The latest Cosmic Log column on msnbc.com concerns Lawrence Krauss’s new book Hiding in the Mirror and the author asked Krauss a question I’m expecting that physicists will be hearing more and more often as time goes on: “Why is string theory science but intelligent design isn’t?”
Krauss gives a response that isn’t completely convincing. He says that “the difference is that Ed Witten and the other good string theorists will, if an experiment comes along that demonstrates that supersymmetry isn’t discovered in a definitive way, be the first to say the theory is wrong.” This isn’t really true. Since the scale of supersymmetry breaking is unknown, one can’t hope to experimentally definitively show supersymmetry is not there. And the question at issue is string theory, not supersymmetry. Will string theorists abandon the theory when supersymmetry is not found at the LHC? We’ll see in a few years, but I already see them hedging their bets and many undoubtedly will not see the lack of supersymmetry at LHC energies as proving string theory wrong.
The behavior of string theorists that Krauss identifies as most like religion is the argument that “the theory is so beautiful it must be true.” I actually don’t hear many string theorists making this argument these days. If the theory actually were beautiful in the sense of providing some impressive new understanding of physics in terms of some simple, compelling mathematical or physical idea, that actually would be a good reason for believing in it, although not a completely conclusive one. All attempts so far to connect the theory to real physics lead to hideously complicated and ugly constructions. Some string theorists such as Susskind, argue that one should believe in string theory anyway, and it is this argument which seems to me to be more like religion than science. It’s my impression that Susskind and others are believing something for sociological and psychological reasons, something for which they have no rational, scientific argument. This behavior is not distinguishable from that of many of the intelligent designers, and if it becomes more widespread it ultimately threatens to do real damage to the public perception of science in general and theoretical physics in particular.
Krauss gets closer to the real difference between string theorists and intelligent designers when he says that string theorists “are trying to come up with predictions that actually do something”. More sensible string theorists are well aware that what they are doing isn’t going to be part of science until they figure out a way to use it to make real predictions that can be tested. In general, given a new speculative idea, it will not be obvious how to figure out all of its implications and see whether it can lead to real predictions. It can take years of work for this to become clear, and this sort of work is definitely science. On the other hand, if after a lot of work, there still is no indication that an idea can produce predictions, the continued pursuit of it at some point stops becoming science and starts becoming something more like religion. Susskind and other anthropic landscapeologists have already gone past this point: they have no plausible idea about how to ever get real predictions out of their framework. String theorists who argue that the theory is still too poorly understood, that more work is needed to understand whether there is some way around the radical non-predictivity implied by the landscape, are nominally still doing science. But at some point, as years pass without any progress in this direction, and evidence mounts that hopes for ways to get predictions aren’t working out, this activity stops being science and it too starts being a non-scientific activity pursued for sociological and psychological reasons. We’re close to that point, if not already past it.
Update: There’s a defense of string theory against the charge that it’s like intelligent design over at Kasper Olsen’s blog. I don’t find it very convincing, since it doesn’t address at all the question of how string theory is ever going to do what a real science is supposed to do: make falsifiable predictions. Much of Olsen’s list actually strikes me as a recitation of a catechism of supposed reasons why string theory is so wonderful, rather than a serious scientific argument. Some of these are also highly dubious (e.g. “the Standard Model can be reproduced in a very simple way”), they’re things that one has to be a true believer to say, since they really don’t accord with reality.
One commenter (Gavin), gave a very good reason for distinguishing string theory from intelligent design: “the former is trying to explain something that is already explained, while string theory is trying to solve a mystery” and he correctly notes that while string theory’s scientific credentials may be weak, the problem is that there aren’t really good alternatives (LQGers may argue with this…). John Baez’s comment about the relationship of math and physics was also quite nice.
I have the feeling that this was not an isolated incidence in the history of mathematics, but that inductive/experimental approaches in mathematics are alive and well.
I would say so. If you have situations in physics such as particle reductionism and you are reaching limits, why would you not say, okay, let’s try something different and quite profound in our general concept makeup. Let’s shake the foundation up?
Did string theory succeed? Did they point to a time where we knew good scietntists were working in conjunction with views on the cosmo?? It further refined our views on how we view the early cosmo? Guth’s was the first three minutes, refinement, meant something else here.
Dan, sorry but you’re engaging in the really obnoxious behavior I’ve experienced time and time again from string theorists. The sentences you quote are not “plain wrong”; they are perfectly accurate. You’re putting your own construction on them which has nothing to do with what I was saying, then using this to attack me as not knowing what I’m talking about, using your anonymity in a cowardly fashion. If you don’t think something I wrote is correct, how about writing in to ask me to elaborate? Then if I don’t know what I’m talking about, my elaboration should make this very clear and you can joyfully point this out. Or you might find out I just meant something different than what you thought.
I can’t be sure, but I assume you’re objecting to my final sentence, which had nothing at all to do with the “physical significance” of the Calabi-Yau in the constructions you’re thinking of. I was referring to the potential significance to a real physical problem: that of getting non-perturbative information about 4-d gauge theories relevant to the standard model. I realize this is kind of strange behavior you may have trouble understanding, but when I use the term “physical”, I’m just about always referring to the physics of the real world. By “physical significance” I meant “significance for physics”, real world physics. In the real world the main reason you want to better understand non-perturbative gauge theory is QCD (a secondary reason is that you might believe in something like technicolor and want to use non-perturbative gauge theory behavior to break electroweak symmetry).
That’s the elaborated version of the last sentence you quoted. If you think that it’s “plain wrong” and evidence I don’t know what I’m talking about, let’s hear why. If your problem was with one of the other sentences, we can go over those too….
playing devil’s advocate here, if there was a house fire, one of two hypothesis as to the origin of explusion may be possible
1- it is of human origin (accident, or intentional)
2- it is the result of natural processes (i.e faulty wiring)
how would we tell apart 1 from 2? could such methods apply to biological organisms?
Dan said:
“A shorter answer: String theorists are sincerely interested in extending known and tested scienceâ€?
String theorists are sincerely interested in extending known and tested science, into unknown and untested science.
“playing devil’s advocate here if there was a house fire, one of two hypothesis …..”
Huh? Should have put this where most biological material coming from a back hole belongs.
Math deals with all possible worlds; physics tries to select the one we live in. Math is Jules Verne; physics is Tolstoi. Intelligent design is situation comedy; string theory is Gertrude Stein turning Joyce”s “Finnegan’s Wake” (without consulting Gell-Man) into an opera (music by John Cage).
Math is not only a language in the way French, English, etc., are languages since I can analyze the structure of languages with mathematics. As Russell (and Frege before him) showed, math is neither mental nor physical — it deals with an objective world (in the sense that the axis of the earth is real but neither mental or physical). Math ideas can start out as generalizations of the particular (Gauss’ technique) or figues and systems created from basic abstract concepts (invariance, symmetry, etc.). The math I do has direct physical applications (temperature profiles of elastic extruder dies; power requirements of a splicer; gear ratios,etc.) but it all has a basis in fundamental concepts.
Next i will write a list with all correct physics has been already obtained from string, brane, and M theory.
– [ ]
– End.
P.S1: Witen Fields medal was not awarded for work in string theory.
The 1990 Medal was for Vladimir DRINFELD, Vaughan F.R. JONES, Shigefumi MORI (University of Kyoto), and Edward WITTEN. None of awards was for work in string theory.
Regarding Witten the award was for “Completed an amazing proof of the classic Morse inequalities and gave a proof of positivity of energy in Einstein’s theory of Gravitation.”
None of them directly based in string theory. In fact a posteriori one can search some link between string theory and part of Field Medals Witten’s work, but the claim that Witten received the Medal for string theory is just an abuse of language, somewhat as “string theory predicts gravity“. Both Newtonian gravity and general relativity were discovered before string theory!
P.S2: The myth says that Ed Witten is the new Newton. This is rather difficult to believe. Newton was a real mathematician with an insight beyond rest mathematicians of his epoque. Witten is more a particle physicist with a very good command of math.
String theory community over-popularizes Witten’s contributions claiming that Witten is doing ‘real’ math and stating that string theory ‘is’ math. This distorted view is neglected by own mathematicians. The correct place of Witten in math is brilliantly explained as [*]:
Although mostly not in the form of completed proofs, Witten’s ideas have triggered major mathematical developments by the force of their vision and their conceptual clarity, his main discoveries soon becoming theorems. His Fields Medal at the 1990 International Congress of Mathematicians acknowledged the growing impact of his work on contemporary mathematics.
Reading above, I understand Witten’s work as a kind of ‘pre-mathematics’. Newton did not “pre-mathematics”, Newton did mathematics. From the mathematical side, string theory is a kind of ‘pre-mathematics’.
[*] ICM-90 Kyoto, Japan, Notices Amer. Math. Soc. 37 (9) (1990), 1209-1216.
Juan R.
Center for CANONICAL |SCIENCE)
FOR IMMEDIATE RELEASE:
http://physicsmathforums.com/showthread.php?p=788#post788
Tied Up & Strung Out: Hollywood String Theory Movie!!! Looking For Extras!!!
ALL TIED UP & STRUNG ALONG, a movie about String Theorists and their expansive theories which extend human ignorance, pomposity, and frailty into higher dimensions, is set to start filming this fall. Jessica Alba, John Cleese, Eugene Levie, Jackie Chan, and David Duchovney of X-files fame have all signed on to the $700 million Hollywood project, which is still cheaper than String Theory itself, and will likely displace less physicists from the academy.
“As contemporary physics is about money, hype, mythology, and chicks,” Ed Witten explained from his offices at the Princeton Institute for Advanced Study, “The next logical step was Hollywood, although I thought Burt Reynolds should play me instead of Eugene Levy.”
Brian Greene, the famous String Theorist who will be played by David “the truth is out there” Duchovney, explained the plot: “String theory’s muddled, contorted theories that lack postulates, laws, and experimentally-verified equations have Einstein spinning so fast in his grave that it creates a black hole. In order to save the world, we String Theorists have to stop reformulating String Theory faster than the speed of light. We are called upon to stop violating the conservation of energy by mining higher dimensions to publish more BS than can accounted for with the Big Bang alone, and I win the Nobel prize for showing that M-Theory is in fact the dark matter it has been searching for.”
Greene continues: “At first my character is reluctant to stop theorizing and start postulating, but when my love interest Jessica Alba is sucked into the black hole, I search my soul and find Paul Davies there, played by John Cleese. I ask him what he’s doing in my soul, and he explains that the answer is contained in the mind of God, which only he is privy too, but for a small fee, some tax and tuition dollars, a couple grants here and there, and an all-expense-paid book tour with stops in Zurich and Honolulu, he can let me in on it. And he shows me God in all her greater glory, as he points out that we can make more money in Hollywood than writing coffee-table books that recycle Einstein, Bohr, Dirac, Feynman, and Wheeler. I am quickly converted, and I agree to turn my back on String Theory’s hoax and save Jessica Alba.”
But it’s not that easy, as standing in Greene’s way is Michio “king of pop-theory-hipster-irony-the-theory-of-everything-or-anything-made-
you-read-this” Kaku, played by Jackie Chan. Kaku beats the crap out of Greene for alomst blowing the “ironic” pretense his salary, benefits, and all-expense paid trips depend on. “WE MUST HOLD BACK THE YOUNG SCIENTISTS WITH OUR NON-THEORIES!! WE MUST FILL THE ACADEMY WITH THE POMO DARK MATTER THAT IS STRING THEORY TO KEEP OUR UNIVERSE FROM FLYING APART, OUR PYRAMID SCHEMES FROM TOPPLING, AND OUR PERPETUAL-MOTION NSF MONEY MACHINE FROM STOPPING!!” Kaku argues as he delivers a flying back-kick, “There can be ony ONE! I WILL be String Theory’s GODFATHER as referenced on my web page!! I have better hair!”
But Greene fights back as he signs his seventeenth book deal to make the hand-waving incoherence of String Theory accessible to the South Park generation, senior citizens, and starving chirldren around the world. “Kaku! Kaku! (pronounced Ka-Kaw! Ka-Kaw! like Owen Wilson did in Bottle Rocket),” Greene shouts. “It is theoretically impossible to build a coffee tables strong enough to support any more coffee-table physics books!!!”
“Time travel is also theoretically impossible, but there’s a helluva lot more money for us in flushing physics down a wormhole. Nobody knows what the #&#%&$ M stands for in M theory ya hand-waving, TV-hogging crank!!! Get it?? Ha Ha Ha! We’re laughing at the public! We’re the insider pomo hipsters! Get with the gangsta-wanksta-pranksta CRANKSTER bling-bling program!!”
How does it all end? Does physics go bankrupt funding theories that have expanded our ignorance from four dimensions into ten, twenty, and thirty dimensions? Do tax payers revolt? Do young physicists overthrow the hand-waving, contortionist bullies and revive physics with a classical renaissance favoring logic, reason, and Truth over meaningless mathematical abstractions? Does Moving Dimensions Theory (MDT) prevail with its simple postulate? We’ll all just have to wait!
But in the meantime, how do you think it will play out?
Will theories with postulates ever be allowed in physics again? Or will the well-funded, tenured pomo String Theory / M-Theory (Maffia-Theory) Priests send their armies of desperate, snarky postdocs and starving graduate students forth to displace and destroy all common sense, logic, reason, and physics in the academy? It must be so–for the greater good of physics, the individual physicist, and thus physics, must be sacrificed.
MDT’s postulate: THE FOURTH DIMENSION IS EXPANDING AT A RATE OF C RELATIVE TO THE THREE SPATIAL DIMENSIONS IN QUANTIZED UNITS OF THE PLANCK LENGTH, GIVING RISE TO TIME AND ALL CLASSICAL, QUANTUM MECHANICAL, AND RELATIVISTIC PHENOMENA.
http://physicsmathforums.com/showthread.php?p=788#post788
Juan R.
That is why I said one if not two Fields medals arose from string theory. Borcherds’ work, according to the blurbs, used methods from string theory.
Juan, I heartly disagree that mathematics has to be reduced to euclidean style theorem proving machinery in order to be labled as maths. But this is an old discussion that can be rooted back into ancient times of old greeks who didn’t accept Archimedes as a mathematician due to his heuristic style argumentation. I do think the distinction between what is mathematics and physics in the work of Witten is small-minded hairsplitting and philistine. It does not have any cognitive value at all and is a science-political one.
By the way I do not understand Peters argument against ST that it will be perpetuated for social and psychological reasons? This is obviously true for the whole endeavour of finding a “theory of everything” that fits well into a certain academic-cultural pattern that promises high payouts of symbolic capital and intellectual influence to those who make any progress. Denying progress and deevaluating the symbolic capital of researchers will naturally force them into defense and closing the lines against attacks – whether the research program gets stuck or not. This is not very special to ST.
That is why I said one if not two Fields medals arose from string theory. Borcherds’ work, according to the blurbs, used methods from string theory.
Borcherds? I thought you meant Kontsevich. Borcherds work belongs properly to 2d chiral conformal field theory. He’s studying a kind of sigma model, but there’s no coupling to worldsheet gravity, and hence no sum over Riemann surfaces. Not very stringy. Kontsevich’s work, on the other hand, does make use of such sums; he’s actually using the CFT to make string theory computations.
Kontsevich’s work on the other hand, does actually involve integrating sigma model correlation functions over the space of conformal structures.
Arun Said:
“Juan R.
That is why I said one if not two Fields medals arose from string theory. Borcherds’ work, according to the blurbs, used methods from string theory.”
I agree that Borcherds’ work is related to ‘string theory’ in some sense, but your suggestion that “Fields medal arose from string theory” is another exageration.
In 1998 the Fields Medal was for
W. Timothy GOWERS, Maxim KONTSEVIC, Curtis T. McMULLEN, and
Richard E. BORCHERDS.
BORCHERDS was explicitely awarded for work in Kac-Moody algebras and automorphic forms.
b = d·h is math
F = m·a is physics
kc, of course, math is an ‘independent’ discipline. My emphasis was on the link math-reality, which cannot be done without physical sciences playing the role of ‘intermediary’. Paraphrasing Feynman, “Euclidean geometry lives in a mathematical word” aplication of Euclidean geometry to real word is an approximation, strictly speaking there is no real object following rules of Euclidean geometry.
Even if string theory was correct (it is not of course). Nothing in the physical word could be identified with a string unnless one used certain methaphysical considerations outside of pure physics.
Juan R.
Center for CANONICAL |SCIENCE)
Juan,
I know nothing of the math. involved; I’m merely quoting from things like this, from a mathematical org. website:
http://www.icm2002.org.cn/general/prize/medal/1998.htm
” In his proof, Borcherds uses many ideas of string theory – a surprisingly fruitful way a making theoretical physics useful for mathematical theory.”
Borcherds was awarded the medal for proving the “moonshine conjecture” which has something to do with the monster group.
Is that Kac-Moody & automorphic forms? I have no idea.
Of general interest, here is Faddeev on Witten:
http://www.mathunion.org/General/Prizes/Fields/1990/Witten/page1.html
Witten is cited for several contributions, of which item 3.
“Rigidity Theorems” is from string theory.
http://arxiv.org/abs/math/9808136
Arun,
All the work you’re citing is 2d QFT, not string theory. I think AJ is right to point out that you’re only really doing string theory when you integrate over the space of metrics on your surface (and sum over genera). If you’re doing 2d QFT on a riemann surface with a fixed metric, that’s just QFT, not string theory.
Witten’s rigidity theorems come from looking at a supersymmetric 2d QFT on a torus. Borcherd’s vertex algebras are basically an algebraic version of conformal field theory. Again, these are 2d QFTs, and he’s not summing over the 2d metric or genus. It’s certainly true that a lot of work on 2d QFTs has been motivated by hopes it will be useful in string theory (especially in the case of conformal field theory), but the things you’re quoting are purely QFT results.
There would be some beauty if say it was obvious that all of physics came from something like Fibonacci numbers. Then you could say perhaps physics was coming from the most natural math. Fibbonacci numbers come from Clifford Algebra and CLifford Algebra may be the most natural math for physics, spiritual geometry, personality models, etc. The crack in the door that lets ugly things like SUSY in is that no matter what theory is right, there probably is some ugly symmetry breaking somewhere but SUSY seems too ugly. Symmetry breaking is supposed to reduce possibilities while SUSY adds a bunch of not needed possibilities before eventually reducing them.
This beauty issue is a canard. Things like GR and Dirac eqn are beautiful because they are actual solutions to standing problems, not imagined ones, moreover, they don’t have the defect of overstaying their welcome when they are exhausted.
This issue isn’t beauty – it’s metaphysics, philosophy. The entire idea of string theory was obviously false from the first minute, because it was out of context all the way back to Democritus, and because it adopted whole cloth a discredited physical idea, Kaluza-Klein theory, also in disrespect to the tradition that says, when it’s wrong, it’s wrong.
-drl
Dear Peter,
Of course I’ll have to object to your objection 😉 But you should consider the fact, that there is (at least) a 6 hour difference between your continent and mine (so, now it’s around 3.00 AM). I’ll update my comments as soon as possible…
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Regarding platonic mathematics:
The foundation of math is a messy business. Typically one starts by developing a meta theory describing how to prove theorems. Each proposition is viewed just as a typographical string of symbols, which can be manipulated according to so-called rules of inference. You start out with certain strings which you call axioms, and if you can manipulate them according to the rules of inference, eventually reaching some more involved proposition (which is just another string of symbols), you call that new proposition a theorem. The meta theory describes how all this is done. The problem is of course that the meta theory really needs a meta meta theory to be rigorous, and so on ad infinitum. Also, all mathematics, including set theory, has to be formulated with the help of the meta theory, but the meta theory actually assumes some set theory! Namely, it is talking about the set of allowed symbols. So it’s really quite messy if you think about it. In the end, you may even come to the conclusion that mathematics presupposes language, in some sense. Platonism seems to me like just a suspension of whatever doubts and concerns you might have about these kinds of issues (“the mathematical truths are alive and happy in math heaven” ;-)), rather than a real resolution.
Peter,
Thanks for mentioning my earlier comment in your update. The same distinction I made between intelligent design and string theory can also be make between string theory as a theory of particle physics and string theory as a theory of quantum gravity.
String theory as a theory of particle physics is up against very strong competition from quantum field theory. There is nothing from particle physics experiments to suggest that quantum field theory is wrong. There was a hope at that string theory might predict certain features of the particle spectrum and interactions, but that path has not emerged.
However, string theory as a theory of quantum gravity is quite another story. There is no established theory of quantum gravity to unseat; the field is wide open. LQG is in the running, perhaps other ideas offer promise as well, but none of the theories are the “evolution” of quantum gravity. They are all speculative and untested.
This brings me to my concern about the “not even wrong” criticism of string theory, which is that it will apply to any theory of quantum gravity. Short of a complete miracle (like detectable large extra dimensions), the Planck scale is going to be out of experimental reach for a very, very long time. Maybe LQG has better prospects that string theory, but it is probably too young to tell. Even if there are certain regions of parameter space where quantum gravity theories offer low energy predictions, there will also be large regions of parameter space with nothing but QFT at attainable energies. If experiments fails to produce direct evidence for any of these theories, they will all be able to retreat to high energies and avoid falsifiability.
So my question, Peter, is should we be thinking about quantum gravity at all? Since no theory is going to be falsifiable, should we just call the whole thing off? If looking for a theory of quantum gravity is something that we should be doing, then certainly string theory is part of the program.
I’m concerned that the attack on string theory as unscientific is going to taint the entire pursuit of quantum gravity, a pursuit that I think is worth while. String theory is not a strong competitor for a theory of particle physics, but bad player in the major leagues can be a great player in the minors. We should make sure the player is in the right league, not kick him out of the sport. String theorists certainly have confused this issue as well. Having taken the lead in quantum gravity, we act like string theory is up 3-0 in the world series of physics.
I hope that we can turn the debate away from the unproductive question about whether string theory is star or a failure and toward a consensus about where string theory belongs.
Gavin
Peter:
Whatever. I don’t have a stake in this either way. If Faddeev and Atiyah say that Witten derived something from string theory in their talk felicitating Witten on his Fields Medal, and AJ and you say its not string theory; or the Mathematical Congress puts out a press release saying that Borcherds used methods from string theory (the press release also says that string theory is controversial among physicists, so they weren’t trying to get on a bandwagon) and here folks say nay, then I’ll leave it for the historians of science to figure out who is correct.
Perhaps the mathematicians have a different understanding from physicists of what string theory is, and maybe it is the wideness and imprecision about what string theory is that is contributing to our collective irritation with it.
BTW, while I don’t have a stake in the discussion, I do appreciate it. How else would I learn the fascinating fact (Borcherds, 1992) that “The monster Lie algebra is the simplest example of a Lie algebra of physical states of a chiral string on some orbifold.”
Hi Arun,
Lots of people claim that 2d conformal quantum field theory results are string theory results, and this is one of the main reasons mathematicians are so impressed by string theory. Personally I think this completely muddies important issues, and that people should be careful to keep straight what is really string theory and what isn’t. Others undoubtedly disagree.
Gavin
String theory NEVER was a valid theory of particle physics. Never wad a real competition! Physical states in string theory are supersimmetric masless states. There is not such one thing is the standard model of particles.
Of course, all current models of QG are speculative because experimental QG does not exist still. However, string theory is not comparable to rest of alternatives. In general, the rest of alternative rely on ‘direct’ modifications of the already known. String theory is based in an unending introduction of speculations and unobserved things; with each new failure -since 40 years ago, experimental disproval, etc, string theorists introduce some new unobserved thing claimed to be fundamental.
Moreover it is not clear that any quantum gravity theory cannot be falsifiable. Remember that the scale of the string in string theory is introduced by hand and choosed to be the Planck scale. Perhaps some QG effect can be detected at usual but high energies in other formulations or perhaps QG was UNOBSERVED. In fact, this was the point of Dyson some time ago. He argued that gravitons may be unobservable and therefore any QG are outside of physics.
Is he right? I still unknow.
People does not attack string theory ‘as unscientific’. In fact, this is the reason that other approaches to QG are NOT usually atacked. That people attacks is the arrogance of string theorists and premature -wrong- claims by guys like Kaku, Greene, Witten, Schwartz, etc.
People attack heavy marketing for public, loop theoreticians attack when string theorists claim in public that string theory is the ONLY approach to quantum gravity. Honest physicists attack books as “The Elegant universe” by Greene, Profesors attack the attempt to giving courses on string theory to students of physics, etc.
People attack the lack of honesty of many string theorists, who popularize string theory hidding all of its flaws. In fact, in personal communications and talks string theorists agree that string theory is not now a theory of strings -in M theory the D0 brane appears to be fundamental- but public still beoieve thst string theory claim that universe is done of small vibrating strings.
If you ask to string theorists why the name string theory is maintained in popular books and magazines they reply “because marketing purposes“.
Juan R.
Center for CANONICAL |SCIENCE)
‘If you ask to string theorists why the name string theory is maintained in popular books and magazines they reply “because marketing purposes“.’ – Juan R.
I sadly agree. Marketing is now deemed to be the problem of adapting a product to fit the customer.
Without wanting to be harsh on anyone, some philosophical input may be timely.
AG writes:
It is notoriously difficult to draw the Popperian demarcation line, but surely there is a fundamental difference between string theory and intelligent design. When embarking on a scientific research program, it is not always possible to tell from the start what falsifiable predictions or practical applications might emerge, and theoretical scientists have to go on well-formulated hunches and search for ways to corroborate their hypotheses; nonetheless, their efforts can still be called science. Intelligent design, however, is not science– not because it cannot be falsified, but because it cannot, even in principle, be corroborated either. How can an ID proponent move forward with his “research program�?
For Popper, corroboration is the survival of an attempt to falsify, so you cannot have the possibility of one without the other. Popper doesn’t develop a notion of positive evidence until his later rather ugly theory of verisimilitude. This is what marked Popper off from the logical empiricists who saw the need for a logic of confirmation. But AG is using the language of someone you generally teach after Popper, namely Imre Lakatos. The last sentence I quoted is thoroughly lakatosian. A program has a heuristic spirit. It isn’t fully worked out. If it encounters problems, it needs to have the resources to move in progressive direction. It mustn’t make ad hoc moves by, say, artificial exclusions of events from falling under a law, or unnatural borrowings from rival programs.
Lakatos is also interesting for adapting and welding ideas from Popper and the mathematician George Polya (with a sprinkling of Hegel). Polya had developed a probabilistic (Bayesian, without using the word) logic of confirmation for mathematics. Lakatos takes on a case suggested by Polya, the V-E+F=2 formula for polyhedra, and argues that mathematics is ‘quasi-empirical’. He would disagree with:
Subhash wrote:
Has it been falsified, or not falsified, in mathematics, the statement that two parallel lines shall never cross? You’ve got to know neither case is right or wrong.
There is no empirical truth in mathematics. All math are logical derivations from a few fundamental rules which we probably took for granted, but which do not need to be taken for granted as truth, like the parallel line hypothesis. As such, all you could ever say is certain statement is either consistent, or inconsistent, with the set of hypothesises that your math is based on. There is no absolute truth.
Lakatos’s idea was that Polya had been right to find a strong parallel between mathematical and scientific activity, but had erred in thinking that what was common was probability-based inductive reasoning. Instead, Lakatos suggests that what’s common is a passage from certain observed facts to an explanatory framework for them, driven by the proposal of theories and the provision of counter-examples. The important point is that the language changes through this process. In the case of the Euler conjecture, the term ‘polyhedron’ is transformed from an imprecise, intuitive term to a mathematical definition. This courts the danger that something of the original intuitively understood domain may fail to be captured. About Subhash’s mention of parallel lines, a Lakatosian story would tell the history of mathematical conceptions of space. If progressive, we’re achieving an ever less partial understanding of space. This is clearly unfinished business. Read the second half of Pierre Cartier’s great article ‘ A Mad Day’s Work’. Any comments about my own attempt to move beyond Lakatos, explained in a paper ‘How Mathematicians May Fail to be Fully Rational’ (link form my webpage), would be welcome.
Peter wrote
My own inclinations are kind of hyper-Platonist, thinking that ultimately we will see that the deepest mathematical structures and the deepest physical structures are very closely related.
The closest to a modern philosophical account of this is Roland Omnes’ ‘Converging Realities’. Omnes (a physicist) calls it physism.
David
David – I’ve read some of Lakatos’ views which I quote on my webpage, namely his essay in a 1974 Open University book “Philosophy in the Open”. He is critical of Popperian critical experiments and of Kuhnian revolutions because both always “turn out to be myths” caused by historical revisionism. Thus, caloric, phlogiston, and ether died out as their proponents died, not in a blinding flash of revelation when people like Priestley did experiments. Still today the FitzGerald 1889 interpretation of the Michelson-Morley experiment is heresy and cannot be discussed because it is actively defended by a group of crackpot dissenters.
While I respect Lakatos for pointing out that Popper’s and Kuhn’s views are total nonsense, I fear he is simplistic himself in claiming that revolutions occur when “progressive research programmes [British spelling – sorry] replace degenerating ones”. In the case of string theory, which ultimately stems to Kaluza 1919, the whole speculative endeavour has been sustained by propaganda and make-believe, and people have done very well out of it. Is this progressive or degenerative? A-level uptake of physics and maths is falling off in the UK, but that just leads to demands for more “popularisation of string theory” to make the subjects more appealing. With no real rival, string theory will run physical science and maths into the ground, without “degenerating” in the despondent way Lakatos imagines.
Therefore, string theory need never collapse. When Peter’s book “Not Even Wrong” appears next March, will ST collapse? No! Basically, Peter is doing the ST lobby a favour by pointing out to them areas which need to be dressed up more effectively, or worked on harder. His own ideas like http://www.arxiv.org/abs/physics/0102051 have not caused much impact yet: he says a good way to advance the standard model is SO(4) spinors and Clifford algebras, and analysing path-integrals. When you dig into the complexity of this, it is as technical as string theory but is in the opposite direction. It is also more realistic, and therefore further from science fiction of parallel universes and M-theory.
Is string theory going to shut up shop next March when his book “Not Even Wrong” comes out? I doubt it. Personally, I’m impatient with string theory. Not because I don’t like 6 dimensional manifolds or vibrating strings, but because they are not building on what is known. If it turns out there is some evidence for any of this, OK, it would deserve some allocation of research. But it is just crackpotism, and then these people dismiss others who are struggling without any grants in bad conditions as being “crackpots”. They have no shame but too much egotism.
Whoops, the Woit ref I meant was http://www.arxiv.org/abs/hep-th/0206135 ‘Quantum Field Theory and Representation Theory: A Sketch’.
Arun: Go read Borcherd’s original paper. http://math.berkeley.edu/~reb/papers/monster/monster.pdf
He does say string theory in several places: He’s studying a vertex algebra which describes the chiral states of a sigma model to an orbifold, and he’s using a no-ghost theorem that was originally proved by string theorists who wanted to think of the sigma model’s Fock space as the space of single string states for some string theory.
But Borcherds is not making any essential use of the string theory picture. He never needs to think of the string as interacting. So saying his result is inspired by string theory is true in a sociological sense, and it’s also true in a rather weak technical sense: It’s like saying a result in relativistic quantum mechanics is a result in quantum field theory.
I’m about done with this topic.
In the case of string theory, which ultimately stems to Kaluza 1919, the whole speculative endeavour has been sustained by propaganda and make-believe, and people have done very well out of it. Is this progressive or degenerative?
In case of ST it resided a niche i.e. it did not have strong competitors to subdue. Lubos insistence in ST to be the only attempt of a unified theory reflects this ( of course he is well aware about LQG but asserting that it is not a competitor is part of the same rhetoric ). From Poppers analysis we can conclude that ST will wiped out only in presence of a better approach ( simpler, more concise, fruitfull and falsifiable ). From Lakatos we can conclude that history will be written and re-written by the victors who present a rational reconstruction ( rationalisation of their victory ).
Peter et al describe the crisis of ST, it’s inability to return to the real. But in absence of a valid theory it might be the only possibility to survive in theoretical physics – as abstract art. Some find it beautifull.
Arun, AJ, Peter:
The physically successful application of 2D CFT is in the theory of 2D phase transitions. This is part of condensed matter physics and has nothing to do with strings as a theory of quantum gravity. It is true that this discovery was made mainly by string theorists, who happened to have access to the relevant mathematical machinery.
However, string theory is not a ToE even in statistical physics – it says everything worth knowing about 2D phase transition but nothing about the physically more relevant 3D case. In fact, this was my original motivation for generalizing stringy mathematics to higher dimensions, which led to my discovery of multi-dimensional Virasoro algebra and its representation theory.
Gavin:
Whereas string theory is not a successful theory of quantum gravity in 4D, there is no doubt that the worldsheet theory of the free string correctly describes gravity coupled to scalar fields in 2D. The most striking thing from this viewpoint is that gauge components of the metric becomes physical after quantization. This manifests itself in different ways: the Hilbert space in lightcone quantization cannot be reduced due to the conformal anomaly, or one must explicitly keep the trace of the metric (the Liouville mode) as a dynamical field.
Analogously, one may expect that the metric field in 4D has more components after quantization than the two transverse graviton polarizations, due to diffeomorphism anomalies. This was another motivation for my generalization of stringy math beyond two (or rather one complex) dimension.
Nigel,
Your points are well taken. I think we must remember that Kuhn and Lakatos were in the business of describing historical cases of one paradigm/programme (I’m British too) superseding another, events seen as rational with hindsight. Leaving aside the point that Lakatos’s own rationally-reconstructed ‘histories’ are often very far from historical reality, of the two Lakatos was more interested in isolating the rational component of the decision, and at one point he hoped that this could help with decision-making in current science, but by the end of his career he’d given up on the idea that conditions could be given which would rationally warrant one switiching programme. Instead, he just insisted that any scientist should be honest enough to acknowledge where his programme was on a scale running from degenerate to progressive.
When you say, “While I respect Lakatos for pointing out that Popper’s and Kuhn’s views are total nonsense, I fear he is simplistic himself in claiming that revolutions occur when “progressive research programmes [British spelling – sorry] replace degenerating onesâ€? “, pointing to string theory as a counter-example, he could reply in a number of ways. First, that rational change might need to be judged over lengthier periods of time. Nowhere does he say that progress must occur in a given period. Further, he could agree with you that ST is in a (permanent) degenerate phase. For the latter he would want us to judge how ST is doing according to his 3 criteria of progress: (1) Is it making new predicitions?; (2) Are these being confirmed, or can it explain already observed phenomena for which ST was not designed to explain; (3) when it encounters problems, does it engage in problem shifts leading to theoretical devleopment in the spirit of the programme.
I guess you’d argue that ST was not progressive according to these criteria. You might also same the same about other candidates for QG. I don’t recall Lakatos suggesting what one should do in terms of institutional support in this situation. Presumably there are approaches which haven’t been given enough support to reveal their potential. All he suggest is honest score-keeping.
I think there are problems with Lakatos, as I outline in the paper I mentioned. There I looked at the ideas of Alasdair MacIntyre. He would suggest that given an acknowledgement of weakness/resourcelessness of their own programme, some of its members should be encouraged to go and learn the languages of other programmes, as second first langauages, to see if they have the resources to understand these weaknesses. Perhaps this is one small piece of advice we philosophers can pass on.
David
David,
Thank you for this detailed reply. I saw a couple of weeks ago a piece in New Scientist by Appleyard, where the historical revisionism in science was blamed for Marxism and Nazism, because Marx used a cranky scientific analysis of history to defend his ideas, while Mein Kampf utilised crackpot genetic theory. It seems absurd that science is to blame for Hitler and Stalin via crackpot official science. I’d better not push my luck here by mentioning the ST propaganda book “Warped Passages”… perhaps that will be used to justify future warped ideas.
What I’m curious about is what Peter intends doing to sort out physics. He says SO(4) can link with U(2) to produce the generations of leptons, etc., in the Standard Model. How far can this approach go toward replacing ST research?
Gavin,
Thanks for another interesting comment. My own view on quantum gravity research is that it is worth doing, but needs to be done differently than most of the rest of physics, precisely because there is now no experimental data, together with the real possibility that there won’t be any in this or even the next century.
Without experimental data to keep a field honest, research needs to be conducted more like in mathematics, with an emphasis on being completely precise and clear about what you have and what you don’t have. If you have experimental results, you can afford to string together (that was an unintentional pun…) a bunch of not very solid arguments and see what you get. If you get something that agrees with experiment, you’re on the right track, if not you try something else. I personally don’t see the point of stringing together a lot of dubious arguments, and at the end claiming you’ve reached the holy grail of a quantum theory of gravity.
So, I think pure quantum gravity research is legitimate, but it really needs to be done with a higher standard of precise thinking than is usual. There’s also a very serious danger that in the end one will discover that one has found an infinite array of different “quantum gravities”, and, without any experimental way of telling them apart, the whole thing becomes not that interesting.
To me the “holy grail” of quantum gravity is not finding a consistent quantization of the classical theory, but finding some sort of useful relation between the (pseudo)-Riemannian geometrical degrees of freedom of GR and the geometrical degrees of freedom (gauge fields, spinors) of the standard model. If one could do that, one might be able to even make predictions about particle physics, in which case whether or not one had a rigorously consistent way of “quantizing gravity” wouldn’t be the most important thing.
Put differently, I think the real problem is how to unify GR and the standard model, not so much how to unify GR and the general principles of quantum mechanics. Of course the latter may be a good thing to think about to get an idea about the former.
“String theorists are sincerely interested in extending known and tested science. Intelligent design “theoristsâ€? are interested in undermining the public’s faith in known and tested science.”
This is false. While you can find SOME fundamentalists who say things like that, it is not true of people like Tipler & Barrow, or Fred Hoyle (his book “The Intelligent Universe” (1986). Remember Hoyle predicted a nuclear resonance (I think in Carbon) using WAP. So WAP is falsifiable. WAP of course is not enough for ID. I don’t mean to suggest that.
Woit,
I completely agree with you that in absence of experimental data, research would be more careful and far from the media popularization until solid results are achieved. In fact, this was more the program of rest of quantum gravity researchers -except exceptions-. due to marketing and popular presure loop theoreticians began to popularize his own views.
It was a true scandal that a string theorist began one talk or a article on a popular magazine with the typical “string theory is the only approach to quantum gravity…”
But the question is: is quantum gravity testable?
Nobody know the reply still. A priory one may wait relevant phenomena at Planck scales, but this is not clear.
It is posible that in some configuration very small effect can cause a big measurable effect. I sincerely think that particle physicists continue thinking in the old ‘linear’ manner:
small cause ==> small effect
which is not true.
The best example are PV effects. ALL particle physicists -including important ones as Weinberg- claimed in the past that parity violating effects were so small that would be unimportant for all chemistry purposes.
Yes, they are very small, but chemistry is mainly a nonlinear discipline and some molecular configurations amplify those initial ultraweak effects even at level of being measured by us. Particle physicists were wrong and electroweak quantum chemistry has arised as a proper discipline.
Sincerely, i wait some kind of ‘nonlinear’ phenomena doing posible some quantum gravity effect visible at available high energies. Of course, i have not proven this still.
About your own insight on the “holy grail� i think that you are in the wrong way.
1) By definition, quantum gravity is a quantization of classical gravity.
2) The Riemannian geometrization of GR is NOT fundamental (in fact, the Cartan extension proves that a pure Riemann geometry is not suficient and teleparallel gravity thought us that the traditional GR spacetime curvature view is a mere ‘mathematical’ artifact)
3) Far from current claims about success of the standard model i would solicit a bit of caution about the correctness of the model. In fact, recent published research in EM suggest existence of experimental data cannot be explained via traditional EM theory. Some recent research in this topic -e.g. Weber electrodynamics or mixed approaches- suggest that QED is NOT correct.
Recent research by Hoyle/Narlikar theory suggests that standard model is not completely correct. For instance, one of most fascinating outcomes of Hoyle/Narlikar theory is that the photon does not really exist, and, however, Hoyle/Narlikar EM reproduces all experimental effects of traditional QED and BEYOND. It appears that some extensions also explain recent experimental data on longitudinal EM forces, Marinov motor, railguns explosions, and some other experimental data -it is posible that some discrepancies on tokamaks reactors was also due to failure of usual EM, QED, and QCD theory (there is some relevant literature on this also published)-.
It has been also published some recent discrepancies of QED in chemistry [Radiation Physics and Chemistry 71 (2004) 611–617]
However, this may also suggest that the current
perturbative expansion is showing some limitations, or
that the renormalisation approach needs reinvestigation.
Of course, it is also possible that the approach of QED
has some particular flaws or limitations which experiment
might be beginning to illuminate.
4) It is not still clear that GR was the correct approach to gravitation even at the classical level. Many of GR tests are also passed by rival theories (e.g. FTG). And as emphasized by David Gross in one of his recent talks,
http://qd.typepad.com/24/2005/01/the_future_of_p.html
“does GR work for strong fields?”
5) The main problem of formulation of a quantum theory of gravity is that GR is clearly incompatible with QM. Therefore a direct -consistent- unification with the standard model is NOT possible. In fact, there is a large history in ‘direct unification attempts’ begining from Kaluza-Klein that you may know better than my. so far i know all direct atemps were abandoned.
Juan R.
Center for CANONICAL |SCIENCE)
Does string theory have any postulates or laws?
Perturbative string theory does. The postulate is that the S-matrix is computed by summing correlation functions obtained from any one 2-dimensional superconformal field theory of central charge c=15 over genera (in a way that follows from a 2D gravity point of view).
The study of this postulate has shown that it has precisely all features expected of the perturbative expansion of a nonperturbatively defined theory. The totality of the latter is still unknown, though the existence of several hints of properties of this theory has made people come up with the working title ‘M-theory’ for it.
Urs, just because you have postulates or laws does not mean you have science. Moses wrote down postulates and laws from God, but that was intelligent design, not science. Your belief in ST is irrational and pseudoscientific. Who told you 11 dimensional M-theory is the best way forward? Some authority figure I suppose?!
I don’t believe in anything. I just answered Ranger’s question. (Which for some reason appears below my reply.)
Sorry about that, WordPress is too stupid to keep track of Daylight savings time. My fixing this around noon today messed up the order of comments a bit.
Peter,
I agree that many theorists have a “if you don’t believe me, just do the experiment” attitude that is not appropriate in a field where experiments are not on the horizon. Can you point me to some quantum gravity research that does not suffer from this illness?
I’m also intrigued about the idea of “finding some sort of useful relation between the (pseudo)-Riemannian geometrical degrees of freedom of GR and the geometrical degrees of freedom of the standard model.” However, I’m not quite sure what that means. Can you point me to any work being done in this area?
I am curious about these things because I am looking for a research direction myself. I earned my Ph.D. in 1999 and spent the next several years as at-home dad while my wife launched her career as a doctor (a path that seemed more practical than string-theorist). My son is in school now, so this summer I went to Strings05 and a couple weeks ago I was at Stanford (my alma mater) learning about what they are doing there. I learned that in six years away from the field, I didn’t miss much.
Bad as things are for string theory, it is hard to see much else in the quantum gravity race that looks better. People wanting experimental results are hoping for a miracle. People who want rigor can’t prove that Yang-Mills exists. People who want simplicity have to wave their hands just to find flat space. Quantum gravity is an exciting problem, but I can’t find a strong horse to put my money on. If I shouldn’t bet on string theory, then I should probably walk away from the race.
Gavin
Gavin,
The kind of thing I had in mind as quantum gravity pursued with an insistence on precise formulations is a lot of the things I’ve seen coming out of LQG, some of which are really rigorous mathematics. For a random example look at some of the papers of Thomas Thiemann.
I said I think the problem of relating the geometry of GR and the standard model is the big problem, I didn’t say I have any good ideas about this… One I wrote about long ago involved trying to understand the electroweak U(2) as a subgroup of the Euclideanized Lorentz group. Some day I’ll get around to working on this idea again and trying to come up with a more sensible version of it.
To my mind there is no really strong horse to put one’s money on in the field of quantum gravity. More interesting things seem to be happening in LQG than in string theory these days and the subject is being pursued in a much healthier way than string theory, so if you want to do quantum gravity, LQG seems to be a more promising direction. There’s also no strong horse for the other huge problem: electroweak symmetry breaking. There at least, maybe in 2008 they’ll be new experimental results, but if one wants to think about this during the next few years, you have to be willing to deal with the situation that there aren’t any good ideas around.
Urs Schreiber, perturbative string theory is ill defined and is incompatible with GR.
The scattering processes do not correspond to anything known of our world, AND, in complex disciplines like chemistry, the trivial S-matrix theory does not work. See
PRA 1996, 53(6) 4075-4103
Of course, ST S-matrix is not exactly equal to QFT S-matrix but above reference continues to hold.
As would i explain that string theory is both wrong and outdated?
Juan R.
Center for CANONICAL |SCIENCE)
Juan
Once you said that physicists were guilty of grossly underestimating the sophistication of chemists, and others, in their attempts to advance their understanding. Are you not being rather hypocritical?
Peter,
The recent papers by Thiemann are too focused to be accessible to me at this point. However, they do point to a couple recent reviews, “Background independent quantum gravity: a status report,” by Ashtekar and Lewandowski and “An invitation to loop quantum gravity” by Smolin. I also found a recent critical review, “Loop quantum gravity: an outside view” by Nicolai, Peeters, and Zamaklar. I hope that these in combination will be a fair introduction to the subject.
Your last post brings us back to the original topic of this thread. We agree that “there is no really strong horse…in the field of quantum gravity.” Therefore, it seems very premature to declare any of the contenders “moribund.” None the less, your informed and well reasoned assessment of the quantum gravity field has been extremely helpful to me. I wish that all of the discussion of this challenging topic could be carried out with the civility I found here.
Gavin
Kea,
Nature is multidisplinar. If you want understand nature you cannot do only physiucs. This is the reason of existence of Institutes as Santa Fe of Center like our.
It is not the paper in Physical Review A i cited in Woit weblog an elegant example of how ideas from chemistry -Prigogine group- have been applied to a generalization of QFT?
Remember P.W. Anderson’s words in his famous Science article:
Biology is not applied chemistry.
Chemistry is not applied physics.
Juan R.
Center for CANONICAL |SCIENCE)
Peter, I think that the question “Why is string theory science but intelligent design isn’t?�
is unfairly disparaging to “intelligent design”.
I am NOT an advocate of or apologist for “intelligent design”, but I note that “intelligent design” seems to be something that certain groups have adopted to replace “creationism” because they found it hard to defend “creationism”.
In my opinion, the current landscape/anthropic/superstring theory is actually very similar to the “creationism” that has been abandoned even by the “intelligent design” people.
I use as a definition of “creationism” the doctrine that the world and everything was created in 4004 BC with all the fossils, stars, ratios of radioactive elements, etc being carefully set up by G-d to produce exactly what we observe today.
The “landscape” of possible superstring models
corresponds to
the set of all possible states of the world and everything as of 4004 BC.
The anthropic principle that selects “our world” out of all the possible “landscapes”
corresponds to
the divine creation by G-d that selected/constructed “our world” instead of any other of all the possible states of the world and everything as of 4004 BC.
Both are quite vacuous in that they say no more than that our world is as it is because it is as it is.
The landscape/anthropic/superstring stuff and the divine creation stuff both exactly describe “our world”, and each is equally useful (i.e., totally useless) in making predictions (or even interesting postdictions) of particle physics data.
However,
since “intelligent design” implies some use of some intelligence by G-d or something
and
since no substantial intelligence whatsoever is required for landscape/anthropic/superstring stuff or “creationism” stuff,
I think that “intelligent design” is far superior to both landscape/anthropic/superstring stuff and “creationism” stuff.
Even so, for the record lest I be misunderstood, I should reiterate that I am NOT an advocate of or apologist for “intelligent design”.
In other words,
I am not saying the “intelligent design” is good.
I AM saying that BOTH landscape/anthropic/superstring and “creationism” are EVEN WORSE.
Tony Smith
http://www.valdostamuseum.org/hamsmith/
Are postulates allowed in modern theoretical physics?
It seems that string theory has no postulates.
Correct me if I’m wrong but it seems that these are the rules of contemporary theoretical physics:
1) postulates are not allowed
2) experimental evidence is not necessary
3) only theoretical research programs that disallow posulates and experimental tests are allowed, as said research programs are best suited to greasing the perpetual-motion NSF money machine.
With no hope of proof one way or the other, and with nothing to prove in the first place, string theory is firmly ensconced as the anti-theory.
I hope I’m wrong, but this seems to be the case.
Please name a postulate or law of string theory.
Or just give me an equation.
Newton, Einstein, and Faraday all gave us postualtes, laws, and equations, and their physics received a helluva lot less funding than string theory.
so what’s going on here?
Hi Ranger,
I have lots of equations for you! Highly non-linear! Fun for years! Gravity, charge, and light!
-drl