The string theory anthropic landscape point of view has now become so widely accepted and entrenched in the particle theory community that various people are making their claims about having had the idea first. The standard first paper that people generally reference is Leonard Susskind’s February 2003 The Anthropic landscape of string theory, which now has 243 citations. Susskind claims credit at least for the “Landscape” terminology in his recent book.
Last month Dutch string theorist Bert Schellekens posted a paper on the arXiv entitled The Landscape “avant la lettre”, in which he claims credit to some extent for the idea. He is quite enthusiastic about the Landscape as a paradigm shift and a new way of doing physics:
… I think even today we are only in an intermediate stage of a very slow shift of opinions regarding the objectives of our field. Although landscape ideas and even the anthropic principle are now at least discussed, it seems to me that the importance of the landscape is still severely underrated. I have tried to express my enthusiasm about the recent progress during seminars, but apparently with little success.
Schellekens claims that:
My own thoughts in this direction started around 1987. The year before I had published a paper with Wolfgang Lerche and Dieter Lust. Like other authors at the time, we found large numbers of four-dimensional chiral string theories, but much more than others we made a point of strongly emphasizing the non-uniqueness of the result.
He goes on to say that already back then it was clear to him that string theory was sending the message “if we find one vacuum we are going to find a huge number of them.” He recalls that when he was working at CERN in the years before 1992 he was promoting the anthropic string theory landscape idea and encountering a lot of resistance, often from people who now tell him that they had always been saying this kind of thing.
In 1998, at the occasion of his inauguration at the University of Nijmegen he gave a speech on this subject in Dutch. In the arXiv preprint Schellekens reproduces the Dutch text of his speech, together with an English translation. He notes that he used the Dutch word “landschap” in the text, although he mostly referred to the landscape using the Dutch word for a “mountain range”.
Schellekens admits that string theory may not be correct, but he says that string theory implies the landscape, so for string theory to be correct the landscape must exist. His only comment indicating that this might be a problem for string theory is that
…the unexpectedly huge size of the landscape is making it a lot harder to convince ourselves of that.[e.g. the correctness of string theory]
He does admit that back in 1998 he expected the size of the landscape to be much smaller than it now appears to be, smaller than the 1080 vacua that, uniformly distributed, could cover all possible values of the standard model parameters to the accuracy that we can measure them. So he expected that one would be able to somehow check string theory by seeing if one of the vacua agreed with the real world. Now that the number of vacua seems to be vastly greater than this, eliminating any reasonable hope of checking string theory this way, for some unfathomable reason his enthusiasm for the idea is undiminished if not intensified.
If you just can’t get enough of landscape discussion, there are recent blog entries on the topic by Sabine Hossenfelder and Alejandro Satz.
Update: The last-gasp hope for getting a prediction out of the landscape is that there is some useful structure in the landscape, so that it doesn’t densely cover all possible standard model parameters. Washington Taylor and Michael Douglas have been looking for such a thing amongst vacua, trying to find some correlations between properties of these vacua. For more about this, see Taylor’s web-page. Lubos has a blog posting about all this, in which Taylor explains the philosophy:
If we find 5 models with features X and Y of the standard model which all have feature Z which is not yet observed it is not very definitive. If we look in different parts of the string theory landscape and find that all 1020 models we know how to construct with features X and Y of the standard model have feature Z also it begins to carry some weight as a possible prediction.
So far, as you might expect, since there is no known reason for such correlations, they haven’t found any. Lubos reports:
Wati’s result in his particular examples was that there was virtually no information in the correlations: the difference was one bit and the distributions of different quantities were essentially independent Gaussians.
and goes on to rant:
Surely the physicists have not been working for 30 years to extract 1 bit of information – whose probability of being correct is moreover 50 percent. Even if there were any correlation, I would probably find such a correlation physically uninteresting. We know for sure that some of these correlations would agree with those observed in the real world, and some of them would not.
What will you do with this probable outcome? Will you overhype the “successful” patterns as evidence that the landscape reasoning is good, while you will be silent about the “unsuccessful” ones? I would count this activity as a part of astrology or catastrophic global warming theory, not physics. It’s frustrating to see that this is what is apparently being intended.
I wonder whether the people who were producing the very convoluted microscopic theories of the luminiferous aether in the 19th century really believed that this was the way to say anything new about physics – or whether most of them did these things just to do something and keep their jobs. Einstein took over in 1905 and showed not only that the aether was a ludicrous fantasy – but moreover, the absence of the aether is one of the basic principles that underlies his relativistic revolution in physics. Today, all of us – except for those in loop quantum gravity – know that the aether is a silliness that is not realized physically and that was never well motivated.
My feeling about the random model building and random model guessing is somewhat analogous to the random construction of the aether from gears and wheels. We’re missing something and we should not fool ourselves into thinking that we’re not.
Update: The Harvard physics department seems to be having quite a few seminars on the Landscape, and one participant reports:
A funny aspect of these discussions is that one can’t quite distinguish which of the considerations are jokes and which of them are meant seriously. At least I can’t distinguish them.
It’s our friends’ internal problem to decide who should be credited. I think that it’s some priests in the Catholic Church who should be credited for having discovered the idea a long time ago. At any rate, I don’t think that the originator of the anthropic idea has anything to be proud about, so it is not quite clear to me why anyone should be bitter about not being the first one who discovered this “great” idea.
One man’s junk is another man’s treasure.
From a historical perspective, how fast did the aether idea fall out of favor a century ago? Was it dropped like a rock suddenly by many physicists, or did it gradually fade away slowly into irrelevance over many years?
In this case, Lubie’s junk is also my junk.
Q: Why did the chicken cross the road?
Anthropic answer: In the other 10^500-1 universes it did not, but we happen to live in the universe where it did, even though we have no idea why.
JC asked when ether theory went out of favor. Basically when Einstein introduce SR. But Einstein himself reintroduced the ether in GR. Read “Einstein and the Ether” from Aperion Pub.
The ether is still being worked on actively, especially in Russia and China.
Actually Chris, that’s not the Anthropic principle, it’s the closely related Pouletropic principle. It subject of an upcoming paper by Dimopoulos and Arkani-Hamed that purports to solve the chicken-egg paradox.
Peter,
One can argue that the first glimpse of the landscape is in Narain continuous infinity of heterotic string compactifications.
When was Narain’s paper? 1985? 1986? That is definitely before Schellekens paper.
Narain does not talk about a landscape, but it was very clear (at least to me) that there were infinitely many string theories in 4 dimensions.
I should have left an example:
http://redshift.vif.com/JournalFiles/V13NO2PDF/V13N2DMI.pdf
Please, no more about current theories of the aether. The landscape is depressing enough.
The chicken-egg “paradox” ways always trivial to solve. The egg came first. Dinosaurs laid eggs.
Lubus: I would hope you have enough knowledge of PHYSICS to realize your statement: “Today, all of us – except for those in loop quantum gravity – know that the aether is a silliness that is not realized physically and that was never well motivated” is just nonsense.
If , as in those days, you believed in Maxwell and the wave equation, it was a VERY well motivated question to ask ‘what is it that is waving’ when light waves (not photons) propagate.
Einstein realized that in General Relativity, the notion of an aether was perhaps not so simple and not so easily dismissed.
But, out repect for Woit’s request for no more aether discussion, you will have to excercise your own initiative to discover what Einstein thought in that regard.
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dear Schellekens, Woit and Susskind,
I realized that string theory is useless when I was a student. My priority is clearly proofed by the fact that I do not have any stringy publication, not even a blog.
The Michelson-Morley experiment was performed in 1887, and Einstein formulated SR in 1905. However, H A Lorentz kept believing in the aether long after that.
Even if LHC becomes the Michelson-Morley experiment of supersymmetry, many people will continue to believe in SUSY and strings for the rest of their lives. (Note: a real prediction 🙂 )
Lubos: your agreement with Woit denotes deviationism. In order to save you from becoming the Gorbachev of String Theory, you are transferred from Harvard. Your next position will be in Kolyma, Siberia.
LDM: “If, as in those days, you believed in Maxwell and the wave equation, it was a VERY well motivated question to ask ‘what is it that is waving’ when light waves (not photons) propagate.”
Dear LDM,
my feeling is that I have explained rather clearly something that everyone in the field knows anyway – that the question “what is waving” was NEVER motivated and only the people who misunderstand not only relativity but also the rudimentary philosophy of physics can say otherwise in 2006.
The aether is a gigantic hoax, nonsense, and it has always been one. The only positive thing about the aether is that some of the people who believed it in the 19th century have also done some extremely serious physics, unlike most of their followers in the 20th and 21st century.
The reality of Nature is encoded in the set of mathematical equations – Maxwell’s equations in this case – and they are the full story. Naive mechanistic ways to imagine “what is waving” should only be created for children in the kindergarden or other people who have some intellectual limitations that prevent them from understanding that equations themselves can be and are fundamental and that fields can live in empty vacuum. Yes, there are gummi bears everywhere that are waving. The gummi bears must be there because some kids can’t live without them.
Adult physicists should be able to live without gummi bears. The electric and magnetic vectors exist directly at each point of vacuum, without any substrate, and it must be so, otherwise the basic postulates of special relativity would be compromised.
Dear Landscaper, your landscape is far from being the only reason why I plan something along your lines.
All the best
Lubos
What about the return of the aether in the veil of a “noncommutative” selection of a particular spacetime reference frame?
A simple change of terminology can affect the way we think about one and the same issue.
The term “space of CFTs (with certain properties)” hardly induces the same passion as “landscape of vacua (with certain properties)” does, does it?
At some point it would be great if we really knew what the “space of CFTs” actually is.
For the baby example of rational CFTs we sort of do.
Choosing deliberately unusual terminology we can reformulate a well known result as follows.
The landscape of rational CFTs is the category of lax functors from quivers into modular tensor categories.
Any more of this and I put the word “aether” in the kill-file that will automatically delete any comment containing this word…
Urs,
Mystifying with obscure mathematical terminology the fact that string theory has failed as an idea about unification because it is compatible with anything is not going to improve the situation.
Dear Bert,
the noncommutative parameter may break the Lorentz symmetry, like aether. It also breaks the rotational symmetry, unlike aether. Noncommutativity carries no entropy, unlike aether. It has no nontrivial microscopic structure, unlike aether. A noncommutative parameter may be viewed as a spontaneous symmetry violation in a theory that preserves the symmetry – and the original theory already carries all the excitations, unlike the space without aether.
To summarize: noncommutativity is not aether.
Let me be more general about the unmotivated ideas that can be classified as sick philosophical preconceptions. Take the sound and light. Sound is made of waves in the air. Is it natural to expect the same thing from light?
The answer is No. We only conjectured that there was a material that is waving – whenever there is sound – because we wanted to be able to:
* explain that sound can have different speed and other properties in different environments and different inertial frames; the extra material whose properties can change helps
* unify sound with some previous physical theories that rely on the concept of the air, such as the theory of breathing and the theory of winds 😉
Neither of these motivations existed in the case of light. Light has the same properties in each point of vacuum, and as one can figure out by analyzing Maxwell’s equations, it has also the same properties in all inertial reference frames.
The second point is not applicable either because there is no other experimental reason to think that there exists something such as the aether; for example, there is no aether wind. To summarize, the aether does not explain anything and it violates the knowledge of physics at the end of 19th century. It was never motivated. It was always a philosophical dogma – a stupidity.
Something that Einstein realized pretty well which allowed him to overcome the limitations of other physicists of his time and the limitations of crackpots.
The same thing holds for dozens of other fantasies that billions of people believe for purely irrational reasons. For example, hidden variables. Much like the case of the aether, there are absolutely no indications that the correct predictions need some extra garbage (hidden variables) or that they depend on some additional assumptions that could depend on the position in space. Quantum mechanics works the same way in the whole Universe.
In both cases, we have some obviously universal laws – Maxwell’s equations with the principle of relativity and the probabilistic character of physical predictions – that seem to hold in the same Universe. This always strongly indicated, to any rational person, that it was a very bad idea to try to find a more “microscopic mechanism” for these phenomena. Any new structure that one adds beneath these systems – Maxwell’s equations or the probabilistic structure of quantum mechanics – will ruin the universal validity of these laws.
Of course, today we have much more specific ways to prove that hidden variables can’t exist (unless we want to believe that locality is just a gigantic cosmic hoax and unexplainable conspiracy) – but the previous paragraph was meant to settle down the fact that aether or hidden variables were never motivated by scientific arguments – they were always stupid dogmas of philosophers who wanted to impose their naive ideas on Nature.
But she can make fun out of all people, not just the simpletons. It is scientists’ task to listen to Her and see how She really looks like.
Best wishes
Lubos
Dear Peter Woit,
you have been saying these stupidities about the hypothetical “problems” in string theory for more than 20 years. You have been predicting that theoretical physics can be done without string theory for more than 20 years. Is not it time for you to admit that your predictions – and not only predictions, for that matter – have been a gigantic failure? How many more years do you need to see that what you keep on writing is just a pile of idiocies and that string theory is absolutely essential for any conceptual theoretical physics beyond the framework of quantum field theory? A century? A millenium?
Best wishes
Lubos
Lubos,
Quite the opposite of what you say, I find more and more people all the time agreeing with my point of view about the problems of string theory and its failure as an idea about unification. My predictions about this failure made many years ago are in the process of coming true and being widely recognized.
In contrast, the mystification is due to the fact that nobody really knows what the space of all CFTs is like in detail.
That’s different for the rational case, and there what looks like obscure mathematical terminology to people unfamiliar with it is actually the lingua franca which makes things transparent.
Sorry, but I must use the verboten word one last time. String theory has a very strong resemblance to the 19th century theory of vortex filaments in the e….
The descending back into chiral QFT (that is what Urs probably means by conformal QFT) does not give any autonomous support of the metaphorical interpretation of string theoretical target space. It is however true that the adaptation of the old Nelson-Symanzik duality to the chiral realm permits to demonstrate the existence of a temperature duality relation between a chiral thermal theory and its dual (which is also a thermal chiral theory of the same kind) of which the Verlinde relations are a special case (thermal duality of the zero-point function). Whereas in the case of Nelson-Symanzik the rigorous framework for duality was the Osterwalder-Schrader Euclideanization, the chiral situation (as a consequence of braid group statistics) requires a new more noncommutative Euclideanization (done in the setting of Tomita-Takesaki modular operator theory). In this case one can even show that the temperature spacetime permits a spacetime interpretation (but not that in terms of a torus as a living space of a chiral theory, that remains metaphorical).
None of these new deep insights gives any support for the target space interpretation in string theory (basically because string theory only inherits those vacuum fluctuations from the lower dimensional source theory and has no autonomous target vacuum fluctuations). And this, Urs, is precisely the reason why string theory appears so metaphoric and eerie to your QFT colleagues (and to me) at the University of Hamburg.
“string theory is absolutely essential for any conceptual theoretical physics beyond the framework of quantum field theory”
-LM
Whether or not it will be essential remains to be seen, as for now LQG provides an example of a (mathematically) well defined construction of alternative QFTs that in certain simple cases have been shown to be a generalization of flat spacetime QFT.
Whether or not you believe these extensions to be physically relevant is one thing, but it’s simply incorrect that String theory is the only known way to go beyonf QFT. It’s certainly the most advanced and has revealed the richest structures, but it’s not the only option anymore.
To Lubos,
thanks for this nice semantic attempt.
Dear Peter,
you find more and more people because your blog attracts crackpots and people with serious intellectual limitations. There are roughly 4 billion people in the world who have no chance to comprehend anything that goes beyond classical physics. You’re finding an increasing percentage of these 4 billion limited people because you are falling deeply in between average peasants in Namibia yourself. The more you will be falling, the more counterparts you will be meeting.
But that’s not the community I am talking about.
I am reporting about real physics as done now in 2006, with which you have almost absolutely nothing to do. It is now clear that string theory as a framework is the only way how to transcend the limitations of GR and quantum field theories. Informed people know it, ignorants don’t. Of course that the number of ignorants in the world exceeds the number of informed people, much like in the case of Darwin’s evolution which – as you should already know by now – is completely analogous to string theory, but science is not democracy. Evolution and string theory are “must” despite billions of people who find the theories troubling.
Physicists who matter don’t waste time with you and people who agree with you. Only I do because I was born into an even more ordinary anti-academic environment, compared to which you are relatively informed in theoretical physics, which is why I have the natural temptation to communicate these things because I am indeed troubled by the gap between actual science and what regular people think about it.
My goal was always to make not just myself but also everyone else to be more able to understand the right thinking that is necessary for science and that normally distinguishes scientists from laymen. Your goal has always been the opposite one: to confirm laymen that they’re not missing anything and they should not learn anything, and even to transform relatively intelligent people into hopeless laymen who can’t comprehend even things as elementary as the fact that quantum gravity can’t be done without string theory.
Best
Lubos
****
the 10^80 vacua that, uniformly distributed, could cover all possible values of the standard model parameters to the accuracy that we can measure them.
****
Is this a recent way of expressing the problem? Can anyone give an online cite for it? Thanks.
Lubos,
My blog isn’t at all aimed at laymen, and I suspect a much smaller fraction of its readership is laymen than yours. The majority of connections to it come from academic machines with names like *.physics.wellknowninstitution.edu, often with “string” somewhere in the wild-card. The people who are reading it and sometimes agreeing, sometimes not, are your colleagues at Harvard, MIT, BU, Brandeis, etc., etc.
Virtually nobody in the physics community except you and a few other fanatics thinks that string theory and the theory of evolution are analogous.
Dick,
The number comes from Schellekens article, quoting Douglas, and it’s probably in one of his landscape papers. It’s a rough estimate, just taking all the parameters of the standard model and looking at the accuracy to which they are known.
——-
“you find more and more people because your blog attracts crackpots and people with serious intellectual limitations. There are roughly 4 billion people in the world who have no chance to comprehend anything that goes beyond classical physics. You’re finding an increasing percentage of these 4 billion limited people because you are falling deeply in between average peasants in Namibia yourself. The more you will be falling, the more counterparts you will be meeting.”
——-
Is this what passes for scientific discourse in the string theory community?
Glad I stayed in astrophysics.
While I can not evaluate your general criticism of string theory,I think you are absolutetly right to call the “anthropic” idea pseudo-science, Peter.
What percentage of string theorists do estimate share your and Lubos’ view on that matter? Part of the problem seams to be that some legitimate science is also called “antropic”. For example Weinbergs “prediction” of the CC seams to be legitimate science to me (as an uninformed layman), but as an empirical measurement and not as a theoretical prediction.
It’s ridiculous that you have a higher percentage of academic physics readers. Last 100 visits (domains) from the last 80 minutes follow.
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Johan,
Based on anecdotal data and public votes at Strings 2005, I’d guess that older, more established string theorists split 50/50 pro and anti anthropic landscape, while younger people starting out are 4-5 to 1 against the landscape.
My take on the difference is that older string theorists who have worked on this for a while realize that there is no way to get a unique answer out of string theory, have given up on this, and realize that string theory implies the landscape and they have to accept it. Younger people who have swallowed lots of propaganda and not had enough time to learn just how bad the situation is, are still more optimistic about evading the landscape.
Schroer says:
“The descending back into chiral QFT (that is what Urs probably means by conformal QFT)”
No, Urs meant CONFORMAL QFT, specifically, rational conformal QFT.
“And this, Urs, is precisely the reason why string theory appears so metaphoric and eerie…”
Oooooooooh! Scary!
Oooooooooooh. Make it go away!
Dear Peter,
there exists no background for your unusual statements about the generation gap. But even if there were any generation gap like this, it’s not terribly important. There have been many generation gaps in the past – and incidentally the younger generation was right in many cases, in sharp contradiction with your silly suggestion that the more old or senile someone is, the more likely is she to be right.
What’s more important is that Nature is whatever She is. If a careful analysis of the physical laws implies that certain phenomena have a unique and deep justification, then we have to accept such a justification. If a careful analysis of Nature leads to the insight that some things in the Universe are essentially random, then they’re random, and the opinion of Peter Woit and hundreds of those readers who can be counted as limited simply can’t change this fact.
The only framework how we can ask these deep questions scientifically is the framework of string theory and everyone who knows something about insights of theoretical physics of the last 30 years, instead of just being brainwashed by low-brow weblogs of science-haters, realizes it very well.
This is the basic point about science that you are apparently uncapable to realize. You can’t order Nature to look the way you would like. If you don’t like quantum mechanics or string theory, it’s your problem. If you really hate the idea that the world according to everything we can say follows these laws, that’s too bad. Try to move into another Universe.
Best
Lubos
I mean full 2D CFT.
The landscape is nothing but the space of all 2D CFTs (with certain properties). This space is not well understood in detail. Except in the rational case. There we have a powerful theorem that tells us precisely what this space really is.
Concerning metaphorics: Target space is indeed metaphoric, in some sense, in perturbative string theory.
String Field Theory is an attempt to formulate the theory on target space. Some day people might find out how to rigorously formulate quantum SFT. Maybe. Currently all work in SFT is classical. (It’s “first quantized”, but classical at the “second quantized” level.)
When you demand rigorously constructed theories, string field theory does not exist for practical purposes.
But this is not what the discussion here is about. The discussion here is about the idea that correlators in certain CFTs are a “good” approximation to certain scattering amplitudes. (That’s the premise of perturbative string theory – be that right or wrong).
These days the extremely special case of 2-dim. conformal QFT (and its two chiral components) is often called conformal QFT which leads to confusione with higher dimensional conformal QFT. Whereas it is true that one knows less about higher dimensional conformal QFT, it is in no way less important/interesting.
The Maldacena conjecture starts with a alleged 4-dim. conformal QFT (to be more precise beta=0, which is the prerequisite (necessary, but not sufficient) for CQFT). There are by now convincing arguments that the landscape (the old fashioned meaning) of higher-dimensional QFT is at least as rich as that for 2.dim. (Todorov, Rehren, Nicolov…) and of course each one of those models has an interesting AdS counterpart. The correct reading of Maldacenas conjecture is not that SuSyYM has a AdS encoding, since there is a structural theorem that this is the property of any CQFT. The sociological anomaly which lead to those thousands of papers is that he specifically claims that that rather simple encoding has anything to do with gravity.
Sam, I am not holding you back to feel cozy with string theory but there are people who know a lot more than you who do not share your feelings.
Dear Bert,
whoever claims to be a theoretical physicist in 2006 and who simultaneously believes that conformal field theories are not related to gravity in anti de Sitter space is a crackpot, and thousands of laymen who try to pretend that he’s not a crackpot can’t change the fact that he is a crackpot.
http://www.slac.stanford.edu/spires/find/hep?c=00203,2,231
Could you also find a technical problem with any of the 4000 papers that show that your idea is an undefendable one? Or do you realize that your “arguments” are only good for listeners who have no idea about physics?
Best wishes
Lubos
Urs
using your terminology “space”, the space of any QFT is not understood, and among all such non-understood spaces (I would prefer the word models) the one of the 2-dim. CQFT setting is relatively well understood.
Let me also say that I appreciate your honest and on the whole correct answer.
But I honestly do not understand to which scattering amplitudes you are referring to (probably not those which Veneziano tried to understand with his dual model and which were abandoned by phenomenologists when it contradicted the data).
Lubos motl said,
“It is now clear that string theory as a framework is the only way how to transcend the limitations of GR and quantum field theories.”
That is partially true! In physics, string theory is so boring and ineffective that even cannot offer results offered from GR and QFT. In fact, string theory is useless for physical predictions. Moreover, it “predicts” tons of unobserved properties for Universe and is based in “many” incorrect technical points.
Where string theory goes beyond GR and QFT, in no doubt, is in marketing purposes, positions in academia, best-sellers for public, TV, interviews, grants…
String theory is also very useful in exoteric fields: multidimensions, aliens, time travelling, exotic brain behavior, telekinese, multiuniverses, God…
The contributions to marketing and exoteric fields is inversely proportional to contributions of string theory to real physics.
It is a kind of duality 😉
Juan R.
Center for CANONICAL |SCIENCE)
Dear Lubos,
I am a healthy sinner against the metaphorical messianic way in which you defend your beliefs.
Lubos,
Yes, from your data, I do have a higher percentage of academic readers. During the last 80 minutes, they have come from three different machines in physics.harvard.edu, so my readers this hour include two of your colleagues.
The whole list is too long to include here, but the past 80 minutes include connections from (besides the harvard ones, and often there are multiple machines connecting from some of these domains)
jhuapl.edu
nottingham.ac.uk
dmi.unisa.it
u-psud.fr
het.brown.edu
physics.niu.edu
rz.uni-karlsruhe.de
hw.ac.uk
jyu.fi
hi.is
fy.chalmers.se
csudh.edu
unco.edu
math.uni-hamburg.de
iu-bremen.de
cmu.edu
dur.ac.uk
lsa.umich.edu
uwaterloo.ca
ist.utl.pt
ucsb.edu
physics.sunysb.edu
cpt.univ-mrs.fr
jpl.nasa.gov
kuleuven.ac.be
ulb.ac.be
temple.edu
upc.es
mpim-bonn.mpg.de
utexas.edu
fnal.gov
princeton.edu
ujf-grenoble.fr
ias.edu
if.usp.br (Hi Bert!)
physik.hu-berlin.de
dms.umontreal.ca
saclay.cea.fr
uiuc.edu
vanderbilt.edu
cam.ac.uk
gla.ac.uk
sinte.edu
theophys.kth.se
physics.nyu.edu
virginia.edu
ufl.edu
gravity.psu.edu
washington.edu
usc.es
na.infn.it
anu.edu.au
physics.mcgill.ca
jhu.edu
ecm.ub.es
physik.uni-regensburg.de
math.uu.se
insa-lyon.fr
mathematik.uni-leipzig.de
physik.fu-berlin.de
cta.br
ps.uci.edu
lut.ac.uk
duke.edu
physics.ucla.edu
efd.lth.se
utu.fi
ox.ac.uk
math.psu.edu
ucl.ac.uk
fisica.edu.uy
pa.uky.edu
math.ohio-state.edu
ed.ac.uk
bris.ac.uk
Urs: “The landscape is nothing but the space of all 2D CFTs (with certain properties). This space is not well understood in detail. Except in the rational case. There we have a powerful theorem that tells us precisely what this space really is.”
That’s exactly off the point – this is how CFT people like you see the world 😉 The landscape is more than CFT (= perturbative string theory), because it encompasses also non-perturbative vacua, for which there is no world-sheet definition at all. For example, F-theory vacua form a very large class of vacua; those are intrinsically non-perturbative as the coupling constant varies over the internal space; I wouldn’t know of any world-sheet like formulation! Similar for M-theory.
On the other hand, vacua based on completely different world-sheet theories (like heterotic, type II and type I strings), can give identical space-time theories… so in order to understand the nature of the landscape of string vacua (should it exist at all non-perturbatively), it is essential to step beyond string perturbation theory (=CFT ) and especially rational CFT!
No, Peter, you can’t prove anything about the percentage by choosing the academic connections only. What you’re doing is not science.
Even in absolute terms, I have more visitors in the category in the last 80 minutes than you have.
My list only includes the first unique visitors per day. Here are those added in the last 60 minutes to the previous list. Also, if you look carefully at the lists, you will see that I got more harvard.edu visitors (5) in the same period, despite the fact that my counter only counts the first visitors per day.
1
cybercity.dk May 18 2006 12:29:53 pm 1 0:00
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NYU.EDU 12:29:30 pm 2 0:30
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wvu.edu 12:29:03 pm 1 0:00
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ntl.com 12:28:54 pm 1 0:00
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atlantech.net 12:28:19 pm 1 0:00
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cam.ac.uk 12:27:43 pm 1 0:00
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harvard.edu 12:26:55 pm 1 0:00
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pacbell.net 12:26:04 pm 1 0:00
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pol.co.uk 12:24:51 pm 2 0:00
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194.95.177.# 12:24:39 pm 1 0:00
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193.49.4.# 12:24:24 pm 1 0:00
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tamu.edu 12:23:45 pm 1 0:00
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194.95.177.# 12:23:41 pm 3 2:20
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194.95.177.# 12:23:20 pm 1 0:00
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shawcable.net 12:21:29 pm 1 0:00
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uni-leipzig.de 12:21:24 pm 3 0:59
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hw.ac.uk 12:18:20 pm 1 0:10
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elisa-laajakaista.fi 12:18:19 pm 1 0:00
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86.133.65.# 12:18:08 pm 1 0:00
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Princeton.EDU 12:18:01 pm 1 0:00
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149.167.119.# 12:16:52 pm 1 0:00
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cuni.cz 12:16:24 pm 3 1:56
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mesanetworks.net 12:16:09 pm 1 0:00
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194.95.177.# 12:15:42 pm 3 9:59
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203.110.243.# 12:15:41 pm 1 0:00
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t-dialin.net 12:15:14 pm 1 0:00
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comcast.net 12:14:35 pm 2 1:59
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cox.net 12:11:00 pm 1 4:27
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155.91.28.# 12:10:28 pm 2 12:55
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cuni.cz 12:09:39 pm 4 7:57
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rr.com 12:09:31 pm 1 0:00
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Stanford.EDU 12:09:30 pm 1 0:00
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verizon.net 12:09:24 pm 1 0:00
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globnet.md 12:09:11 pm 1 0:00
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161.24.47.# 12:08:24 pm 1 0:00
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139.68.134.# 12:05:18 pm 11 19:55
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rogers.com 12:05:16 pm 1 0:00
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cas.cz 12:04:47 pm 1 0:00
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200.27.72.# 12:04:22 pm 1 0:00
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bellsouth.net 12:03:27 pm 2 3:40
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comcast.net 12:03:16 pm 1 0:00
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193.11.195.# 12:01:48 pm 1 26:22
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ncsu.edu 12:01:06 pm 1 0:00
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cern.ch 12:00:50 pm 1 0:00
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cuni.cz 12:00:30 pm 1 0:00
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trieste.it 12:00:19 pm 2 15:17
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interbusiness.it 11:58:42 am 1 0:00
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umass.edu 11:57:57 am 3 1:38
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cornell.edu 11:57:17 am 1 4:10
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cuny.edu 11:57:08 am 1 0:00
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cornell.edu 11:57:01 am 1 0:00
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216.48.35.# 11:56:23 am 1 0:00
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dias.ie 11:55:42 am 1 0:00
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cinergycom.net 11:55:08 am 1 2:54
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bellsouth.net 11:53:58 am 3 28:16
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wanadoo.fr 11:52:43 am 1 0:00
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145.8.163.# 11:51:32 am 1 0:00
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comcast.net 11:50:05 am 2 6:55
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luna.net 11:49:02 am 1 0:20
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harvard.edu 11:47:57 am 1 0:00
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phy.hr 11:47:19 am 1 0:00
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pacbell.net 11:46:49 am 1 0:00
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12.186.76.# 11:46:44 am 1 0:00
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comcast.net 11:46:34 am 1 0:00
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147.62.42.# 11:46:22 am 2 1:21
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ocn.ne.jp 11:46:12 am 1 0:00
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uab.edu 11:45:45 am 2 2:03
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rima-tde.net 11:44:50 am 1 0:00
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rockefeller.edu 11:44:03 am 1 0:00
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hu-berlin.de 11:42:35 am 1 0:00
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ameritech.net 11:42:21 am 1 0:00
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24.244.153.# 11:41:54 am 1 0:00
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gc.ca 11:41:24 am 1 0:00
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216.226.180.# 11:41:23 am 2 0:00
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58.7.159.# 11:41:22 am 1 27:39
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rpi.edu 11:40:31 am 1 0:00
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harvard.edu 11:38:52 am 1 0:00
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tartu.ee 11:38:47 am 1 0:00
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196.27.82.# 11:37:33 am 1 0:00
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optonline.net 11:36:15 am 1 0:00
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williams.edu 11:36:00 am 1 0:00
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verizon.net 11:35:50 am 1 0:00
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bris.ac.uk 11:34:38 am 1 0:27
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link.com.eg 11:34:30 am 1 5:44
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harvard.edu 11:34:27 am 1 0:00
The insinuation I intended with my remark about the missing autonomous vacuum polarization was among other things to blame those string vacua which do not communicate on this crucial but unfortunately missing property (with other words this is the limit of the metaphor).
Dear MoveOn,
I agree with you. There are many points in the configuration space of string theory that can’t be uniquely reached from a perturbative description – from a 2D CFT. In this sense, the perturbative string theories described by CFT are just 5/6 of the boundary of the landscape, while the bulk of the landscape contains extra points. The fraction 5/6 is meant to convey the fact that M-theory with 11 large dimensions may be viewed as a boundary of the moduli space that has no description in terms of strings.
From the text above, one can argue that even if you include M-theory and F-theory vacua, you don’t quite have the full “bulk” of the configuration space of the theory – all these things are just ways to approach the bulk from a kind of “boundary”. The bulk contains points where all perturbative expansions are strongly coupled, the space is non-geometric, Planck/string-sized, and so on.
Best wishes
Lubos
Great list, Lubos, but my **ck is still twice as long as yours! Get a life, kids. There are better things to argue about than “whose readers have bigger brains”.
True. But that’s even less well understood.
(For sure, I wish I better understood it…)
One of the points I tried to make is that everybody is getting heated about the “landscape”, while its true nature is pretty elusive.
For instance, correct me if I am wrong, but isn’t it true that the tadpole cancellation conditions that are routinely checked in order to see if a background is consistent only guarantee a consistent effective field theory, not necessarily a consistent full worldsheet CFT with that target?
No doubt. On the other hand, for doing the next step it is always helpful to have fully understood the previous one. The joy of toy examples, you know.
To be more precise, given that a full 2D TFT is the same thing as a Frobenius algebra in Vect, and given that full rational CFT is the same as a Frobenius algebra internal to a modular tensor category, it is not too daring to extrapolate and guess that, in the end, general full 2D CFT will be found to be the same as Frobenius algebras internal to something still a little more sophisticated.