Explicit embedding of gravity+Standard Model in E8 (new Lisi paper)

[marcus]

http://arxiv.org/abs/1006.4908
An Explicit Embedding of Gravity and the Standard Model in E8
A. Garrett Lisi
14 pages. For peer review and publication in the "Proceedings of the Conference on Representation Theory and Mathematical Physics."
(Submitted on 25 Jun 2010)
"The algebraic elements of gravitational and Standard Model gauge fields acting on a generation of fermions may be represented using real matrices. These elements match a subalgebra of spin(11,3) acting on a Majorana-Weyl spinor, consistent with GraviGUT unification. This entire structure embeds in the quaternionic real form of the largest exceptional Lie algebra, E8. These embeddings are presented explicitly and their implications discussed."

As I recall there was a conference at Yale last October at which Garrett was invited to present a paper on this topic. I think the Yale 2009 conference was the one referred to here---on Representation Theory and Math Physics.

The way it works out, it seems like this "ToE" predicts a whole bunch of new particles which the LHC can find or not find. In effect, it does what theoretical physics is supposed to do, and is what any proposed new unification model is supposed to be---namely predictive and testable.

Some of what other particle theorists work on these days is not so explicitly predictive, and does not risk rejection by Nature--it's more along the lines of a mathematical pastime--or a "framework" of math with numerous different possible applications. But I don't think Lisi's is the only testable unification on the table. There is one that Hermann Nicolai presented last year---joint work with Kris Meissner---making, as I recall, explicit predictions which could be ruled out (or confirmed) over the next few years at LHC.

 

[dpackard]

How can a classical field theory like GR and a quantum field theory like the SM be unified in a single algebraic structure like E8? I guess this question applies to the GraviGUT step specifically. Is it merely that there is a spin-2 boson in the theory that matches the graviton, as is seen in string theory? I've never really understood how having such a particle really equates to a unification of QM and GR - for instance, how do the interactions of this particle reproduce something like the precession of Mercury's perihelion, or any of the other phenomena that required the GR modification to gravity? Anyone know?

On another note, doesn't this attempt at a TOE maintain the same background dependence issues that LQG people say plague other unification attempts like string theory?

I do like that he responds to Jaques Distler's critiques in this paper, thought I'll be interested to see if Distler himself finds the argument convincing (about how the mirror fermions gain extra mass and thus remain unseen, if I'm reading this correctly).

 

[tom.stoer]

Distler argues that E8 is not large enough to contain three fermion generations and that the existence of mirror fermions / non-chiral matter kills the model. As far as I can see this new paper does not really address these issues.

 

[MTd2]

http://golem.ph.utexas.edu/~distler/blog/archives/002233.html#more

Distler aswers and says he will present a talk next week with Garibaldi in which Garrett will also participate! Moderator's note: excessively long string of !'s deleted[/color]

 

[rhody]

Maybe this will be a High Noon moment...

See attached thumbnail...

Good luck to the guy whose name starts with the same first letter as Mr Cooper...

Too bad the original gunfight didn't take place at: 12:18...

Rhody...

 

[vacuumcell]

Maybe the post-Distler Garrett will be kind enough to discuss here at PF his thinking just as the pre-Distler Garret did.

 

[marcus]

Maybe this will be a High Noon moment...

!

Beautiful spot for a workshop on E8 and Lisi's unification idea! Banff. MTd2 thanks for posting the link to the workshop. The organizer is Joe Wolf, which says a lot. I will quote:

Banff International Research Station for Mathematical Innovation and Discovery

Structure and representations of exceptional groups

Objectives

"From Cartan and Killing's original classification of simple Lie groups in the 1890s, these groups have been understood to be of two rather different types the infinite families of classical groups (related to classical linear algebra and geometry); and a finite number of exceptional groups, ranging from the 14-dimensional groups of type G2 to the 248-dimensional groups of type E8. Often it is possible to study all simple Lie groups at once, without reference to the classification; but for many fundamental problems, it is still necessary to treat each simple group separately.

For the classical groups, such case-by-case analysis often leads to arguments by induction on the dimension (as for instance in Gauss's method for solving systems of linear equations). This kind of structure and representation theory for classical groups brings tools from combinatorics (like the Robinson-Schensted algorithm), and leads to many beautiful and powerful results.

For the exceptional groups, such arguments are not available. The groups are not directly connected to classical combinatorics. A typical example of odd phenomena associated to the exceptional groups is the non-integrable almost complex structure on the six-dimensional sphere S⁶, derived from the group G2. What makes mathematics possible in this world is that there are only finitely many exceptional groups: some questions can be answered one group at a time, by hand or computer calculation.

The same peculiarity makes the possibility of connecting the exceptional groups to physics an extraordinarily appealing one. The geometry of special relativity is governed by the ten-dimensional Lorentz group of the quadratic form of signature (3,1). Mathematically this group is part of a family of Lorentz groups attached to signatures (p,q), for any non-negative integers p and q; there is no obvious mathematical reason to prefer the signature (3,1). A physical theory attached to an exceptional group - best of all, to the largest exceptional groups of type E8 - would have no such mathematical cousins. There is only one E8.

Two years ago Garrett Lisi proposed an extension of the Standard Model in physics, based on the structure of the 248 dimensional exceptional Lie algebra E₈. Lisi's paper raises a number of mathematically interesting questions about the structure of E8, for instance this one: the work of Berel and de Siebenthal published in 1949, and Dynkin's work from around 1950, gave a great deal of information on the complex subgroups of complex simple Lie groups. For example, they independently showed that complex E8 contains (up to conjugacy) just one subgroup locally isomorphic to SL(5,C) x SL(5,C). For Lisi's work, one needs to know about _real_ subgroups of _real_ simple groups: which real forms of SL(5) x SL(5) can appear in a particular real form of E8? These are subtle questions, not yet completely understood. A mathematical study of these questions is interesting for its own sake, and may provide some constraints on the structure of the physical theories that can be built using E8.

The goal of this workshop is to introduce mathematicians to these physical ideas, and to describe much of the recent mathematical work on the exceptional Lie groups."

http://www.birs.ca/birspages.php?task=displayevent&event_id=10w5039

 

[rhody]

This is off topic. I have two co-worker friends who have been to Banff and they both said it was one of the most beautiful places they had ever been to. How does it stack up next to Maui ?
I don't know, haven't been to Banff, but can say that one secret hidden black lava beach on Maui, near Hana (thanks to a mutinuous tour guide back in 2006, hehe)
was the most beautiful unspoiled beach I had ever seen and for the local's sake, hope it stays that way.

Rhody...

 

[garrett]

Marcus: Thanks for starting the thread.

Rhody: I haven't been to Banff yet either -- I'm curious too.

vacuumcell: Sure, I can answer brief questions here -- preferably focusing on what's in the paper, which I'm happy about.

 

[marcus]

This is off topic. I have two co-worker friends who have been to Banff and they both said it was one of the most beautiful places they had ever been to. How does it stack up next to Maui ?
I don't know, haven't been to Banff, but can say that one secret hidden black lava beach on Maui, near Hana (thanks to a mutinuous tour guide back in 2006, hehe)
was the most beautiful unspoiled beach I had ever seen and for the local's sake, hope it stays that way.

Rhody...

Rhody, it is not only one of the most beautiful spots in N. America judging from this:
http://www.birs.ca/images/birs/publications/birs_brochure_dec09.pdf

it is also (according to Joe Wolf) where they regularly have some of the best mathematics workshops in the world. The only comparable venue being Oberwolfach in Europe.
I took a course from Joe Wolf around 1970---it was a lecture/'seminar on Group Reps and QM he taught with a guest expert from Harvard (George Mackey). Wolf was a callow youth at the time, quiet gangly reserved amazingly smart. Now 40 years later, he looks a bit grizzled:
http://math.berkeley.edu/index.php?module=mathfacultyman&MATHFACULTY_MAN_op=sView&MATHFACULTY_id=146
I'll get what he says about the Banff workshops:

==Wolf on Banff==
"The Banff International Research Station plays an important role in North American science. Its programs bring Canadian, Mexican, and U.S. researchers into contact with European and Asian researchers, for scientific programs at the highest level. The only comparable facility in the world is the Mathematisches Forschungsinstitut Oberwolfach in Germany."

 

[MTd2]

Tommaso Dorigo posts about Garrett's new paper on his blog:

http://www.scientificblogging.com/quantum_diaries_survivor/garrett_lisis_new_e8_paper

 

[humanino]

I've never really understood how having such a particle really equates to a unification of QM and GR - for instance, how do the interactions of this particle reproduce something like the precession of Mercury's perihelion, or any of the other phenomena that required the GR modification to gravity? Anyone know?

But have you ever really understood the problem, at all ? Why do you believe there is a problem in unifying GR with QM ?

In fact, it is published and well known : perturbative quantum gravity works fine, it just happens not to be renormalizable. That means, at any finite energy we need to perform loop calculation up to a given order, and fix the parameters using a finite number of experiments. As energy increases and more loops are required, we will get more parameters until our effective theory has more parameters than we have measurements, and then we loose predictivity.

At low energy, we can compute first quantum corrections, and they are well-behaved. For the specific problem of the perihelion, it was first published in
"Quantum Theory of Gravitation vs. Classical Theory"
Iwasaki, Prog. Theor. Phys. 46, 1587 (1971).

For a more recent review, please check
Quantum Gravitational Corrections to the Nonrelativistic Scattering Potential of Two Masses

So please, re-think about it. It was done, it works fine, and it has nothing to do with finding a well-behaved high-energy completion of quantum gravity.

 

[marcus]

MTd2, I see that Tommaso got into playing with E8 using that graphic software Garrett put on line.

Another of the organizers is David Vogan (MIT) who was one of those who analyzed E8.
http://www.boston.com/news/globe/he...07/03/26/his_mind_is_on_the_eighth_dimension/
http://www-math.mit.edu/people/profile?pid=286

I have a different take on things from people like Distler. There are people who like to simplify their lives by declaring "This cannot work! It cannot be the Holy Grail!" and giving half a dozen reasons.
To me, if an idea makes testable predictions and is, at the same time, mathematically interesting, that says a lot. If you have Joe Wolf and David Vogan looking at it, there is probably something there--a scent of game.

The best mathematicians are like dogs that can smell when an idea is fertile. They make their living by having a good intuitive nose for possibilities. Jacques Distler can swear on a stack of Jacksons that something must fail, but he doesn't own the future of physics---we just have to see.

Oberwolfach (the European version of Banff) is where Matilda Marcolli (Caltech) just had that workshop on combining the Noncommutative Geometry Standard Model with LQG (Ncg + Lqg).

 

[MTd2]

Garrett, let me see if I understand what you say. You substitute the concept of chirality by asymmetry of the particles and its mirror image by an existing particle. They are just not seen because they might be very very heavy, right? But the problem is that the other 2 generations are not there and that the triality is just a hint. So, no TOE yet...

 

[garrett]

MTd2: Correct.

 

[MTd2]

Let me see if I get this. Triality does something like this:

C - A - B -> 3 gen

B - C - A -> 2 gen

A - B - C -> 1 gen

| | |

fer mir bos

Triality exchanges the matrix elements. It could be presented by a matrix operator, where i=j you have bosons and for i=/=j you've got bosons. If written in full form, it would be like an operator that fastly exchanges matrixes like CKM.

 

[garrett]

MTd2: Yes, and if you can figure out a way to formulate that concretely and naturally, there might be a prize in it of some sort.

 

[arivero]

Hmm, related to CKM, an important point is that it implies that mass eigenvectors are not charge eigenvectors.

 

[MTd2]

I was staring at the table I made yesterday, and I had this weird idea a few hours ago. Going from left to right, you'd see the list of energy shells from outside from inside.

The third generation would be a "nucleus", formed by fermion and mirror, surrounded by a boson "cloud". This is the heaviest set, due to the proximity of the fermion and anti fermion.

Second generation are two nucleus, "covalently" bound by the boson "cloud".

First generation fermion and mirror are free, but given that the mirror is short lived, you just see the the fermion.

Now, we see that maybe the only thing that Garrett was missing was screaming at his face all the time: the chiral force!

Triality, like the CKM, is the transition probability, this time between binding states.

 

[BenTheMan]

How does this new work evade Distler's no-go theorem?

 

[MTd2]

it doesnt. In my opinion,the only way to reproduce the sm is to calculate the bound states between each particle with its mirror, and see if the allowed states gives away the remaining generations. Other than that, i see no solution to where to hide the mirror particles neither what to do with only one generation of particles. Of course, to accomplish what i described, garrett must show that there exist a kind of chiral force.

 

[BenTheMan]

it doesnt. In my opinion,the only way to reproduce the sm is to calculate the bound states between each particle with its mirror, and see if the allowed states gives away the remaining generations. Other than that, i see no solution to where to hide the mirror particles neither what to do with only one generation of particles. Of course, to accomplish what i described, garrett must show that there exist a kind of chiral force.

If this is true, how can it be honestly called an ``explicit embedding''?

Let me rephrase:

Whenever I give a talk about string theory, I always say ``If some string theorist tells you he can get the standard model out of string theory, your first question should be `What do you mean be Standard Model?' ''.

So I ask: what does Lisi mean by ``standard model''? Does he mean SU(3)xSU(2)xU(1)? three generations with hierarchical masses? order one top quark yukawa coupling? CKM angles and phases?

If he can't explain these things with E8, the thread title should be changed to say ``standard model-like embeddings'', you know, for honesty's sake.

 

[MTd2]

Well, I read his paper, and this new one, at least for me, he seems to be pretty clear that he is clueless about "what he seems to be the standard model", and all your subsequent questions.

In the text he says he got one generation, but he is clueless on how to get all 3. He talks about that the reps of the mono generation SM, the mirror mono generation SM and bosons are extremely similar and works alright, if the SM had only 1 generations. Hints about a certain triality, in a way that mirrors and bosons could be somehow transformed into 2nd and 3rd generation. But, again, this time he was clear in the text, at least for me, that this is an aesthetic argument.

As for him being honest or not, I am waiting him answering if the generations of SM can be built by bound states of a mysterious chiral force... I mean, I invented this solution in the last post, so it is not something that he wrote. :S

 

[garrett]

Ben: Good point. The abstract makes it clear that it is one generation that is being explicitly embedded in E8 -- I would have added that to the title, but it was getting too long as it was. How to get three generations is still an open question, and I can't even rule out MTd2's wild ideas.

 

[BenTheMan]

Can you estimate the yukawa couplings at all? Or, what sets the yukawas? I'm guessing that the only real free parameter you have floating around is the gauge coupling, so it should come from alpha and factors of pi?

 

[BenTheMan]

As for him being honest or not, I am waiting him answering if the generations of SM can be built by bound states of a mysterious chiral force... I mean, I invented this solution in the last post, so it is not something that he wrote. :S

Presumably you'd need MORE matter to make bound states, right? MORE matter is exactly the problem he's facing, so I don't see how alluding to bound states will help him.

 

[MTd2]

Presumably you'd need MORE matter to make bound states, right? MORE matter is exactly the problem he's facing, so I don't see how alluding to bound states will help him.

Atoms are bound states of protons, neutrons and electrons, right? So, generations would be atoms of fermions and mirror fermions.

 

[BenTheMan]

Atoms are bound states of protons, neutrons and electrons, right? So, generations would be atoms of fermions and mirror fermions.

Except technicolor doesn't work :)

You'd have to show how to get some gauge group with rank larger than 8 out of a gauge group with rank 8, which is not possible. Either you have to sacrifice one of the SM gauge groups, or you have to sacrifice the SO(3,1) embedding. In the former case, or you have to consider some non semi-simple group (i.e. E8 x G, where G is something else). In the second case, you might as well start building weakly coupled heterotic string models, which DO give you three generations, etc.

 

[MTd2]

Wasn't that spin(3,1)? I didn't see SO(3,1).

 

[MTd2]

Garrett, the boson that communicates left and right is the frame higgs, right? In the case above, the boson responsible for biding and building generations would be the frame higgs. I mean, your fermions and mirror fermions are related by that boson, right?

BTW, this is indeed similar to a kind of technicolor, but of a kind of which some versions were not ruled out:

http://en.wikipedia.org/wiki/Technicolor_(physics)#Walking_technicolor

But notice that I think these are vastly different models from yours. To be sure, you should calculate the stuff.

 

[BenTheMan]

MTd---to get strong coupling dynamics you need another gauge group which can become strongly coupled. If Garrett is intent on maintaining his embedding pattern into E8 (and I can assure you he is), then your suggestion is right out.

 

[MTd2]

the mirror has a strong sub group!

 

[MTd2]

Schedule for talks are available:

http://www.birs.ca/workshops/2010/10w5039/Programme10w5039.pdf

and Garrett twitted his arrival in Banff 1 hour ago.

http://twitter.com/garrettlisi

This conference is clearly centered around Garrett. He gives 3 talks, all of them at night, after dinner.

 

[jal]

I’ve been looking over the abstracts at “Structure and representations of exceptional groups”, July 4–July 9, 2010.
http://www.birs.ca/workshops/2010/10w5039/Programme10w5039.pdf

The LHC is producing a Perfect Liquid. It must be describable by E8.

If E8 is the Perfect Symmetry that can explain the “new particles” that will be postulated, and calculated to have come out of the Perfect Liquid as it breaks down, (expands), then this would signify that the Perfect Liquid also exist in multiple dimensions, (greater than three).

This would imply that the initial universe existed in more than the present three dimension.

Therefore, it also imply that “black Hole” exist in a multidimensional universe, (more than three), since E8 would be the Perfect Symmetry that would also apply for describing the Perfect Liquid in a “black hole”.

Interest approach that is worth investigating in case “new particles” need explaining.

jal

 

[BenTheMan]

The LHC is producing a Perfect Liquid. It must be describable by E8.

what makes you say this?

 

[MTd2]

Group photo is out.

Garrett = Bruce Willis!

http://temple.birs.ca/gallery/10w5039/groupphoto

 

[marcus]

Garrett and Joe Wolf are the two that happened to be wearing sunglasses. The others are squinting in the bright Canadian Rockies sunlight.
Everybody is grinning like they have been having a good time. (The math must have been good, only thing that would make 30 mathematicians grin like that.)

 

[rhody]

On garrett's twitter (public page):

Oh, and Hopping Fish admitted, grudgingly, that the algebra of gravity and the Standard Model, with one generation of fermions, is in E8.

If this is an inside joke, are we speaking of the now infamous, Showdown at High Noon, Jacques Distiler, or some other as yet under cover conference attendee ?

Rhody...

 

[marcus]

On garrett's twitter (public page):

Oh, and Hopping Fish admitted, grudgingly, that the algebra of gravity and the Standard Model, with one generation of fermions, is in E8.

If this is an inside joke, are we speaking of the now infamous, Showdown at High Noon, Jacques Distiler, or some other as yet under cover conference attendee ?

Rhody...

http://en.wikipedia.org/wiki/Garibaldi_(fish )

 

[MTd2]

Isn't Distler the guy with grey beard at the same row of Garrett?

http://temple.birs.ca/gallery/10w5039/groupphoto

 

[marcus]

Rhody, as far as I know (I haven't kept track of details and have no source of info besides links that you and MTd2 provide) Jacques was not supposed to attend the workshop. There was no "high noon" with Garrett and Jacques. That was only a kind of spin sensation that we got from Distler's blog. Garrett did not mention it or play it up after it was mentioned.

The serious math content is what you could think of as subjecting the Lisi E8 idea to scrutiny and stress-test. This was meant to include an associate of Distler, named Skip, giving a paper. If you look at the schedule of talks you will see the one.

As far as I can tell what they did at the Banff workshop is very much in the age-old tradition of high-level mathematics. After an idea has gotten notice, the experts in that special subject will get together in seminars/workshops and really grill it and probe it and check it out. Sometimes when somebody thinks he has proven a theorem, his colleagues will find a hole or a gap in the proof, and often he takes a few more months and is able to fix it, and maybe finally the theorem may pass muster. That's how they work, oftentimes. You've probably seen examples of this, like, "mathematician's culture" operating. It is really good that Lisi E8 idea is getting this kind of serious traditional reception.

Anyway this is how I interpret the little news I have. I think it is extremely constructive to have workshop with really top people looking carefully at the idea. And who knows the ultimate outcome? There are different degrees of generality and applicability to math models and to theorems. In the end nobody loses. Knowledge is advanced for everybody.

The twitter message was funny!

It sounded like a reference to an Inuit folktale.

 

[marcus]

Isn't Distler the guy with grey beard* at the same row of Garrett?

http://temple.birs.ca/gallery/10w5039/groupphoto

MTd2, I didn't see any mention of Distler being there. Am I missing something? Was he on the list of participants?

I never saw Distler so I wouldn't necessarily be able to recognize him in a group photo. I've just seen random snapshots like this:

http://www.hep.princeton.edu/~mcdonald/nov1702/
http://zippy.ph.utexas.edu/directory.html

In any case Distler is not the important person here. The guy who was supposed to deliver the antithesis is a mathematician called Skip Garibaldi. He is the one we should be looking for in the picture. Distler is just an extraneous string personality with a blog, in this situation. He might not even have been at the workshop.

Here is Skip:
http://www.mathcs.emory.edu/~skip/home/Skip_Garibaldi.html

(young, full professorship in the math department, with a named chair "Winship distinguished professor", looks like a bright happy camper---good person to have doing your constructive crit, from the looks. not a mean-spirited old snark-puss.)

Do you see Skip in the group picture?

Here's my wild guess. If you start at Garrett, in front and to our left is this guy with a yellow shirt, and in front of him and to our left is this young guy in a pale blue work shirt. He is grinning---a big row of front teeth. Draw a straight line from Garrett, through the head of the guy with the yellow shirt, to (who I think is) Skip.

*Actually the guy you mentioned, in the same row as Garrett, with the grey beard, could be David Vogan (MIT math department) co-organizer of the workshop, with Joe Wolf (UC Berkeley math department).
http://www.boston.com/news/globe/he...07/03/26/his_mind_is_on_the_eighth_dimension/
Vogan is one of the giants of Naughties mathematics. His team analyzed the structure of E8 and the computer printout would have covered the Island of Manhattan, maybe even two times over. It was a big computer job. "Naught" means zero and "Naughties" is slang for the 2000s, the decade that we are just barely out of. We are now in the "Tens" or "Teens" decade of this century.

http://www.birs.ca/birspages.php?task=displayevent&event_id=10w5039

To my limited ability to view history, this workshop is something of a landmark. Everybody looks happy to be there, including Skip Garibaldi (whose work putting Lisi-E8 on trial will be a valuable contribution however it goes) and Garrett looks well-satisfied.

 

[rhody]

Thanks Marcus for clearing that up, if you click on the link to the picture of the conference again, it enlarges for a good clean view of everyone. I see Skip Garabaldi as you suggest, blue shirt, second row, big white teeth smile, on the left.

Vogan is one of the giants of Naughties mathematics. His team analyzed the structure of E8 and the computer printout would have covered the Island of Manhattan, maybe even two times over. It was a big computer job. "Naught" means zero and "Naughties" is slang for the 2000s, the decade that we are just barely out of. We are now in the "Tens" or "Teens" decade of this century.

I downloaded the http://www-math.mit.edu/~dav/E8TALK.pdf" a year or two ago. Interesting story. I couldn't help but notice a label that keep my interest about the difficulties in deriving the roots for E8. It read in part: "RTFM (beginning on: page 25 of slide presentation)" -> or Read the blanking Manual ! At least they kept their wits and sense of humor about them after taking on this challenge. Look at page 4 of the slide talk (group pic) and second from left is David Vogan I am guessing, and in the Banff pic he would be in the back row second from the right in light blue shirt, beard and glasses.

They dedicated the work to fellow team member: Fokko du Cloux who passed away, November 10, 2006. 1/8/07 9 A.M. Finished writing to disk the character table of E8.

It was a touching story. I am surprised no one posted it on PF. I apologize in advance if they did and I missed it.

That's my story and I am sticking to it. lol.

Rhody...

 

[marcus]

Garrett says he thoroughly enjoyed today's talk by Skip G. Now since the workshop has the whole Wednesday afternoon off, he's going for a hike in the mountains. http://twitter.com/garrettlisi/
(specifically http://twitter.com/garrettlisi/status/17966854102 )
The talk by Skip, 10:30-11:30 local time, was titled: There is no (interesting) ‘Theory of Everything’ inside E8.
I tend to reserve judgment on such headline claims, but it clearly signals the talk's main direction of effort.
After that there was lunch and then the long break for the rest of the day. Garrett gives his third 90 minute talk tomorrow evening after dinner (Thursday 19:30-21:00) concluding the workshop.

 

[marcus]

Funny mountain climbing story more or less realtime via http://twitter.com/garrettlisi/
Roberto Percacci (Asymptotic Safety approach to joining gravity+standardmodel) proposed climbing Mt. Rundle.

==quote==

Just returned from an amazing climb up Mt Rundle with Roberto Percacci. Fantastic day. I'm totally wiped.Me: "So, how high are we climbing?" Him: "3000" OK, looks pretty steep from here, but I think I can do that. METERS! HE MEANT METERS!Twenty feet from home, with my legs like cement, he tells me "yes, I was in a movie about mountain climbing." Nice. Could have warned me.

====
(about 9 hours ago via web, which I guess would have been around midnight local time)

Percacci is the guy standing next to David Vogan at the end of the back row.

 

[BenTheMan]

Is this facebook or is this a forum where people discuss physics?

Because I can't really tell...

 

[atyy]

In any case Distler is not the important person here. The guy who was supposed to deliver the antithesis is a mathematician called Skip Garibaldi. He is the one we should be looking for in the picture. Distler is just an extraneous string personality with a blog, in this situation. He might not even have been at the workshop.

Garibaldi and Distler are co-authors on http://arxiv.org/abs/0905.2658

 

[unusualname]

Is this facebook or is this a forum where people discuss physics?

Because I can't really tell...

I agree, too much fluff going on in this thread. Lisi proposed an embedding of the Standard Model in E8, media went nuts because they had an angle on a "surfer" guy solving the mystery of particle physics, Distler posted a well-reasoned rebuttal which turned out to be pretty much correct. The positive result was a lot of people got interested in E8 and real embeddings again, this conference enables some of the mathematics to be discussed in a proper environment.

Nothing worthy of so much comment really. I didn't see the media going nuts when Connes' proposed a solution to the standard model based on attaching a discrete structure to spacetime, or when Verlinde proposed his entropic model for gravity earlier this year. (Incidentally, I don't see Distler so quick to comment on those ideas in his blog, maybe he's a little wary after getting an earlier argument on CDTs wrong)

I think Jaques Distler is secretly happy about his high profile resulting from the incident, even though he claims otherwise, but he's not just some "extraneous guy with a blog", you may dislike his personality, but his physics/mathematics ability is extraordinary.

If Lisi didn't keep claiming to have the embedding of the standard model he wouldn't get so much criticism either (I think he mistitled his recent paper, even he agrees), he should be happy that his work has aroused so much interest and some real mathematics has grown from it, and I wish him the best of luck.

Still, if those "mirror fermions" show up we'll all have to hail the "surfer saviour" (Distler's term).

Cvitanovic has a nice quote in the http://www.cns.gatech.edu/GroupTheory/index.html of his Group Theory book (p 242): "to a religious temperament, E8 is the great temptress"

 

[dpackard]

If Lisi's theory is unable to produce the three fermion generations, then Garibaldi is correct and the one generation SM embedded in E8 isn't very interesting. So clearly this should be Lisi's future direction if he wants to stick with the E8 idea. So there isn't much of a controversy or disagreement anymore is there (on the physics itself, nevermind the circus surrounding it)?

 

[marcus]

If Lisi's theory is unable to produce the three fermion generations, then Garibaldi is correct and the one generation SM embedded in E8 isn't very interesting. So clearly this should be Lisi's future direction if he wants to stick with the E8 idea. So there isn't much of a controversy or disagreement anymore is there (on the physics itself, nevermind the circus surrounding it)?

That's basically the right kind of statement, except you have the tenses wrong (which misrepresents the present state of knowledge and interest).

Lisi's theory is not a fixed object. So far Lisi's theory only finds one fermion generation. We cannot say, as you do, "Lisi's theory is unable..." we can only say that it "has so far been unable".
The issue is whether the theory is interesting to work on.
We don't know the future of research in mathematical physics.

The basic fact to focus on, at this point, is that some worldclass people think it is interesting enough to have a select workshop on it. These are potential contributors to the theory.
Given the reputations and track record of the people at the workshop, it would be arrogant for any of us to pretend we can call the outcome.