Explicit embedding of gravity+Standard Model in E8 (new Lisi paper)

[dpackard]

atyy basically answered my question, sorry I was vague marcus. I was simply referring to the non-renormalization of straight-forwardly quantizing GR (unless it turns out to be asymptotically safe). I was trying to sort out whether Lisi's approach addressed this problem at all since the renormalizability of stringy gravitons is one of the much publicized advantages of string theory.

I noticed on http://www.science20.com/quantum_diaries_survivor/garrett_lisis_new_e8_paper#comments" a lengthy discussion in the comments between Nesti and Motl. Lubos obviously thinks GraviGUT is "foolish" - do his criticisms have any merit? Nesti seems to have held his own as far as the back and forth goes, but I cannot really evaluate the strengths of the arguments made. Something about mixing diffeomorphisms and Yang-Mills groups.

 

[MTd2]

No, they have no merit. You cannot trust him lately, he was even banned from posting on Jacques Distler's blog for not accepting being wrong, intellectually lazy and impolite.

 

[atyy]

I noticed on http://www.science20.com/quantum_diaries_survivor/garrett_lisis_new_e8_paper#comments" a lengthy discussion in the comments between Nesti and Motl. Lubos obviously thinks GraviGUT is "foolish" - do his criticisms have any merit? Nesti seems to have held his own as far as the back and forth goes, but I cannot really evaluate the strengths of the arguments made. Something about mixing diffeomorphisms and Yang-Mills groups.

There's another interesting discussion between Nesti and Distler and some others here:
http://golem.ph.utexas.edu/~distler/blog/archives/002140.html

 

[JollyJoker]

There's another interesting discussion between Nesti and Distler and some others here:
http://golem.ph.utexas.edu/~distler/blog/archives/002140.html

Lubos lays out his arguments http://motls.blogspot.com/2010/07/why-there-is-no-gravigut-symmetry.html" . If I understand correctly, they're basically the same as Distler's.

 

[MTd2]

No, they are not the same. Distler's calculations are clear and correct. The person you mention built a straw man. This post and thread on another physics problem are enlightening and keep that in your mind, since this is a subject that the person you mention worked on for years:

http://golem.ph.utexas.edu/~distler/blog/archives/002199.html#c032759

 

[MTd2]

I just found someone that claims triality of SO(8) as permutation property, just as I said above:

http://www.7stones.com/Homepage/octotut14.html

And he talks about finding using E8, or something embeded in that, since 1999

http://www.7stones.com/Homepage/AlgebraSite/algebra0.html

DAMN

 

[MTd2]

WORKSHOP SLIDES AND VIDEOS ARE OUT!:

http://www.birs.ca/birspages.php?task=eventvideos&event_id=10w5039

http://temple.birs.ca/~10w5039/

 

[arivero]

Given that the SciAm article will force some revisiting to this paper, let me to add my doubt against spin(11,1) or generically against SO(10) unification models: that it does not fit in maximum supergravity with kaluza klein; SO(10) is the symmetry group of the 9-sphere, and thus it invites to 9 extra dimensions.

Or we can stick with maximum sugra plus SO(10) and a bidimensional space time... after all, bidimensional space times are very in the music of string theory and also of other quantum gravity approaches.

In fact I believe to remember, but I am not sure, that the first appearing of E8 in modern theory was by doing dimensional reduction down to tridimensional or bidimensional space time. For GUT theories, the natural unification was only up to E6.