There’s an extended version of the interview of me by Susan Kruglinski in the February issue of Discover magazine that is now available, for free, on-line.
Before anybody starts yelling about AdS/CFT or topological strings when they read the headline “No one has a plausible idea about how string theory can explain anything”, I’ll just point out that, yes, it’s certainly plausible that some day string theory will explain something about QCD, and it already has explained some things in mathematics. The headline is a summary of some things I say in the interview, and in context it should have been clear I was talking about the use of string theory to predict anything not already predicted by the standard model.
Update: Harvard string theorist Lubos Motl has posted his commentary on the Discover article. If you read the comment section there, keep in mind that he is deleting comments from anyone who disagrees with him. I encourage anyone new to the current controversy over string theory to read what I have to say, read what Lubos has to say, and carefully look into the scientific issues involved to make your own judgement about what is going on here.
‘In mathematics there is much more of a culture where people spread out and devote their lives to thinking hard about something that interests them. … when the problems are very hard and no one knows what to do, I think people need to be willing to dig in and spend years thinking about something different than what other people are thinking. And there really isn’t the kind of institutional support within the physics community for this kind of behavior, whereas there is in mathematics.’
There is probably too much indoctrination in favour of strings to allow this. Physicists know it is highly unlikely that they could change the mainstream, so they prefer to stick with it. The fear of being blacklisted for non-standard ideas is quite real at the lower levels in physics. Those who rise to the higher levels usually have more mainstream ideas.
Peter, i enjoyed the interview. i hope it attracts some new readers. i’m a layman, but like your log anyway. i learned about the landscape through it, and about interesting links between math and physics. certainly it’s one of the more exciting sites on the web.
Peter says: “I was talking about the use of string theory to predict anything not already predicted by the standard model.”
Peter I guess you have to further correct your statement. You sounded as if you think string theory already predicts everything that SM predicts, it just does not go beyong SM. That’s far from being correct, not only has string theory not predicted anything beyond SM, it does not predict any thing that SM predict, either. It simply has not made any prediction whatsoever. Zero, Nada.
It’s important to point that out because we keep hearing string theorists make claims like “SM can be derived from string theory” or “string theory leads to GR” or so. Those are flat out lies. You can’t get SM starting from string theory. You can’t derive the Einstein Equation of GR from string theory. You can’t calculate any of the coupling constant or anything from string theory. Zero, Nada.
I also made some comment disputing the notion that just because string theory leads to very rich mathematical structures from a very few assumptions that it necessarily has to have something to do with the nature. My comments can be found on Lubos’s blog.
Quantoken
Peter,
what Yoga pose did you practice when they took the picture đ
http://motls.blogspot.com/2006/01/fall-of-discover-magazine.html
Not a bad interview for Discover at all, though few new revelations for the readers of you’re blog, I suspect. I look forward to your book for meatier exposition.
The photo…it’s not bad, it’s just I don’t get it. As we don’t normally find the math prof sitting cross-legged beneath the chalkboard, questions about why he might be in that position naturally arise. Perhaps he’s meditating?
Anyway, I can’t wait to see the Letters section of the subsequent issue! And, thanks for sharing the link.
Good grief! Remind me to never click on one of those trackback things again…I practically had an anxiety attack it was so laced with invective….
50 Most Loathsome People in America, 2005 If they only knew about Lubos
Peter, have you noticed that Lubos is your greatest ally in your fight to lower people’s regard for string theory? I would imagine that a lot of people who read the article will look at your blog, then look at Lubos’s review of your interview, and draw the obvious conclusion.
I’m not qualified to draw any conclusion except that level of rancor borders on frightening. I’m glad I’ve chosen to stay anonymous. Maybe it makes me a coward, but who needs enemies like that.
Merriam-Webster Dictionary on “approximation”:
or, on “approximate”:
These definitions in purely logical terms lead one to conclude that string theory cannot be an approximation scheme because the underlying theory to be compared with (viz., quantum gravity) is unknown. So in order to be an approximation scheme [to something known], string theory should be compared with a well established theory (or experimental data) in the regime where it applies (e.g., it should unambiguously reproduce — or approximate — the classical limit, SM particles, etc, that is, all fundamental observed phenomena that it is supposed to encompass or describe). But of course, things cannot stop there.
So, one is lead to conclude that such an “approximation scheme” should be somewhat viewed as an euphemism to “prediction” in order that things make sense. String theory must not only reproduce the physical properties of the fundamental constituents of nature to a reasonable precision [if is is to be seen as truthful approximation scheme to well known facts], but also predict new phenomena or indirect effects related to the Planck scale physics [if it is to be seen as a truthful quantum gravity theory at some stage]. Only then string theory can be more clearly evaluated.
Maybe Lubo has bipolar disorder?
he does not have emotions, but he has urges.
have you noticed that Lubos is your greatest ally in your fight to lower peopleâs regard for string theory?
It has been noticed.
anonymous said;
“… The fear of being blacklisted for non-standard ideas is quite real at the lower levels in physics. …”.
DB said, about Lubos Motl’s trackback blog link:
“… Good grief! Remind me to never click on one of those trackback things again … I practically had an anxiety attack it was so laced with invective … that level of rancor borders on frightening. Iâm glad Iâve chosen to stay anonymous. Maybe it makes me a coward, but who needs enemies like that. …”.
Those two comments (from people whose earlier comments have shown them to be thoughtful, reasonable, and intelligent) paint a very sad picture of a field that may be entering a Dark Age.
Are there any heroes of physics who might react to such “invective”, “blacklist[ing]”, and “rancor”
in a way similar to the way that the Boondocks MLK holiday TV episode showed King reacting to some negative aspects of today’s world ?
http://www.tv.com/boondocks/return-of-the-king/episode/614610/summary.html
I wish there were.
Even if not, as Huey Freeman said, “It’s fun to dream” that it might happen.
Tony Smith
http://www.valdostamuseum.org/hamsmith/
Sad to say, the author of Cosmic Variance’s ‘Best physics paper ever’, Isacc Newton, was quite as nasty as Professor Motl in his interactions with his contemporaries – even his ‘standing on shoulders of giants’ comment was a scarcely veiled insult to the diminutive and deformed Hooke. So Lubos is merely carrying on in a great tradition, albeit one that does not show physics and physicists in a very positive light.
I have a personal theory on Lubos Motl but I will never discuss it.
Science is obviously made by people, and people have a large spectrum of behaviours.
Christine, see film showing Motl’s hair growing as he attempts smile: http://www.kolej.mff.cuni.cz/~lmotm275/morf/lhm.gif
May it be best for all that Motl remains angry đ
Maybe we should try to comment on what Peter was actually saying about string theory – and not so much if we like Lubos or not? đ
(I’ll have to read the interview with Peter first, then I’ll post my comments).
Best, Kasper
Don’t know if Ed Witten will read this comment page and the message below:
Hi Ed Witten,
Please make a verifiable prediction from string theory to prove that the anti-stringy people are wrong. Then, Peter’s famous “Not Even Wrong” webpage will have the heading changed to “I was wrong”.
mathjunkie
HeHe…
That’s easy. Weakly coupled perturbative string theory predicts that there is an energy scale at which the massive excitation modes of the string are visible.
If true, this is verifiable.
What is not so easy is to falsify this prediction.
That is because the statement is of the form
“there is at least one x (in the set of energy scales) such that …”
Not observing any stringy modes below any fixed energy scale E therefore does not suffice to falsify this.
Note that even though this prediction is verifiable, it might well be wrong. It could be that strings exist but are not weakly coupled, so that perturbative string theory does not apply. It could also be that there are no strings at all.
But if you see any higher string excitation, then you have verified this prediction of perturbative string theory.
Vague non-quantitative ‘predictions’ are not scientific. Can you predict the exact energy of the massive excitation modes and therefore prove it is within range of experimental measurement?
“What is not so easy is to falsify this prediction.” – Urs.
Does this place string theory at the level of astrology?
In my opinion the situation is:
1) Quantum gravity likely gives undetectably small effects in any relatistic experiment.
2) Despite this, theorists studied quantum gravity hoping that it could lead to a unique theory of everything, able of predicting something.
3) Strings seem to give a unique theory, but in 11dimensions.
4) In string models the complicated physics that we see at low energies mostly comes thanks to a complicated enough higher dimensional set-up, rather than from theory.
I think that 4) is the reason that prevented strings to give so far results relevant for physics. It is often said that to progress we need “a deeper mathematical understanding of string theory”, but the real problem seems harder: we do not know the geography of extra dimensions.
(By the way: I posted a similar comment on Lubos blog, and it was deleted. Even if it is not possible to constructively discuss about physics, it remains my favourite trash show).
No. It is common for scientific theories to make predictions that are verifiable but not falsifiable.
The standard model demands that there is a Higgs field, but does not predict at which energy it will be found.
Not that there are no problems with string theory. But blanket anti-hype like “is not scientific”, “does not predict anything” are, in their crudeness, not any different from the original pro-hype like “will predict particle masses in a couple of months”.
You don’t have to like string theory. But if you reject it, you might want to do so for the correct reason, not just because you read the latest tabloid headlines.
But that’s the point. As long as the non-perturbative formulation of the theory is not fully understood it remains inconceivable how vacuum selection should be understood properly.
To Urs:
ok, one can try to study if non perturbative effects reduce the possible number of vacua from 10^500 to something more reasonable, or maybe even one. But this looks like hoping in a miracle, while the alernative view looks (at least to me) the true one: many vacua are possible, no vacuum selection mechanism exists, we are in one of them for no special reason.
a,
right, I agree. I just think that when, while doing research, you run into something that is getting out of control, you might want to pause and try to understand what is really going on at the fundamental level in the hope to get back in control again, instead of starting to wildly speculate and play around with a network of conjectures.
“It is common for scientific theories to make predictions that are verifiable but not falsifiable.
“The standard model demands that there is a Higgs field, but does not predict at which energy it will be found.” – Urs
But the Standard Model is only accepted for predicting many confirmed details about measurable nuclear interactions!
Kepler worked as an astrologer to live, because his alternative physics wasn’t popular, and astrology was in his day a highly mathematical enterprise (epicycles, etc.). String theory and astrology are similar in being unscientific uses of mathematics.
“You donât have to like string theory. But if you reject it, you might want to do so for the correct reason, not just because you read the latest tabloid headlines.” – Urs
If it can’t be falsified, nobody can disprove it. The real problem with string speculation is arrogance. With the mainstream embedded in untestable speculation, the subject is unhealthy. It would be better if there was more effort given to alternatives.
In the discussions here the target always tends to be moving.
If the statement is that
“People should look at alternative approaches.”
I have no problem with that.
If the statement however is
“String Theory is Astrology.”
then that’s nonsense.
String theory may be better than astrology and still not suit your needs. So go ahead and work on something else.
Incidentally, to outsiders it seems like there are a lot of venemous attacks going on in quantum gravity.
Be assured, the statement holds true in a number of fields in physics. If you go to a lot of astrophysics and phenomonology meetings invariably you end up seeing the same childish name calling and intellectual chest pounding (at least, on occassion).
But many of us have learned that thats a good thing in the end, some people just need that sort of fire and controversy to keep working and motivated to keep an edge. Its also vital to remain skeptical of everything and anything (that includes above all, yourself) so controversy really serves its purpose in physics.
People get used to it, and then its all fun and games thereafter.
Indeed. I think it is a good thing to have a critical discussion of the topics that are being critically discussed here (which usually is string theory and LQG, whether or not this is intended). I wish sometimes the dicussion would consistently be more fruitful, though. Let’s get away from that yellow press attitude towards research.
The following comment is seeking refugee status here after having been deleted on Lubos’ blog (like a’s above). It’s a bit less polite than what I would normally post, but should be seen as an attempt to communicate to Lubos in his native language. Since it was in response to his “review” of Peter’s Discover interview, where he once again derided Peter’s credentials, hopefully it is semi-on topic here.
……………………..
Lubos, it is disingenius of you to write that someones scientific credentials can be evaluated just by looking up their publications and citations. All of us working in physics know that it takes very little to publish a paper in a supposedly respectable journal these days. It can be easily done by following the general prescription of “monkey see, monkey do”, and some people have made careers out of this. Others have made careers out of riding on the coattails of famous senior colleagues, and it is quite amusing to see how some of these young “hotshots” go dead researchwise when put in a position of having to develop their own independent research program after getting a faculty position at an illustrious institution (not looking at anyone in particular, Lubos).
Citation numbers often have limited relevance as well, especially in “hot” subareas such as string theory where people are striving to churn out as many papers as possible and artificially inflating each others citation counts in the process.
To get a meaningful evaluation, the criteria need to be refined. The only physics journal that is non-trivial to publish in is Phys.Rev.Lett., so one possibility is to count the number of single-author publications a person has in there. How would you fare under this criterion, Lubos? Would you do better than Peter Woit, whose credentials you are so fond of disparaging?
(That was of course a rhetorical question. For those who can’t be bothered to look it up, Lubos has 0 papers in PRL, while Peter published a paper there on his own as a grad student.)
Urs,
“No. It is common for scientific theories to make predictions that are verifiable but not falsifiable.”
True. But the converse is wrong, and that’s the problem. Making verifiable but unfalsifiable predictions does not grant scientificity to a theory. You carefully omit to say this, but if Mathjunkie had said :
“Hi Ed Witten,
Please make a falsifiable prediction from string theory to prove that the anti-stringy people are wrong. Then, Peterâs famous âNot Even Wrongâ webpage will have the heading changed to âI was wrongâ.”
That would have been a far more interesting challenge.
Urs,
You neglect to mention that, besides massive excitation modes, perturbative string theory predicts a host of things that are clearly wrong (exact supersymmetry, massless fields, etc.) and would falsify the theory if you took these as serious “predictions”. On alternate days you argue that string theory really is a predictive science and that its predictions shouldn’t be believed (because we don’t yet know the full theory).
Urs:
It’s an insult to astrologists for you to compare string theory to astrology. Astrology is certainly not science, neither is string theory.
But Astrology is still way much better than string theories. Astrology at least make observations of the natural world and try to make connection with the reality world: They observe lunar phases and other astronomic phenomenas. Actually the ancient science of astronomy was developed on top of astrology. Today’s astronomers still have to rely on detailed written recordings left by ancient astrologists to get data on astronomical phenomenas that happen in the past, like supernovae explosions some thousands of years ago. In that sense, astrologists had made invaluable contribution to science, by making those detailed observations, and left detailed recordings of what they saw. That’s experimental science in its honesty!
What has string theory contributed to science? Nothing. They make no connection to the reality world whatsoever. They do not make predictions. Astrology at least try to make some predictions. The net contribution of super string theory is actually negative, by draining resources away from actually useful scientific researches in other fields, and by polluting the public’s perception of what science research is really about.
Lubos is poorly trained in basic physics instinctions and is not qualified to make judgements of science in general. See this post of his, appraising a stupid research idea, and my response below.
Quantoken
Actually, I was trying to be careful with always inserting the right qualifications. There is perturbative ST with some non-perturbative effects included by hand, and it does predict (in the weakly coupled regime) stringy effects. If there should be no viable phenomenological vacuum for this theory, then it is wrong. But I don’t know if none such vacuum exists.
We all need to be careful with making these statements. I could turn your accusation around and note that you oscillate between “predicts nothing” and “has been falsified”. Somewhere in between there is a truth.
But what if we do a perturbation about a flux compactification?
A few remarks about Lubos’s posting:
Ever since I’ve started publicly criticizing string theory, I’ve learned a lot about how academics behave when the facts are against them. The tactics employed are:
1. The ad hominem attack. Attack your opponent’s credibility and right to say anything on the subject. This is Lubos’s main tactic today. If you believe him that I shouldn’t be listened to, there’s not much point in me saying anything to defend my credibility. I’ll just point out that by now he and I have both written hundreds of pages about this controversy on our respective weblogs. Read large chunks of both of them and make up your own mind who is more credible.
In Lubos’s comment section there is a commenter “Hmm” who is also making ad hominem attacks on me and my credibility. Funny that whoever he/she is, they do this anonymously so that one has no way of knowing who they are, and deciding whether you should trust their judgements on this issue. Whatever you think of Lubos, at least he doesn’t engage in the sleazy behavior of making anonymous personal attacks.
2. The straw man attack. Misrepresent or even misquote your opponent’s words, then attack them as stupid and ignorant for saying something inaccurate. Lubos doesn’t much bother with this one today, but he’s normally quite fond of it, as are many other string theorists and string theory partisans that I have debated with.
3. Censorship. When you can get away with it, by any tactic available, keep people who disagree with you from being heard. Lubos is now doing that with his comment section, anonymous string theorist referees stopped Cambridge University Press from publishing my book, someone (presumably Jacques Distler) is using their influence with the arXiv to censor links to my weblog postings there. The internet makes this tactic less effective as it gives people who are censored various means to get their views heard anyway.
4. Intimidation. I’ve heard from many, many physicists that they agree with many of my criticisms of string theory, but are afraid to be publicly associated with them because of repercussions for their career. The over-the-top personal attacks from Lubos don’t help his credibility much, but they do frighten quite a few people into keeping quiet so that they don’t get subjected to this kind of thing.
The fact that the string theory community as a whole seems to have no problem with Lubos’s behavior adds greatly to this intimidating effect. It makes many physicists feel that if they criticized string theory they would both be the target of vicious personal attacks by Lubos, and, once targeted, behind-the-scenes retribution by his colleagues in terms of things like evaluation of their grant proposals, refereeing of their papers, invitations to conferences, and hiring of their students.
About the only string theorist around that I’ve noticed having anything critical to say about Lubos’s behavior is Aaron Bergman, who often comments here. The fact that no one else is willing to do so seems to me a deeply shameful commentary on the state of this field.
There is no known flux compactification which is phenomenologically viable or well enough understood to check if it is phenomenologically viable, or is there?
Dombono,
Urs kind of refers to this. One problem is that if you try and fully stabilize moduli using a flux compactification, you have to introduce non-perturbative objects like branes, and it is difficult to be sure that your perturbative expansion is reliable. It’s also true that even making optimistic assumptions about this, no one has come up with such a thing that is at all realistic or where you can calculate things and compare to the standard model.
Urs,
Yes, at times I both say “predicts nothing” and “has been falsified”, but I think I’m being consistent here. The situation is that string theory is not well-understood enough to make any reliable predictions. If you choose to believe in the unreliable predictions of the theory, on the whole they’re wrong.
In that so far every concrete vacuum which has been constructred is phenomenologically wrong. But since there are more vacua than have been constrcuted…
And so on and so on. We can exchange these arguments for ever, it seems.
Peter Woit said “… anonymous string theorist referees stopped Cambridge University Press from publishing my book …”.
Maybe I have just not been reading the web closely enough, but IIRC that is the first time that I heard of a book publisher bowing to censorship pressure from the string theory community.
Given the stature of Cambridge University Press, I am surprised.
Maybe I shouldn’t be surprised, given the “blacklist[ing]” mentioned by anonymous, the “invective” and “rancor” mentioned by DB, and some of my own personal experiences,
but
somehow it seems to me that censorship of book publishing takes the plunge of physics into a Dark Age to a whole new level.
The only ray of light that I see is that Peter was able to find a publisher with enough courage to publish the book: the English publisher Jonathan Cape – congratulations to the people at Jonathan Cape.
In fact,
that is yet another similarity between the situation in physics and the Boondocks MLK episode, in which “… CNN named Martin Luther King one of the 10 most unpatriotic Americans … His book was banned … King renamed his book “Dream Deterred” and it was finally released by a small publisher …”.
I agree with Peter’s statement “… The fact that no one else is willing to …[ criticize the situation ]… seems … a deeply shameful commentary on the state of this field. …”.
I guess that my Huey Freeman – type “dreamâ that some prominent string theorist might stand up against the descent of physics into a Dark Age will remain an unfulfilled dream.
Tony Smith
http://www.valdostamuseum.org/hamsmith/
About Tony’s comment,
I don’t want to make much of the censorship issue, since as I said I don’t think censorship attempts are very effective, at least not in this case. As for Lubos censoring his comment section, all it achieves is to have people post them here, together with the news that he is censoring them, not exactly adding to his credibility. As for the arXiv trackback issue, it’s not of great importance, and who knows, someday the powers that be may even get around to letting me know what is going on there, and the story may be different than the way it now appears.
As for the book, it’s being published June 1 by Jonathan Cape in the U.K., here in the U.S. by Basic Books in the fall. String theorist referees at Cambridge were within their rights to write reports saying they felt it would be a terrible thing if Cambridge published the book. I do wish however that they had felt it necessary to seriously come to grips with the book’s argument, instead of dismissing it out of hand. It was also not at all unreasonable for Cambridge to be unwilling to publish something over the strong objections of prominent scientist referees.
In the end, the publication of the book ended up being delayed a bit, but it’s now a significantly better book than the version Cambridge was looking at. I wasn’t ever that worried about it not finding a publisher at all. There’s a wide enough variety of publishers out there that sooner or later it would have found a home, although I’m quite grateful to the people at Cape for the encouragement I have had from them.
My God, Peter, they rejected your book? That makes me want to smash things. How did it come to this?
Urs – you’re a smart guy. Get out of that mess and away from those people.
-drl
Professor Woit,
Your interview in Discover magazine is really great. I enjoyed reading it. Any of Lubos’ commentary can be sent directly to /dev/null.
-Andy
drl,
Cambridge not wanting to publish the thing isn’t surprising, prestigious academic presses don’t often publish stuff that lots of prominent academics in the field would object to. In the end though, it is being published by some excellent publishers in Britain and here, who I think will even do a better job than Cambridge in terms of making sure it gets wide attention. Not a situation I’m at all upset about.
Peter said “… It was also not at all unreasonable for Cambridge to be unwilling to publish something over the strong objections of prominent scientist referees. …”.
Even if I were to agree for the sake of argument that it was OK for Cambridge to be unwilling to publish “over the strong objections of prominent scientist referees”,
I am still unhappy that the “prominent scientist referees” made such “strong objections” to the publication of a reasonable criticism of certain aspects of string theory.
If a theory or model cannot stand up against the publication of reasonable criticism, then it does not deserve to be considered scientific.
Peter also decribed the “prominent scientist referees” as “anonymous string theorist referees”, indicating that they chose to hide behind a shield of anonymity, which seems to me to be a further clear indicator of serious problems.
(Note that although referees MAY choose to remain anonymous, it is NOT required of them. In fact, back when I did refereeing for a journal, I disclosed my identity to those whose papers I refereed and gave specific reasons for rejections, so that if they so chose they could discuss the matters with me directly.)
Tony Smith
http://www.valdostamuseum.org/hamsmith/
Tony,
In the Cambridge story I’d just like to make clear that I don’t have any real problem with the people at Cambridge; their behavior was professional and not unreasonable. As for the string theorist referees, my problem with them was not the anonymity, that’s standard in this kind of situation. Actually of the two very positive referees, one I still don’t know who it is, one I do know (since he told me himself). There was also a mathematician referee who didn’t want to comment on the controversial parts of the manuscript; he was fine with letting me know who he was and we later had an interesting conversation about the mathematics involved.
I do agree with you that there was a problem with the behavior of the string theorist referees. They didn’t at all respond to the points made in the book, or find anything inaccurate there, but still chose to recommend strongly against publication. In an ideal world, a referee faced with a book by an author whose point of view they don’t like, but who has his facts straight, should not be so strongly objecting to its publication.
Since I’ve chosen to be cowardly, I’m going to try to limit my contributions to questions and very general commentary of a perhaps critical, but scrupulously non-pejorative nature, out of a sense of fairness. Don’t know if I have the self-discipline, but fair’s fair, so I should at least make the effort.