The LHC media blitz is in full swing, with last week’s long New Yorker article now followed by an unusually long and detailed New York Times piece titled A Giant Takes On Physics’ Biggest Questions. Dennis Overbye does an excellent job of covering the story. Besides the experimentalists actually involved in building the machines, he quotes theorists John Ellis, Joe Lykken, Nima Arkani-Hamed and Michelangelo Mangano. To distinguish this piece from the New Yorker one, here it’s Mangano who is the one who consumes a lot of espresso. There are side-bars about the recent problem with the Fermilab magnets and about the implications for string theory (not much). There’s a multimedia component to the Times coverage, with interactive graphics, a slide show, a podcast (an interview with Arkani-Hamed, described as “one of the physicists at the center of the project”), and a video.
I do fear all this LHC coverage is peaking too early. With still probably at least a year to go before the machine even starts taking data, the coverage may already be generating an LHC overexposure problem: see Chad Orzel’s new posting Tired of the LHC. If Chad is already complaining about this, boy is he going to be grumpy about it by a year from now…
The New Yorker keeps its physics theme going this week with cover art that includes a blackboard full of basic equations from quantum mechanics.
The NY Times article includes the usual not very cogent explanation of the role of the Higgs. For something much better aimed at explaining Higgs-hunting to the general public, see the online interactive presentation Hunt for Higgs, part of a web-site about the LHC called Big Bang.
Blogging may be light the next week or so since I’ll be traveling. First stop is Trieste, where I’ll be speaking at 5pm on Friday as part of a large event there called FEST. From there I’ll make brief visits to Geneva, Paris and London, back here in New York late next week.
All the better to hype it now and give it as much coverage as possible, as when it’s running a year or two from now it’ll probably end up finding nothing useful anyway.
Then again, maybe some LHC hype makes it possible to collect some money for a few other projects while LHC is still being built..
Maybe the notion of “useful” has been blurred by calling the Higgs boson “God particle”, and string theory the “Theory of Everything”. Those suggest that nothing short of finding “God” or “Everything” is good enough.
I think discovery of, at least, new phenomena related to the EW interactions is guaranteed (by the usual arguments). Whatever is found, even if it’s “just” the SM Higgs, will be a Real Natural Phenomenon (TM), infinitely more useful than any speculative fantasy about gods and everythings.
I think its likely that within two years, the particle physicists and string theorists will be sipping champagne, and all of the stupid people who think it will find nothing will dissappear into the vacuum.
It’s rare you see such a pure expression of bravado outside of sports bars. Like: I think it’s quite likely in two years the Philadelphia Eagles will have won two Super Bowls, and all the stupid Patriot and Colts fans will disappear into the vacuum.
Walt,
Physics isn’t sports. The people who doubt that LHC will find anything, don’t do so for rational reasons. They actually hope it won’t. The overwhelming liklihood is that there will be significant discoveries.
I think you two should put some money on this.
How can anyone seriously say whether or not new phenomena will be found at the LHC?
Really, how? Either way it’s “faith” based.
Now saying string theorists will be sipping champagne is another thing since I would like to know of a possible discovery that would legitimately justify that. Just an example.
The string theory landscape is so big, they probably will be sipping champagne in two years whatever the LHC discovers, because they will be able to pick out a vacuum which resembles the physics, whatever that physics turns out to be.
That’s the whole brains of string theory! Whatever nature turns up, it’s impossible not to come up with some version of string theory which can include that. String theory predicts everything remotely possible, so we it is right before doing the experiments. The experiments just help us identify the correct model. I can’t understand why people (apart from Prof. Anti-Crackpot) don’t understand.
Physicists can start celebrating string theory now, because it can’t be falsified, there’s no sensible alternative with as much hype as string, and even if there was a fashionable ‘sensible’ alternative, it would be likely to be extremely boring compared to the 11 dimensional 10^500 models of the string multiverse.
Plank,
If we weren’t able to seriously say that there’s a strong liklihood of discovery, LHC would not have been funded. The Higgs and supersymmetry will both likely be discovered. They are both well-motivated theoretically. You should understand that these are not just things theorists invent because they’re nice. These are really necessary pieces that need to be added to the Standard Model.
These are really necessary pieces that need to be added to the Standard Model.
The Higgs or something else to unitarize WW scattering, yes. Supersymmetry, no.
I don’t understand this discussion about the LHC. Surely it will find new phenomena, irrespective of whether they can be related to string theory. in some sense, failure to find a Higgs boson in the expected energy range would drive high energy physics forward even more strongly than would the confirmation of a mass within the currently favored limits. Either result would be great.
High energy physics is presently unbalanced between theory and experiment, and in serious need of experimental data in new energy regimes. *That* the LHC will provide one way or another.
Anon,
If there is a Higgs boson, then supersymmetry is essentially required to to stabilize the Higgs mass, otherwise known as the hierarchy problem. There may be other ‘solutions’ to this, but none of these is natural. The existence of supersymmetry is probably just as necessary as the existence of anti-matter, as a necessary symmetry of nature.
It seems to me that there’s been a curious drift in the rhetoric on this blog of late. It looks to me like SUSY is being taken as synonymous with string theory, which it’s not (the latter clearly requires the former, the reverse is not true). SUSY is theoretically well-motivated and quite predictive. It should be possible to rule SUSY out with future experiments, unlike string theory. So why is everyone so pissed off about SUSY?
observer,
I seriously considered deleting just about all the comments on this posting. Our string-theorist troll “Anti-Crackpot” generates lots of content-free responses. Please, no more of this on both sides. In general please resist posting contentless comments that do little except aggressively express an opinion, without even bothering to justify it.
Sure, SUSY is better motivated and more predictive than string theory. But I think there recently has been a reaction to the fact that SUSY has received and continues to receive an overwhelming amount of attention, despite the fact that SUSY scenarios are far from convincing (generally due to the fact that SUSY-breaking leads to all sorts of trouble). Many SUSY proponents way back when vigorously claimed that evidence for it would show up at the Tevatron. The fact that that didn’t happen, and that effects also haven’t shown up in precision electroweak data, I think has caused a lot more skepticism about whether it will be seen at the LHC.
But, it is very different than string theory, will get a real test at the LHC, and we’ll find out one way or another within a few years. If the LHC sees nothing, the idea that supersymmetry stabilizes the electroweak scale will be conclusively dead.
«These are really necessary pieces that need to be added to the Standard Model.»
OK, suppose both are discovered beyond reasonable doubt. In what way does that corroborate String Theory?
Neither of those ideas were created in a String context, or am I wrong?
If there were some specific predictions from ST regarding SUSY breaking or the higgs mass I could understand, but to my knowledge there is nothing serious close to this.
So my question stands, what should be discovered at the LHC in order to justify string theorists “sipping champagne”?
And what would justify its demise.
These are important questions that should be answered *before* the actual data is analyzed, otherwise I’m afraid anything will be hailed as a victory for ST.
Since almost anything the LHC is likely to find will be shown to be consistent with string theory, I predict that the string theorists will be sipping champagne three years from now, no matter what the LHC finds.
Peter,
I could reply to your insult about being a string-theorist troll, but let’s not go there. Let’s leave that for Lubos. I’m really more of a particle physics person than a string theorist.
My opinion on the reason for the sentiment against supersymmetry on your blog is that it is due to the fact that it is a necessary component of string theory, which you strongly disfavor. Otherwise, it’s hard to understand why anyone would be so against it., especially since it’s well-motivated theoretically and testable. It seems to me that there is a strong current against mainstream particle physics on this blog, and I feel I must go against this.
Plank,
String theorists will be happy if supersymmetry is discovered because it is a necessary part of string theory. Don’t forget that SUSY was actually discoverd in string theory first, before being formulated in normal particle physics by Wess and Zumino.
Anti-Crackpot,
My opinion about supersymmetry in general is mixed, there are many things interesting about it. As for the MSSM, I’ve always been a skeptic, even back pre-1984 when string theory became popular. There’s a whole chapter in my book about the problems with supersymmetric extensions of the standard model, this is an issue independent of string theory.
I’m getting really sick of the contentless bickering here. Please, all parties stop. Comments containing zero information, just some an expression of opinion backed by at best best a vague, tired talking point will be deleted. I can’t believe anyone is getting anything at all from this kind of discussion, other than the idea that reading the comment section here is a waste of time.
Anti-Crackpot,
Wasn’t SUSY first discovered around 1970 by Likhtman and Golfand?
Peter,
I’m not sure that there has been much bickering in this thread, or that the posts have had zero content. If you don’t like people disagreeing with you then perhaps you should shut down the blog altogether. Perhaps my statement about the ‘stupid people dissappearing into the vacuum’ was a little harsh, and I apologize.
As for supersymmetry, it’s fine to be skeptical. The main point I want to make is that the subject is one that should be taken seriously and not just be dismissed as the musings of idle string theorists, whether or not it turns out to be right or wrong.
JC,
Yes, it may have been, but if I remember correctly they were in the Soviet Union at the time, so noone in the west knew about their work.
Don’t forget that SUSY was actually discoverd in string theory first, before being formulated in normal particle physics by Wess and Zumino.
When and where?
Coin: Ramond, Schwarz, and Neveu in about 1971-1972.
Anti-Crackpot: I don’t know if supersymmetry was first invented by string theorists or by communists, but surely the discovery of supersymmetry would not imply that communism is right nor that string theory is right.
The reason why LHC is interesting is not that we know that LHC must discover supersymmetry, but that we do not know what LHC will find, and exploring higher energies is the only way of sorting out physics at higher energies. Even if LHC will tell that we lost decades on a wrong idea, it will be progress, and this is why I prefer to work on testable weak-scale physics rather than on quantum gravity.
Peter Woit wrote “But, it is very different than string theory, will get a real test at the LHC, and we’ll find out one way or another within a few years. If the LHC sees nothing, the idea that supersymmetry stabilizes the electroweak scale will be conclusively dead.”
Hello Peter, if LHC does not find SUSY-partners, and yes I’ve read your book NEW cover to cover, and therefore does not stabilize the electroweak scale, it doesn’t seem to me that there’s no compelling reason (other than string theory hype) to continue to pursue this as serious research. In otherwords, if SUSY doesn’t stabilize the elctroweak scale, while SUSY can be broke all the way up to the planck scale, there is no reason to believe it is a symmetry of nature if there is a LHC null result. (Presumably the theoretical difficulties of breaking SUSY and flavor changing neutral currents and large CP violations others in combintation to a LHC null result should pretty much discredit the theory).
M,
You’re right that the discovery of supersymmetry would not prove string theory. However, since SUSY is a necessary ingredient, it would certainly suggest that string theory is in the right direction.
The discovery of SUSY might suggest that string theory moving in the right direction. But that’s not the issue, is it? The problem is that the failure to discover SUSY wouldn’t disprove “string theory.” Apparently, that’s impossible!
Michael,
The honest truth is that if SUSY is not found at LHC, most interest and support of string theory will completely evaporate. Unless, of course one of the large extra dimensions/ brane world scenarios turns out to be true. In that case, there will be KK states and black holes galore, and string theory will be experimentally confirmed.
The honest truth is that if SUSY is not found at LHC, most interest and support of string theory will completely evaporate.
Nonsense — you can find plenty of string theorists who claim that high-scale SUSY breaking is actually favored, or at least not disfavored. It’s not at all clear at the moment what string theory has to say about what is likely at the TeV-scale.
Also, above:
then supersymmetry is essentially required to to stabilize the Higgs mass, otherwise known as the hierarchy problem. There may be other ’solutions’ to this, but none of these is natural.
Again, nonsense; technicolor is natural, for instance. It just happens to be highly disfavored by precision data. There is also the possibility that the Higgs mass is simply tuned. There is absolutely no argument that SUSY is “required” or “essentially required” by the SM. There are only debatable aesthetic or philosophical reasons for liking it.
Anon,
Sure, it’s always possible that the SUSY breaking scale will be high enough that the superpartner masses will be unobservable at LHC. However, then SUSY would not be able to solve the hierarchy problem, and so would lose much of it’s justification. If this happens, I don’t think people would take SUSY seriously, regardless of what ‘plenty’ of string theorists say.
I don’t think that technicolor is particularly natural. Besides the fact that it doesn’t work, it has always seemed rather ugly and contrived to me. On the contrary, supersymmetry solves the hierarchy problem, gives us gauge unification, and provides a dark matter candidate. Keep in mind that supersymmetry was not originally invented to solve these problems. This is what I would call natural. The fact remains that something beyond the standard model is required and supersymmetry is the best bet for that somethting, by far. Thus, all of your statements are complete nonsense!
Hi Peter,
Peter, you clearly have little beyond trivial knowledge of what physics is really about… I have come across only ONE! paper by you in the last upmteen years that was worth reading through (‘Particle Physics and Representation Theory’). Clearly you spend way!! too much time trying to be critical of theories you have already decided upon are unworthy of further study… and yet you continue to quip over and over on them… sigh!
If you are genuinely a physics researcher you would engage in one of the following activities:
1. Doing physics research… of whatever kind there is to be done… (i.e. in condensed matter theory, astrophysics, biophysics, chaos theory, etc.);
2. Writing up beautiful notes for Weinberg’s QFT texts and distributing them freely on the net;
3. Doing both with one hand tied behind your back.
Regards,
Mikka
4
Anti-Crackpot Says:
The fact remains that something beyond the standard model is required…
The false assumption being that the resolution to the problems can’t possibly come from something fundamental that was missed along the way.
I beg to differ.
On this question of distinguishing supersymmetry from string theory stuff, I thought that ‘superstring’ is an abbreviation of supersymmetric string theory, and since M-theory unified the five theories in 1995, string is in effect synonymous to superstring?
Many string predictions are supersymmetry predictions: unification at 10^19 GeV, s-particles with unpredictable energy, etc.
I don’t see how any experimental result will be able to confirm or deny supersymmetry or string predictions.
By the time you have enough experimental data to be meaningful, you will have resolved the problem experimentally. What use is theory in that case? Dirac predicted the energy of antimatter particles, Pauli predicted the energy of neutrinos, and the Standard Model predicted the energy of weak gauge bosons. There’s nothing like that kind of prediction from string/supersymmetry. String is a great theory for yellow bellies, scared of experimentally refutation.
anon, Anti-Crackpot,
If string theory ever falls out of favor in physics departments, it will most likely still be pursued in math departments. Some areas of string theory have very interesting mathematics (ie. mirror symmetry, etc …), that some mathematicians would still be interested in.
On the other hand if supersymmetry is not seen at the LHC, it wouldn’t be surprising to susy phenomenology fall out of favor and eventually die shortly thereafter. Though possibly some hardcore SUSY true believers will still work on it. Analytic S-Matrix theory falling out of favor in the early 1970’s, didn’t stop Geoff Chew from continuing work on it well into the 1980’s.
“If” susy is found… “if” KK states are found… “if” substructure is found… Those are some big “if”s. The bottom line is that physics at the TeV scale is going to be experiment-driven. With exactly zero predictions, theory has lost the LHC train.
I stumbled on your website, trying to find information about a theory about gamma ray bursts that has been written up in general interest publications, such as the Economist. I am a layman (although with a scientific background — chemistry), but I have a paranoid interest in particle physics.
The theory that I was wondering about was Dr. Clavelli’s theory that GRBs are produced by a spontaneous SUSY transition in white dwarves. From what I understand, GRBs are generally thought to be caused by exploding stars, and if anything, GRBs tend to not occur in galaxies where there are not very many elements heavier than helium, which seems to negate this idea. I was wondering whether Clavelli’s ideas (regarding GRBs and spontaneous SUSY transitions in general) are taken very seriously in the physics community as a whole.
L-Train,
Cosmic Variance would be a better blog for you to monitor, given your apparent interests. It also links to other blogs that focus on astrophysics.
Sinus,
Supersymmetry makes a very specific prediction: for every Standard Model fermion, there is a corresponding boson. If these states are discovered, then supersymmetry will be confirmed. We cannot at this point make specific predictions about the mass and mixings of the supersymmetric specturm because we can’t say exactly how SUSY is broken. However, if SUSY is to explain the hierarchy problem, then the states must be TeV scale.
Anti-Crackpot: You are clearly offended by the existence of skeptics. Whether or not SUSY is confirmed, would physics have been better off if there were no skeptics? Clearly not.
Walt,
What offends me is skeptics who spread misinformation.
What offends me is skeptics who spread misinformation.
So the landscape dwellers who are certain without hope of solid confirmation that there are 10^500 universes each with 6/7 extra dimensions curled up in different versions of the Calabi-Yau manifold, don’t offend you? Bullshit with the stamp of mainstream consensus is inoffensive, while objections from skeptics of the mainstream which contradict the mainstream claims are offensive misinformation? Quite right too!
Maybe you need to increase your ability to take offense, however. Be also strongly offended by people with alternative ideas. That’s spreading misinformation, if the ideas don’t fit into the mainstream consensus, the superstring framework. One other thing to take offense from (when you get more sophisticated): experiments. Experiments are just an embarrassment to an irrefutable theory.
Hello Peter,
sorry for dribbling most of this nonsensical thread about who believes what and why it is stupid to/not-to 😉 My comment is rather about the point made in the post, i.e. that there is an over-exposure of the LHC quite a bit too early.
There are physicists who have spent the better part of their last 15 years designing, building, simulating, testing, assembling the giant detectors that are now almost ready to take data. These people have invested maybe half of their career in the project. It is them who will arrive tired to the first day of data taking, unfortunately. These experiments are really too long shots in this respect. However, I really see no alternative, but can only hope that the next efforts will be based on more readily available technology and funds, such that the hiatus between the TDR and the data becomes more reasonable.
I agree, the media are overhyping an endeavour that is either too old or too young to be meaningfully in the headlines. It is now clear that LHC will have no chance of having produced enough data to see the Higgs boson before mid 2009. And even SUSY particles, which some simple minds believe will pop into view the moment the detector is turned on, will have to wait until then to be discovered, if ever.
My two pence ? The LHC is getting its share of spotlights because now is the time to start financing its upgrade, the SuperLHC. Projects on R&D for detectors to be installed in CMS and Atlas to sustain 10^35 luminosities are already under way…
Cheers,
T.
PS have fun in Trieste, and stay away from Casinos in Slovenia!
Bitter much?
Anon,
I don’t think that I’ve been making an argument for string theory or the landscape. My arguments have been strictly in favor of SUSY. It is quite possible for the world to be supersymmetric and string theory to not be right. As far as skepticism is concerned, I’d like to hear real alternative ideas rather than just arguing against supersymetry on the basis that we haven’t yet observed the SUSY partners. If LHC does not observe them, then your skepticism will be justified and shared by many particle physicists. However, we know that the SUSY scale should be 1 TeV or less to solve the hierarchy problem, so there’s no point being skeptical until the range of energy has been explored.
At the risk of feeling like I’m banging my head against a brick wall, let me point out some things that seem to be misconstrued or not known by at least some of the people discussing this here:
1) It would be nice if the hierarchy problem turns out to have a solution. On the other hand, it might not; the universe might just be described by a fine-tuned low energy effective field theory.
2) SUSY does solve the hierarchy, as does technicolor (whether you think it looks “natural” or not, it certainly is technically natural). Technicolor is highly disfavored by precision data. SUSY is also disfavored by precision data, just less so. (This is called the “little hierarchy”.) You can’t think seriously about TeV-scale SUSY models without running into LEP data. There is no beautiful model that can solve the hierarchy problem, fit the data, and that doesn’t have some ugly kludges and/or fine-tunings built in somewhere.
3) There is a nice model that has gauge coupling unification, dark matter, and no real difficulties with precision constraints. It’s called split supersymmetry, and it does not solve the hierarchy problem.
4) String theory does not have much of anything to say about whether there is TeV-scale SUSY at this point. There seem to be lots of vacua with high-scale SUSY breaking. There are some approaches that claim to favor TeV-scale SUSY (e.g. claims that M-theory on G2 compactifications tends to have TeV-scale SUSY breaking once the cosmological constant is tuned to zero), but there doesn’t seem to be any reason the theory would prefer those vacua.
Anti-Crackpot,
seems there was quite some indoctrination going on during your scientific education.
If you had ever deeply thought about 4D Yang-Mills and its relation to real physics (meaning ideas, concepts and quantitative predictions that are experimentally falsifiable) you would have had your answers concerning alternatives to the present doctrines for solving the hierarchy `problem´.
I wont react on any of your comments.
Anon,
I don’t really understand why you are so upset. I only make the well-known point that supersymmetry is currently the best candidate for new physics and that it is clearly testable. I do not claim that it’s the only possible solution, only that it’s the most plausible solution. As for string theory, I guess I need to repeat that my arguments in favor of SUSY have nothing to do with string theory.
r hoffman,
I have a Ph.D. in theoretical physics, having learned from some of the very best particle phenomenologists and string theorists in the world. I think I know what I’m talking about it and have no trouble with your empty statements.
It is quite possible for the world to be supersymmetric and string theory to not be right. … I’d like to hear real alternative ideas rather than just arguing … – Anti-Crackpot
Well, your pseudonym doesn’t encourage me to believe your claim about wanting to hear ‘real alternative ideas’. String and SUSY have had 25 years of mainstream support to work out the details. The common problem with any alternatives is that they are haven’t had 25 years of mainstream funding, interest, and development. So you’ll be able to dismiss them by definition as non-mainstream, for being less well investigated than string and SUSY. There are several real alternative ideas but this blog is not a free for all discussion of them. The question is, if you’re an anti-crackpot, why are you so keen on invisible superpartners which increase the tunable Standard Model parameters from 19 to 125 or more, without delivering any useful additional predictions in return.
The worst type of physics is that which like phlogiston, a wonderful solution to why burned things weigh less than unburned things, but is always totally useless for quantitative predictions, and finally turns out to have misled everyone. So if you’re really believe you’re an anti-crackpot, I’m afraid you may need to buy a new mirror.
The true crackpots may be those who believe in string theory, supersymmetry and higher dimensions. Time will tell who the true crackpots really are.