Friday, August 17, 2012

String theory is underestimated even by the enthusiasts

Matt Strassler has written a rant attacking the core of the state-of-the-art theoretical physics as well as the Milner Prize and its inaugural winners:
From String Theory to the Large Hadron Collider
He claims that the Milner Prize has generated a "controversy". What is it exactly supposed to mean?

Has someone presented some good reasons why great theoretical physicists shouldn't be getting awards? Or has someone summarized reasons to think that the inaugural winners aren't among the world's top theoretical physicists? If it's neither, what the controversy is about?

It's preposterous and Strassler knows it. There isn't any controversy here, just an indefensible and irrational screaming attempting to diminish the prestige of the greatest academic award in the world. The right word isn't controversy but jealousy.

He continues with this statement:
[String] theory’s been spectacularly over-hyped...
But this is a silly laymen's misconception. In reality, the richness of string theory is underestimated even by the enthusiasts, as Edward Witten has pointed out.

In the following sentences, Matt Strassler implicitly tells us that the value of a theory is measured by how much it helps with with his own career. I would kindly and humbly like to point out that the career thirst of a random egotist physicist isn't what determines the validity and the value of physical theories. The repeated comments about "Prof" Matt Strassler's career only help to highlight his ethical inadequacy as a potential judge. And as long as we are talking about personally uninteresting and uncharismatic physicists, no one really cares about their careers, either.
[I]t is high time the ball [in the "string wars"] were grabbed by the referee and placed quietly in the middle of the field where it belongs.
Great. Who is the best referee? As long as one is doing science, the best referee is the evidence itself, i.e. the compatibility of the theories with the observations and with the principles extracted from older observations, the theories' inner cohesion, their universal importance and relevance for many questions and phenomena in Nature, their ability to unify concepts and produce lots of insightful "output" out of very little "input", their ability to teach us something that isn't wrong.

Even if we thought that the evidence can't speak for itself and it needs to be personalized (and a real scientist should never think it's the case: he should be able to "hear" the evidence speak for itself), the best referees would be completely different than what Matt Strassler proposes. The best "personalized" referees would be those who have been most successful in extending, accumulating, and cleaning the body of evidence that science (or its relevant discipline, in this case high-energy theoretical physics) possesses. In other words, the best physicists. Because Edward Witten is a significantly more achieved physicist than Matt Strassler, it is more reasonable to listen to Witten's observation that "string theory is underestimated even by the enthusiasts" than to Strassler's insane opinion that "it is over-hyped".

Finally, Strassler suggests that the money similar to the Milner money shouldn't go quite to the best physicists but to those who need more support etc. I obviously disagree with that.

If a prize is supposed to have an elite status and be more than "just another grant", it has to go to the best folks whether or not they have already been awarded, praised, or paid. I am a great fan of Freddy Cachazo and a dozen of other folks whom I could enumerate (but I would surely miss someone) and a great fan of their research, I consider them extraordinary smart and hard-working, but one still needs "at least some time" for Freddy to be in the same league as Witten, Sen, or some other inaugural Milner Prize winners. I am sure that e.g. Freddy has a significant chance to naturally get there and I don't think it's right to distribute the "world's top physicist" prizes before they're justifiable.

Once again, there is a big difference between a "top prize for theoretical physicists" and "grants". There's a lot of fair scientific work that is pretty important, that is valid, and that deserves to be funded and it gets various grants. But Milner didn't create another grant that is paid to some people who may need it; there are lots and lots of grants of this sort. By having found an edible amount of money in his wallet (a concentrated capital that dwarfs competitors for simple numerical reasons), he created something that is designed to be the most important prize for theoretical physicists in the world. If it's supposed to remain credible, it must be given to the top big shots rather than to those who may need it more.

The winners were awarded for top contributions roughly in the last 33 years. ;-) The list of winners also includes people who wouldn't be called "string theorists" but "string theorists" still represent a slight majority of the winners because string theory contributed a majority of the high-energy theoretical physics breakthroughs in the last 33 years. In the past, the most important breakthroughs would be unrelated to string theory (and even unrelated to quantum mechanics) because string theory (and quantum mechanics) was unknown. But once string theory got discovered and its role got clarified, it became clear that the cutting-edge conceptual progress in high-energy theoretical physics has to depend on it (much like it has been obliged to respect the laws of quantum mechanics since the mid 1920s) so the percentage of string-theory-related breakthroughs among the award-deserving new discoveries in theoretical high-energy physics is bound to increase. Such an increase of the fraction of research that depends on the newer theoretical frameworks is an inevitable symptom of physicists' increasingly accurate understanding of the laws of Nature. Physicists have always been looking for more refined frameworks extending (or specializing) the previous frameworks, eliminated the wrong ones, picked those that weren't wrong, and continued to work on and refine the "more special" and "more advanced" theories.

After all, Strassler's (co-authored) most important paper (so far), Klebanov-Strassler, is a string paper, too. Cascading gauge theories as the AdS/CFT dual of some array of branes. Deep stuff.

When we talk about the balls and referees, Yuri Milner has made the most significant step to actually "return the ball back to the referee". In 2012, the main referee was himself, a man who had been learning to become a cutting-edge physicist but he gained impartiality by leaving the field and he showed that he isn't completely incapable of thinking by earning a few billions of dollars, too. ;-) Starting from the 2013 Milner Prize, the referees are 9 of the world's (20?) best living theoretical physicists. I sincerely hope that people will be interested in the next laureates and that this new meritocratic perspective will undo lots of the damage that has been made by the populist, anti-meritocratic, "everyone is equal", "everyone should talk into everything", the "mediocre people should always control the ball", and "everyone should get what he needs" degenerative memes represented by many writers unfortunately including Matt Strassler.

String theory is the indispensable core of the state-of-the-art theoretical high-energy physics – the deepest perspective into the inner workings of the Universe we have and, quite likely, we will ever have – and that's also the reason why it's sensible for it to be connected with the world's largest academic award. A person who doesn't even understand this simple proposition is rather unlikely to produce new insights that would place him or her in the same league with the inaugural Milner Prize laureates. The era when the deepest new insights about the Universe could have been obtained without string theory had already ended several decades ago.

And that's the memo.


  1. I'm counting on the top theoretical physicists to carry us to the deepest layers of understanding. They've already carried us very far and the best I can do is provide my support so they can carry harder.

  2. I think that for Matt Strassler String Theory has become the Forbidden Fruit.

  3. Whoops, reading the title of this article made me feel uncomfortably caught since I first thought Matt Strassler is just trying to calm things down and deter the sourballs and trolls from being that agressive and destructive with this one ...

    The huge amount of subtrolls, that suddenly appeared over there to troll about the Fundamental Physics Price and string theory of course, almost swept me away :-(((. And Matt Strassler did not give them appropriate answers or defend himself against their attacks ...
    This suddenly made me so worried about fundamental physics, feeling sad, despaired and unhappy :-(.
    Maybe hanging around over there too much is no good for me :-/

    I just love fundamental physics and what Mr. Milner has done for it is so great; I'd like to thank him so very much (if he reads TRF?) :-) !. And this TRF article probably was what I needed to not drown in the evil flood that tried to sweep me away, thanks Lumo :-).

    The Maser article I'll have to read later since my opthalmogist has put some very nasty drops into my eyes ...
    This is a valid excuse for my typos today too ;-P

  4. I agree with Strassler and anyone else who ridicules the Milner "prize" - it's the dumbest fucking award in human history.

  5. Dear Dilaton, there exist places on the Internet which I have trained myself to largely overlook – impose an upper bound on the time spent per average line (it is about 0.1 seconds), being aware that reading them wouldn't lead to anything constructive. Matt Strassler's blog's comment section belongs to this category.

    Hope you can still see with your eyes!

  6. Do you also have a reason for this less-than-maximally-flattering judgement, or are you just learning to swear? ;-)

  7. Right. He must have imposed the ban upon himself at some point, for some mysterious reason, and he may be getting ill by the shortage of the forbidden vitamins.

  8. Yes I have a reason, there are hundreds, maybe thousands of poets and other quiet intellectuals in the world whose output is barely read/recognised and have a far superior contribution to humankind's well-being than the awardees of the Milner prize.

    Being superbly anal at manipulating the mathematics of a complicated "game" in all sorts of ways is not deserving of an award until it proves itself against the hard fucking wall of reality.

    Sorry, but swearing is required to emphasise how fucking stupid the current state of affairs is.

  9. There are seven billion people in the world but you surely don't know a name of any living poet whose contribution to the mankind could be at least remotely comparable to the contribution of a Milner Prize winner, do you? ;-)

  10. Even a child describing his/her first feeling of awe is superior to a fixated mechanical string theorist's mathematical doodlings.

    I won't list poets, novelists or essayists who I admire since it would distract from my message that modern theoretical physics is a big FAIL.

  11. No, you didn't list them because you know that any name you would list in this way would be entirely preposterous.

    Theoretical physics is the main component of the true culture of our epoch.

  12. Theoretical physics is the Ultimate when done right. Newton. Maxwell, Einstein, Heisenberg all stand tall above any poet, but today everyone is fumbling things.

  13. The trap here is that singers are not considered poets anymore. Neither script writters, nor theatrical authors.

  14. Dilaton, I hope your eyes won't let you down so early ! ;-)

  15. The moment I learned of the Milner Prize I had a feeling of elation that lasted for hours. Anyone who reacted negatively to the news is a screwed up sourball.

  16. I think the reaction has to do with string theory, not with the money. You say "the best referee is the evidence itself, i.e. the compatibility of the theories with the observation." I would add, the ability to make predictions and then run experiments to test those predictions. We're still waiting for string theorists to made concrete predictions that are then backed up by experimental observations. The Standard Model is looking pretty robust, and string theory seems to be retreating. I am just a layman, but I would welcome references to concrete predictions later backed up by experimental agreement. Do that, and these complaints would turn into complaints against the Nobel committee for not awarding string theorists the Prize quickly enough.

  17. Yep Gene,
    I almost feel the same :-).

    First I felt like jumping up and down shouting in the same way football fans do it when their team scores a goal :-D.
    Then I suspiciously glanced at my calender to reassure myself that it is not April 1st and some trolls are making fun of fundamental physics and peoply who like it ...
    After reading some more news articles about it (with comments turned off ...) I experienced a feeling of elation that lasted for days :-).

    Now, the Milner Prize still makes me smile when thinking about it, but at the same time, maybe because I've not yet fully recovered from too many head on collisions with evil trolls outside TRF, I'm anxious about the screwed up sourballs who troll about the FFP. I mean, can they effectively do something about it ... :-/ ?

  18. Dear Lew, your would-be conflict between the Standard Model and string theory is completely nonsensical.

    The Standard Model is a quantum field theory with a particular field content that has to be extracted from the experiments, much like the coupling constants and masses; in the same way, there are compactifications of string theory and the data equivalent to the particle content and parameters - which compactification - has to be extracted from the experiment.

    But when it comes to the predictions at the LHC, quantum field theory as a framework gives practically indistinguishable predictions from string theory as a framework. To make the predictions specific, one needs to deal with a particular quantum field theory (the Standard Model) which means one must determine the field content and the parameters; the is an analogous extra choice - the choice of the right compactification - in string theory that is needed to produce the equivalent predictions of string theory. There are compactifications of string theory that have the Standard Model field content at low energies, after SUSY breaking.

    So the LHC experiments confirm quantum field theory exactly in the same way as they confirm string theory. Your suggestion that the LHC helps one over the other is just a proof that you don't have the slightest clue what you're talking about.

    To directly distinguish whether quantum field theory or string theory is the right description, or something else, one would have to study much more extreme processes than those at the LHC. This can only be done on paper and the result is that string theory survives and quantum field theory doesn't because quantum field theory is internally inconsistent in the presence of gravity that inevitably "kicks in" near the Planck scale.

  19. Hey James,
    what the hell hit you ... ?!

    I remember you as quite a nice and resonable person; I mostly agreed with your earlier comments about various things including physics topics.

    So what in the world makes you now troll like this ...?

    Not cool :-(

  20. Thanks Shannon and Lumo :-)

    my eyes are some kind of damaged but it is quite ok now and hopfefully it will stay like this. 2004 I had severe problems with retinal detachements but fortunately a nice surgeon could help me and prevent the worst .... Today I just had a routine checkup in Rostock and everything is still ok :-)

    Concerning Matt Strassler I will really avoid the comment section. Sometimes he has nice discussions with colleagues therein and some nice Dudes can showp up too :-D ... But it has become too much with the trolls and I'll just read some physics articles or posts about the LHC if I feel like and stay away from the comments ...

  21. Chad Orzel in this post

    is saying that particle physics is getting all the popularity while condensed matter is not getting anything.

  22. Just for the laugh, do you know that in French String Theory is called "la Théorie des Cordes" which literally means "the ropes'theory"... This is because "string" in French has another meaning : G-string.

  23. ..which is used as a catapult obviously.

  24. Dear Lubos,
    let me start by saying that I was very happy when I learnt about the Milner prize - I've been expecting something like this to happen for a while. And I really don't understand all those people who are trying to teach Milner what to do with his money. The winners of the prize are essentially synonymous with "physics" for me, so I have no issues with this.

    But I think there is no real contradiction between the statements "string theory is underestimated even by the enthusiasts" and "string theory is over-hyped". Let me use an old analogy. Don't you think that if you try to teach people something deep, there'll be the few who (kind of) understand you (and probably underestimate you), and there'll be the crowd, going
    all the way between "Osanna" and "Crucify him" ?

    Don't you believe that popularization often borders profanization and stimulates crank condensation?
    There are lots of people trying to build perpetuum mobile (way more than ones trying to find an elementary proof of Fermat's theorem, luckily). Don't you believe that the hep society is way too fashion-driven? Or that most of the physicists (say, within a sigma from the average) are deep inside mainly philosophers and theologicians?
    That physicists have very strong crowd instincts (as compared to, say, mathematicians).

    I realize these are questions about sociology, hence probably unfair, but let's assume you're actually better than Sheldon at these things.

    I guess I am trying to say that questions of fashion/hype are related to politics (i.e., policy making and crowd-managment). The fact that the tide is turning has nothing to do with the actual science. I actually think it's for the better: it leads to a better signal/noise ratio, by setting a strong filter (on a weaker signal). I tend to think it's healthier to be under-funded by the government than to be over-funded.

  25. As a merely interested outsider the string theory meta debate has been interesting.

    As a passionate string theorist I'm sure you will disagree with me but even from other string theorists they say it doesn't seem to be able to make anything we can or possibly now or ever test.

    From what I read understand it gives the most rigorous mathematical theory of all the forces / particles (but which ones is the issue)

    It seems we are in a backlash against string theorists. I have read before that you could only get a professorship if you were one. Now the tide is turning. Again, it seems from blogs and the popular science web. We might be in an era where things arent going to be learnt in decades but longer. Which would be terrible for short lived people like us.

    Ah, I finally found Feynmans quote, so Ill replace my crap with his gold

    ""People say to me, 'Are you looking for the
    ultimate laws of physics?' No, I'm not. I'm just looking to find out
    more about the world, and if it turns out there is a simple ultimate law
    that explains everything, so be it. That would be very nice to
    discover. If it turns out it's like an onion with millions of layers,
    and we're sick and tired of looking at layers, then that's the way it
    is....My interest in science is to simply find out more about the world,
    and the more I find out the better it is. I like to find out.""

  26. You can debate the relative "importance" of literature and inquiry of nature, but if you find the first thing a child says as superior to physics, you might need to find a new blog to read.

    The SM is the most successful, explanatory, predictive theory along side evolution we have.

    On the physics side the mathematics to results confirmation is so far beyond "fail" you might start expecting brain to fall through your body to the center of the earth.

  27. arXiv:hep-ph/9803315
    "We therefore simply assume that these dangerous operators are not induced."

    Why is it a "good science"?

  28. You forgot "Prof", tsk tsk...

  29. It is not a sufficient condition for it to be a good science but it is a necessary condition because good science must *always* make assumptions that produce theory that doesn't contradict the observed data.

    There may be an effect to be described later that explains why this assumption or any other assumption is right. But what's more important is that this assumption may be right and it *must* be right in a theory that describes the real world.

    A general element of a "space of possible theory" contains lots of dangerous effects that would *inevitably* show up as something that doesn't exist in the real world, or at least is extremely rare or weak, and whoever assumes that such "dangerous operators" are included is doing bad science!
    Your understanding of this totally elementary point about *all of science* is upside down.
    Every theory has and must have some assumptions so your implicit suggestion that a theory should make no assumption is preposterous; no assumptions means no theory. Now, a theory that will have too many arbitrary independent assumptions will be unconvincing, especially relatively to potential other theories that make fewer independent assumptions. However, that's a secondary criterion because a theory that won't make assumptions that are needed for it to be compatible with the real data is immediately excluded - it is falsified - and that's much more important (negative) property than its having more assumptions than what someone might light.

  30. Dear Dalpezzo (probably a cousin of Del Pezzo haha), thanks for your comment.

    I do agree that popularization of physics and science generally involves profanization and borders crank condensation but that's not what I was contradicting.

    What I was saying and I am still saying is that string theory has never been "overhyped". String theory - as the whole structure - was always underestimated. Many other things about physics, many less important theories (especially the manifestly wrong ones), and many individual scientists and so on and so on have been overhyped but string theory as the whole structure and body connecting the ideas doesn't belong to this list.

    Yes, the society is fashion-driven but cutting-edge science had never become a real fashion. That's true not only for string theory, it's also true for quantum mechanics or even general relativity and perhaps special relativity - despite the fact that Einstein and other individual physicists *did* become a fashion. But I was talking about the theory itself and you know that I did and you know that it's something different, don't you?

    I don't believe that physicists have strong crowd instincts that are much stronger than mathematicians. In my opinion, physicists since Galileo's times have been the ultiimate templates of independence. Of course, it doesn't apply to anyone and it's more likely to apply to good physicists than bad physicists.

    The topics that excite physicists are nevertheless more unified but that's not because of crowd instincts. It's because physics is studying a much more focused, well-defined question than mathematics - how the real world works? - while mathematics studies what artificial concepts and rules we may invent and what we may say about them. Of course that the latter creates much less unity. I exaggerate here, the most important parts of mathematics are "discovering" what may be considered to be objectively important a pillar underlying maths. But if that's so, then I am convinced that mathematicians will tend to think as coherently as physicists.

    I don't think it's possible to easily answer the Yes/No question whether physicists are intrinsically theologians or philosophers. Physics depends on the subtle balance between cold hard experimental data and hot far-reaching ambitions and philosophies. If this balance is violated, physics deteriorates into botany or philosophy, respectively. But both of these modes of dealing with information are clearly needed. The construction and selection of theories in physics obviously *is* a form of philosophy or religion, one that differs from conventional religions and philosophies by using indisputable rigorous enough mathematical, logical, and experimental arguments to support the theories - and this principle that these tools are important is being "worshiped" which is a special feature of physics as a religion or philosophy.

    People who are doing bad physics generally don't use these "worshiped" tools to decide sufficiently important questions or they do errors while doing that. I don't know whether it makes them more or less "religious or philosophical". It depends how you define religion or philosophy.

    Tides are changing but again, there's never been a general tide in the society that would overestimate cutting-edge science. You're living in a fantasyland.

    Good funding isn't necessary for various individual scientists and thank for them but it is surely necessary in the big picture because most of good science is still a lot of hard work and a lot of hard work is only done well if it is appropriately compensated.


  31. Dear Daniel, first of all, I obviously think that it's appropriate for *everyone* who may honestly be called a string theorist to become a professor and for the society to arrange things in this way. By an honest claim of being a string theorist, I mean someone who has mastered the required knowledge up to basic textbook stuff of string theory and who can do research and is willing to do research.

    People belonging to this set are surely among the 1% of the world's smartest people and they have spent 5-20 years by studying that is needed for them to become string theorists. They could have fell out of the train at dozens of places but they haven't.

    I even think that all people who can run 100 meters below 10 seconds could be employed as professional sprinters even though they didn't have to work at all, their IQ may be closer to 50 than to string theorists' IQ, and they will be getting higher salaries than the best string theorists. ;-)

    The number of string theorists as defined by conditions similar to those above is, in the world, something like 2,000. Counting by density of civilization/science, the U.S. may be close to 1/4 of the world (although it's just 1/20 of the population) so there should be 500 string theory professors in the U.S. or 10 per average state. In the same way, Czechia is 1/200 of the civilized world so there should also be 10 string theory professors here. Of course, our number is vastly smaller than that and I am ashamed of this fact.

    The 2,000 world's people who should be string theory professors would be getting a total salary - it's usually lower outside the U.S. - of $100,000 per professor which still gives $200 million per year only. It's like four parts per million of the world's GDP. If someone is telling me that the world shouldn't pay this fraction of its GDP for cutting-edge physics, then sorry, I consider him an uncultural barbarian who may be treated on par with other animals. He or she is just not a full-fledged human being in my eyes, sorry.

  32. "There are compactifications of string theory that have the Standard Model field content at low energies, after SUSY breaking (below all these other scales of new physics)."
    Do you mean generically three families and correct gauge group or did someone get to tune fluxes etc. to also get the correct mass spectrum&couplings?
    Honest question, I'm not trolling: unlike most people, I actually turned to hard-core believer as soon as the whole flux compactification/landscape business came out...

  33. Hi Daniel,

    How in the world did you come to the conclusion that the "Meta discussions" are "interesting"?

    They are very unfair and destructive! If it is as you say, that new string theory professors do no longer get a postition, this is a very very sad sign that the sourballs and trolls, who want to completely abolish and forbid string theory and everything related to it, are getting successful and have taken over now :-(((

    I hope that the Milner Prize can somehow help to avoid this horrible nightmare szenario the trolls and sourballs violently and forcefully try to achieve by their unfair and dishonest propaganda campains everywhere in the media ...

  34. Feynman : the genius who has never been affraid to speak his mind freely.He belongs to my top 5 physicist of all time.But,if I'm not mistaken, he said once he wasn't much fond of string theory?

  35. Hi, tx for your question. First, I definitely do mean that there exist models with the exact MSSM spectrum and nothing else, see e.g.

    In general, that may be broken to the SM although the question whether this model or any other model produces a viable SUSY breaking scale and other things is open.

    Second, I don't have a proof that one of them has exactly the right values of all the couplings. But there's no proof that there's no right model with the right couplings, either. What we can do is to extract the low-energy effective theories from the string compactifications and, because we know that the precise couplings are undetermined, use the effective QFTs as a general summary of all the string models.

    From a predictive viewpoint, they're equivalent until we may actually fully determine what combinations of the parameters are allowed in string theory and what combinations are not. Quantum field theory doesn't predict the precise value, either, so my point is that it's invalid to pretend that string theory is worse off here. It's exactly at the same level as the QFT framework until the precise values of parameters may be listed and compared; and if and when they will be listed and compared, one may either disprove string theory or show that it agrees with the world much more nontrivially and accurately than a QFT because it also predicts the values of the parameters, at least from a discrete set of choices. At this moment, we only know that QFT doesn't even have the potential for this final step while string theory does.

  36. Those operators are common feature of EFT. They should be absent in a full theory of course, but full theory is unknown. So either you use that EFT only below electroweak scale OR you should deal with "dangerous operators", not simply drop them out. Sorry, maybe this thing was discussed by Nima and others thousand times, I just want to understand why this assumption is allowable. In the paper there is at least one more assumption about extra dimensions. This is rather common style in hep-th, to make several assumptions at once, then to find some "effect" and wait for grants and prizes. How about the rule, that in one paper you should use only one assumption, at least one "strong" assumption?

  37. That was a very informative reply, thanks.

    Although, I think Feynmans point still has some merit, perhaps not in actual layers but in details. It will become "uninteresting" to people who study physics.

    As long as there are questions to answer, people are going to try to solve them. Though at some point we will reach that "uninteresting point" or a TOE. Not that I'm implying that we are there or saying when it might be, but there seem to be the only two options.

    When reading him say that it stuck with me. its such a great honest quote, with all his false modesty :)

    Also signaling the point where just so philosophy tales will rule because there is no science left to distinguish between them.

    Its a very good description of what science is, for something that is hard to define well.

  38. Dear Dilaton, hope your eyes are doing better. Take care of yourself, get plenty of rest :)

  39. Dear Layman, your proposed quota ("rule") on the number of assumptions is utterly childish, especially if the limit is supposed to be one.

    A typical paper that has a chance to be both right and new has to make at least a dozen of assumptions - although it's not really a well-defined task to accurately count them.

    Moreover, you implicitly suggest that the legitimate measure would be just to count the assumptions in terms of an integer. That's also silly because some assumptions are more plausible and less contrived than others.

    There may be many models or guesses and of course that their very large number is itself a sufficient way to see that the average probability of each model to be right is low. But there are still models that are either more important or more likely to be true or more original than others (or models in the history of science that have proven to be right) and such models still make a dozen or dozens of assumptions.

    Every quantum field theory, to be realistic, must assume that some operators are absent or negligible "by hand" or it must assume that there's a new sector of particles that naturally enforces the vanishing of those operators - and with contrived enough new hidden sectors, this path may become as contrived as simply assuming that the operators are absent.

    Be sure that if you abandoned all papers that make at least two assumptions, you would throw all of science into the trash can.

  40. "[] the reason why I "believe" the answer is Yes is that string theory nontrivially agrees with so many features of the real world (and nontrivially avoids

    so many potential traps) that could have been wrong that I can't imagine what the role of this theoretical structure would be if it weren't describing the

    real world."
    Wow, what a poetic declaration of Platonism! :)
    Anyway, it's funny how the critics belonging to the "not-falsifiable" species don't get the point that O(10^500) options (just to quote the traditional would-be superhuge number) are not really that much when you have to match O(100) continuous parameters: even assuming just linear scales you can expect a random agreement of at most a fraction of a percent...
    The theory IS so obviously falsifiable (in principle, of course)

  41. Exactly, 10^{500} is really not that high. Most of this high number of compactifications lead to effective QFTs with O(100) low-energy parameters so one only gets 5 digits for each parameter. We measure some parameters more accurately than that so the theory seems to be predictive even at the current precision - of course, the missing detail is the complete list of all the low-energy effective QFTs and the precise values of parameters that follow from string theory. ;-)

    As always, I don't believe that our Universe belongs among the "most generic" compactifications. It's bound to be much more special nd the number of "special" compactifications is vastly smaller. So I wouldn't care even if the number of compactifications were countable and infinite. In fact, it's really remarkable if the number of "vaguely semirealistic" models is finite, and it still seems to be the case.

  42. My younger cousin, a math graduate from Prague quipped about Milner Prize - " there you see it, what is better ? Finishing the school, then work for 10-20 years and maybe one day you may get a prize of some sort, or drop out of school and make lots of money".. he had a point - I took the latter route early on in life... Of course a disadvantage of so doing is that one has a lot of catching up to do later on. :-)

  43. Lubos writes:
    "The era when the deepest new insights about the Universe could have been obtained without string theory had already ended several decades ago."
    You sure about this ending remark? How do you explain all those pictures of UFO's that people all over the world have taken with their cell phone and the witnessing of human levitation by highly credible observers throughout the centuries.
    One of the purposes of string theory is to unite gravity theory with quantum theory. If this fantastic notion that mass has some "innate, inherent" ability of mass to either attract mass or warp space" is brought into question by inexpensive table top experiments that can be repeated by others, then string theory in the future will not have much of a leg to stand on.

  44. On this, I think I disagree, in a way (if I get correctly what you mean by "most generic"). The landscape got me excited because the pattern of SM structure&parameters actually looks random and generic, so I don't see any reason why "our" landscape minimum should be special from a "godly" point of view, say, for beeing in a particularly symmetrical point of whatever parametrizes the landscape (while it is
    obviously true that the generic point will unviable, because of the likely huge CC, for instance).
    ... but at present I guess it is more or less a matter of taste...

    Thanks for your answers, and let me say that you are doing an amazing job with your blog!

  45. Thanks for the nice words Eugene :-), it is quite ok now.

  46. The problem, you see, is that everyone is born wanting to be special. But everyone can't be special -- or at least remain so once they leave home.

    Maybe it would help if the few who remain special reported back that it ain't all its cracked up to be. Even if they were lying. ;)

  47. Fascinating as usual. I particularly like your talking about coherence of focus among a subject matter's researchers instead merely of seeming "size" of a research field's subject matter. I wish i had thought of it.

    You said,
    I exaggerate here, the most important parts of mathematics are
    "discovering" what may be considered to be objectively important a
    pillar underlying maths. But if that's so, then I am convinced that
    mathematicians will tend to think as coherently as physicists.

    Math is a very big field, studying everything directly or indirectly
    imaginable. The comparison perhaps ought to be not that of mathematics
    to physics alone but instead that of mathematics to all the
    sciences/studies of things directly or indirectly perceivable (i.e.,
    where at least evidence is perceivable, concretely observable) -
    physical, chemical, biological sciences, and human/social studies. In
    that perspective the idea that mathematicians discover objective
    relationships or "true facts about imaginary objects" doesn't imply that
    mathematicians collectively will be as coherently focused in terms of
    subject matter as physicists are.

    One might object that that comparison
    is wrong because it is between things too dissimilar in the sense that,
    among mathematical disciplines, one doesn't find a series with the kind
    of decrease of rigor and solidity that one sees in a series that
    terminates with human/social studies. But mathematics draws deductive
    conclusions, while the sciences mentioned draw non-deductive
    conclusions, which, even if all their premisses were all true and if all their reasoning were good, would still vary in
    security in a way that valid deductive conclusions from consistent hypothetical assumptions about imaginary objects do not.

    Well, anyway, if that's not convincing, still I think it's a better bet to put mathematics and the set of said sciences on the same taxical level, as one might do with imagination and perception (concrete observation) and with deductive and non-deductive, and it does better fit with differences in the coherence of focus. .

  48. Hi Lubos, I would like to ask a question. Why do you think that string theory must be the real theory of quantum gravity? I know that the QFT of gravity is perturbatively non renormalisable and string theory can cure this problem, but isn't there other possibilities?

    I have two ideas:
    1) Maybe another infinite tower of particles can cure the UV problem in perturbation theory, which leads to an alternative theory, and you need experiments to choose.
    2) Maybe general relativity + standard model has a non Gaussian UV fixed point which cannot be seen in perturbation theory. Since we don't really understand strongly interacting, nonperturbative QFTs, I think we cannot exclude this.

    Can string theorists offer some arguments agains these alternative possibilities? Peter Woit always talks about experimental verification, but I think that if you can convincingly exlude 1) and 2), than string theory is proved even without experiments.

    Thank you in advance!

  49. Dear Rezso, I don't have a quite complete proof that string theory has to be the right unifying theory but my reasons why I feel certain it's the case is standing on two legs:

    * it's a theory that implies all classes of physical phenomena we know in Nature out of a more unified starting point i.e. even though it doesn't assume them; it has avoided all inconsistencies and passed all the tests of comparisons with experiments - because it implies so many general things, it could have been excluded a long time ago if it were wrong; it's hard to imagine that such a structure exists and is so similar to the reality but it's not the same thing

    * in particular setups, one may literally prove that the right consistent completion of a theory of quantum gravity has to have all the features of string theory. This may be done e.g. in the case of 11-dimensional supergravity.

    If you want to generalize the 2nd kind of proof for general backgrounds, it's hard, in particular because we don't have a full definition of "string theory" in the most general sense. So when an infinite tower of new excited states of "something" looks superficially different from string theory, it's not yet a proof that it isn't string theory. String theory is able to behave in various ways and they may often be equivalent to each other although the equivalence is far from obvious.

    Of course that I agree with you that it's another legitimate strategy to be proving or disproving string theory, different from attempts to directly test it which doesn't seem so promising an approach for string theory or any other theory of quantum gravity.

  50. Ahm Lumo (or somebody else),

    do you know if something is wrong with Matt Strassler now ...? He has posted not a single letter on his site since August 15th.
    This seems strange to me, since he always used to say it there, if he will be too busy, away, etc to frequently update the blog or respond to questions etc.
    And I think if he does no longer want to continue his site for some reason, he would at least announce this too (as some kind of a last message?) ...

  51. Dear Dilaton, there is a risk of overinterpreting here. I know tons of physics blogs that, at some moment, run into the rhythm that they're updated once in a month etc.

    David Berenstein's blog

    was last updated on July 4th - Higgs discovery, short report - and I don't even mention that it's actually blog of David Berenstein *and* Moshe Rozali who hasn't posted for years now.

    You could be given lots of examples. I think readers never have any true guarantee of "regular enough" updates...

  52. Dear Lumo, you are right:

    I've observed now a minor reorganization of the articles over there that decreases the entropy of the site ... Such a thing can, according to the second law of thermodynamics, not happen spontaneously without the action of external (MS) factors :-D

  53. I changed my mind. These awards are a good thing. My initial reaction was just dumb.

  54. You, sir, are incredibly arrogant and vastly overestimating your importance and the importance of string theory.