An Exceptionally Simple Theory of Everything?

It’s been unusually long since my last posting, with the main reasons being that

  • Not much has been happening on the math/physics front…
  • I’ve been busy learning more about geometric Langlands, which is a daunting subject. I keep intending to write something about recent work by Witten and others in this area, but saying anything both correct and intelligible seems a rather challenging task that I haven’t been quite up for.
  • Garrett Lisi has a new paper on the arXiv, with the rather over-the-top title of An Exceptionally Simple Theory of Everything. Sabine Hossenfelder has a typically excellent posting about the paper, and Garrett has been discussing his work with people in the comment section there. Lubos Motl, has a typically, how shall I say, Lubosian posting on the topic.

    I’m the first person thanked in the acknowledgment section of the paper, but at Sabine’s blog Garrett explains that this is just because he is using reverse alphabetical order. I’ve corresponded with him in the past about his research in this area, without being able to provide any real help other than a certain amount of encouragement. Two of the ideas he is pursuing are general ones I’m also very fond of. One is well-known, and many people have also tried this, it’s the idea of bringing together the internal gauge symmetry and the symmetry of local frame rotations. The problems with this are also well-known, and some have been brought up by the commenters at Sabine’s blog. I don’t think Garrett has found the answer to this, or that he claims to. I’m still hopeful that this line of thinking will lead somewhere, but think some dramatically different new idea about this is still needed. The other idea he likes is that of trying to interpret the fermionic degrees of freedom of the BRST method for handling gauge invariance as providing the fermions of the Standard Model. I suspect there is something to this, but to get anywhere with it, a much deeper understanding of BRST will be required. I’ve been spending a lot of time trying to understand some of the mathematics related to BRST in recent years, and am in the middle of writing some of this up. It seems to me that there is a lot that is not understood yet about this topic even in much simpler lower-dimensional contexts, so we’re a long way from being able to really see whether something can be done with this idea in a realistic four-dimensional setting.

    One idea Garrett is fond of that has generally left me cold is the idea of unification via a large simple Lie algebra like E8. While there may be some sort of ultimate truth to this, the problem is that, just as for GUTs and for superstring models, all you’re doing when you do this is changing the unification problem into the problem of what breaks the large symmetry. This change in the problem adds some new structure to it, but just doesn’t seem to help very much, with the bottom line being that you get few if any testable predictions out of it (one exception is with the simplest GUTs, where you do get a prediction, proton decay, which turns out to be wrong, falsifying the models).

    Anyway, I’m glad to see someone pursuing these ideas, even if they haven’t come up with solutions to the underlying problems. Garrett is a serious and competent researcher who has pursued a non-traditional career path, and was recently awarded a grant to by the FQXI organization. You can read more about him in an article on their web-site.

    Unfortunately, some of the reaction to Garrett’s article has been depressing. A commenter who sounds well-informed but hides behind anonymity goes on about “this nonsense” (although Garrett’s polite reaction to him/her did lead to a more sensible discussion). Early on in my experience with blogs I believed that no serious professional in particle physics would attack someone and try and carry on a scientific argument anonymously, so any such comments had to be coming from misguided students, or someone not in the profession. Unfortunately I’ve all too often seen evidence that I was wrong about this. Lubos Motl on his blog denounced the fact that Garrett’s paper appeared in the hep-th section of the arXiv, then later wrote in to Sabine’s blog to crow that it had been removed from hep-th. As always with the arXiv, how moderation occurs there is non-transparent, so I don’t know how or why this happened. My own experience with the arXiv over trackbacks to hep-th has been a highly disturbing one. The current hep-th policy seems to be to allow any sort of nonsense to be posted there if it fits into the current string-theory-based ideology (see for example here), while suppressing any criticism of this. A paranoid person might be tempted to wonder whether hep-th is being moderated by someone so ideological and petty that criticism of string theory or including string theory critics in an acknowledgment section would be cause for having ones article removed from hep-th…

    Update: I hear from Garrett that the story of this paper at the arXiv is that it was submitted to gr-qc, not hep-th. Before it was posted, it was re-classified as hep-th, and appeared there. Later on (after the appearance of Lubos’s blog entry denouncing the arXiv for allowing the paper on hep-th I believe), it was re-classified again, this time as general physics (with cross-listing to hep-th).

    Update: Latest news about this is that the paper has now been reclassified again, to the perfectly appropriate hep-th, cross-listed as gr-qc, although no one seems to know why this happened. Another continuing mystery is the trackback situation: there are four trackbacks to the paper, to postings by Lubos, Bee, and to Physics Forums, as well as to an old TWF from John Baez that doesn’t even link to the paper. My postings still seem to be non-trackback worthy on hep-th, not that I can argue with this particular case, since the discussion elsewhere has been more substantive (except for Lubos’s, which is valuable for the way it accurately represents the hysterical reaction to speculation that is not string theory speculation all too common in certain quarters).

    Update: Garrett is making the news here. Whether this is a good thing is yet another question for debate on the next thread, I guess. A lot of the attraction for the media seems to be his personal story. Maybe it’s a good thing for physics for people to see that one can be a theoretical physicist while surfing in Hawaii…

    Update: Lisi-mania spreads. See stories in New Scientist, the Ottawa Citizen, Slashdot, and probably lots of other places I haven’t noticed.

    Update: Steinn Sigurdsson has an excellent posting summarizing the situation. As usual, blogs are the place to get the highest quality information about scientific issues…

    Update: I’ve given up on keeping track of the media stories on this. For some discussion of the representation theory involved, see this posting by Jacques Distler, and comments from Garrett.

    Update: The Angry Physicist examines the Distler critique in some detail.

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    176 Responses to An Exceptionally Simple Theory of Everything?

    1. DB says:

      In the comments section to Lubos Motl’s blog entry on Lisi’s paper:

      http://motls.blogspot.com/2007/11/theory-of-everything-triples-traffic.html

      he reveals the apparent cause of his departure from Harvard as follows:

      “The obvious and inevitable result is that those people with IQ below 100 not only control most of the general public but start to include ever increasing groups of people.

      This physics-related pressure was at least as important for me to leave those circles as the purely political issues about the academic freedom because I became pretty much certain that all these things would be getting worse as time goes.

      When I was first suggested by relatively powerful people that I should have been treating complete idiots such as Peter Woit as my peers if not more, it was just way too much for me. We may be ready that the society may misevaluate many things, nothing is perfect, but these things are just many orders of magnitude out of proportion.

      What about next, I would be thinking. Would cranks with their ‘theories of everything’ who know less than 1% what I do and whose IQ is 45 below mine – literally an inferior species – would be placed upon us or even dictate what we can think about physics? Well, this epoch just here. It has become politically incorrect to say that what surfers like Garrett Lisi are doing are light years away from what theoretical physics is. The closer one is to the top of the real physics, the most impossible it is for him or her to declare any opinions. With a realistic idea about psychology and social science, where do you think that the society will be going if the relative influences are arranged in this way?”

      Speaks for itself, doesn’t it?

    2. wolfgang says:

      Garrett,

      it seems that a central idea of your paper is the claim that BRST ghosts can become real fermions due to the special properties of E8 and your action. But you do not really explain this ‘trick’ in your paper (and you do not discuss quantization really).
      Do you explain this somewhere else or do you have plans to elaborate on this point in a follow-up paper?

    3. Peter Woit says:

      Brian,

      To understand the paper, at a minimum you need a graduate level education in particle physics, including a good understanding of the theory of Lie algebras.

      On the whole, I think the hullabaloo in the press and on the internet isn’t a good thing. There’s a huge amount of nonsense being spread, of different sorts:

      1. The press stories aren’t awful, with reporters mostly trying to include some skeptical comments about how speculative this is, while at the same time as much as possible making an enthusiastic story about the latest “theory of everything”. Unfortunately, for reasons I explain in the latest posting here, I think these kinds of stories don’t really do much in terms of explaining what is really going on to people, often giving a misleading impression.

      2. Comments on Slashdot and the blogs are all too much dominated by the huge number of people who think it is a good idea to write in about things they don’t understand, happily spreading misinformation or irrelevancy, and burying serious comments under a mountain of junk. The noise to signal ratio on Slashdot is so high that very few people who actually know something about this subject are willing to waste their time reading the comments or trying to contribute to the discussion. Too many comments on this blog and on others come from people who don’t actually know much about the topic at hand, but feel compelled to share whatever is on their mind anyway.

      3. Some blogs and commenters try and fit this into the ongoing string theory/LQG warfare, which it isn’t especially relevant to. As usual Lubos can be counted on to obscure whatever sensible criticism he might have with crazed rants about how people who aren’t string theorists are lower life forms.

      Blogs do sometimes manage to provide a place for some sensible discussion, even amidst a heavy helping of nonsense. In this case, the best I’ve seen is Sabine’s blog, which has provided a forum for Garrett to discuss some of the issues raised by his paper in detail with her and others.

    4. Aaron Bergman says:

      As best I can tell, he uses the term BRST a few times, but there is no real BRST procedure in the paper. It’s only used as a term to justify the formal addition of grassman and commuting variables in his “connection”. But, of course, the BRST symmetry is a Grassman symmetry, not a commuting symmetry like E_{8+8}, so (like many other things in the paper) it doesn’t really make sense to me.

    5. Peter Woit says:

      DB,

      Still unclear to me whether Lubos jumped or was pushed from Harvard. But it is clear that one part of the story was his being driven over the edge by the fact that criticism of string theory has been taken much more seriously in recent years, both by the public and by the physics community.

    6. Mark Paris says:

      I agree with Garrett that this is a very exciting time. Congratulations to him on getting some very interesting and compeling work out. It’s encouraging me to take a break from dynamical coulped-channel approach to meson production reactions to have another look at some issues of GR that I’ve thought about in the past.

      Curiously, the question of renormalization doesn’t appear to be getting too much play here. It seems that while the E8 unification proposed could solve some issues of organization, the fundamental issues of spacetime properties and particle properties still remain distinct. Garrett’s bet that LQG will solve this issue is probably not all that much of a sucker’s bet. It seems like background independence will be a key concept in the resolution — to me anyway.

      But that’s only “half” the problem. There seem to be two issues regarding renormalization. The non-renormalizability of GR has already been mentioned. But also, loop integrations will apparently still lead to divergences in the E8 unification — the theory enjoys no supersymmetry cancellations, for example. Then we’re stuck with infinite renormalizations — fine, we’re used to it. And physics can still be done. But the precision required to fix the couplings will make, I fear, accurate detailed predictions impossible. Spectroscopy make still be possible however.

      Background independence seems to offer a way out of this aesthetically unpleasing situation.

    7. Aaron Bergman says:

      the question of renormalization doesn’t appear to be getting too much play here.

      Well, yes, because the theory has any number of barriers to being quantized. And even before that, the theory breaks the symmetry explicitly by the Lagrangian, so it’s tough to say that things are really being unified here.

      As for couplings, there are none as best I can tell. So, it’s very unclear how one recovers the standard model from his structure.

    8. Michael Crowley says:

      Hi Peter,

      Just wanted to let you know there is a very long and passionate discussion of this gentleman’s theory on my favorite website, Democratic Underground. Naturally, we are not scientists, but I’m happily surprised by the passion aroused by this post. Just thought you might find it interesting.

      http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=389×2281653

      Hope that link works; I’m not sure how to post links here.

      Take care, and thanks again for your marvelous book.

      Mike

    9. Michael Crowley says:

      P.S.

      I’m obviously “Mike03”, making a fool of myself as usual and also referring people to your blog.

    10. Bee says:

      Regarding the pun: It might be perfectly obvious to everybody who works in theoretical physics, but I doubt many people of the broader public or even the journalists got it. Was it explained anywhere than here? I am constantly making terrible puns like this, which is always source of a broad confusion. But besides this, it’s somewhat unfair to blame things on the title, there are other examples (testing quantum gravity! testing string theory!) that go the same way. It’s probably a consequence of of people’s sensitivity to news become lower and lower, because there’s such an over flow of unbalanced hypes that needs to be filtered (not only in science). It’s a very bad trend though. I mean, I do appreciate attention for theoretical physics, but things like this make the news, nothing comes out of it for the next some years, no revolution, no incredible insight, no change in world view etc, and people will start to wonder ‘what ever happened to’, do these theoretical physicists just make vacuous announcements that never come down to anything? All the while support dwindles for the less spectacular basics.

      Let me give you an example. My husband is working for a scientific publisher in Germany. They publish a book series that contains literally every stupid fact about material sciences you need, and there’s still data that’s added since people are working in the field. It’s an extremely boring read, it gets sold maybe to some thousand libraries worldwide for an horrendous price, since it takes a lot of time and effort editing. Nevertheless, it’s an essential for anybody working in the field. Now it looks like the publisher will stop the series because it just doesn’t pay off. I’ve suggested they apply for governmental, but not sure if they will do (its a rather large publisher having plenty of better fields to focus on). What I am trying to say is that not all we do is hip and cool and we’re not all surfer dudes making E8 animations. Events like this raise in me the concern that support might go increasingly into media-suitable research.

      Hi Garrett:

      “Wow, apparently I’m an imaginary construct dreamed up by Lee Smolin!”

      I neither said that, nor meant to say that. I am just as always surprised how much such stories about the alleged outsider (surfer dude! no university affiliation!) attract cheerful attention, whereas the ‘inside of the ivory tower’ is accused of ignorance and arrogance.

      Hi Eric:

      ” Hi Sabine, Actually your place in the Smoliniverse is as the young, beautiful woman who happens to be a brilliant and creative physicist. It’s very sly of Lee to choose you as part of his public relations campaign.”

      I know you didn’t mean it to be insulting, but it is. I’m neither Lee’s nor anybodies PR agent.

      Best,

      B.

    11. Bee says:

      “I’ve suggested they apply for governmental,”

      should be

      “I’ve suggested they apply for governmental support,”

    12. TE says:

      I would like to see the action expanded explicitly in component fields in a notation that particle physicists can understand.

      Then, by inspection we should be able to check that:

      1) All fields propagate with the correct signs in their kinetic terms
      2) Higher derivative couplings are absent or suppressed by the Planck scale
      3) All fields have the correct spin-statistics relation

      or other obvious signs of inconsistency.

      So far it is not clear to me that this theory is even consistent at low energies. I have not spent the any time decoding the notation to see if the above consistency constraints are satisfied. But I shouldn’t have to… these issues are absolutely crucial and should be addressed prominently and explicitly in the paper.

      Only after these basic hurdles are mounted, we can begin to discuss whether the model is useful or addresses any important problems.

    13. Garrett says:

      TE:
      The action is written down in an efficient expression on page 25. I did use some fancy math tools, including Clifford algebra and the Hodge star, instead of using indices. However, over the following two pages I expanded the terms of this action in detail, including writing out the resulting Dirac action in curved spacetime, in indexed components. I did this because I share your desire for a complete and understandable exposition, in conventional notation.

      You should be able to glance at the expanded, local coordinate form of these expressions and confirm they match those of the Standard Model, with all the correct signs, factors of 1/2, no higher derivative couplings, and the correct spin statistics. It is true that the original action was chosen by hand such that this comes out, but given the efficient expression used, I consider it non-trivial that this works.

    14. Eric says:

      Sabine,
      I’m sorry that you found that insulting, but I was just making a joke and trying to complement you at the same time. The basic point is that if Smolin did want to use someone for PR, you would be a good choice. In any case, let’s face it, this whole media thing with Lisi’s paper is completely unwarranted. There’s really no content there, just some big statements and nice pictures. It’s really amazing that this work was funded by the Foundational Questions Institute, unless you consider that Smolin is on the scientific advisory panel. Even Smolin I’m sure knows that this work is wrong, but I believe he has an ulterior motive in supporting it.

    15. Bee says:

      Hi Eric,

      I was just making a joke and trying to complement you at the same time.

      Apology accepted.

      if Smolin did want to use someone for PR, you would be a good choice

      Definitely not. I’m a researcher, Eric. The attention my blog currently gets is about the maximum I am comfortable with. I am not writing it because I want to advertise PI, Lee’s book or my papers, but because I like writing it. Since I am currently not teaching I find it a nice way to contribute my part to spreading knowledge, and to share the fascination my job brings – still, and still in new ways.

      In any case, let’s face it, this whole media thing with Lisi’s paper is completely unwarranted. There’s really no content there, just some big statements and nice pictures.

      The paper has content, and I’ve explained in my post in great detail which. What it does not provide in my opinion is a Theory of Everything, so I agree that the media hype is unwarranted.

      It’s really amazing that this work was funded by the Foundational Questions Institute, unless you consider that Smolin is on the scientific advisory panel. Even Smolin I’m sure knows that this work is wrong, but I believe he has an ulterior motive in supporting it.

      I don’t want to comment on Lee’s opinions, but it is quite astonishing to me how you can be ‘sure’ about what he thinks. Best,

      B.

    16. Marcus says:

      When you see a new theory in formation it’s legit to guess that the gaps will be filled, new things found to reconcile it with observation, and the theory will complete itself (if it looks to you like it will) and it’s likewise kosher to guess that the gaps and imperfections won’t be worked out and the theory won’t complete.

      Then if it is completed and firm predictions are derived it’s anybody’s guess whether experiments confirm or refute. Whether its right or wrong is a later issue. With the E8 theory we are seeing the outlines of something emerge and it seems to have both some problems and some nice features.

      What’s not acceptable is to hammer the theory relentlessly as if to punish it for the fact that it attracted general public interest. Whatever the public does or does not do, when you crit some new theory development it should be constructive—when you point out problems you should acknowledge how they might be resolved, at least in the first weeks and months when the whole thing, the only thing that matters, is whether or not the theory gets other researchers interested in working on it.

      People in the public don’t have to be protected from believing something might work. Plenty of them are smart and skeptical enough to know that proposed ideas often don’t work, and they like to hear about new ideas anyway. It’s common sense that new ideas can interbreed and morph and help start other ideas—that some will disappear forever and others you will hear about a few years down the road when they re-surface. I think the public knows that, or a substantial sector does.

      In Garrett’s case, what I read that he said sounded calm and forthright enough. He was constantly pointing to parts of the theory that he was dissatisfied with and looked to improve. And he was repeatedly pointing out that it could turn out wrong—and might not agree with experiment.
      I heard pride, but I did not hear hype.

      The public reaction I saw was interest, but not whole-hog credulity. I don’t think it was contrary to the longterm interests of science. Just normal reaction to some good news. It’s good news that this new idea is out there trying to take shape, whether it’s eventually shown right or wrong. And I really doubt anyone can confidently say at this point.

    17. Peter Woit says:

      Eric,

      I’ll delete any more comments insulting people, I don’t want my blog used for this. You might want to note that this tactic hasn’t worked for Lubos, I suspect one reason Garrett’s paper got so much attention was that people read what Lubos had to say on the topic, and drew the conclusion that there must be something to it.

    18. Arun says:

      I’m now veering to the opinion that science should be created in privacy, like babies.

    19. King Ray says:

      Garrett,

      I’ve only scanned through your paper briefly, but I can already say that your theory is 10^500 times better than string theory!

      Does your theory shed any light on why the electro-weak group is U(2) and the electro-strong group is U(3), and the overall group is S(U(3)xU(2))? I’ve always wondered why the U(3) and U(2) determinants were related in that way, i.e., epsilon_abc*epsilon_AB is an invariant (lower case indices are electrostrong 1-3 indices, upper case are electroweak 1-2 indices). This has to do with the global structure of the gauge group of the standard model. If you assume that the global group is S(U(3)xU(2)), and that anomalies cancel in each family, then you get a unique solution for the hypercharges in a family (given the SU(3) and SU(2) reps of the quarks and leptons):

      http://prola.aps.org/abstract/PRD/v43/i8/p2709_1

      In your theory it is probably just due to the E8 structure. Have you looked at any possible anomalies and their cancellations?

      Keep up the good work. I agree with Lee Smolin, it seems to be the most promising TOE for a while if everything works out. I never liked the plethora of gauge bosons that came with large gauge group GUTs.

      BTW, I have surfed at Pt. Mugu. Very powerful waves there.

    20. Garrett says:

      (My last comment was to Arun)

    21. Garrett says:

      King Ray:

      Almost all GUT’s explain S(U(3)xU(2)) the same way, and this one is no different.

      I haven’t investigated anomalies yet, no.

    22. King Ray says:

      Garrett,

      I can understand how larger gauge groups explain the global structure, for instance in SU(5) the U(3) and U(2) are block diagonal in the 5×5 SU(5) matrix and the total determinant must be 1, implying S(U(3)xU(2)) after breaking the SU(5), but can you elaborate a little on how it works in your theory? You don’t have many extra gauge bosons like SU(5) or SO(16), do you?

    23. Garrett says:

      King Ray:

      That’s what the paper’s for.

    24. King Ray says:

      Garrett, ok, thanks, and BTW I meant SO(10) not SO(16)! Brain cramp or senior moment…

    25. Kralizec says:

      Sabine Hossenfelder (Bee) said:

      I am just as always surprised how much such stories about the alleged outsider (surfer dude! no university affiliation!) attract cheerful attention, whereas the ‘inside of the ivory tower’ is accused of ignorance and arrogance.

      The familiar sort of story you mention seems to be a product of the recurring antagonism between “the many” and “the few,” or “the people” and “the great.” Aristotle’s Politics and Machiavelli’s Discourses on Livy are both helpful regarding the properties and interactions of these recurring factions. Popular writers seem to have cast Garrett Lisi in the role of a man of the people who is challenging the great and proving again that the people are their equals in every way (including theoretical physics). I think Machiavelli discusses examples in which one of the great suspects that a man of the people is being supported covertly by another of the great. He appears to teach that the antagonism between people and great is reproduced among factions of the great.

      In case you decide to read the works I named, I’ll just make mention that Carnes Lord and Joe Sachs are good translators of Aristotle and that the best available translation of Machiavelli’s Discourses is probably Harvey Mansfield’s. Mansfield is also highly regarded in some circles as an interpreter of both Aristotle and Machiavelli.

    26. mitchell porter says:

      In the discussion at Sabine’s, Garrett seems confident that “quantum E8 theory” is at least mathematically well-defined and therefore must be exploiting some loophole in Coleman-Mandula, even if he doesn’t know what that loophole is. Whereas Aaron Bergman is very skeptical but asks whether he’s missing something in the construction.

      Surely this issue can be resolved. I am climbing a steep learning curve in order to participate here, but I have a few thoughts.

      Let’s start with the classical theory. Garrett has an E8-valued connection on 3+1 dimensions. He has an action (his equation 3.7) which explicitly breaks part of the E8 symmetry, including the part which notionally mixes fermions and bosons. I say “notionally” because those terms don’t mean anything until we quantize.

      Now compare this situation to the Standard Model coupled to gravity. A classical theory exists here too; then you get to the quantum theory by substituting operators for fields in the usual way.

      This seems to be the crux of the debate with Aaron. You don’t need a super-Lie algebra to quantize the Standard Model, because the fermions and bosons don’t have to mix. Is it the same for Garrett’s theory? If the action didn’t already contain those symmetry-breaking terms, wouldn’t Aaron be right? But given that it does, does that mean that Garrett’s right? Section 3.2.3 must be the key here, because that’s where the “fermionic” action is extracted.

    27. ScienceLover says:

      Popular writers seem to have cast Garrett Lisi in the role of a man of the people who is challenging the great and proving again that the people are their equals in every way (including theoretical physics).

      It hasn’t gone that far right now. Lisi has not become a research politics factor – the common man challenging the establishment. Instead the media phenomenon shows all characteristics of a 15-minutes-of-fame story.

    28. Dany says:

      King Ray: “This has to do with the global structure of the gauge group of the standard model. If you assume that the global group is S(U(3)xU(2)), and that anomalies cancel in each family, then you get a unique solution for the hypercharges in a family (given the SU(3) and SU(2) reps of the quarks and leptons)”.

      Hi King Ray,

      In case that you missed it, see also arXiv:hep-th/9801011v1

      Regards, Dany.

    29. Arun says:

      Sorry for being disjointed here – why I’m thinking now that science should be developed in private, outside public gaze is that we’ve protested string hype – the public claims made by physicists that a theory will deliver what it cannot (yet?). We ought to be protesting Lisi E8 hype as well for exactly the same reason. No double standards in this matter, please.

    30. King Ray says:

      Dany, thanks, I have seen that reference as well as Saller’s papers. The paper I cited above is referenced in Agricola’s article that you cite and Saller’s book (Vol. II) and papers. Was there a particular point in Agricola’s paper that you were referring to?

    31. Marcus says:

      we’ve protested string hype – the public claims made by physicists that a theory will deliver what it cannot (yet?). We ought to be protesting…

      Arun,
      impartiality and consistency are indeed essential but so is a sense of proportion.

    32. Garrett says:

      The hype is dying down. I’ve tried to make it very clear to every reporter I’ve talked with that no matter how beautiful and promising a theory looks, its validity is determined by predictions, and how those fare under experiment. And that with any new theory, including this one which is still developing, an attitude of healthy skepticism is appropriate.

      The thing worrying me is… this E8 Theory was playing out very well in academia before the media hype. I gave four talks on it, in quick succession, and each one went better than the last, with a very good reception from physicists. And the paper generated a great deal of interest. Then what I thought would be a nice explanation for a lay audience in New Scientist spawned a media frenzy. I just hope the hype didn’t obliterate serious consideration of the paper.

    33. King Ray says:

      Garrett,

      I believe that you have handled yourself and the publicity as well as possible.

      Last night I read all the posts on Bee’s blog, and I think you handled all the attacks and criticisms that came your way in a manner that showed a great deal of class and dignity, always answering every question or challenge in a good natured way.

      In everything I have read that you have said, I have detected no trace of your trying to overhype your work, as string theorists have been very guilty of doing with string theory. All I detect is the natural excitement and enthusiasm of a theoretical physicist for his work in trying to understand the laws of nature.

      In every instance you are extremely honest and straightforward and always point out that the theory is in its early stages and could prove to be wrong, and that it will make predictions that will be testable. I find this quite refreshing and admirable. My hat is off to you for the way you have conducted yourself.

      It might be useful for you to write a more expanded version of your paper, that is more in the notation familiar to particle physicists, where you carefully and redundantly explain your steps and methods, as if you were teaching a week or two long class on your theory. A review section on the key points of Lie algebras and group theory relevant to your work might also be useful, to bridge the gap, since the theory of exceptional groups may be an impediment to many. It is always good to show simple examples and then talk about the general case. I know it is hard to try to do something like that when you are in the middle of doing important work, but it could help your cause tremendously.

      Keep up the good fight!

    34. Aaron Bergman says:

      A review section on the key points of Lie algebras and group theory relevant to your work might also be useful, to bridge the gap, since the theory of exceptional groups may be an impediment to many

      This is not the problem. Everyone knows about E_8, Clifford algebras and BRST symmetries — they’re standard material. What makes the paper difficult to read (for me, at least) is the lack of standard notation (all the tildes, underlines and dots, for example), and a number of missing steps in various derivations. I would like to see a detailed step-by-step derivation of the standard model using standard notation. I’d like to see the exact subgroup of E8 we’re using and the decomposition of the adjoint rep of E8 under that subgroup with each rep labelled with respect to every factor in the subgroup.

      The standard model has a well-known set of fields with a well-known set of quantum numbers and interactions. The paper presents a rather piecemeal approach of getting to the standard model stuff, and it didn’t make much sense to me. I’d like to see the Lagrangian (3.7) expanded out in its full glory, so to speak.

      Basically, right now it feels to me like reading the paper is a chore, and I have better things to do. It’s not even clear to me at the moment what the resulting symmetries of the Lagrangian are, and the more things I have to figure out when I read the paper, the less urge I have to do so. Sounds selfish I know, but such things are true about papers in general — you should try to make things as easy as possible for your colleagues.

    35. Arun says:

      Sounds selfish I know, but such things are true about papers in general — you should try to make things as easy as possible for your colleagues.

      A good reminder that to have one’s ideas taken seriously by the scientific community is a hard-earned privilege, not a right.

    36. woit says:

      Arun,

      I think there is a significant difference between the overhyping of Garrett’s work and the overhyping of string theory. One has to do with a very speculative idea that just one person is working on, the other a very speculative research program that has dominated particle theory for a couple decades, involving thousands of people. I don’t think we’re anywhere near yet the situation where some of the smartest graduate students in the subject are leaving the field because they feel that only if they work on Garett’s theory could they find an advisor and start a career for themselves at the best graduate programs.

      There’s a constant stream of overhyped articles in the press about specific speculative ideas in physics being promoted by one person or a small group. New Scientist has such an article almost every week. Commenting on all such articles would take a lot of time, and get them more attention than they deserve, so mostly I think it’s best to just ignore them

      The media Lisi-mania is a much more unusual phenomenon. It has gotten a much wider distribution than usual, so it’s a good idea for physicists to put out some more realistic points of view. I think the blogs on the whole have done a good job of this. Anyone who reads the coverage here, at Sabine’s blog, and at Sean Caroll’s should get a pretty accurate view of what is going on. They could also read Lubos’s blog, but he is likely to just convince them that Garrett has definitely accomplished something revolutionary that has driven string theorists insane.

    37. Dany says:

      King Ray:” I have seen that reference as well as Saller’s papers. The paper I cited above is referenced in Agricola’s article that you cite and Saller’s book (Vol. II) and papers. Was there a particular point in Agricola’s paper that you were referring to?”

      King Ray,

      I mentioned I.Agricola since you referred to 1991 paper by J.Hucks. My guess was that you know all of them, but just in case… I think the discussion of his results is off topic here. In addition, I consider it not adequate to the blog with the general title “Not even wrong”.

      Regards, Dany.

    38. King Ray says:

      Dany, no problem, I appreciate your pointing out the paper in any case, so thanks again.

    39. Arun says:

      Peter,

      The current hype sounds to me like Pons-Fleischman cold fusion, or more charitably, Taleyerkhan’s acoustic cavitation bubble fusion.

      -Arun

    40. woit says:

      Arun,

      I think we’re still quite a ways away from the Pons-Fleischman level of media frenzy. And that was an experimental claim, which led to many groups doing experiments to try and replicate the results (as well as physicists selling platinum short, convinced that the way platinum had been bid up because it was the catalyst Pons-Fleischman used would soon collapse as the results weren’t replicated). Claims from serious experimental physicists saying they have an inexhaustible source of free energy are rather more rare than claims from theorists that they have made progress towards a ToE.

    41. Kralizec says:

      ScienceLover Says:
      November 17th, 2007 at 11:45 pm

      It hasn’t gone that far right now. Lisi has not become a research politics factor – the common man challenging the establishment. Instead the media phenomenon shows all characteristics of a 15-minutes-of-fame story.

      Thanks; I understand, ScienceLover. I’m not, myself, suggesting that Mr. Lisi fits into a people/great frame of the sort I described. It just appears that some popular writers (and perhaps at least one fellow physicist) are trying to understand the physicists and Mr. Lisi in terms of that continually re-emergent sort of antagonism.

    42. Pingback: The Blog of Lon » Blog Archive » See God, Kai: A New Theory of Everything

    43. amused says:

      The description of what has and hasn’t been done in this paper should be made a lot clearer. E.g., I, and quite a few others it seems, got the impression that this was supposed to be a unified field theory with E8 gauge symmetry containing gravity and the SM. The e8 gauge connection and its curvature are discussed at length in a way that gives the impression that they are to be used to construct the action for the fields, presumably an e8 gauge-invariant one — otherwise, why go on about it? If this had really been the case then there would be an immediate issue with the Coleman-Mandula theorem. The remark in the paper about C-M not being relevant because the spacetime is deSitter is nonsense, since Poincare symmetry can be assumed for all practical purposes when applying the theory to particle scatterings in labs.

      The real reason why C-M turns out not to be relevant here (as noted by Aaron B. over on Bee’s blog) is that the action proposed for the fields is not e8 gauge invariant: Despite the impression the other parts of the paper give, the actual construction of the action is not based on the e8 connection and its curvature. Instead, it is pulled together from various parts of the e8 curvature in a way that breaks the e8 gauge symmetry; the action is not invariant under transformations that mix the gravitational and internal gauge parts of the e8 connection. This seems really ad hoc to me — there is no governing principle like gauge invariance for determining the action, it is just cooked up to reproduce the gravity and the SM. (This seems to be Bee’s objection as well, if I understood her comments rightly.) In light of this I don’t see any compelling reason for expecting that the new “color scalar fields” that arise have anything to do with nature. So at this point it seems that the paper is just one more not particularly well-motived proposal for what beyond the SM physics might look like. (String phenomenologists already have loads of these, apparently.) Well, it is not even that yet — first one would have to quantized the theory, determine the particle content, renormalizability etc. But a unified theory it certainly isn’t — where is the unification?

      As for the media hype, “surfer dude stuns physics” makes for a cool story but it wouldn’t have happened without the backing of some big-name physicist. Smolin was most obliging in this role, but I’m sure it was for the purest of motives (let’s not be getting cynical here ;)). I share very much Bee’s concern about episodes like this leading to an atmosphere where people feel pressured to be working on media-appealing, hypeable topics rather than solid, conservative ones.

    44. Bee says:

      Hi amused:

      This seems to be Bee’s objection as well, if I understood her comments rightly.

      You did. Best,

      B.

    45. Harry says:

      Mr. Lisi is now making the headlines in France, in one of the most famous newspaper :

      http://www.lemonde.fr/web/article/0,1-0@2-3244,36-979858@51-979860,0.html

      (in french)

    46. H-I-G-G-S says:

      One does not have to examine the full E_8 structure to see the
      “non-unification” unification aspects of the construction. Consider his
      “unification” of the quarks and gluons of QCD using G_2. It is true that the 14-dimensional adjoint rep of G_2 decomposes as the 8 + 3 + \bar 3 of SU(3) under G_2 -> SU(3). And it is true that the gluons are in the 8 and the quarks and anti-quarks in the 3 + \bar 3. So what? What action does Dr. Lisi propose? I am very sure that if you wade through the obscure notation one will discover that either

      1) It is the same action as that of QCD in which case G_2 plays absolutely no role in the contruction.

      2) It is not the same action as that of QCD in which case the theory is ruled out by experiment.

      It is a lazy author that can’t be bothered to work out the simple consequences of his theory and explain them simply. And it is a lazy blogger (who is supposed to be an expert in representation theory after all) who blogs about a paper and adds to the hype without putting in a modest amount of effort to understand what is going on.

    47. Garrett says:

      amused:

      This is a great improvement. It appears you are now understanding (if not actually liking) the paper, as your factual statements are mostly correct. Now please consider that matching the standard model fields and dynamics to parts of the E8 connection and its curvature, with only a handful of exotic fields, is non-trivial.

      (You have passed through the first, second, and are now to the third stage of acceptance (described on Bee’s blog).)

      H-I-G-G-S:

      I chose (1). And I’ve tried to make the paper as succinct as possible. On your last comment, I’ll let Peter speak for himself.

    48. woit says:

      H-I-G-G-S,

      This posting in no way purports to contain a technical examination of the paper and its problems. I have put a “modest amount” of effort into understanding what is going on, enough to see several problems with what Garrett is trying to do. The sort of general unification/non-unification problem you bring up is specifically addressed in the posting. I don’t think there’s anything at all in what I wrote that hypes the paper, quite the contrary. The links I provided to places where it is hyped were given in the context of noting that I don’t think this kind of thing is a good idea at all.

      I’ll provide you with another link, to the discussion and my comments at Sabine’s blog, about how unprofessional it is to attack people from behind the cover of anonymity, evading any responsibility for one’s actions:

      http://backreaction.blogspot.com/2007/11/anonymity.html

    49. Hi Garrett,

      Sorry to wade in late to this thread…but as an outsider, I haven’t yet learned to talk shop with the physics media circus at full tilt. You guys should get that thing fixed…

      In helping us to understand the motivation for your beliefs, can you be at all specific about how you see the origins of E8 as a symmetry group? Is it effectively a black box to you or do you see a preferred set of objects (constructed without benefit of E8) on which E8 acts as natural symmetries? For example, do you have any insight into the Freudenthal/Tits magic square construction that is not already present?

      As you are likely aware, many of us hold the prejudice that if nature uses exceptional algebra as you assert, a complete physical theory based on E8 should eventualy illuminate its ‘purpose’ through some kind of principle of emergent exceptional symmetry. As best as I can tell, at this stage your paper treats E8 as an unmotivated combinatorial anomaly from mathematics to be used by physics.

      Lastly, there is a tremendous ammount of rich folk wisdom held by very respectable mathematicians about E8, most of which is unfortunately unpublished (as it is generally treated as a private hobby). If you would like to talk off line, I could recommend some folks to you who do not seem to be on your acknolwedgement list. This is pretty specialized theory even for Lie Group specialists.

      Regards,

      Eric

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