The String Theory Backlash

In October 1984, it was announced that the Nobel Prize for Physics had been awarded to Carlo Rubbia and Simon van der Meer, for the discovery of the W and Z bosons at the UA1 experiment at CERN just the previous year. This was the capstone discovery in the establishment of the Standard Model of particle physics. The third generation of fermions had already been discovered (the tau lepton by Martin Perl in 1977, the bottom quark by Leon Lederman also in 1977), and the nature of the strong interactions had been elucidated by deep-inelastic scattering experiments at SLAC in the late 1960’s and early 1970’s. Unsuspected by many, particle physics was about to enter an extended period in which no truly surprising experimental results would emerge; subsequent particle experiments have only been able to confirm the Standard Model over and over again, including the eventual discovery of the top quark at Fermilab in 1995. (Astrophysics, of course, has provided substantial evidence for physics beyond the Standard Model, from neutrino oscillations to dark matter and dark energy.)

A month earlier, in September 1984, Michael Green and John Schwarz submitted a paper on anomaly cancellation in superstring theories. String theory had been around for a while, and it had been understood for ten years that it predicted gravity, and was a candidate “theory of everything.” But there were many such candidates, each of which had run into significant difficulties when taken seriously as a theory of quantum gravity. Most people who were paying attention had presumed that string theory would face the same fate, but the Green-Schwarz result convinced them otherwise. A brief article in Physics Today was entitled “Anomaly Cancellation Launches Superstring Bandwagon,” and theorists everywhere jumped to learn everything they could about the exciting new possibilities the theory offered.

So here we are, over twenty years later, still with no surprising new results from particle accelerators (although hopefully that will change soon), and still with strings dominating the landscape (if you will) of theoretical high-energy physics. And still, one hardly needs to mention, with no clear path to connecting string theory to low-energy phenomenology, nor indeed any likely experimental tests of any sort.

In the circumstances, it’s not surprising there would be something of a backlash against string theory. The latest manifestation of anti-stringy sentiment is in two new books aimed at popular audiences: Peter Woit‘s Not Even Wrong: The Failure of String Theory and the Continuing Challenge to Unify the Laws of Physics, and Lee Smolin’s The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next. I haven’t read either book, so I won’t presume to review them, but I think we’ve heard the core arguments expressed on this blog and elsewhere. I’m a firm believer that it’s good to have such books out there; I’m happy to let the public in on our internecine squabbles, just as I’m happy to keep them updated on tentative experimental results and speculative theoretical ideas. It seems unduly patronizing to think that we can’t reveal anything to the wider world until everyone in the community agrees on it.

But I don’t actually agree with what the books are saying. Here is the main point I want to make with this post, trite though it may be: the reason why string theory is so popular in physics departments is because, in the considered judgment of a large number of smart people, it is the most promising route to quantizing gravity and moving physics beyond the Standard Model. I don’t necessarily want to rehash the reasons why people think string theory is promising — I’m not positing an objective measurement of the relative merits, but simply an empirical observation about people’s best judgments. Rather, I just want to emphasize that, when you get right down to it, people like string theory for intellectual reasons, not socio-psycho-political ones. It’s not a Vast String Theory Conspiracy, funded by shadowy billionaires who funnel money through Princeton and Santa Barbara to brainwash naive onlookers into believing the hype. It’s trained experts who think that this is the best way to go, based on the results they have seen thus far. And — here’s the punchline — such judgments could change, if new results (experimental or theoretical) came along to suggest that there were some better idea. The way to garner support for alternative approaches is not to complain about the dominance of string theory; it’s to make the substantive case that some specific alternative is more promising. (Which people are certainly trying to do, in addition to the socio-psycho-political commentating about which I am kvetching.)

That is, after all, the way string theory itself became popular. Green and Schwarz labored for years on a relatively lonely quest to understand the theory, before they were able to demonstrate anomaly cancellation. This one result got people psyched about the theory, and off it went. It’s not a matter of impressionable young physicists docilely obeying the dictates of their elders. Read Jacques Distler’s (absolutely typical) story about how he dived into string theory as a graduate student, despite the fact that his advisor Sidney Coleman wasn’t working on it. In a completely different field, listen to Nobel-winning economist Gary Becker on the response to his ideas (via Marginal Revolution):

“There was a sea change. I began to notice it in the 1970s and 1980s. A lot of the younger people coming out of Harvard, MIT and Stanford were very interested in what I was doing, even though their faculty were mainly – not entirely – opposed to the sort of stuff I was doing.”

This is just how academics act. They are stubborn and willful (even at a charmingly young age!), and ultimately more persuaded by ideas than by hectoring from their elders. And it’s not just the charmingly young — if good ideas come along, supported by exciting results, plenty of entrenched middle-aged fogeys like myself will be happy to join the party. If you build it, they will come.

There’s no question that academic fields are heavily influenced by fads and bandwagons, and physics is no exception. But there are also built-in mechanisms that work to protect a certain amount of diversity of ideas — tenure, of course, but also the basic decentralized nature of university hiring, in which different departments will be interested in varying degrees in hiring people in certain fields. Since the nature of science is that we don’t yet know the right answers to the questions we are currently asking, different people will have incompatible intuitions about what avenues are the most promising to pursue. Some people are impressed by finite scattering amplitudes, others like covariant-looking formulations, others don’t want to stray too far from the data. The thing is, these considered judgments are the best guide we have, even if they are not always right. Green and Schwarz were lonely, but they persevered. If you want to duplicate their success, find a surprising new result! You can’t ask a department to hire people in an area they don’t think is promising, just because it serves the greater goal of diversifying the field overall. Crypto-socialist pinko though I may be in the political arena, when it comes to intellectual life I’m a firm believer in the free market of ideas, and would tend to resist affirmative-action programs for underrepresented theories.

The bandwagons come and go, influenced by both data and new ideas. When I was in grad school in 1990, things were in a lull in fundamental physics generally, and students were escaping to Wall Street and elsewhere. The discovery by COBE of temperature anisotropies in the microwave background re-invigorated cosmology, and attracted a number of bright young theorists. The Second Superstring Revolution in the mid-90’s did the same for string theory. There’s every reason to believe that the LHC will do the same for phenomenology — the leading indicators are already easily visible.

The thing that has kept string theory alive is that interesting results have kept coming, from the 70’s (gravity!), to the 80’s (anomaly cancellation, five critical string theories), to the 90’s (branes, dualities, black hole entropy, AdS/CFT). The last few years haven’t witnessed their own “revolution” (unless you count the landscape), but it would seem a little impatient to give up on that basis alone. If nothing else, string theory is extraordinarily fruitful and robust. Indeed, the AdS/CFT correspondence says you can’t really separate field theory and string theory. Take an ordinary gauge theory in flat four-dimensional spacetime, and make it as supersymmetric as possible without adding gravity. Then make the coupling very strong, and the degrees of freedom rearrange themselves — just as the strong coupling in QCD makes the quarks and gluons rearrange themselves into pions and nucleons — into Type IIB superstrings living in a ten-dimensional spacetime. How amazing is that? It’s not proof that strings are connected to the real world (which, as people sometimes forget, is not manifestly maximally supersymmetric, and does in fact involve gravity), but it’s the kind of rich structure that keeps people optimistic that string theory is on the right track.

Of course, you do have to make the case that your personally favorite approach is a promising one, to the public and to colleagues in other specialties as well as to graduate students. This is not always a job that string theorists have done well. Some of them, I’ve heard rumors, can even occasionally be a mite arrogant. Let’s admit, this is something of an occupational hazard among academics; if universities fired all the arrogant people, the remaining faculty would be stuck teaching twenty courses a semester. And, while I think that an enormous landscape of stringy vacua might very well exist, I think that supporters of the idea have dramatically failed to take seriously the difficulty of actually calculating anything on that basis. Discussions about these crucial issues have all too often degenerated into sophomore-level philosophy-of-science debates, which haven’t done credit to either side. The truth is, we’re not doing science in a new way, it’s the same old way — trying to come up with the simplest possible consistent and coherent framework that explains the phenomena we observe.

And (to add one more “of course”), needless to say we need to keep our eyes on the prize, which really is explaining those phenomena. Sometimes people do get entranced with the math, which is fine, but as physicists the ultimate arbiter of interestingness is a connection to data. String theory hasn’t done that yet, and might not do it for a long while, but in the end will have to, one way or another. It’s hard! But string theory will either progress to the point where its connections to reality become increasingly manifest and specific, or people will lose interest and work on other things. That’s the way the system works.

Update: Interesting reports from the Strings 2006 meeting in Beijing from Victor Rivelles, Jonathan Shock, and Dennis Overbye.

226 Comments

226 thoughts on “The String Theory Backlash”

  1. Steuart,

    Thanks for your response, sorry if I misinterpreted your “below the belt” comment.

    I just finished arguing with the US publisher about the jacket copy on the US edition. They want it to be a forceful statement of a single idea designed to get people’s attention and stir up controversy. I’d rather it explain the much wider range of topics in the book. Unfortunately, there’s a limit to what you can do with a couple short paragraphs designed for marketing purposes, and I concentrated my efforts on just making sure that the controversial statements being made were ones I was willing to stand behind (yes, as an idea about unification, I do think string theory has failed). So, I urge people to not judge this book by its cover.

    I’ll also point out to any string theorists who want to complain about how this book is marketed that the only reason it isn’t being published by a university press, where it would likely be marketed differently, is that they stopped this from happening two years ago.

  2. Dear Amused and Jacques,

    For what its worth, anyone in the world of non-string quantum gravity would answer your questions differently from Jacques.

    “The whole thrust of Sean’s post is that high energy theorists tend to be a restless lot, descending on a “hot” topic, where progress can be made quickly, and then abandoning it for the next “hot” topic when progress slows.” (This and the quotes below from Jacques’s last post.)

    In our judgment this is why string theorists have not made more progress when faced with the major foundational issues such as the nature of space and time away from the semi-classical regime, and it is also why there are many open conjectures in string theory such as perturbative finiteness, S-duality, etc. Few think about these questions long and hard enough to get anywhere before the next “hot topic” takes everyone’s attention away.

    This was a very productive style of research when high energy theory was driven by many new experimental results but it has clearly failed over the last 30 years to go beyond the standard model.

    It is exactly for this reason that in our world we look for and reward young people who do substantial sustained work on hard problems, based on their own ideas.

    ” But any topic worth thinking about (stringy or not) already has (or has had) smart people thinking about it. There’s no way to avoid competition, unless you want to spend your time thinking about topics so obscure or intractable that they probably aren’t worth thinking about.”

    In our world there is little sense of competition because the best people young and old work on ideas and research programs of their own devising. One trades the challenges of competing to solve well defined problems in already established frameworks with the very different challenge of coming up with possible new solutions to persistently hard problems.

    “Besides, if you want your results to be noticed, it would probably help if there are some other people interested in the topic.” This is true in a community where people have little interest in original ideas. In our community the people we notice are those who surprise us with new ideas. And every year there are at least a couple of new people who get noticed for their new ideas.

    Unfortunately, as you imply, in the US the community of people who think about research in this old fashioned way is small and controls few positions, compared to those who think the style of research Jacques has described is the best way to do science.

    In science results matter, and I am willing to bet that it will become clear in the next years that the more patient, foundational and focused on fundamentals style of research is better at solving problems like quantum gravity, unification and the origin of the universe than the flashy, superficial, fashion driven style of research which succeeded so well from the 30s up to the mid-70s.

    Thanks,

    Lee

  3. The sad thing about Jacque Distler’s career advice, which seems perfectly sound, is that it brings to mind the distinction between advancing one’s career in physics and advancing physics itself.

    Advancing your career requires you to generate papers that other physicists will find useful in generating papers. Advancing physics requires that you to produce theories that better explain observable phenomena. While these objectives overlap, they are by no means identical. Were we as obsessed with advancing physics instead of our careers, we would simply shy away from all physics disconnected from the possibility of experimental refutation. We can’t do that, because we’d starve. We would, moreover, be throwing away any chance of being tenured. [How many times have you had to suppress your gut instincts, because you knew that the potential rewards of the research direction favored by your instincts were outweighed by the risks?]

    This goes a long way toward explaining the string bubble. Irrespective of its merits, strings generated a tremendous amount of employment for physicists. External observers, mistakenly believing that physics consists of what physicists do, overestimated strings’ status a physical theory. Unwarranted hyping didn’t help matters. And the sociological phenomena well described above by Part-Time Quantum Gravity Theorist also took their toll.

    The bottom line, it seems to me, is the presence of these huge built-in incentives to careerist behavior. Until this is corrected, theoretical physics will go from bubble to bubble. And the sort of steady (data-guided) progress of the first 85 years of the 20th century will never recur. I have no idea how to fix this short of somehow making anyone with the slightest interest in physics financially and socially independent.

  4. Lee paints an idyllic picture of a small community of selfless scholars, pursuing deep truths in a spirit of brotherhood and cooperation. It must be nice not to have those deep foundational thoughts sullied by considerations of how scarce resources (jobs, research funds) are to be allocated.

    But I think I’ll leave further investigation of the mores of different research communities to the sociologists (who are better trained to ferret out the true inner workings behind the stories groups tell about themselves).

    Instead, I’ll pick up on two physics points (off-topic for this blog post, but whatever…)

    …string theorists have not made more progress when faced with the major foundational issues such as the nature of space and time away from the semi-classical regime.

    I will cede to no one the deep insights that the string “duality revolution” gave into the intrinsically quantum-mechanical (“emergent”) nature of spacetime. They are far richer and surprising than anything anyone (no matter how clever) could have come up with by thinking deep foundational thoughts alone.

    there are many open conjectures in string theory such as … S-duality

    This is a beautiful example of what is known as a misplaced devotion to rigour. Proving S-duality of N=4 SYM would, first of all, require constructing the corresponding quantum theorie(s). (It is, after all, the statement that two different classical gauge theories lead to isomorphic quantum theories.)

    No one has rigourously constructed the quantum theory of any nonabelian gauge theory. Doing so for even the simplest one (“pure” N=0 YM) will win you a $1 million prize. Nevertheless, we have pretty good circumstantial evident that it exists, has a mass gap, and even have good numerical estimates of the spectrum of low-lying excitations.

    There’s also lots of circumstantial evidence for S-duality (see here for one rather striking check). It would be foolish to treat it as just another “unconfirmed conjecture.”

    It would be equally foolish to expect a young theorist to fritter away her would-be career in a vain frontal assault on proving it. (At least in the case of pure YM, she could retire on the proceeds of the Clay Math Institute prize, if she succeeded.)

    But, then I gather that Lee is working on embedding the Standard Model in the “rigourously constructed” LQG Hilbert space. Since the Hilbert space was rigourously contructed from the ‘git go, the properties of confinement and a mass gap in QCD will emerge as byproducts of his more ambitious programme.

    Lee, I look forward to sharing a good bottle of wine with you, when you collect the Clay Prize.

  5. Iblis, in your remark

    So, we cannot use our intuitions gained from experience in dealing with QFT and extrapolate that to write down the fundamental theory.

    You summarize the reasons for the success of string theory, neglecting any input from 4dim QFT and then from experiment. And I say, this is also the cause of the failure.

    It could be that the fundamental theory happens to be a very particular QFT plus a control of the renormalisation process. It makes sense to try to reorder the fields in the Standard Model to check for other ways to look at the Lagrangian, for instance as Connes Lott model did, or more modernly deconstructed models. It even makes sense to look into Bert Schroer suggestion where a Scalar Field is forced upon QFT as a requeriment of consistence. But people looks at all these things as a “-ph” Lego thing, meaning non fundamental, just model building, because all we know, hmm, that the low energy theory is to be always an effective theory no matter how do you alter it.

  6. Did you … umh … talk to the string theorists at Perimeter?

    Were they unadventurous and hostile to outsiders with new ideas?

    How about the string theorists at other places you’ve visited?

    Huh? Gosh. What I wrote was:

    If I ever run across a single String research group out there which is comparably adventurous and open to outsiders with new ideas, I can assure you I will hold them up as a model.

    Where did you get ‘hostile’ or ‘unadventurous’?

    What would you imagine that I might have said that would make them hostile? I think you are not getting it Jaques.

    What I see is that other groups now acknowledging a period of prolonged failure are using it as a clue as to what needs to change and how to make the next big advance through diversification. Since I don’t hear a comparable sense of failure within Strings, it is hardly surprising that there is not comparable openness to new ways of diversifying our efforts. If it ain’t broke, why fix it after all? The most I am aware of are some pointed remarks by Dan Friedan. Further, because so much of the structure within string theory is based on delicate relationships between exceptional structures, the field has never been particularly open to outsiders who do not first become resident within it.

    This wasn’t supposed to be an insult. It’s a strategy, albeit one in which I have less confidence during every passing year, but it could be the right idea if you guys are finally on the verge of an epiphany.

    As for hostility …. umh … may I ask you to look at your deliberate use of the interjection ‘…umh…’ in your question to me above and your provocative inference from my words.

    Do I need to spell it out? It’s eerily as if you wish to explain what I am talking about in terms of openness to outsiders by offering a specimen of prickliness as an example. And since you focus on hostility to outsiders, was it not you who famously used the phrase ‘net personality’ about a Callan student who teaches at Columbia and fellow blogger when what I think you meant was ‘physicist’. Probably just an oversight of course but one you might wish to clear up before debating this point further.

    As for PI, you are suggesting an experiment which I am reluctant to run as I met nothing but gracious people while there. But if you insist…I’d hate to shrink from an instructive excercise.

    I gave the general colloquium talk of the week on a Wednesday, left on a Friday and met and talked with absolutely everyone who came to my office, invited me to a meal or otherwise showed any interest in my work or my visit. That included what I thought was a fair spectrum of people. Off the top of my head, I remember meeting Baez, Smolin, Markopoulou, Hardy, Yidun Wan, Friedel, (Steven) Weinstein, Mann and some visitors from abroad. At your suggestion, I looked as many of them as I could remember up at the PI website and was not successful in finding one of them who identified as a string theorist. That seems statistically unlikely, so I will check again when I have more time. However, I had a broad smattering of conversations on everything from foundations, to emergent models of Riemannian geometry to spin foam models to markets. I simply didn’t have comparable conversations with String theorists. I hadn’t even thought about it as a test of the hypothesis until you posted so you can infer whatever you like.

    I myself would imagine that the sample size is too small to draw conclusions.

    Since this thread is getting old, let me make a suggestion.

    We don’t know each other, and I come in peace. I enjoy your blog which I use as a resource as I am presently spending some modest portion of my free time trying to figure out ways to increase the possibilities for funding scientists (including string theorists). Why don’t you make a leap of faith and assume that the suggestions and criticisms are well intentioned? I am happy to talk privately if you ever have some constructive suggestions for how outsiders can better appreciate what is going on in Strings these days. I meant what I said about the fact that I think you could do a much better job than Peter in telling us what we should be concerned about and how we outsiders can learn to better judge Strings as a part of our common portfolio of investments in science.

    Think about it. It’s not a trap.

    Best,

    Eric

  7. PK on Jun 22nd, 2006 at 8:39 am
    Science: Bell showed that in local hidden variable theories we can derive Bell inequalities (which are violated in experiment).

    This is a posting about string theory not Bell’s theory. If you want to know, Yang-Mills exchange radiation is the mechanism. You can discuss on my blog if you want. Must not go off topic of strings here.

  8. Looking quickly above I see the discussion has moved to the familiar “how awful are string theorists, let me count the ways”. I suggest each one of us will get his portrait taken with some kittens and puppies, just to demonstrate how lovable we really are, maybe that will put this tired old topic to rest?

    More to the point, Sean made some excellent points which are simply ignored. The questions is not the correct strategy for “diversifying portfolyos” other vague analogies people may have. The question is whether the decisions are to be made by professional phycisists

  9. (got trunctaed)… or is there a rationale for the usual decision making process to change, and if so precisely in which ways?

  10. Moshe,

    This is not about “whether the decisions are to be made by professional physicists”. Right now funding decisions are made by a mix of physicists and other interested parties who control the money (NSF and DOE people, university deans and other administrators, Fred Kavli, Mike Lazaridis, Sir John Templeton, and others). What I, Lee and Eric are suggesting in various ways is not that the roles played by these decision makers should be changed, but that all of them, physicists and non-physicists, string theorists and non string theorists, should be taking into account the failure caused over the last 20 years by a policy of putting most eggs in one basket, a basket that seems to have been poorly chosen.

  11. Peter, I have no experience with funding decisions, but personally have no objection for decisions-makers to consider all relevant facts and opinions, they probably do already. I am relieved nobody is suggesting any structural changes…

  12. It seems to me all very easy to talk about “diversification” and the like, but a lot harder to actually implement something in practice. Where are these great other ideas that we should be funding? Finding new ideas in quantum gravity turns out to be rather difficult. Given the choice, wouldn’t a student prefer to work on something that will lend itself towards a portfolio of research to show to prospective employes? Should we instead start anointing graduate students semi-randomly and give them tenure to work on whatever they feel like? I know that Lee would prefer us all to ponder deep philosophical questions, but what happens when someone spends seven years thinking about the nature of time and ends up producing nothing?

    So, how should we allocate the money? What advice should we give to graduate students (besides to go into cosmology or phenomenology)? “Diversify” just isn’t enough of an answer.

  13. Moshe,

    I’m finding it a bit difficult to believe that you and your kittens and puppies are that unaware of how resources are allocated in theoretical physics; the fact that one needs a paycheck to feed the kittens and puppies tends to make one pay at least a bit of attention to this.

    I don’t know about Lee and Eric, but my point of view is that at the moment relevant facts and opinions are not being considered by decision-makers, but if they start doing so, they will start making different decisions. One of these different decisions will be to change the incentive structure so that people are encouraged to try and do new things, not to work on an old idea that has clearly failed. Jacques Distler laid out for “amused” exactly what the incentive structure is that has led to the current failure.

  14. Part Time Quantum Gravity Theorist

    Yes, Moshe, you are right. The question is whether any part of the decision-making process should change and if so in what ways.

    There are standard ways of preventing groupthink – have a look at the wikipedia entry on groupthink for details. According to the article, the intelligence community is aware of groupthink and has mechanisms in place for dealing with it, but the WMD “presumption was so strong that formalized IC mechanisms established to challenge assumptions and group think were not utilized”.

    Whenever you have people involved in a speculative endeavor (and quantum gravity is definitely one of these), there should be mechanisms in place to prevent groupthink if these are known about. I have no doubt that string theorists would recommend the use of techniques to prevent groupthink for other communities involved in speculation, like the intelligence community. However, are they able to get beyond their belief in the infallibility of their own community? Would they even admit that the string theory community is exactly the type of community where groupthink is likely to occur – since they are bound together by a commitment to a particular speculation?

    I think Sean understands the string theory community well enough to know that they will insist that there is no need to prevent groupthink – their perfect minds will protect them. We might point out that groupthink will occur even when each individual in the group is acting perfectly rationally. That implies that groupthink safeguards are necessary even when such perfectly rational geniuses are involved. The intelligence community understands this (especially now, after they’ve been taught a lesson about it). Perhaps the anthropic string theorists would agree that the “monovacuists” (as Polchinski calls them) are suffering from groupthink and perhaps the monovacuists would agree that the anthropists are suffering from groupthink. But are safeguards needed? Why no; string theorists don’t need anything like that. String theorists can’t possibly behave like a cult. Their perfect minds will protect them.

  15. Peter, I know how money is allocated, I have no personal experience with the process. Once again, I’m all for decision makers to be as informed as possible, including reading your book and Lee’s, I was under the impression something different was being discussed.

    I know a bit more about hiring, so I am curious what you and others have in mind when they suggest to “diversify”, and how is that going to be enforced on individual departments?

  16. Part Time Quantum Gravity Theorist

    So Peter, would you agree that the best advice to give to a young graduate student today, who wants to have a career studying quantum gravity, is that he should study string theory? Any other advice would be bad for his career.

  17. Moshe (and Aaron),

    If the physics community as a whole develops a more realistic view of string theory, hiring committees and the people who approve their decisions are going to change the decisions they make, no one is going to have to “enforce” anything. Unfortunately I suspect that what is most likely to happen is that people won’t admit that the problem isn’t just string theory, it’s the faddish behavior that led to the way string theory was pursued, and committees will just change over to hiring in the latest faddish area of cosmology or phenomenology. What I’d really like to see is some serious analysis of what has happened over the last 20-30 years, and an acknowledgement that, lacking new experimental data, the field is in a tough spot. Ways need to be found to encourage people to try new ideas, ones that probably won’t work out, and having everyone jump on the same highly speculative idea is really no way to make progress. It’s not easy to come up with good ideas about how to do this and successfully implement them, so I’m not especially optimistic, but I strongly believe this is a discussion the field needs to be having.

    PTQGT,

    I’m not a quantum gravity theorist and not about to give advice to people who are sure that is the problem they want to work on, other than to advise them to make sure that they put the time into understanding what string theory and alternatives actually have accomplished or not accomplished, and don’t make decisions based on hype. I have no idea what this subject is going to look like 10 years from now, quite possibly string theory will be much less popular and going into it now will have been a bad career move. Under the circumstances, the thing to do might be to take the radical attitude of just not worrying about one’s career and doing what one loves.

  18. It seems to me all very easy to talk about “diversification” and the like, but a lot harder to actually implement something in practice. Where are these great other ideas that we should be funding? Finding new ideas in quantum gravity turns out to be rather difficult. … what happens when someone spends seven years thinking about the nature of time and ends up producing nothing?

    Aaron,

    You’re assuming that research in quantum gravity must be funded at similar rates year after year irrespective of progress, even if there are no fertile ideas. When explorers find themselves at the base of a mile-high stone cliff with a sheer face, they don’t try to chisel their way through it with a teaspoon or inch their way up it with a can opener. They explore elsewhere. In so doing, they invariably find another way around.

    Just as explorers plan their treks on the basis of how much ground they can cover, funding decisions should be based on the apparent potential for better explaining observable phenomena. Had this criterion held sway 22 years ago, it would have been clear even then that funds could have been more profitably invested in other areas of physics or even other sciences.

    With this criterion in place, the case of the young physicist wasting seven years thinking about the nature of time would no longer be an issue. He’d be thinking his deep thoughts at a patent office or other such employment. Unfortunately for him, funding levels in physics would have declined in direct proportion to the decline in ideas judged likely to explain observable phenomena. Just as throwing money at K-12 education doesn’t necessarily improve it (and it can be credibly argued that it harms it), so it is with physics. A harsh and counterintuitive reality, but it does seem to be true.

  19. pheno grad student

    Peter:

    I decided to follow up on your comment where you had made a count of string theory faculty a few years ago of the top universities and bring it up to date. I used slightly different criteria, including junior faculty since there really has been an enormous turnover of late(just look at the number of jobs listed on the rumor mill of late). Also since you included IAS with princeton, I thought it was only fair to include LBL with berkeley and SLAC with stanford since there is a high degree of overlap there as with the IAS. I took the top physics grad schools from US News(alphabetically ordered since they are so close to one another for the most part): Berkeley/LBL, Caltech, Chicago, Cornell, Harvard, MIT, Princeton/IAS, Stanford/SLAC, UIUC. (I didn’t go past 9 since I couldn’t find the 10th via free googling and can’t waste my money purchasing the full US news list…) The result I find is that in the high energy theory groups there are 40 active string theory profs, and 37 actve pheno profs(error bars are probably around +/- 5 depending on how often the groups web pages are updated). I find that number to be vastly different than the one you quoted from a few years ago. Granted we could be using slightly different cuts on activity level/definiton of a string theorist/definition of a phenomenologist, but I doubt the numbers would get so skewed as to get percentage wise 18/22 for strings with this counting.

    For my two cents I think this almost 50/50 setup for ph/th is a perfectly healthy distribution in theory groups as the cross fertilization in fields is very healthy, whereas with alternative QG theories there is almost no interaction with high energy pheno people due to the lack of connection they have to particle physics. Granted it is not 50/50 at each institution but the theory community is pretty small so it evens out nicely. Anyways I hope this quick count can be of some use. With all this everyone can feel free to spin these numbers any which way they want (as I am sure people will) but I just felt like putting some numbers out there…

  20. You’re assuming that research in quantum gravity must be funded at similar rates year after year irrespective of progress, even if there are no fertile ideas.

    I am? In fact, I’d guess that right now we are seeing a transition of funding to phenomeonlogy.

  21. For my two cents I think this almost 50/50 setup for ph/th is a perfectly healthy distribution in theory groups as the cross fertilization in fields is very healthy, whereas with alternative QG theories there is almost no interaction with high energy pheno people due to the lack of connection they have to particle physics.

    Re: cross-fertilization. Anyone want to count the number of papers jointly-authored between members of your cohort of 37 phenomenologists and your cohort of 40 string theorists (say, in the past 5 years)?

    I bet that number is considerably higher than a corresponding count done 10 or 15 years ago would have been. Of course jointly-authored papers isn’t the only product of cross-fertilization. But it’s certainly indicative of a trend which my subjective impression tells me is very real.

  22. Part Time Quantum Gravity Theorist

    Pheno, so you agree with Peter that the number of employed quantum gravity theorists who are not string theorists is exactly zero? But you think that employing “pheno profs” makes up for this.

    Why don’t you count the janitors as well?

  23. I’m sure the number of astrologers is also very small.

    Which is not to say that alternatives to string theory are like astrology. It is to bring it back to my original point, namely: whatever (im)balance of effort there may be between string theory and other approaches to quantum gravity and high energy physics, they exist because of people’s best judgments based on the scientific cases before them. And the balance can be changed in a hurry by the appearance on the scene of compelling arguments that some alternatives are actually more promising.

    If one simply wants to make the scientific case to physics departments and funding agencies (and graduate students) that string theory is over-supported and other promising approaches are under-supported, then: all power to you. Make the case, honestly and fairly, and I am suggesting that people will, for the most part, listen and judge honestly and fairly.

    If, on the other hand, one thinks that there is some non-substantive systematic bias that is distorting the balance away from what it would be on the merits, and that alternatives should be supported qua alternatives, because string theorists are narrow-minded and hegemonic and uninterested in dropping by one’s office or inviting one to their conferences, then I think you are deeply misguided.

    String theorists are made, not born, just as are the people who keep on funding them and hiring them (who, I repeat, are largely non-string-theorists). If you want to change their minds, get some good results that convince people you have an interesting alternative. Until that happens, people are going to keep pursuing the avenues they think are most promising.

  24. Part Time Quantum Gravity Theorist

    Sean says:

    If one simply wants to make the scientific case to physics departments and funding agencies (and graduate students) that string theory is over-supported and other promising approaches are under-supported, then: all power to you. Make the case, honestly and fairly, and I am suggesting that people will, for the most part, listen and judge honestly and fairly.

    No matter how many times it is pointed out to Sean that even people who are acting completely rationally and honestly are still vulnerable to groupthink, he will always pretend that he is unaware of this. He will therefore always suppose that if alternatives to string theory aren’t being funded then it’s because they shouldn’t be funded.

  25. Part Time Quantum Gravity Theorist

    Incidentally, Sean is preaching the infallibility of the group. He’s displaying groupthink for all to see. A textbook case.

Comments are closed.

Scroll to Top