News on Garrett Lisi’s E8 theory
Lisi posted this yesterday over at Physics Forums; I reproduce here:
Hello PF folk.
If you believe the Dirac equation in curved spacetime, and you believe Spin(10) grand unification, then a Spin(3,11) GraviGUT, acting on one generation of fermions as a 64 spinor, seems… inevitable.
Also, it’s pretty.
And it’s up to you whether or not to take seriously or not the observation that this whole structure fits in E8. Personally, I take it seriously. Slides are up for a talk I gave at Yale:
http://www.liegroups.org/zuckerman/slides.html
Best,
Garrett
I am not certain whether it addresses Distler’s previous objections (as I am not certain whether the issue was even settled at that time– see here and here, which goes as far as I could follow. More (older) personal opinions can be found here, here and here in reverse chronological order).
Edit: I forgot to add. I do find the theory beautiful and interesting. I hope it can be properly tested.
Edit: Here are further links that are relevant to this post.
There is no “Theory of Everything” inside E8 by Jacques Distler and Skip Garibaldi.
Here is Distler’s blog entry on his paper.
There was a discussion of Distler and Garibaldi’s paper at Physics Forums some time ago.
There was also a discussion at n-Category Café some time ago.
October 30, 2009 at 10:13 am
“I am not certain”
Does that mean that you think it does, but are not sure?
October 30, 2009 at 3:34 pm
It just means that I have not reached a technical opinion. Nor I suppose I would any sooner. It is not my expertise.
However, I do have a subjective opinion — a matter of taste — that I like the approach. I do hope that his work receives appropriate analysis by experts. Previous objections made by you were extremely important. But I cannot follow the final conclusion, whether there was one at all. Again, “I am not certain” whether Lisi’s current investigations address those previous objections.
October 30, 2009 at 6:03 pm
“Previous objections made by you were extremely important.”
Important to whom? To Lisi? To you? To some unspecified set of “experts”?
As you well know, Skip Garibaldi and I ended up writing a paper (to appear in Communications in Mathematical Physics), formalizing those objections. Was that paper “extremely important”, too? If so, to whom?
As far as I can tell, nothing I have said has had the slightest influence on Lisi or his fans. Hence my puzzlement …
October 31, 2009 at 10:46 am
I have updated this post to include Distler’s paper and some other links.
To be clear: I am not “Lisi’s fan”. The only thing I am really fan is of the Star Trek series. (And Bach as my preferred compositor).
Evidently, “importance” is a relative quality…
I hope to have time and energy to follow this issue in more detail.
November 7, 2009 at 1:22 pm
Hi Christine,
I’ve looked at the references you provided and some of the statements made by Garrett and Distler et al and find it to be not much more than your typical theoretical cat fight. I hold no opinion either way as most any of this extends into things much greater than any knowledge I have or ever hope to. My only observation is that Distler’s argument is purely mathematical as Garrett’s theory stands to represent as well, with neither side coming across with any experiment whose outcome could lend credence to either of their positions. Perhaps naively Distler et al’s objections has me reminiscent of Von Neumann’s impossibility proof against hidden variables, which even though dismissed mathematically by Grete Hermann shortly after being published was regarded as the definitive last word on the subject fo more the 30 years, that until John Bell addressed in again.
In short, I find Garrett’ s theory to suffer the same problem as most if not all of the other so called TOE’s, as having a lack of any physical means that could support them as to distinguish it from other attempts. Although philosophically I’m an unashamed Platonist, when it come to science, even though I’m thoroughly convinced beauty reveals their being some truth to be discovered that coincided with it, which truth it serves to be is completely another matter. So even though Garrett or Distler may each feel they have passed the rigorous tests as proposed by Descartes, still one hurdle remains in being able to satisfy Bacon.
Best,
Phil
November 9, 2009 at 7:47 am
your typical theoretical cat fight
I do not understand this statement…
November 10, 2009 at 8:16 am
Hi Christine,
What I meant by it appearing as a typical theoretical cat fight, is seems to be what often takes place when any new theories are being proposed, where the detractors have more than revealing the truth, yet often the preservation of their own theoretical positions . Of course even when deciding physical evidence is predicted and presented many still refuse to find the truth it presents.
Best,
Phil
November 10, 2009 at 8:41 am
Well, I just do not understand why you say it is *my* typical cat fight. (Did you not mean to say *their* typical cat fight?).
November 10, 2009 at 8:47 am
Hi Christine,
I must apologize as I never intended it to be taken it was your fight, just strictly between the parties themselves.
Best,
Phil
November 10, 2009 at 8:55 am
No need to apologize, now that i understand what a “cat fight” is (in that context), it is pretty clear enough that you did not mean so say that I had something to do about it…
December 9, 2009 at 4:40 am
“Your typical X” is an English-language idiom meaning “a typical X”. Google “your typical” and you will see many examples.
December 9, 2009 at 7:57 am
Hi Mitchell
Thanks! I had no idea about such expression.
Christine