Garett Lisi recently posted An Exceptionally Simple Theory of Everything on ArXiv. Don’t expect the article to really be “exceptionally simple”, the title is really a pun on the fact that E8 is the largest exceptional simple Lie group. There’s nothing really simple about all this, except that it’s a beautiful form of symmetry.
This work was quickly picked up all over the place, for example at Backreaction, where a good discussion followed. It even made it to Slashdot, where whatever discussion was typical Slashdot (“it’s funny, laugh!”. Not useful, but entertaining.
Unfortunately, it also made it to less reputable science outlets. My favorite blogger made predictable comments about it being stupidly wrong, rejoicing in an arXiv demotion from hep-th (“professional”) to gen-ph (“laymen’s fantasies”):
Update I: the preprint was re-classified from the professional hep-th archive to gen-ph, general physics, an archive mostly dedicated to laymen’s fantasies. Thanks God. Comment for general readers: this preprint is of course not peer-reviewed and probably won’t get published anywhere.
That demotion may very well be Motl’s own fantasy, as the preprint still appears as hep-th for me. In any case, you can compare Lubos’ “professional” piece of work to, say, John Baez’s reaction to the exact same event. True, Baez also shows some skepticisim, which I will share for the moment, but he remains healthily neutral, whereas Motl “exploded in laughter” at the first equation in the paper. More importantly, Baez, unlike Motl, starts looking at similar work, like earlier attempts at unifying forces using SU(5). That’s the right way to go. Even if the paper is totally bogus (which I don’t think it is, more likely to be subtly bogus), you still have to prove it, which Lubos Motl spectacularly failed to do as usual.
So… Why be skeptical? Simply because that’s not the first time folks look at E8, and even if Garrett Lisi’s approach is innovative, it may still very well be entirely wrong, until experiments show the predicted additional particles. But at least, Garrett is ready to take that risk, and that’s worth a lot in my book. And, if nothing else, he provided us with a very beautiful video:
So at this time, what I find a source of concern is not Garrett’s article itself, it’s all the publicity around it. Early publicity for something as “grandiose” as a “theory of everything” can prove fatal to the researcher if he turns out to be wrong, or to not make as much progress as expected. That’s in no small part what happened to Laurent Nottale. And just like for Nottale, that would be a shame if Garrett Lisi ended up doing nothing more than surfing in Hawaii…
And I also believe that Garrett Lisi’s work is absolutely not in conflict with my own ideas, nor any step in that direction. In other words, the paper I submitted still shows, in my opinion, just how far Garrett’s work is from a “theory of everything”.