Friday, June 28, 2013

Strings 2013

Guest blog by Daniel Grumiller of ITP Vienna, a participant

Lubos asked me if I would write a short summary of Strings 2013, and since I appreciate the cohomology of his blog [all blog entries, modding out the non-physical state(ment)s] I decided to oblige.

If you are interested in the actual content of the talks I suggest you listen to them (or view the slides) here.

If you want an excellent and witty summary please watch Jeff Harvey's summary talk or view his slides. I cannot do a better job than Jeff, though I will add a few, mostly irrelevant, personal comments at the bottom of this text.

The outlook by the "higher authority" can be found here. The final conclusion by David Gross is that string theory is alive and kicking, with which I agree.

Here are a couple of miscellaneous comments, which I just add to convey an epsilon of the excitement that accompanied this conference, despite of the absence of "revolutions".
  • Strings 2013 was extremely well-organized. While the same remark applies to some previous Strings like in Munich last year, this time everything went so smoothly that you hardly noticed the stress that inevitably comes with the organization of such an event. Much like good electrical wiring in a house, you notice that it is done perfectly through not noticing it at all, except that all the lights work.
  • Seoul is an excellent venue. It is my first time here, and I enjoy very much the city, the culture, the excellent subway, the food, the hospitality and the alphabet.
  • The talks were brilliant. Let me not rank them, except that from a purely aesthetic perspective Greg Moore's talk certainly won the first prize. Just look at p.2 of his talk. From a technical perspective, I was impressed by all the talks of the "younger generation" (see next item).
  • Jeff Harvey provided a \(\ZZ_2\) classification of the audience into PhD before/after 1999 and gave two separate sets of three questions. If you have not done the quiz on p.9 of his slides you could do it now. Belonging to the young generation, I was tempted to give the answer "four" to his first question, but he was only counting down from three (ok, actually my answer to part of his tricritical question differs surely from what Jeff would have counted as the correct answer; I would have said that \(c=7/10\) is special since, together with \(c=1/2\), the corresponding CFT is dual to Einstein gravity in 3 dimensions)
  • Given that I work on related issues it was great for me to see again the presence of higher spin gravity (Igor Klebanov's and Matthias Gaberdiel's talks, as well as David Gross' comment on his third big question). But I also enjoyed the variety of excellent review talks and selected technical talks. Inevitably, in some of the talks I felt a bit like in Jeff Harvey's (or Gary Larson's) cartoon on p.7 of his talk.
  • The gong show was again interesting. If you do not know this format: every speaker has at most 5 minutes, after which the screen goes dark and the micro is switched off. There were 13 speakers. If this sounds stressful for speakers, organizers, audience and the chairman you get the right idea. It is still a good item at such a type of conference and impressive how much (useful) info some people can convey in this short time. The last gong-speaker, Michael Gary, gave an excellent summary of our \(W_N^{(2)}\) gravity paper.
  • The banquet was phantastic, both from a culinary and a performance view point. I also enjoyed Neil Lambert's humor in his dinner speech, though I am not sure all his remarks were appreciated. He mentioned that he did not follow Jeff Harvey's 1998 Macarena/Maldacena performance with a "Gaiotto style" performance since Davide was absent, a remark which earned applause of relief. To compensate, the organizers displayed this video after the last talk today, while people were leaving the auditorium (I guess the non-younger generation left more quickly at that point).
  • Strings 2014 will be in Princeton.
In conclusion, Strings 2013 was an excellent conference in every respect, in particular from a scientific perspective.

The text below by LM was posted on 6/27.

Seoul, Korea is the place where the music for Newton's Pendulum Gangnam Style was born.

Xmphysics released the video above just 3 weeks ago. The most successful rendition of this song-plus-dance has attracted over 1.6 billion views on YouTube. Seoul is also the place where the string theory annual conference takes place.
Strings 2013: talks, titles, PDF, videos
The videos from the talk are being posted via YouTube: you should click at the blue video icon and then the Quicktime-like icon on the next page. Incidentally, I like the 1-second jingle at the beginning of the YouTube videos and I think it's sensible for conferences to post their videos via YouTube instead of various do-it-yourself video frameworks.

Those of us who are following what's going on aren't surprised by most of the topics that the speakers – famous and well-known enough string theorists – have been thinking about recently.

One of the 30-minute talks I am going to watch – I am watching it now, in fact – is Shamit Kachru's talk about the Mathieu Moonshine which I already mentioned in when it was discovered. The monstrous moonshine has been discussed on this blog many times; in string theory, the Monster group has been linked to a Leech-lattice-based compactification of string theory as well as the pure AdS3 gravity.

But the Mathieu group is one of the smaller sporadic groups among those 26 or 27 ones and the moonshine links it to some calculable properties of K3 compactifications of string theory. Shamit's talk is nice but he says some wrong things, too. For example, moonshine isn't called moonshine just because it is "enigmatic" but because Andrew Ogg promised a bottle of Jack Daniel's whiskey (moonshine) in his paper to the person who explains a moonshine-based relationship.

Otherwise, John Schwarz has already given an introduction you may watch. Nima Arkani-Hamed about their new way to calculate the gauge theory amplitudes. Shiraz Minwalla and Dan Jafferis chose topics related to Chern-Simons theory. Rob Myers, Juan Maldacena, and Tadashi Takayanagi talk about entanglement's links to holography and spacetime topology while Joe Polchinski tries to update the so far seemingly invalid AMPS discussion of the firewalls in particular and the black hole interior in general. He clearly tries to react to Maldacena-Susskind and I will study his talk in more detail later.

You can read all the titles and topics yourself, many of them are interesting.

I've watched Kachru's, Maldacena's, and Polchinski's talk. There were lots of interesting things in them but Joe's talk is just plain wrong. He believes to have a newer version of the AMPS argument – a direct proof that a generic black hole microstate must have every internal field-theoretical mode in an excited state, with the average occupation number well above zero (around 10:00 in the talk). This is, of course, bullshit. Even if you consider a relatively young black hole, much younger than the Page time, it's easy to see that the more empty the black hole is, the higher entropy it has. As it is initially losing some energy by the quasinormal/ringing modes, its entropy is still increasing. Once these ringing modes are emitted, the entropy nearly stabilizes – it gets maximized – and of course that the corresponding value of the internal field theory field modes' occupation numbers converges to zero in this regime. I am talking about field modes expressed in a freely falling frame. Of course that some accelerated observers will see Unruh's radiation whose modes' average occupation number is nonzero but this is not new and it doesn't contradict anything about complementarity. Polchinski concludes that CFT in AdS/CFT is an incomplete theory of the bulk. Holy cow. If AdS/CFT says something about the quantum gravity in the bulk, it's true and it's the whole story.

BTW Michael Gary (thanks, Daniel!) cleverly asked Joe what prevented the firewalls from destroying any place because it's the Rindler horizon. Joe answered that the states of the Rindler horizon that don't have the firewall are non-generic – generic states have it, too. That may be a cute way out but we may still consider the numerous states that don't have the Rindler horizon. Their entropy may still be high, within this set, there's no firewall, and this set may still be analogous to all the black hole microstates in the black hole case. Andy Strominger said that there should also be other ways to see the firewalls if they existed. Joe interrupted Andy before Andy asked the question but the question was finally asked, anyway. Joe tried to answer the question by mixing firewalls with fuzzballs. Just to be sure, Sumir Mathur of fuzzballs considers Joe's firewalls wrong. Andy asked why the firewalls were a quantum gravity issue – as it is claim to invalidate arbitrarily large black holes in GR. Joe answered that he believed the nonlocality in QG to be arbitrarily brutal. This is clearly a doomed attitude because classical GR is one of the defining features of the general concept of QG and if we can't isolate any subset of regimes in which classical GR applies, then the notion of QG is clearly insufficiently constrained to be well-defined. Daniel Harlow made similar comments etc.

I will probably watch some talk about a solid discipline to improve my tastes, e.g. Xi Yin's talk...


  1. Mr. Motl what do you think about this video regarding test of String theory with photons simulation ?

  2. After the first minute, I thought that I didn't have to see the remaining 2 or 3.

  3. It looks like the strings2103 website has gone offline because they did not buy enough bandwidth. Do you know what the youtube channel is called?

  4. Watch it all please, because of point is at the end. There is also another video regarding 3d fractal, that I developed and called REthreeDiG. I am developing special effects for animations. Accidentialy I found interesting effect with one 3d object sphere that has only reflections one pattern " Cardioid". I 3d modeled this " Cardioid" and reflections were only one pattern " Mobius Strip". Interesting thing is that shadows and reflections (Mobius Strip patterns) match with String theory, but to prove it I need to make better quality animation with more patterns Mobius Strip. Also interesting is connection and disconection of Mobius Strip. According this two facts I think, there is thing you could have a look on it ;) There is also other presentation regarding 3d fractal REthreeding, have a look if you would it is regarding progress how I reach to this postulate, but sorry about colors with effects that I developed I am making paintings 8)

  5. Hi , Lubos . This is a somewhat strange question . Is it possible to do string research and publish it (On say ArXiv) without being affliated with a physics department or even having an undergrad degree in physics ? That's I'll not be endorsed . If my research is good enough and publishable will I be able to join graduate school after that ? (They'll not take missing formalities like Bachelor too seriously ?)

  6. John F. HultquistJun 27, 2013, 5:04:00 PM

    When I visited trf this morning, the internet, in its infinite
    wisdom, has plastered two large ads with “stand with president obama + support climate action” - - one across the top and the second just under the photo of the most famous person from Pilsen. The US President’s photo is several sizes larger than yours. That seems unfair.

    After clicking through to the day’s full post those ads went
    away (HP laptop gets the top spot) and the League of Conservation Voters ad came as an animated square in the text, apparently with audio.

  7. alejandro riveroJun 27, 2013, 5:05:00 PM

    It is funny to try to read the talks from the ASR feature of youtube:

  8. Dear Phil, I placed you on a whitelist.

    One of the videos was linked to,

    so you may see that the name of the channel is Strings Sogang. However, the videos are classified as non-public in some way so while you may see them, they don't appear in any searches and not even in the list of videos posted by this user.

  9. LOL, it starts serious but it eventually switches to gems like:

    the quotes a crime charged today is associate about global you one cemetery

  10. Dear nabill, the need for endorsement is one of the changes of the arXiv in relatively recent years. You may still post on the "physics" arXiv without an endorsement, I guess.

    If you can't get endorsement from the experts who are otherwise likely to be in the target audience, it probably means that the readers of the same arXiv - similar folks - wouldn't enjoy your paper, either. It's not a rock-solid rule but it's very likely.

    If you discovered something stunningly important (and right) and placed it in the world, perhaps despite experts who should have known it was valuable but they didn't, and so on, you could be accepted to a grad school, get a Nobel prize, or whatever. The probability of something like that, given the facts I know about your situation, is something like 0.0001%.

    More likely, if you can't get even an endorsement for your paper, it probably means that it is totally insufficient to get you to a grad school and even avoid rather rudimentary requirements such as a Bc-like degree. I've been on admission committees many times and I can guarantee that you couldn't get to Harvard under such circumstances even if the paper actually started to get dozens of citations etc. which I find unlikely by itself, too.

  11. alejandro riveroJun 27, 2013, 5:16:00 PM

    ASR is a big telepathy tool :-D He does not hear the voice but the inner thinking of the speakers. I strongly suggest to enable them while seeing the video.

    Aside, if you want to link full transcripts of other videos, you see the mechanism of the tool, simply change the /id/xxxxx tag in the url. I took two days to program it, only to discover now that there is an option in youtube itself (transcript) allowing to see them!

  12. I'm asking here because I contacted two persons at harvard , One said that It's certainly possible given my background knowledge(Self-learning) , GRE score and research experience to join grad school even without bachelor's degree. The other person said that it's impossible to join grad school without bachelor's degree .

  13. But aren't undergraduate students supposed to know just the elementary concepts like elementary electrodynamics , mechanics and QM ? Knowing something like QFT and conformal field theory to the point of being able to do publishable research using them even if it's not paradigm-shift or stunningly important should be a bonus , right ?

  14. See the last page of Douglas presentation

  15. Dear nabill, I am not able to find an explicit statement in the regulations for the Harvard Graduate School, Physics

    that a Bc degree is needed but it's needed in most other schools of the Harvard Graduate School of Arts and Sciences I checked - see the first sentence of prerequisites at

    for example. But even if the Bc-or-more degree weren't really required, I can't imagine that someone without it could realistically get to the school unless he or she were really famous and promoted by several members of the committee etc.

    Believe me, I served twice or thrice on the committee. There are about 400+ candidates a year - for the physics PhD program. Less than 30 is typically accepted. Each of the 400+ folders seems to be crowded with certificates and grades and recommendation letters and proofs that they did all the required exams and so on and so on. I think that a candidate with a missing portion of these basic things would get so bad grades that his or her chances would be de facto set to zero.

    To get there, one would have to get a powerful advocate who would be more than a rank-and-file professor and who would have to convince most of the admission committee that it's legitimate for the candidate to circumvent the standard selection by grades given to each folder.

    It's of course possible that someone without an undergraduate background will be equally good as or better than people who have gone through an undergraduate education. It's just that you haven't convinced me it's your case so far and most people who would claim such a thing - that they're better and may avoid the standard procedures - would almost surely be inadequate which is why it's sensible that such methods aren't being pursued.

    Let me tell you that I was probably as close to your circumvention as I could get but it was still very far from your case. I got to the Rutgers grad school and my pretty well-known papers at that time allowed my adviser Tom Banks to convince some officials that a deadline could be softened (extended by a week? I wasn't even told the details or I forgot them) and it's plausible that I have avoided some particular language exam condition, too (I would have passed the exam in Czechia if I wanted and needed but chances would be high that I would be failed if I were trying to go through such an exam in the U.S., especially because of the spoken part if there were any). That's it. I of course haven't circumvented any physics-based requirement linked to exams, degrees, or something like that, although I would also have doubts about the universal ability of these "formalities" to quantify someone's competence.

  16. Thank you very much , Lubos . It's seems like it's much harder than I thought .But , I hope my chances are not zero , I'm living in a third world country and they've built a new theoretical physics institution (The only one in the country) I think they might accept me as a grad student and I could be able to do my research ,get experience , and recommendation letters. Perhaps this will raise my chances to join harvard grad school .

  17. "such a berry has a finite feathers bpr
    super strength"

    I can imagine a science journalist nodding and taking notes for his "The LHC will destroy the universe" article.

  18. I look forward to this weekend to cautiously peek into some of these things :-)

  19. Lubos, was a little surprised to hear Maldacena say QM has "some spooky action at a distance, but no signalling".

  20. I would keep the status of this phrase as an "annoying verbal habit" that doesn't have to be assigned a truth value or a meaning, for that matter.

    Einstein introduced the phrase as a phrase exactly equivalent to a signalling - so nothing can be spooky action at a distance but not signalling because the two concepts are the same thing. Others who have adopted the phrase have redefined it in various vague ways etc.

    When folks clarify what they exactly mean, they always end up saying something wrong. For example, the most cited paper with the phrase in the title is

    140 cits. They say that that correlation is either explained by A influences B, B influences A, or A and B have common causes in common past. But they immediately say that entanglement is none of them. But it's complete bullshit. Entanglement squarely fits to A and B have common causes in the common past. The correlations may violate Bell's inequalities because it is *not* classical physics, stupid. But conceptually, the origin of the correlation - think about the singlet (Bell state) as the simplest entangled state - is exactly the same as it is in classical physics, as it is in Bertlmann's socks etc.

  21. Gross is whining that there were only few String phenomenology talks implying somehow that current research is not trying to address specific BSM questions and guide experimentalists.

    I don’t understand why. Each year there is a separate
    conference dedicated to String phenomenology. He must be aware of this of course.

  22. I personally find it unfortunate just like Gross does. There are string phenomenology conferences but there are similar not-the-largest conferences about non-phenomenological stringy topics, too. On the annual strings conference, each topic should be represented reasonably and I find it sort of insane that 1-2 talks (Cvetic and who is the second?) are dedicated to string phenomenology among 50.

  23. I personally find it unfortunate
    just like Gross does. There are string phenomenology conferences but
    there are similar not-the-largest conferences about non-phenomenological
    stringy topics, too. On the annual strings conference, each topic
    should be represented reasonably and I find it sort of insane that 1-2
    talks (Cvetic and who is the second?) are dedicated to string
    phenomenology among 50. In my optics, string phenomenology is something
    like 1/4 or 1/3 of the research. not 1/50.

    HCG recipes phase 2