This blog was started a little bit over ten years ago, and I’ve been intending for a while to write something marking the occasion and commenting on what has changed over the past ten years. I’ve found this mostly a rather discouraging topic to think about and whatever I have to say about it is going to be pretty repetitive for anyone who regularly reads this blog, so I’ll keep this fairly short.

Re-reading some of the early postings I’m struck mainly by how little has changed in ten years. Back in March 2004 I was writing about a David Gross talk promoting string theory, about whether CMB measurements would give information about GUT scale physics, about how string cosmology seemed to be an empty subject, and about new twistor-based methods for computing gauge theory amplitudes. There’s been a lot of progress on the last topic since then, but little change for the others.

One big change over the past ten years is that the argument that string-theory based unification is a failed project is no longer a particularly controversial one, with most physicists now leaning to this conclusion. Last night even Sheldon of The Big Bang Theory acknowledged that this isn’t working out and he needs to find something else to work on (see here). Maybe even Sheldon’s real life model will soon reach this conclusion. Ten years ago the argument one often heard was that string theory was the winner in the marketplace of ideas, with skeptics just sore losers. These days, it’s string theorists who are more often complaining about the unfairness of this marketplace.

One development that is just starting to have a major impact is the failure of the LHC to find any evidence of SUSY, leading to increased skepticism about SUSY extensions of the standard model. This is a developing story, with results over the next couple years from the LHC likely to make this a textbook example of what scientists do in the face of experimental disconfirmation of their most cherished ideas.

The discovery of the Higgs has been a wonderful vindication of the ideas and techniques of high energy physics, both experimental and theoretical. As we learn more about the Higgs the lesson seems to be that this sector of the Standard Model behaves in the simplest way possible. This is a significant new piece of information about nature, although a frustrating one since it doesn’t provide a hint of how to improve the Standard Model.

On the whole though, I fear that thinking about changes over the last ten years mostly puts me in a not very good mood. Some of the depressing developments and trends of the last ten years are:

- One reaction to string theory’s failures in the marketplace of ideas has been a Russian billionaire’s decision to try and manipulate that marketplace by injecting tens of millions of dollars into it on one side. The largest financial prize in science now is devoted to each year rewarding people for work on a failed project. This is corrupting the marketplace in a significant way.
- Some of my earliest postings back in 2004 were about KKLT, the string landscape and the multiverse. At the time I was sure that if the landscape proposal being pushed by the Stanford group became widely accepted as an implication of string theory unification, that would be the end of it. Surely no sensible person would try and argue for an extremely complicated, inherently unpredictive theoretical framework. Boy, was I wrong. As I’ve gone on about far too often here, the current multiverse mania is a disastrous and shameful episode for fundamental theoretical physics, threatening its essential nature as a science.
- Most physics departments have reacted to the failure of string theory by at least partly blaming this failure on the over-emphasis of mathematics, instead of the fact that this was just a wrong idea about physics. An interesting document I recently ran across is this one about the connections of particle physics with other disciplines, written by my advisor Curtis Callan and Shamit Kachru. Mathematics is mentioned in a section discussing past successes in cross-fertilization with other fields, but it appears not at all in the rest of the document discussing opportunities for the future.

I’m quite surprised that I’ve continued to find topics worth blogging about ten years down the road, this is something I never expected when this started. Right now I’m hoping for something unexpected in coming years, that I’ll be writing about something different and much more interesting ten years from now!

Oh no! Hermione Granger doesn’t actually exist!

http://www.aps.org/publications/apsnews/200808/zero-gravity.cfm

Thank you for maintaining your blog for these past 10 years, most of which time I have been looking at it just about every day.

I’ve learned at lot, but the main thing I’ve learned is the unsettling news that, when science gets stuck, or harder, a lot of scientists kind of give up and start doing metaphysics. Unfortunately they don’t seem to want to admit that’s what they’re doing.

I have nothing at all against metaphysics, quite the contrary in fact, but I would like to be able to keep my science and my philosophy separated by the criterion of empirical testing.

I would be very interested in any suggestions about how young scientists might better be educated to avoid this trap without losing their curiosity and drive to understand.

Regards,

Mike Gogins

The attitude that the failings of string theory are due to “too much mathematics” is just insulting to mathematicians.

It may be that string theory was not good physics. That does not mean that the bits of string theory that pretended to be good physics, were good mathematics.

Lets be clear : to a large extent, it is valid to see the problem of quantum gravity to be a mathematical problem.

Giving a single theory, with a reasonable degree of mathematical rigour, that reduces to the SM and GR in appropriate limits, would be a huge advance, whether or not that theory actually turned to describe our universe.

From that point of view, testability of a theory-of-everything is actually a red-herring – the experiments have already been done: the ones that confirm GR and the ones that confirm the SM. The problem is to find any respectably rigorous ToE that gives correct calculations of the outcomes of all those experiments. Currently it appears to be mathematical rigour that is lacking.

Of course, once we have a ToE that makes mathematical sense, the questions will be “how do we test it” and “how do we experimentally distinguish it from alternatives”. I am not claiming that experimental testability is unnecessary, it is just that we appear to be as far from having a real theory to test, as we are from actually probing the planck scale directly.

I was hoping for dialog like this.

Penny: What is string theory?

Sheldon: That is the idea that all mysteries can be explained by saying that everything is a string in 6 extra dimensions.

Penny: I could have told you that is a dumb idea.

Peter, congrats on a remarkable 10 years of blogging! You’ve been not just the main source documenting ST irrationality, but also this blog has become a great site for all particle physics news.

” Sheldon’s real life model “. ho would that be?

Keep up the great work! I certainly enjoy reading you blog each week.

Yes, thanks for the blog, it’s always informative and I think you’ve been quite brave.

Coincidentally, we are at a quite significant moment – as many string theorists are

anxiouslyawaiting to see if there will be corroboration of the BICEP2 result. Mysteriously there has not been much comment that the result r~O(0.1)destroysnearly all string inspired cosmology models. Yeah yeah – string gas cosmology and axion monodromy are suddenly the new stars – but there were bound to be some string inspired ideas that still survive, since the theory “predicts” almost everything!Great past decade! I’m certain you’ll be writing about interesting new physics soon…

Congrats on the 10 years of blogging, and just as they yell at the political conventions “four more years, four more years”, with the same spirit I write “ten more years, ten more years”!

Peter,

“There’s been a lot of progress on the last topic since then, but little change for the others.”

Aren’t you a bit pessimistic ? On the second topic (CMB and GUT) it seems that something rather big may have just happened. So: progress on twistor, discovery of the Higgs, and maybe indication that inflation occurs at GUT scale… this is not so bad for ten years in theoretical physics, I would say.

Martibal,

Discovery of the Higgs is a great experimental triumph, unfortunately not a recent advance in theoretical physics. I don’t yet see that CMB results tell us anything signficant about GUT scale physics, maybe some day, but not yet. Amplitudes are about it…

Why no mention of BICEP2 results here? I would argue that that changes a bit of the first points you mentions. As JG rightly points out, if the results are corroborated, it falsifies a lot of cosmological models, among them a lot of string based ones. So then clearly the assumption that string cosmology is “empty” is just wrong: the string models are just as falsifiable as the “normal” ones. And the idea that CMB observations can tell us something about quantum gravity is looking promising as well. For one thing, it gives us the energy scale of inflation, that alone is some very interesting information about GUT/BSM physics.

Well done on the 10 years + book Have been following the blog since the book and, even as someone with very little physics knowledge (but much interest in the general topic), this is one of the most consistently good blogs on any topic I read about.

I’d be interested to know how many real world Sheldons there are–bright young physicists wondering if they have spent their most creative and productive years on what looks like a dead end?

What, no mention of all the excellent rumor-mongering?

hopffiber,

Yes, lots of “string cosmology models” may have been falsified, but what has not been falsified is the claim that you can get just about anything at all out of some complicated “string cosmology model”, so “string cosmology” isn’t science in the usual sense.

As for the CMB telling us something significant about quantum gravity and about GUT physics, that’s not inconceivable but I don’t think we’re there yet, whatever you read in the papers…

We have to keep in mind that the BICEP2 results may very well turn out to be “wrong”. They have no doubt measured something and have found it to be equal to 0.2 but what is it that thing? Background noise? Magnetized dust from supernovae? Following good academic traditions we have to wait before shouting hurrah.

The most striking message from LHC is that the naturalness arguments presented so far are not valid. Nature seems to have a different line of reasoning. This reminds one of the naturalness arguments for why the neutrino mass had to be zero. After all it was advocated by no less than four Nobel Laureates. Nonetheless it turned out to be wrong.

Peter

Thank you for defending the scientific method for the past ten years!

Yes we now recognize that String theory has conceptual problems. My question is can the same be said about Loop Quantum Gravity?

First: congratulations. I think your post plays an important role. I have always had this conviction that you can only really beat an idea by providing a better one. I think ST will eventually fade away, but it might not happen until someone gives a strong alternative. The problem is perhaps that the present setup of theoretical physics might be somewhat opaque to new ideas.

About this “over-emphasis of mathematics” on the ST side. My own experience is the complete opposite, that is, a lack of emphasis on mathematics. A couple of years ago I gave a talk with a couple of very prominent ST physicists in the audience. After my first slide I was asked – again, by a very prominent ST-guy – what a C^*-algebra is…

@ Stuart: yes, the same can be said about LQG, but of course, the problems there are of a different nature (and most likely OT).

Peter, there has been a lot of progress in experimental neutrino physics in last 10 years including evidence for non-0 theta_13. However its still not clear to me what exactly non-0 neutrino mass and mixing tells us about rest of particle physics and

beyond standard model theories.

Who’d have thought 10 years ago that blogs would still exist today? Your blog is one of the few that I follow, so I am looking forward to the next decades

Got the book, read the blog; not got the T-shirt yet. Congrats Peter. A lot of hard but necessary work. Anthropologists in the far future will find blogs like this a gold mine. Your predictions for the next 10 years please.

Congrats on passing the 10 yr blogging milestone! Your book was an eye-opener for this layperson, and your blog is a v nice portal into today’s math and physics happenings. I hope you continue…

This seems like an appropriate entry to ask the question whether there is any sort of posting, article, or book summarizing these disputes over string theory, falsifiability, etc. appropriate for the layman. Any leads would be appreciated. (I hope I’m not overlooking an obvious answer to this posted on the site, but I didn’t see it.)

CThomas

@Woit: sure, that claim of yours is true to some extent, but how is it different from “normal” model building, in cosmology and elsewhere? You can also get almost anything from complicated constructions using just ordinary QFT (or LQG, I suppose). String theory does add some more possibilities since its more complicated, but I don’t see any real reason besides pure anti-string bias to single out “string cosmology” as particularly empty compared to other approaches. And as long as you can test your models against new data and falsify them, isn’t precisely science in the usual sense, or how do you define “usual science”?

And as for the second part, yes, we are not there yet. But it is quite promising and could very well give us quite a bit of interesting information about the scale of GUT and inflation. So I think stating that “very little happened in 10 years” is way to pessimistic, overall.

CThomas,

I’ve written a book about this (also called Not Even Wrong), and if you read that and one of the books from a string theorist (Brian Greene’s The Elegant Universe would be a good choice), you’d get both sides. Both of these books are a bit old now, but, not much has changed. Also, on this side there’s a FAQ

http://www.math.columbia.edu/~woit/wordpress/?page_id=4338

hopffiber,

http://www.math.columbia.edu/~woit/wordpress/?wp_super_faq=isnt-string-theory-just-as-predictive-as-quantum-field-theory

Dear Peter

Congrats on 10 years of doing exactly what science is supposed to be: open honest debate about the current issues. Whether you are correct or not really doesn’t even matter. It is that you have provided an outstanding example of the process of refining ideas. In addition to this, your lively and slightly cynical style makes for great reading, entertainment, and the occasional “OMG, I don’t believe he said that out loud!” Political correctness is the bane of peer review, and you set a great example of how to do it the right way. Not with trivialities, but by going right to the heart of the matters and focusing on core questions.

Thanks a million and I for one look forward to many more years of your posts.

Best wishes to you, Sir,

Don

There’s simply nothing wrong with string theory. The vast majority of string theorists are mediocre and not up to the task. A tiny minority of string theorists actually do something useful and every five to ten years make significant progress. This is a ‘Theory of Everything’, after all and the only one that really works but it cannot be expected to resolve itself in the same manner as other scientific theories in the past. String theory is its own game and it has produced more losers than winners. Many were called but few were chosen. What did they expect anyway? Doesn’t nature operate this way? It’s time for the Sheldons of string theory to move on and make room for the new guard. Believe wholeheartedly in the power of young people. Somewhere, some young person is going to take the next step, bring us to a better level of understanding physics and string theory than ever before. I’m their biggest fan already.

Got your book on 4/5/14 and finished it today. I do have a question about it. In the chapter “The only game in town” you mention the average age of tenured professors in 1970 as under 40, and that the latest figures (circa 2000 according to footnote 12) were for an average of nearly 60 for tenured professors. My question is, has that changed any since your book was published? Anyway, congradulations on ten years of good blogging.

Thanks to all for the kind words and encouragement.

Jim Akerlund,

I haven’t seen more recent numbers (but haven’t looked), would be interested if anyone has any. I’d guess the average age number has stabilized (or even started to go down), as the cohort hired in the late 1960s has started to retire post-2000. Retirements by themselves should bring the number down, retirement + replacement by new hire even more so.

Jason,

That the “vast majority of string theorists” are just too stupid is an original explanation for the problems of string theory. I hadn’t heard that one before and I thought I had heard them all.

Jesper,

Really, a physicist didn’t know what a C* algebra is? Really? I mean I’m a mathematician, but I’m pretty sure I first learned about C* algebras when I took QM (a VERY long time ago

Did you ask him if he knew what a Hilbert space is?

Sorry, I assumed it was a him, my bad, there are some prominent female string theorists…

Peter,

Thanks for the ten years and keep up your good work.

For some of us this is the site that knocks some sense into news items and weeding out new books on physics – saving us time and disappointment with the hype.

Eddie

Jeff M/Jesper,

I don’t think there’s anything at all remarkable about not knowing what a C* algebra is, wouldn’t surprise me it most mathematicians don’t know this either. You can understand QM quite deeply without the operator algebra/functional analysis perspective, and you can understand the statements relating QM and C* algebras without understanding anything significant about QM at all. So many different sorts of mathematical technologies have been tried out in string theory that surely no one understands them all.

Physicists rarely learn mathematics from the ground up, from general theory, more often from how mathematics gets used in a specific example they work with. This isn’t at all a bad thing.

may jason is being sarcastic. though witten et al did say to paraphrase string theory is smarter than us.

maybe string theory is the correct description of nature but humans are not intelligent enough to understand it.

QG,

For any scientific idea that doesn’t work out, you can try and argue that it really is fixable and will work, but we’re too stupid to know how. While this could always be true, there’s a good reason this is not the conventional scientific method.

CThomas: You might be interested in http://gilkalai.wordpress.com/2009/06/23/my-book-gina-says-adventures-in-the-blogsphere-string-war/

Peter,

Actually I would be much more surprised by physicists not knowing C* algebras than mathematicians, I only know about them really because I was originally a physics major. In math you would only know much about them if you work in some related field, though probably you would have seen them around. I just can’t believe anyone took a real QM course where they weren’t mentioned.

As for how physicists learn math, I think you’re right but I do see issues with that, since it makes it much easier for them to ignore the required rigor and claim they’ve “proved” something when they haven’t even come close. Whats the joke, “If you understand something and can prove it, publish it in a math journal, if you understand something but can’t prove it publish it in a physics journal…”

Hi Peter,

Congratulations on ten years of blogging! I recently came across your blog and I always find your posts entertaining. I hope to read your book someday.

I’m sorry if this is off-topic, but I thought I’d ask an expert – does the recent discovery of exotic hadrons at CERN have significant implications for HEP? I thought the reaction seemed a bit muted. Is it fully consistent with the Standard Model?

Goosebumps,

Thanks!

The existence of these exotic hadrons is as far as we know consistent with QCD and the Standard Model. One of the big problems in theoretical physics is that there’s a lot we don’t understand about QCD, because of the lack of good calculational methods. So, we don’t know exactly what the theory predicts for such states. Better understanding QCD is a problem that deserves more attention than it gets, but it’s extremely difficult, and people have been working at it for about 40 years with only limited successes.

Congratulation, Peter . I have learned alot from following your blog. But I do think there are many reasons to rejoice about progress !

I am surprised that you do not include the ADCFT correspondence and its applications in solid state, quark-gluon plasma and quantum entanglement as a remarkable area of progress . The holographic principle will most likely lead to new understanding of quantum mechanics at it deepest level. While field theorists have been accustomed to remarkable successes from the days of quantum electrodynamics, most deep problems are understood over longer periods of time with many failures. The theory of evolution is almost universally accepted,however there are in fact many ways in which its initial formulation is flawed and our understanding continues to evolve. Evolution needs to be defended against the no-nothings who attack science, it also needs to be criticized and to be developed with our increasing understanding of ideas like epigenetics, which looks closer to the ideas of Lamarck than Darwin.

We do not know as yet whether string theory will survive as a fundamental theory, but of it does not, many of the ideas will surely survive in the transition to the next stage .

@JeffM,

I took a graduate quantum mechanics course from Ed Witten, and C^* algebras weren’t mentioned…

@Peter,

Congratulations, and many thanks for the great blogging for 10 years… I read it avidly, and share lots of the posts with colleagues who are ‘former QFT’ers.’

@Bernard Grossman

I find the comparison to evolution to be flawed. We biologist have 150 years worth of both historic and experimental data to use for developing the evolutionary theory. If anything,at the moment biologist have exactly opposite problem, thanks to genomics/proteonomics/whatever-omics. So much emperical data and not enough tools to make proper use of it.

Things are quite different for string theorist in this regard. Apples, oranges and so on.

About the C*-algebra stuff: perhaps I should elaborate a little. The ST-guy, who asked me what a C*-algebra is, was in the early 2000’s involved in the “noncommutative geometry-meets-ST” surge. Thats actually the reason that it surprised me so much that he apparently wasn’t aware of the concept of a C*-algebra. After all, he had been publishing numerous papers in a field very closely and somewhat overlapping the work of Connes (and without any doubt, had been attending conferences where Connes or someone else from NCG was speaking). Thus, for him not to know what a C*-algebra is meant to me that he hadn’t bothered looking at the math so closely related to what he was doing. Since he is a leading figure in the field ST I sort of took it as an indicator.

This is just to comment on the mentioned ‘over-emphasis on math’ and for me, its just one illustration of something, which I have noticed over the years: that the ST people, whom I have been in contact with, certainly are not putting a lot of emphasis on math (I mean math, not computation). This may not be a bad thing (I tend to think it is) but the issue was simply the emphasis/not-emphasis.

While the analogy between evolution and string theory is not perfect, I would say there are lessons of hope and inspiration to be learned from the comparison . The theory of evolution as a theory strictly of genetics is flawed, but survives as modified by new developments and genetics is firmly based in our thinking about biology. We do not know whether string theory is flawed or just incomplete , but our understanding of the importance of spin two field theory, gravity and the renormalization group for many areas of physics has become deeper compared to the ideas before string theory of quantum gravity as a hopelessly nonrenormalizable theory .

Thanks for a regular dose of thoughtful blogging.

Jeff M

Just like in the early days, when most physicists learnt QM from Dirac’s textbook, not Von Neumann’s (which wasn’t even translated into english until the 1955), modern physicists are not always concerned with mathematical rigour. Any course in QM which attempts to discuss it in full mathematical rigour is pretty tedious to most tastes, and you must admit that not many breakthroughs in physics have been made by the use of mathematical rigour. It annoys me, for example, when people criticise Einstein’s quite messy route to GR compared to Hilbert’s apparently pristine derivation – yeah AFTER he’d got the crucial ingredients from Einstein! Or people who praise so highly Born and Jordan’s rigorous rewrite of Heisenberg’s crucial insights (he had not even heard of matrices at the time) – as if the mathematically rigourous formulation was the great achievement here (Dirac independently derived most of the same stuff in a few weeks, also AFTER reading about Heisenberg’s crucial insight)

btw for a discussion of Dirac v Von Neumann approach see here

All,

In general I’m all in favor of discussion of math and QM, but it is pretty much off-topic here, best would be to postpone this until it is on-topic. This should happen sooner or later, since I’m still working on the last chapters of the book I’m writing on this and when I finish a first draft I’ll write about this here. This fall semester I’ll again be teaching a course on this topic, so also likely will want to blog about this topic then.

Peter – Thank you for writing this blog for these ten years! Hope to read what the next ten years of NEW will bring.