## (or, Cold Fusion Revisited?)

I do not have the physics or math background, but simplicity and elegance (expressed as symmetry) have always appealed to me. In an online paper titled, “*An Exceptionally Simple Theory of Everything,*” ( arXiv:0711.0770v1 [hep-th], Nov. 6, 2008, 31 pp, PDF), A. Garrett Lisi writes:

**"**The theory proposed in this paper represents a comprehensive unification program, describing all fields of the standard model and gravity as parts of a uniquely beautiful mathematical structure. The principal bundle connection and its curvature describe how the E8 manifold twists and turns over spacetime, reproducing all known fields and dynamics through pure geometry. Some aspects of this theory are not yet completely understood, and until they are it should be treated with appropriate skepticism. However, the current match to the standard model and gravity is very good. Future work will either strengthen the correlation to known physics and produce successful predictions for the LHC [Large Hadron Collider], or the theory will encounter a fatal contradiction with nature. The lack of extraneous structures and free parameters ensures testable predictions, so it will either succeed or fail spectacularly. If E8 theory is fully successful as a theory of everything, our universe is an exceptionally beautiful shape.

**"**

Lisi’s inspiration lies in an elegant and intricate mathetmatical shape called E_{8} — a complex structure with a rank of 8 (the maximum number of mutually commutative degrees of freedom) and 248 dimensions. It was first described in 1887, but was only fully explicated by mathematicians (with NPR audio) this year.

Lisi believes the algebra underlying this shape holds the key to the so-called Theory of Everything, the elusive equation to unite Einstein’s General Relativity with quantum mechanics. Relativity explains how the universe works on very large scales; quantum mechanics describes the world of tiny elementary particles.

BTW, there are some other beautiful shapes in this paper, lucid text and head-scratching equations! Here is also a reference to Lisi’s beautiful visualization that shows projections of various rotations of this E_{8} root system in eight dimensions: http://deferentialgeometry.org/anim/e8rotation.mov.

BTW BTW, if you really want to dig further into Lisi’s approach to the Theory of Everything, a good posting with background and context is available from Sabine Hossenfelder.