a non-string QG resource

[Martin]

best audio I've heard in some time covering current status of QG research (in first 10 minutes) plus Barrett's work on 3D

 

http://www.newton.cam.ac.uk/webseminars/pg+ws/2006/ncg/ncgw02/'>http://www.newton.cam.ac.uk/webseminars/pg+ws/2006/ncg/ncgw02/

 

 

also great talk by Alain Connes on how he realized the standard model of particle physics and gravity in a non-string approach to unification he calls NCG---but Urs Schreiber calls "spectral geometry"

 

both these talks are in MP3

 

I think both are worth listening to----they are hour talks

given at the 4-8 September workshop at Newton Institute Cambridge

http://www.newton.cam.ac.uk/

 

John Barrett is at Nottingham. He's pretty remarkable.

Alain Connes makes the headlines--he's getting a lot of attention these days because of capturing the standard model+graviton-----unlike superstringM, Connes theory risks making falsifiable predictions about mass relationships, as he explains in the talk.

 

But all Connes gets is particle physics plus a graviton-------this is not a quantization of GR: it is not a quantization of spacetime geometry.

AND BARRETT JUST GOT CONNES RESULT ON THE SIDE

 

Barrett's paper came out same time as Connes, but Barrett didnt even take time to mention the result in his talk. Barrett is working on a full theory of quantum gravity (spin networks, Feynman diagrams) including matter.

 

In Barrett's talk, you can hear Connes interrupting a lot.

 

If I was a young grad student and lucky enough to have my choice of any school, I might very well choose Uni Nottingham. I am impressed by Barrett.

 

I know someone who just made that choice----did their Masters in non-string QG at Marseille with Rovelli and then moved to Nottingham for the PhD (starting this Fall). After listening, it is now clearer to me why they did.

 

here is Barrett's recent preprint where he gets the same result as Connes just posted:

http://arxiv.org/abs/hep-th/0608221

A Lorentzian version of the non-commutative geometry of the standard model of particle physics

John W. Barrett

14 pages

"A formulation of the non-commutative geometry for the standard model of particle physics with a Lorentzian signature metric is presented. The elimination of the fermion doubling in the Lorentzian case is achieved by a modification of Connes' internal space geometry so that it has signature 6 (mod 8) rather than 0. The fermionic part of the Connes-Chamseddine spectral action can be formulated, and it is shown that it allows an extension with right-handed neutrinos and the correct mass terms for the see-saw mechanism of neutrino mass generation."

 

here is Connes preprint (Connes may be world's greatest live working mathematician at the present but I think Barrett is more grounded in physics and it shows IMHO)

 

http://arxiv.org/abs/hep-th/0608226

Noncommutative Geometry and the standard model with neutrino mixing

Alain Connes

17 pages

We show that allowing the metric dimension of a space to be independent of its KO-dimension and turning the finite noncommutative geometry F-- whose product with classical 4-dimensional space-time gives the standard model coupled with gravity--into a space of KO-dimension 6 by changing the grading on the antiparticle sector into its opposite, allows to solve three problems of the previous noncommutative geometry interpretation of the standard model of particle physics:

The finite geometry F is no longer put in "by hand" but a conceptual understanding of its structure and a classification of its metrics is given.

The fermion doubling problem in the fermionic part of the action is resolved.

The spectral action of our joint work with Chamseddine now automatically generates the full standard model coupled with gravity with neutrino mixing and see-saw mechanism for neutrino masses. The predictions of the Weinberg angle and the Higgs scattering parameter at unification scale are the same as in our joint work but we also find a mass relation (to be imposed at unification scale)."

 

It is still amazing to me that with MP3 audio and the web we can actually hear these two leading edge guys talking at an historical conference at Cambridge in the midst of real breakthroughs in QG.

[Martin]

best audio I've heard in some time covering current status of QG research (in first 10 minutes) plus Barrett's work on 3D

 

http://www.newton.cam.ac.uk/webseminars/pg+ws/2006/ncg/ncgw02/

 

 

also great talk by Alain Connes on how he realized the standard model of particle physics and gravity in a non-string approach to unification he calls NCG---but Urs Schreiber calls "spectral geometry"

 

both these talks are in MP3

 

...real breakthroughs in QG.

 

to get the talks, if it isn't obvious, you go to that link

and click on 6 September talk by Barrett

http://www.newton.cam.ac.uk/webseminars/pg+ws/2006/ncg/ncgw02/0906/barrett/

 

and over on left you click on MP3 and almost immediately the hour lecture starts---which you can save by dragging if you want.

 

there is also the 4 September talk by Connes on same menu

http://www.newton.cam.ac.uk/webseminars/pg+ws/2006/ncg/ncgw02/0904/connes/

 

Urs Schreiber has 4 BLOGS commenting and explaining Connes recent paper. He is the one that calls it "spectral" geometry, instead of non-commutative geometry. Urs comments are helpful. I will put links

http://golem.ph.utexas.edu/category/2006/09/connes_on_spectral_geometry_of.html

 

http://golem.ph.utexas.edu/category/2006/09/connes_on_spectral_geometry_of_1.html

 

http://golem.ph.utexas.edu/category/2006/09/connes_on_spectral_geometry_of_2.html#more

 

http://golem.ph.utexas.edu/category/2006/09/connes_on_spectral_geometry_of_3.html#more

[ajb]

Nottingham has a relatively new particle theory group within the department of physics. It is headed by Ed Copeland (formally of Sussex). The group has an interest in string cosmology. So indeed Nottingham would be an interesting place to be as you have both string theorists and loop gravity people.

 

 

Barrett is with the quantum gravity group which is based in the mathematics department.

 

I have several friends at Nottingham in the particle group , both students and members of staff. I plan to visit at some point soon. More a social visit I think!

 

Here is a link

 

 

http://www.nottingham.ac.uk/physics/research/particles/index.html

[Martin]

the Monday after the official conference, Barrett gave a talk on HIS paper that came out at the same time as Connes with the same key result.

There is no video, because it is after the official 4-8 September thing was over. A kind participant put hastily scribbled notes online---but doubted that most people would find them legible.

 

the link given was this

 

there are a total of 9 slides in sequence

you can advance the slide by clicking on the RHS of a twopage "photostream" box to the right of the slide

 

in/photostream/

 

 

===================

would be good to have a link to the maths department at Uni Nottingham, since that is where Barrett is.

http://www.maths.nott.ac.uk/index.html

 

barrett:

http://www.maths.nottingham.ac.uk/htbin-local/staff.info?jwb

 

what looks like an old homepage

http://www.maths.nottingham.ac.uk/personal/jwb/

with a circa 1998 history of QG (discovery and development of Barrett-Crane spinfoam model)

http://www.maths.nottingham.ac.uk/personal/jwb/qg.4d.html

 

news:

http://www.maths.nott.ac.uk/news/index.html

 

seminars

http://www.maths.nottingham.ac.uk/seminars/index.html

 

seminar schedule for Spring 2006 (Fall 2006 seems unavailable)

http://www.maths.nottingham.ac.uk/QG/seminars.html

 

Yeah, ajb YOU may not be so interested in Barrett's group because it is over in Maths and you are in Physics. and superficially Barrett's group on the web looks minor----apparently not too much going on, just a few visitors, schedule of seminars out of date. but I know the names on the spring seminar list and it looks good to me. (Besides Barrett, there is Krasnov and Aristide Baratin was visiting in the spring and gave a seminar).

 

I will keep a lookout for what happens there this Fall. Let you know if I notice anything special.

[ajb]

Yeah' date=' ajb YOU may not be so interested in Barrett's group because it is over in Maths and you are in Physics.[/quote']

 

I am in fact in a mathematics department.

 

Some of the quantum gravity group areas of interest overlap with mine, topological field theory and quantisation of gauge systems.

 

I thought I would mention something about Ed Copeland's group as some of their interests parallel that of Barrett's group.