Peter Woit's Blog: Good Stuff, Not Too Hard on String Theory

[selfAdjoint]

Peter Woit has a blog! . Much good stuff, not too hard on string theory, plus check out his links.

 

[marcus]

Originally posted by selfAdjoint
Peter Woit has a blog! . Much good stuff, not too hard on string theory, plus check out his links.

Fascinating. Very interested by his summary of the points in
David Gross talk.

will check out his links after lunch.

 

[selfAdjoint]

Note that in his post "The Holy Grail of Physics" Woit mentions Jackiw. Jackiw has a retrospective paper, http://arxiv.org/abs/physics/0403109 for the 50th anniversay of Yang-Mills, in which he discusses the helicity puzzles that Woit speaks of.

 

[marcus]

some gems from Woit's blog

Woit's March 19, 2004 blog was especially informative. As senior faculty at Columbia, in mathematical physics---the guy teaching grad students their QFT and Representation Theory---his judgements on the past 20 years progress in Particle Physics are especially crisp and authoritative.

--------Woit's comment on David Gross talk----
Gross's talk contained the usual tendentious pro-string theory points, here's a few of them with commentary:

1. " String theory is in a period like that of 1913-1925, it's like the Bohr model, we're waiting for the analog of Heisenberg's or Schrodinger's breakthroughs"

The problem with this is that the Bohr model was actually predictive, for instance it predicted a lot about atomic spectra that could be experimentally checked. There clearly was something right about the Bohr model, there is no good evidence there is something right about string theory.
...
...
4. "String theory is a consistent, finite quantum theory of gravity"

Simply not true. Peturbative string theory is a divergent expansion, non-perturbative definitions don't work for four large flat dimensions, rest small.

5. "String theory inspired brane-world scenarios, although I don't really believe these"

Why would you think that an argument in a theory's favor was that it inspired some clearly wrong models that you don't believe and that don't predict anything?

--------end quote-------

 

[jeff]

Originally posted by marcus
As senior faculty at Columbia...his judgements on the past 20 years progress in Particle Physics are especially crisp and authoritative.

Peter woit is just an instructor, not a professor. If you search the arXiv's, you'll find two papers by him, with one of them being a five page polemic on string theory in the subject class of 'physics and society' and with not a single reference. If you want to learn about string theory, this isn't the place to start.

 

[marcus]

So we have on good authority that string theory is not
a viable quantum theory of gravity.

Since it has been hugely hyped as exactly that, it's time for major debunking.

----at the end of Woit's March 19 report on Gross talk------

...I noticed that two string theory postdocs I know were in the audience. They've both told me that they think the subject is at a point of crisis and they are thinking of quitting. I don't think anything Gross said was likely to encourage them to continue.
-----------end quote---------

 

[marcus]

I may be mistaken about Woit's standing in the math and physics departments at Columbia. I am remembering from some months back when I happened to visit his website and saw the graduate level courses he was teaching.

Would be glad for fuller information. In which department? Mathematics or Physics?

Answered my own question!
The math department at Columbia has this link
http://www.math.columbia.edu/people/faculty.phtml

It shows that Peter Woit got his PhD in 1985 from Princeton.

So he was probably born around 1960 and must be in his Forties.

In some sense senior---I would guess tenured faculty. No doubt we will learn more.

 

[Haelfix]

Woit is a smart guy, I've met him before. He's echoing publically what we often hear in private conversations with mathematicians, who work on physics.

Theres a huge literature that is often overlooked by physicists, (aside from a select few like Witten) that deals with QFT/string theory etc using modern approaches and topics that are just recently becoming rigorous in mathematics.

Advances in K theory, infinite dimensional lie groups, etc etc

The fact of the matter is, its perfectly normal to expect skepticism from mathematicians, since the tools to treat String theory in a manner that makes sense to them doesn't exist yet. Its no coincidence physicists say its a 21st century theory that happened to be stumbled upon in the 20th century.

AFAICS, Woit's main beef is that the lvl of funding is so lopsided and other lines of inquiry seem to be supressed monetarily in favor of the orthodoxy.

 

[marcus]

Originally posted by jeff
Peter woit is just an instructor, not a professor. If you search the arXiv's, you'll find two papers by him, with one of them being a five page polemic on string theory in the subject class of 'physics and society' and with not a single reference. If you want to learn about string theory, this isn't the place to start.

have to see about whether a professor or instructor
instructor was usually a title for young faculty
not yet on tenure track. I suspect that Columbia math dept
has no instructors on the faculty---full-time positions
would most likely be all assoc. prof. or asst. prof. or full professor. But you could be right! No doubt we will see in time.

 

[marcus]

Originally posted by Haelfix
Woit is a smart guy, I've met him before...

Haelfix do you happen to know if Woit has made professor.
We have someone here saying he is "just an instructor" which
would seem bizarre given the other signs of senior faculty standing.

 

[rick1138]

Here is a link to Gross's talk:

http://online.kitp.ucsb.edu/online/mt01teach/gross/

 

[lethe]

Originally posted by marcus
Haelfix do you happen to know if Woit has made professor.
We have someone here saying he is "just an instructor" which
would seem bizarre given the other signs of senior faculty standing.

which "other signs" were you talking about? the fact that he teaches classes? i know lots of people who teach, and yet are not professors.

anyway, you can see from the math department website that he is a "Director of Instruction", and not a Professor (associate or otherwise)

i guess you just chose not to see that when you were looking at it.

 

[Haelfix]

No clue what position he holds, other than that he works at Columbia, not that it matters.

I do know that he knows what he's talking about w.r.t to field theory. But I don't think he is an expert on String theory, there are others at Columbia that know a lot more about that sort of stuff. Phong, Greene et al.

Typically mathematicians are introduced to String theory, when a physicist wanders over to their department when they're confused about something and nead expertise in some archaic form. The mathematician then has the distinct horror of trying to figure out a problem, without even knowing where its coming from.

The conversation will go something like
Mathematician 'whats that measure'
Physicist 'its undefined'
Mathematician 'what?!?'
Physicist 'ignore it, just tell me what Hodge theory says about this right here'
...

I exagerate, but that's often how things can go. The physicist will go off pleased, and the math guy left wondering about their sanity.

 

[selfAdjoint]

Originally posted by marcus
have to see about whether a professor or instructor
instructor was usually a title for young faculty
not yet on tenure track. I suspect that Columbia math dept
has no instructors on the faculty---full-time positions
would most likely be all assoc. prof. or asst. prof. or full professor. But you could be right! No doubt we will see in time.

The university site has him as "Director of Instruction", which is surely not the same as "Instructor"? And he is the only individual included on that site who is not listed as some kind of Professor.

 

[marcus]

not to confuse Director of Instr (admin position some places comparable to Associate Dean) with Instructor (pre-tenure-track grade for young hires) for example
Greg Miller at U Washington
got his Phd in 1983
became Assistant Professor 1984
Associate Professor 1988
Professor 1995
made Director of Instruction 1998

be patient, more will probably come out about Woit's standing
he is a very interesting person
he watches theoretical physics closely
and at Columbia he teaches the graduate level courses in
Lie Groups and Representations
Quantum Field Theory
he has ideas about what direction EXPERIMENTAL hep should take
he is not exactly Haelfix's model of a periferal mathematician
shaking his head in disbelief at the vagaries of physicists
he strikes me more as a centrally knowledgeable type of math/physicist.

in any case I do not accept the dismissive estimate that Woit is "just an instructor" and I am happy to wait and learn more about this very interesting person

I do not know that he is a professor or not a professor and I am not convinced that this matters, but he seems senior to me---resepected, with some adminstrative function in the department---in his 40s---very smart----with a sense of history and a complex perspective

 

[marcus]

Originally posted by Haelfix
Woit is a smart guy, I've met him before.
...
AFAICS, Woit's main beef is that the lvl of funding is so lopsided and other lines of inquiry seem to be supressed monetarily in favor of the orthodoxy.

Haelfix I really like your sketch of the encounter between the mathematician and physicist. It is majorly true to life.
But I think Woit's beef is more interesting than that.

An important part of it is that the mathematics of string theory is not very interesting (or forward-looking) mathematics
and he points to more interesting directions in math/physics
where theoreticians could be going if they were not so
bogged in string

he is highly critical of the bromide about "a bit of 21st century that happened to plop down prematurely in the 20th century" or whatever Witten's inspired prophesy was

You have got me interested now. So I will go back to Woit's essay and see better what his beef is
I know it is about more than lopsided money, but I want to be refreshed as to details.

 

[jeff]

Originally posted by Haelfix
No clue what position he holds, other than that he works at Columbia, not that it matters.

I think it does matter since

(1) It's his ideas that are the subject of this thread.

(2) These ideas are by his own admission polemical.

(3) Marcus is trying to convince members that woit is more credible and more of an authority than he actually is.

Originally posted by Haelfix
But I don't think he is an expert on String theory

Correct. So how seriously should woit be taken? Well, he isn't a researcher, as is clear from the absence on his homepage of any mention of, or links to any research papers. And notice, as I already mentioned, that even woit himself refers to his paper criticizing string theory as a polemic, which means that he himself wouldn't counsel anyone to take his paper - which by the way is listed under the subject class of 'physics and society' and not 'high energy theory' where research papers on strings are listed - as seriously as marcus does (especially since marcus is unable to understand physics at this level, as he's shown repeatedly. In greg's words, "marcus isn't very smart".)

Anyway, given that woit got his PhD in 1985, we can say that after 20 years he ended up as head TA.

 

[jeff]

Originally posted by marcus
An important part of it is that the mathematics of string theory is not very interesting (or forward-looking)

This isn't just you being mistaken marcus, this is you knowingly misrepresenting the facts, which from what I understand violates site guidelines.

 

[notevenwrong]

Wow, a whole internet thread about my academic qualifications!

I'd certainly prefer that people spend their time arguing over what I have to say than my qualifications for saying it, but here's an accurate outline of my peculiar academic career for those interested:

1979: B.A. and M.A. in physics, Harvard University. As an undergraduate spent one summer working on a particle physics experiment at SLAC.

1984: Ph. D. in theoretical physics, Princeton University, advisor Curtis Callan, thesis title "Topological Charge in Lattice Gauge Theory".

In my thesis I developed a workable way of calculating the topological charge of lattice gauge fields. This lead to joint work with collaborators including N. Seiberg at the Institute in Princeton and about seven published papers on the subject in the mid to late-eighties.

1984-87 Postdoc at the Stony Brook ITP
Got interested in spinor geometry,TQFT and representation theory, started talking to a lot of the mathematicians at Stony Brook

In 1987 it became clear to me that someone who didn't believe in string theory but wanted to apply mathematics to QFT didn't have much of a future in physics depts in the US. I spent 1987-88 as an unpaid visitor at the Harvard physics dept., earning a living teaching calculus in the Tufts math department.

1988-89 Postdoctoral fellowship at MSRI in Berkeley. Published a couple papers on spinor geometry and the standard model, TQFT and representation theory.

1989-1993 Assistant professor, math department, Columbia

At this point the "Director of Instruction" position became available in the math department. It is an unusual untenured but permanent position, with responsibilities that include making sure the dept computer system runs, teaching a course, participating in research activities of the department.. I've held that position for ten years.

I'm not a tenured full professor at Columbia and have never claimed to be. On the other hand, I've spent a lot of time learning mathematics, often by teaching it. I've taught many of our undergraduate courses and some of our graduate courses, including Representation theory and QFT for mathematicians.

So that's my weird academic background and status. make of it what you will.

My experience arguing with string theorists over the last few years has been that the ones that don't know me often spend their time refusing to respond to my arguments and personally attacking me instead. I'll let you decide what that says about how strong their case is.

 

[rick1138]

Exactly. Stick to the matter at hand. Truth or falsehood is independent of its vessel. It is logically fallacious to suggest otherwise.

 

[Urs]

Hi Peter Woit -

one question:

Did I understand you correctly that you reject the Matrix Models of string theory as a viable nonperturbative definition for the reason that they, as I think you said, don't give four large dimensions only?

I think I have read that somewhere on your weblog.

Could you provide more details on this argument? Do you claim that there are in principle no solutions of the MM that are realistic, or just that so far none have been found?

Have you looked at the papers which describe the search for a spontaneous compactification to d=4 in the IKKT model? There have apparently been several numerical computations, which kind of point in the right direction but are not conclusive yet, either way.

Thanks,
Urs

P.S.
Would you think that I am just another impolite graduate student if I said that you are notevenwrong? ;-)

Just kidding! :-) But more seriously: Why that particular pseudonym??

 

[pelastration]

Originally posted by notevenwrong
Wow, a whole internet thread about my academic qualifications!

...

So that's my weird academic background and status. make of it what you will.

My experience arguing with string theorists over the last few years has been that the ones that don't know me often spend their time refusing to respond to my arguments and personally attacking me instead. I'll let you decide what that says about how strong their case is.

Thanks Peter for clarification. It seems that for some posters here a title is the most important parameter for the IQ-level. ;-)

 

[jeff]

Hi Peter,

Originally posted by notevenwrong
...here's an accurate outline of my...academic career:

1979: B.A. and M.A. in physics, Harvard University. As an undergraduate spent one summer working on a particle physics experiment at SLAC.

1984: Ph. D. in theoretical physics, Princeton University, advisor Curtis Callan, thesis title "Topological Charge in Lattice Gauge Theory".

In my thesis I developed a workable way of calculating the topological charge of lattice gauge fields. This lead to joint work with collaborators including N. Seiberg at the Institute in Princeton and about seven published papers on the subject in the mid to late-eighties.

1984-87 Postdoc at the Stony Brook ITP
Got interested in spinor geometry,TQFT and representation theory, started talking to a lot of the mathematicians at Stony Brook

In 1987 it became clear to me that someone who didn't believe in string theory but wanted to apply mathematics to QFT didn't have much of a future in physics depts in the US. I spent 1987-88 as an unpaid visitor at the Harvard physics dept., earning a living teaching calculus in the Tufts math department.

1988-89 Postdoctoral fellowship at MSRI in Berkeley. Published a couple papers on spinor geometry and the standard model, TQFT and representation theory.

1989-1993 Assistant professor, math department, Columbia

At this point the "Director of Instruction" position became available in the math department. It is an unusual untenured but permanent position, with responsibilities that include making sure the dept computer system runs, teaching a course, participating in research activities of the department.. I've held that position for ten years...

Would you mind offering some advice on how to approach your polemic on string theory to people who campaign against stringy research without even attempting to understand it's basic ideas (or even those of QFT, as is true for some people here at PF)? It might even help if you could say something about what you feel the purpose of polemical writing is in general. Thanks.

 

[notevenwrong]

Originally posted by Urs
[B
Did I understand you correctly that you reject the Matrix Models of string theory as a viable nonperturbative definition for the reason that they, as I think you said, don't give four large dimensions only?

I think I have read that somewhere on your weblog.

Could you provide more details on this argument? Do you claim that there are in principle no solutions of the MM that are realistic, or just that so far none have been found?

Have you looked at the papers which describe the search for a spontaneous compactification to d=4 in the IKKT model? There have apparently been several numerical computations, which kind of point in the right direction but are not conclusive yet, either way.

Just kidding! :-) But more seriously: Why that particular pseudonym?? [/B]

Hi Urs,
I'm no expert on Matrix models, what I know about their status comes from reading review papers and arguing with Lubos Motl.
My understanding is that Matrix models conjecturally provide a non-perturbative definition of string theory, but only in flat eleven dimensional space or some other special backgrounds. As far as I know, no one knows how to properly formulate a version of the matrix model that works in the kind of background you want (four large flat dimensions times a small, highly curved 6/7 dimensional Calabi-Yau or G2 holonomy manifold). This is what I was referring to in the weblog.

As for "Not Even Wrong", it was Pauli's description of theories so badly understood and ill-defined that you can't even tell whether they are right or wrong. This applies both to string theory and to the non-string theory ideas I've been thinking about. I wanted to write about both in the weblog, have much greater hopes for the latter than the former.

Peter

 

[rick1138]

notevenwrong,

What is your opinion of Nambu's interpretation of the dual resonance model. Do you consider this to be example of a physical prediction made by string theory? If not why not?

 

[notevenwrong]

Originally posted by jeff
Hi Peter,



Would you mind offering some advice on how to approach your polemic on string theory to people who campaign against stringy research without even attempting to understand it's basic ideas (or even those of QFT, as is true for some people here at PF)? It might even help if you could say something about what you feel the purpose of polemical writing is in general. Thanks.

The thing I wrote a few years ago and my public criticisms of string theory have a definite purpose. I think the way string theory has come to so heavily dominate particle theory is unhealthy in the extreme. Some of my writing is "polemical" in the sense that it tries to counter the extensive unbalanced hype about string theory with a an exposition of the arguments against string theory, not necessarily balanced by trying to include every good thing I can think of about string theory. I hope that this will get people to understand that the arguments for string theory are nowhere near as strong as they are generally made out to be.

My writing is most directly aimed at those working in the field, hoping to get them to stop and think about what is going on, whether or not I might be right that the situation has gotten very unhealthy, and if so, what can be done about it.

As for others, I encourage people who are just learning this stuff to spend a lot of time learning QFT and some time learning string theory. Much of string theory is really 2d QFT, which is a fantastic subject.

More and more I've become convinced that a large part of the problem with string theory is that it has become a huge, very intricate and difficult business. Most physicists don't understand it very well so are reluctant to criticize it. Others end up getting sucked into the huge set of questions that such a complex thing leads to and never get out.

I'm not going to spend my time worrying about the large number of people who don't know what they are talking about who criticize string theory, there are plenty of these, but at least as many who sing its glories. What I'd like to do is to make sure people have access to both the arguments for and against string theory. They then need to make up their minds what to spend their time learning and working on.

 

[Urs]

Concerning Matrix Models, since they are non-perturbative, there is no need to pick any background. They pick their own solutions. That's what the papers that I was referring to tried to compute, namely the (maybe unique?) solution of the IKKT model. Of course it hasn't been done yet, obviously, but the fact that the IKKT model for one is conceptually exteremely simple and, for finite size N of the matrices, effectively calculable. You should endorse that, because if it turns out that the unique solution to IKKT is not phenomenologically realistic, then that's it.

On the other hand, I would find it hard not to be fascinated by a working theory of quantum gravity in any number of dimensions > 3. That's what I find so hard to understand about the criticism of string theory. If nothing else, there is lots of theoretical insight in string theory. If it really describes our world is a completely different issue. Lots of field theories are also studied only for theoretical reasons, having nothing directly to do with the real world. I don't want to wait for the unique prediction of my telephone number until I consider to find progress in quantum gravity interesting.

 

[Haelfix]

'You should endorse that, because if it turns out that the unique solution to IKKT is not phenomenologically realistic, then that's it. '

Urs can you expand on this a little, I am rather curious by what you mean.

Assuming no realistic solution is found, would it outright falsify any 11 dimensional model without compactified dimensions based on Stringy mechanics?

Or is there enough subtleties to either argue it away, or criticize the validity of the actual model itself?

 

[notevenwrong]

Concerning Matrix Models, since they are non-perturbative, there is no need to pick any background. They pick their own solutions. That's what the papers that I was referring to tried to compute, namely the (maybe unique?) solution of the IKKT model. Of course it hasn't been done yet, obviously, but the fact that the IKKT model for one is conceptually exteremely simple and, for finite size N of the matrices, effectively calculable. You should endorse that, because if it turns out that the unique solution to IKKT is not phenomenologically realistic, then that's it.

On the other hand, I would find it hard not to be fascinated by a working theory of quantum gravity in any number of dimensions > 3. That's what I find so hard to understand about the criticism of string theory. If nothing else, there is lots of theoretical insight in string theory. If it really describes our world is a completely different issue. Lots of field theories are also studied only for theoretical reasons, having nothing directly to do with the real world. I don't want to wait for the unique prediction of my telephone number until I consider to find progress in quantum gravity interesting.

I'm no expert on the IKKT model, so don't know exactly what the problems with it are. If it really did give a well-defined, background-independent, non-perturbative formulation of M-theory, one that seemed to lead to dynamically determining a plausible background, my guess is that everyone in the field would be working on it. As far as I can tell, most people have lost interest in it. When that happens there's generally a good reason. Unfortunately I doubt that killing the IKKT model would kill the whole string/M-theory field.

I'm not claiming string theory is completely uninteresting. I am claiming it is overhyped and it has become difficult for young people to make careers working on anything else, which is very unhealthy. The reasons I don't believe in string/M-theory 11-d supersymmetric unification are two-fold:

1. It's really complicated and ugly

2. It not only doesn't predict your phone number, it doesn't predict anything at all.

 

[marcus]

The thing I wrote a few years ago ...tries to counter the extensive unbalanced hype about string theory ...

that's an extreme and incomplete condensation, I hope not unfair.

my point is that I don't think of that essay as primarily a polemic
it sounds to me more like the old and risky Quaker tradition of
speaking truth to power

which is rightly (I think) considered in that tradition to be an act of grace
and definitely more intriguing to watch than a simple polemic

Haelfix raised the issue of what is your "main beef" and got me curious.
He suggested it was lopsided funding. I want to try to get the essential
points isolated and in focus, at least for me. I don't hear a complaint (which is I guess what a beef is) and maybe I hear more a warning and a demand for integrity. Have to reflect a bit.

 

[marcus]

Peter Woit,

in your "An Evaluation" essay you make a mathematical comparison
between the Standard Model (where "two of the most important concepts... are that of a gauge field and that of the Dirac operator") and String theory
where those two concepts are "not fundamental, but are artifacts of the low energy limit".

You say:
"The Standard Model is dramatically more 'elegant' and 'beautiful' than string theory in that its crucial concepts are among the deepest and most powerful in modern mathematics."

this is something which as a non-expert with however some mathematical experience I would like to get in clearer focus. Maybe you have a alternative line of development in mind which does embody the strengths of 20th c mathematics in a more fundamental way.

It sounds as if particle physicists may have dragged things off into some place where they feel happy with the mathematics but which is not the direction theoretical physics is ultimately going to go and not, ultimately, in their own best interest. this is just a vague suspicion. sorry if too vague.

 

[notevenwrong]

Haelfix raised the issue of what is your "main beef" and got me curious.
He suggested it was lopsided funding. I want to try to get the essential
points isolated and in focus, at least for me. I don't hear a complaint (which is I guess what a beef is) and maybe I hear more a warning and a demand for integrity. Have to reflect a bit.

I think you've got it right. My point of view is that the over-hyping of string theory has lead to a really unhealthy situation in particle theory, and the remedy for this is for people to start honestly evaluating the results of the last 20 years work on the subject. I think if they do that they'll conclude that the idea of unifying the standard model and gravity in a 10/11 dimensional supersymmetric string/M-theory simply doesn't work. Once they get used to that idea, maybe people will start thinking about other more promising things.

 

[notevenwrong]

Maybe you have a alternative line of development in mind which does embody the strengths of 20th c mathematics in a more fundamental way.

It sounds as if particle physicists may have dragged things off into some place where they feel happy with the mathematics but which is not the direction theoretical physics is ultimately going to go and not, ultimately, in their own best interest. this is just a vague suspicion. sorry if too vague.

I tried to explain the alternative line of development I have in mind in
hep-th/0206135
That paper also refers to an old paper of mine in Nucl. Phys. B., which explains an idea about the relation of space-time geometry to the standard model.

This stuff is all very vague at this point, I certainly don't have a well-understood way of implementing many of the ideas that seem promising to me. This is all just as "Not Even Wrong" as string theory, maybe more so. But I think it's at least mathematically more attractive. If good mathematics leads to good physics, this may go somewhere.

 

[jeff]

As far as I can tell, most people have lost interest in it [the IKKT model]. When that happens there's generally a good reason.[/B]

This together with it's converse, that an ideas dominance speaks well of it's promise, makes your position more difficult to defend. Keep in mind that theory selection in an exact science like physics is very different than in the social sciences in which subjective opinion necessarily plays a much larger role.

 

[Urs]

As far as I can see research on Matrix Models is hampered by the fact that it is - difficult! :-)

When you hear the Potsdam group, Nicolai et al., speak about their reserach in supermembrane/BFSS model, you'll note that they will tell you that after fascinating results to lowest order (graviton scattering described by a simple matrix model, just imagine! :-) progress to higher orders is becoming really difficult, computationally.

The same seems to be true for the IKKT model. They have apparently run numerical computer programs for quite a while to see if they can approximately compute aspects of the exact solution, but they would need much more computation power to do that. I'll look up the links for you.