An Exceptionally Simple Theory of Everything
The paper's goal is to describe how the combined structure and dynamics of all gravitational and Standard Model particle fields are part of the E8 Lie algebra.
[4] Scientific American reported in March 2008 that the theory was being "largely but not entirely ignored" by the mainstream physics community, with a few physicists picking up the work to develop it further.
[5] In July 2009, Jacques Distler and Skip Garibaldi published a critical paper in Communications in Mathematical Physics called "There is no 'Theory of Everything' inside E8",[6] arguing that Lisi's theory, and a large class of related models, cannot work.
Lisi states the theory is young and incomplete, requiring a better understanding of the three fermion generations and their masses, and places a low confidence in its predictions.
Lisi made a further presentation for the International Loop Quantum Gravity Seminar on November 13, 2007,[13] and responded to press inquiries on an FQXi forum.
In this paper, Distler and Garibaldi offer a proof that it is impossible to embed all three generations of fermions in E8, or to obtain even the one-generation Standard Model.
[25] Addressing the one generation case, in June 2010 Lisi posted a new paper on E8 Theory, "An Explicit Embedding of Gravity and the Standard Model in E8",[26] eventually published in a conference proceedings, describing how the algebra of gravity and the Standard Model with one generation of fermions embeds in the E8 Lie algebra explicitly using matrix representations.
[27] Roberto Percacci's "Mixing internal and spacetime transformations: some examples and counterexamples"[28] addresses a general loophole in the Coleman–Mandula theorem also thought to work in E8 Theory.
[29] In a joint paper with Lee Smolin and Simone Speziale,[30] published in Journal of Physics A, Lisi proposed a new action and symmetry-breaking mechanism.
In December 2011, in a paper for a special issue of the journal Foundations of Physics, Michael Duff argued against Lisi's theory and the attention it has received in the popular press.
