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.
“Ashtekar, Bjorken, Connes, Laughlin, Loll, Penrose, Rovelli, Sorkin, ‘t Hooft, Thiemann, Wen.”
What a skillful interpolation of the unquestionably brilliant and of Lee’s own colleagues! Note how it entices the reader to consider, say, Thiemann as in the same class as ‘t Hooft. Also note how when Bjorken or ‘t Hooft talk about quantum gravity, they manage to sound speculative, modest, and curious about the ideas and insights of others. On the other hand, Penrose exhibits the same sort of closed-minded refusal to appreciate well-understood issues, and general lack of any clue about quantum field theory, that certain others exhibit. His undeniable brilliance and his past contributions don’t excuse his current arrogance and dismissiveness of the insights of others.
says Laughlin. 🙂
So in terms of microseconds, where do strings exist mathematically in the expression of “the arrow of time?”
Do not “reductionistic processes” allow us to think in this way?
Approaches to the Quantum Theory of Gravity by the PI Institute
Ah, group think by the benefits of Lazardis, Ummm…Qui Non? 🙂 What would you do with 40 billions dollars? 🙂
I don’t like string theory and I don’t really much like QFT either. My objection is though is not that the theory cannot make any predictions (since QFT can make predictions). Instead my view is very simply: What is the bottom line benefit of the theory i.e. What is the cost/benefit ratio. As far as I understand QFT is extremely complicated, very difficult to make predictions with and very difficult to compute anything with. So it has a very high cost and very few benefits. String theory has precisely 0 benefits and an even higher cost.
In my view a perfectly correct theory that you cannot compute anything with is perfectly useless. Also a correct theory that makes only 1 or 2 successful experimental predictions is also pretty useless. What is wrong with my view?
Science has always had a bottomline benefit since most theories did give us bottomline benefits. We could predict things with them and we could use our predictions to make machines. Areas like optics, statistical mechanics, chemistry, electromagnetics, etc are computable and they provided fairly immediate benefits. On other hand modern physics has only really given us Quantum Physics (to be honest I don’t really like GR either (although I do acknowledge that it does have the benefit of allowing us to tell some good bedtime stories)).
a different view,
So GR is akin to some bedtime story?
“Without GR and SR being taken into account, our GPS systems would not be so accurate in locating satellites. Time at different altitudes and different speeds run at different rates and any failure to take that into account results in GPS measurments being off by close to a mile in one day’s time.
GPS reception is built into cell phones to provide 911 emergency location information and provide position information for emergency vehicles. Hand-held GPS receivers provide position information for hikers, boaters, cars and soldiers lost in battle on the ground.
All those signals must travel up to the 4 satellites necessary that correct for clock errors and then back to Earth where receivers are. They take GR and SR into account.
GPS sytems are landing faster jets in shorter time than the navigators of the past who took up dangerous valuable time taking several fixes with their sextants.
Differential GPS systems guide our farm tractors along the ground to keep them going in very precise patterned lines to the accuracy of one inch, producing a more abundance of crop from our soils while reducing fuel consumption and time.
They are used by geologists to monitor the flow of glaciers and the growth of mountains. Oceanographers measure the scattering of GPS signals off the ocean surface and use the result to calculate wind speeds at the ocean surface. Engineers monitor deformation in such structures as dams and bridges using differential GPS to provide inch-level accuracy. Wildlifwe biologists place GPS collars in large mammals to study herd migration and ranging behavior”..(Wolfson-Physics in Your Life,lecture 31)
It can warn humans on the ground of potential weather disaster:
http://www.universetoday.com/2006/06/28/gps-can-predict-tsunamis/
QFT and string theory deal with gravity. We have already found out from experiments conducted on Columbia that plants in a free fall have their molecular structures affected. Moss forms into a spiral Fibinacci pattern in weaker spacetime structure that fails to do on the ground. Those plants that have those structures on Earth lost them in outer space. Understanding the interrelations between gravity and biological structures may reveal that certain viruses could one day in the future be withdrawn from a sick human and sent into orbit and be rearranged in a way to aid in a vaccine. Quantum gravity might be manipulated one day that may be able to isolate and withdraw leaking poisonous gases into containers..
If you want a better bottom line, try this: Forget about sending humans to a dead planet that robots and satellites are already accumulating enough data for our needs.
Lee,
as (for example) Sean hopes to be a textbook case as he wrote in his comment 152 and maybe others also, I am afraid that some physicists in the thread have not quite understood the point of the discussion. I am sorry if I am wrong.
As Sean says, once someone presents a successful theory in its complete form (or at least close to it), then everybody does get convinced and the theory becomes the mainstream. Yes, this is how science makes progress. The question is about the period when no one has yet shown a successful theory in its (almost) complete form. Does the free market of ideas in a science community maximize its productivity? Or is it actually not the best way to invest on ideas?
For example, when Sean says in his comment 148,
“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.”
I think that he has not quite understood the point of the discussion. It is not that string theorists are particularly narrow-minded. It is that people in general, and a community in general *might* have a tendency of “group think” (as you and some of the above people call it) that *might* not maximize the efficiency of the community toward progress. In other words, people in general might not be so open-minded as to maximize their productivity, and that some system might be needed to encourage them to listen to different ideas. Listening to different ideas from that which one advocates might stimulate her productivity more than otherwise.
I used a lot of “might” in the above sentence because this is an open question that I think no one is able to convince everybody of a single answer, especially because this is not a physics question.
In the end, although the “free market of ideas” might not be as efficient as we hope, it might still be the best system of doing science. Perhaps?
anonymous wrote:
I do not remember myself saying “anyone”. But i know many of them being forced to follow the string-brane way.
Your last “most of them aren’t talented enough in the first place” is just part of the stringy hype. String theory is difficult, yes, but no more than any other field.
Juan R.
Center for CANONICAL |SCIENCE)
The midsummer holiday was long and eventful, apparently so was this thread.
Arun said:
“The refinements to evolution came from increasing accumulation of the working of organisms, including how inheritance works.”
It was my impression that the fossil record, that I believe is the best evidence that evolution exists, wasn’t too impressive at Darwin’s time. He started out with scarcely little facts, but saw the power in his theory to explain much. Just as string theory currently.
island says:
“I believe that Lynn Margulis and others would tell you that they still don’t have it right.”
Perhaps – not all evolutionary theories are verified and new ones crop up daily. what I mean’t though was that Darwin’s correct ideas ideas was eventually validated.
Tony says:
“however, as I said above, it is not the type of evaluation that I “ask for”, nor is it an indication of that the world of physics is now a well-functioning free market of ideas.”
If the market of ideas is a real market, some products will be refused on packaging and/or content without any real inspection of the use and quality of the products. I agree that in the case of scientific ideas a more substantial inspection and/or refusal process could be asked for, but it’s the market buyers and ultimately consumers that rules that side of the process. Producers can only make as good as or better products than the competition to be ‘bought’.
Nigel says:
“Tony, this is the problem caused by mainstream speculation: the groupthink which asserts one speculative system without any empirical evidence for it, is the same groupthink which is not interested in alternatives.”
Not necessarily if the market analog is useful, see above.
I’ve read this thread with interest, observing some gems among the inevitable deluge of crud. However, something which really got my goat was the following:
Firstly, the arrogance displayed in this quote is quite simply breathtaking (and not a little nauseating). Secondly, as a current grad student in this area let me say that it is not at all representative of the mood within the field, at least among grad students. String theory is of course a difficult subject, but no more so than any other discipline. In fact, were I to be pushed on this, I can think of several problems in more traditional areas which are *far* more difficult than any I know of in string theory (a full proof of the Penrose inequality in GR, an acceptable definition of quasilocal mass, and a rigorous statement and proof of cosmic censorship are just three examples which spring to mind). Unfortunately, cretinous views like those quoted above do seem to be on the increase, particularly among those who have swallowed the string theory hype hook, line, and sinker (and let’s be honest, it *is* over-hyped: anyone who says otherwise is simply not living in the real world). It’s a damn shame that things are the way they are.
damtp_dweller wrote:
Still poor than that! String theorists, including the so-called smart ones, are pulling the subject in a completely incorrect and outdated way. It is very amazing to read an article on the topic or hearing some talk where presented completely crackpot stuff from some string theorist. People working in other fields simply receive the talk or the paper (or preprint) as the “joke of the day”. The problem is when undergrads, young impresionable students and the rest are the target. Then audience is seriously misinformed and that is not good for science.
It would be really difficult to summarize the crackpotism received from string theory authors during last decades (of course, this is not a criticism to any string theorist). But more difficult would be to select one single example. There are many known examples: Lagrangian theory, thermal properties, foundations of quantum formalism, unitarity, all the crackpotism about Landscape and CC, epiroktic scenarios, etc.
I think that my favourites are:
1) The completely outdated TFD Dp-brane theory, presented like “exciting” when reusing ideas implemented decades ago by other people (of course all string theory before TFD version was still more boring and oudated).
2) The claim that string theory is a TOE when does not verify the basic M2I equation of complex systems (equation working in macromolecular chemistry for instance).
3) The completely outdated ideas on recent version of non-critical string theory, copying stuff from the early 80s and copying incorrectly the equations! (e.g. equation (37) of arXiv:hep-th/9406016 v1 is both outdated and incorrect).
4) The insanity around Landscape and CC.
In last Quantum Future (1998), Claus Kiefer and Erich Joos wrote:
But what could one wait from researchers as Brian Greene?
Freeman J. Dyson (May 2004)
Juan R.
Center for CANONICAL |SCIENCE)
Sorry a typo!
As explained by Jean Marie Lehn (Nobel also)
Complexity = MI2
P.S: I checked that Nanopoulos preprint (and other works) is copying incorrectly equations, with one of the members of the group developing the equation in the 80s.
Juan R.
Center for CANONICAL |SCIENCE)
I actually figured as much, but I took the fact that it didn’t read that way to make the point that Lynn… “and others” would also tell you that there is a predispositioning among “neo” darwinists to willfully deny any and all forms evidence that carry implications that creationists might abuse.
She’s right about that, and I most definitely can give plenty of evidence that this non-scientific mentality isn’t limited to evobiologists.
My consistently expressed point is that this extreme “anticentrist dogma” is killing science, while obscuring our vision from the true road to the ToE, via the self-evident prediction that falls when it is noted that it is extremely probable that a truly special anthropic connection to the forces of the universe will also necessitate a reciprocal link to the human evolutionary process.
So the prediction that naturally falls from this is that there exists a mechanism which enables a universe with volume to “leap” to higher orders of the same basic structure… as inflationary theory and about a dozen other projected assumptions bite the dust to empricism.
Does such a mechanism exist?
Yes, and I’ve already defined it in this thread.
http://blogs.discovermagazine.com/cosmicvariance/2006/06/19/the-string-theory-backlash/#comment-35150
Now if we only had an honest scientist that wasn’t afraid of purpose in nature… like Einstein.
I would like to register a critique of the “marketplace” analogy. I think that ultimately scientific theories are about what is correct and what is incorrect from an explanatory as well as predictive mode. It is not Beta vs. VHS. (a side note here… Beta was in fact the better video format from a quality perspective but lost the marketplace battle). My concern is that if you start to consider “market value” of scientific approaches as measured by the number of people who are attracted to work on that approach or how much funding it can attract, it will encourage inertia in that people who have already invested and received support for “Brand X” will be inclined to continue along that path lest they explain to the funding source that they are switching to “Brand Z” which may include an implicit admission that the work on “Brand X” was not fruitful.
Please note nothing in this comment should be meant to implictly or explicitly be critical of any of String/Brane, QFT, LQG, Info-theoretic models, or any other alternative theory. I am simply worried about the use of a marketplace analogy when the marketplace is by its very nature, inherently bound up in establishing and defending “brand identity” and therefore encourages continuity vs. reexamination.
Elliot
Elliot,
I would like to expound upon your insights into the concept of a market-based approach to pure-science research…
I will initially point out that society has become overly obsessed with the notion that unadulterated, unabated Capitalism is compatible with all sectors of our economy. Furthermore, I will take note that there are some extremely valuable products/services within our economy which are simply not amenable to a market-driven economy. Unquestionably, research in pure-science falls under the distinct category of products/services which should be regarded as lying outside the range of free-market economics.
Because the “pure-science” sector of our economy is negatively correlated with direct and immmediate profitability, this particular sector should be granted exemption from having to adhere to marketplace economics. More importantly, we – as a society – intuitively comprehend that our financial vitality and societal well-being is positively correlated with progress made in the realm of fundamental science. Simply put, a society’s long-term profitability hinges upon having a viable infrastructure for pure-science research. Moreover, because the free market is generally not receptive to funding such venture-capital projects, society must look beyond Capitalism in order to support fundamental science.
Perhaps laissez-faire works remarkably well within the marketplace of PC’s versus MAC’s. By contrast, laissez-faire fails to deliver when it comes to unveiling Nature and/or uncovering the origins of the universe.
Cynthia,
I do not think that the “market place” analogy discussed in the thread is about “market value” of scientific research. I think it was what some people called “an analogy to a portfolio”: the comparison between investment on financial goods and investment on developing ideas in sciences.
Eric’s post 87 is I think a good summery of a motivation for the “market place” analogy, and let me paste a part of it:
“What is being seriously discussed is how to properly evaluate and diversify imbalances in the portfolio of approaches to advancing fundamental physics beyond the Standard Model and General Relativity.”
So, protecting fundamental science from evaluating potential “free market value” of research and investment according to the evaluations is not the topic discussed here. The question that has been raised is: “what if an alternative approach (of a topic in sciences in general), not the most popular approach, was on the right track and we would have noticed it a lot earlier had we invested on ideas more cleverly.” The question is about the method of investment on scientific research purely for the sake of the progress of the science itself, not for the sake of Capitalism.
Cynthia/A Chinese Student,
You are both correct. However to clarify my point is that when you use the marketplace analogy, (with or without financial payoff), you inevitably get dragged into establishing and maintaining brand identity. “Strings” in marketplace terminology is a brand name for a theory of everything. As a “brand” it has certain positive and negative attributes. But the notion that this is the correct way to look at pure science is troublesome and may bear on the process of making “investment” decisions on one approach or another even given the fact that the payoff is not financial.
My point is cautionary in that when you begin to use analogies such as these, there are some consequences that come along that may not be intended and may be counterproductive.
Elliot
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Sean,
Regarding your article ‘The String Theory Backlash’, you state that you have not read either ‘The Trouble with Physics’ or ‘Not Even
Wrong’ and yet you go on to say the that you disagree with what the books are saying! Is that
not stretching your credibility to a rather pointless singularity of meaninglessness.
And unfortunately it seems to reflect too well
the string theorists disregard for any requirement for experimental prediction or evidence. The Emperor truly has no clothes…
Best regards
Well, I did read the titles of the books, complete with subtitles, which was really all I needed to know there was a disagreement. And I made the reasonable-seeming assumption that the content of the books would be compatible with the public statements made by their authors in multiple venues over a series of years. And now that I have read them, that assumption was correct.
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