Gosh, a thoughtfully-written general level (more or less) article on some of the general outcomes of string theory research! It’s written by Matthew Chalmers, and is in the Sept. ‘07 edition of Physics World*. The article can be read online here, and downloadable pdf is here. The graphic on the right came with the article. I don’t fully understand what it is, but the title, like that of the article, is “stringscape”… Look, let’s not over-think this cvj - it’s a pretty decoration.
I’ve done a quick read of it (should re-read more carefully later on - it will no doubt have some emphases with which I disagree somewhat**) and I’d say it is very much worth reading. While not a perfect summary (what is?), compared to a lot that’s been out there, you’ll find it rather more informed, less sensational, (refreshingly unpoisoned by various prejudices, such as the presentations of Smolin and Woit - see numerous earlier discussions in the “More Scenes from the Storm in a Teacup” series of posts, and others), and unafraid to go to some length to unpack the issues somewhat carefully.
Very importantly, it contains numerous quotes from various respected researchers in physics (some working on string theory and some not), and it is good to read to get a sense of the layers of views that prevail- contrasting, disagreeing, agreeing, hopeful, pessimistic, doubtful, optimistic - and the focus is the science, not sociology. Such a diversity of views, with a prevailing pragmatism (i.e.: “we’ll work on whatever good idea helps us make progress, strings or not strings”), is present in any healthy scientific endeavour, at any point in history.
As far as I can see, the short summary of the summary seems to be what I’ve been saying time and again here (but read it yourself for some of the reasons why, and maybe also to come up with your own summary, which could well differ from mine):
Will it tell us important new things about nature? It’s a work in progress - Too soon to tell.
(I should add, as usual: …And in the meantime we’re learning so much from it, shaping useful tools with many potential applications, and training so many young people in important techniques from all over physics and mathematics… etc, etc.,…)
Enjoy!
-cvj
___________________________________________________________________________________
*Thanks Oliver! (It’s been out for a while, and I completely missed it!)
** For example, I don’t agree that “most string theorists think [...] that it is only a matter of time before the gravity `dual’ of real-world QCD is worked out”. The issue is much more interesting and subtle than this. See my thoughts about this issue here.
On this day on Asymptotia...
- Soon They Will Come - 2007
- Converting The Enemy - 2006
- Ranch Style - 2006
Some Related Asymptotia Posts (not exhaustive):
- Lookin' For Some Hot Stuff
- Exploring QCD in Cambridge
- Questions and Answers about Theories of Everything
- More Scenes From the Storm in a Teacup, VII
- Masterclass
- More Scenes From the Storm in a Teacup, VI
- More Scenes From the Storm in a Teacup, V
- More Scenes From the Storm in a Teacup, IV
- More Scenes From the Storm in a Teacup, III
- More Scenes From the Storm in a Teacup, II
- More Scenes From the Storm in a Teacup, I
My problem with large N QCD is that real world is not large N. Furthermore, the only possibility I have seen to stablish some supersymmetry play at the level of hadrons works uniquely for three generations and SU(3) color, where a pair of quarks have the same color charge than an antiquark and you can try quark/diquark susy.
Hi Alejandro: N is the inverse string coupling, so the nature of the corrections to the strict large N limit are accessible by studying corrections to the leading string results. Also, the supersymmetry is not really relevant, it seems, for lots of things being studied - the string theories are not supersymmetric in the regimes being studied. Please read the post I pointed to for why a lot of these details may be less important than they might seem. The upshot is that these are not QCD, but may give us access to many physical properties of value that are shared by QCD.
-cvj
That is a beautifully written article, the kind of article I’d enjoy reading if I wanted to get a glimpse of a subject far from my expertise (rather than just forming an opinion on it). I’d definitely be bored reading articles about what some micro-biologist or economist think about their colleagues, carefully avoiding any mention of micro-biology or economics. I am glad to see some movement away from that tiresome genre.
Clifford,
My repeated attempts to post a comment about this here have been blocked, presumably by your spam-filter. If you can unblock one of them, that would be helpful.
Sorry Peter. I did not see the spam filter doing this. I’ll have a look. If I find it, it will appear with the earlier timestamp and hence above your comment #4, and so I will change the timestamp to have it appear below, so as not to confuse.
Anyhow, you seem to have succeeded now.
Cheers,
-cvj
There was an extensive discussion of this article at my blog two weeks ago, see
http://www.math.columbia.edu/~woit/wordpress/?p=593
This included an extensive exchange with the author of the piece. Anyone reading the Physics World piece should be aware that it contains quite a few inaccuracies and large amounts of hype, together with some information that is simply unarguably out and out false (no, Witten did not win a Fields medal for his work on Calabi-Yau compactifications of string theory). The same issue of Physics World contains several other shorter pieces about string theory, discussed here:
http://www.math.columbia.edu/~woit/wordpress/?p=599
These include a piece by theorist Fred Goldhaber describing currently popular work on the string theory landscape as “antiscience”, and a piece by philosopher’s Cartwright and Frigg that explains why just repeating “it’s too soon to tell” in response to criticisms of a research program is not enough.
As for whether Lee Smolin and I have written uninformed, sensational books poisoned by prejudice, note that Clifford is famous for steadfastly refusing to read these books (or my blog, it appears, since the “Stringscape” article is new to him), making his views on our arguments well, uninformed and poisoned by prejudice, I would say…
[originally had timestamp 11:22am; see previous two comments- cvj]
Hi Peter,
1) The issue of whether I’ve read the books or not is -as you know- a red herring. We’ve been discussing in detail the content of your arguments together for almost three years now. I don’t need to read the books for that. I’ve been talking about the content of your arguments and debating them with you. It’s an obvious distraction to continue on about that issue. (Recall that my discussion of your arguments with you was so convincing for two years that you in fact went as far as to make up the story and publicly announce that I’d reviewed your book for the publisher CUP, only to have to withdraw your claim later. So you’re trying to have your cake and eat it.)
2) This is a scientific discussion. When asked in many places to defend your scientific claims with a scientific argument, you failed miserably to do that, as anyone can read in the discussion threads that I’ve pointed to in the post above. Hiding the lack of scientific content of your arguments in lots of fluffy stuff in a book is not how we do scientific discussion in physics.
3) You are entitled to your opinion and gut feeling about the rightness or wrongness of what we are doing (based as they are on an oft-demonstrated lack of understanding about most of what is going on at a technical level, but that’s ok), but dressing that opinion up as scientific fact and deceiving the general public and the yes-men who read your blog (I certainly don’t!) into thinking it is scientific fact is not a good thing to do.
4) The other reason I (and many others) don’t read your blog is because the whole one-note song is tiresome and boring. You just sit around waiting for negative things to say about string theory. You can’t help yourself but ignore anything positive and jump to find the most negative conclusions that fit your already firmly formed view. Most of us just want to stay neutral about the whole thing -pragmatic. We want to get on with doing the research (or letting others who know what they are talking about get on with it) and let the results determine our opinions, rather than decide before hand. Open-mindedness vs prejudice, you see.
5) While I’m on the topic…. rather than sitting around waiting to pounce on everything everybody says about strings, wouldn’t it be a whole lot more productive to do some research on your own approach, and produce an alternative that does a better job?
6) These remarks (points 1-6) have all been said so many times, by so many.
Thanks,
-cvj
Clifford,
You don’t know what my arguments are since you refuse to read them. As to why I thought you had read them when you hadn’t, it wasn’t because you showed any signs of knowing what my arguments actually were, it was that it never occurred to me as a possibility that an academic would even consider the idea of writing long denunciations of a book they had never bothered to read.
As for your insults about how uninformed I am, don’t understand what I’m talking about, am just intent on deceiving the public, etc., they’re really tired. You have no idea what you are talking about since you refuse to read what I write, but think that this kind of insult and put-down is an appropriate response.
Thanks for your concern about my own research. I do spend a lot of time on it, and am making slow progress.
Hi Peter - the evidence is in all the blog discussions I’ve pointed to that everyone’s free to read. They can watch you stumbling around to make a coherent scientific argument when pressed for one (and trying several amusing schoolyard tactics to distract readers when you fail) to their heart’s content, and they can read myself and others addressing your key points head on over the course of the last two years or more. Pretending that those discussions don’t exist won’t help. They are part of the public record.
For the record, I denounced your arguments and claims - not your book, which I’d never read. However, I think I recall someone asking you in an earlier thread whether your book makes different claims than you’ve made on blogs and I don’t recall you saying there was a difference. My memory is possibly faulty on that, so feel free to come out and say that you’ve been saying two different things entirely.
I’m not trying to insult you about being uninformed. I’m really not. It is simply a statement of fact supported by the evidence. There’s lots of things I’m uninformed about and I don’t mind people stating it. However, I don’t claim to be an expert on those things and publicly condemn out of hand other people’s work on them, even writing books doing that, while at the same time not being able to support my claims.
Anyway, this is a tired circle we’re about to engage on and I’ll opt out. I’ll simply invite the reader who is interested to follow the nice trail you’ve left in all the posts I’ve pointed to, where you demonstrate your confusion between not liking something on the one hand, and having something scientific to prove on the other.
I’m glad to hear your work is going well. I wish you all the best. Perhaps you should consider letting others get on with their work too, rather than trying to poison people against it.
Best wishes,
-cvj
Clifford,
I’ll let people read exchanges between us here and elsewhere and decide for themselves which of us is best described as using “schoolyard tactics”.
The book is nearly 300 pages long and the result of a very serious and extensive effort to carefully write down my arguments on this topic. It’s a very different sort of thing than quickly written entries for blog comments section. There are many, many aspects of my arguments that are in the book, but not in blog comment exchanges. Both Lee and I have repeatedly tried to explain to you that if you want to engage seriously with the arguments of someone who has taken a lot of trouble to get them down coherently in one place, that’s the place you have to go to find out what they are. Your refusal to do so speaks for itself.
Besides the book, for something a bit more technical there are the slides of my talks earlier this year at physics departments in Rome and Pisa which I’ve repeatedly pointed you to. Again, that’s a second place you can find some of my arguments carefully laid out, and you’ve chosen to ignore them in that form also.
Regarding Clifford’s blog and the moderation of comments.
I used to read Woit’s blog but quit a year ago or so, partly after seeing them primarily used to support book sales (and mostly lacking other content) and partly in frustration over how he treated comments. His treatment of comments is far more draconian than Clifford’s.
It’s not about whether or not you believe in string theory. Personally, I think string theory is garbage. I studied QFT back in the early 80s. Eventually I wondered where the field had gone, so I picked up a text book on string theory and started reading it. Within minutes I was laughing at the mathematical errors and lack of physical intuition. 1 + 4 + 9 + 25 + … is simply not equal to -1/12 (or whatever they get). Spacetime does not have 11 dimensions, it has 3+1.
The fact that Clifford has failed to read the Woit and Smolin books, but still feels competent to comment on their content is a travesty. Clifford can intelligently comment on what he’s read, no more and no less, and what he’s read consists of commentary on these books, not the books themselves. One might as well take the stance that a physicist who has read commentary about a string theory book, but not read the book, can make intelligent comments about the content of the book.
But no, Clifford doesn’t moderate in a vicious manner. Woit’s comments hit the moderation queue probably because they had too many links in them.
Peter:
If you recall, I read those slides, and commented on them. How can this be interpreted as ignoring them? There’s nothing of technical substance there that would constitute your claimed proof that string theory cannot make contact with experiment. What you have is your version of a plausibility argument - not a proof of anything. Again, this is all in the comments of earlier discussions.
Best,
-cvj
By the way, now i read again the article… why does it says that the important work on dualities implying M-theory was presented in string95? I think to remember that most of the work was presented in Le Sorbonne in 1994, under the tittle Electric magnetic duality in four-dimensional gauge theories., simultaneous to the publication of hep-th/9407087 and with some slides related to hep-th/9408074. I was on the understanding that it was this presentation -read, you can say, in the same rooms used by Claude Levy-Strauss in 1968 - which was named as the “second superstring revolution”. Witten contribution in Strings 95 is hep-th/9507121, isn’t it?
I do rather ruthlessly delete comments submitted to my blog that are ill-informed and just add to the noise level, especially the large number from people who think that my blog is a good place to promote their personal “alternative” views about physics. While I rarely if ever delete comments defending string theory, I delete a very large number of comments that attack string theory in an ill-informed way. A good example would be one like Carl’s above. The problem with string theory is not that it uses zeta-function regularization or extra dimensions.
Alejandro asks:
It says so because that was when Witten made his announcement. The papers you refer to are about field theory not string theory. Note the title that you quote, for example, which gives a clue to the subject matter of the paper.
Carl: First of all it is 1+2+3+4+….. Second of all….. oh dear, never mind.
-cvj
Clifford,
I nowhere have ever claimed to have a “proof” that string theory can’t make contact with experiment. Without an actual definition of what “string theory” is, you can’t “prove” anything about “string theory” as such. One thing the slides contain is a discussion of all the various well-known claims for such a contact, and an explanation of the problems inherent in all such claims. The general reasons why such attempts to connect string-based unification to experiment don’t work are examined, and I think this provides a compelling argument that string-based unification is a failed idea. For nearly 25 years many, many people have worked very hard at it, and what they have learned has made clear what the fundamental problems are that keeps the idea from getting anywhere. I’ve made a serious scientific argument about why this idea can’t work (no, not provided a “proof” that it can’t). I don’t believe there is a serious scientific argument on the other side, giving some sort of plausibility argument about how these problems will be overcome.
This is the problem with your “too soon to tell” argument. 23 years of utter failure and increasing knowledge about how serious the problems are with getting unification out of a 10/11d theory just can’t be waved away this easily. The Cartwright-Frigg article explain how a scientific research program does not need to be immediately testable, but does need to be “progressive”, making progress towards such testability. The problem with string theory is that it is going in the other direction, making progress towards showing such testability is impossible.
Nothing new here to see.
I refer you again to the last part of my earlier comment:
-cvj
Yes Clifford, nothing new here. You continue to refuse to actually address the argument I am making.
The only thing I’m trying to poison is the less than honest hype that has surrounded string theory for far too long. You’re free to get on with your work on string theory, I’m not interfering with that in any way. You’re also free to continue to spend your time writing blog entries promoting overhyped advertising for the subject such as the Physics World article and attacking me as “ill-informed”. When you do this, I’ll continue to spend some time providing the other side of this story.
Partly due to my book and Lee Smolin’s, partly due to the ever-more-obvious failure of string theory unification represented by books like Susskind’s promoting obvious pseudo-science, I think people’s view of string theory is much more realistic these days. It’s unfortunate that, instead of adopting a realistic view of what has worked and what hasn’t, some string theorists feel that the thing to do now is to just increase the hype level. As long as they are doing this, I’ll spend some time poisoning such efforts.
I learnt about zeta function regularisation in string theory from David Gross many years ago and I must say that after only a little thought I shared Carl’s reaction.
Peter, in your blog you said:
“I think the great hope of some string theorists is that the LHC will see not only supersymmetry, but a pattern of supersymmetry breaking that corresponds distinctively to a certain kind of string background. Based on this they might then be able to make real testable predictions. This seems to me to be nothing but wishful thinking, we’ll find out in the next few years.”
I don’t see how you can call “wishful thinking” a serious argument. Do you think that it would be impossible in principle to indentify the pattern of SUSY breaking? Can you give a serious scientific argument?
Thank you!
Although I work in an unrelated field, I have come up with some challenging and contraversial ideas about string theory that are going to upset those in the mainstream.
Unfortunately I have to go out for a bit, so I can’t discuss my ideas right now, but I just wanted you all to know that I know that you are wrong.
Mark,
At one point I engaged in a detailed discussion about what people claim is the most robust “prediction” about supersymmetry breaking, that of gaugino mass ratios, you can find it somewhere on Cosmic Variance I think. The bottom line is that there are supersymmetry breaking scenarios that give you pretty much any mass ratios you want. Sure, if you pick specific backgrounds that people have studied, some come with constraints on the gaugino mass ratios when you make various reasonable assumptions. I understand that some people hope that the LHC will
1. see gauginos
2. find that the mass ratios fit the pattern of a certain class of backgrounds.
I just think that, while this is the best case scenario for the string theory unification program, it’s still highly unlikely. There’s zero evidence in anything we know about particle physics for this at the moment, and there’s nothing aesthetically or otherwise compelling about these backgrounds. Quite the opposite, they don’t explain a single thing about standard model physics, and these models are both spectacularly ugly and unpredictive.
Absent any evidence for this in anything we know about, hoping to see it at the LHC is not based on science, but on wishful thinking. It’s right up there with, say, large extra dimensions of exactly the right size so that the Tevatron sees no indication of them, but they show up at the LHC. This is not logically impossible, but there’s not a shred of evidence for it now, and it wouldn’t explain anything we do see.
It’s my impression that most particle physicists believe that extra dimensions are highly unlikely to show up at LHC scales, precisely because there’s no evidence for this, and no scientific reason to expect it to happen. I don’t think the supersymmetry pattern business is much different.
And there, ladies and gentlemen, you see the type of rigourous scientific argumentation Peter Woit uses to condemn an entire field’s scientific efforts.
See my point (3) in comment 7.
-cvj
Clifford,
No, I’m not “condemning an entire field’s scientific efforts”, I’m accurately describing the current state of efforts to use “string theory backgrounds” to explain anything about particle physics.
You, on the other hand, are behaving like a child. Grow up.
Name-calling. That’s really your response, instead of sharpening your argument-that’s-not-an-argument?
Mark asked “Can you give a serious scientific argument?”
-cvj
While I am inclined to take Clifford’s side in this dispute, there is one aspect of his approach that I find disturbing. He is always saying, “look, not all of us are working on the landscape! See, there are these other cool things like the [possible] application of AdS/CFT to heavy ions….”
[a] Does Clifford really think that the landscape is so disreputable? If not, he should make this clear, because I have the strong impression that he does.
[b] If the landscape story is really as screwed up as PW [and many others] think, then does Clifford think that he can just ignore this? Can one’s daughter be just a little bit pregnant?
Just to be clear: I myself think that work on the landscape and related issues is perfectly respectable. [Though I don't think that the landscape idea really works as usually advertised.] And I think that the way to defend string theory is to defend the landscape head-on, not by means of distracting talk about how wonderful string theory has been for mathematics or heavy ions, which really are very minor issues.
Hi Tilman Riemenschneider,
I don’t think that work on the landscape is disreputable. Where did I say anything like that? In fact, I did an entire (long detailed) post about the landscape and what motivates the research. See here. I don’t happen to work on it, and I think that there are several issues to be addressed about the basic question of what string theory really is before one starts declaring that the landscape is the chief issue concerning connecting strings to nature. It is important for people to work on it and explore it in the best way they see fit. Several are doing that. I’ve pointed out that there are several other efforts in string theory going on that are hugely important too. I don’t see what is wrong with doing that. The opposite is to characterize all that is important in string theory as some narrow range of effort and then criticize that effort. That’s Peter’s approach. That seems wrong to me.
Your characterization of the possible application of string theory to QCD and mathematics as minor issues is, I have to say, seriously misguided by the way. We’ll have to disagree on that.
Thanks,
-cvj
Can’t believe I am joining the fray here, but I gotta add my 2 cents and clear up the discussion on what the LHC can and cannot do. So here goes: The LHC will not be able to determine the mechanism that breaks supersymmetry. In fact, to be ultra-precise, the LHC will not actually be able to determine whether or not the new particles it will discover (note the optimism here) are supersymmetric or not. The LHC will be great at discovering new particles and will make gross measurements of their masses. Couplings, absolute branching fractions, spins, fundamental parameters in the Langragian of the underlying theory, etc. are all for the most part out of reach for the LHC. For these types of measurements you need experimental precision and the knowledge of the initial quantum state. I am as excited about the LHC as a person can be – I believe it will revolutionize our field. However, the stream of uninformed hype of what it can do is starting to get to me.
Clifford,
When I first started trying to respond to your attacks on me and my book, I couldn’t figure out why it was so difficult to have a serious discussion with you on the topic. After you finally admitted you hadn’t read the book, hadn’t read Lee’s book, and had no intention of ever doing so, it became clear what the problem was: while you were attacking me as ill-informed, you yourself knew very little about what you were arguing about, and weren’t interested in learning more.
I’ve been equally puzzled by your response to any sort of serious argument I make about what the problems are with using string theory backgrounds to get unification. When I make such arguments here and elsewhere, I often get serious, well-informed challenges to my point of view, from anonymous and non-anonymous commenters. From Jacques Distler I get a serious argument, together with sneering insults. From you, I’ve never gotten a serious response, just the sneering insults. It just struck me that there’s an obvious reason for this, the same one as in the case of your comments on my book and Lee’s: you don’t know what you’re talking about.
Looking over your book, your many papers and your blog entries, I couldn’t find anything at all that shows any evidence that you know anything about that part of “string phenomenology” which is concerned with seriously trying to get the standard model out of a string background. You never mention anything about the various proposals people work on in this area, what the problems with them are, what the prospects are for somehow getting something predictive out of them, etc. For example, the “long detailed” blog posting on the landscape that you refer a commenter to here is certainly not detailed. There’s nothing much substantive in it except a popular-level explanation of what an energy functional for moduli is.
Besides the books critical of string theory, I’ve noticed repeatedly that you often mention in your blog postings that you haven’t read some book or article that you are discussing. One example I recall is that you haven’t read Susskind’s book. You seem to be remarkably uncurious about and unwilling to learn about a wide variety of things, especially things that don’t fit with what you would like to be true.
There’s nothing wrong with deciding not to spend the time to understand what is going on in the field of string phenomenology. Certainly there are better ways to spend one’s time, and it’s a legitimate complaint about my behavior that I have wasted too much of my life learning about this instead of pursuing my own research. But if you choose not to inform yourself about something, publicly attacking people who have as “ill-informed” is truly disgraceful and unprofessional behavior.
Avoiding properly answering a straight physics question about your claims again, Peter?
-cvj
Clifford,
Your response speaks for itself. You don’t know anything about this subject, and that explains why it has not been possible to discuss it with you.
Avoiding properly answering a straight physics question about your claims again, Peter?
-cvj
Dear JoAnn,
Are you basically saying that from the decay signatures we will never be able to distinguish say, a decay of a chargino from a gluino decay? And if there is large missing energy, would not it be a sign of SUSY?
Thank you!
Woit: I agree that zeta regularization in itself is not a sign that string theory (and those parts of QFT that rely on this technique, and similar stuff like dimensional regularization) is wrong, or can produce no predictions. My point is that zeta regularization is a sign that string theory is no better than QFT in that it is only another effective field theory. It cannot be any sort of a consistent and complete explanation. An energy cutoff is a sign of a theory that doesn’t work at high energies. These alternative regularizations are just mathematically ugly ways of avoiding having to directly describe a theory that doesn’t work at high energies. String theory cannot possibly be a “theory of everything”.
The reason I hang around here rather than on your blog is that this one is a lot more entertaining. It covers lots of subjects. It regularly has cool photos. The comments come from all sorts of people and it doesn’t keep rehashing the same stuff over and over.
And by the way, it is rather unkind to imply that I wish to promote my “personal “alternative†views about physics” by abusing your blog comments. My work is accepted by the physics community to the extent that I have been cited in 4 peer reviewed journal articles with four different authors. This is better than any crackpot. Do compare “4″ with the number of citations your physics has picked up in the past year.
Since I’m a practical person who gets his hands dirty in industry, rather than an ivory tower intellectual, I have a useful and practical understanding of how to promote ideas. If I decide to promote my work, I will write a press release just like any other businessman. The title would be something like “Local Ethanol Engineer Finds Neutrino Mass Formula” and it would include links to the journal articles and probably a photo of me wearing a hard hat. I would send it to the Spokane Associated Press desk (which published a press release I wrote just a few weeks ago for my company). They would send it out on the wire and it would be picked up by a significant fraction of the world’s newspapers as a “man bites dog” story.
Hi Carl,
I just noticed that Robert has a nice post on regulating divergent sums here, which in turn will lead to a another post of interest.
I think that you’ve confused several things by the way, if you don’t mind my pointing them out
(1) Regularization in QFT has nothing to do with having a cutoff and making an effective field theory. They are issues that are often tangled up with one another, and this seems to really still trip up a lot of people, including the lay community, and even reasonably well trained students. so I thought I’d point that out here. I recommend some of the more modern presentations of QFT (such as Tony Zee’s book) for clarity on this.
(2) There’s nothing wrong with effective field theory, or more generally, effective theory. Arguably, that’s all we ever do in physics and all we’ll ever do.
(3) If string theory turns out to be nothing more than an efficient (and geometrical) way of generating effective theories, then who cares? As long as it helps describe what comes next in the physics that we want to explore beyond the currently known - I’ll take that in a flash.
(4) Combining (2) and (3): The whole “Theory of Everything” business is a red herring. The idea itself might have nothing whatsoever to do with Nature. We’re trying to describe Nature first, and if it turns out that we find a Theory of Everything (I don’t even know what that really means and have doubts as to whether it is anything but a charmingly naive idea) as a bonus, then great…. but the focus is to find how to put together the clues we have to understand nature at the next level. That’s really the best anyone can hope to do at any given point in the development of science. It’s ok to have hopes, of course… and different physicists have different hopes that motivate them. But not all those hopes will be borne out, and new ones will come along.
I made other remarks about Theories of Everything in a blog post here.
Best,
-cvj
JoAnne writes:
“the LHC will not actually be able to determine whether or not the new particles it will discover (note the optimism here) are supersymmetric or not… absolute branching fractions, spins,etc…. are all for the most part out of reach for the LHC.”
I do not think that this occasionally expressed [largely in North America] opinion is entirely accurate. While LHC experimentalists have been largely preoccupied with getting the detectors built and commissioned, and they (and theorists providing support for their groups) have only recently started to do the requisite studies to demonstrate their ability to resolve these issues, the results that they are getting from those studies are much more positive than is often represented. For example take spin determination of candidate supersymmetric partners; on my desk I presently have the following selection of papers:
Barr:
hep-ph/0405052
hep-ph/0511115
Alves, Eboli, and Plehn:
hep-ph/0605067
Athanasiou, Lester, Smillie, and Weber:
hep-ph/0605286
Smillie:
hep-ph/0609296
Wang and Yavin:
hep-ph/0605296
Kilic Wang and Yavin:
hep-ph/0703085
Alves and Eboli:
arXiv:0704.0254
all of which seem to indicate that spins are NOT “for the most part out of reach of the LHC”.
We should also note that these studies are still in their infancy, and will really start developing when there is data to spur interest [for a recent historical example of this effect compare the theoretical predictions of the CMB temperature and polarization anisotropies before , and after, the initial detection of these anisotropies by COBE]. And with colliders it is true that often the final physics reach accessed far exceeds initial expectations; LEP is an example of this where the final precision far (!) exceeded the predictions in the original “Yellow Book” studies. LHC will have a 20 year research program, and the power and level of sophistication of the final analyses may far exceed our expectations today.
———————————————
Samantha writes:
“Although I work in an unrelated field, I have come up with some challenging and contraversial ideas about string theory that are going to upset those in the mainstream.
Unfortunately I have to go out for a bit, so I can’t discuss my ideas right now, but I just wanted you all to know that I know that you are wrong.”
Bravo! I can’t believe that readers here missed this satryical gem! You made my day…..
Thanks!
Reading Peter’s comments in this thread, it seems to me that the question is if string theoreticians consider the prediction of HEP parameters (charges, representations, CKM matrix and masses) as a priority.
I believe that JoAnne’s point is that LHC will not be able to definitely distinguish between SUSY partners and Kaluza-Klein states associated with large extra dimensions.
Eric, I think that Anonymous Cowherd’s point was that the point attributed to JoAnne you mentioned, as well as most similar points in the world, are wrong. And it was not only a point but he also gave you the proof. For a method to distinguish a gluino from a KK gluon, for example, see
http://arxiv.org/abs/hep-ph/0605067
Woit tells us what we want to hear:
I do rather ruthlessly delete comments submitted to my blog that are ill-informed and just add to the noise level, especially the large number from people who think that my blog is a good place to promote their personal “alternative†views about physics.
Ah, but you also “moderate” comments that are aimed to point out the ill-informed ideological dogma of your fellow loopers, whom you allow to take unsupported shots… because “you don’t want it to generate arguments that take away from the subject at hand”.
Course… you’re just as guilty of that as they are, and so your one-sided grunt sessions about the AP are just meaningless neodarwinian-like dogma that doesn’t match the observation, son.
Whoops… I should have said… the “loopers” who support Peter, since Woit is a particle theorist, not a gravity theorist.
As to “Whither String Theory”,
back in March 2004 in a sci.physics.research thread Re: photons from strings? John Baez asked:
“… … has anyone figured out a way to … start with string theory … to get just photons on Minkowski spacetime …”
and there was a discussion among Lubos Motl, Urs Schreiber, Aaron Bergman, et al, and me, that continued in 2004 on sci.physics.strings.
A construction was suggested that started with old-fashioned 26-dim bosonic string theory
and
then using orbifold compactification of 16 dimensions to get 8 first-generation fermion particles and 8 first-generation antiparticles
and
then stacking 8-branes to get an 8-dim spacetime with the Standard Model gauge bosons.
If you look at the 8-branes as representing an 8-dim Kaluza-Klein spacetime a la Batakis (Class. Quantum Grav. 3 (1986) L99-L105), then you may have a string theory model that has a lot of realistic characteristics.
In that sci.physics.resesarch thread, Lubos Motl did not like the model (IIRC, he said it was not supersymmetric and was complicated, both of which are true),
but
kneemo said that it might be “… a nice formulation of (bosonic) M-theory (as Susskind refers to the 27-dimensional theory), from where we work down dimensionally …”.
I attempted to describe it in a paper on the CERN CDS EXT preprint server, where it is available as EXT-2004-031.
Do you think that such an approach might be a reasonable step in linking string theory to the Standard Model, thus refuting claims that all of string theory is “Not Even Wrong” ?
Tony Smith
With respect to my immediately previous comment,
maybe I should also say that, using an 8-dim Kaluza-Klein spacetime (like that of Batakis in Class. Quantum Grav. 3 (1986) L99-L105),
Hashimoto, Tanabashi, and Yamawaki in hep-ph/0311165 calculate, for a Tquark condensate Higgs model, a Tquark mass of 172-175 GeV and a Higgs mass of 176-188 GeV,
thus
making contact with Fermilab collider Tquark results
and
making a prediction for Higgs at LHC,
which
if my immediately previous comment is realistic, establish such contact and prediction in terms of string theory.
Tony Smith
Clifford wrote “The whole “Theory of Everything†business is a red herring.”
Does this mean that the TOE is a theory of Quantum Aquatic Chromodynamics?
e.
Reading such a statement from a string theorist would have been unthinkable some years ago. Maybe the string and anti-string camps are beginning to converge?
Mathematical consistency.
If this is not of value then what is in any theory?
“The Trouble With Physics,†by Lee Smolin, Index page 382, Mandelstam, Stanley, and string theory finiteness, pages 117,187, 278-79, 280, 281, 367n14,15
The discussion with regards to Lee Smolin helped direct our attention to the very last statement made by Lee, to have shown, that an extension was made.
Lee Smolin:
Lee Smolin:
Jacques Distler :
So in principal, “mathematically,” we see where progress is made. Peter Woit had to accept these changes.
Whoa - I take a brief holiday (they do smoke a lot more in Canada, don’t they?)and return to find the teacup as stormy as ever. At a more mundane level zeta function regularisation annoys the uninitiated in almost every field in which it finds application. I used it in the analysis of an interferometric SAR system, and got real grief for my pains. Though (and I hope this is right, Clifford) 1+4+9+16+..=0 does rather astonish. Secure in the knowledge that this stuff is OK with the stringers I can now follow Molesworth and state categorically that ‘eny fule kno that’1+4+9+16+..=0.
Thanks for your support, Anonymous Cowherd. I’m rather busy making tea right now, but when I come back, I’ll clearly demonstrate that, although I am just a lonely voice in the academic wilderness, my aim is just to Make The Madness Stop.
The very basis of science funding may critically depend on my efforts.
Many red herrings seem to be washing ashore these days. Now we learn that computing the electron mass is a red herring, computing the CC is a red herring, and TOEs are red herrings. I dare say that this red trickle was in no small measure motivated by just one piece of experimental data: the observation that the CC, contrary to everyone’s expectations, is positive. And that’s just an astronomical observation.
With a steady flow of high quality accelerator data hopefully soon to appear on line, the red trickle is threatening to become a red tide. I wonder how many red herrings the LHC is going to bring. Maybe even a red whale or two.
Hi Telureo,
You said:
Unthinkabe? Then, with all due respect, you’ve not been thinking very hard, or perhaps you’ve been listening to too few string theorists. Such a statement from an active string theorist (several, I suspect) could have been heard any number of years ago. I’m guessing that you’re confusing the motivations you read about in popular articles written by a few people with the motivations that bring string theorists to work on their research everyday. They do not necessarily overlap. The physics is so rich and varied that there are many many ways of coming to it. The motivation is to describe and understand nature as best we can, not to march along indefinitely with a fixed idea of how we want nature to be. This is the way science has always proceeded. Nothing new there.
Cheers,
-cvj
I don’t know why I do this, but I’m going to comment on these issues again …
Peter argues that string theory has “failed”. For the sake of argument, I would like to stipulate this. It is definitely true that string theory has not yet produced a clear explanation of any aspect of the Standard Model (gauge group, field content, values of any of the parameters), and this is disappointing. How likely string theory is to succeed in this sense in the future (and if so, when) is a matter of pure conjecture, and people differ quite a bit in their opinions in this regard.
So, what is the appropriate reaction to this stipulated failure of string theory?
One possible response is to strike out in a completely different direction. This is Peter’s response; he says he is making “slow progress” in his research. Of course, unless and until this program produces a clear explanation of some aspect of the Standard Model (gauge group, field content, values of any of the parameters), it has the same stipulated failure as string theory. How likely Peter’s program (or any other program) is to succeed in this sense in the future (and if so, when) is a matter of pure conjecture, and people differ quite a bit in their opinions in this regard.
Each individual researcher must, then, make a decision as to the best direction to pursue. The overwhelming consensus at the moment is that the circle of ideas collectively known as “string theory” constitutes the most promising framework. Not everyone agrees, of course, and it may well turn out that some alternate program will succeed. Unless and until that happens, all these arguments will continue to go in circles.
Here’s another point. What if the landscape is correct? That is, our universe really is a “pocket universe” in a vastly larger multiverse that populates a landscape of metastable vacuua in the enormous moduli space of metastable string vacua. Furthermore, the properties of our universe are just randomly selected, with anthropic filtering so that we can be here. And, even worse, there is no particualr correlation among parameters in the landscape, and so no fundamental explanation of any aspect of the Standard Model is possible.
I think this might turn out to be right. If it is right, how would we ever know?
Well, we wouldn’t ever know for sure. Circumstantial evidence in favor would include progress (possibly slow) in better understanding the fundamental, underlying basis of string theory, with clearer and deeper understanding of its mathematical structure and physical possibility. Also, continued failure of all other programs to do any better, and lack of progress in better understanding the fundamental, underlying basis of each alternative program, or the inability of alternate programs to clearly reproduce the Standard Model plus gravity as an effective field thery.
That would be disappointing, of course. It would make physics a lot more like most aspects of human life, where conclusive proof of anything is awfully elusive. But people like Peter seem to have an underlying notion that this scenario is not just unpleasant, but actually impossible, that there must be a fundamental explanation of the parameters of the Standard Model, and that any research program that looks like it’s going in the opposite direction should be dropped immediately.
This is an ideology which is, in my view, inherently unscientific, since it assumes a result (that there is a fundamental explanation of the parameters of the Standard Model) that is, in fact, still very much open to legitimate scientific doubt.
Mark,
I think I’m repeating exactly the same argument I’ve made many times before, and you don’t seem to have paid attention to it any of those times, but here it goes again. I don’t think it’s actually substantially different than the one David Gross and Paul Steinhardt are making on the issue of the anthropic landscape. You might want to try stopping by Gross’s office, telling him that he’s promoting an ideology that is unscientific, and arguing the issue with him.
I have nowhere said that the landscape scenario is “impossible”. It’s a logical possibility. But there are lots of logical possibilities that can’t be scientifically investigated. It’s a logical possibility that we are a simulation created by higher beings, and the only explanation of the standard model parameters is that those being chose them, for reasons we can never know. It’s a logical possibility that standard model parameters are all environmental, and we can’t ever explain their values, since they come from some earlier history we have no access to.
For a hypothesis to be scientific, it has to come with some way it can be convincingly tested, at least in principle. This is what the whole argument here is about: do the people promoting the anthropic landscape have a plausible argument for how to convincingly test this scenario experimentally, even in principle? If they do it’s science. If they don’t, they are scientists engaged in pseudo-scientific argumentation. I’ve read the papers of the people making these arguments very carefully, and at length on my blog and elsewhere have argued that:
1. The only testable predictions you can hope to get out of the anthropic landscape are the statistical ones that predict that we will see values of that are not far out in the tails of probability distributions. There’s no anthropic reason for the proton lifetime to be as long as it is, and there is no plausible argument I know of that says that string backgrounds should conserve baryon number. The observed value of the proton lifetime is very far out in such a tail. This prediction has flat out been falsified.
2. The string theory landscape is a classic example of scientific failure. Often scientific ideas fail not because they are rigid enough to make predictions that are falsified, but because you can get almost anything you want out of them by adding in more and more complicated structure. Simple versions of the idea don’t work, people look at more and more complicated versions, until the whole thing collapses of its own weight. This is a very common form of failure of a research program, and it is what has happened here. The only thing unusual is the lengths people are going to in order to avoid admitting this.
Paul Steinhardt in the discussion at http://www.edge.org that is up now makes precisely the points I am making: the anthropic landscape is not a valid scientific research program, it is what he calls one that has “crashed”, i.e. failed definitively.
As for whether the “overwhelming consensus” of the physics community is that string theory is the most promising thing for people to be working on in order to make progress towards unification, I just don’t think this is true, and it’s also not especially relevant, since science is not a popularity contest. During the 1960s the “overwhelming consensus” was that QFT could not describe the strong interactions, but it was wrong. If you restrict attention to people working on string theory, sure they may have an “overwhelming consensus” among themselves but I think that a very significant portion of the particle physics community doesn’t share in this consensus. Many, many of them think that string theory unification is an idea which has been tried but hasn’t worked out, and now shows every sign of conclusive failure. I don’t have any numbers on this, it would be interesting if someone could figure out how to gather them in a sensible way. If this had been done over the past twenty years, I don’t know what the absolute numbers would have been, but I am quite sure that the time derivative is negative, and if you extrapolate to the future you’ll find this “overwhelming consensus” disappearing if it has not already done so.
Re: Posts #51 and #52
Dear Mark
Thanks for the insightful analyses, clearly articulated. But are you sure that you really want to be doing this again? The vitriolic attacks that seem inevitably to blight any blogosphere discussion of the present state of theoretical physics, seem to be driven by hostile feelings on the part of the critics, towards the research programs of others. It seems to me unlikely that any manner of reasoned argument will persuade people who seem to have so much emotionally invested in the prospective failure of other peoples’ research.
In this regard, it seems to me that Wiitten’s approach is the wisest; stick to the physics and don’t get distracted by noise on the internet. [Feynman famously put it more bluntly: "shut up and calculate"]. My general observation is that people are most inclined to spend time criticizing others’ research, when they are unhappy with the progress of their own; to waste time debating them risks reducing your effort on your research to the level of their effort on their research. I’m sure that you have better uses for your time.
Remember: “living well is the best revenge”.
Anomalous, I personally find much more vitriol and hostility in post #54 than in #53, and more reasoned argument in #51—#53 (and some others above) than in your posting immediately preceding this. Whether the reasoned argumentations presented there are correct or not is a different story. But that’s what reasoned argument is for, isn’t it? To try and find out which arguments hold water and which don’t.
Regardless of whether or not the anthropic landscape is true, if string theory is correct then there should be at least one string vacuum which can produce all physics in our univserse in complete detail. Even if we have no idea why such a vacuum is chosen by nature, it still seems to me that finding it would allow us to understand everything about the universe we live in. Conversly, if we find such a vacuum it may have some special properties which may lead us to understand why it is chosen. It may be that part of Woit’s complaints about string theory is that some in the community may feel that it isn’t necessary to explain physics that is operative in our universe, and these people are resigned to the antrhopic principle.
#53
“There’s no anthropic reason for the proton lifetime to be as long as it is, and there is no plausible argument I know of that says that string backgrounds should conserve baryon number. The observed value of the proton lifetime is very far out in such a tail. This prediction has flat out been falsified.”
Folklore has it that in the 1960’s Maurice Goldhaber argued for a lower bound on the lifetime of the proton of order 10^24 years from the fact that we don’t die from the health effects of radiation from decay of protons in our own bodies and our environment [the phrase that I heard attributed to him was that we feel the longevity of the proton "in our bones"]. Limits on ambient proton decay radioactivity may be even more stringent from survival of RNA and DNA when life started in the primordial ooze on planet earth [I don't know enough biology/biochemistry to quantify this]. Are you so confident of your mastery of primordial biology that you can convincingly argue that this is hierarchically shorter than the proton lifetime limits from Super-K, which for the decay modes induced by the dominant dimension-five operators are of order 10^32 to 10^33 years? If not, then this could actually be argued to be a successful prediction of anthropic reasoning, rather than a prediction that has “flat out been falsified”. I wouldn’t make that argument personally, but it seems to me that your counter-argument is at least as suspect.
There is no “prediction” of the proton lifetime from the landscape that has been “falsified”. (Peter likes to insist, on the one hand, that string theory is incapable of making predicitons, and, on the other, that it has already made predictions that have been falsified.)
As of now, we have no idea what features are or are not common to landscape vacua (if any) that reproduce the Standard Model to sufficient accuracy. It may well be that, in all or almsot all such vacua, all baryon-number-violating effects arise only at the unification or the string or the Planck scale, which would make it within experimental bounds. In fact this seems to me to be the most likely possibility.
Eric, I agree completely that finding one string vacuum that matches the Standard Model would be a good and important thing to do. Experts tell me that this is a daunting task, and that they need better tools to be able to do it without extensive trial-and-error constructions.
Eric said “… if string theory is correct then there should be at least one string vacuum which can produce all physics in our univserse in complete detail. …
Conversly, if we find such a vacuum it may have some special properties which may lead us to understand why it is chosen.
It may be that part of Woit’s complaints about string theory is that some in the community may feel that it isn’t necessary to explain physics that is operative in our universe …”.
The model in my comments above (42-43 in the present numbering) might show how to construct “at least one string vacuum which can produce … physics in our universe …”,
so
it is hard for me to understand why string theorists are not interested in exploring it in detail, especially since no one has yet shown it to be fundamentally flawed,
unless
it is true that “some in the … string theory … community may feel that it isn’t necessary to explain physics … “,
which would be sad for the future of theoretical physics.
Tony Smith
In fact, some string theorists think that it is a red herring….
Anomalous Cowherd,
I don’t think you’re making any sense at all. If you have any ideas for an “anthropic” explanation for the proton lifetime, I suggest you publish as soon as possible, since many people will get very excited by it and you will immediately become a leading figure in the hottest field of particle theory.
Mark,
The argument I’ve given here can’t be news to you, I’ve made it many times on this blog and others, I think more than once in direct response to you. I think there are legitimate arguments that statistical “predictions” from the landscape can’t actually be sensibly made. My point is that these are the ONLY possible arguments, whether or not they work. You have two choices: assume they don’t work, then you can never predict anything, or assume they do work, then you get wrong predictions. My guess would be that they don’t work, but my point is that if you stipulate that they do, you get wrong predictions.
If you have a serious argument for why the anthropically allowed part of the string theory landscape has to have proton lifetimes at or above the current limits, I make the same suggestion to you that I make to Anomalous Cowherd. Go ahead, publish, and become a leader of the field….
Anomalous Cowherd,
Your number of 10^24 years for the Goldhaber argument didn’t sound right to me, so I just checked it. All other sources give it as 10^16-10^17 years.
I suggest that you very seriously consider stopping posting anonymous comments here, and put your name and reputation behind what you have to say. Doing so might encourage you to take some care to not make obviously false claims.
Peter, you can’t know whether the predictions work until you know what they are. While there are many speculations as to what the predictions might be, there are as yet no firm results. So your statement that “you get wrong predicitons” has no evidence whatsoever to support it. In particular, your claim that if the string landscape makes any predictions at all, then it gives an incorrect prediction of the proton lifetime, is flatly wrong. As I explained above, it’s entirely plausible that any vacuum that has a global symmetry (like baryon number conservation) in the low-energy effective field theory has that symmetry violated only by effects at the string or Planck scale; this would predict a proton lifetime that satisfies current bounds. But we don’t yet know if this speculation is right or wrong. More work needs to be done to find out.
Thanks Mark for making clear the points we need to consider in face of what is constantly being bombarded by “other points of view.”
Tony Smith-
On condition that we accept what?
This is what is being portrayed as “being irresponsible,” while it is obvious such statements can serve to make the whole research avenue in string theory hopeless and “fruitless”:) E8’s flowering attributes…hmmmm….:)
“This method” is a continuing aspect met by “setting the conditions for acceptance,” while it is obvious that “Mark’s point of view” says otherwise.
The arguments should “set the parameters” and not be then subjected too the schism of thoughts about one’s “personal opinion.” One can support and bias opinion by what they then censor. It becomes a pretty clear picture from then on. Carries a certain “tone” to it:)
Then the public gets a “clear message” of the resulting area of research in the face of a personal opinion.
Mark:
Layman asking.
What kind of tools? Is not “mathematical construction” not important for that perspective in regards to Genus development, and “correlative development(?)” of that one string vacuo?
Mark,
The argument you need to make is not that if a string background looks exactly like the SM at observable energies then baryon number violation will be suppressed statistically. You need to show that among all the possible string theory backgrounds that are anthropically allowed, ones with baryon number violation are statistically suppressed by a huge factor. If you actually look at classes of backgrounds that people study, this just isn’t true (except to the extent that, within a class, they only look at phenomenologically viable ones, e.g. by picking out ones that look like then SM and have a desert, in order to avoid having any non-SM effect actually be observable…).
Just a trivial point.
The idea that the longevity of the proton falsifies the anthropic principle hasn’t been found by Mr Woit but by Banks, Dine, Gorbatov in 2004
http://www.iop.org/EJ/article/1126-6708/2004/08/058/jhep082004058.pdf
Leonard Susskind replied to it here:
http://arxiv.org/abs/hep-th/0405189v1
Dear Peter,
Intersecting brane worlds are one of the large(st ?) class of models people study in building Standard Model-like models. The QCD brane carries a U(3) gauge group, the SU(3) becomes QCD and the U(1) is baryon number. If the U(1) is anomalous then baryon number survives as a global symmetry (and at high energies is a gauge symmetry). Therefore from a model-building perspective, having baryon number as an exactly conserved global symmetry is really quite easy.
piscator
Anonymous hero,
I wasn’t claiming priority on that argument, thanks for pointing to the Banks, Dine Gorbatov paper, which I should have mentioned since that’s where I first heard this argument. Susskind doesn’t actually address the proton lifetime problem, he just addresses the assumption by Banks, Dine, Gorbatov that supersymmetry is broken at low scales. He points out that landscape statistics may actually predict breaking at high scales, not low, but the fact that even this can’t be resolved is good evidence that landscape statistics can’t predict anything (this should be about the easiest case). If you take Susskind’s argument seriously, if the LHC sees supersymmetry, then Banks, Dine, Gorbatov works, so the Landscape is dead. Steinhardt makes the point in his edge discussion that no one is taking these arguments seriously, just modifying them as needs be to make sure that the Landscape never can be falsified.
Piscator,
I’m not saying you can’t construct models that preserve baryon number, just that, if you start counting anthropically allowed models (despite the fact that there probably is no consistent way to do this counting), there’s no reason for baryon number conserving models to be suppressed in the count by the huge factors that would be necessary.
By, the way, I think people being willing to engage in a serious discussion of these issues is great and I’m happy to participate, but it’s kind of annoying not knowing who one is talking to….
It’s really quite amusing watching Peter Woit attempting to play both sides of the street (The landscape renders string theory inherently unpredictive about particle physics at accessible energies and, in nearly the same breath, The landscape yields predictions which have already been falsified.). Since I’ve already rebutted the former (see also the followups: I,II,III,IV,V,VI), I’ll leave it to others to rebut the latter.
Plato quoted me as saying
“It is true that “some in the … string theory … community may feel that it isn’t necessary to explain physics … “,
which would be sad for the future of theoretical physics.”
and then asked
“… On condition that we accept what? …”
The quote of me by Plato was from my comment 59 here, in the context of the failure of string theorists to evaluate a model (see my comments 42 and 43 here) that may connect string theory with physical reality
and
was constructed in a discussion in 2004 on sci.physics.research and sci.physics.strings, so the details of its construction are open on the web for everybody to study.
The only criticism I have received of the model was from Lubos Motl, who correctly noted that the model is not conventionally supersymmetric and is complicated.
I do not consider either to be fatal flaws.
My criticism is of
1 - the lack of interest by the string theory community in a model that might show how string theory is connected to physical reality and
2 - the fact that I am blacklisted by the Cornell arXiv and so prevented from writing about the model there.
I suspect that 1 and 2 are not unrelated to each other.
Tony Smith
dear Peter,
i meant something a bit stronger than that one can construct models where baryon number conservation applies. in the intersecting brane setup, it’s hard for it not to apply - a stack of three branes always carries a U(3) gauge symmetry, which includes the U(1) of baryon number. this doesn’t hold for lepton number since then su(2) can be sp(2) without an extra U(1) factor to complete to u(2). anyhow, the existence of perturbatively conserved baryon number seems quite natural. I have no idea what a probability measure on the landscape would look like, but if I did I would expect two delta functions, one for which the proton decays very rapidly and one for which it never decays.
on anonymity: there are perfectly good reasons for it, and I prefer it. If I write a paper I spend months ensuring that I am happy with what I am writing. If I am commenting on a blog I spend minutes. There is a lot of overlap between axiv and blog readership; i’d rather be judged by what i contribute to the former rather than the latter.
piscator
Jacques,
You seem to have trouble following an argument that has more than one part to it, but I really think you should concentrate and try. I wrote out clearly an argument here that doesn’t fit in one phrase of a sentence, see if you can follow it.
I also think you should consider exercising some more self-restraint in the area of html tags. I guess the bold-facing of phrases is supposed to indicate that they are my views, probably even quotes from me. I know you’re very fond of taking things I write out of context, often changing the wording, then putting the result in between quotes, then using it to sneer at what an idiot I am, a fool who makes arguments that are easily demolished. Your use of bold-face seems to be a variant of this. I think you should stick to the quotes, it’s a standard convention.
piscator,
You’ve explained well why anonymity is convenient: you can make arguments without worrying that they’re uninformed or dumb, and thus would reflect badly on your reputation. This still doesn’t explain why you think it’s either ethical or professional behavior.
So, is your claim that string backgrounds predict (perturbatively) exact baryon number conservation? According to you string backgrounds either have fast proton decay (not seen), or no proton decay. So, if experimentalists see a proton decay, that means string theory is falsified?