E8 as predictor of subatomic particles?

This was/is one of the possible symmetries in the superstring (now I guess it is the M-Theory regime). One of the E8's would denote the universe that we see, the other a "shadow" universe that would share space with, but not interact with ours (except possibly couple with our gravity, but that has never been conceded, it was only viewed as a possibility).

Two points: even if the other E8 "mater could interact through coupling with our gravity this model does not describe the currently postulated ?'Dark Matter'.

Second, neither any of the string theories or M theory can make testable predictions; they are theories in name only. They have been around in one form or another since the 1920's, first in an attempt to describe electricity in terms of geometry in the same way that Einstein\Minkowski described gravity in the form of a geometry; this (Kaluza/Kline theory) failed miserably.

It has been reincarnated since then several times, once in the early 1970's to describe strong force interactions in which it again failed miserably. These were successfully described by quantum chromodynamics. Finally in the late 70's/early 80's as a model for a TEO (theory of everything) combining gravity with the particle forces. So far no luck here either.

I am not aware of any E8 x E8 symmetry in standard quantum field theory.

TCR,

Thank you for the detailed reply. I particularly appreciate your historical perspective.

It seems that E8 may be a case in which something symmetrical and powerfully complex MUST surely have a greater utility. Even if E8 turns out to have no larger usefulness, the map of its root system will still possess wondrous beauty.

I have read in many places (for one, an article in "Brain and Cognition" by Dahlia Zaidel of UCLA) that all of us have a powerful innate attraction to physical symmetry in faces when we are mate-selecting. Perhaps, E8 has a particularly elegant countenance to suitors on an intellectual plane.

Symmetry certainly plays an important role in physics. Many of the conservation laws are believed to come about because of "broken symmetries" of quantum fields. All useful particle models exhibit what is know as the Yang-Mills symmetry. As a matter of fact symmetric properties are powerful mathematic tools used to guide the development of particle physics.

String theory will be testable once the 2 satellites reach the other side of the sun and send test signals to the 2 on the side we see - but it will take years until they're all in place.

However there's a new theory of everything using E8:
http://arxiv.org/abs/0711.0770

and that's a general outline for the non-techies:
http://backreaction.blogspot.com/2007/11/theoretically-simple-exception-of.html