Witten on “The Future of String Theory”

Witten’s talk this morning at the KITP on “The Future of String Theory” is now available. He only talked for about fifteen minutes and then took some questions. I thought it was a rather weird performance. Not only did Witten not really have anything to say about the future of string theory, he didn’t even discuss the present state of the theory. The most recent thing about string theory he mentioned is the now seven year-old AdS/CFT correspondence. He drew the standard picture of Feynman diagram vs. string world-sheet, claiming it indicates that space-time is an “emergent phenomenon”. He even noted that he has been drawing the same picture for nearly twenty years now and he still doesn’t know in what sense this “emergent space-time” idea is true, although AdS/CFT is the closest thing to the kind of thing he is looking for. Now not only space-time is supposed to be “emergent”, but so is the string itself, although he admits he doesn’t know what this means.

Instead of looking optimistically to the future, Witten’s talk was extremely defensive. He started off trying to defend why string theorists work on string theory (basically because it is a non-trivial extension of QFT, contains gravity and has lead to important mathematical results). Much of his very short talk was taken up by mentioning criticisms of string theory and giving unconvincing responses to them. He didn’t say anything in the bulk of his talk about the Landscape or twistor string theory, or anything else going on these days in the field.

There were several questions from the audience. Someone asked him if he would still believe as strongly in string theory if the LHC didn’t find supersymmetry. He somewhat evaded the question, saying he would be less optimistic about how well we can ever understand the world, but implying that he wouldn’t consider this as evidence against string theory itself, repeating the same defense of why he did string theory that his talk started with.

The last question was about the anthropic principle and the Landscape. He began his answer with something like “Well…..(nervous laughter)… uh…..” then finally said more or less “I’d be happy if it is not right, but there are serious arguments for it, and I don’t have any serious arguments against it.” So I guess he comes down on the Weinberg side (“I don’t like it, but maybe we have to accept that our fundamental theory can’t explain any of the things it is supposed to”) vs. the Gross side (“people who think this way have given up doing physics”).

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32 Responses to Witten on “The Future of String Theory”

  1. D R Lunsford says:

    Everyone knows that gauge invariance requires experimental support to be massless.

  2. Chris W. says:

    ..and, in light of the string theory landscape it is unclear what “massive experimental support” could ever mean. The landscape’s partisans seem to be thrilled that it might contain a hill or valley that resembles whatever observations one might anticipate making.

    Even discounting the landscape, the profligate mathematical richness of string theory is a liability (and a distraction), not an asset. The theory doesn’t appear to make any new experimental meaningful statements of the form “X can never happen”, “X will never be observed”, or “X must happen in situation Y”. Cocky and dangerous predictions like that are what make a theory truly testable. To make them, string theory will have to become a very different sort of theory than the one we now have. That won’t happen unless its practitioners make a deep commitment to making it happen. I don’t sense such a commitment or the kind of active and imaginative critical effort it produces.

  3. Thomas Larsson says:

    If you were Witten, what would you do to “fix up” string theory as it’s known today (besides fixing up diffeomorphism anomalies)?
    What would convince you to change your mind and be in support of string theory?

    In the unlikely event that string theory acquired massive experimental support, I guess that I would have to believe in it. But the present situation is rather the opposite.

    The construction of a quantum theory with some prescribed symmetries is, from my perspective, the same thing a constructing the representation theory of the group of symmetries. There is really a 1-1 correspondence:
    1. Given a quantum theory, its symmetry group acts by a unitary representation on the Hilbert space.
    2. Given a unitary representation of some group, the Hilbert space on which it acts is the Hilbert space of some quantum theory.

    In particular, the Hilbert spaces of the fully interacting gauge-invariant or diff-invariant theories carry unitary representation of the groups of gauge transformations and diffeomorphisms. Perhaps one should factor out gauge symmetries, although I don’t see why – it is definitely not necessary for consistency (unitarity). But this is really irrelevant for the argument. The anomalies must be there at least before factoring them out, so if you cannot write down the anomalies in the first place, you lose.

    I am pretty sure that there is no way to fix string theory. The representations look the way they do, and their Hilbert spaces look rather like fixed versions of field theory. I don’t see any way to “fix” SU(2) to allow for unitary spin-1/4 representations either.

    I don’t have a clue what I would do if I were Witten, and I don’t really care. It’s not my problem.

  4. Peter says:

    Some comments about Arun’s questions #2 and #3.

    There are two main ways people have tried to relate string theory (whatever it is…) to real-world physics. The first, and in some sense the oldest, is the idea that it provides a dual formulation of gauge theories like QCD. The latest version of this is the AdS/CFT correspondence, which some string theorists go so far as to take as an answer to the “What is string theory” question, defining string theory in terms of a QFT. I don’t have any problem with this. It is a promising way to learn more about gauge theories like QCD, worth investigating and may lead both to better understanding of how to calculate things in QCD, as well as to a better answer to the question of what string theory really is and what it is good for.

    The second way people try to relate string theory and the real world is the one that has got the most attention over the past 20 years, and it’s the one that I think is completely misguided. This is the idea that one can use anomaly cancellation conditions to pick out one or more supersymmetric theories in 10 or 11 dimensions with specified gauge groups, and that this will give a theory of everything. There are two separate kinds of arguments against this, besides the operational one of 20 years of failure to get anywhere.

    1. Nothing comes out right: We live in 4 dimensions, gauge group SU(3)xSU(2)XU(1), non-supersymmetric particle spectrum. String theory predicts none of these things. If anything, anomaly cancellation predicts 10 dimensions, E8xE8 or SO(32), supersymmetric spectrum. To get things to look like physics you need to engage in complicated, ugly, ad hoc constructions (latest example is KKLT) that completely ruin any predictive power of the theory. This is extremely strong and convincing evidence that the initial idea is simply wrong. I don’t understand why people refuse to admit this.

    2. There is no good non-perturbative formulation that does what you want. The great dream of the subject is that there is some beautiful 11d theory based on some elegant principle that, once it is found, will automagically solve the problems in 1. I think there is zero evidence for this despite 20 years of effort, and at this point the people who go on about this are simply engaging in wishful thinking. Witten, Gross and others at some point need to either put up or shut up about this. If for twenty years now they haven’t been able to find this wondrous new principle, they should admit it probably doesn’t exist and do something else with their lives. The fact of the matter is that, mathematically, the standard model involves far deeper and more elegant mathematics than that used in string theory.

  5. JC says:

    Thomas,

    If you were Witten, what would you do to “fix up” string theory as it’s known today (besides fixing up diffeomorphism anomalies)?

    What would convince you to change your mind and be in support of string theory?

  6. Thomas Larsson says:

    #2. he expands later to “What is the core idea analogous to the principle of equivalence in the case of general relativity?”
    #3. he expands later to “Even if it occurs {i.e., we understand what string theory is}, and if string theory is on the right track, will we be able to learn how to use it to understand nature?”

    But it seems that Peter thinks that #2 is also dubious? I had thought that while the final answers for #2 are not available yet, there is little doubt that there is something there; in fact the seeming wealth in an answer to #2 is why physicists study string theory, and why we have strong opinions that #3 will be answered in the affirmative.

    Given that Witten and hundreds more of the world’s brightest people have spent 20 years on #2 and still haven’t figured it out, why do you believe that there is something there? And even if there is something, who will figure it out, when Witten obviously wasn’t smart enough?

    Witten may well be the smartest person since Aristotle, but that doesn’t mean that Wittensian gravity is more successful than Aristotelian gravity. Besides, Witten at 55 is probably less smart than Witten at 35.

    It is almost a theorem that string theory will fail. It doesn’t account for the diffeomorphism anomalies in 4D which must be there in canonical quantization by analogy with the conformal anomaly on the worldsheet. Anomalies are non-negotiable things, and if your theory cannot describe all necessary anomalies, it is in deep trouble.

  7. Arun says:

    Don’t let physicists, too, fall into the slick slide trap!

  8. Lubo Motl says:

    I agree – industry seems to be a decade ahead of the physicists in presentations. The mathematicians, on the other hand, have not invented the overhead projector yet, and therefore they always prefer the blackboard.

    Well, some of us are trying ;-), see

    http://schwinger.harvard.edu/~motl/twistors.ppt
    http://schwinger.harvard.edu/~motl/rutgers-talk.ppt

  9. Fabio says:

    Wow. Looking over some of the slides from the talks, the thing that impresses me most is how primitive they look (with the exception of t’Hooft’s). Having been in industry for a decade or so I was sort of surprised to see that people would still scribble things on transparencies with markers for a conference talk. It’s kind of quaint.

  10. Arun says:

    Just watched Gross’s talk, very worth watching.

    Witten had three questions at the start of his talk:

    1. Why do physicists work on string theory?
    2. What is string theory?
    3. Can we connect string theory to particle physics?

    #2. he expands later to “What is the core idea analogous to the principle of equivalence in the case of general relativity?”

    #3. he expands later to “Even if it occurs {i.e., we understand what string theory is}, and if string theory is on the right track, will we be able to learn how to use it to understand nature?”

    I had understood Peter’s criticism of string theory to be basically centered on #3, i.e., his stand is that the connection of string theory to nature has been tenuous all through its history, and the situation shows no signs of improving. And if #3. has no good answer, then #1. needs an answer – why should physicists work on it?

    But it seems that Peter thinks that #2 is also dubious? I had thought that while the final answers for #2 are not available yet, there is little doubt that there is something there; in fact the seeming wealth in an answer to #2 is why physicists study string theory, and why we have strong opinions that #3 will be answered in the affirmative.

    I think asking the question #3 in the form of “what experimental results or observations in the next 10 years will help us decide whether string theory is relevant?” can be a useful scientific exercise; while attacking #2. is a waste of time.

    -Arun

  11. Lubos Motl says:

    Dear Arun,

    the emergent time is a great question – David Gross was exactly mentioning this puzzle in his talk at KITP.

    Special relativity guraantees that if space is emergent, time must be emergent as well.

    String theory in various formulations is Lorentz-invariant, and therefore it should agree with this principle.

    However the specific formulations we have are able to show that *space* is emergent, but time is never emergent in these pictures. Well, if you have operators or wavefunctions or whatever, and even if you want to predict the future from the past, you need a concept of time.

    It’s not a contradiction. The manipulations that we are able to make with the space cannot be easily done with time – time is different in details, at the end, for example it can have an arrow (time-like intervals have a universal arrow, past vs. future, while spacelike intervals don’t).

    If one says that time is emergent, the idea of predicting the future from the past must be approximate and emergent as well. Well, it’s not shocking if we study the S-matrix: it is the set of amplitudes between the infinite past and infinite future, and with infinite separation, time becomes sharp and well-defined much like space.

    If we look at the gauge-fixed descriptions, such as the light cone gauge ones (Matrix theory, for example), the gauge-fixing always guarantees that there is a well-defined notion of time, and the other operators are simply functions of it.

    There have been speculations, e.g. by Aharony and Banks, see

    http://arxiv.org/abs/hep-th/9812237

    that M-theory – and little string theory in particular – has some inherent non-locality in time. But these conclusions have not been universally accepted yet, I would say.

    A few more comments: if you adopt the formalism of the S-matrix, the questions go away – the only invariant object is the amplitude at infinite separations both in space and time, and these emergent notions are “emerged fully” anyway.

    However, the S-matrix is not enough to study cosmology. If we want to understand the early cosmology, it seems sort of necessary (or useful) to understand in what sense the time emerges after the Big Bang. It probably does not make sense to ask what was “before the Big Bang” or “before the Universe was Planckian in size” – because before this moment, the concept of time (and the word “before”) had not emerged yet. Nevertheless there is a clear feeling that something is missing, and we should be able to say something about “which universes can emerge” from the Big-Bang and which cannot. And the answer about this Planckian super-early cosmology seems to require us to learn HOW time can be emerging and what is it emerging from.

    Best
    Lubos

  12. Arun says:

    Lubos,

    It helps a bit. Let me ask: is the notion of time – smoothly flowing, continuous – essential to any formulation of string theory, or will it emerge out of string theory? Does the notion of time exist in quantum foam/quantum geometry?

    -Arun

  13. Lubos Motl says:

    Gross’s talk is very cool! Highly recommended.

  14. Lubos Motl says:

    Hi Chris,

    thanks for your comment. Was this blog meant to debunk the subject? 🙂 Well, I think that this purpose belongs to the past. I view it as a place for philosophizing about some general questions of string theory and theoretical physics and its future, and especially about the importance of various ideas.

    But if one looks at this blog, it is rather obvious that string theory *is* the most important set of ideas we have. Look at the percentage of the postings dedicated to the subject. 😉 Well, there are some essays by Peter that are just anti-stringy and that are “not even wrong”, but this is just a natural component of this blog. This blog is not a refereed journal. Nevertheless, I think that there are also some entries in this blog that do have a meaningful content.

    All the best
    Lubos

  15. Lubos Motl says:

    We have an overwhelming evidence that specetime is an emergent phenomenon. It is not just some Witten’s progressive idea, it is an idea that even Brian Greene always says for the popular audience.

    The statement means that we should not think about the objects and events to take place on a well-defined background geometry. Quantum mechanics guarantees that the concept of completely smooth geometry is incompatible with quantum mechanics that make things fluctuate.

    But string theory goes much further. Geometric descriptions, such as general relativity, are only approximations valid at very long distances. At very short distances, comparable to the “length of the string” (string scale) or “the smallest meaningful black hole” (the Planck scale), physics does not admit a simple description in terms of usual geometry. Geometry is generalized to something much bigger, and the difference between geometry and matter disappears – this is the content of unification of gravity with other forces and matter.

    String theory implies a lot of dualities. For example, T-duality shows that the Universe with a circular dimension of radius R is physically indistinguishable from the universe with a circular dimension L^2/R, where L is the constant length associated with the strings (string scale). A radius smaller than L has identical physics as the inverse radius which is greater than L. If one compares these two equivalent universes, one must create a dictionary: for example, objects with momentum N/R in the “small” Universe map to string that are wound N times around the circle of the large Universe, and vice versa.

    The momentum is the generator of translations, and you can see above that it behaves physically in the same way as the winding number (how many times a string is wrapped). It is just a matter of convenience whether we call something “momentum” or a “winding number” in these Universes with circular dimensions. Also, mirror symmetry analogously relates two very different 6-dimensional shapes (mirror duals) which nevertheless lead to identical physics if you put string theory on it.

    The momenta etc. can have the interpretation of winding numbers, electric charges, and so on, in various equivalent descriptions of the reality. Different equivalent descriptions of reality do not agree what the spacetime geometry is. One of them can become much more reasonable than others, but it is only in the case in which the radii and size of this geometry are much greater than the fundamental scale (for example the string scale). In this case, one geometry is much more realistic and convenient description than others. But because I need the size of the geometry to be large, geometry is just an emergent phenomenon.

    At very short distances comparable to the fundamental scale, geometry is replaced by a generalized, quantum, stringy geometry that contains much more stuff that we don’t usually consider to be “geometry”. Geometry becomes unseparable from other physical concepts, objects and phenomena.

    The notion of topology of the space(time) manifold also makes sense as the approximation in the limit where we study the long-distance behavior only. At very short distances, quantum mechanics guarantees that even the topology is fluctuating (quantum foam) – one can imagine that the geometry at very short distances is non-commutative, although one must be ready that the word “non-commutative” in the most general situation must be extended and generalized.

    Non-commutative geometry is something that allows one to replace functions on a manifold by discrete matrices – the smooth, commutative geometry appears for very large matrices.

    Much like in the naive discrete approaches to quantum gravity (such as “loop quantum gravity”), the character of the spacetime is very different if we probe it with a very good resolution. However, the effects in string theory are not just that “space is made of atoms of space”. Instead, there are many new objects, fields, concepts appearing in this regime and all of them are “fuzzy” and mixed up in some way.

    Does it illuminate the question?

  16. Chris Oakley says:

    If there is a source of disappointment, it’s the fact that the hundreds of smart people – old and renowned ones as well as the young ones – have not been able to make greater progress in the recent years.

    Lubo, I am glad that I am able to agree with you on something for once. What is the world coming to? The chief bodyguard of the superstring orthodoxy posts comments on a web log devoted to debunking the subject – ? Maybe that is a reflection of the state of affairs in fundamental physics – that we have to huddle together to protect ourselves from the greater threat of all becoming irrelevant.

  17. Arun says:

    “Space-time is an emergent phenomenon” – while even Witten doesn’t know what it actually means, what could it conceivably mean?

  18. Lubo Motl says:

    Wilczek’s talk is very funny – he says that he will not allow his first Nobel prize to… Well, you should see it.

  19. Lubo Motl says:

    I think that Witten’s talk is good and pretty optimistic! What are you talking about, Peter? Yes, it is a rather standard talk about uniqueness in quantum field theory and string theory, and about richness of string theory (underestimated even by the enthusiasts, as Witten points out), and about the stringy counterparts of the principles of GR, and what is string theory – and it does not cover the newest developments, but it is announced in the very first sentence, and this orientation of the talk is probably determined by the audience. I would almost certainly give him an “A” for this talk. 😉

    I also think that his answers were very honest. If they ask him how (non)-SUSY on the LHC will affect him, he is realistic and talks in terms of “level of belief” and probabilities. Whoever expects some radical statements that one experiment will change totally everything about his belief system, does not really appreciate the huge number of very different rational reasons and insights behind Witten’s opinions.

    Dear DRL, I have no idea what you find astonishing and infuriating. Maybe you misunderstood something? We just said that Witten is not pessimistic about string theory itself – that has displayed no real problems with its framework – but about the limited human abilities to study it, which have slowed down the progress in recent years, and it is not completely clear (and it is a matter of hopes) whether we will be able to do better in the future.

    At any rate, it is an objective fact that the progress in string theory today is slower than in the middle of 1980s or middle of 1990s. One more thing about the intelligence of string theory vs. the intelligence of us: string theory is much smarter than all of us – me, you, but also Andy Strominger, Cumrun Vafa, or Edward Witten. I am sure that all of them – maybe except for you, DRL – would fully agree with this statement of mine, and some of them have said this statement themselves. You’re probably the only one who thinks that he is smarter than string theory – but this is, I apologize for being honest, a symptom of limited intelligence, not high intelligence. And if you ask why I feel the moral right to conjecture such things about you because of this single topic, it’s because I have known you for quite a while, so this judgement is not just because of this specific question!

    If there is a source of disappointment, it’s the fact that the hundreds of smart people – old and renowned ones as well as the young ones – have not been able to make greater progress in the recent years.

  20. D R Lunsford says:

    Lubos, I find a statement like that both astonishing and infuriating. Who the hell are you to make statements about any single PERSON’s intelligence, not to say the whole shebang? Not only do you claim to read God’s mind, you know what he has in store for poor suffering Man.

    I would not only be embarrassed to be credited with such a statement, I would be ashamed.

    -drl

  21. Lubos Motl says:

    I agree that Witten’s limited optimism stems from the limited human intelligence, not from defects in string theory. In some sense, there is a disappointment that all of us have not been able to go much further.

    Brian Greene’s TV example with the dog learning GR is very cute, but I still hope that despite the finite brains of all of us, we have some abilities to crack anything that makes sense in the future.

  22. Lubos Motl says:

    I don’t believe that reasonable professional physicists believe that the principle of equivalence is unimportant as a foundation of GR. (Did the comment mean Hawking?)

    Weinberg has been criticized for not sharing the “religious geometric” viewpoint about general relativity. But Weinberg’s point is certainly not that the equivalence principle – or diffeomorphism invariance – is not important.

    Weinberg’s point – and I am sure that this is shared by an overwhelming majority of particle physicists and string theorists – is that general covariance is different in details, but otherwise it can (and it should) be treated with the same tools as other gauge invariances such as Yang-Mills invariance. Well, string theory unifies these two naturally in many “senses”. 😉 Already the Kaluza-Klein theory unifies them, and string theory goes much further.

    The special feature of gravity is only in its low energy manifestations – spin 2 fields and particles; coupling to stress energy tensor; geometrical interpretation of the gauge invariance. But these are just visual differences. In the fundamental way, gravity is not that different, which is why it can be unified.

  23. Anonymous says:

    To be fair, Witten was talking to an audience who hadn’t even heard of Ads/CFT, so you could not expect much. Two things stood out from the talk though: first, people like Witten *still* believe that the Principle of Equivalence is somehow the foundation of GR. People in that field stopped believing that decades ago [hint: search for the POE in Hawking and Ellis’ book —from 1973!]. Second, Witten points out that the *real* reason Ads/CFT is interesting is because it might give us a dual to the actual spacetime in which we live. It’s great that he says this. It would be even greater if people took his words to heart and actually tried to apply Ads/CFT in that way. I don’t think that anyone really believes that *our* spacetime fails to be globally hyperbolic on cosmological scales, do they?

  24. Chris Oakley says:

    Following on from Danny’s comments – though less eloquently – I knew that I had no future in the subject just from the kind of casual discussions I was having with my peers 19 years ago. I was a harsh critic, and remain a harsh critic, of things I perceived as inconsistencies in QFT. I worked on the principle that one should wipe one’s bottom before thinking about powdering one’s nose, which automatically ruled out spending time on grandoise super-unified schemes before basic mathematical problems were solved. None of my colleagues agreed with me on this, and when I would dismiss their string theoretical efforts as unmotivated and overly speculative they would take on the appearance and vocabulary of religious fanatics prepared to sacrifice all for some inexplicable but strongly-held set of beliefs. They are still doing it.

    Fine … but don’t pretend it’s science.

  25. D R Lunsford says:

    Perhaps it is the recognition of hubris in himself and others. After all, what string theory proposed was 1) a revision of Democritus, thus a supposed “new beginning” for science 2) an abandonment of the essential idea of indentical particles and their statistics 3) a deliberate willful disregard of the scientific method in favor of a mediaeval-scholastic imposition of a false order – a return to “reading God’s mind” 4) A PR campaign on the level of the Neocons to convince everyone that strings beget gravity, when this was never in fact true.

    Wouldn’t you be depressed to look in the mirror and know you took part in such a shell game – such a carnival ruse?

    In a larger sense, the intellectual climate in the West seems utterly poisoned by fashion and faddery. Facts and imagination are so pre-post-modern.

  26. String Theorist says:

    Witten’s disillusionment stems not from any defect in string theory itself, but from the limitation of human intelligence.

    String theory exists, regardless of one’s prejudices, and the question of whether the landscape exists is a scientific question, regardless of one’s prejudices. (It is the question of what to DO about the landscape, if indeed it exists, that some people like to answer non-scientifically.)

    We can’t expect a dog to understand quantum mechanics, and it may be that we are reaching the limit of what humans can understand about string theory. Maybe there are advanced civilizations out there to whom we appear as smart as dogs do to us, and maybe they have figured out string theory well enough to have moved on to a better theory…

  27. Peter says:

    I know that Witten has been somewhat discouraged about string theory for a while, but still doesn’t want to give up on it. Under the circumstances I would have been a lot happier to hear him say something like “things are discouraging for the following reasons, but I still continue to have hope for these other reasons. To continue to be viable, string theory needs to make progress on the following problems, and here are some ideas about them. What Susskind is suggesting about the Landscape is not science and I’d abandon the idea of string theory before going down that path”.

    In other words, I wish he had come down on Gross’s side of the Landscape argument.

  28. Lubos Motl says:

    I am surprised that Peter Woit is surprised to see that Edward Witten and perhaps some others feel slightly disillusioned today. I thought that you, Peter, were following what’s going on in psychology of our field, and you were even comparing the citations of the most cited articles in 2003 and 1996, for example. 😉 Yes, it’s much less today, and our optimism is correlated with that, of course. It does not apply to some people ;-).

    Witten would certainly like some experimental confirmation, too. Also, there is a lot of sense in which he deserves at least one Nobel prize, but clearly, without a breakthrough that will allow experimental verifications of predictions, it’s hard to imagine.

    Your description does not suggest that Witten’s talk is something I can’t miss, but because I know in which way you twist, I will try to watch it anyway. 😉

    BTW Bush may have seemed uncertain, defensive, and feeling bad about the reports from Iraq in the first debate, but I think that he was slightly better than Kerry in the second debate.

  29. Peter says:

    I think you’re very right that that’s part of the psychology going on here.

    And I should make clear that I don’t think Witten is a cynic; I think he believes in what he says (although I wouldn’t say the same about our current administration and what they say about Iraq).

  30. JC says:

    Perhaps being in “denial” is a very ingrained human trait, especially when one has invested a lot of time, effort, and pride into a particular endeavor. A very common manifestation of this is in the “sunk cost fallacy” where a person figuratively or literally “throws good money after bad money”. On the stock market, it would be where somebody stayed with a crappy investment hoping to one day make back all the money they “lost” on it. Emotionally it’s very hard for them to “sell” the crappy investment before reaching the break-even point, since selling and taking a capital loss would tell them that their personal judgement was “wrong” about it.

  31. Peter says:

    Witten’s defensive performance reminds me of George Bush being confronted with the fact that the war in Iraq was based on a mistake and the whole thing seems to be going very badly and hasn’t worked out at all as planned. Just like Bush, Witten appears to be unwilling to face up to what a disaster the current situation is, or admit that the whole thing may have been a mistake. Unfortunately, Witten’s sticking to his guns and seeming highly unlikely to ever give up or acknowledge defeat is good for string theory, but bad for physics. If he ever gives up, string theory is doomed, but as he and others refuse to acknowledge what a disaster it is, the field of theoretical physics suffers immensely.

    The way things are going, the endpoint is going to be that theoretical physics will be dominated by the endless study of a horrifically complex and ugly framework that can never explain anything, together with an associated “Landscape” ideology that justifies never having to relate the theory to the real world.

  32. JC says:

    Is this an ominous sign of an eventual day of reckoning for string theory? Or is Witten becoming very cynical about the whole enterprise altogether?

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