Lisi argues that he is using a “mathematical trick” from what is called BRST theory, an established formalism used in string theory and quantum field theory, in which some bosons and fermions play the opposite of their usual roles (and are called “ghosts”). But in ordinary BRST theory, ghosts never manifest as detectable, physical particles, so it is unclear how they could do so consistently in the E8 theory.
Perhaps the longest public debate on the merits of Lisi’s theory took place primarily between Jacques Distler of the University of Texas at Austin and Lee Smolin of the Perimeter Institute for Theoretical Physics in Ontario, the latter of whom had been widely quoted in the media with unqualified praise for the theory. (Smolin says he was quoted out of context.) Smolin had also quickly written a paper suggesting ways to correct certain flaws in the E8 proposal. For the particles in the E8 theory to represent the known particles properly, the combination of smaller groups used to form the Standard Model must be embedded inside E8 in just the right way. Distler had demonstrated in his blog that this is a mathematical impossibility. So far as he was concerned, the theory was dead and not worth trying to resuscitate. Yet argument raged on over details of Distler’s proof and ultimately ended with neither side conceding. Lisi, incidentally, played very little part in these disputes.
Today the theory is being largely but not entirely ignored. Lisi, naturally, continues to work on it, as does Smolin. Lisi says that even if what Distler claims is true, it would only be true for the variant of E8 (“real E8”) originally used in his paper and that another variant (“complex E8”) would certainly work. Smolin argues that the press coverage gave the false impression that Lisi’s proposal was a finished work. “In reality,” he says, “almost every new theoretical proposal is first presented in a way that is flawed and incomplete, with open issues that need to be filled in.... While Lisi’s proposal has exciting aspects, this is the case with it as well.”
This article was originally published with the title Wipeout?.