Maclean’s has been publishing a very nice series of articles about Perimeter Institute by Paul Wells. These include one about Jacob Barnett, a 15 year-old who is now studying in a master’s level graduate program (Perimeter Scholars International) there. Another piece, about other students in the program, is here. It discusses one somehow oddly familiar story, of a “young man with dark hair…seems too cool for school”, born in Iran, but educated in Canada, on his way to a promising career in particle theory, Nima Afkhami-Jeddi. There’s also yet another piece, with a wonderful description of the bistro at Perimeter.

In the most scientifically substantive piece, entitled Perimeter Institute and the crisis in modern physics, Wells describes PI director Neil Turok’s welcome speech this year. Here are some quotes from Turok:

Theoretical physics is at a crossroads right now…In a sense we’ve entered a very deep crisis.

You may have heard of some of these models…There’ve been grand unified models, there’ve been super-symmetric models, super-string models, loop quantum gravity models… Well, nature turns out to be simpler than all of these models.

If you ask most theorists working on particle physics, they’re in a state of confusion.

The extensions of the standard model, like grand unified theories, they were supposed to simplify it. But in fact they made it more complicated. The number of parameters in the standard model is about 18. The number in grand unified theories is typically 100. In super-symmetric theories, the minimum is 120. And as you may have heard, string theory seems to predict 10 to the power of 1,000 different possible laws of physics. It’s called the multiverse. It’s the ultimate catastrophe: that theoretical physics has led to this crazy situation where the physicists are utterly confused and seem not to have any predictions at all.

The data just fits so perfectly with Perimeter’s mission. If it had turned out to be complicated and messy — 10 new particles at CERN and all kinds of funny evidence for models of inflation and stuff in the sky — one would have to say the future of theoretical physics does look pretty messy and complicated. Perimeter would be just one of 100 such institutes.

But given that everything turned out to be very simple, yet extremely puzzling — puzzling in its simplicity — it’s just perfect for what Perimeter’s here to do. We have to get people to try to find the new principles that will explain the simplicity

Turok’s perspective on the current situation is great to hear. It’s wonderful to see this kind of admission that the evidence is now in that particle theory has been barking up the wrong tree, coupled with a vigorous position that looking for new principles is where the future lies. My only comment would be that Turok might want to think about bringing in to Perimeter more mathematicians, since if physicists are going to look for new principles, they might need some new mathematics.

For another similar take on the current state of theoretical physics as it faces up to the fact that our simplest theories of particle physics and cosmology are working all too well, see Adrian Cho’s Boxed In at Science magazine.

In the US, HEPAP was meeting last week to discuss the Snowmass workshop and the process for going forward with recommendations about the future of HEP. There was a report from the DPF Panel on the Future of High Energy Theory. It had nothing about the intellectual crisis that Turok and others see in the field, with the only crisis addressed the difficult budget situation, leading to cuts in grants. The panel recommends that theorists continue to get two full months of summer salary, and argues that “salary caps” limiting the size of these payments should not be lowered.

**Update**: Physics World has something about this, with the headline Perimeter Institute welcome speech reignites the string wars.

My guess is that the crucial insight will be more philosophical/interpretational than mathematical. Likewise, the Lorentz transformations were discovered and analyzed

in the context of electromagnetismalmost 2 decades before Einstein came up with special relativity. My vague impression of Perimeter is that most of the folks there would agree, although I certainly can’t speak for them. But sure, bring on the mathematicians. Maybe their impressiveness will counter-balance the stigma of quantum foundations.Peter, if you compare the list of seminars and other talks at PI now vs many years

back, when it was formed, earlier there used to be lots of talks on non-trendy topics

and including by people who usually don’t give talks elsewhere.

whereas nowadays most of the seminar are on the usual fad topics.

“[…] might want to think about bringing in to Perimeter more mathematicians, since if physicists are going to look for new principles, they might need some new mathematics.”

Well, this might be a bit premature, don’t you think? What branch of mathematics do you think it will be needed? Fortunately you are not the Perimeter’s director!

Noname,

“premature”? Do you think that if the crisis in theoretical physics gets worse, that will then be the time to call in the mathematicians?

I’m not sure why you find the idea of a few mathematicians amongst the hundreds of physicists at Perimeter so threatening. Actually, I hadn’t realized that Perimeter now has Mathematical Physics as one of its nine research areas. Between that and Nima Arkani-Hamed’s interest in motivic Galois theory, the inroads of mathematics at Perimeter may already be more advanced than I realized.

One thing I think we can both agree on is that it’s very good that I’m not the director of Perimeter. For one thing, I don’t have much in the way of good ideas about who they should hire. As for promising fields of mathematics, given the huge past success of symmetry arguments in fundamental theory, there’s a name for the field of mathematics that deals with such symmetry arguments (representation theory), and that would be one obvious place to consider.

“nature turns out to be simpler than all of these models”

This seems like a very strange thing to say. It sounds like Turok thinks we’ve found everything out already, and it’s not complicated! In context, he’s talking about the combined discoveries of Planck (strong confirmation for the Lambda-CDM concordance model) and the Higgs, more or less capping the particle zoo of the Standard Model without providing any clues (yet) to what lies beyond. But to call this “simple” seems a misuse of the word. 3 generations of fermions? “Who ordered that?” A light scalar: how does that work? Another scalar that drives inflation. What is it? Stable probably heavy non-baryonic dark matter and a non-zero cosmological constant 10^-120 times its “natural” value. What are they? And how does all this hang together into a coherent whole? This is simple?

The crisis is the gap between the limits of the methods that served so well since the 1930s and the energies that we need to investigate. In the face of that gap, theorists are doing what they can. But they’re not just confused – as Turok notes in the fuller context, they’re depressed. He goes on to say things promoting the PI as a route to fulfillment, which is part of his job, so one can forgive his rhetoric. But what’s your excuse? You wear your schadenfreude on your sleeve. It’s an entirely worthy thing to mock hype, which you do ably. But it seems perverse to take pleasure in the hopelessness of so many who’ve been at the forefront of discoveries and theoretical inventions that have taken us so far, and are now stymied.

Foster,

To my mind, Turok is just making the obvious point that we don’t have any good ideas about how to get beyond the SM, that the heavily oversold ones of the last 30 years were always too complicated to be plausible, and now in addition have had their hopes for some experimental confirmation shot down, thus the “crisis”.

My reaction to what Turok has to say is not “schadenfreude” at all, but optimism to see someone influential making these obvious points that I and many others have been making for years. He’s quite right that the theory community should acknowledge the situation and act accordingly, not by being “depressed” that the unpromising ideas many had been working on are getting shot down, but by looking for something new to try. To be blunt, I have little sympathy for those “depressed” that the techniques they know and love have run out of steam and no ideas or interest in coming up with others. People working in this area are smart and capable of doing many things with their lives, and if they don’t see anything worth doing in this field, they should move on to a different one and open up space for those who do have ideas they want to work on.

Hehe. It is encouraging that people like Turok starts to acknowledge the crisis in physics. After another ten years of crisis, maybe people will even start to look into new non-trivial extensions of gauge and diffeomorphism algebras 🙂

But then again, whom am I kidding. We all know that the ultimate goal of theoretical physics is to worship Ed Witten by chanting magic and mystery.

When I was a kid I was sleeping with a CERN print and I was explaining the Hawking radiation to my friends by impersonating a black hole, eating cherries and spitting the kernels. Later I got converted to mathematics. Now, my impression is twofold: on one side, there’s a lot of new math which could benefit to physicists and on the other side, boy, understanding biology is far more interesting and challenging than physics.

Is there any legitimate evidence that Jacob Barnett is actually autistic. Highly intelligent, unusually behaving, late-talking, children are quite often misdiagnosed as being autistic when they are not autistic at all. Maybe Jacob Barnett got caught up in the Autism Dragnet.

Sorry for the useless joke, but “Nima Afkhami-Jeddi” is Nima “Arkanimedish” AND a Jedi?? This guy is set for life…

if i was a teacher in math, i would say that the counting is wrong, and even the evaluation of the perimeter is doubtful.

in fact, taking a renormalizable gauge theory su(3)xsu(2)xu(1) with sm content, the number of parameters is 20 not 18 (3 mixing, 1 phase, 9 masses, 3 parameters in the scalar sector, 3 gauge couplings, 1 strong cp phase). and i doubt that a reasonable counting of the parameters of a grand-unified-theory can be done, without declaring the theory that you want to discuss.

but what is worse is the statement “If you ask most theorists working on particle physics, they’re in a state of confusion.”…. “most theorists”? when, for god sake, mankind made a step forward in theoretical physics using polls?

fuzzy,

I suppose one can argue that dimensional transmutation allows one to trade one of the gauge couplings for a choice of mass units, and the strong cp phase getting somehow set to zero isn’t really an undetermined parameter but a structural aspect we don’t understand. That would give the 18. A more serious problem is that this count doesn’t include neutrino masses and mixing angles.

The strong CP phase has to be experimentally determined in the standard model and we only have good bounds on it — but we may yet discover that it is non-zero in the improved sensitivities of neutron and other EDM experiments in the next 5-10 years. So it is a bonafide parameter.

In the Higgs sector there is only its mass and VEV — so 2 parameters.

And then there are the neutrino mass and mixing parameters as well, but maybe these are being considered as beyond the standard model parameters.

hi friends, let me insist, assuming we are theorists. if we can agree on counting, maybe we can do physics.

the parameters ought to be counted by using the rules of the game. and the rule of the game are three: “gauge invariance, renormalizability, selected representations”.

with these rules

1) neutrino masses are out from sm. this proves that the sm is not correct, but this is another story that does not pertain to the “counting of parameters in the sm”.

2) the scalar potential contains a constant, that has to be counted (you can call it the cosmological constant, if you want to call it somehow)

3) the theta term is a honest gauge-invariant term, it is also there in the heap of parameters. all we know from experiments is that, assuming that the sm is correct, it is small.

the fact that we want to understand neutrino masses, cosmological constant, reason of conservation of cp in strong interactions (and we don’t) does not change the counting of the parameters in the sm.

(apart from disagreement, i do not understand one of your arguments peter: if you consider dimensional transmutation, you do not change the number of parameters; alphas or lambdaqcd makes always one, from the point of view of counting)

The mainstream of physics is still condensed matter and optics. There is no crisis there, rather constant and impressive progress. You do a disservice speaking of a “crisis in physics” when you mean something like a “crisis in particle physics” or a “crisis in high energy physics” (both probably still too overbroad).

Fuzzy,

“2) the scalar potential contains a constant, that has to be counted (you can call it the cosmological constant, if you want to call it somehow)”

Please, please don’t call that parameter the “cosmological constant”. At the very least, calling it that way is very bad terminology, as people might confuse this parameter with the actual experimentally observable cosmological constant.

Adding to your rules of the game, I’d just note that:

(a) gravity is to be considered BSM (due to your renormalizability requirement) and consequently there is no cosmological constant (the real one) in the SM,

(b) the constant parameter in the action is completely unobservable within the SM, and should not be treated as a bona fide parameter.

The additive constant in the SM action (or any other flat-spacetime theory) can couple only to gravity, which is BSM by definition. Without gravity, this parameter is not observable, and can be freely set to anything you want, including zero. So it can be removed from the SM with no difficulties, and it should not be counted as a proper parameter.

And again, please don’t call it the cosmological constant — the *real*, observable cosmological constant is a parameter in GR, it measures the non-flatness of spacetime, and has absolutely nothing to do with the constant parameters in flat-spacetime theories like the SM.

Best, 🙂

Marko

marko i agree that it is better to say that the sm has 19 *observable* (or potentially observable) parameters.

i am instead confused by the statement that the cosmological constant is purely gr; perhaps you mean that gr is a self consistent theory that does not need the sm, and we can use some simpler treatment of the matter when doing cosmology?

thanks again! 🙂

Fuzzy,

We’re getting off-topic here, but since you asked…

“i am instead confused by the statement that the cosmological constant is purely gr;”

Why is that confusing? The cosmological constant is a parameter in Einstein equations of GR (and some other models of gravity, but let’s not get into that), and is being measured through its gravitational effects. One particular effect of nonzero CC is that the Minkowski flat spacetime is not a solution of Einstein equations.

On the other hand, the SM is defined precisely in flat spacetime, which means that it ignores both GR and the CC itself. The SM action is defined up to an arbitrary additive constant, which cannot be measured in any SM experiment, and is therefore usually set to zero. Being introduced in flat spacetime, this constant has a priori nothing whatsoever to do with the CC.

Now, if one couples GR and SM (classically only, quantization has lots of issues), the arbitrary constant from the SM sector and the CC from GR sector sum up into a single resulting parameter, which is also called CC. Experimentally, the CC has been observed to be positive (by gravity-related measurements), leading to the acceleration of the universe. While one could in principle say that the free parameter from the SM gives a contribution to the observed constant, there is no other way to measure that parameter on its own (non-gravitationally). Therefore the easiest thing to do is to set it identically to zero, and have only one parameter to be called CC — the one which was present in GR from the beginning.

I hope now it is more clear. 🙂

“perhaps you mean that gr is a self consistent theory that does not need the sm, and we can use some simpler treatment of the matter when doing cosmology?”

I did not try to say anything about the self-consistency of GR, SM, cosmology or otherwise. 🙂

Best, 🙂

Marko

Please, enough about the CC…

Lets be fair. I see some in the HEP community stubbornly refusing to acknowledge reality… but I see many other prominent names doing exactly what Peter (and many others) have been suggesting. That is, looking for more fertile ground. What do you think this whole firewall business is about? Have you paid attention to Witten’s work the last few years? Many of the saner minds in hep -are- looking for new approaches and directions. We should not expect a public mea culpa as that could harm all of science funding. But we should “privately” acknowledge and encourage the change of tack.

I’m just curious to know what Peter would do if SUSY is discovered in the next LHC run. In my opinion the only honorable reaction would be to close down this blog. Peter, if you answer, please don’t say this will never happen. I’m interested in your reaction if it does happen.

imho,

I disagree with you that this is a discussion that should only be held privately to protect funding. What has actually been happening over the past decade or so is that as the problems with string theory and SUSY have become more apparent, the refusal to publicly admit this, and the choice to start adopting multiverse pseudo-science instead, has damaged the interest of HEP theorists immensely. Look at it this way, if you’re a non-HEP physicist trying to decide whether to hire in HEP theory, having HEP theorists saying that past ideas haven’t worked out, but they’re moving on and trying to find new ones is not a strong case to hire them, but it’s something. If instead you’re being asked to hire people who refuse to admit that what they’ve been working on doesn’t work, you’ve got a very strong case not to hire them. I think Turok has it right: make lemonade.

Noname,

Unlike some physicists, I don’t have a problem with the fact that sometimes I’m wrong about things. If the LHC sees the kind of SUSY that I don’t think has ever been very promising, I’ll have been wrong, and will discuss this not just privately, but publicly. I’ll also be fascinated to try and understand the implications of what the LHC does see. If it turns out it’s a complicated SUSY effective field theory of some random point in the string theory multiverse, and none of the various ideas about representation theory and physics that I’ve been thinking about go anywhere, I’ll give up and do something else with my time. This might become a blog about number theory and Shimura varieties…

Peter –

I’m not sure if you had a chance to listen to all of the video of Turok’s welcome for the new students. A bit later in the video he says that what string theorists are really doing is playing around with different pieces of mathematics. So perhaps when Perimeter hires a string theorist, there really are hiring mathematicians.

Hi Peter, we should hold a public discussion to what benefit? The public discussion over the last decade has been helpful no doubt, but it seems to me we’re seeing power law behavior at a critical point. A new phase is coming. Is it still useful to air dirty laundry when most everyone agrees there was a problem and many are taking steps to correct said problem. Shouldn’t we keep in in the family? Or perhaps we need to make a distinction between those changing tack and those stubbornly steering towards the iceberg… Maybe I’m wrong.

Geoff,

Problem is that mostly string theorists aren’t mathematicians or doing mathematics. Some of them are and that’s great, but the assumption that string theory=mathematics is just wrong (as an extreme example, consider the string theory anthropic landscape).

Actually I see that Perimeter divides things in a reasonable way, with a “Mathematical Physics” research area and a “Quantum Fields and Strings” research area, with only some of the QFT+string theory people listed in both.

Im completely flabbergasted at the things Turok thinks he’s justified in saying. As Foster rightly points, he speaks like someone who’s had some kind of divine revelation of the solutions to all nature’s problems. The known problems with the Standard Model in 2013 are just the exact same problems that were known in 2003, and Neil Turok is in no position to declare the solutions to these problems “simple” or “complex” or anything else, because they remain

unsolvedproblems!Besides being confused about the difference between fundamental and effective field theories, the difference between parameters and vacua and “laws of physics” (confusions all also promoted by this blog) Neil’s main thesis is also complete nonsense. There is only exactly one thing that could be called a “crisis in physics” and its really more of crisis in economics: the fact that substantially novel data costs on the order of $10 billion or more to obtain. There is no “crisis” in having a description of nature that works perfectly well up to the energies that can be accessed by such a machine (if that is the case, which is far from certain). There is no “crisis” in having accumulated detailed parametrizations of as many scenarios as possible that are known to be consistent with all existing experimental data. And certainly there is no crisis that will be solved by stopping theorists from constructing new models.

Its natural that some people will find that the most powerful BSM ideas unpalatable to their intuition, and theres nothing wrong with that. But if this intuition is grounded in truth then there will be some other framework from which we can derive QM, GR, Yang-Mills, the Higgs mechanism, and every other major component of empirical reality, and that framework will have nothing to do with SUSY or strings. Well I would be very interested to learn that you’ve found such a completely new framework, but I don’t think we ever will, because I think that intuition is obviously wrong. But in either case, for now, thats all it is: intuition.

Fiber Bundles! That’s where it’s at!

Thanks for the post. I also agree that more mathematical physicist (people like Wigner) who has mathematical vision and physics intuition can be really useful. I also agree that string theorist can not replace mathematicians in the field. To my understanding they just play with this and that, not necessarily having the deep mathematical vision.

Additionally, as a person who was in the field, I would say I did not see much flexibility in accepting new ideas. I am sure the next Einstein is already changed his field to “finance” or something else.

For a fundamental breakthrough, I believe that we need more mathematicians, more open positions, more passion, and less dogmatism.

“the assumption that string theory=mathematics is just wrong (as an extreme example, consider the string theory anthropic landscape).”

Calm down about the multiverse! Hardly anyone is even studying that stuff. Probably around 80% of the papers on hep-th are looking at formal, mathematical problems in QFT and string theory. You’re so obsessed with this multiverse business that you’re completely ignoring the reality of this subject.

Bob Jones,

The multiverse stuff might not be in the hep-th front line

(and here I have serious doubts… check this out: http://arxiv.org/find/all/1/all:+multiverse/0/1/0/all/0/1)

, but in any case certainly is in the of the spotlight of the outreach arena, which is the “welcome card” of our field. Almost every popular book and article mentions it, it appears on TV in several programs, the list is unending. And, it seems to me that the number of bullshit hep-th papers is increasing and not decreasing. A sign of the times is to see a talented fellow like Sean Carrol writing some crazy article about “Botltzmann brains”.

Peter might be more concerned than the rest of the field, who so far seems to just ignore as an embarrassment not worth mentioning. Whether ignoring will make it go away or make it worse (increase bullshtiness in hep-th), time will tell.

Bernhard/Bob Jones,

The multiverse was only being mentioned here as an extreme example, no need for more discussion of it here. More to the point, my comment was about string theory, and Bob Jones responds by arguing about “QFT and string theory”, which, if you care about what words mean, is something different.

If anyone has some actual data on what fraction of hep-th articles are about string theory and are of the sort that a mathematician would describe as serious mathematics, that would be interesting. Otherwise though, enough…

String theory is not mathematics, I agree with you about that. But it’s still *mathematical* in the sense that most of the time string theorists do not even attempt to postulate new physics. Instead, string theorists are generally interested in conceptual questions in quantum gravity and applications to formal problems in quantum field theory. They’re not coming up with new laws of physics but deducing consequences from the theories that are already known to be relevant for describing nature.

Although it is good to hear someone from the Theoretical Physics community admits to the current crisis, one is tempted to think it might not be an accurate reflection of what physicists at PI believe. I have met with several PI faculty members and students. They generally and mostly (not exclusively though) expressed a snobby attitude. I believe members of the String Theory group at PI must be convinced that String Theory is the way, otherwise they would abandon it. If Turok is really serious about working on finding a solution to the current crisis, then a plan for adopting new directions should be implemented. One thing could be hiring mathematicians, like you suggested. I also think it would be very useful if there are more practical projects invested in, for instance projects that can provide theoretical predictions verified by EXPERIMENT. To my knowledge there is one or maybe two theorists at PI working on problems that may (?) connect to experiment. PI can express greater interest in Condensed Matter Physics and AMO Physics. For now, I feel probably the most useful work at PI is in the context of Mathematical Physics. Also, there could be projects held in connection with the philosophy of physics. After all, philosophy and physics were connected for a long time.

I would be interested in your opinion, Peter.

My gut feeling, somewhat along the lines of what Jess Riedel and JK allude to, is that the crisis will be solved not by physics but by philosophy. I do not know intellectual history well, but certainly we have found ourselves in this position before–apparently stymied, unable to progress. Yet our problems were, in time, solved by a deep, simple, and in retrospect obvious philosophical insight. Whether it’s the Copernican Revolution or Einstein’s insight into (e.g.) the relativity of time, cleverness or technical skill didn’t do the trick. Instead, it was a willingness to think “outside the box” and against the orthodoxy.

If I were a physicist, I would study intellectual history to identify situations similar to the one we find ourselves in now. Then I would examine how those situations were eventually resolved, with an eye toward the general philosophical outlook, the conceptual leaps, etc. that were involved. That would not provide us a solution but at least would suggest the approaches and persons likely to succeed.

On these grounds, string theory strikes me as dubious. It strikes me as similar to the ill-fated effort to explain the geocentric orbits of the planets through ever more complicated mathematical systems of epicycles upon epicycles. Contrast this to Einstein; he didn’t invent any new mathematics at all as far as I am aware. Instead, he took from Lorentz, and then from Riemann. But he just had that fundamental philosophical insight that was right for the time.

hi LogicFan, i agree with you, and would like to add a thing.

a trivial principle is that we should not support an idea in which we are not convinced, but it is much easier to avoid confrontation with ideas and with people, and rather, accept “this” since it is fashionable, “that” since it gives me a grant, or since the research center where it is studied is so respected, etc.

we need critical and open discussions among physicists! if a colleague working in condensed matter, or astrophysics, is not convinced by the validity of a certain plan or idea concerning particle physics, this is a good reason to reduce fundings. i mean, physicists should take responsibility of a serious and responsible community, we cannot accept self-referencing.

the usual objection i receive to this description is “it cannot be so”! but please, go to any specialized conference in strings or susy and tell me how many people come to progress in science or to understand something new, and how many to participate in the social event. (tip: one of the two numbers is usually zero)

coming back to the discussion of turok, i do not like his ideas. as i argued above, he is not taking theory seriously, because one cannot speak so loosely: “the sm has 18 parameters” (and as we discussed, this is not true: the parameters are 20, 19 of them are observable) or worse “this class of theories has 100 parameters, the other has 120” (which theories!!?? nobody cares of what he is speaking of???)

i highly dislike his argument “things are puzzling for its simplicity and this justifies our institute”, since I am also a fan of logic, and this argument has nothing to do with logic, it is pure rhetorics! for me, what it is really puzzling is not that some people are free to discuss anything they want, but rather, that nobody ever asks them “but where all your predictions of yesterday have gone? what is your contribution to the physics?”

JK/LogicFan,

Experimental condensed matter and AMO physics is pursued by most physics departments in the US and Perimeter’s mission is explicitly to try and do something different. I also don’t know of any promising ideas about experimental HEP or cosmology work that are not being already actively pursued.

As far as philosophy goes, since its founding Perimeter has had much more involvement in that (via Lee Smolin, for instance) than just about any other physics institute I know of. This is also a topic that has been well-funded in recent years (see the Templeton-funded efforts in “Philosophy of Cosmology” as an example). I’m a skeptic about prospects for this sort of thing, but one should try everything….

“If I were a physicist, I would study intellectual history to identify situations similar to the one we find ourselves in now.”

I have nothing against philosophy, but this idea that physics is going to be saved by some “simple, and in retrospect obvious” philosophical insight is just ridiculously naive. Physicists are well aware that progress may require radical new perspectives. However, progress also requires some understanding of how our current theories work and what sorts of extensions they admit. We’re not going to make progress by sitting around and trying to imagine ways in which the current situation might be similar to that one that existed in the time of Einstein.

“It strikes me as similar to the ill-fated effort to explain the geocentric orbits of the planets through ever more complicated mathematical systems of epicycles upon epicycles.”

You can always count on some layperson comparing string theory to epicycles on this blog, and it always exposes ignorance. One of the implications here is that string theory is some sort of ad hoc construction that can be modified in any possible way. On the contrary, many people are interested in string theory precisely because of its uniqueness properties. The comparison to epicycles also suggests that string theory might be abandoned some day. It should be obvious to any honest person with minimal knowledge of the subject that string theory is here to stay. Even if it doesn’t provide a successful theory of everything, it’s taught us a lot about how quantum gravity works conceptually, and it’s one of the main tools of theoretical physics.

Looking at history, its not philosophy that physics needs, but relevant experiments. Theoretical physics should go back to phenomena that can be observed in experiment. String theory and quantum gravity are of course attractive to mathematically inclined physicists, but these topics do not bring physics any further. Sad, but true.

@Martin:

I agree completely that what theoretical _particle_ physics needs right now is new data (and lots of it). However, I see nothing wrong with studying string theory and quantum gravity within the context of mathematical physics. We’ve learned a good bit about the mathematical structure of quantum field theories by doing this. For example, Seiberg & Witten’s demonstration of confinement in an interacting 4d QFT and Komargodski & Schwimmer’s proof of the a-theorem

Bob Jones and others are completely right that most people who study string theory are working on this sort of thing, not on the multiverse and similar sorts of nonsense. It’s unfortunate that we spend more time discussing this garbage than we do talking about real advances in scientific understanding. But what do you expect? Real advances in scientific understanding are rare and frequently difficult to understand, while nonsense is easily produced and easily discussed. What would you choose if your living depended on getting people’s attention?

(Question for Peter: Are you really doing the world a favor by bringing this stuff up all the time? I wouldn’t be surprised to learn that your blog probably has a wider readership than the many/most of the press releases and pop sci articles you find. Is it possible that you’re effectively feeding the trolls by covering this stuff?)

Bob Jones, in my judgment the comparison between string theory and epicycles is apt. Our disagreement about this is not due, it seems to me, to my “ignorance”; rather, I think that you are committing logical errors. That said, if it were due to my ignorance, I would likely not be aware of this fact; we all posses a degree of epistemic self-blindness. In the end, one of our positions will be vindicated, and one will not.

As an example of your logical error, we can accept both your criticisms and yet still maintain the insight that string theory is like epicycles in the relevant way. That is, the objection is not that string theory hasn’t been useful, or that it isn’t “here to stay”, as you put it, but that it appears to be the wrong *type* of theory. The argument runs as follows:

1) There have been numerous points p1 . . . pn in history (not including the current crisis) in which physics has found itself stymied, apparently unable to make progress.

2) For each of these p1 . . . pn there eventually was found a solution, s1 . . . sn, respectively.

3) Each of the s1 . . . sn share common traits T1 . . . Tm. Among these is that the key insight, what really made the solution possible, was a deeply conceptual, “philosophical” insight. None of the T1 . . . Tm is that the key insight, what really made the solution possible, was an increase in mathematical complexity and technical cleverness. (If there was an increase in mathematical complexity and cleverness, it did not enable the discovery but rather was a side-effect of it.)

4) String theory contains no deeply conceptual, “philosophical” insights. It does contain many increases in mathematical complexity and cleverness.

——-

5) String theory is unlikely to be correct.

That’s the argument, anyway. An intellectual historian could weigh in on the truth of the premises.

Another logical error that you commit, which string theorists commit frequently, is that you seem to think that all of us who disagree with you are stupider than you. That’s both a error in reasoning and factually false. You may well be smarter than me, but how smart can all these string theorists be if they keep committing simple, symbolic logic 101 errors in their reasoning?

LogicFan/Bob Jones,

Sorry this exchange has reached the point of zero worthwhile content, I’ll delete any attempts to pursue it further.

Epicycles shouldn’t be compared to string theory. Its degrading.

The ptolemiac model was one the the most succesful scierntific theories ever. It made predictions, there were observations and it even had practical uses.

AJ,

Actually, I’m regularly resisting writing about string theory related nonsense in pop sci articles. Just today there was

http://www.newscientist.com/article/mg21929342.800-supergoop-universe-offers-a-window-into-glassy-physics.html

which tells us that

“Welcome to the supergoop universe. This hypothetical reality derives from string theory, which allows for a large number of possible universes, each with different physical laws.”

which I have no intention of discussing.

The reason that the media is full of multiverse nonsense is not because of my blog, but because very prominent people in the physics community are aggressively pushing it. As long as this is going on, I think there needs to be someone pushing back and making clear the problems with this point of view. I don’t see anyone else doing this. By the way, are you calling Sean Carroll, Nima Arkani-Hamed, Savas Dimopoulos, Lenny Susskind, Andrei Linde, Steven Hawking and Frank Wilczek trolls?

I think we agree that some string-theory motivated research is good mathematical physics. The problem is that as long as people refuse to admit that parts of the string theory research program are a failure, there’s an associated failure to be able to distinguish between unpromising things whose motivation is a failed idea and more promising ideas.

* By the way, are you calling Sean Carroll, Nima Arkani-Hamed, Savas Dimopoulos, Lenny Susskind, Andrei Linde, Steven Hawking and Frank Wilczek trolls?*

If the shoe fits.. (Also, less than half of those people are string theorists. Perhaps it’s cosmologists you have a problem with? Or Palo Alto residents?)

As for the goop, that’s a classic example of gee-whiz pop-sci writing doing a discredit to an interesting scientific analysis. Interested parties should read the paper instead. No mention of the term ‘universe’, and the authors make it quite clear that they think the main use of these models is that they exhibit features analogous to those seen in real world condensed matter systems. Not much different from thinking about the Ising model as toy model for salad dressing.

There seem to be many different interpretations of what Turok actually said. But after I watched the actual video, it seems to me that he was asking for one thing every physicist would just love to have, but none do so far — a working theory with a smaller number of free parameters.

The Standard Model has 18-20 or so parameters (depending on how one counts), and creating a BSM theory which has a 120 or 10^500 free parameters is obviously not a step forward. What Turok was asking for is that we need to formulate a BSM model which *reduces* the number of free parameters in the SM. This can be done only by figuring out and formulating some deep principle that nature obeys, which would be powerful enough to establish relationships between existing parameters, thereby explaining some of them in terms of the others.

The only example of a model that even remotely comes close to this goal is the noncommutative SM developed by Alain Connes and his collaborators, which AFAIK features one extra equation relating the particle masses in the SM (IIRC, it has one free mass parameter less than the SM itself).

Also, we should all keep in mind that Turok was addressing very young freshmen students, so his words should be understood within that context. He was giving a lecture to students about what is important in hep-th research, and what it means to make a prediction — to cover as much as possible of the experimental data, with more concepts and less free parameters to be adjusted.

One of the most vital things that a hep-th researcher should know is to distinguish the physical concepts that nature satisfies from the mathematical formalism used to express those concepts. Students should be aware that we need new principles, rather than more complicated formalisms. The state of the art today is that formalisms are abound in hep-th, while concepts are very few and hard to come by. Turok is very right to call this a crisis.

And it’s not just about the lack of new experimental data, it’s also about lack of understanding of the already existing data. String theory has 10^500 parameters to fit the data, SUSY models have 120 or more parameters to fit the data, the SM apparently fits all data with just 18-20 parameters. The real challenge is to make a theory that will fit all data with *less* than 18 free parameters. Only *that* would constitute a real progress in understanding nature. Everything else is just formalism, bells and whistles, cosmetics, and free-parameter-fitting.

HTH, 🙂

Marko

hi marko, i do not insist on the counting, but only on the issue that we should respect the valid principles, and “gauge principle” is what i had and i have in mind, with my pedantic counting. i note that grand unified models are gauge theories, i.e., theoretical constructs based on valid ideas. their exploration cannot be said to be complete. the reason why they have been largely ignored in the last 10 years or so is the so called “naturalness principle”, that i do not think deserve as much respect as “gauge principle” (i know that other people disagree with me here). from the counting of turok, the grand unified theories do not deserve credit because they have “100 parameters”. i think this is a superficial statement, just as the counting of the sm parameters, without considering what the sm is: a well defined gauge theory. i think this kind of opinions can mislead freshmen students. with friendship 🙂

A.J. is right.

OT: Peter : any comments from any of the talks from the firewall conference

at KITP? I watched Bill Unruh and Bob Wald’s talks where they were critical of ADS/CFT

and they were met with some hostility from string theorists

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