I have a long-percolating post that I hope to finish soon (when everything else is finished!) on “Why String Theory Must Be Right.” Not because it actually must be right, of course; it’s an hypothesis that will ultimately have to be tested against data. But there are very good reasons to think that something like string theory is going to be part of the ultimate understanding of quantum gravity, and it would be nice if more people knew what those reasons were.
Of course, it would be even nicer if those reasons were explained (to interested non-physicists as well as other physicists who are not specialists) by string theorists themselves. Unfortunately, they’re not. Most string theorists (not all, obviously; there are laudable exceptions) seem to not deem it worth their time to make much of an effort to explain why this theory with no empirical support whatsoever is nevertheless so promising. (Which it is.) Meanwhile, people who think that string theory has hit a dead end and should admit defeat — who are a tiny minority of those who are well-informed about the subject — are getting their message out with devastating effectiveness.
The latest manifestation of this trend is this video dialogue on Bloggingheads.tv, featuring science writers John Horgan and George Johnson. (Via Not Even Wrong.) Horgan is explicitly anti-string theory, while Johnson is more willing to admit that it might be worthwhile, and he’s not really qualified to pass judgment. But you’ll hear things like “string theory is just not a serious enterprise,” and see it compared to pseudoscience, postmodernism, and theology. (Pick the boogeyman of your choice!)
One of their pieces of evidence for the decline of string theory is a recent public debate between Brian Greene and Lawrence Krauss about the status of string theory. They seemed to take the very existence of such a debate as evidence that string theory isn’t really science any more — as if serious scientific subjects were never to be debated in public. Peter Woit agrees that “things are not looking good for a physical theory when there start being public debates on the subject”; indeed, I’m just about ready to give up on evolution for just that reason.
In their rush to find evidence for the conclusion they want to reach, everyone seems to be ignoring the fact that having public debates is actually a good thing, whatever the state of health of a particular field might be. The existence of a public debate isn’t evidence that a field is in trouble; it’s evidence that there is an unresolved scientific question about which many people are interested, which is wonderful. Science writers, of all people, should understand this. It’s not our job as researchers to hide away from the rest of the world until we’re absolutely sure that we’ve figured it all out, and only then share what we’ve learned; science is a process, and it needn’t be an especially esoteric one. There’s nothing illegitimate or unsavory about allowing the hoi-polloi the occasional glimpse at how the sausage is made.
What is illegitimate is when the view thereby provided is highly distorted. I’ve long supported the rights of stringy skeptics to get their arguments out to a wide audience, even if I don’t agree with them myself. The correct response on the part of those of us who appreciate the promise of string theory is to come back with our (vastly superior, of course) counter-arguments. The free market of ideas, I’m sure you’ve heard it all before.
Come on, string theorists! Make some effort to explain to everyone why this set of lofty speculations is as promising as you know it to be. It won’t hurt too much, really.
Update: Just to clarify the background of the above-mentioned debate. The original idea did not come from Brian or Lawrence; it was organized (they’ve told me) by the Smithsonian to generate interest and excitement for the adventure of particle physics, especially in the DC area, and they agreed to participate to help achieve this laudable purpose. The fact, as mentioned on Bloggingheads, that the participants were joking and enjoying themselves is evidence that they are friends who respect each other and understand that they are ultimately on the same side; not evidence that string theory itself is a joke.
It would be a shame if leading scientists were discouraged from participating in such events out of fear that discussing controversies in public gave people the wrong impression about the health of their field.
Gavin,
The problem with string theory unification is not that it doesn’t predict the result of every future experiment. The problem is that it doesn’t predict anything. I might not be completely happy with it, but I’d accept an ugly unified theory that made some predictions that were confirmed. I just don’t see the point of an ugly theory that doesn’t predict anything. Just “consistency” (especially if it’s only “consistency” at the standard level of physics argumentation, which usually relies on experiment to keep things honest) is not enough.
Stringtheory appeared on the scientific landscape, as a direct proposal to certain theoretical and physical unanswered questions. The “NEW” theory emerged with a mathematical formalism, that would take up the time and efforts of all fledgling genius’s, to the extreme.
Out of the new theory emerged new maths, which branched out into the need for new institutions, where the priveliged few could be left alone to formulate the “answers” to the pressing fundemental questions.
Answers were “not_forthcoming” with any real physical meanings, but what emerged were a plethora of “more” complex questions. For every question “early” stringtheory failed to answer, stringtheorists (who by now were looked upon as being Mathemagicians, or M-THEORISTS), created a vast pool of “More” questions, each question appeared, without the hope of having any real chance of giving a single answer, except in a “Magical”, or “Mysterious” way.
The Anthropic Egg was layed, when hatched, this egg would grow with the appetite of a Steroid fed Rooster, that devoured all the available “corn” that was meant to be shared around the sustainable “scientific/experimental” farmyard.
The Landscape was changed for ever, the cocks and hens that were reliant upon the corn for their existence in order to survive long enough to at least ask questions of stringtheory?, were reduced to the act of scavaging amongst the Rooster bird_droppings, this is no ordinary “humble pie”
Having to eat_s*it for long enough, a few fledgling birds are starting to spread their wings, and have learnt to leave the nesting grounds and fly away to a more sustainable landscape. Soaring high above, they can look down and see that there is more than one farmyard landscape, in this “new emerging natural” landscape, questions are tackled on “first_come” first served basis.
Stringtheory itself has a world “historical” line?..if they look at this historical timeline, then how can they defend the simple fact that the early reasons for their existence, have still not been addressed?..1984, and the “theory of everystring” has not been a good working hypotheses.
It has raised more.. more…MORE!…. exponential questions than answers. Stringtheory, by it’s very nature, is mathematically unworkable.
The Landscape needs to be turned into a new Garden. From it will emerge testable fruits that can be managed
and regulated, so it’s produce are not just sweet smelling, but fodder proof !
Peter.
Assume for the sake of argument that in the midst of every possible vacua of string theory, one day someone found something that looked exactly like the standard model, with a rather pleasent phenomenological spectrum at low energies. (Say something like a supersymmetric SO(10) gauge group theory, with the right suppression of fcncs, 3 generations, and a low amount of exotics, etc etc).
Assume also that someone managed to show that their was a mechanism that made the remaining vacua’s phenomenology extremely hard to deform into this particular one, so at the very least it looked somewhat unique.
Would you still object so vigorously to the construction?
You might claim its wishful thinking that we find such a thing, but do you object to scientists following their hunches and looking for precisely that?
Jacques invited:
I’ll take you up on your offer. Since the issue of relevance was Peter’s objection to the landscape in this forum, it would be nice if you could answer my four questions/queries here first, at least briefly. If you think additional elaboration would be better on your blog, that’s fine with me.
1. I don’t yet see the “standard model landscape” as a very compelling analogy to the string landscape. The standard model is (presumedly) an effective theory, developed with significant empirical input rather than derived as a logical consequence of a more general theory. Thus, we have no way to know at present whether most of the parameters of the standard model are derivable from a more fundamental theory that contains gravity. We also don’t know whether a more fundamental theory will contain the standard model as it currently exists or something much more extensive; hence, there is no way to know whether a landscape is inevitable. At least the way I understand it, the landscape was a very unwelcome addition to string theory, a consequence of a need to allow vacua that accommodate the observed accelerating expansion of the universe. So on the one hand it appears we have a conjectured landscape that might only exist if the more fundamental theory takes certain forms, while on the other hand the landscape is inherent if the more fundamental theory is to account for cosmological observations. Perhaps you can expand on this.
2. You point out that it is far from clear that the 100+ independent couplings of the MSSM can be independently adjusted. It isn’t clear to me how a “minimal” supersymmetric extension with 100+ parameters is an improvement over the standard model which has far fewer parameters; in my mind a more fundamental theory should reduce the number of the existing theory by deriving at least some formerly unexplained inputs, but that may just be my sense of aesthetics. The hope I have heard from MSSM proponents is that constraints will be found that relate many of these parameters, and hence substantially reduce their number. Is this is the hope you spoke of, which seems to me to be independent of string theory, or were you referring to specific string theoretic reasons for believing that not all of the various couplings are independent?
3. Are there any specific, string theoretic reasons for believing that only an extremely sparse set of vacua within the landscape can actually lead to universes that are compatible with life (whatever “life” is supposed to be)? That is, do any conjectures or other hints exist that indicate it is unlikely that two very similar solutions exist which equally well “predict” everything that we already know about our universe? Peter’s central point regarding the landscape seems to be that the answer is no, and will remain “no” regardless of any future experiments. (I’m excluding experiments that might show violations of Lorentz invariance, analyticity, and unitarity which, as commenters to an earlier post by Peter on the subject pointed out, are assumptions of almost all theories that people currently take seriously, not just string theory.) Do you disagree for specifically identifiable string theoretic reasons?
4. Assuming you believe the overriding goal of the string program is to obtain a scientific theory that gives deep insight into the most fundamental nature of the universe, do you believe that if the answer to my third question is “no” that it would be wise to shift at least a small amount of resources from the string program to the exploration of other speculative approaches to the same goal? Do you think it would be wise to make it easier for grad students with new ideas of their own related to “fundamental physics” to explore their non-string ideas as a thesis topic, even within a department dominated by string theorists? (It may sound like I’m trying to lead you to a particular answer here, but I am actually interested in your perspective as a string theorist on this issue.)
Thanks!
Sean Carroll has suggested in “Spacetime and Geometry”, that a consequence of a string-based scalar-tensor theory of gravity would be unambiguous measurable departures from ordinary GR.
He’s also suggested that detection of gravitational waves could provide a test for the proposed spin-2 graviton.
Are the opponents of string theory suggesting that there is any reason in principle for such tests being invalid?
Dear Lee,
There is a claim in your comment and book which deserves further consideration
You wrote: “My thesis, which is defended in the book, and supported by many statements quoted there and elsewhere by senior scientists in different fields, is that we do not do a good job of this and that we make it too easy for careerists with lots of competitivity and little originality and too hard for those who are really original and independent.”
Certainly, this is a central thesis in your book and there are several anecdotal examples and quotes from prominent people which seem to support it. I cannot say that I see a solid case for your claim or even see a clear suggestion how to study it. Still, this claim is somewhat appealing so let’s take it for the sake of argument for granted.
Suppose you have this great original young valley-crosser that you think deserves a position in Princeton or any other top place. Instead, because of the alleged bias he found a position in a second level university say Penn State. So what? He can make his original contributions from Penn State and when his ideas will prevail he will either move to Princeton or Harvard or else stay loyal in Penn-State and move his department to the highest level. And if he deserves a place in a second level university and will have to work in a third level one, again I do not see why it matters so much. Overall, the terms for doing theoretical resaerch are quite similar. (There is a difference in terms of students but having graduate students working on very original and high risk projects of their supervisors is a tricky matter anyway.)
With the divesity and large number of research universities even if you are right in your thesis I cannot see how it makes a big difference.
Perhaps something we can agree about is that the more bold, original and far reaching the scientific (and other) claims are the more careful and skeptical we need to be in studying them. For example, you mentioned Stu Kauffman here and also in the asymptotia thread where you referred to his idea to derive far-reaching conclusions in the theory of evolution from a result from mathematics known as the “no free lunch theorem”. This is certainly a highly original and bold idea. Do you really think Kauffman’s idea has any merit?
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The vacuum structure of the Standard Model, coupled to gravity is entirely determined by the low-energy field content (the graviton, the photon and the massive neutrinos). It is utterly irrelevant what the high-energy completion is. Indeed, even the inclusion of the electron (the next-lightest particle) makes only exponentially tiny corrections to the vacuum structure.
Unwelcome, or not, the existence of an exponentially large number of metastable vacua (once one fixes the moduli) is a feature of String Theory. Some of these vacua have positive cosmological constant; others negative. This would be true, even had it turned out that we didn’t live in a universe with positive cosmological constant.
“Adjusted” is, perhaps the wrong word.
Let me remind you of a few salient facts about the Landscape.
1) Consider an integer lattice Z^n. The number of lattice points inside a ball of radius R scales like R^n. In the IIB flux compactifications that people consider nowadays, n is the number of cycles on which one can independently place fluxes. The fluxes are quantized, and obey some tadpole cancellation constraint. So, to find the number of solutions, one is counting the number of lattice points inside a ball of some radius. Since n can be in the hundreds, this is a very large number.
2) Another feature common to these models is that the degrees of freedom that give rise to the visible-sector gauge group and its matter content are localized on the Calabi-Yau. Most of the “n” cycles are disjoint from the locus where the Standard Model degrees of freedom are supported.
In each of the R^n vacua, one has a low-energy effective theory. Most of these can (if we are particle physicists) be discarded immediately, because they look nothing like the real world. (It is exactly on these grounds that we ignore most of the landscape of vacua of the Standard Model.)
What remains is still a very large number of vacua. These form a discrete set of points in the parameter space of (some supersymmetric extension of) the Standard Model.
The fear is that they fill that parameter space “densely” (in the colloquial, rather than the Real-analysis use of the term “dense”). To within experimental accuracy, we would be able to “fit” any measurement of where we lie in that parameter space by one of these vacua.
But there are solid reasons to believe that this fear is unwarranted. The vast majority of the “n” cycles are disjoint from the locus where the Standard Model degrees of freedom are supported. And so the precise distribution of fluxes on those cycles do not affect the renormalizable couplings of the Standard Model at all. Only n’ ≪ n cycles intersect this locus, and affect the Standard Model couplings. Rather than R^n points, densely filling the parameter space of the MSSM, we have a sparse set of R^n’ points.
And thus, some real predictions…
(Just to be clear, the cosmological constant, and possibly certain other soft operators, depends on the distribution of all n fluxes. So we still expect a dense set of values for it.)
I’m sorry.
I am utterly uninterested in Anthropic arguments. Ask someone else.
Proof by assertion is not an argument.
I’ve explained why I think it is likely that, when we manage to find a family of vacua which bear more than a passing resemblance to the Standard Model (so far, we haven’t), they will have a sparse distribution of values for the parameters — both those which have already been measured (which can, if you want, be used to further prune the vacua which bear looking at) and, more importantly, of the parameters we have not yet measured.
Since we haven’t yet found the family of vacua we are looking for, my argument can hardly be called ironclad*. But it is a good deal more persuasive than the mere assertion than “You can get anything you want on the Landscape.”
In any case, if you’re going to go around repeatedly making the latter assertion, then you have to explain why the above argument is wrong.
I am a firm believer in the proposition that graduate school is the time when you should work on all kinds of crazy ideas.
Most students (even the very brightest) enter graduate school without much of an intuition for what will work and what won’t. Developing that intuition is a lot like learning to walk. You tend to fall down a lot. Graduate school is supposed to be a place where you can do that “safely.”
I think it would be a terrible idea for graduate students to blindly follow some set of ‘marching’ orders from their professors.
It sounds like you had a more specific proposal in mind. If so, you’ll have to explain what it is, if you want me to comment on it.
* If we had, I wouldn’t be presenting you an argument, I would be presenting you a calculation.
Peter,
Do you see any approach to unification that will make testable predictions?
Dear all,
I like the analogy between scientists and mountain climber. Indeed, scientists are a little like mountain climbers. The sense of beauty of an unexposed territory, the loneliness, the prolonged difficulties, the need for stubbornness and flexibility. There are dangers in both occupations; For example, prominent hazards for mountain climbers are crevasses. Those (wikipedea tells us) are the slits or deep chasms formed in the substance of a glacier as it passes over an uneven bed. They may be open or hidden. In the lower part of a glacier the crevasses are open. Above the snow-line they are frequently hidden by arched-over accumulations of winter snow. The detection of hidden crevasses requires care and experience. Scientists’ crevasses are not deadly but they exist, and so is the danger of getting lost and of losing the skills.
My approach (from my tea-cup VI discussion with Lee) that young scientists should not be encouraged to do high risk endeavors was part of my view that they should not be encouraged at all . In this spirit let me fantasize a meeting between Lee Smolin and a young Ph. D. candidate called Jeremy.
Professor Lee Smolin: Please sit down. (Look at Jeremy’s file) I understand you graduated last year from Harvard University, .., straight A, … hmm junior thesis on the paper: “On the relationship between quantum and thermal fluctuation,” What bring you here, Jeremy.
Jeremy: I would like to write a Ph D thesis under your supervision.
LS: (looks at the file, this is the best file he saw for years…): I see. Let me tell you something right away Jeremy. A success as an undergraduate does not always mean a success in research, but looking at your file I am willing to take the risk and say that I think you will be able to write a good Ph D thesis.
J: Thank you.
LS: You must know that an academic job afterwards is not guaranteed. It depends on your success in research but also on many other factors.
J: I am aware of that fact Professor Smolin.
LS: (after a long pause). Young man, let me ask you a question. You did brilliantly at Harvard and you can really succeed in life. You can get out of here in one year with a Master degree and then go and become a successful man. If you want to be rich, you can go to business or high-tech and even to wall-street and if you want to build things you can go to engineering and if you want to help people you can go to med school. And whenever you go, you will be surrounded and work with real people, not mainly with formulas and computers. And, you know what, Jeremy, with a normal job, there is even a chance you will pay attention to your wife and children when they will talk to you rather than day dream about physics…
J: But I want …
LS (interrupts): Look, don’t give me an answer right away. Think about it. Take, two three weeks to think about it, Jeremy, and I will be happy to continue our conversation then.
Lee of course knows that Jeremy will most likely come back, and will complete an excellent Ph D thesis. And then at times when he will be cold, wet and lonely on these mountains he will remember that graduate school was not something he was drugged to but truly his choice.
Hi Prof. Smolin, re.#217:
What criteria do you propose to use to determine if someone is a support-worthy seer/valley crosser? One person’s seer may be another person’s crackpot. Where one person sees highly original, surprising ideas, another may see speculative, ill-founded nonsense. I don’t see how there could ever be an objective way to decide this. Even such eminent scientists as Feynman and Gell-Mann couldn’t agree about the merits of John Schwarz.
For that matter, one person’s careerist may be another persons honest researcher who is just trying to do his/her best in the system they find themselves in. And I really don’t think you should invoke that kind of demeaning image to contrast against the type of people you would like to support. Criticizing sociological aspects is fine, and I also do it, but putting a question mark against the integrity of (some of) the people who succeed under the current system is just offensive. Without looking into their hearts you can hardly know whether careerism or desire to contribute to science is the underlying force that drives them.
Please, rather than more social engineering (i.e. preferential weightings not only for research areas but now also for certain types of researchers) can’t we just agree that the thing that matters is to reward advances in physics in proportion to the size of the advance, regardless of whether it came in the form of an original surprising idea, a technical calculation, or whatever, and regardless of the topic the person is working on. If we can agree on that then I don’t think it would be so difficult to adjust the current system to implement it. The mathematicians have shown how it can be done. In exceptional cases accomplished senior people should have the possibility to step in and help a struggling youngster who they consider particularly promising (just as Gell-Mann did for Schwarz), but that possibility seems to be already there in the current system.
Btw, I’m no historian but was under the impression that the rise of US science in the 2nd half of the last century was mainly due to the influx of many great scientist-refugees from Europe at the time of WW2. Are you sure it was not this but the availability of jobs that produced the rise in the US science level?
Looking for ‘defence’ from string people?
Then shouldn’t we already take into account the popular books written by them which, without specifically addressing the vocal critics, do attempt to give a good picture of the current state of research? For example those by Brian Greene, Lisa Randall, Lenny Susskind. I think this kind of book is a much better use of time and effort than pursuing “the intestine shock and furious close of civil butchery” which the public debate currently resembles.
A big question here is whether it is worthwhile for any ‘string person’ to write a book and go on a long publicity campaign purely in order to provide a counterweight to Woit, Smolin, Horgan etc. There are a few factors coming in here. First, that would take several months, and few string-ers want to take such a time off from actually doing research. It seems to me the books and publicity blitzes are coming from people whose research field is rather less crowded and busy than strings, who therefore, on average, have more free time… Second, if the arguments being offered against string theory are sociological or irrelevant or highly subjective, and it seems that many (I don’t say all) of them are – judging a theory by the amount of nervous laughter? – is it worth anyone’s time and effort to go into detail rebutting them? Who on earth would read a book specifically devoted to answering or debunking everything said by Woit and Smolin?
T
Haelfix,
What I think about this kind of hypothetical depends on the details. You conjecture something that looks just like the standard model, but describe something rather different. There are certain quite distinctive features of the standard model (gauge groups, representations, fermion mass matrices), which if you came up with a model which uniquely determined them, it might be convincing you were on to something (just getting the number 3 of generations is not like this). To be convincing, these would have to not be put in by hand, i.e. you’re not just looking at a huge class of models and picking out one that has desirable properties.
If you found such a model, depending on exactly what it looked like, it might or might not be very exciting. If you could actually compute accurately some standard model parameters, or predict something beyond the SM that was tested and came out right, it would of course be highly convincing.
The problem is that right now, if you look at any of the models people are studying, they are extremely far from this. I’ve looked at a lot of them, and all I see are things that don’t quite give the standard model, and are (unsuccessfully) being made more and more complicated trying to fit it. Maybe miraculously this will change and someone will find something very different. I just don’t see any reason to expect this other than wishful thinking, and wishful thinking is not a good motivation for a large-scale research program.
Gavin,
No, I don’t know of any really good ideas about how to get a testable unified theory right now. The best argument for string theory is that there aren’t other good ideas, but that’s not much of an argument for research on a speculative idea that clearly isn’t working. The crucial question for me is that of how to encourage people to try different things and look for new ideas, not keep pursuing one that isn’t working.
Dear amused,
I am sorry if I offended anyone, that was not the intention. It is better sometimes to speak plainly than to sound like a committee. It is simply true that there are people who try to game the system and pick their research topics based on an estimate of career advantage and there are people who have a deep desire to know and contribute and an aversion to playing competitive games. Granted many of us are mixes of both, I certainly was early in my career. Nonetheless, my claim is that something is wrong if the former easily succeed too often against the latter. We want the system to reward our best instincts, not our worse. This is an issue of values and I hope we can speak about them without seeming to offend people who may not share the values we advocate. The point is that any large system like the academy is not a law of nature, it is constructed in order to further the values of the people who build it and work in it. If we want to discuss how it works, we must discuss values.
As to your points, of course people will disagree, this is one reason that decentralization is good. As to looking into people’s hearts, this is an unavoidable part of the process of selecting promising young people. One is opening up opportunities or not based on a bet on the long term success of someone, and motivation, ambition and character matter as much as the kinds of technical skills that can be tested objectively. One does this with a large dose of humility, knowing one can be wrong, but there is no way to avoid doing it. Every search committee and panel I’ve been on does it.
It is true that sometimes senior people play the role of an angel (in venture capital terms) to protect a young person and a new idea. This is good. But it becomes harder to do as hiring and funding procedures become more formalized.
I agree with you that what is required is not large changes to the system, but small adjustments. The kinds of things I and others propose in this direction is no more “social engineering” than the present system, and they are proposed mostly as additional initiatives. Indeed my point is that rather small changes could make a big difference. Small initiatives like founding one small institute, or starting a new foundation have in the last years made big impacts.
Dear Gina,
Of course one tries to discourage people, and conversations like the one you script have been part of the initial discussion with prospective grad students for decades. I do it and many people I know do it with all prospective students. The questions I am asking start a bit later, and concerns those who will not be advised or discouraged out of risky and ambitious attempts to contribute to physics. At some point, when a person has proved they have the ability to come up with new ideas that are ambitious and worth working on, they need our support.
Lee
Peter,
The crucial question for me is “what should I study.” The lack of other good ideas may not be an argument for studying string theory, but “try different things” isn’t a very focused research plan.
This isn’t an academic issue. I earned my Ph.D. and published a couple papers. Then I took several years off to be at-home dad while my wife established her career. Now my son is in school full time and my wife is a partner, so it’s my turn to pursue my interests. I’ve been talking to people in high energy theory about my options and they have two suggestions:
(a) Do string theory
(b) Don’t do string theory
The people advocating (a) have some pretty specific ideas about what to do, but the prospects for experimental test are bleak. So I’m looking for some clarification on (b). Can we narrow that down a bit? Is there something I should read?
Gavin,
Given that there’s no clear way forward at the moment, I think it’s hard to offer anything other than some very personal prejudices and guesses, and encourage other people to come up with their own, preferably new and different ones. I see a lot of interesting questions about the relation between QFT and mathematics that are waiting to be explored. One that has gotten attention is Witten’s recent work on the relations of QFT to the geometric Langlands program. There are lots of others, which I’ve tried to mention on the blog. Generically, I think it would be worthwhile if more people were just taking whatever aspect of QFT they had always found most intriguing and mysterious, and trying to learn more about it and seeing if they could come up with something new.
On the less mathematical side of things, the LQG people do seem to be looking into a variety of different questions that seem worth pursuing. In QFT itself, chiral gauge theories remain extremely poorly understood outside of perturbation theory. For example, it’s remarkable to me how little interest there has been in the question of how to properly define the electroweak theory outside of perturbation theory, e.g. by finding a computationally useful way of doing calculations on the lattice.
Peter
I wrote
It’s worth emphasizing that, while I may have phrased the argument in terms of Type IIB flux vacua, it’s actually quite general and applies to any class of vacua which satisfy
1) There’s an exponentially large number of vacua, corresponding to the different ways of distributing (quantized) flux among n different cycles.
2) The Standard Model degrees of freedom are localized on the compact manifold, and only a much smaller number, n’≪n, of cycles intersect that locus.
This describes Type IIA flux vacua, M-Theory on G_2 manifolds, … In fact, it describes all of the classes of vacua for which we currently understand moduli stabilization.
So I see no merit to Peter’s ‘you can get anything you want’ claim, with regard to any of the known branches of the landscape.
As to his fallback position that the string theorists’ constructions of these vacua are ‘complicated and ugly,’ I would ask you to reflect on whether this is an objective scientific judgement, or merely a symptom of Peter’s general distaste for string theory.
Gavin,
Why not have a look at the particle physics via non-commutative geometry stuff that Connes, Marcolli, and others are doing? There’s a lot of interesting questions there, conceptual and computational.
Dear Prof. Smolin,
I guess you must have in mind specific people who you are sure have achieved their success in the current system through gaming it. It surprises me that this is something that one can know for sure.
I don’t suppose there’s any chance of you giving the names…
I would like to offer a hypothesis, that if subjected to scientific scrutiny, would put string theory to shame.
The proposed hypothesis is that reality is much like a spectrum of radio waves. Multiple radio stations, or realities, are available to us, but we only experience one wavelength at a time. We experience only the channel that we are focused on–or tuned into–at any given time.
Perhaps reality is the same way. There may be an infinite number of realities, all of equal validity and “realness” as the one we live in, but if we simply had the ability to tune in to the others, we might learn that there is no end to them. Perhaps we would discover that there is an infinite number of alternative realities, all just as solidly real as the one we live in.
As a lay person, it seems to me that much of what quantum physicists have discovered lately at least hints of this possibility.
Dear Amused,
Of course I won’t mention names, as my interest is not at all to attack or judge anyone, it is to have an open discussion of what values we think lead to the most scientific progress, and what values hinder it. Nor do I tend personally to judge individual people badly, we live in a very imperfect system and within the boundaries of ethics there are many strategies to a successful career.
If it would help I can speak of myself. I made two major compromises in my career, which I believe hurt my contribution to science. First to not concentrate much on foundations of quantum theory till recently; even when I had tenure it would have endangered our group’s research funding. Second, I spent a long time working on different faint hopes for perturbative quantum gravity before striking out into what I knew from the beginning was more promising but more risky, which was developing non-perturbative techniques. Even if my first paper was on a non-perturbative approach, most of what I did the next six years was perturbative and while it advanced my career it did not lead anywhere.
So I am talking from experience. I would have much prefered to work in a system where I could have dived into the problems I perceived were the deepest from graduate school on. Then I felt I had no choice, indeed there were peers of mine who were deeper and purer thinkers with much more talented than me who did not survive in academia. Now many years later I want to improve the system so other, better, people are not faced with the same choice. I do this not out of romanticism but because I believe there is lots of evidence that this would improve the progress of science. As I said, many very experienced people across the sciences appear to agree.
Lee
“Peter’s ‘you can get anything you want’ claim”
I don’t claim that it is possible to get absolutely anything out of string theory compactifications. Very specifically I do claim that I have seen no argument from anyone working in this area that these compactifications cannot lead to values similar to the SM ones for the data that characterize it (number of generations, gauge group and couplings, fermion representations and mass terms). Devotees like Jacques of so-called “swampland” studies are trying to show that certain kinds of effective field theories cannot occur this way. So far, they have only made arguments that turn out to be wrong (someone more knowledgable than them explains how to get what they said can’t occur), or are claiming to rule out theories very different than the standard model, ones that seem to be irrelevant to the real world.
“As to his fallback position that the string theorists’ constructions of these vacua are ‘complicated and ugly,’ I would ask you to reflect on whether this is an objective scientific judgement, or merely a symptom of Peter’s general distaste for string theory.”
Here I’m not relying on my aesthetic sensibilities, but quoting Lenny Susskind. In his recent book, he refers to these constructions as “Rube Goldberg machines”, and makes fun of the idea that string theory constructions are “elegant” or “beautiful”. If Jacques does believe these things are not complicated and ugly, instead of attacking me as prejudiced and not worth listening to, I suggest he go after my source, Susskind.
Without taking up to much room I thought I would link this in terms of valleys and hills.
You do claim that the Landscape renders string theory unpredictive. That means (if it means anything at all) that any values for the 100+ parameters of the MSSM can be accommodated (to within any foreseable experimental precision) by one of the vacua on the Landscape.
If that’s not what you’re claiming, then please clarify your claim.
I just gave a very general argument that if the Standard Model is found to be in the same general class of vacua as those which have been explored in recent years (an assumption which could, of course, be wrong, but one which is tacitly assumed by Susskind and, therefore one assumes, by you), then the above claim is wrong.
If you have a counter-argument, please make it. Otherwise, stop going around making unequivocal statements like
or
or
or
(All from this comment thread alone; you have made similar, but much more emphatic, statements elsewhere.)
Obviously, no one has yet found a convincing candidate for the Standard Model, among the string vacua explored to date (in that sense, no one has made any predictions yet). But that’s not what you’re saying. You are claiming that the framework itself is inherently unpredictive.
I have argued that claim is false.
Do you have a counter-argument?
Lenny and I agree that æsthetic judgements are not an objective scientific criterion. You’re the one claiming that the “ugly” nature of these vacua is reason-enough to abandon the whole field.
Jacques,
> Obviously, no one has yet found a convincing candidate for the Standard Model
so what about te claim of Eric Mayes in comment #22
“we can now competely derive the MSSM from string theory [..]” ?