum gauge general relativity

[robousy]

I put this in the field theory section as its a gauge theory but it might just as well be in the GR section...

Has anyone heard of this.
http://citebase.eprints.org/cgi-bin/fulltext?format=application/pdf&identifier=oai:arXiv.org:gr-qc/0309041


Its apparently a renormalizable quantum gauge theory of gravity...

any comments?

 

[selfAdjoint]

I put this in the field theory section as its a gauge theory but it might just as well be in the GR section...

Has anyone heard of this.
http://citebase.eprints.org/cgi-bin/fulltext?format=application/pdf&identifier=oai:arXiv.org:gr-qc/0309041


Its apparently a renormalizable quantum gauge theory of gravity...

any comments?

I didn't read the paper but the abstract sounds fishy to me. Like some student who understood the details but missed the big point. If he just went ahead and path-integral quantized GR as a gauge theory, which is what he says, and what many others have tried, then how did he renormalize it? I'll look through the papr and see if he treats that question.

 

[selfAdjoint]

Here is a quote from the paper that will illuminate the discussion:

Quantum gauge general relativity is foumulated in the physics picture of grav-
ity. So, in quantum gauge general relativity, space-time is always flat and gravity
is treated as a kind of fundatmental interactions. In order to avoid confusing, we
do not introduce any comcept of curved space-time and we do not use any language
of geometry at present. It is suggest that anyone read this paper do not try to
find any geometrical meaning of any physical quantities, do not use the language of
geometry to understand anything of this paper and forget everything about the con-
cept of fibre bundles, connections, curved space-time metric, · ·

His theory isn't GR at all, it's a flat Minkowski space theory with a massive graviton. It may be renormalizable, and he may be able to reproduce Einstein's field equations, but that isn't reproducing GR, as has been shown in the case of string theory, which also produces a graviton in flat space. Two properties of GR that make it more than just another theory are the equivalence principle and general covariance. You lose these with flat space graviton theories.

I also checked the citations to this paper. Nobody cites it but he himself (sometime with coworkers). That suggests his approach isn't very interesting to the GR physics community.

 

[robousy]

lol, that certainly helps make things clearer.


I cannot understand why anyone would spend so much time and effort on something that is not going to work.

 

[selfAdjoint]

lol, that certainly helps make things clearer.


I cannot understand why anyone would spend so much time and effort on something that is not going to work.

Have you noticed string theory? A quarter of a century of publishing, literally thousands of workers, and no real predictions of observable physics yet. Getting published with a new theory that is not obviously wrong (in the sense of mathematical consistency and correct deployment of physics ideas) is a big thing. And there all by himself in China he can convince his ignorant superiors that it is ground breaking research and get funding. It isn't necessarily "wrong" as a theory, but it falls short of what he claims; renormalizable quantization of general relativity.

 

[eljose]

the question is is General Relativity a Gauge theory?..if so what is its gauge group?..and another important question is supposed that is showed that any Gauge theory is renormalizable ( i think t´Hoof proved it) but why then is GR non-renormalizable?..

 

[member 11137]

the question is is General Relativity a Gauge theory?..if so what is its gauge group?..and another important question is supposed that is showed that any Gauge theory is renormalizable ( i think t´Hoof proved it) but why then is GR non-renormalizable?..

Citation taken in "Quantum Gravity in 2 +1 Dimensions" Steven Carlip (I beg your pardon Sir because I did not ask the permission for) Cambridge monographs on mathematical physics 2003; section 2.4; page 21:
..."In gauge theories, constraints can tipically be understood as generators of infinitesimal gauge transformations. Gravity is not quite a gauge theory - ... -but it is useful to develop the analog of this result"...

 

[robousy]

If I understood your last post then you are saying that it is in fact a useful analogy even if it is not an accurate description of nature.

Why is this?

 

[member 11137]

If I understood your last post then you are saying that it is in fact a useful analogy even if it is not an accurate description of nature.
Why is this?

Why? You have the answer on the same page. ..."The analogy with gauge theories is so far very close, and the momentum constraints can indeed be interpreted as generators of spatial diffeomorphisms"... The discussions starts from the ADM approach.
I am not a specialist but I would say that we know procedees that work well in some parts of the theories and that we naturally try to extend them, to generalize them into some unknown domains; this is the case concerning quantum gravity, which is the construction of a theoretical bridge between the GR and the quantum approach.