At Fermilab the Tevatron is producing record amounts of luminosity, see here for a story about a celebration of this. Things also appear to be going well at the LHC, as the cooldown remains on schedule, and only a tolerable number (12) of PIMs needed to be replaced in the sector recently warmed back up. See here and here for some discussion of current planning for the next year. The machine should be cool and ready for beam commissioning in late June, and if all goes well, by September an initial physics run with 5 TeV beams at relatively low luminosity may begin. At these luminosities and energies, the stored energy in the LHC beam will be no greater than at the Tevatron (although the important number for physics, the per-particle collision energy, will be 5 times higher). The plan is to run until December, with a heavy-ion run at the end, then shutdown until April 2009. During the shutdown the magnets will be trained, allowing beams at the full energy of 7 TeV during the 2009 run.
Particle theory, especially string theory, is not doing as well. Data recently compiled about top-cited particle physics papers from 2007 shows only one [note added: should specify string theory here, at 27 and 31 are phenomenology papers from 2002 and 2000] theory paper from this century making the list of 51 most heavily cited papers, and that was the KKLT paper which is referenced by all “landscape” and “multiverse” studies. The sad state of string theory has even made it deep into the popular consciousness. Last week’s episode of “The Big Bang” featured a brilliant young prodigy explaining to the particle theorist character that his work on string theory was a “dead-end”, due to the landscape problem. Even economists are dissing the subject:
Modern financial theory as applied ranks with string theory in physics as one of the greatest intellectual frauds of our time. Whereas the vacuous pretensions of string theory have finally been exposed (we now know that the theory never generated a single falsifiable prediction), those of “financial engineering” are just beginning to be exposed both in the press and in lawsuits alike.
At Santa Barbara, Jennifer Ouellette reports on a workshop about “how to come off better during TV appearances”:
Joe Polchinski (inventor of D branes in string theory, and one of the few permanent members at KITP) also agreed to be mock-interviewed, revealing a sly sense of humor in the process. For instance, asked if there was any controversy about string theory, he deadpanned, “Oh no. Everybody agrees that string theory is correct.” It cracked up the room.
This workshop unfortunately didn’t seem to include the advice to just say no when asked by TV producers to participate in a short stupid comedy skit making fun of science and scientists. See here, here and here, for reports on Wednesday’s “Root of All Evil” show from Comedy Central, which featured a mercifully short segment making fun of scientists as incomprehensible geeks. Participating in things like this does about as much to help the image of science and scientists as appearing on a Spike TV segment about the use of physics to determine whether women can crush beer cans with their breasts.
Given that things are going very well with the LHC, and badly with string theory, string theorists are doing the logical thing: advertising their activities with graphics of strings superimposed on a picture of the LHC. See here and here.
Update: Minutes from the LHC Installation and Commissioning Committee April 11 meeting are here. They include the exchange:
L.Evans asked if the cryogenics teams are still on track for having the whole machine at operating temperature in mid-June. S.Claudet replied that taking the figure of 6 weeks from room temperature to 2K, and allowing 2 weeks of cryo tuning, sector 45 would be ready for hardware commissioning in the first half of July.
This indicates that beam commissioning is likely to begin in July, not June.
Also discussed was what to do about possible stray plastic parts in the beam tube:
Any pieces of plastic would be vaporised by the beam so we should not delay start-up to search for these.
Update: Commentary on this posting from Lubos here, including
I am amazed by the people who deliberately keep on opening the pile of manure called Not Even Wrong – it must be due to a really nasty deviation of theirs that dwarves pedophilia.
Peter,
Thanks for an interesting post today! I’m trying to figure out whether there are any definitive tests one can do to either validate or falsify string theory, and the overwhelming large parameter space the landscape provides seems to make this impossible.
I’ve written a little bit about it on my website here and here, but haven’t gotten any responses that explain whether string theory is, even in principle, testable at this point. What are your thoughts on it?
Best,
Ethan
Dear Peter,
I understand that luminosity is related to the number of particle events, a certain large number of which is required for the statistical probability of interesting rare events like the production of Higgs and/or SUSY-partners.
I understand for a given collision energy, a non-detection of an increased luminosity beam rules out the existence of Higgs and/or SUSY-partners at that energy (i.e Higgs does not have a mass below 130GEV with 2-sigma 95% before the luminosity upgrade, increasing to 3-sigma 99.7% with the luminosity upgrade)
I understand that Tevatron has had a “300x” increase in luminosity with a 100x increase in data, but how does this affect string theory? Neither string theory nor SM is committed to a specific value for the Higgs and/or SUSY partner masses, although it is obvious the increased luminosity constrains it. How does an increase in luminosity for TEV spell things going badly for string theory (unless you feel that TEV’s non-observation contrains what LHC might see)?
If particle experiment does well particle theory does well. The entirely correct model of TeV-scale physics may already be written down, published, on the arxiv – and attracting five citations a year.
Experiment alone will separate the wheat from the chaff.
The logic of counting citations to measure success says that particle theory is only doing well when there is a bandwagon that is acting as a paper factory. If (God help us) there were three hundred papers on unparticles this year would that really make 2008 a great year for particle theory? There is lots of interesting work around, but it is no bad thing if there is not so much ambulance-chasing.
Seems like someone is a bit jealous he wasn’t asked to be on “Root of all Evil” instead………
I feel I must point out that just because string theory is in a parlous state, doesn’t mean the rest of particle theory is. In particular, phenomenology is in a great state. There is more work in this area than there are people to do it, and career prospects are bright for young researchers entering the field.
Ethan,
String theory is simply not testable, by any conventional understanding of what it means to have a scientifically testable theory. I’ve spent much time here going over the arguments about this, I suppose I should spend some more and get them put together in some place I could easily point to. A FAQ, if you will…
dan,
The fact that the Tevatron and LHC are doing well has no correlation with the fact that string theory is doing badly. String theory has zero to say about what either machine will see.
piscator,
I just disagree with your statement that “there is lots of interesting work around”, but for some mysterious reason, almost everyone is ignoring it. If you have some data that backs up this point of view, I’d be interested to hear about it.
Jacob,
I suppose there’s a long list of things in life that other people but not me are invited to do and I’m jealous of this. Appearing on “The Root of All Evil” isn’t one of them…
we now know that the theory never generated a single falsifiable prediction
Maybe OT, but I am fascinated by the way this is phrased. “We now know”? It is as if this was only discovered in retrospect. “In 2006 a theorem was published which proved that no one had published a paper between 1986 and 2006 containing a distinct predictive model of M theory…”
At this moment, the motto of String Theorists seems to be: “If the mountain won’t come to Muhammad, Muhammad must go to the mountain”.
Dear Peter
“dan,
The fact that the Tevatron and LHC are doing well has no correlation with the fact that string theory is doing badly. String theory has zero to say about what either machine will see.”
String theory may have “zero” to say but what about SUSY-quantum field theory? Since string theory would probably go into decline if LHC-TEV does not see SUSY, and continue to flourish if it does see SUSY,
If SUSY does stabilize the EW scale, and some form of SUSY-field theory is used as a basis of some sort of prediction based on this, what does the current non-observation of a light higgs and other SUSY-partners at TEV’s increased luminosity imply with the likelihood LHC will see SUSY when the TEV currently has not, with its much increased luminosity.
Hi Peter,
I don’t think that’s even close to accurate. In fact, I think it shows a severe misunderstanding of popular culture, social interaction, and human nature in general.
It’s pretty basic…
An incomprehensibly opaque field populated with unaccessible inhuman humorless people who don’t act “normally” like the rest of us……that’s scary and scary things are burned at the stake.
Those smart guys who talk all that incomprehensible smart stuff, but they’re pretty funny and just regular people like the rest of us….If tv says they’re important, then I guess it’s ok to support them.
To see that this is true, just look at every government that has ever existed in the history of the universe. There is an entire political appatatus as a buffer between serious policy and the lay public….think of that skit as the incipient physics political arm.
Bad publicity is something like: Those smart guys think we’re stupid, and they’re trying to trick us.
Peter wrote
“….I suppose I should spend some more and get them put together in some place I could easily point to. A FAQ, if you will…”
A FAQ would be an excellent idea.
dan,
As the Tevatron gets more data, they presumably can push up a bit the bounds on SUSY, and there is a range of possible SUSY parameters that the Tevatron can’t exclude, and that the LHC could observe. But string theory has nothing to say about the values of these parameters, even about whether anything will show up in the LHC range.
I’m starting my phd on quantum gravity and already got sick about the existent situation. I’m tired of watching consecutive attacks against string theory (ST). ST did this, ST can’t do that, ST is the atomic bomb.
All we have in quantum gravity is 5-6 theories that did simply nothing for physics. No predictions, no experiments, nothing at all. Still, everyone still fights for the best theory to survive the game. “MY theory has unification!” yeah, but “MY theory is background indipendent, yours is not!” etc etc etc.
oh dear lord, why quantum gravity is so appealing to me instead of condensed matter physics, or photonics?
why?
Dan: “I understand that Tevatron has had a “300x” increase in luminosity with a 100x increase in data,”
Sorry for nit-picking, but it takes so little additional effort to be accurate… It bothers me when numbers fly loosely in a scientific argument.
The Tevatron had a x15 increase in the record instantaneous luminosity in Run II over Run I. The integrated luminosity in Run II is now 30x larger than in Run I, not x300. And that means a similar factor in the increased statistics for rare processes with high trigger and collection efficiency, say for instance top quark pairs; save a small (30%) additional increase due to the larger energy of the beams in Run II vs Run I (980 vs 900 GeV per beam).
Instead, the total bounty of data has not increased by x30 WRT run I, but just by about x10. That number is almost meaningless, however, since it is only connected to the data aquisition capabilities of the system, and has nothing to do with the size of “discovery” datasets (which have increased by about x30x1.3=x40, as I said above).
Cheers,
T.
Interesting that there is a workshop on how to look better on TV!
As a government scientist (U.S. Nuclear Regulatory Commission nuke inspector), I’ve had to go through about 6 week-long training courses over the past 17 years, in which we were videotaped and our taped performances critiqued, etc. One such course dealt specifically with how to handle interviews by the media, which was taught by ex-media personnel.
Now I’m just waiting to get on TV!!! (but not as a result of a nuke accident of course!!)
> All we have in quantum gravity is 5-6 theories
> that did simply nothing for physics.
This is a bit of a murky area. Because science is not JUST about predictions, but also about understanding. Epicycles could make excellent predictions for planetray motion, but understanding came only with Newton.
String theory does give you its share of Aha! moments. I will just mention one that I haven’t seen mentioned much to the general public: Mathur’s fuzzball proposal for black holes. It is very hard to believe that we do not understand the essential mechanism of black holes after you read, say, hep-th/0502050. Of course it is possible that “real” black holes don’t fit with the plan, etc. etc., but thats mostly because everything is possible.
The basic point is that string theory seems like a good theory of some quantum gravity – but not manifestly ours. I think this is reason enough to work on it.
> No predictions, no experiments, nothing at all.
Yes, expriments are hard to come by in this day and age. But should we shut down speculative theory because of that? Heck, thats all we got! The other option seems like throwing the baby out with the bathwater to me.
Given that things are going very well with the LHC, and badly with string theory, string theorists are doing the logical thing: advertising their activities with graphics of strings superimposed on a picture of the LHC. See here and here.
At least the first graphic I am sure I’ve seen before, I think on a workshop called ‘Strings at CERN’ in 2004 or so.
re chethan krishnan:
i think the gist of the opposing argument is that the
bath water is cold. take the baby out , dump the water
and get some more hot water.
> i think the gist of the opposing argument is that
> the bath water is cold. take the baby out , dump
> the water and get some more hot water.
I am glad you got the maximum mileage out of that bit. 🙂
If there is a new theory that is more promising than string theory, by all means I am for it. I am just not happy with the sitting around and waiting for it part. In the meantime, exploring string theory seems like the most useful thing to do to get some insights into quantum gravity. The fact that it might even be right, adds to the attraction.
Also, the inherent difficulty of testing quantum gravity at low energies makes me suspect that speculating will be inevitable to get a glimpse of the truth. Which is why I find arguments against speculative theories not so compelling. My claim is that even though the issue is often portrayed as string theory vs. something else, it really reduces to theorizing vs. no theorizing.
Over and out.
>chethan krishnan Says:
>If there is a new theory that is more promising than
>string theory, by all My claim is that even though the
>issue is often portrayed as string theory vs. something else, it really > reduces to theorizing vs. no theorizing.
Chethan,
I think you are right, if there are only certain problems you want
to theorize about. But there are other things besides gravity
and unification to theorize about. Your view is the mainstream
one in theoretical high-energy physics, of course.
Personally, I don’t think quantum gravity is an important science question, though it is certainly a fun and interesting question. I would write a paper about it (and have once or twice), if I had an idea concerning it I liked; but it just doesn’t interest me as much as other problems. The Planck mass just can’t be studied with experiments. Quantum gravity may be fun, but it also seems like a distraction from serious physics. People who hold this view aren’t loved by their colleagues (I don’t think we are disliked either, just ignored), but there it is…
‘… the inherent difficulty of testing quantum gravity at low energies makes me suspect that speculating will be inevitable to get a glimpse of the truth. …’
You’re judging alternative theories by the criteria of string theory. In string theory, quantum gravity effects are important only at unobservably high energy scales.
Take a look at all the loose ends in classical gravity at present (dark energy, dark matter, etc.) which quantum gravity should say something about at low energy where general relativity is a classical approximation to quantum gravity.
An alternative to string theory may predict the amount of dark energy, i.e. the lambda term in the classical general relativity solution which will emerge as an approximation for low energy.
That would be a checkable prediction. String theory can’t do it because of the landscape problem, but some alternative quantum gravity theory might be able to predict lambda. Just because string theory is a failure, doesn’t mean to say that all other ideas will be a failure, too. They just haven’t had the concentrated attention and effort devoted to them yet, that string theory has received for ages.
chetnan,
The only people I see suggesting “sitting around and waiting” as a research strategy these days are string theorists, who are unwilling to give up on a failed theory, and instead advocate waiting for LHC results that will “narrow the parameter space” of possible string theory vacua to be investigated, or produce some unexpected result which will fuel the next theory bandwagon for them to hop on to.
The only way a new, more promising theory will come about will be from people working on trying new things, not from sticking to tired, familiar ideas that they are comfortable with even though they don’t work (for by now well-understood reasons). If you don’t want to try to find something new, why bother spending your life working in this area? The world is full of all sorts of interesting things to do and to think about, devoting yourself to a failed idea because it pays the rent isn’t much of a way to spend one’s life.
But there are other things besides gravity
and unification to theorize about. Your view is the mainstream
one in theoretical high-energy physics, of course.
Judging by where the money’s going, I don’t think that’s an accurate assessment anymore.
To anon: If you happen to have a theory of quantum gravity, or really anything at all, that has something useful to say about the cosmological constant, I think you’d find that people will start studying it very quickly.
“who are unwilling to give up on a failed theory, and instead advocate waiting for LHC results that will “narrow the parameter space””
You seem to think that unless a theory can uniquely predict everything that will be seen at LHC from first principles, then the theory must be no good. I’d like to ask, when has such a thing ever happened? The Standard Model was produced with the guidance of experimental results, not deduced beforehand. You’re like some guy around 1960 going around complaining about how Yang-Mills theory is a total failure and waste of time because it can’t predict anything.
Really, you’re just the equivalent of a Rush Limbaugh for science. All one has to do is replace ‘string theory’ with ‘liberalism’ in your diatribes and it’s a one-to-one mapping. Indeed, you were probably the main source for articles such as
http://www.conservapedia.com/String_theory
People who read such articles and take them seriously are your intellectual brothers.
“You seem to think that unless a theory can uniquely predict everything that will be seen at LHC from first principles, then the theory must be no good.”
Monkey,
For the 10,000th time, the problem with string theory is not that it doesn’t “uniquely predict everything” that the LHC will see, but that it predicts absolutely nothing at all about this (or anything else for that matter…).
Thanks for the link to “Conservapedia” where the entry for string theory states “As of today, string theory has been a total failure.” That’s not a web-site I would normally ever consult, interesting to see that the “string theory has failed” meme is even showing up there. Someone should tell Lubos.
Seeing all the bad press string theory is getting some days makes me feel sorry for string theorists. I tend to get over this pretty quickly though when I see how they are reacting to it, e.g. by making bogus claims about testability and the LHC.
Just as a random note, why is it that falsificationism and positivism seem to be conflated so often? (Conservapedia, admittedly not a source known for its accuracy, is just the latest I’ve seen.) As I recall, Popper came up with falsificationism as an explicit reaction against positivism which was more concerned with making meaningful statements (a sort of verificationism).
“the problem with string theory is not that it doesn’t “uniquely predict everything” that the LHC will see, but that it predicts absolutely nothing at all about this (or anything else for that matter…).”
Exactly the same thing could have been said about Yang-Mills theory in the fifties and sixties. Yet, the Standard Model turned out to be a Yang-Mills theory. In reality, string theory is presently in the same place today as the quantum theory was from the period 1905-1925, before the formulation of quantum mechanics.
“string theory is presently in the same place today as the quantum theory was from the period 1905-1925”
Monkey,
If you want to get some idea of the broad range of convincing experimental tests passed by the old quantum theory, you might want to look up the Nobel citations for Planck (1918), Einstein (1921) and Bohr (1922). These were not people who spent their time making up absurd excuses for not having a testable theory, and the Nobel committee didn’t give them Nobel prizes based on such excuses.
Peter,
Please explain to me how the photoelectric effect and the emission spectra from the hydrogen atom were tests of the quantum theory (using the criteria you apply to string theory)? Both of these phenomena were well-known before either Einstein’s or Bohr’s models, so I don’t think you can claim that the quantum theory of this time made any testable predictions. Indeed, the Bohr model is in fact not correct. Rather, the quantum theory itself was pieced together bit by bit using these experimental data as guidance.
As a counter example, I can construct string models with three generations of chiral fermions which transform as representations of the SM gauge group, just as Bohr used the quantum theory to construct models of the hydrogen atom. In neither case, do we make any new predictions. However, the models themselves may lead us to a deeper understanding.
Monkey,
It’s just simply not true that all Bohr did was “construct models of the hydrogen atom” that predicted nothing.
Peter, is it really true that string theory failed to make any predictions, did they predict a cosmological constant would have to be negative in the 1990s?
10, 000 monkeys, the Bohr model of the hydrogen atom was able to explain things that nobody else was able to explain – the emission lines of hydrogen. The theories available at the time predicted the electron should crash into the proton… whereas the standard model has a solid grip on particle results. Does ST have such a result? Einstein got a value for h in his photoelectric experiments that matched the h that popped out of Planck’s equations for the blackbody spectrum. That’s pretty good.
They worked off not understood anomolies such as atomic spectra. We’ve now had equally not-understood anomolies such as dark matter for thirty years, and dark energy for ten. We have a curiously flat and uniform universe. There’s a lot that no one understands, as much as there was in 1905.
Hey Peter, have you seen this article, string theorists weigh in on what they think the LHC will see, and how it affects string theory
http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/03/25/scibigbang125.xml
http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/03/25/scicomments125.xml
For copyright reasons I won’t reproduce what they say here except this:
MARTIN VELTMAN “As for string theory, it’s all mumbo jumbo, with no connection with experiment.’ I wonder if he came to this conclusion on his own or as a result of reading your work and the controversy it has inspired
NIMA ARKANI-HAMED “My hunch is that there’s a better than evens chance that supersymmetry will show up at the LHC”
EVA SILVERSTEIN “I’d be extremely puzzled if they don’t find the Higgs, but wouldn’t be devastated if they didn’t come up with evidence for supersymmetry.
‘Some of my intuition comes from string theory, an appealing candidate for a theory of all the forces of nature. According to many – perhaps most – versions of string theory, supersymmetry does not hold good at the energies probed by the LHC, so its discovery might require further explanation from this point of view.”
PW, Eva’s statement comes as news to me, is there any reason why Eva (and some of the other string theorists interviewed) are backpeddling from seeing SUSY at LHC energies, given the ‘hierarchy” argument for SUSY in the EW-scale? Eva is now claiming that string theory SUSY probably won’t show up at LHC energies, but that if SUSy does show up, string theory would need further explanation.
If LHC does not see SUSY, could SUSY still be (experimentally speaking) the explanation for hierarchy argument (if the SUSY-breaking scale is above what LHC can produce/detect) which is what Eva seems to be saying.
David,
There never were serious claims that string theory “predicts” a non-positive CC, although as late as 2001 Witten was writing that he knew of no “clearcut way” of getting a positive CC out of string theory.
If you look at the Einstein Nobel citation you’ll see that it explicitly refers to detailed tests of the photo-electric effect performed after Einstein’s proposal that tested and confirmed his predictions.
dan,
Thanks for pointing those out, I hadn’t seen those quotes. The Silverstein quote that
“According to many – perhaps most – versions of string theory, supersymmetry does not hold good at the energies probed by the LHC”
is a bit striking, given that many string theorists in the past have claimed low-energy supersymmetry as a “prediction” of string theory, and that if it does show up, they certainly will claim it as evidence for string theory.
I think what she is referring to is the idea that one can show that there are more string vacua with SUSY breaking at high energy than at low. If SUSY doesn’t show up at the LHC, Arkani-Hamed and others will claim this as evidence for the landscape, on the grounds that the only possible explanation for the hierarchy is an anthropic landscape.
Veltman has always been a string theory skeptic, he didn’t get that from me…
David,
The Bohr atom didn’t explain anything, it merely fit the data that was available namely, the Balmer series. As for the stability of the atom, Bohr only gave an ad hoc rule for this, which was to say by decree that orbits satisfying the angular momentum quantization rule (which was again ad hoc) were stable. This is not an explanation, merely a phenomenological model. Even though the Bohr model was almost completely wrong in almost every respect, it was still useful, mostly because it led to the deBroglie wave/particle duality. This of course, then led to the Schrodinger equation.
Regarding the Silverstein statements regarding not being upset about the prospect of not seeing supersymmetry at LHC, Peter is correct. I’ve heard this from Kachru himself, who made the accompanying statment that ‘Natural is whatever nature does’, to justify why the anthropic arguments to solve the hierarchy problem are no more unnatural than supersymmetry.
Peter,
I thought Eva’s guess was based on the fact that the light higgs, higgs, and SUSY has not been seen at TEV, which constrains and decreases the likelihood low energy hierarchy-solving SUSY will be observed at LHC, or 50-50 as NIMA ARKANI-HAMED quantifies it.
Eva’s argument seems specious to me since even if most vacua imply a high-scale susy-breaking than is unattainable at LHC, I would use the anthropic principle to argue that we happen to live in a universe where the SUSY-breaking scale is close to the EW breaking scale (within LHC energies) so as to solve the hierarchy problem. In a multiverse, we would not exist in a universe with a high energy SUSy breaking, as it would allow the Higgs boson through radiative quantum contributions to pull up to the GUT or planck scale.
If LHC doesn’t see SUSY, then evidently SUSY isn’t the correct explanation for the hierarchy problem, is there any experimental or observational reason to think SUSY is a true but broken symmetry of nature besides the running coupling constants?
dan,
if you ever heard veltman talk on anything, you would have instantly recognized that he is a critic of everything except feynman diagrams. i am not sure he even takes local QFT as well established fact.
monkey,
i encourage you to stop embarrassing yourself and do as peter suggested: read up the nobel citation for bohr.
Monkey,
Your reasoning is completely confused, read your own comments. You’ve eventually come to claim the thing to do is making ‘phenomenological models’ that are ‘useful’ because they can lead to further insight. I couldn’t agree more! Just that you started up claiming essentially the opposite, namely that theories do not need to give rise to models that make predictions that test the theory. I think you have somewhat of a confusion about models and theories (recommended reading). Best,
B.
Dear Bee,
I’m not sure where I claimed that theories do not need to give rise to models that make predictions that test a theory. I certainly hold no such opinion. However, you must first get to the point where your theory is understood well enough to do this, and generally you need to be able to construct specific models. In the previous example I gave regarding Yang-Mills, there is absolutely no chance that the Standard Model can be derived directly from YM. Indeed, the SM is but one of a vast landscape of possible Yang-Mills theories. To discover which one describes our universe, we construct models that describe the known data and try to fill in the gaps. Once the model is sufficiently developed, then testable predictions can be made. This is how science works.
The Bohr model made several crucial predictions. It predicted the existence of new lines in the hydrogen spectrum, although this probably could have been done using numerology alone. Much more important, it predicted that the quantized nature of the spectrum was related both to the quantization of light as photons and the quantization of the energy levels of atoms. The former form of quantization was still gaining acceptance, although its utility in explaining physical phenomena was already demonstrated. That the atomic levels of hydrogen (and by extension, all atoms) were quantized was completely new. This property of the Bohr model made many strong predictions, such as the outcome of the Frank-Hertz experiment.
Brett,
The Bohr model did not predict any new lines in the hydrogen atom. At best, it merely gives the Rydberg formula. As far as the quantization of energy levels is concerned, this is a postulate of the model, not a prediction. For all practical purposes, it was a lucky guess. Don’t get me wrong, I am not puttying Bohr down. He was a first class phenomenologist and philosphopher.
its amazing how many geniuses come up with lucky guesses.
“For all practical purposes, it was a lucky guess.”
I see, the only difference between string theorists and Planck, Einstein, Bohr is that they haven’t been as lucky…
The argument that Monkey is making I think is based upon a somewhat different argument that David Gross is fond of, that, at the conceptual level, one should think of the present state of string theory as analogous to that of the old quantum theory, a patchwork of ideas that indicates the existence of a still unknown underlying well-defined theory.
I always thought it was a bad idea for Gross to promote this analogy, since there were obvious huge problems with it, especially problematic being that the old quantum theory had a huge amount of experimental backing, while string theory has none. Monkey’s comments indicate that my concern was justified.
Are you guys that are so fond of the ‘genius’ Bohr aware that he advocated giving up the principle of energy conservation?
At any rate, I put Bohr’s model on the same level as the deBroglie wave hypothesis. Both ideas were brilliant and lead us to the correct theory, quantum mechanics, but the ideas in themselves are not completely correct. This is the essence of bottom-up phenomenology, as opposed to the top-down approach.
>The only way a new, more promising theory will come about
> will be from people working on trying new things, not from
> sticking to tired, familiar ideas that they are comfortable with
Not sure there is a recipe for scientific revolutions. One thing I am fairly certain of is that pushing the current ideas to their limits is probably going to be essential to see beyond them. In the case of quantum gravity, string theory is certainly a way to gain such insight, whatever its ultimate use.
> even though they don’t work (for by now well-understood
> reasons).
:).. Right.
> If you don’t want to try to find something new, why bother
> spending your life working in this area?
Not wanting to try something new? Try what? The only way to come up with something new that is non-crackpot is to understand the existing ideas well enough to know their holes.
Besides, we are all clutching for straws here! It is easy to sit there, play critic, condescend, etc.
> The world is full of all
> sorts of interesting things to do and to think about, devoting
> yourself to a failed idea because it pays the rent isn’t much of a
> way to spend one’s life.
Thanks for the career advice. I guess! 🙂
Its amazing the bitter resentment here, even when we are just trying to have a conversation.
chethan krishnan Says: “…Besides, we are all clutching for strings here!…”
You had a typo. I’ve fixed it for you.
chethan,
No, there’s no “bitter resentment” here. I’m quite happy with my life and things I’m working on. Life is good. I happen to think that the decision by much of the particle theory community to keep pursuing string-theory based unification despite the increasingly obvious failure of the idea is a mistake, and this is worth pointing out. The argument that “let’s keep doing this, maybe something will turn up” has been made for many years now, and has just led to the field working itself farther and farther down a blind alley. Sooner or later this will have to be acknowledged. Sooner would be better.
Monkey,
I understand your point that Bohr model did not predict anything new, it has just explained something already known. Ok, let me agree ( even if it may not be true). Let us forget about predictions altogether.
Just explain, no need to predict. I am placing a lower acceptance criterion than Peter usually put on string theory. Just give me a model, which has standard model gauge group, three generations, all moduli stabilized and with reasonable cosmological constant and particle mass. Do not even bother about whether it is unique and stuffs like that. Just give me one. Do not say that there are so many string models in the landscape one will certainly match with Standard Model. Give me an example. Just one….
Please…
PW,
playing DA here, “especially problematic being that the old quantum theory had a huge amount of experimental backing, while string theory has none.”
the LHC isn’t online yet. If, hypothetically speaking, SUSY does show up at LHC, this would be a reason theorists to claim string theory has experimental backing.
that offhand remark about no need for searching after hapless things that may stray into the beam path (for they shall be vaporised in instant)…..”At last, we have ways to make you pay attention. New physics is not here to be posessed by the faint-hearted theorists!”
nbutsomebody,
There are such models in the literature which closely resemble the MSSM, and where all moduli may be stabilized. However, at this point I don’t want to say more for fear of being accused of self-promotion.