There’s almost too much to keep track of the last couple days on the string theory controversy front:
Burton Richter of SLAC has a Reference Frame piece in the latest Physics Today entitled Theory in particle physics: Theological speculation versus practical knowledge. Richter shares my point of view that the Landscape studies currently popular in string theory are not science:
To me, some of what passes for the most advanced theory in particle physics these days is not really science. When I found myself on a panel recently with three distinguished theorists, I could not resist the opportunity to discuss what I see as major problems in the philosophy behind theory, which seems to have gone off into a kind of metaphysical wonderland. Simply put, much of what currently passes as the most advanced theory looks to be more theological speculation, the development of models with no testable consequences, than it is the development of practical knowledge, the development of models with testable and falsifiable consequences (Karl Popper’s definition of science)…
The anthropic principle is an observation, not an explanation… I have a very hard time accepting the fact that some of our distinguished theorists do not understand the difference between observation and explanation, but it seems to be so…
What we have is a large number of very good people trying to make something more than philosophy out of string theory. Some, perhaps most, of the attempts do not contribute even if they are formally correct.
The issue of Nature that just came out today has an article about the controversy by Geoff Brumfiel with the title Theorists snap over string pieces: Books spark war of words in physics. He describes Lubos Motl’s reviews of the Smolin book and mine on the Amazon web-site, and quotes Polchinski and Susskind. The reaction of string theorists to the books is said to be:
Few in the community are, at least publicly, as vitriolic as Motl. But many are angry and struggling to deal with the criticism. “Most of my friends are quietly upset,” says Leonard Susskind, a string theorist at Stanford University in California.
and
The books leave string theorists such as Susskind wondering how to approach such strong public criticism. “I don’t know if the right thing is to worry about the public image or keep quiet,” he says. He fears the argument may “fuel the discrediting of scientific expertise”.
Susskind will be giving a public lecture October 17 at UC Davis on String Theory, Physics and the “Megaverse”.
Polchinski avoids the problems associated with the failure of string theory as a unified theory, and promotes in a somewhat overhyped way the idea that string theory explains the RHIC data.
Finally, Smolin makes an offer to string theorists that I feel I should try and match, hoping they will read his book to better understand exactly what he has to say:
If they don’t want to buy it, tell them to get in touch with me and I’ll send them a copy.
One thing Brumfiel gets a bit wrong is that my problem with string theory is not quite what he says “a fear that the field is becoming too abstract and is focusing on aesthetics rather than reality.” The problems I see are rather different, with mathematical abstraction one of the few tools still available to theorists trying to make progress.
The same issue of nature contains an editorial Power and Particles lustily repeating much of the standard hype about string theory, noting that there are problems, but ending with:
Critical-mindedness is integral to all scientific endeavour, but the pursuit of string power deserves undaunted encouragement.
The editorialist definitely does not seem to be of the opinion that alternatives also deserve to be encouraged.
Finally, lots of reviews of Lee Smolin’s book:
Unburdened by proof by George Ellis, also in Nature. Ellis takes the opposite point of view from the Nature editorialist, calling for more research on alternatives to string theory.
A loopy view by Michael Duff, in Nature Physics. Duff is extremely hostile to Smolin’s book, sneering at Smolin and claiming that his book will “leave the reader rooting for strings” (funny, but this doesn’t seem to have been its effect on most reviewers…). Duff agrees that there are problems with string theory, but claims that the problems Smolin correctly identifies are exactly the ones that he himself first identified back in 1987. String theorists like Duff seem torn between claiming that criticisms of string theory are crackpot nonsense, and that they themselves made them first. He goes on to furiously attack various straw men, accusing Smolin of “denying that any progress has been made!” (something I don’t think Smolin does at all), and answering the criticism that string theory makes no predictions despite more than twenty years of effort by discussing how theories that did make predictions have sometimes taken a long time to be confirmed (or remain unconfirmed).
The string theorists were scammed! by Peter Shor on Amazon.
The Trouble With Physics by Sean Carroll at Cosmic Variance. If I can find the time, I may write about some of my problems with this review as a comment over there.
Peter,
If the quarter you’re looking for didn’t fall near the streetlamp, looking for it near the streetlamp won’t help. Perhaps the truth about nature lies far outside the circle of light cast by current theory’s streetlamp. Perhaps that truth is stringy, perhaps not, but, as Peirce was wont to say, do not block the way of inquiry. Perhaps the exhaustive investigation of string theories will at least have the merit of revealing where the truth about nature is not.
fooltomery,
I think the exhaustive investigation of string theories has already had the merit or revealing where the truth about nature is not. Now the question is what is to be done to make progress on figuring out where it is.
John Walker, founder of AutoDesk (makers of AutoCAD), has a review of Lee Smolin’s book at: http://www.fourmilab.ch/fourmilog/archives/2006-09/000758.html
Burton’s article was great. Thanks for the link.
When I read the following in “Cranks, Quarks and the Cosmos” by Jeremy Berstein, I thought immediately of how the comment applies to string theory. Bernstein was discussing the errors Schroedinger made in his book “What is Life”:
“What is Life” is proof that a brilliant but wrong idea in science can often have more of an impact than a dull but correct one. (page 63)
As I reread that, I realized that it only partially applies to string theory: String theory is wrong, but is not brilliant. Neither is it science.
Will any of my pro-M theory comments remain undeleted?
To say that String theory is not brilliant is a tall order, mathematically speaking. Personally, I am very, very tired of all this pointless bickering masquerading as intelligent conversation. It should be perfectly obvious that both the broad String formalism and some elements from alternative approaches will prove to be relevant to the eventual picture. Also perfectly obvious is that none of the approaches typically mentioned is correct.
Peculiarly, I had forgotten that Walker also reviewed Peter’s book:
http://www.fourmilab.ch/documents/reading_list/indices/book_502.html
a propos controversy
in the long run I think Vilenkin’s CNS paper, posted today on arxiv, will be important because of opening up the controversy over CNS—-which I think will prove significant as a falsifiable conjecture bearing on the determination of fundamental constants.
http://arxiv.org/abs/hep-th/0610051
On cosmic natural selection
Alexander Vilenkin
4 pages
“The rate of black hole formation can be increased by increasing the value of the cosmological constant. This falsifies Smolin’s conjecture that the values of all constants of nature are adjusted to maximize black hole production.”
Vilenkin goes to considerable lengths to refute the CNS conjecture: his argument involves black holes coming into existence by a “quantum fluctuation” and indeed at one point he invokes SOLAR MASS black holes coming into existence by quantum fluctuation
some heat could develop around Vilenkin’s paper
“If they don’t want to buy it, tell them to get in touch with me and I’ll send them a copy.”
Oh great — I read this just after buying both books.
Kea Says:
To say that String theory is not brilliant is a tall order, mathematically speaking.
–exactly the point! Some great mathematics has been done along the way, but there is no physics coming out!–
It should be perfectly obvious that both the broad String formalism and some elements from alternative approaches will prove to be relevant to the eventual picture.
—It is obvious to me that most of string theory will fall by the wayside. But I guess we won’t know for sure until the eventual picture is revealed—-
hi Peter,
I did read your book, and have some thoughts:
1- I might have expanded as a full-length chapter on the history of extra-dimensions in physics, starting with Kalula-Klein, and how they failed, and what that might mean for string theory
2- I might have expanded as a full-length chapter on the history of GUT theories in physics, such as SU(5) and SO(10), and how they were falsified, and, what’s more, how *conservative* they are, in comparison to string theory, and how given several candidate GUT’s have been falsified, what this means for string inspired unification scenarios.
3- I might have expanded as a full length chapter history of physical theories that were “falsified” or found to be inconsistent, and what this might mean for string theory.
4- Maybe with a co-author (i.e Rovelli, Ashketar, Penrose, etc.,) I would have written a full-length chapter on quantum gravity, and how supergravity failed, and then the status of string theory as a theory of quantum gravity, and how well it succeeds in this claim.
5- Given more treatment on failed predictions of string theory. Go into detail string’s version of particles and the standard model.
6- delete the chapter on string theory and mathematics and bogandov affair. Replace it with the SM and GR as to why they are a physics theory, and string theory, why it is not a physics theory.
7- explain that historically speaking, staying with 4D and observation and experiments have resulted in science, as opposed to speculation.
Dan
Garrett,
It’s an offer for string theorists….
Dan,
Thanks, some of the things you suggest are things I would have done if I had the energy and desire to write a longer book. Other things you mention I’m just not that interested in, and in that case think people are better off learning about these things elsewhere (and there are plenty of other places).
I really wanted to write about my own take on the subject, which concentrates not on quantum gravity, but on particle physics, and on the relationships to mathematics.
Luckily for people, there’s Smolin’s book too, which covers a lot of what I didn’t.
For what it’s worth, a reply to Carroll’s review would, at the very least, be appreciated by at least this one reader.
In the mean time, with Richter’s juxtaposition of Thomas Aquinas and the Anthropic Principle, I can’t help but wonder how Weinberg fits with all this…
nontrad,
I hope that Smolin will find time to respond himself to that review, since it’s a more serious criticism than many others. I took the time to write about one part of it, don’t have time for more than that now.
For whatever it’s worth, I’ve only skimmed Smolin’s book in a B&N, but from what I read, I pretty much agree with Sean’s review.
I’d probably end up being a bit more snide, though.
it seems to me that Richter promotes the opposite unreasonable extremism.
First, he omits other successes of naturalness (corrections to the electron mass, to the mass difference between charged and neutral pions, etc). Anyhow, this sort of discussion would have been useful 10 years ago, but is now useless: LHC should soon conclusively tell if the weak scale is natural, or if we lost 30 years on a wrong track.
Second, no experiment tells that the cosmological constant is unnaturally small, because we never probed gravitons at energies above 10^-3 eV. Of course, we all expect that the theory of general relativity can be extrapolated at such “high” energies, giving a naturalness problem.
Third, like it or not, some (but not all) constants of nature really seem fine-tuned for “life”. Since long ago this suggested that a theory that predicts everything does not exist, but it does not suggest that theory should predict nothing; the situation is not necessarily as bad as string theory suggests. For example, LHC data might allow us to reduce the number of free constants by confirming SUSY-GUT.
About RHIC: strings as an approximate model for RHIC is a minor result. One can easily predict that, in the present situation, any attempt of over-over-over-over-hyping it will fail.
reg. the Nature articles see also The inverse problem
When I told my wife that Richter had compared String Theory to Theology, she replied: “What an insult to Theology”.
Peter,
I’m a retired physicist (PhD in quantum optics, 1971) who would love to read the string and quantum gravity literature. While the popular books (including yours) are wonderful reading, they do not help one who wants to follow the calculations.
The research papers are incomprehendable, unnecessarily so in my opinion. Great physicists have found it possible to write advanced research papers that could be followed by a graduate physicist who was not a specialist in the sub-field. That quality is missing in the string and LQG literature.
I believe that could be corrected and wrote an “Open Letter to the Theoretical Physics Community” with a few suggestions on my blog http://palosverdesblog.blogspot.com.
Am I asking for an impossibility?
Keep up the great blogging.
Thanks,
Bill
DAN’S SUGGESTED CHAPTERS
I’d love to read the chapters Dan suggested to add. In particular, I will be happy to have any more detailed but accessible information (or links) on why the high dimensions (26 or 10). Actually, if Dan himself can say more on items 1-3 and 5 on his list and Peter wouldn’t object this will be great!
Some remarks on the controversy:
DO WE REALLY HAVE A CONTROVERSY (YET)?
A striking fact about the debate concerning string theory is that there is almost a complete agreement on factual matters between what string theorists say and what people who attack string theory say. (Can you list some real disagreements?) The interpretation of the facts is sharply different but many of the issues concerning the interpretation are not specific to string theory and are of very general nature.
CAN PHILOSOPHY OF SCIENCE HELP DOING SCIENCE?
This is a fascinating aspect of the discussion here and in Peter and Lee’s books. Philosophers will probably be the most skeptical about such “practical” applications of philosophy, for example, of Popper’s point of view. It is hard to consider various theories in philosophy of science as normative and it is hard to consider them as descriptive. (They also are in conflict, of course.)
These theories can be regarded as a way toward understanding and discussing in a scientific way what science is.
IS STRING THEORY FALSIFIABLE?
Well, I am not sure it is clear what string theory IS. But from the rough description of what it is, it seems very clear that string theory is falsifiable. For example, as Peter explained in the book the 26-dimensional model without supper-symmetry was rejected because it have consequences to physics that are regarded unreasonable. This, in principle, can happen to the super symmetric string theories.
THE BUSINESS OF FALSIFIABILITY
Falsifiability is not just a box you have to check and then forget about but rather it is a major part of the whole endeavor. It is not enough that the theory can be falsified in principle but researchers in the theory should devote considerable amount of efforts in this direction.
DESTROY STRING THEORY AND SAVE PARTICLE PHYSICS?
Peter’s noble reason for his attack on string theory is the desire to save particle physics. Well, one has to be very skeptic about claims of the form “Destroy X to save Y”. In this particular case one can be quite skeptical as well. But, in science, (appropriate) efforts to falsify a theory are as noble as efforts to prove it.
Peter,
Fair enough; re the reply. I’ll look for Smolin’s comments in respective arenas. Thanks for the link none the less.
Aaron B,
With all due respect, I freely admit that I’m one of the worst sorts of skimmers myself, but surely, to review someone’s work requires perhaps more then simply skimming?
All the best,
nontrad
Which is why I didn’t write a review.
HTH!
I’ve been listening to Lee on WGN radio for a while now, and he hasn’t said anything that makes me like him any more, though.
Well, one ought to give both of you guys (Peter and Lee) some serious credit. You forced the issue about the string theory into the open, and since “Nature” noticed it, many other people will take a notice too. That is a remarkable achievement, and not easy by any means! Sociology is not an easier science than physics, influencing masses takes some serious skill. No less than juggling some string equations around 🙂
Is this another episode in the series “Revenge of the Nerds” ? I do not know, but it surely does look so. Oh, the sweet revenge, on the establishement that is always right.
Guys, wow in it, you deserved it 🙂 There is so much political BS in the sciences, at least periodical upset of the status-quo somewhere should remind the establishment that it is not always right.
Signed, “closet revolutionary” 🙂
Controversy is easy. The anti-establishment storyline is an especially easy sell.
And who’s claiming that string theory is right?
Hi Peter,
“Susskind will be giving a public lecture October 17 at UC Davis on String Theory, Physics and the “Megaverse”.”
For some reason, while reading this sentence I could not help smiling, as this reminded me of those kinds of threats faced by people who become the target of fundamentalist muslims, like “we know your address”… As if you were disclosing where Susskind will be talking in order to unleash your adepts against him.
Because this is becoming more and more like a war. A good war – Free Science against String Theory fundamentalists. Should good wars be fought ? Is the risk that one “fuels the discredit of scientific expertise” worth running ?
I think so, but this is a rather odd situation in science, so we have little guidance from the past… The risk exists.
Cheers,
T.
Well, you do not need to look for fundamentalism muslims. Here in Spain, the pubs of RightWind and LeftWind fundamentalists had, pasted in their bulletin boards, this kind of lists of names of addresses of the opposite band.
Hmm, we have Spires anyway.
Tommaso,
I should make clear that encouraging people who disagree with Susskind to attend his talk and in any way bother him was not my intention at all. I mentioned his talk just as an example to show that the pro-Landscape publicity machine is still in action.
These days, the anti-string theory point of view has been getting so much attention that I’m sure much of the audience for his talk will have heard that there are reasons to be skeptical of what he has to say. I don’t think there’s any reason at all for people who disagree with him to go out of their way to attend his talk.
Hi,
I’m en engineer for training and I understand your critisism about string theory. However, to mention one, I’ve read Greene’s book about string theory and I think he’s as honest as anyone could ever be about it. He clearly states that string theory might be wrong, and judging from his interviews I think he’s the most reasonable physicist I’ve ever heard. Same goes for Kaku. Now, I don’t really know if they’re right or wrong. They might very well be wrong. Same goes for Newton and Einstein. Their stuff could very well be only an approximation. What do we really know about the universe? Nothing. We have space telescopes and we can look into the past and make educated guesses about things around us. Now, string theorists have their mathematical models that make sense to them and they make educational guesses based on them. Isn’t that really what science is all about?
Sure, Peter, mine was just a remark to share the funny feeling I had reading your post. But you did well in pointing out you are in no way encouraging people to disagree with Susskind… There indeed is already enough garage fights going on over string theory these days that it is better to state very clearly one is not interested in participating.
Cheers,
T.
BTW the UK edition of Peter’s book was #1 on UK amazon’s physics bestseller list today.
Their physics category is quite broad: their next larger category up
“nature and science”.
I’d say a #1 physics bestseller is worth celebrating.
http://www.amazon.co.uk/gp/bestsellers/books/278409/ref=pd_ts_b_ldr/026-8303087-5718006
At one point today I noticed it’s overall sales rank among all the books they sell was #662 which looks pretty good for a book of this sort.
Here’s to booksales Peter. Cheers!
dear Ari,
Greene forgot to tell that, unlike Einsetin and Newton, string theory seems intrinsically unable of telling anything about physics: whatever you ask, you get 10^500 alternative possible answers.
For example: does string theory predict that we will see supersymmetry?
Answer 1: yes. Answer 2: no. Answer 3: no. Answer 4: yes. etc etc etc 10^500 times.
In practice this can be summarized as: maybe, I don’t know.
There are attempts of getting something out of this bad situation, but so far everything failed. Giving up and starting something else is the common-practice when doing research; but in the case of string theory this process is more difficult, because strings were publicly over-hyped.
Burt’s article was interesting reading… he has been repeating that basic content for some time. Among particle experimenters, he has long been one of the most sympathetic to string theory.
There is a whole generation (maybe even two generations) of particle experimenters who came of age contemporaneously with string theory. Experimenters of all types tend to be skeptics and non-believers, and they are hard to characterize. Generally there is a lot of tolerance for our theoretical friends from grad school, who we often know, and know the talents of, pretty well.
I was turned into skeptic about even SUSY when no new particles were found at PETRA, PEP-I, and the SPPS. That the symmetry breaking scale was near 100 GeV and not a single member of the new particle families was less than that mass seemed (and still seems) suspicious. Of course, we’re not done yet… a neutralino as light as 10 GeV is still a possibility, technically.
Which is a very important point: conclusively ruling out a conjecture as basic as the MSSM is a very strenuous, detailed, and exhausting experimental endeavor. Our theoretical colleagues long ago stopped providing us solidarity in that venture, and the decimation of budgets in HEP is related to our theorists losing interest in the actual physical world. Look at all the cancellations in the accelerator world… KAMI, CKM, KOPIO, RSVP, BTeV, Braidwood (technically a reactor experiment), not to mention a witchhunt over the problems in Run II at the Tevatron. Add the sunset of PEP-II and CESR. On the one hand, many of these experiments don’t seem to be at the energy frontier, and the energy frontier is always the most fruitful. On the other hand, crucial information has come from off the energy frontier… that SUSY generally provides large, flavor-changing neutral currents is a huge problem, and the experiments that failed to see those neutral currents are now over 40 years old, and were not even then performed at the energy frontier.
Let me go back to Burt for a second… there are significant details about him. They concern this oft-repeated statement that experimental particle physics has been in stasis for 30 years… with Burt, remember, that puts his discovery as the last truly significant one on the experimental side (well, maybe, the tau lepton discovery makes the cut too… done by his colleague Martin Perl, although Burt took his name off Perl’s initial paper).
As someone who worked hard in experimental accelerator-based particle physics over those past 30-years, I’d say Burt minimizes the impact of other work (that he did not do) during that 30-year period. Of course he would minimize the impact of others’ work… acknowledging others’ work in those 30 years does not shine his star at all.
Many, many times during those 30 years the Standard Model seemed in jeopardy. Experiments that pursued the apparent shortcomings of the Standard Model during that period were crucial, and IMHO, way, way more important than all of the string theory developed contemporaneously. First, because experiment does provide a measure of empirical certainty, that string theory has not provided (so far). We don’t have to argue any more about whether the Standard Model is mostly right anymore… had the experiments *not* been done, we’d have to constantly add conditions or admit the possibility that the Standard Model might be wrong about heavy quark mixing, low energy parity violation, etc.
Second, many of the experiments done in the last 30 years were the best chance at the time to actually find violations of the Standard Model. Effort was focused where sensitivity seemed apparent to new phenomenon, and actually, the sensitivities so achieved provide very strong constraints on anything new.
Turns out Burt was not very successful at doing most of those experiments. The SLC (his main project) was a fabulous and visionary effort, but was also marred by his organizational shortcomings and tendency to be arrogant.
The SLC got blown away by LEP (and I’m a SLAC alumnus). But now Burt says with some relish that it didn’t matter, since LEP found nothing fundamentally new.
What else happened in those 30 years? I had to think hard to remember all the stuff, because, after all, the bottom line is right that the Standard Model was resoundingly verified. It is easy to just remember that, and forget the tortuous journey we all took. That journey (as I remember it) has a bunch of twists and turns, from excellent and ingenious experiments… I’ll list a few, but I’m sure I overlook many…. the neutral charmed meson lifetime looked very long, but was finally nailed down by a terrific Fermilab experiment… the b-quark lifetime looked an order of magnitude longer than predicted, and turned out to be right… then neutral B mixing turned out to be way larger than predicted, also turned out to be right… these measurements led hard core phenomenologists (not string theorists) to successfully predict a very large top quark mass… the very large top quark mass is probably the central feature of the fermions in the Standard Model, and not a single string theorist predicted it, and indeed, they have reduced the phenomenon to a simple arbitrary parameter… well, then the Tevatron doggedly pursued the top and succeeded due to incredibly dedicated and ingenious work… the top quark discovery dwarfs all of string theory’s contributions (so far) IMHO, and I was not involved in it. Then in CP violation, direct CP violation was an incredible source of controversy throughout the 1980’s and 1990’s, and was finally resolved again through terrific and ingenious experimentation. CP violation in the B meson system turned out to be observable, because of the surprisingly long lifetime and the large mixing, and again fantastic experiments were done on that topic.
Of course, there is the amazing story of neutrino oscillations and mass, that starts in the 1960’s and still has not resolved itself. The major clues were *not* from accelerator based experiments, however, the final decisive experiments *will* be done at accelerator (or reactor) supported facilities.
BTW, is neutrino mass is *not* part of the Standard Model, and
is the first clue of physics beyond it. And many of the key experiments took place during the `30 year hiatus’ that seems to have crept into the string theory apologias.
Of course Burt wants to reduce all that to a wish-sandwich, he was not involved. But the entire experimental community is still there, and knows. They know, they know, and they don’t stand still, and they don’t give up.
A couple of quotes from Sean Carroll’s piece:
“It seems worth emphasizing that the dominance of string theory is absolutely not self-perpetuating. When string theorists apply for grants, they are ultimately judged by program officers at the National Science Foundation or the Department of Energy, the large majority of whom are not string theorists. (I don’t know of any who are, off the top of my head.) And when string theorists apply for faculty jobs, it might very well be other string theorists who decide which are the best candidates, but the job itself must be approved by the rest of the department and by the university administration. String theorists have somehow managed to convince all of these people that their field is worthy of support; I personally take the uncynical view that they have done so through obtaining interesting results.”
and
“To be clear, the scientists working on LQG and other non-stringy approaches to quantum gravity are not crackpots, but honest researchers tackling a very difficult problem. Nevertheless, for the most part they have not managed to convince the rest of the community that their research programs are worthy of substantial support. String theorists are made, not born; they are simply physicists who have decided that this is the best thing to work on right now, and if something better comes along they would likely switch to that. The current situation could easily change. Many string theorists have done interesting work in phenomenology, cosmology, mathematical physics, condensed matter, and even loop quantum gravity. If a latter-day Green and Schwarz were to produce a surprising result that convinced people that some alternative to string theory were more promising, it wouldn’t take long for the newcomer to become dominant. Alternatively, if another decade passes without substantial new progress within string theory, it’s not hard to imagine that people will lose interest and switch to other problems. I would personally bet against this possibility; string theory has proved to be a remarkably fruitful source of surprising new ideas, and there’s no reason to expect that track record to come to a halt.”
I think those are excellent points.
Spear Mark II,
Thanks for the excellent, informative and thought-provoking long comment!
Ari,
Please don’t take up space here putting in long quotes from material I’ve already linked to and encouraged people to look at. You’re not adding anything at all to the discussion.
I responded over at Cosmic Variance to part of Carroll’s piece, for the piece that Ari quoted, there’s an interesting response here:
http://angryphysics.blogspot.com/2006/10/hiring-string-theorists.html
If there’s an interesting discussion going on at other blogs, it would be best if people not try and move it over here, but carry it on at its original location, perhaps providing pointers from here.
Strung along
[Los Angeles Times, Book Review section, Sunday, 8 Oct 2006]
http://www.latimes.com/news/science/la-bk-cole8oct08,1,4278240.story?ctrack=1&cset=true
Not Even Wrong The Failure of String Theory and the Search for Unity in Physical Law Peter Woit Basic Books: 292 pp., $26.95
By K.C. Cole,
K.C. Cole, who teaches science journalism at USC’s Annenberg School, is the author of “The Universe and the Teacup: The Mathematics of Truth and Beauty.”
October 8, 2006
The Trouble With Physics: The Rise of String Theory, the Fall of a Science,and What Comes Next
Lee Smolin
Houghton Mifflin: 392 pp., $26
IN physics, truth and beauty often walk hand in hand. Physicists describe theories as “ugly” or “beautiful,” talk about ideas that “smell” or “feel” right. Often, aesthetic judgments lead to discoveries: as in Einstein’s theory of gravity and Paul A.M. Dirac’s discovery of antimatter. Aesthetics, French physicist Henri Poincaré said, is a “delicate sieve” that sorts the true from the misleading. Or as Dirac famously put it: “It is more important to have beauty in one’s equations than to have them fit experiment.”
To mathematician Peter Woit and physicist Lee Smolin, however, the search for beauty is ruining physics. Their ire is directed at “string theory,” a magnet for physicists because it is so, well, beautiful, and has such great promise for solving what may be the central mystery of the universe — the incompatibility between the two grand laws that describe everything we know.
Quantum theory — which explains the subatomic world with exquisite precision — reveals that at close range, matter, energy and motion are a choppy mosaic of jittery bits. Think pointillist painter Georges Seurat on a triple espresso. Einstein’s theory of gravity, which describes the large-scale cosmos with exquisite precision, tells us that space and time are woven into a smooth, seamless surface that warps under the influence of massive objects — a universe painted by Salvador Dali. Where the two realms meet, the quantum jitters shatter the glassy surface of space-time like a child cannonballing into a pool.
String theory is the first approach that seems to bring the two together naturally, and such unification of opposites, like electricity and magnetism, has driven physics for more than a century. Simply put, string theory does this by replacing point-like particles with tiny strings of some fundamental stuff vibrating in 10-dimensional space — their harmonies creating everything from quarks to galaxies. The loops of string don’t let anything get small enough to let quantum fidgeting rip space and time apart.
String theory has its troubles, which the authors analyze in great and sometimes lucid detail: It appears to be untestable because the strings are too small to be seen, and recent research suggests that the theory may have an infinite number of solutions, so it can’t make predictions. And string theory is so ill-defined that even ardent supporters admit they don’t know what, exactly, it is. This is why Woit calls the theory, and his new book, “not even wrong,” a play on a put-down by the late physicist Wolfgang Pauli.
These issues are well worth addressing, which makes it all the more disappointing that Woit, and Smolin in “The Trouble With Physics,” write mostly about how string theory has ruined their careers — and physics as well. It has “choked off” investigation of “equally promising approaches,” Smolin says. It is a “cult” in which “believers don’t care about evidence.” Physicists who don’t work in string theory are rejected and shunned. “The ability to do mathematically clever work … [is] valued over the possession of original ideas,” he complains. As for beauty, he writes that “elegance” is irrelevant, and “more sober minds” should insist on “a connection to reality.”
Although Smolin’s book is fairer and far more readable, both suffer from an overflow of jargon. And their language is telling: String theory is described as a “fad,” “fashion” or “trend,” its culture as “brash, aggressive, and competitive.” String theorists “swagger.” References to Smolin’s kind of physics, on the contrary, are accompanied by words such as “deep” and “thoughtful.”
Smolin is a respected physicist, having earned a PhD at Harvard University and written several delightful popular books, including “The Life of the Cosmos” and “Three Roads to Quantum Gravity.” He helped found the Perimeter Institute in Waterloo, Canada, as well as a perhaps promising theory called “quantum loop gravity.” He’s also a former string theorist, so his book is well-informed.
Woit is a different story. As a postdoctoral fellow at State University of New York at Stony Brook, he couldn’t find another position because, he says, he wasn’t working on string theory. Woit then moved to Harvard, where the physics department “let me use a desk as an unpaid visitor.” He’s now a math lecturer at Columbia University.
The authors are right to say that physicists can get cliquish; that some of them swagger; that they frequently fool themselves and that science has become too risk-averse. On the other hand, dozens of astrophysicists, cosmologists, relativists and people who study fundamental particles and interactions in ways not related to string theory do quite nicely; some even dip into theory now and then. In fact, many highly esteemed physicists who formerly disdained string theory (Nobel laureates Steven Weinberg and Murray Gell-Mann among them) have become fans.
So it’s hard to believe, as both authors charge, that physicists have been led like sheep to pursue a “failed theory,” mostly by Edward Witten, now at the Institute for Advanced Study in Princeton and generally acknowledged genius — and also a nice guy. (In addition to his multiple prizes in physics, Witten also won the Fields Medal — the “Nobel Prize” of mathematics.)
True, Witten is highly influential. But it’s hard to imagine him ruining an entire generation of physicists. They are not, in general, followers; getting them to agree on anything is like herding cats. They love nothing better than to prove each other wrong.
The claim that string theory can’t be tested is serious; experiment is the ultimate arbiter of truth. But it’s impossible to know what is ultimately testable. When the ghostly neutrino popped up in one of Pauli’s equations, the physicist admitted he’d done “a terrible thing. I have postulated a particle that cannot be detected.” Then in 1956, traces of neutrinos were seen in the wash of radiation spewing from newly commissioned nuclear reactors.
As for Woit’s claim that string theory has “absolutely zero connection with experiment,” experiments already planned for a new European particle accelerator will look for the existence of extra dimensions and extra families of particles — both predicted by string theory. In fact, many statements about string theory in these books are plain wrong. To say, as Smolin does, that string theorists are not trying to figure out how space and time came into being will surprise the dozens who do just that. To say, as Woit does, that fundamental mysteries about neutrinos are being ignored will come as news to the dozens of physicists who’ve been working on these problems for years.
So what good, ultimately, is beauty? As the late physicist Victor Weisskopf said, “What’s beautiful in science is that same thing that’s beautiful in Beethoven. There’s a fog of events, and suddenly you see a connection.”
Neither Woit nor Smolin sees the beauty in string theory. But perhaps they haven’t spent enough time in the fog. Theories often seem impenetrable at the time they are being discovered — and clear and simple (and beautiful) only in retrospect. One of the strangest charges against Witten is that he’s often openly muddled. Asked his opinion about a recent turn in string theory, he answered: “I just don’t have anything incisive to say. I hope we will learn more.” Smolin interprets this as Witten being “stumped.” Perhaps it’s a sign that he’s thinking.
In the end, Smolin admits that he hasn’t managed to do much better than string theorists, and his book is “a form of procrastination.” One hopes he will soon dive back into the fog and start making connections.
=== end quotation from L.A. Times ===
String theory: Is it science’s ultimate dead end?
http://observer.guardian.co.uk/uk_news/story/0,,1890340,00.html
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Well Smolin made an excellent rebuttal here:
http://cosmicvariance.com/2006/10/03/the-trouble-with-physics/#comment-123907
-drl
Spear Mark, that was really inspiring and somewhat scary.
-drl
Spear Mark the Second said:
“… the very large top quark mass is probably the central feature of the fermions in the Standard Model, and not a single string theorist predicted it …”.
Ari Heikkinen said:
“… Sean Carroll …[said]… “… If a latter-day Green and Schwarz were to produce a surprising result that convinced people that some alternative to string theory were more promising, it wouldn’t take long for the newcomer to become dominant. …”.
In the present climate of controversy over superstring theory, I think that one who produced a “more promising … alternative” would NOT “become dominant”, but would be attacked and ostracised.
In support of my view, I offer my personal experience:
For over 20 years
(published as early as two papers in the International Journal of Theoretical Physics (vol. 24 (1985) 155-174) and vol. 25 (1986) 355-403) , the papers having been received by IJTP on 27 February 1984 and 16 October 1984, respectively, around the time that CERN was claiming to have found the T-quark at around 40 GeV, prompting John Maddox to write a Nature article (Nature 310 (12 July 84) 97) headlined “CERN comes out again on top” )
I have espoused a physics model that in fact did and still does explain “the very large top quark mass”
(in terms of combinatorics and physics-related geometry motivated by, but not identical to, the ideas of Armand Wyler)
but,
far from me being a “newcomer” who has “become dominant”,
I have been blacklisted by the Cornell arXiv and characterized on the web as a “moronic crackpot” by Harvard’s superstring theory web-spokesman, Professor Lubos Motl.
One result is that, when I recently made an attempt at explaining the basic ideas of my constituent mass calculations, it was not posted on the arXiv, and can only be found on the web from my web site at
http://www.valdostamuseum.org/hamsmith/July2006Update.html#factorsphysics
and
another result is that, as Peter mentioned in another entry in this blog,
Michael Green is able to say (without fear of contradiction from the establishment) “There is no alternative to string theory. It is the only show in town – and the universe.”.
Still another result is that, if even only some part of my model turns out to be correct and useful, it will remain unknown to the established physics community because its members will not risk damage to their careers by investigating the work of a blacklisted “moronic crackpot”.
Tony Smith
http://www.valdostamuseum.org/hamsmith/
Come on, Lubos’ hardly a spokesperson for physicists or even string theorists. As far as I know most physicists aren’t string theorists anyway.
If someone says a writer of a paper is a crackpot claiming he’s wrong even thought it’s right then he’d ruin his reputation. It’s amusing to say that one person could ruin someone’s career. I think everyone’s well qualified to do that themselves.
I think the general public is more or less amused of physicists and theoretical physicists calling eachothers crackpots. It’s just a shame that good science projects get cancelled because scientists can’t get along.
And lets not forget that mostly taxpayers pay science. It’s just sad to know tax money goes for salaries of people who, instead of doing good work, waste their time calling eachothers crackpots.
As a retired academician / statistician and having just read Smolen’s book, a major premiss is not the physical unreasonableness of ST but that ST is a means of replacing the parametric problems in QM with another set in ST. The result is that essentially no progress is made. Smolens’ physical arguments are cogent, but to one who has been burned before, the charge of legerdemain of the parameters is striking, if true.