Sunday, November 18, 2007

After Math: The Lisi-Peak

The graph below shows the visitor statistic for Backreaction during the last month

The usual traffic to this site is almost periodic over the week. The minimum is Saturdays, with around 600, a peak on Mondays around 1000, a lower second peak on Wednesdays, and then the next weekend drop. If we have a longer, well elaborated post with subsequent discussion this shows up as deviation from the standard curve with a one day delay.

Unfortunately, I can't show you the annual traffic, because our first SiteMeter died in April for reasons I still don't understand. The overall trend however seems to be subject to many search engine details that lead people here who are actually looking for something different. In this respect it seems to matter that this blog runs at blogspot, and shows up very prominently for all kinds of keywords, e.g. "first day of fall". We had a fun period last year when we were the first hit on Google image for "Map of America". Either way, this is just a background noise that pushes the statistics. Occasionally it seems, one or the other accidental visitor browses the archives, but most I am afraid are just annoyed by Google's inefficiency.

On the other hand, I found that the blogger 'search' field is completely useless and I search this blog more efficiently by entering a keyword into Google together with the tag 'Backreaction'.

To come back to the curve above. If you look closely, you'll see a first deviation from the usual periodic on Tuesday, Nov 6th, which I think is a delayed response to my post on the Casimir Effect. The post about Garrett's paper went out Tuesday evening, so caused the higher Wednesday peak on Nov. 7th. The unusual peak on Nov. 9th is the link from Peter Woit's blog, which increased the average traffic through the following days. On Nov. 14th the Telegraph article went out. The NewScientist article was subscription only until Nov. 16th. The following peak was caused by a multitude of links, among others from digg/reddit, various other well frequented blogs, traffic through Google searches for "Garrett Lisi", and a lot of links from around the science blogosphere (most show up on the very bottom of the comment section, in case you are interested.)

I hope one or the other random visitor got hooked :-)


  1. Hi Bee,

    you hooked me! And indeed Garrett's paper caused me to visit your site for the first time. I'm sure I'll return here often. Thank you for the interesting blog.

    To be sure, I rediscovered my love for theoretical physics after reading Lee Smolin's book. But Garrett's paper reinforced this.

  2. Hi Guido:

    Welcome :-) Lee writes very nicely, doesn't he? I'm working on a post on the Cosmological Constant that I hope to have finished some time next week (I've promised to write it already a year ago or so...). Best,


  3. Hi Bee,

    thanks for the welcome :). Indeed, I liked Smolin's book a great deal. I've been bugging my colleagues about elementary particle physics the entire week because of it. One of them pointed me to Garrett's paper, asking me what it meant. I tried to tell him about Yang-Mills theory, the importance of Lie groups, GUTs and TOEs but I'm not sure he understands. Do you also find it hard to explain modern physics to the layman? I think it's a pity that almost no-one understands it.

    I can hardly wait for your post on the cosmological constant. Back in the day when I studied Astrophysics (1990 something) it used to be zero, and this was a problem. Now it's non-zero and it seems it still a problem.

  4. Do you also find it hard to explain modern physics to the layman? I think it's a pity that almost no-one understands it.

    Well, it requires some thought but with good will on both sides, it usually works out somehow. Besides people who are a priori convinced "all of physics is wrong" and they know "a completely new way to do it!" (these exist, just believe me), the biggest problem I encounter is that many people seem to have an aversion for maths that I don't understand, and which makes things unnecessarily complicated. In most cases, it wouldn't be hard to translate roughly a concept into symbols and then explain what the equations mean. Just that the standard reaction I get is 'I never understood maths at school'. I.e. many people are so convinced they can't understand it that they don't even try (or maybe it's just uncool, nerd factor and everything). I keep telling them, one can learn how to 'read' maths much like a language. 'Speaking' it is a different issue, and the actually complicated one.

    I think the problem is that the communication of modern physics to the broader public has been severely neglected during the last decades. It is getting much better now, thanks to books like Brian Greene's, Lisa Randall's, and Lee Smolin's. It will take some while though until people feel familiar with the concepts. Lisa e.g. had a very nice explanation of Feynman diagrams if I recall that correctly. If I read the politics or economy section of a standard newspaper, I think many people don't understand the details. But they are just so used to reading about taxes or the stock market, that they aren't afraid of reading it, as they might be if I'd give you Einstein's field equations.



  5. I hope one or the other random visitor got hooked

    I did :) Very interesting blog, which I expect I'll read regularly, though high energy physics was never my field. I haven't read Smolin's or Woit's book but, by the time I reached grad school, it certainly seemed that the field was reaching a dead-end -- so I picked condensed matter, and eventually ended up in computational biology. I really hope there is something to Garrett's work. It will be marvellous to see some testable new insights (and quite amusing if 30 years of work on string theory turned out to be wasted.)

  6. Hi Rahul:

    A welcome to you too :-) We're not really a high energy physics blog. My husband writes a lot about the history of sciences, and if I look at the posts we've had over the last year, a substantial amount is about astrophysics, cosmology, nuclear physics, general science, with the occasional book review. The hep factor comes from me reading the hep-th/hep-ph/gr-qc arxives in the morning, and I occasionally point towards one or the other paper.



  7. Hi Bee,

    - A totally unrelated post -

    When you need inspiration for your physics, there is a book called "Free Play" by Nachmanovitch that's a great read. It has no math.



  8. Hello Bee. I've been watching your blog for a while. It is pleasing that you consider unconventional ideas like Garrett's. Our generation will overcome "The Trouble" to make truly original discoveries. You will be on the links page soon.

  9. Bee

    Could you tell us about your mathematical developement. Were you mathematically precocious as a child? Were you involved in mathematics competitins? Did you do millions of integrals? Did you know anyone who was a math dummy and then suddenly blossom?

    I am of the opinion that people who can solve the canonical textbook problems,with high probablity, have extensive experience solving math puzzles and participation in math competitions at an ealier stage in their mathematical development.

  10. I guess that means that it's time to start stirring the pot some more. So what are you going to do next?

    The E8 java applet I wrote caused a big new record in visits over on my physics websites yesterday, but things are starting to calm down now. It got so bad that when I updated the code, the servers kept giving me stale copies from cache for 10 minutes.

  11. Hi Louise:

    It is pleasing that you consider unconventional ideas like Garrett's.

    Well, I actually don't find Garrett's idea particularly unconventional. It is very puzzling to me that it creates such an upheaval. He builds upon only well known stuff that people have tried for GUT models for a long time, he knows his Lie-algebras, Dynkin Diagrams, and mixes it with some other less known differential form tricks from the LQG side, details of which elude me since I've never actually worked with it. It seems to me, he has put pieces together that were previously available - in a certain sense, that's what all the great breakthroughs have been. Nevertheless, as I have pointed out in my post, I remain sceptic because he has made a lot of leaps of faith, that I am not sure yet can be put on solid feet.

    Hi Anonymous,

    I'd find it really odd to talk about my childhood with an anonymous commenter on my blog.

    Hi Carl,

    If you think I'm too naive to realize you are just using my comment section to repeatedly leave links to your site, you're mistaken. Please don't abuse my hospitality.



  12. Garrett is a damn good surfer. He has been called a crackpot, but he's no kook.

    The traditional paths in the sciences have been overwhelmed by the sheer numbers of scientists that have been trained in the last 25 years. In the earth sciences, my specialty, we have suffered from too little funding and too few jobs for too many scientists for many years now.

    Garrett did the smart thing, living out his dream to surf big waves and searching out his own path in physics. Even if his TOE comes up short, he has lived well.

    Thanks for the excellent blog. It provides for open peer discussion, which has many advantages over behind-closed-doors peer review. Here the reviewers comments are peer reviewed. Transparency in the review process is much needed.

  13. I'm sorry you see things that way Bee, please delete my post. Yes, I've been programming a lot the last two days and wanted to share the results. Garrett sent me his color assignments and I will implement that next. But I'll try to avoid leaving links over here as I can see it is an issue.


  14. Hi Bee,
    I'm glad to hear you are writing about Lambda. I hope you will take a look at the paper Aldrovandi and Pereira posted yesterday where they calculate a value for it. At the moment I think I see a hole in their derivation, but can't be sure.

    I'm frequently finding myself in the awkward position of advocating consideration of stuff you seem to disapprove.

    It seems unmannerly to go against the wishes of such a hostess--I think the word is churlish. I would apologize except that isn't cool to apologize.

    Anyway, you will post on the cosmological constant and I will, if I hsve the courage, try to upyhold the view that even if Aldrovandi and Pereira's approach is flawed (!) at this point,
    it is still something to consider.

    Tracking mud on the carpet of the web's most charming and creative hostess, I remain your everlastingly humble and disobedient servant.


  15. Hi Carl,

    I'm presently not in the mood to clear this up, I'd have to rewrite my previous comment. Just try to avoid it in the future. I don't generally mind if you point towards related stuff, but the reason for this posting was definitely not that "it's time to start stirring the pot some more". Unfortunately, I can't look at the applet, it tells me to get a browser update.



  16. Hi Marcus,

    Thanks for the note. I didn't read the paper, and it will not be subject of my post. Best,


  17. Dear Bee,

    this reaction was really a surprise! As a side effect there are now quite a lot of spam "links to this post" distributed at random over the previous posts...

    But the next longer text of mine (still not ready, sorry) will probably bore away excitement-seeking new readers ;-)..

    Best, Stefan

  18. You hooked me! I added your blog to my feed, so keep the goods coming :-D

  19. I posted this over on another forum, but thought I might as well put it here too, since I went to the trouble of writing it out.

    I'd like to try to state part of my objection to Dr. Lisi's theory. There are many aspects of it I find incomprehensible, starting from the very first equation, but here I'll focus on the Coleman-Mandula theorem and the alleged loophole in it. This is actually an interesting topic for me for other reasons, so it's a little more fun to write about than the rest. I think there are also much more basic problems and I usually think it's better not to swat flies with sledgehammers, but OK.

    First of all, what is the Coleman-Mandula theorem? It states that if a theory has a symmetry group that contains the Poincare group then the group must have a direct product structure (the P. group times something else). (There is a loophole that allows supersymmetry, but since E_8 is bosonic it doesn't apply here, and furthermore there's another theorem that proves supersymmetry is the only such exception.)

    The P. group is the group of isometries of flat space. If you know a little about general relativity, you know that if there is any matter or energy of any form, space is curved. Such a lumpy space has in general no isometries at all, and certainly not the full P group. Of course we live in a space with stuff in it - just look around you - an expanding universe full of matter and energy, which is definitely not flat space. So why should we care about the C-M theorem if the space we live in isn't Poincare invariant?

    Furthermore the C-M theorem applies to a mathematical object called the S-matrix which almost certainly doesn't exist in any kind of cosmological spacetime. So naively it really seems irrelevant to the real world.

    However something should bother you at this point. In the standard model of particle physics we always do all our calculations assuming space is perfectly flat. Throwing caution to the winds we blithely compute S-matrix elements, and when we compare them to experimental data we find they agree to an accuracy unprecedented in the history of science (at least 10 significant figures for some quantities). How can that be, given that we are ignoring the curvature of spacetime and computing something that doesn't even exist in our world?

    The answer comes from the size of the effects of that curvature on particle physics experiments. They are of order (H/E)^2, where H is the Hubble scale of the universe (which in turn is related to its energy density) and E is the typical energy of the particles involved in the experiment. Now, how big is that? Generally, around 10^{-60}, give or take a few orders of magnitude. But our calculations (for other reasons having nothing to do with this) are accurate only to about 10^{-10}, so this effect is utterly negligible. And therefore even though Coleman-Mandula may not apply quite precisely, the mistake we are making in using it is far too small to care about.

    Let's come back to Dr. Lisi's theory of everything. According to him his theory produces the standard model plus gravity, but not in flat space - instead, in de Sitter (dS) space. We're asking whether his theory has a chance of describing the real world. What dS is exactly isn't relevant: it's a space with curvature, and let me simply tell you that if we are indeed in a dS space the curvature had better be smaller than, or of order of, the observed curvature in the universe today. Any larger and his theory would be ruled out by large-scale physics (cosmology, solar system tests, solar physics, etc.). Now how his theory (which has no parameters in it) manages to produce a solution with a characteristic curvature scale 30 orders of magnitude below that of the standard model (not even mentioning the 19 parameters of the standard model itself) is but one of the host of problems confronting it, but let's give him all that and proceed.

    So what's the problem? Well, it's that if Dr. Lisi were correct, he'd have a theory in a de Sitter space that's within a 10^{-60} error of a theory that violates the C-M theorem (because his theory certainly does not have a symmetry group that's a direct product of the gravity sector with the SM - indeed, that's the whole point of it from the beginning). Put another way, I could approximate his theory to an incredible degree of accuracy with something that we know by C-M is mathematically inconsistent. But if that were possible (it's not) C-M wouldn't mean a thing, because you could always evade it by adding an infinitesimal energy to your theory. Not only that, but all of the constraints and consequences of Poincare invariance (which include some of those 10-digit predictions) would be in the trash.

    So that is an abstract - but very general - reason to be extremely skeptical of the existence of this theory.

  20. Hi Sol Invictus,

    If anybody had cared to read my post on Garrett's paper, you'd have noticed that I pointed out there that the value of the CC in his model is problematic

    "When it comes to the cosmological constant, it seems for his theory to work he needs it to be the size of about the Higgs vev, i.e. roughly 12 orders of magnitude too large. (And this is not the common problem with the too large quantum corrections, but actually the constant appearing in the Lagrangian.)"

    and if you scroll down the comment section you will also find what he said about it.

    Everybody else: would you please restrain from announcing that you finally have realized the key points of that earlier posting. If I hear the word E8 one more time, I'll start screaming. Best,


  21. I did see that, actually, and would have posted in that comment section if I could figure out how. However my post here wasn't focussed on the obvious cosmological constant problem (which is at least as severe here as always). After all, he could always bite the bullet and just add a constant to the action to fine-tune it away.

    Instead I was trying to explain why putting the theory in de Sitter space does NOT constitute a loophole in the Coleman-Mandula theorem, which to me would have been the most interesting part of this. I apologize if that was redundant with something in the other comment section.

  22. Hi Sol,

    would have posted in that comment section if I could figure out how

    Had you at least read the last comment to that earlier thread you'd have noticed that I closed the comment section because it began to become redundant. Thanks for your explanations, as I mentioned earlier we might have a follow up post some time the next weeks, with a brief summary of the exchange, where those who are still interested can continue the discussion.



  23. hi bee,

    honestly, i don't buy the reason you give for closing that comment section. anyway, it was a nice reminder to me, that this is not a forum and you indeed are god here as often stated.

    thanks and bye,


  24. The indirect links, jumps across signature url etc, are getting a lower and wider peak but still noticeable. My own numbers (in, not a blog but a homepaga) were a modest 24 visits the Thursday, then 32, 27 and 22. To be compared against and average of 10 visits/day. A post in Cosmic Variance thread on Lisi brought 8 visits; the rest of the visits coming mostly from physicsforums, jumps from that page peaked at 26 visits the Friday (to be compared with and average of 5 or 6).

  25. Chris:

    a) I have stated exactly once that I am god as far as the comments on this blog are concerned, and I sincerely hope it remains sufficient.

    b) If anybody was subscribed to the comments on the thread to Garrett's paper he or she would have noticed I didn't actually delete a single comment.

    c) Please enlighten me, what might have been the actual reason for me to close that comment section that my subconsciousness might be hiding from me?

    - B.

  26. > If I hear the word E8 one more
    > time, I'll start screaming. Best, Bee

    Eee Ate is pining for the fjords!

  27. "I hope one or the other random visitor got hooked :-)"

    Here's another one. Love your stuff. Welcome to my (very short) blogroll ;-)

  28. Eee Ate? That is the new computer thing from Asus, isn't it?

  29. B8 two apples today, keeps the doctor away. Generally, I think we should pay more attention to vitamins, minerals and coenzyms in grand unified theories.

  30. Got hooked, Bee...
    Thank you, I went back to my studies and I'm enjoying fresh air...
    Wonderful blog and moreover "no strings attached" ;)

  31. Hello Bee;

    Great blog! I came in on the E8 wave but I'm here to stay. As my understanding is at a tourist level I'll keep my mouth shut. Keep up the good work.

  32. Hi Bee,

    In case you'd like to make a comparison, here is my (modest) traffic statistics. Nov 10 was when I posted a brief note on Garrett's paper.


  33. Hi Bee -

    I too, am hooked. I was googling "string theory" months ago, which lead me to you. I've enjoyed most of your writing, and always enjoy your good nature and your sense of humor.

  34. Did I get hooked? Well, probably not too tightly (my interests in theoretical physics are very sporadic in nature), but please count me in anyhow: There's an air af coming home in finding a physics blog that looks, feels and reads this Apollonic – as friendly, communicative, clear-headed & cleverly level as this one of yours.

  35. Hi All,

    Thanks for the many kind words :-) I hope I'll live up to your expectations.

    - B.

  36. gvzHave to add: the fact (no dispute!) that theor. phys. is not the only thing of interest in this blog may well get me...

  37. Not hooked, but certainly a repeat visitor now thanks to Garretts post. Unfortunately, my physics stopped after an undergrad course, so mostly I'm going to hope that your blog will start the rusty wheels turning again :)

    Good to know the internet is about more than just girls, gambling and flamewars!

  38. as Chris says, bye and thanks. but no thanks from me, i'll stick to Steinn S's blogspace for Lisi responses and info. much better all around......

  39. RE: "I search this blog more efficiently by entering a keyword into Google together with the tag 'Backreaction'. -Bee

    That works, sort of, but it's usually much more efficient to use "" before the keyword. Better by orders of magnitude in many or most cases.

    Yes, I landed in your blog space recently after an "E8 surfer dude" search.

    But I doubt that I am in the school of fish that you want hooked ... since my last formal dealings with quantum physics was when physics was my college major some decades ago.

    Although, I am a science addict by nature, so I've "fav'd" the blog and will seek to silently mine it for insights ... including the archives.

    William /wam

  40. I was browsing my RSS feeds today and I found something that must be useful for Garret. I might help that possibly "wrong" problem of SM generations.

    There seems strong evidences of violations of unitarity of SKM matrix up to 3sigma deviations. The first signs appeared aproximately on 2001. Now, the data accumulate at babar , aprox. 1 half billion meson B decays, will be analyzed for aproximately 2 years.

    A Particle of a Different Flavor?
    A simulated tauanti-tau event in the BaBar detector. (Image courtesy of Swagato Banerjee.)

    "A simulated tau/anti-tau event in the BaBar detector."

    Just as chocolate ice cream never spontaneously becomes strawberry or vanilla, leptons—electrons, muons and taus—are supposed to conserve their "flavor," or family.

    And there is a site that lists articles related to this issue.

    I think these ones are pretty interesting. Closely associated to the above news article.
    Check out other articles, if possible, but I thought this one is more clear.

  41. I forgot this one:

  42. Sorry, it is sigma 3 of not happening.


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