Garrett Lisi has a new paper, “An Exceptionally Simple Theory of Everything.” Many people seem to think that I should have an opinion about it, but I don’t. It’s received a good deal of publicity, in part because of Lisi’s personal story — if you can write an story with lines like “A. Garrett Lisi, a physicist who divides his time between surfing in Maui and teaching snowboarding in Lake Tahoe, has come up with what may be the Grand Unified Theory,” you do it.
The paper seems to involve a novel mix-up between internal symmetries and spacetime symmetries, including adding particles of different spin. This runs against the spirit, if not precisely the letter, of the Coleman-Mandula theorem. Okay, maybe there is a miraculous new way of using loopholes in that theorem to do fun things. But I would be much more likely to invest time trying to understand a paper that was devoted to how we can use such loopholes to mix up bosons and fermions in an unexpected way, and explained clearly why this was possible even though you might initially be skeptical, than in a paper that purports to be a theory of everything and mixes up bosons and fermions so casually.
So I’m sufficiently pessimistic about the prospects for this idea that I’m going to spend my time reading other papers. I could certainly be guessing wrong. But you can’t read every paper, and my own judgment is all I have to go on. Someone who understands this stuff much better than I do will dig into it and report back, and it will all shake out in the end. Science! It works, bitches.
For a discussion that manages to include some physics content, see Bee’s post and the comments at Backreaction.
Jacques,
My main point was that I am doing what I can to try and improve the signal to noise ratio here. Insulting people generates loud noises that destroy usable signals. You and others should stop doing this, and I’m going to keep pointing this out to you until you do
Peter is going to increase the signal-to-noise ratio by providing absolutely no signal, nor physics, nor insights to into represention theory, nor comments on group theory, nor defense of lisi’s over-hyped proposal. Peter is going to increase the signal-to-noise ratio by ranting against those who actually provide a signal–a simple, beautiful description of the math underlying the physics.
Thanks to Distler for the illuminating posts pertaining to physics which have eduated all who have listened, including, eventually Lee Smolin.
Thanks to Peter for being not even wrong again.
Peter is the one making the contentless, snarky posts. We don’t need to wait for the LHC to decide this. Simply read his above comments, and his below comments, I would hypothesize.
Peter,
Since you have stated unequivocally, that you have no interest in the substance of the discussion at hand, I, in turn, will state unequivocally that I have no interest in your advice on the form that discussion should take.
If you want to improve the signal/noise ratio here, contribute some “signal.”
And, having contributed several comments-worth of noise by responding to you, that’s the last I will have to say on the matter.
Jacques,
As usual, you misquote and misrepresent everything I write. Just one example:
“I’ll be interested enough to try and follow the discussion and try and learn something” is
rather different than
“you have stated unequivocally, that you have no interest in the substance”
but I suppose your misquoting in bold face of people you discuss things with is a separate problem, one that is less serious than your insistence on insulting them.
Perhaps I can help resolve confusion, just in case anyone is, by digressing. The PS model has chiral fermions (so P Psi neq Psi) in the fundamental rep and has a left-right symmetry (under P the Langrangian looks the same). The SU(2)_R group factor may be broken to a U(1) (isospin) via a Higgs in the fundamental representation of SU(2)_R acquiring a VEV. (Maybe when we are seeing this referred to as a vector model somewhere above, it is referring to this Higgs being in the fundamental representation of the SU(2).) Consequently, the L-R symmetry is now broken. However, the fermions were always chiral.
respectfully, BL
Lee, the insults and harsh tones, the irrelevant comments etc., are just part of the territory. With respect, I have to say that I find equally distracting those interludes about the moral character of yourself and your colleagues, including dark hints about their hidden motivations. Since we had so many productive exchanges in person, I tend to believe this is one of this instances where the medium allows only shallow conversations and is prone to produce misunderstandings. This is a shame because there was a time I believed this medium to be ideal for an informal discussion of physics. Maybe there is still a way of doing just that, I’d appreciate your thoughts sometime, but in person.
In the meantime, the only productive thing I have to say is urging you and Garrett to submit your work for publication. The best place for this sort of work is probably the journal of high energy physics, where you are likely to get substantive comments. If and when those papers are accepted for publication, the time would be appropriate to talk about them to journalists, though I would still avoid a certain, how shall I put it, excitable, section of the media.
Best of luck,
Moshe
This is great stuff. Really fun. I imagine some of my arrogant, dismissive Prof when I was an undergrad beating each other with sticks! Hit him again!
The physics is fun too. I don’t have the ability to judge it wrong, but Lisi work has contributed to advancing knowledge, (admit it, you learned something new because of it). That what it’s all about.
Whether or not Lee comes back, I would appreciate some informed comment on the construction in his paper, as mentioned in comments 82 and 83. I give a one-paragraph synopsis here. This pertains to the questions he asks in 190:
“Even if there is some truth to Distler’s argument, is the result the end of Lisi-like proposals or are there alternatives which evade it? For example, by going to the complexification? Or might it be that Lisi’s proposal works for the Euclidean spacetimes but not for lorentzian? Might it be that it only works if only part of the lorentz algebra is gauged, as in the Ashtekar or Thiemann formulations?”
P.S. to onymous, comment 186: I had in mind Higgsless braneworld models, but it turns out that it’s Kaluza-Klein modes which restore unitarity there.
Moshe,
I share your pessimism. Over the years, I have hosted hundreds of technical discussions on my blog, some amicable, some contentious, But almost all of them can be said to have reached a satisfactory conclusion.
In this instance I think the root of the problem is the lack of a common language. If we can’t agree on the definition of common terms, like “chiral fermions” or a “vector-like theory,” then it’s hard to see how the discussion can ever converge.
One might have thought that my reduction of the issue to a clear-cut mathematical question in representation theory, a question that must have a yes-or-no answer, would have led to a way out of the impass.
That was clearly wrong.
Mitchell Porter, quoting Smolin, wrote:
There are many other problems with Lisi’s and Smolin’s idea. But I don’t see the point of discussing them, when I can’t even get an admission that I am correct on this point.
If there’s some variant of Lisi’s proposal which evades this difficulty, let Smolin or Lisi write it down. Then we can discuss it.
But before getting to that step, they will first have to understand the failings of their current proposal. That, they have stubbornly resisted doing.
Jacques, you definitely try to, and do, push things forward here, which is very good and appreciated. I disliked the tone of your first post, but looking at it from the perspective of muddy atmosphere in 85% of posts here (PW…), I accept it as a feature (though still not endorsing such).
I don’t think that using “they” when referring to Lisi and Smolin (in your last post) is a good thing. No one wants to form “gangs” here. Garrett has post only once here clarifying his relations with media, and this seems to be a smart thing to do.
Lisi hasn’t stubbornly resisted your argumentation, as you suggested in the last sentence. He admitted that his “PS” model is a left-right symmetric, not a chiral one. You’re point is that this ends here. No response on that from Garrett.
So:
There was a “humble” proposal for a Theory of Everything, which was described as “fabulous” by some well-known physicists, hence the media frenzy.
There is now a proposed mathematical argument stating that the proposal, in the form stated, is mathematically incorrect. The people claiming that the theory is fabulous have tried to counter the argument, so far without success. As of now, the argument stands, and the proposal seems mathematically incorrect.
However, the people claiming that the theory is fabulous pretend to be nice and friendly and ready to admit mistakes and apologize — although they have never apologized for suggesting that a theory is “fabulous” without going through the details of the theory beforehand. But since these people are nice and friendly, we should all agree with them that the theory is fabulous, shouldn’t we? Whether it is correct or not does not matter, since they are nice and friendly…
I’m sad… and sometimes desperate with the state of theoretical physics (and not because of string theorists). Or perhaps it’s just blogs that are distorting reality.
Jacques, a few years ago, when CV started out, we had a nice discussion of what can be done using this medium, following Clifford’s post I believe. I thought at the time that we can have some generalized group meeting going, where people at all levels, and at different locations, can participate in the many entangled conversations that result from an interesting blog post. It is only with some disappointment that I conceded some time ago that this is not happening, at least not at the scale I thought it would.
I do think your blog is the only exception, and it is of great value to us pros, more than once a printout of your blog post was the starting point of a group meeting I attended. I enjoyed a few discussions with you there, and more often learned a lot without commenting. I would have thought that by now that would be much more wide spread and more people would participate, but the discussion above in particular is not encouraging, and is very frustrating to watch for the reasons you mention. I can’t imagine anyone wanting to get into this sort of quagmire where being correct is simply irrelevant, and the conversation descends into irrelevancy almost immediately…
Lee’s post #190 is an Orwellian masterpiece, starting out with “the points I made about Pati-Salam stuck.” Distler has already pointed out that this statement is flat out wrong. Readers who understand chirality can easily verify this by rereading the relevant posts. Those who do not will have to take my word for it or try to find a local expert to ask. Lee asks why anyone should take me seriously. Umm, because you can check that what I have said is correct? The real question is why anyone still takes Lee seriously. Perhaps they don’t.
Then we have the statement that Jacques changed the subject. False again. He may have given up in frustration, but he certainly didn’t change the subject. He’s stuck to those damn non-chiral fermions through thick and thin. Next comes a demonstration that Lee still hasn’t understood the point of Distler’s posts and my small clarification. Finally we have a lot of blather about unprofessional behavior and insults and anonymity. Let us examine who is insulting and unprofessional. Lee, in his post #90, posted before Jacques had chimed in at all, says “Distler does not point to a specific step…” polite, but wrong. Then “Distler was largely wrong in his previous post…” again false and less polite. Then more blather about “one-sided arguments” and “nasty hardball” all obviously aimed at Distler. I ask you, was that a polite and respectful way to start the discussion? He outright attacks Distler, and then turns around and complains when Jacques responds in kind. Amazing! I really think Lee is in the wrong business. The Republicans could use someone with this kind of Roveian ability to twist the truth.
As to Lee’s paper, I have in fact read it. I read it before making my comment about “lipstick on a pig.” That was the simplest way I could capture the essence of what was going on to a non-expert audience. I didn’t respond to Lee earlier for the same reason that Jacques has stayed focused on one point. It only opens the door to obfuscation. If Lee won’t agree that Distler is correct about a well-defined mathematical statement, just imagine where we would get if the discussion were opened up to included additional topics. However, even non-experts might be entertained by reading the section of Lee’s paper on fermions. It consists of a picture, a few vague words about “disordered locality” and “Planck scale wormholes” and a couple of references to the literature. There are no equations, really nothing to get one’s hands on that could be said to be definitely right or wrong. We could debate that, and other aspect of Lisi’s proposal forever without coming to a conclusion. Of course getting Lee to admit that Lisi’s model doesn’t have chiral fermions may also take forever.
This discussion is fascinating on many levels and I wish thank you all for it. When your career is based on your personal credibility, you take a great risk in speaking freely. I applaud the courage of those of you who determined to make this public forum _work_.
We share a common believe that mathematics is the key to comprehending existence, but few of us have the skills to find our way in this space without a map. For me, it is a rare privilege to observe the workings of this sausage factory.
I am sure(?) Garrett would have found some value in the exchange between Jacques and Lee’s?
Like a previous commenter “I sensed” that when they continued in face of all the rhetoric, there was work actually being done that we could witness.
Science being talked by scientists.
The blog is still a useful function “no matter how much the detractors” say there isn’t.
The push to persevere, was itself a good focus, and to come out with mathematics explained in a environment “more suitable to that expression,” was explained.
From that point, I think one could again start I am sure, and if Cosmic Variance can implement some of that mathematical expression suitable for the continued discussion, then I would see no reason why it couldn’t continue here.
Observer said:
My impression (I would be happy to be corrected) was that he meant those words in the sense of Lee Smolin’s post #90, confusing the fact that the Pati-Salam model is parity-invariant with whether or not is it is chiral, believing — as Lee asserted in post #90 — that it is vector-like (non-chiral), but that chiral fermions would emerge, once parity is spontaneously broken.
If that’s not what he meant, if he really does agree that his theory is non-chiral (something which is not miraculously “cured” by spontaneous symmetry-breaking), then that’s another matter, and — you are right — I should not lump the two together.
That he hasn’t responded is, perhaps, to his credit. We’ll see what the promised revision of his paper holds.
Moshe said:
Which is why I still hold out some hope for this medium.
Over in Mathematics, there are now several such blogs, with very high quality content and lively, high-level discussions. So it’s not impossible.
But the physics demi-monde, some of whom we have witnessed in action in this thread, present some unique challenges…
Hence my stated (and much-ridiculed) reluctance to get involved in this Lisi affair in the first place. I knew it would end up like this.
…it’s not “irrelevant” to this point.
Jacques, we learnt of your reluctance some time ago about this. I am glad you continued. And, I am Glad Lee continued as well.
We’ll see if Garrett responds “maybe” before then, if he’s not off somewhere snowboarding? 🙂
Hello H-I-G-G-S – What I really want to understand is section 2 of Lee’s paper (just about gravity and Yang-Mills, no fermions), with respect to (1) CM theorem (2) his introductory remark that “these approaches [may] give rise to consistent finite quantum theories”.
(1) He seems to start with a theory of spin 1 fields with global symmetry G, considers perturbations about a particular classical solution, and ends up with a theory of spin 1 fields coupled to spin 2 fields, with a global symmetry of SO(4)+H. Neither before nor after violates the CM theorem, but it still seems strange, so I would like to somehow look at this through the lens of the original CM paper, even if only to clearly see which of their assumptions do not hold, but I’m having some trouble with putting it all into a common language, not least because these are topological theories.
(2) This line of thought may just lead back to previous discussions about LQG: perturbative gravity is not renormalizable, even if you throw in Yang-Mills fields; LQG is nonperturbative, but does it make a difference, etc.
Jacques Distler said
I didn’t know what a “demi-monde” is, though I suspected Jacques was saying something rude in French, so I looked it up in a dictionary. And sure enough “demi-monde” means “prostitute”. So, Jacques, would you care to explain why you chose to deride your targets in this particular manner.
Demi-monde has more than one meaning:
a group of people considered to be on the fringes of respectable society
One of the reasons imo that there isnt more technical traffic on this particular subject at Musings is that its fairly definitive. Theres not much more to add really. Moreover, theres really no incentive to add anything, even if there is some error in Jacques analysis:
I can’t speak for anyone else, but I mean you peruse the paper rapidly and the first things that sticks out instantly ‘CM violation, fermions are wierd I dont understand what hes doing, the generation structure is weird I dont understand what hes doing, quantizing the theory will be hellish, etc’. And then you recall usual problems with traditional E8 models, like issues with chirality… One suspects that too will probably come back and probably bite him.
Point being it doesn’t really give much incentive to probe into the details of the group theory, given that the theory is in such a primitive early stage of research. Which is why you don’t see many people bothering to pull out their old group decomposition tables and verifying things explicitly. Seans original post is right on target imo. Physicists have a ton of papers that are required reading everyday, we simply don’t have time to go through the details of every one of them, so we make subjective judgements about our time management and put our faith in the peer review process as well as word of mouth.
Hi Prof. Smolin,
You do realize it is mainly thanks to you that this spectacle occurred, don’t you? If Jacques Distler felt obliged to get involved and try to clarify the situation when there were other things he would much rather be doing, and if his annoyance about this manifested itself in a more abrasive tone, that would be quite understandable I think.
“Does Lisi’s proposal survive Distler’s second post? Even if there is some truth to Distler’s argument…”
Can you clarify what you mean by “truth” here? Distler presented an explicit mathematical argument; are you suggesting that it might not be correct (i.e he made a mistake in it somewhere), or that it is somehow not relevant, or what? If it is the former, can you say where the mistake is, or which steps need clarification, or specify precisely what your objection is?
“A bunch of people who think they own the territory of unification are enraged. They react with all the classic symptoms of territory defense that the sociologists of science have catalogued…”
I think you are kidding yourself about that. At any rate, I count myself among the “enraged” in this instance, and it is not because I’m a string theorist (I’m not, and have no love for them) or because unification is my territory (it isn’t, and in fact I care very little about it). The real reason for the outrage (in my case, and many others as well I expect) is that it was totally irresponsible of you to hype this supposed “theory of everything” to the New Scientist journalist (which set off this spectacle) without being correct in your judgement that it merited the hype. It is embarrassing, if not downright harmful, to the physics community.
“So what is really happening here? What has happened is that one very smart, but intellectually isolated young theoretical physicists has made a bold and risky proposal for unification of physics…”
That reminds me so much of the aggrandizement of “brilliant” young string theorists that I’ve heard so often in the past. So I will just repeat what I always say to that: If so-and-so is really so great, let him go prove it by publishing some papers in PRL. If plodders like yours truly, who were judged undeserving of support by pretty much everyone they ever applied to (including you), were able publish there repeatedly then it should a piece of cake for these really smart folks.
Seeing as Lisi’s work is “fabulous”, why don’t you encourage him to submit a short version of it to PRL?
It seems that your vision of how the physics community should be involves a complete rejection of the traditional procedures for assessing the importance of peoples work. Assessments should not be based on such outdated things like getting published in the top journals; being a “seer” addressing the “big questions” is all that matters. Being bold and risky, writing papers with over-the-top titles and claims of tremendous results, modulo a few small details to be sorted out later, these are the folks we should respect and admire now. Those boring types with limited imaginations, plodding away on their piddling little problems, thinking that it signifies anything when their incremental technical advances get published in PRL – ha! they can all sod off and go to hell. Let’s get rid of them and replace them all with people who have the courage and boldness to be working directly on the big issues for unlocking the secrets of the universe!
It is no secret that I am not a big fan of string theory, for several reasons: 1) I spent the first 20 years of my career, such as it now was, on the receiving end of unchallenged string theory propaganda, 2) ST appears to disagree with experiments and 3) I have my own crackpot ideas about quantum gravity. However, as Victor Kac once said to me, it is more important to be correct than to be politically correct. In this case it seems to me that Distler’s analysis is just correct.
Hi Moshe (#212): Jacques, a few years ago, when CV started out, we had a nice discussion of what can be done using this medium, following Clifford’s post I believe. I thought at the time […]
Any chance you could dig out a link? I’d be interested to have a look.
—
While I am here, and while some people are around that have invested time thinking about the matter, I’d just like to repeat a question I’ve asked in several other places. Regardless of whether the theory is chiral or not, can incorporate all generations or not, I don’t understand how the dynamics can work out (naturally, without fixing by hand). If one treats the fermions like the gauge fields, writes down an action with unbroken symmetry, and then break it, I can’t see how the fermionic part for the Lagrangian can come out with the correct order of derivatives?
Sorry if that’s a stupid question – the reasoning is just if you start treating fermions like gauge fields, then how come they can eventually couple differently? Having fields that transform under the right Lorentz representation isn’t sufficient, there is no DpsiDpsi term in the SM Lagrangian, there is just one D too much. Lisi fixes this in his paper by picking a Lagrange multiplier that in the fermionic case is just psi without derivatives. Anybody has a thought on that? Is this a constraint that can come out naturally? I’d be interested to hear.
Best,
B.
As far as I can tell, there seems to be a consensus among the CV commenters that:
1. We think denigrating and insulting people is a legitimate part of a scientific discussion.
2. We think doing this anonymously is fine too.
3. We don’t understand why it is so hard to have serious discussions about physics on blogs. We suspect it is because PW keeps interfering with them.
Have I got that right?
Sean, I know you’ve been known to write that you don’t read the comment section of your own blog, but keep in mind that you are legally and morally responsible for what appears here. The decision to provide a forum for anonymous attacks by some of your colleagues (and I have good reason to believe that H-I-G-G-S is someone that you know) on another one is yours to make, but I think it’s a misguided one. Until the appearance of blog comment sections, there was no legitimate medium with wide distribution where people could anonymously attack their colleagues. No one who controlled a public information source that was widely read would allow this to go on. Unfortunately one of the main innovations of this new technology is to provide an outlet for disgraceful, unprofessional behavior that no one previously would tolerate.