Today’s San Francisco Chronicle contains an article about string theory entitled “Theory of Everything” Tying Researchers Up In Knots. It’s by science writer Keay Davidson, and is about the most skeptical article on string theory I’ve seen in the mainstream press. The lead sentence is:
“The most celebrated theory in modern physics faces increasing attacks from skeptics who fear it has lured a generation of researchers down an intellectual dead end.”
Davidson contrasts Michio Kaku’s very pro-string theory point of view in his new book Parallel Worlds, with the much more skeptical views of Lawrence Krauss, who evidently has a book entitled “Hiding in the Mirror: The Mysterious Allure of Extra Dimensions” coming out in September. He also got comments about the current state of string theory from quite a few different people, including yours truly. The article contains a link to this weblog.
Some of the string theory critics quoted are just inherently opposed to any new mathematical approach to fundamental physics, something I have no sympathy with. One of these is Stanford’s Robert Laughlin, who makes the point that string theorists are trying to camouflage the theory’s increasingly obvious flaws by comparing the theory to “a 50-year-old woman wearing way too much lipstick.” Because of Laughlin’s extreme anti-mathematical theory views on the one side and those of his colleagues like Lenny Susskind on the other, “The physics department at Stanford effectively fissioned over this issue” says Laughlin. He goes on to say “I think string theory is textbook ‘post-modernism’ (and) fueled by irresponsible expenditures of money.” For the record, I’m no more of a fan of Laughlin’s views about particle theory than I am of Susskind’s.
Some of the quotes from defenders of string theory are a bit strange, with none of them addressing the fundamental problem the theory is facing these days as it becomes obvious that it can’t predict anything. John Schwarz is quoted as saying “string theory is the only approach that has the potential for explaining dark energy” which is kind of peculiar since it is well-known that superstring theory naturally leads one to expect a value for this energy density that is off by 120 orders of magnitude. The only way around this seems to be the “landscape” argument, in which you essentially give up any hope of ever predicting anything. The other defenders of string theory quoted in the article mainly try and claim that twenty years of work on the theory is still nowhere near enough, that it is way too early to be able to evaluate it yet. They don’t give any indication of how much longer we should wait for such an evaluation, but if twenty years isn’t long enough, it sounds like they hope this won’t occur while they’re still alive.
Update: For a very different take on this, see Lubos Motl’s posting.
To ksh95: You don’t actually seem to have read anything I’ve said beyond the first sentence.
Try, for example “On the other hand, I firmly believe that we have to practice science as if the anthropic principle were false, but that’s another story.”
ksh95, very funny, but..
The real problem is, I don’t think it’s possible to argue with these folks. They just don’t care. The watchword is, “Be the Wibble.”
-drl
I forgot to mention, as presently formulated the anthropic principal isn’t even a useful calculation tool. If, for instance, an anthropic principal based string theory could reduce the 20some parameters of the standard model to 5 parameters, then I would be at least willing to acknowledge the anthropic principal as a valuable calculation tool.
Aaron said
“…And, I agree with you that the anthropic principle is nonpredictive. My only point is that it really could be the right answer…”
Your point of view really makes no sense to me.
The anthropic principle can never be the right answer any more than it can be the wrong answer.
As far as I’m concerned the anthropic is equilivant to:
The reason Peter really started this blog, and the reason I replied to your post is because there is an acausal point in spacetime that effects all other points. That point is inside
Wibble the three-toed chicken’s head at time infinity + 7. Wibble determines the past by thinking in the future….Actually, this argument is slightly better than the anthropic principal since it may be possible to rule out
acausal influences on present events.
If, as you say, the anthropic principal is really the true state of the universe, then the answer produced by science must be that the true nature of the universe in unknowable. At this point physics reaches its end. Some go on to believe in the anthropic principal, others believe in Creation, while I believe in Wibble the three-toed chicken.
Susskind may cloud his ideas in prose about a cloud covered earth and such things, but what he really advocates is reformulating science such that it looks something like “…If we assume A (which can never be proven or disproven) then the rest of the universe follows…”
I say why make it hard on ourselves by letting A=multiverse. If we would have let A=Wibble the three-toed chicken we could all have avoided a lot of years of schooling.
Since Peter deleted my previous post, I reproduce it again but extended and without the supposed “speculations on own work”.
During some time I wrote several comments regarding the impressive failure of stringy research. It is unnecessary a costly experiment for showing this.
The basic idea of stringy research is as follows: to take the hypothesis A and make one article, next neglect the hypothesis and make another article contradicting the first one. Even with this infinite malleability, string theory has shown to be a failure. Perhaps failure is a harsh strong word for sensible people, but I would remark that physics is just one of hard sciences, and “hard” signifies hard.
Dear “”, do you know that some people is working in more than 11D whereas others are claiming for a 4D string approach?
The history of dimensionality (I do not include Kaluza-Klein) is
4D -> 26D -> 10D -> 11D -> 12D? 13D? 4D?…
History shows us that if you write two columns and at one (left) write the past claims of stringys and the other (right) our current knowledge, you find a surprising feature.
the entire left column was completely wrong!
Of course, string theorists will say you that the topic is open. This is not an excuse! Decades ago, stringys claimed in public that the theory was the Last Formulation. What arrogance! Some of use already knew that the elementary stringy approach could not be applied to simple piece of hot water. Now, they are using the TFD approach for a generalization of the “old” brane theory based in the outdated Hilbert-Fock space mathematics and the standard vacuum. However, even using TFD, brane theory is still not sophisticated enough.
Therefore is not necessary experiment for understanding that string theorists are in the wrong way. I am not saying that are clever guys or no, just saying that are in the wrong way as Eisntein when ignored the rest of science and focuses on its own (wrong) idea about the world. Therefore, the recent words of Susskind are not surprising for some of us that studied string theory and pointed to its obvious flaws.
“Many physicists hoped that string theory would be the mathematical ‘silver bullet’ that would uniquely explain our world. But the more we learn about cosmology and the more we learn about string theory, the less likely this seems.”
Lisa Randall (from Harvard) says:
“Originally, string thoeirsts hoped string theory would dictate these parameters. But this is looking increasingly unlikely.”
On a this year comment, Witten states:
“One of the few things we do know is that, with string theory, theoretical physicists have stumbled upon a theory that looks like it might be the unified field theory.”
Humm… He now abandons his earlier grandiloquent evaluation of the theory and carefully uses the combination look like it might. Interesting!
More comments on this article can be found here.
Witten is denounced by his mentor Penrose, ‘Road to Reality’ (UK ed., 2004). On page 896, Penrose analyses those who use string ‘theory’ as an obfuscation of gravity’s cause:
‘In the words of Edward Witten [E. Witten, ‘Reflections on the Fate of Spacetime’, Phys. Today, April 1996]:
‘ “String theory has the remarkable property of predicting gravity,”
‘and Witten has further commented:
‘ “the fact that gravity is a consequence of string theory is one of the greatest theoretical insights ever.”
‘It should be emphasised, however, that in addition to the dimensionality issue, the string theory approach is (so far, in almost all respects) restricted to being merely a perturbation theory …’
More at http://members.lycos.co.uk/nigelbryancook/Penrose.htm
Lubos,
Thank you for explaining your position. You are right: the article was weak and should have been stronger.
I think you are however, exactly missing the point from my perspective. I hope you find this post informative; no one wants you to become yet another string theorist who never matured into a particle theorist.
Richard Feynman (a non-expert in string theory who might have been interviewed if he were alive) left us the following admonition:
“Details that could throw doubt on your interpretation must be given, if you know them. You must do the best you can–if you know anything at all wrong, or possibly wrong–to explain it. If you make a theory, for example, and advertise it, or put it out, then you must also put down all the facts that disagree with it, as well as those that agree with it. There is also a more subtle problem. When you have put a lot of ideas together to make an elaborate theory, you want to make sure, when explaining what it fits, that those things it fits are not just the things that gave you the idea for the theory; but that the finished theory makes something else come out right, in addition.”
Can you hear the music, or is your mind already thinking about retorts?
Those of us non-string theorists have been waiting for the informed self-critique of string theory to come FROM the string community. Some of us have been waiting for 20 years.
Because String theory is nearly opaque to an outsider, we are actually dependent on string theorists to be their own worst critics.
By all means Lubos, save us from the Woits, the Andersons, the Friedans, the Feynmans, the Glashows. Now is your moment. Tell us EVERYTHING you know to be seriously wrong with the theory, its practitioners and its history. When theories, mature, they become a bit more humble. Unfortunately, it appears from your posts that you do not yet enjoy that luxury.
Of course, maybe you just don’t know the history.
Do you know that people who used to work on 11D supergravity before strings were derided by early string theorists who thought it irrelevant? That for years 10 and 26 were proclaimed as the ONLY relevant dimensions? Are you aware that there were once a provably small finite number of string theories and that this fact was used relentlessly to sell string theories to a sceptical and largely disbelieving world? Are you aware that for years there were emphatic dismissive answers to the question of ‘why are strings the only extended objects with branes irrelevant’?
One could go on I suppose. Let me simply observe however that as string theory improves, it has been proving itself to be wrong in its earlier zeal and dogmatism for years. It just never stops to face its former incarnations.
Lubos, you are young and will be forgiven because of what I assume is your brilliance and contributions. But, like others before you, you will also run out of time if you don’t make contact with the world beyond string theory. We have been cheering for the String community for what is beginning to feel like an eternity. We hope like the Red Sox you will eventually get it together and win one for all of us.
Oh and one last thing. The theory community as a whole has built up a lot of good will over the years by achieving a great deal scientifically while teaching its non-experts critics rather than deriding them. Just make sure you put back scientifically far more than you withdraw.
That is quickly becoming a tall order.
“My objection to Aaron is that he seems willing to take seriously theoretical ideas that don’t make any predictions.”
These days, I’m mostly interested in the mathematics part of strings. And, I agree with you that the anthropic principle is nonpredictive. My only point is that it really could be the right answer.
Depressing, I know, but not impossible.
I saw the Kolb et. al paper last night, was thinking of writing something about it here, but have been too busy. Also, I’m not enough of a cosmologist to know how to evaluate what they are doing. I hope we’ll hear from Sean Carroll about this. (Sean, you reading this?).
If they’re right, and the CC really is zero, that would be quite something. It would certainly put a big dent in the “Landscape” nonsense.
Peter, check out http://www.arxiv.org/abs/hep-th/0503117 : Rocky Kolb and some others obviate the need for dark energy by explaining how standard inflationary cosmology gives you accelerated expansion. If there’s no cosmological constant, will string theorists give up on any of their nonsense?
Thanks, Peter, I’ve added a link, too. Today I have also huge traffic – because of the no-confidence vote – so it’s about a fair deal… 😉
Peter said:
“There’s nothing inherently wrong with the idea of fundamental constants varying with time and place.”
I disagree. There is something inheritantly wrong by assuming fundamental constants may vary. It’s inheritantly inconsistent with the principles of relativity, which says there is no special reference frame and no special place and time. All physics laws should look the same regardless where you make your observation and from what reference frame you make your observation.
Should findamental constants, like alpha, varies. Then we have to assume that all atoms and elementary particles around us would have to have the magic power of knowing where in space and time they sit, and collectively but independently decide on a specific alpha value, which is appropriate for their position and time, on which alpha value they thus exhibit their behaviors for us to see in the lab. Where would they acquire that “magic power” of knowing what is the “right” constant value? And how they would acquire that information? It’s simply incomprehensible that is the case.
Certainly it is possible that experiments could indeed reveal a changing alpha, then we would have to re-think our reasoning and exam where it got wrong. But so far any experiment attempting to reveal a changing alpha has been very sketching, very doubtful, none-repeatable, and unconfirmed.
Remember the big noise of “changing light speed” by the Weber group 5 years ago? I was skeptical to start with. Where is that noise today? Why there is no followups or independent verifications? None!
In today’s fiercely competitive academy environment there is full of dishonesty every where and one has got to be very skeptical in carefully evaluating any experimental results.
The so called CSL-1 cosmological string thing, is going to be the same Weber story 5 years from now. By this time there should be plenty of telescopes around the world take photo shots on this object. There is no independent confirmation so far! Isn’t it laughable that string theorists jumped up to their joy at the first moment seeing this insignificant peck of dust in the image as “amazing confirmation (of their theory)” which is actually just a straw.
Quantoken
Hi Lubos,
Sure, I’ll put a link to your posting. I had thought you would be too busy with the Summers affair to write about this….
Great that I convinced you, Peter. For the sake of hearing both sides, I propose that we exchange links to our reviews of the article.
All the best
Lubos
Hi Lubos and anonymous,
No, I’m not anonymous. I also think Lubos’s comment is perfectly relevant. I encourage anybody who is interested in the whole question of what is going on in string theory these days to read both what I write and what Lubos writes, then make up their mind themselves who has the better argument.
Dear “anonymous”,
it is not hard to determine that the author is not actually “anonymous” but it is Peter Woit.
All the best
Lubos
Dear Peter,
Could you please delete the last post — its completely irrelevant to the topic.
For all readers who come from San Francisco Chronicle, a trivial comment: Peter Woit is ignorant not only about string theory, but also about modern theoretical physics and particle physics in general.
If you prefer a treatment of the string theory and theoretical physics topics that is more sensible by a few orders of magnitude, read
Lubos Motl’s reference frane
L.M., Harvard
There’s nothing inherently wrong with the idea of fundamental constants varying with time and place. But if you want to turn this idea into physics, you have to come up with a specific theory that implements this, one that makes some sort of predictions you can then go out and check. My objection to Aaron is that he seems willing to take seriously theoretical ideas that don’t make any predictions. I’m not, especially when the whole motivation for doing this is to prop up a failed research program.
Peter: Correct me if I’m wrong — I’m not a physicist — but the idea of multiple universes, while counterintuitive, seems grounded in reality, not merely “concievable”. Relativity divides any unimaginably large, temporally bounded area into smaller universes (not with objectively defined borders, of course, but you get the idea); all you need in an unbelievably large area with fundamental constants shifting slowly over distance and voila, a huge number of slightly different universes.
(I’m not sure the terminology in that paragraph was right; hopefully the point came through.)
Judging from a post in the beginning of this thread, Prof. Nauenberg, who was on the faculty (perhaps visiting) when I was a graduate student, has come out as a string (or at least Landscape) skeptic.
I posted a long comment on Peter’s previous post (“Clifford Modules”) whose final section elaborates on the ideas sketched in my comment below (somewhat off-topic) on science and the Anthropic Principle. The preceding sections are more directly concerned with the topic of that post (but perhaps not enough).
JC – I should also mention that the prime mover behind the Weyl theory, strict locality (what Weyl called “pure infinitesimal geometry”), is the very same prime mover behind the various conservation laws that appear in particle physics, and lives on nearly identical mathematical territory.
-drl
JC – Weyl’s theory was almost exactly carried over into particle physics, only the gauge parameter was not the spacetime scale as such, rather, the phase of the wave function. I’d say this qualifies as “continuing essential relevance since 1918”. In contrast, KK theory was already an historical footnote by 1935, and should have remained so in light of Pauli’s analysis of its structure. It was clear to many of us that the string program was utterly doomed from the beginning, precisely because it relied essentially on retrieving a total failure from the dustbin of history. This has proven to be exactly right.
-drl
-drl
When was the last time there was an ambitious theory or experiment which tied up 20+ years of many physicists’ working lives, but still ended up in failure?
The only cases I can think of offhand were all those guys which worked on various unified field theories in the 1920’s and for some decades afterwards, which largely produced nothing. Other than perhaps Kaluza-Klein theory, one hardly hears about any of their old theories today.
Quantoken + Tony,
Please discuss this somewhere else. I’ll delete any further comments about this that are submitted.
Tony Smith:
Your calculation is pure numerology and has nothing to do with super string theory. It’s not even an impressive numerology at all, to get a rough match of 75:20:4.5. I have looked at various forms of numerologies and I am getting good at recognize them when I see one. Unfortunately some times it is hard to make a distinction between real hard science and true numerology.
Quantoken
Peter, you say:
“… there isn’t … any string theory argument for the CC other than the landscape because one (Ooguri, Vafa, Verlinde certainly don’t have one …) …”.
If you allow “string theory” to include theories in which the strings are physically interpreted as world-lines (long strings as real particle world-lines, short strings as virtual particle world-lines), then you can get a path to a unique “string theory”:
1 – 26-dimensions comes from usual string theory considerations;
2 – require Jordan algebra structure, which gives you the 26-dim traceless part of the exceptional Jordan algebra J3(O);
3 – require complex domain structures and Jordan symmetry, which give you the E6 Lie algebra with grading
8-dim g(-2) + 16-dim g(1-) + (28+2)-dim g(0) + 16-dim g(1-) + 8-dim g(-2)
4 – that graded structure, plus orbifolding, gives my physics model as described in my paper at CERN-CDS-EXT-2004-031 ( note that it is in LaTeX, so those who are picky about style should be happy ).
Once you are in contact with my model, you can then, using Segal’s conformal ideas, calculate the ratio Dark Energy : Dark Matter : Ordinary Matter getting a result that is close to the WMAP observations.
If you interpret Dark Energy as CC, then the above is an example of a uniquely defined (without landscape) string theory model that quantitatively describes the CC. As to the WMAP calculations in detail, they are given in pdf form in a paper at http://www.valdostamuseum.org/hamsmith/WMAPpaper.pdf Such a paper was rejected by arXiv in 2004 because I am blacklisted, and by the time I got around to thinking about putting that paper on CERN EXT, it had been terminated, so neither arXiv nor CERN EXT has archived my work on the WMAP ratios.
It is interesting that no string theorist has ever communicated to me either:
A – a specification of a fatal error in the above ( negative comments have not pointed to technical flaws, but only said that my work is complicated, that it involves orbifolding, or that it does not use the usual naive 1-1 supersymmetry of superstring theory, all of which are true);
or
B – said “thank you” for finding a specific string theory model that agrees qualitatively and quantitatively with gravity plus the Standard Model.
That indicates to me that not only are string theorists unable to do anything useful (re constructing physics models) with their stuff, but also that they don’t like it when that is done by an outsider.
Tony Smith http://www.valdostamuseum.org/hamsmith/
Aaron said:
“Do you agree or disagree with the statement that it’s conceivable that there are lots of universes with differing fundamental constants in all of them?”
Peter answered: “Sure, it’s conceivable that there are lots of different universes with different values fundamental constants. It’s also conceivable that Ed Witten is an alien, that we live in a Matrix controlled by evil supernatural beings, and that the Reverend Moon is the son of God. But there’s no evidence for any of these things (OK, maybe for the first one….).”
Please note the keyword I highlighted, “conceiveable“, which is a string word since human brains are amazing thinking devices capable of conceive ANYTHING describable or even none-describable by human languages.
Put it simple, anything that is EVER uttered from any piece of mouth by any one, is certainly completely “conceiveable”, for if the idea has not been conceiveable by one of the brains, if would never haven been spoken out by one of the mouths.
But that is not physics at all. Physics strictly does NOT deal with conceivable concepts. That’s the domain of psychology, not physics. Physics strictly deal with Observable evidences only, not conceiveable ones. Any one not understanding this needs to see a psychologist, not a physicist 🙂
There is not any evidence for multiverse and logic forbid the very existence of such evidences. THIS universe is all we can observe and physics deal strictly with what we can observe in THIS universe only, not what we can conceive out of this world.
Quantoken
Hi Aaron,
Sure, it’s conceivable that there are lots of different universes with different values fundamental constants. It’s also conceivable that Ed Witten is an alien, that we live in a Matrix controlled by evil supernatural beings, and that the Reverend Moon is the son of God. But there’s no evidence for any of these things (OK, maybe for the first one….).
What really bothers me is not serious physicist’s willingness to consider the “multiverse” idea, but their willingness to adopt it without a shred of evidence, or even a reasonable hope for ever having evidence. The only reason for doing this is to evade the fact that the string theory framework is a complete failure as a TOE. Being willing to trash the entire scientific enterprise to protect your failed ideology is just pathetic.
“It’s not impossible”. Boy, we’ve really set the bar high haven’t we. The same argument could be made in favor of reincarnation, or mental telepathy, or alien visitation (paging Dr. Kaku…)
“I have a question to the phenomenologist who loves experimental data….actual high energy (I mean non-astro) data? If yes, what are the most interesting recent data and how did superstring theory help you or inspire your work on these data? ”
Its not that there’s new significant data (non-astro), it’s that explaining the existing data, within the context of so called ‘natural’ solutions to the hierarchy problem is already very hard. These include SUSY, and all sorts of composite, technicolor like models of electroweak physics (here i just name 4d approaches).
Each of these approaches has predictions for what the LHC should see, which hopefully we can disentangle.
The problem is that all these approaches to stabilize the higgs mass introduce lots of junk that then has consequences on all sorts of precision measurements and predicts particle processes we have not seen. one winds up using all sorts of tricks to avoid this problem, some of them where inspired by string theory and
extra dimensional approaches (themselves inspired by string theory), though they are completely four dimensional. Most tricks involve cleverly controlling how symmetry breaking
is communicated to the SM.
The fact that none of these solutions/tricks are particularly simple or elegant, is part of the reason people are now looking
to anthropic explanations of the Higgs mass. I my self have not really bought into this, but here’s how it goes:
for example, if you vary only the Higgs mass in the SM and nothing else, you can convince yourself that varying it even within a factor of ten or so of its current (estimated) value you quickly loose all of chemistry. you wind up with a universe containing nothin more complicated than hydrogen. obviously any life needs chemistry
and stable elements besides hydrogen – therefore, the higgs
mass is roughly what it is. Since you dont need to worry about stabilizing the Higgs mass, you now motivate electroweak physics by requiring for instance that there be a stable particle at the weak scale which can be dark matter. Within SUSY such an anthropic scenario has very distinct predictions for physics at the electroweak scale. it might be very hard to see at LHC because there are very few predicted particles and none of them interact strongly, so you need to get clever. there could be some possible indirect signals though. so this is an example of how anthropics motivates concrete testable predictions. of course it depends highly on what you think can vary (in this case the higgs mass) and what cannot, so it is certainly arbitrary.
Also as I mentioned, QCD data (some of it really old) about
various strong particles perhaps can be explained using
AdS/CFT type of models – there has even been some
success in this – even quantatative: predicting particle masses
and decay rates. This is for those of you who doubt holography will ever make conact with experiment – maybe it already has and we just dont know it yet.
However I agree that thinking of string thy as TOE in the traditional sense is probably silly and that a lot of misleading marketing is being done by the popularizers of this field.
on the other hand, it is true that explaining to the public the various theoretical ideas to come out of string theory and motivating the existence of the field using those is really a difficult task, since of course we dont know which of these ideas will ultimately be useful in explaining data somewhere down
the line.
“I’m not willing to admit any hypothesis about how the universe works unless I’m provided with evidence for the hypothesis. And by evidence I mean scientific evidence: the hypothesis explains something about nature that can be checked. So, if the “landscape” can’t predict anything, it’s in the same category as religious belief. Not my thing.”
I didn’t ask you to say that the anthropic principle was the correct answer, just that it’s not impossible. Do you agree or disagree with the statement that it’s conceivable that there are lots of universes with differing fundamental constants in all of them?
I have a question to the phenomenologist who loves experimental data and has a high esteem of the accomplishments of superstring theory. Have you ever worked with actual high energy (I mean non-astro) data? If yes, what are the most interesting recent data and how did superstring theory help you or inspire your work on these data? Did it help you with understanding neutrino masses?
I agree with the comment that superstring theory was a reasonable thing to do while waiting for new experimental data. When the actual data starts coming, those string theorists who cared about “phenomenology” whatever it means these days, even if it’s such a nonsense as the anthropic landscape, will have a headstart.
Being smart also helps: if worse come to worst, Witten will be remembered for his 1976 paper on deep inelastic scattering.
In the past, it was thought that string theory was correct.
At present many people opines that it is not even wrong.
Some of us already know that is wrong. In fact, string theory pointed (and still point) in the wrong way in each research topic that i have studied: irreversibility, time arrow, quantum gravitation, molecular dynamics, catalysis, decoherence, relativistic invariance, nanothermodynamics, TFD, etc.
When I read a recent “high-level” paper by Witten, Vafa, Schwartz, Greene, etc. I find stuff abandoned even decades ago in the sophisticated fields that I and others work!
When will “string” theorists understand that their research is NOT the last theory nor the most advanced formulation of Nature?
To make my statement precise and unambiguous: there is not now any viable superstring theory explanation of the CC other than the anthropic one. I’m talking about what is actually known to be true, not what is wishful thinking. String theorists seem to have lost the ability to distinguish these two things.
You’re quite right that many string theorists hope that “one day” superstring theory will find another way to explain the CC. I didn’t deny this, but I was talking about what is known to be true, not about some what some people would like to be true even though they have no evidence for it. They also hope that “one day” superstring theory will explain the parameters and structure of the standard model. But this is pure wishful thinking, with a huge amount of evidence now built up that it can’t be true.
“You haven’t provided any string theory argument for the CC other than the landscape because there isn’t one (Ooguri, Vafa, Verlinde certainly don’t have one, I’ve read that paper).”
So have I. They don’t claim to have one. Nobody does, do they? I was just giving that as an example of a line of research that might, *one day*, lead to a theory of the CC that has nothing to do with the landscape. My point, which you are evading, is that many string theorists believe that there are other approaches than the Landscape. Your statement in the article was misleading.
“Susskind and many others are right about the fact that there isn’t one.”
How do you know? The truth is that you are engaging in wishful thinking: you *hope* that there is no alternative to the landscape because it makes string theory look bad. I repeat: a great many string theorists have no truck with the landscape. You know this, via your dear old friend Lubos. Why did you pretend to be unaware of it?
We know that some observations have anthropic explanations. The distance from the earth to the sun is the most common example. That’s not a fairy tale; it’s just how things are.
And this same anthropic theory explains Mercury, Venus, Mars, the asteroid belt, etc., how????????
The only thing the anthropic principle explains in this situation is why we live on earth and not on Mercury, Venus, Mars, etc.
Wouldn’t it be ironic if the correct ToE turned out to be essentially general relativity coupled to the standard model. After all, such a scenario would be in excellent agreement with experiments (though I realize that young theorists today disdain the E-word), and it would explain why so little beyond-the-SM physics is observed.
There are of course some theoretical problems with such a scenario, namely that QM and GR are incompatible and that the SM is somewhat ugly, especially in the Higgs sector. But it seems to me that these problems should be cured by some minor fix, rather than positing a plethora of unobserved phenomena and 10^500 unobservable universes totally different from ours. Finding the right fix is perhaps not so easy, but history teaches us that such a strategy has worked once before. In the 1930s people thought that QM was incompatible with special relativity, and especially electrodynamics. The small fix in that case was renormalization, which saved the situation without introducing any new physics.
Aaron,
I’m not willing to admit any hypothesis about how the universe works unless I’m provided with evidence for the hypothesis. And by evidence I mean scientific evidence: the hypothesis explains something about nature that can be checked. So, if the “landscape” can’t predict anything, it’s in the same category as religious belief. Not my thing.
Fyodor,
You haven’t provided any string theory argument for the CC other than the landscape because there isn’t one (Ooguri, Vafa, Verlinde certainly don’t have one, I’ve read that paper). Susskind and many others are right about the fact that there isn’t one. He’s also right that the whole field has been engaging in a huge amount of wishful thinking for years, although his wishful thinking is even more ridiculous.
Bottom line: you have an ugly, complicated, unfinished theoretical framework, and strong evidence that it either predicts nothing or something off by 120 orders of magnitude. You can bury your head in the sand and talk hopefully about how Ooguri, Vafa and Verlinde or some other recent paper will save the day, even though there is zero evidence for this. Why do you want to do this, other than to defend what looks like pure religious belief in an idea that doesn’t work?
A child’s question to his mother : “why did you have a child ?”
Anthropic answer : “because if I had not you would not ask the question.”
This is easily generalized : “why…(put a question here) ?” answer : “because if things were not this way you would not ask this question.”
More seriously, I think some “anthropic” arguments about, say, the coupling constants needed for carbon production make sense but are only an indirect and not very accurate way of extracting these coupling constants from the experimental data.
“If you have a string theory argument for the value of the CC other than the anthropic landscape one, tell us what it is instead of just writing “Who says” in response to my post. I’m the one saying it. If you think I’m wrong, tell us why so we can learn something.”
No, you aren’t the one saying it, Lenny Susskind is. You are talking as though LS were the accepted spokesman for string theorists on this matter, when you surely know that most string theorists do not approve of his dogmatic announcements on the Landscape. Quite a lot of us think that it is too early to say where the cosmological constant comes from, because we don’t understant supersymmetry breaking and because we don’t have a good understanding of dynamical spacetimes in string theory yet. To take but one example, I have been speaking to someone who is working on the recent ideas of Ooguri, Vafa, and Verlinde; he thinks we may be able to get some sort of understanding of cosmology out of that, but he admits that it is too early to say anything definite yet. And that is the attitude of most people in this field : they are far from believing that the Landscape is the only way to go. The theory is still too primitive for that. I can imagine someone saying to Lagrange and Hamilton: this is just fancy mathematics, what does it predict beyond the Standard Newtonian Model? What could they have said, except: “Restrain your impatience!”?
Aaron said: “But that last bit’s where you’re wrong. We know that some observations have anthropic explanations. The distance from the earth to the sun is the most common example. That’s not a fairy tale; it’s just how things are.”
The anthropic principle is extremely vacuous. You think it explains why the earth-sun distance is the way it is, ONLY BECAUSE you have inappropriately narrowed possible forms of life to the one similar to what earth bound life forms look like. You think life is only possible as a carbon based devices that evolves with the help of a chemical called water. That’s too narrow a definition of life.
I think a more broader definition of life would be anything that can carry, process and duplicate any form of information. Further I would define intelligent life as any thing that can carry, process and duplicate a sufficnet amount of information. But that definition, as long as the universe is big enough to contain a large amount of quantum information, it would breed certain forms of life, using certain chemical or other forms of matter.
Life really does not have to be carbon-based devices only. Why can’t silicon based devices by life as well?
Quantoken
Mr “” said:
“For example, the idea … that a QM system with gravity in some number of dimentions is equivalent to a non-gravity system in a lower dimension might by itself merit 20 years of string thy.”
What? That a kindergarten problem is what you spent 20 years on? Let me show you how trivial it is. To describe trajectory of a particle in N dimentions requires exactly N-1 equations, not one more and not one less. That’s kindergarten math, alright?
Now you put in one constraint, be it gravity or whatever. The constraint can be described by one equation. Plug it in and you have reduced the equation set fro N-1 to N-2. So you have successfully reduced dimentions from N to N-1. Simple, right? The rests are just technical details. But the math is rather simple!
Took me 20 seconds to describe it. If string theorists have spent 20 years to figure the same thing out. Too bad that’s a waste of their lifetime.
Quantoken
“If the string theory framework is not predictive, you’re right that doesn’t logically imply that it is wrong. But it does imply that it is something worse than wrong. It is not science, is completely useless, and is nothing more than a fairy tale.”
But that last bit’s where you’re wrong. We know that some observations have anthropic explanations. The distance from the earth to the sun is the most common example. That’s not a fairy tale; it’s just how things are. And, so it might be for the parameters of the standard model, if not through string theory, then through whatever is the correct theory of whatever.
If that’s true, there’s nothing you or I can do about it. No amount of dogmatism about the nonpredictiveness of the anthropic principle will change it. It’ll just be how the universe is.
And I agree with that dogmatism. The anthropic principle isn’t predictive. No amount of counting vacua will ever tell you anything about this universe. But I’m willing to admit that the anthropic principle may, nonetheless, be the right answer. Are you?
Holography is a nice idea. My phenomenological ami — have you ever heard about Cauchy’s theorem?
Unfortunately, physical systems are not necessarily analytic (unless you go far “beyond the standard model”), so holography will remain as a nice but a physically irrelevant idea. Take my word.
Jean-Paul
Certainly string theory has lead to a lot of interesting things, including a huge amount of interesting work on 2d CFTs, new insights into 4d QFT via AdS/CFT, quite a lot of beautiful algebraic geometry, and many other things. But what I object to is the entrenched ideology that a 10/11 dimensional string/M-theory can give you a TOE. This is the claim that is being used to sell the theory, and it motivates a large fraction of what string theorists do. But the evidence now is overwhelming that this idea doesn’t work.
If you want to understand string theory better and really see what can be gotten out of it, the TOE claims are a huge impediment. People have got to admit failure and move on, or they will be stuck for the next hundred years lost in the “landscape”. However you evaluate whether string theory is interesting, it is no longer interesting as a TOE. That idea has failed. But until people acknowledge that, the field won’t move on to something more interesting, and remain stuck in the hopeless dead-end it has gotten itself into.
I think you people are missing the whole point as to why string theory is interesting. It is interesting because it has been a great
toy model for many astounding theoretical ideas, whether or not it at the moment is directly linked to data.
I speak as a particle pheonomenologist who loves experimental data and certainly prefers writing papers about predicitve and testable theories. When confronted with difficult problems, theorists often try to solve much simpler, non-realistic examples which contain some features of the real problem but lack the complexity of the real world. This helps overcome the biggest challenge in theory – even knowing what is the right question to ask.
String theory has certainly proven to be a great laboratory for quantum gravity and QM in general, whether it is the right formulation for a full quantum theory of GR or not.
For example, the idea of holography (which you might have discussed) that a QM system with gravity in some number of dimentions is equivalent to a non-gravity system in a lower dimension might by itself merit 20 years of string thy. This idea (though first postulated indirectly without strings) was first fleshed out in certain concrete string theory examples where one can actually understand to some extent how it works. This idea has deep implications – changing our concept of dimension of a QM system, enriching our idea of how a QM system becomes classical, and changing our perspective on the data that QM gravity system requires.
Also, it has offered a method of building models which have qualitative agreement with features of QCD (a theory which has proven difficult to solve fully by any method thus far developed). My point is that string theory has changed our vocabulary for what are the right questions to ask in ways that we could not imagine before. And even if at some point this particular theory will be thrown out, i’m sure the toy examples it generates will further our understanding of fundamental issues.
As a side note, let me also mention that it has indirectly
influenced the creation of many mechanisms (completely garden variety four dimensional field theory ones) that are very useful in totaly predicitve, experimentally falsifiable theories of electroweak physics (which we might see at the LHC).
Of course this doesnt mean that all string thy research is useful – it is true that there are many people who dive into some techinical very specific aspects of the theory, rather than viewing it more as a lab for ideas, they take it very literally as a model for our world. i think though, that the really good string theorists are always seeking a general lesson, rather than some
specific solution in their work.
Phil Anderson been involved in the hiring of several generations of both particle theorists and condensed matter theorists at Princeton, and knows exactly what he is talking about.
Keep in mind that Anderson is about 80 years old, a Nobel Prize winner, and a good case can be made that he’s the one who discovered the Higgs mechanism. He was applying QFT to condensed matter problems during the 50s and 60s when most particle theorists had abandoned QFT. Over the years I’m sure he has developed some resentment at how particle theory has gotten much more attention that condensed matter theory, especially at Princeton. He’s famous for his opposition to the SSC and for his anti-reductionist “more is different” philosophical views. Over the last twenty years he has seen the Princeton particle theory group get completely taken over by string theory, a takeover facilitated by a huge amount of hype. He’s knows what it is like to really understand something new about physics and knows that string theorists haven’t been able to do this, despite all the hype. He has been upset and complaining about this situation for years.
Whatever you think about him, he’s someone who definitely is honest and definitely is honestly telling you what he thinks. He’s old enough and famous enough that he doesn’t need to worry about who he might offend by speaking his mind.