Tuesday, June 28, 2005 ... Deutsch/Español/Related posts from blogosphere

CNN about Witten

David Goss has pointed out the following article to me:

It is unlikely that my readers will learn too much physics out of it, but it's fun and it describes our task in a realistic yet pretty optimistic manner.

Sunday, June 26, 2005 ... Deutsch/Español/Related posts from blogosphere

Google's maps

Most of us have used a map server such as MapQuest, Maps.MSN, Maps.Yahoo, MapsOnUs.Com, and so on. Many of these websites offer directions from one place to another place. But Google simply has to be ahead most of the time, and therefore they created

Friday, June 24, 2005 ... Deutsch/Español/Related posts from blogosphere

Amsterdam: black hole entropy corrections

Many people who returned from Amsterdam explained that the topic of the subleading corrections to the entropy of black holes (coming from higher order terms in the effective action), black rings, and their relations with topological string theory and various dual descriptions has been the focus of roughly one half of the talks and discussions. It's a category of questions that has attracted a significant part of the theoretical physics community these days.

Analytical structure of S-matrix

I wonder whether a reader will have an answer - or even a complete answer.

Imagine the S-matrix of a quantum field theory. It may have poles. The resonances are always above the real positive semi-axis in the "k_0" plane - by causality - and there are images below the negative semi-axis of "k_0". It would seem very bad if a pole - or a branch cut - were located just below the positive semi-axis of "k_0". Such a pole would look like an exponentially growing resonance, and it does not seem to agree with the "i.epsilon" prescription which reflects the causality of Feynman's propagators, as Nima has also emphasized to me right now.

But what about the poles that are further from the real axis? Is there some constraint that there can't be any poles in the whole two quadrants of the "k_0" plane with different signs of "Im(k_0)" and "Re(k_0)"? Or is the condition simpler in the s-plane where "s" is the Mandelstam variable? What is exactly the condition and how can one prove it? The main reason for this question is that what I've believed is the analytical structure of the M-theoretical S-matrix in 11 dimensions - with a Z_3 symmetry - seems to violate these rules. If you know the answer, thanks in advance.

Wednesday, June 22, 2005 ... Deutsch/Español/Related posts from blogosphere

CSL-1: better spectra

Update: CSL-1 is not a cosmic string.

A short addition to the discussions about the conjectured lensing by a cosmic string:

They compare the spectra of the two images - CSL-1a and CSL-1b - and show that they're identical at more than 99.9% confidence level.

Meanwhile, Mark Jackson and I have seen the positions of the other potentially lensed objects in the neighborhood of CSL-1 and we were unimpressed by their seemingly chaotic positions; one would expect that they would be kind of aligned.

A previous article was about WMAP and cosmic strings.

Monday, June 20, 2005 ... Deutsch/Español/Related posts from blogosphere

Chaudhuri on the Hagedorn "myth"

This short note is closely related to a previous article about the work of Dienes and Lennek.

IMPORTANT NOTE ADDED LATER: Although the topic and the character of the conclusions of the paper by Dienes and Lennek on one side and Chaudhuri on the other side may look similar, there are very important differences that can make one paper completely correct, if they're (or, on the contrary, she's) lucky, and the other incorrect. Please don't assume that the validity of these two papers is equivalent. And please be aware that I believe that these are kind of interesting and well-done papers, otherwise they would not be discussed here.

Back to the original text.

Tonight, it is Shyamoli Chaudhuri who is "dispelling the Hagedorn myth" (incidentally, it was already in 1965 when Hagedorn suggested that at high enough temperatures, open strings merge into a gas of chaotic long closed strings):

She calculates the thermal free energy - apparently in a different way than we are used to (from Atick and Witten and related works) - to conclude that the exponential growth of the states with the energy does not exist. In section 2.1 she argues that the growth of the number of states with the level does not imply the same growth of free energy as a function of temperature (or the density of states with the total energy). The true growth is slower, she says, making the full expression convergent. Nevertheless, she finds a first order phase transition at the T-self-dual temperature.

Her basic argument similar to the Dienes and Lennek's paper: the correct one-loop torus path integral only goes over the fundamental region of the modular group which removes the dangerous region with small "Im(tau)" and makes, according to her beliefs, the integral convergent for any temperature.

Sunday, June 19, 2005 ... Deutsch/Español/Related posts from blogosphere

Light Milky Cosmic Strings

Have you heard about the excess radiation at the 511 keV line emanating from our galactic center? As announced in New Scientist, two physicists from Ohio argue that the positrons might be produced inside very light superconducting strings, whose tension is near the TeV scale (much lighter than the string conjectured to be relevant for CSL-1 and other recently discussed observations), by electromagnetic induction:

It's a bit confusing if a cosmic string behaves almost just like a regular piece of wire, but their mechanism may be viable under certain assumptions. At least, a new candidate explanation of the strong 511 keV line has been added to the list.

Saturday, June 18, 2005 ... Deutsch/Español/Related posts from blogosphere

Wolfram Publicon - math writing

I have not tested this program of Stephen Wolfram's company yet, but it seems very likely that many people will find it very useful for typing math in a WYSIWYG fashion - it may be the first time when a WYSIWYG program becomes more convenient than the direct typing of the source.

The program is a natural supplement of Mathematica. It is a natural user interface for LaTeX/AMSTeX, MathML, and other frameworks. A free trial is available and many universities may have it for free. My friend sent me a snapshot of his screen. Enjoy!

Friday, June 17, 2005 ... Deutsch/Español/Related posts from blogosphere

The Bogdanoff papers

A fascinating book on the Bogdanoff affair and the rest of physics: click and buy.

The book is published in French on January 24th, 2008 by Presses de la renaissance. See also the table of contents of L'equation Bogdanov.
One of the topics that has not been discussed on this blog yet is the Bogdanoff affair (or Bogdanov, if you use another spelling).

Let me remind you: Alan Sokal from NYU became famous because he was able to submit a paper on "Hermeneutics of Quantum Gravity" to a renowned journal called "Social Text" and published by the postmodern social science experts at Duke University. The paper was a continuous flow of nonsense: for example it argued that the value of PI changes with the amount of political pressure and discrimination. It flattered these social scientists and repeated some of their weirdest opinions about the nature of science and its interactions with the society. Although it had to be clear to anyone who has an idea about the world of physics that a physics professor could never seriously write these things, the editors simply published it. Once they accepted his work, Sokal simultaneously published another article that revealed that the paper in "Social Text" was a hoax.

Incidentally, Plato has pointed out that the process of writing lit crit articles has been completely automatized and some of the best postmodern essays today are generated by Postmodernism Generator. Reload and read a couple of them, they are very good.

Later, two French journalists and scientific comedians with Russian names, namely Gritchka Bogdanoff and Igor Bogdanoff (whom the French TV audience knows as geniuses from a certain TV show), published something in "Classical and Quantum Gravity" that many journalists promoted as the "reverse Sokal hoax".

Actually, the originator of the conjecture that the paper was another hoax was apparently no one else than John Baez. As of 2005, it seems pretty clear that this widely accepted conjecture - that the paper was a hoax - was not correct and it never had any experimental support; the only point supporting Baez's speculation was that he knew that the Bogdanoff brothers were also a kind of journalists and showmen.

I view such a sociological argument as an irrelevant example of silly discrimination because the journalists have undoubtedly the right to try to learn physics and contribute to it and there is no physical law that could make such attempts completely impossible although most of us feel that such an approach to becomes a physicist is unlikely.

Wednesday, June 15, 2005 ... Deutsch/Español/Related posts from blogosphere

Hep-th today

There are quite a few interesting papers on hep-th today and many of us, including Peter Woit, could enjoy them. Some examples:

  • hep-th/0506118 by Hamilton, Kabat, Lifschytz, Lowe. They use the example of AdS2 as a prototype for constructing the bulk local operators in terms of the boundary operators. One of their conclusions is that only operators at the points on the boundary that are spacelike separated from the given point in the bulk are used in global AdS.
  • hep-th/0506104 by Cornalba and Costa. They argue - well - that the closed time-like curves may be consistent with unitarity for "right" values of Newton's constant - or, equivalently, the angular momentum of the black hole (integer or half-integer). One may imagine that closed time-like curves are OK if their periodicity is a multiple of the wavelength, but it is tougher to preserve these special properties with interactions included. They argue that although the closed curves break unitarity order by order in perturbation theory, the whole result is OK because it is dominated by graviton exchange where the graviton has the right wavelength. It's hard to believe it, but they have some evidence.
  • hep-th/0506106 by Nieto. Matroids and M-theory - or M(atroid) theory. Nieto has written many papers about the subject. An oriented matroid is a finite set E of objects together with a function taking values in {-1,0,1} defined for every subset of E with r (rank) elements that is completely antisymmetric and satisfies other properties. Obviously, it is a kind of a discrete counterpart of differential forms or elementary simplices of homology, but how it can tell us something realistic about M-theory is not clear to me so far. Comments welcome, once again.
  • hep-th/0506110 by Emparan and Mateos. Virtually all calculations of black hole (or black "object") entropy in string theory reduce to Cardy's formula. They argue that it is possible to interpret this formula geometrically in the bulk using "Komar integrals" that are equal to the "dimension" entering the Cardy formula if one evaluates them at the horizon. Everything is about the 3D BTZ black holes that are kind of found in all calculable examples. The quantity that becomes the "dimension" is typically a squared angular momentum, and therefore the square root - that appears in the Cardy formula - can give you the Bekenstein-Hawking entropy. It's still not clear to me whether they argue that they understand why the result must be "A/4G" for all the known examples.

Tuesday, June 14, 2005 ... Deutsch/Español/Related posts from blogosphere

Computer models and tossing a coin

Is the following story from a different field something that we can learn anything from?

As described in a press release, a team of researchers from Oxford has published a work - one that should have been done a long time ago - in the journal Global Ecology and Biogeography.

What is their contribution? They were apparently the first ones in the field of climatic biodiversity science who had a great and original :-) idea: to actually test the models. So they imagined that they returned to the 1970s and took 16 current climate models - more concretely, models that predict the impact of climate change on biodiversity - with them, trying to predict the ranges where different species would be found in 1991.

In 90% of the British bird species, the models could not even agree whether their range would expand or shrink. In 10% of cases, the models agreed: in one half of these 10% of cases, the reality (as we know it in 2005) agreed with the models, in the other half, it disagreed. In other words, you could also toss a coin - or even better: ask someone who likes the birds - to make a prediction. The results would be equally solid except that you would save hundreds of millions of dollars.

Better results (75% success rate) are obtained if you choose the "right" subset of the models and decide "collectively", but I don't exactly know whether it is a well-defined algorithm or a joke.

Now, frankly speaking, climate bioscience has never really been a part of the respectable core of sciences (it was always rather a sexy fad), so it should not be surprising when it is identified as cargo cult science or a computer game. But can high energy physics take a lesson from this story?

Difference from high-energy physics

Well, any possible lesson is guaranteed to be very limited. The reason is that we seem to be sure - because of very good reasons - that whatever we know about the past decades in (experimental) physics is explained by the Standard Model and General Relativity. If we took these current theories - the counterparts of those 16 models - to the past, we would almost certainly succeed in our predictions of the past that used to be the future. We think that we have done this gedanken experiment hundreds of times.

But is there something to say about the beyond-the-Standard-Model physics? I think that there is something to say about the principles that are meant to direct our search for new theories, but that are independent of their technical details. This includes the problem of vacuum selection in particular.

For example, one may conjecture that the theory describing Nature should be the simplest theory that allows for the existence of life and satisfies some mild conditions - for example, it contains the last well-established theory as a subset (today, the term means the Standard Model). Or alternatively, another grand principle may say that whatever objects (or terms in the Lagrangian) whose properties we do not understand are fundamental objects and the relevant parameters are determined - or at least we should believe that they are determined - by chance or the requirement that the life exists.

If we returned to the 1960s or the early 1970s - much like the Oxford climate scientists - both of these grand principles would have simply failed. They would have failed to predict some particles and many relations between them. In my opinion, this is an indication that these grand principles are not good enough principles and are likely to be incorrect. Until we actually see some new physics, we must unfortunately rely on these semi-philosophical considerations.

At any rate, one should try to test various choices that have alternatives and various approaches - especially those that are expected to be studied for years or decades - against all past data we actually have. And we should always try to estimate how non-trivial our arguments supporting a certain claim - or even more importantly, arguments supporting a whole direction or paradigm - are.

Obviously, the situation of the climatic biodiversity scientists is much simpler. They should have compared the models with reality a long time ago, conclude that the particular models they had were useless, despite their efforts to make them realistic, and move on. And if no progress in constructing predictable models is made for decades, they should simply temporarily give up and start to think that a quantitative predictable science about their favorite subject is impossible. Our situation is more subtle because it is tougher to compare our thinking with experiments. It is more difficult to show that we are on the right track, but it is also more difficult to show that we are on a wrong track. But these two possibilities should always be studied in a balanced way, I think.

This also applies to string theory where the experiments are replaced by calculations of more concrete examples of something, and these experiments are meant to decide about the fate of more general principles that we want to believe. We have been convinced that the problem of quantum gravity has essentially a unique solution currectly called string/M-theory, and I am still convinced that there is a huge body of evidence that this statement is true if the words are properly defined.

However, being on the right track in the big questions does not imply that we will always be on the right track. The fact that many dualities between string theories and other mathematical structures seem to be obviously correct does not imply that all conjectured dualities are correct. The fact that a particular simple vacuum exists and is consistent does not imply that all proposed vacua - or even all vacua proposed by the same authors - are consistent and exist. We don't seem to ask these questions too often.

Five minutes for a duality

In the mid 1990s, we had the duality revolution. One of the defining features was the following law that Tom Banks explained to me:

  • If you can't show that a conjectured duality is wrong in 5 minutes, it must be correct.

Because Peter Woit did not have a sufficient capacity to understand an essential point, let me emphasize that the theorem above has been really true in the case of tens of important dualities, and the initial five-minutes-long checks were followed by roughly 10 years of other tests. And the dualities have passed all of them.

Unfortunately, this principle was also applied years after the revolution when it was already incorrect. The dualities between the highly supersymmetric descriptions are most likely to be correct because both sides of the duality are extremely constrained and most likely unique. Together with a couple of checks, this proves the story.

But are we really sure that these dualities generalize to the non-supersymmetric context, for example? Most of the constraints go away and the quantitative precise checks are usually impossible. Virtually all conjectured non-supersymmetric dualities (except a few exceptions in the topological context) are suspicious, and even those that are true may be true only because we define one of the sides to be dual to the other - while other equally consistent definitions may exist, too.

One can't really get a result for free and until one finds the correct theory that can be checked arbitrarily precisely, there is a principle of complementarity between the number of tools and possibilities that may be used to explain XY, and the probability that such a constructed explanation is correct. If we just decide do solve some of our problems by adding many new tools (or many backgrounds), it may help, but unless there are independent arguments, such a move also reduces the probability that the solution is correct. Only if an independent argument - that the probability of the model's being correct drops less than the amount of arbitrary assumptions and players we add - exists, one may talk about progress. Otherwise it's just a confusing violation of Occam's razor.

Hybrid mesons

According to Charles Seife's article in the June 10th, 2005 issue of Science, KEK has discovered two bizarre particles:

  • X(3872)
  • Y(3940)
The numbers indicate masses in MeV. The lighter one (which is a sharper resonance) is most likely a bound state of D0 and D0*, analogous to the nuclei that are bound states of protons and neutrons. The heavier one is more puzzling, and a leading conjecture is that it is an example of a long-sought hybrid meson, i.e. a bound state of quarks connected by an excited (QCD) string - excuse me - an excited gluon fluxtube. Its mass is less sharply well-defined and it often decays to J/psi which a bound state of mesons would not do. More mundane explanations have not been ruled out yet.

Monday, June 13, 2005 ... Deutsch/Español/Related posts from blogosphere

Lisa Randall in England

Lisa Randall is promoting her book in England where her advanced popular book, The Warped Passages, has been selling for a couple of days. Click the cover image above to access the book web page on the British Amazon.

But what I definitely want to recommend you is the

She is doing an excellent job, I think. They ask her a lot of difficult questions - for example why is the critical dimension of M-theory eleven. Some of the questions are dumb, and Lisa faces the difficult task to explain them the difficult concept of effective theory.

Those who are interested in recent Lisa's appearences in the media should also look at

Saturday, June 11, 2005 ... Deutsch/Español/Related posts from blogosphere

Blogs about physics

I recommend the intelligent readers to ignore this message because it is not too serious. Anyway, Google has become pretty good in finding various blogs about interesting topics in physics. You would not believe how many interesting blogs there are, for example

Friday, June 10, 2005 ... Deutsch/Español/Related posts from blogosphere

Why no new Einstein?

My guess is that this freely available web page contains the announced new text by Lee Smolin that was published in the newest issue of Physics Today and mentioned on the blog Not Even Wrong (where Peter Woit displays his harmony with Lee). While I agree with many of Smolin's points about the nature of Einstein's discoveries and with his call for independence, it is hard to subscribe to the policies he proposes or even the topics that should be supported by various agencies and "Einstein fellowships". Let me start with Einstein, his approach, and his flaws.

Einstein - a maverick and a mainstream physicist

First of all, it is indeed true that , the amazing guy who has totally revolutionized our picture of physics at least twice in his life, was a rather average person in many respects. Minkowski, his high school high teacher, certainly had a reason to call Einstein "the lazy dog". Einstein's poetry was mediocre and his violin skills were so-so.

Later in his life, Einstein showed his inability to understand the new conceptual breakthroughs, especially those based on quantum mechanics. Because I believe that quantum mechanics represents the single most profound revolution in the 20th century physics, Einstein's misunderstanding of its inevitability was a pretty serious imperfection. Nevertheless, Einstein was able to transform his flawed opinions about quantum mechanics into something that led to great insights (about the entanglement) later. On the other hand, if Einstein were only a person who disliked quantum mechanics, we would not be celebrating him as the ultimate intellectual superhero today.

The year 1905 was Einstein's miraculous year. But Einstein would also fail to be a full Einstein if he did not find anything else later. Fortunately he did. In 1915-1916 he finished general relativity. The observations of bending light made Einstein an international celebrity in 1919. Einstein had to struggle for 10 years before the light of GR emerged in front of his eyes. During the long, exciting, and frustrating period he had obviously made a lot of errors, and he needed a help from Marcel Grossmann. It is conceivable that Einstein could have problems to get a decent job today if he needed 10 years to write

  • "S = int sqrt(g) R d4x / (16 pi G)"
or something like that. ;-) Yes, one may think that Einstein was a bit lucky, too. But what I would like to emphasize is the following:
  • It is very hard to imagine that one can artificially construct or social-engineer a new Einstein.
I will discuss this point in detail later. There is one more thing about Einstein that Lee does not seem to appreciate:
  • Einstein was not a classical crackpot.
What do I mean? Although Einstein came from a completely different environment than the mainstream scientists, he was more than familiar with all existing fundamental physics of his time. He did not claim it was wrong. In fact, he viewed special relativity as a small update of Newton's and Maxwell's insights.

His interpretation of some of the key aspects of Maxwell's theory were actually more conservative than the mainstream, and he agreed with some of the big visions made by the leading physicists. He appreciated the principle of relativity - something that other famous physicists would also agree with, but they underestimated its importance. Einstein was also impressed with Lorentz's results about the vacuum Maxwell's equations. Lorentz was a well-established physicist and Einstein understood very well that Lorentz's re-interpretation of Maxwell's equation, with one electric and one magnetic vector in the vacuum only, meant that aether was dead. Unlike Lorentz, Einstein also realized that this suggests that the equivalence of different reference frames should hold even for electromagnetic phenomena - even if we try to measure the speed of light. The latter should therefore be universal.

We know the final wisdom: all reference frames are equally suitable for formulating the physical laws - especially Luboš Motl's reference frame :-). If you have a feeling that this frame plays a unique role in the previous sentence, note that all other bloggers are also unique, like everyone else. :-)

Einstein was able to put all these things together. He figured out that one must sacrifice an assumption - that the simultaneity of events is absolute - that the people before 1905 considered so obvious that they did not even know that it could be questioned. They did not have the idea to ask the question whether the assumption was right. Today, we know that it can be questioned, it should be questioned, and it is in fact incorrect. The theory that makes the simultaneity relative is correct and it nicely agrees with the previous theory in the non-relativistic limit.

Thursday, June 09, 2005 ... Deutsch/Español/Related posts from blogosphere

Commencement at Harvard

The commencement is back at Harvard and it's a lot of fun. Recall that in 2002, CNN focused on the new string theory graduates

because the agency was convinced that the string theorists were connected with intelligence.

Among the people who have just received their new degrees from Harvard, you would find not only the new lawyers, architects, medicians, future politicians, managers, artists, and scientists, but also

  • Edward Witten who does not need to be introduced to the multi-dimensional readers of this blog
  • Chuck Vest who has served, among other things, as a celebrated president of the best university on Massachusetts Avenue in Cambridge East from the Central Square
  • David Baltimore, a Nobel prize winner for Medicine and the current president of Caltech and a key person in research of retroviruses and transcription of RNA to DNA
  • John Lithgow, a famous actor who is gonna deliver a speech in the afternoon

all of whom were awarded by honrary degrees. But of course, the most important person on Harvard Yard was the President of the University. He had to confer all the degrees to the new educated scholars from all branches of human life. And he had clearly a lot of fun with the undergrads whose majority obviously love him.

The speeches were well-prepared; this comment also applies Alicia Menendez with her "Perfect Imperfection" among others. Our graduation ceremony at Charles University in Prague was much more formal - but still likable.

Before the lunch, the exercises were adjourned by the person who had the authority to do it: the Sheriff of Middlesex County who could also become a comedian if he wanted. ;-) Throughout the day, Harvard alumni of all ages - starting with the year 1921 (!!!) - are marching through Harvard Yard. They have also made generous contributions to Harvard: for example, more than 35 million dollars came from one of those "rich" years.

Summers' talk

President Summers has offered his global visions. Three centuries from now, what will be the most important event of the current era according to the future historians? Summers thinks that it will be the growth of the developing world, mainly Asia, and the ability of the U.S. to respond to these changes. Summers said that there were many fewer people losing their lives because of wars than at any time in the past; the GDP may grow by a factor of 30 in the developing countries in a single lifetime. At the same moment, the U.S. policies are misunderstood - and perhaps misunderstanding - for many people outside the U.S. This is why Harvard's policies towards the foreign scholars are important. Summers stressed the importance of Harvard students from abroad; the offices that Harvard is opening in Bombay and other places; the students' visits to other countries. What is a better place to study China than China, for example?

The thoughtful analysis of the world's cultures has proved to be important many times in the past. For example, our knowledge of anthropology has helped America to occupy Japan more efficiently after the war. ;-) Also, Gorbachev's aide called Yakovlev was once asked why was the Berlin wall torn down. It was partly because of his studies in the U.S. in the 1950s! Even if there were just a small glimpse of an influence, and I am sure there is, such a glimpse is worth of paying our money to these projects. The President has also announced many new activities of Harvard that allow anyone in the world whose parents are poor to come to Harvard without any support of her or his family.

Also, he explained that Google together with Harvard are working to digitize the whole content of Harvard's classical libraries.

John Lithgow

John Lithgow started modestly. He said that his speech was an extraordinary moment not only in his life, but also in the history of Harvard because it is the first time when an actor gives the main commencement speech. So what kind of wisdom can he tell us? Are you nuts? Would you expect wisdom from an actor? If he were a wise guy, he would never have become an actor. Nevertheless, Lithgow tried and people liked it. He told the new alumni to be creative, useful, practical, and generous. And he added a fifth rule: finish BIG.

So what was the punch line he offered? He was reading from his new book, to be published in 2007, that will be dedicated to the 2005 Harvard alumni. It will show the Dunster House as an example of a college, and the Harvard Crimson instead of newspapers. The book will answer to all question marks that the students may have had during their last semester at Harvard: the main hero is gonna be a female mouse called Mahelia or something along these lines. She decided to study science. Even though the mouse did not look particularly bright to me, her professor said that she was a genius, and eventually she becomes a bachelor of sciences.

Wednesday, June 08, 2005 ... Deutsch/Español/Related posts from blogosphere

Sidneyfest - videos and web

A few months after the Sidneyfest, an official website celebrating the conference was created; thanks go to Arthur, Barbara, and Marina. (And perhaps me.)

There are many interesting letters of those who could not attend, the guestbook, genealogy, and photographs. Actually, most of the photographs are still waiting to be posted, much like the videos of all the talks.

Monday, June 06, 2005 ... Deutsch/Español/Related posts from blogosphere

Deviations from Newton's law seen?

We just returned from a lunch with Markus Greiner and one of the very interesting rumors I learned from an experimental colleague of ours - who has also told me that the news is publishable (but I won't reveal his name so far) - is the following.

The most careful and respected experimental group in its field which resides at University of Washington - Eric Adelberger et al. - seems to have detected deviations from Newton's gravitational law at distances slightly below 100 microns at the "4 sigma" confidence level. Because they are so careful and the implied assertion would be revolutionary (or, alternatively, looking spectacularly dumb), they intend to increase the effect to "8 sigma" or so and construct different and complementary experiments to test the same effect which could take a year or two (or more...) before the paper is published. You know, there are many things such as the van der Waals forces and other, possibly unexpected, condensed-matter related effects that become important at the multi-micron scales and should be separated from the rest.

Their measured force at these multimicron distances is weaker than expected from Newton's formula. This is unusual because in most models, one expects the force to grow stronger at short distances. For example, in theories with two

(that motivated these experiments) and quantum gravity at 10 TeV, the two large dimensions should be about 100 microns in size. The gravitational law "1/r^2" should switch to "1/r^4" at shorter distances - it should become stronger. One can also add massive scalar fields, but the most typical expectation is that a force obtained from the exchange of a scalar field is also attractive (between objects with the same "scalar charges"); it would therefore strengthen gravity. Of course, a new (massive) spin 1 field would, on the contrary, lead to repulsive interactions. All these scenarios with new intermediate particles are problematic because we can ask: why have not we seen these messengers yet? In most contexts, one would need to make their couplings incredibly small - as weak as gravity - which also suppresses the messenger production. But in this case, in a sense, the new interaction is a manifestation of a new mode of gravity (like its KK modes).

Einstein symposium

Just a short comment. Some of our colleagues are participating on the Einstein symposium in the famous ancient Library of Alexandria in Egypt. The event focuses on the 100th anniversary of Einstein's miraculous year and the public lectures are primary; on the other hand, the meeting also features a conference for the experts organized by Edward Witten and co-organized by Cumrun Vafa. The website of the symposium is here:

Friday, June 03, 2005 ... Deutsch/Español/Related posts from blogosphere

Topological membranes

Martin Schnabl has pointed out a sequence of pretty interesting papers by people like Carlip, Kogan (who sadly passed away in 2003), Szabo, Ferreira, and others. Let me mention one of the recent reviews by Szabo:

The papers in this category elaborate the "holographic" duality between
  • the WZW model in 2 dimensions and
  • the Chern-Simons theory in 3 dimensions.
One of the goals is to formulate the worldsheet description of string theory - arbitrary conformal field theory relevant for string theory (or at least a rational one) - in terms of a three-dimensional theory that may be more fundamental. More precisely, one wants to use "massive" Chern-Simons theory that also has the Maxwell term and whose worldvolume theory describes a "topological membrane".

A success story of this proposal is that one to give a much more geometric and dynamical description of Verlinde's formula, Cardy's condition, and other things. The details of this approach are different from the "N=2" string strategy - the latter offers a higher probability to explain the exceptional duality etc. - but still, some of the results look nontrivial. There are many open questions, too. For example, the original of the conformal bc ghosts is not really understood.

Anyone is familiar with this direction of thinking?

Wednesday, June 01, 2005 ... Deutsch/Español/Related posts from blogosphere

Holland: 61.6 percent NEE

According to nos.nl and their nearly final results, 61.6 percent (according to exit polls, 63 percent) of the Dutchmen have voted the EU constitution down in their consultative referendum. In other words, most of them were "TEGEN" the document and only 38.4 percent were "VOOR". Note that 94 percent of the Dutch Parliament supported the constitution. I think that these two facts already indicate that there is something wrong about the way how the current political elite in Europe "represents" the population.

Figure 1: Dutch cows vote "BOO".

The turnout about 62.8 percent was safely above the 30 percent level that was necessary for the politicians to accept it (and higher than the turnout during the last elections to the EU Parliament), and the victory was well above the 55 percent that were needed to define a "clear result".

The Dutchmen had different reasons to vote against the treaty from the French, and many (but not all) of them are closer to my opinions:

  • they don't want the other countries to ban marijuana, euthanasia, and public prostitution in the streets of Amsterdam and other cities
  • they are not happy about the economic developments in the last several years when Europe was strongly influencing the Netherlands, and they feel that the euro has damaged them
  • they don't like that the Dutchmen are the biggest payers per capita contributing to the EU budget
  • they don't want the rest of Europe to determine the Dutch immigration policies which would become almost inevitable under the constitution because many believe that their country is already full
  • as a smaller nation, they don't want to be controlled by the biggest nations of Europe, and the constitution reduces the relative influence of the Dutchmen compared to the treaty of Nice
  • they think that the unification has been too fast and too uncontrollable
There have been several factors why the victory of the "NEE" camp has been stronger than predicted - and two of them are related to the results in France:
  • the Dutchmen were not afraid to be the first nation of mavericks - the French have already shown that it is perfectly mainstream to vote "NON"
  • some supporters of the constitution stayed home because they have simply given up the process
What should happen now?

First of all, we should realize that although the situation is unexpected for many people in Europe - who have apparently assumed that the result of every referendum must be YES and there is no reason to even prepare for a NO - it is not a disaster. As Vaclav Klaus said, Europe has existed for 50 years without any constitution and it will continue for 50 more years without a constitution.

The responsible people in Europe should obey the law and the international treaties. According to some of these treaties, the EU constitution is now a dead document. No doubt, the integration process of the EU will be slowed down. It is very irresponsible if some politicians try to indicate that the clear results in Holland and France may be neglected or circumvented. Such an approach would contradict the law, and it would provoke even bigger violations of the law by the other side, and so forth.

I find it reasonable to save the money for the referenda in the other countries.

In a couple of years, I am confident that there will be another, less ambitious and much shorter document that may be acceptable for most citizens of every country of the EU - but no one should assume that the ratification is gonna be automatic or a formality. Such a document should be roughly 10 times shorter than the draft rejected by the French and the Dutch. It should not say anything about the economic and other policies. It should by default allow the nation-states to control their immigration, tax, social, and other policies, and many other policies that the authors of the draft wanted to move to Brussels - but such a move was found highly problematic by the voters - should stay in the nation-states. The system should be flexible enough so that every member should be able to exit some of the individual policies if the national parliaments - or the referenda - decide so.

Most importantly, there should now be a serious discussion about all these things - a discussion in which all opinions must be heard and all worries must be seriously addressed. Do we really want to decide about XY together? Is it a better or a worse option? Does the unified Europe strengthen or at least preserve democracy?

Piano Man is not Strnad

Tomas Strnad appeared on Czech TV today.

I personally don't think that he looks like the Piano Man at all. Another theory has been ruled out and the identity of the Piano Man remains a mystery.

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