Landscape: floating correlations

Dienes and Lennek show a general difficulty with the statistically predictive approach to the landscape: the floating correlations. This problem has been known to me for some time and was a reason not to consider the statistically predictive landscape approach to be a promising one. Below, I also try to propose the opposite approach although some details will be missing. ;-)

If you want to statistically predict the probability "P" that e.g. a vacuum contains an SU(3) factor in its gauge group, you will find out that "P" is not really a constant but a slowly increasing function of the number of models "N" that you tried. Dienes and Lennek tell you much more.

Of course, if the number of all models in your ensemble were finite, namely "N0", then the probability "P", assuming the unrealistic democratic distribution, would be simply

• P = Nyes / N0

where "Nyes" is the number of models among "N" that have an SU(3) factor. The correct "P" would be obtained as the limit for very large values of "N" - the number of the models that you tried. This limit "N" goes to "N0" defines the extreme anthropic approach to the set of vacua. A reasonable measure of this kind only exists for a finite "N0".

In the numerical attempts to compute similar probabilities, "P" doesn't seem to converge to a constant for large values of "N". This simply means that if you consider a larger set of possible models, e.g. heterotic models, such a larger set must secretly carry an approximately label "I" that increases with "N", so that probabilities such as "P" above can depend on "I".

I used the letter "I" because "I" stands for the average irrelevance. My approach to the right vacuum selection is exactly the opposite one from the extreme anthropic approach: we should be looking at sets of vacua with the minimal possible value of "I". These are the most relevant vacua for phenomenology. If you look at a set of vacua with a small value of "I", it will typically be a small set and these vacua will likely to be relevant. Also, these vacua will look simple and/or special in some way.

The quantity "I" is positively semidefinite for all subsets of vacua and it is equal to zero for the set that contains the vacuum describing our Universe only. We should be looking at sets of vacua with the minimal possible value of "I", and it won't be hard to find the right vacuum then.

Unfortunately, there is not enough room in this blog article for me to write the full definition of "I". :-) Nevertheless, it is clear that some large sets of generic complicated vacua will have a large value of "I". Also, I tend to think that the sets of Calabi-Yau vacua with high values of the Hodge numbers will have a high value of "I", too. People shouldn't waste too much time with these vacua.

Also, a decreasing function of "I" such as "exp(-I)" is likely to appear as an additional prefactor in the Hartle-Hawking wavefunction. It is conceivable that the value of "I" may be determined by or correlated with the mass spectrum at low energies. For example, it is conceivable that low values of "I" are associated with theories whose mass spectrum has large hierarchies and/or uniform distribution of mass scales on the logarithmic scale. A pretty good feature.

In principle, we could just measure physics up to the Planck scale and decode the topology, fluxes, and other labels of the physically relevant vacuum from the experiment scale by scale. I never understood the point of talking about NP-completeness of the problems to find the vacuum from the known cosmological constant only. There are many other, arguably more important numbers about the real world that we can measure today and others that people will measure in the future. With a sufficient hierarchy, one can determine aspects of the stringy compactification feature by feature, or scale by scale. One new scale can tell you something about a throat, another scale can tell you about the shape of the compact Calabi-Yau, and so forth.

More generally, I think that the focus should be on finding the right vacuum - with a large "I" - instead of doing statistics of the wrong vacua. Also, there can hypothetically exist new processes in cosmology that suppress vacua with a large "I", and there can be additional yet unknown decay channels that will make the vacua with a large "I" unstable, decaying towards the more elementary, more fundamental, less "excited" and less "contrived" vacua with a small "I" that are conjectured to be more likely to be the right description of this Universe.

The homework problem:

1. Calculate the value of "I" for some heterotic vacua and KKLT vacua
2. Find the set with one element "{U}" whose "I" is equal to zero
3. Use the model found in 2. to calculate the masses of quarks and leptons. ;-)
   

Trick or treat?

You have the power.

The incredible shrinking senior senator from Texas

Some initial observations:

--If this is what is happening to her body, imagine what's going on with her brain.

-- Do we really need another preening, fawning harridan in Washington?

-- Most Republicans running for Congress are cutting and running from Bush as fast as they can. Not in Sugar Land, though. They eat this up like a dog eating another dog's vomit.

Three suggestions:

-- Turn off your TV so you won't be subjected to any more of the GOP's incessant attempts to control the minds of the poor fools like those gathered around the people you see in the picture above.

-- Ignore the Houston Chronicle, the Dallas News and the urban daily newspapers throughout the state. They have all veered hard to the right -- through the weeds and into the ditch -- trying to get their Republican friends re-elected. Update (11/1): This is what I'm talkin' about. It's so shameless I almost feel sorry for them, except when I note their plummeting circulation figures. I'm sure they're all sitting together in their respective boardrooms wondering why.

-- Vote.

Halloween: Stern review

Last year, the alarmists would offer us a cute movie ClimateMash about the oil-drinking ghosts and zombies in the White House who would increase the number of hurricanes and melt all the snow on Earth.

Since 2005, the hurricane rate has dropped to roughly 30%. The temperatures have dropped since 2005, too. The alarmists have once again understood that the data from the real world is neither their cup of tea nor their ally and they returned to what they are best at: really dramatic, falsifiable predictions of the very same kind that the "critics of science" expect from the physicists. ;-)

It's the Halloween Day, 2006, and we are offered another ClimateMash called the Stern review. It's time for them to return to the well-established paradigm of the climate alarmism, originally coined by a former German minister of information: a lie repeated one hundred times becomes the truth. The sky is falling again.

A newer set of links to critiques of the Stern report can be found here.

As William Connolley has pointed out, Stern's economic numbers don't seem to be right according to Tim Worstall. Roger Pielke, Jr., argues that Stern is cherry-picking. Nevertheless, Sir Nicholas Stern uses some miraculous math to argue that the cost of failing to act on the climate change is 3.68 trillion pounds - note the breathtaking accuracy of his result. ;-)

That's a very impressive number but what is not said is that the cost of trying to fight with the climate change is 10 trillion pounds. I, for one, would prefer to save 6.32 trillion pounds and even arrest some people like Sir Stern if necessary in order to make this saving possible: I think that spreading this kind of false alarm is a crime in the Czech Republic, so once Sir Stern appears there, the police should act.

Stern claims that the temperature increase will be 2-5 Celsius degrees. William Connolley observes that Sir Stern has probably rounded up the "consensus" numbers 1.5-4.5 Celsius degrees. That's not the only fraud in the report: similar problems occur with other numbers. James Annan, another climate scientist, doesn't like the Stern report either although one might conjecture that it is mostly because he is not sufficiently referred to by the report. ;-)

According to OPEC, the report is unfounded. The Australian prime minister John Howard has also dismissed it. He will not give up the natural advantages of his country and he opposes action that wouldn't include India and China. Bjorn Lomborg is skeptical about the conclusions, too.

Incidentally, Connolley who is a former alarmist himself, has also pointed out that whenever those 25,000 frozen Britons in 2005 are discussed, the climate change is never mentioned. The situation is very different in the case of heatwaves.

Finiteness of supergravity theories

After you finish this one, try other articles related to finiteness of N=8 supergravity

Green, Russo, and Vanhove argue that many more divergences in maximally extended supergravity cancel than some people could think. They're not the first ones who conjecture that the power law divergences could be absent in d=4 N=8 supergravity: Zvi Bern has employed the constraints of unitarity together with the twistor-like template for the amplitudes

• A_{closed} = Extrafactors x A_{open} x A_{open}

to argue that the d=4 N=8 supergravity could be finite in the very same way as d=4 N=4 supersymmetric Yang-Mills theory is finite. Green et al. re-check some old things and calculate new diagrams in maximally extended supergravity using the methods based on string theory and M-theory.



Let me start with a historical comment. In the early 1980s, many people - including Stephen Hawking among the famous ones to the public - would get excited by the maximally extended supergravity because the power of supersymmetry seemed enough to cancel the divergences and give a finite supergravity theory. It was already known that less supersymmetric supergravities can't generate a finite theory in d=4.

The N=8 supergravity itself is phenomenologically unacceptable and one must break SUSY to at most N=1 supersymmetry to get a semi-realistic theory. The coupling of gravity to the other forces may create new potential problems. Moreover, it was widely believed that all theories of gravity, including N=8 supergravity, had to be non-renormalizable in d=4.

Let me say a few words, clarified in a discussion with Martin Roček, about the counterterms needed to cancel the different divergences in d=4 theories of gravity.

One-loop level

At one-loop level, one generates "Riemann^2" divergences in the effective action that need a counterterm. This happens to be no problem in gravity, not even in pure gravity: the "Riemann^2" terms can be written as a combination of the Gauss-Bonnet topological term (the Euler density) that doesn't matter for perturbative physics plus a function of the Ricci tensor and Ricci scalar that vanish on-shell (and that can be removed by a field redefinition anyway). That's a kind of "kinematical accident". The situation is even better for supergravity theories. To see problems, we must go to two loops.




Two-loop level

At the two-loop level, the required counterterms are of the form of "Riemann^3".

With no supersymmetry i.e. for "N=0", Goroff and Sagnotti have calculated in 1985-86 the non-zero two-loop "Riemann^3" counterterm. In dimensional regularization, the required counterterm in the Lagrangian is

• 209 / (2880 epsilon) x 1 / (16 pi^2)^2 x ...
• ... x sqrt(-g) C_{abcd} C^{cdef} C_{ef}^{ab}.

Yes, this essential result showing that pure quantum gravity is already perturbatively inconsistent is cubic in the Weyl tensor. A nice surprise is that with any supersymmetry, even with N=1, two-loop calculations are gonna be harmless. It's because the effective action that you generate can be seen to be supersymmetric but the "Riemann^3" terms admit no supersymmetric completion. So the coefficients of these terms must be zero.

Three-loop level

At the next level, one generates "Riemann^4" terms. Because we have already seen at the two-loop level that the pure gravity is unusable, we only look at supergravities. These three-loop counterterms are believed not to cancel in "N=1" supergravity because no one sees an obvious reason for such a cancellation but no full calculation exists.

For higher supersymmetry, many options were plausible.

One should realize that even for maximal supersymmetry, one obtains a non-renormalizable theory above "d=4". The higher dimension you work with, the worse divergences you obtain. The terms of the kind

• R^{3k+1}

in 11-dimensional gravity arise from the corresponding diagrams in type IIA string theory with "k" loops or less. Note that the powers of "R" can only change by multiples of three because M-theory kind of depends on l_{Planck}^3 only: the M2-brane tension, M5-brane tension, and Newton's constant scale like l_{Planck}^{-3}, l_{Planck}^{-6}, l_{Planck}^9, respectively.

The k-loop diagrams contributing to "Riemann^{3k+1}" are clearly the most important ones. Note that at high values of "k", they will scale like "(2k)!" which is the dominant behavior of the volume of the moduli space of genus-k Riemann surfaces. All these higher-order terms kind of know about string theory.

Incidentally, I just realized a week ago or so that the dependence on the factorial means that if you try to resum the effective action, the minimal term in the resummation will go like

• exp ( -Riemann^{-3/2} )

in the 11-dimensional Planck units which is exactly comparable to the first M2-brane-instanton contributions! It's because the exponent goes like "typical_length^3/l_{Planck}^3". You again see that the 11-dimensional supergravity knows about the membranes i.e. M2-branes as the leading non-local objects contributing to the full physics of M-theory.

Green et al. now argue that in the maximal supergravity, the power-law divergences at "h" loops only occur in spacetime dimensions

• d > 4 + 6/h.

This happens to be exactly the same condition as you obtain from a maximally supersymmetric gauge theory, indicating that supergravity may be morally viewed as the "square" of the gauge theory with half as many supercharges as argued by Bern.

If you want to get rid of all power law divergences, you can see that "d > 4" is already making your task impossible. However, "d = 4" is exactly the marginal case. The argument above shows that the logarithmic divergences are probably the worst kind of divergences you kind get in N=8, d=4.

Moreover, if you combine the one-loop kinematical accident with unitarity and supersymmetry, it is more or less healthy to believe that the effect of all these logarithmic divergences can be contained as well as in the "N=4" gauge theory although no complete proof exists.

What does it all mean?

I think it would be fun if the maximal supergravity were UV-finite after all although supergravity is still far from being enough to learn everything we need to learn about particle physics from string theory. It would be interesting to see whether some other, less supersymmetric supergravity theories that naturally arise from string theory could lead to similar cancellations if the additional matter is taken into account.

A new argument supporting the importance of "N=8" supergravity would be a good news for the inevitability of string theory. Why? Because "N=8" supergravity makes the more-or-less manifest existence of 6 or 7 extra dimensions of string theory with all the usual physics of string theory rather obvious.

Let me explain why. Imagine that someone convinces you that the "d=4" gravity should always be completed as in N=8 supergravity or in a similar setup. The N=8 supergravity is not a random theory of gravity. It is a very concrete theory whose 70 real scalar fields live in the coset of groups

• E_{7(7)} (R) / SU(8)

Recall that 133-63=70. In this theory, the mysterious exceptional group "E_{7(7)}", a non-compact version of "E_7", is the global symmetry. Also, there are 56 "U(1)" gauge fields transforming in the fundamental representation of the exceptional group. They're in one-to-one correspondence with different types of charges in four dimensions: Kaluza-Klein momenta (7), wrapped M2-branes (21), wrapped M5-branes (21), and wrapped Kaluza-Klein monopoles (7). Recall that 7+21+21+7=56.

You can easily see that general transformations from this exceptional group don't preserve the quantization of the magnetic fluxes. Only a discrete subgroup of the gauge symmetry can preserve the lattice of possible charges. In other words, the full symmetry at the non-perturbative level is

• E_{7(7)} (Z).

In other words, once you have the "N=8" supergravity, you can automatically derive that the actual maximum symmetry of the theory at the non-perturbative level is the U-duality group of M-theory on a seven-torus. Note that the perturbative part of the physics doesn't care about the flux quantization. The perturbative part of the theory doesn't even force you to have any objects that are electrically or magnetically charged under the "U(1)" symmetries.

However, we have argued using various arguments based on string theory and quantum gravity that a "U(1)" gauge field must not only come together with some charged particles but these particles must in fact be lighter than "g M_{Pl}" where "g" is the gauge coupling. At this scale or above it, the pure SUGRA theory has to break down. The last place above which pure SUGRA must certainly break down is the mass of the lightest black hole microstate.

Assuming that the non-perturbative completion is unique, the maximum symmetry that happens to coincide with the U-duality group is therefore the real symmetry of the non-perturbatively completed supergravity. Therefore, the U-duality is there. The U-duality relates the momentum states with various wrapped M2-branes and M5-branes and the Kaluza-Klein monopoles. In the right limit of the moduli space - the space of vevs of the 70 scalars - you can show that the physics of these BPS objects inevitably includes light strings (wrapped membranes) of type II string theory, and the rest of type II string theory follows because the strings are inevitably interacting and their interactions are again uniquely determined by supersymmetry.

It is quite clear that the rest of physics of maximally supersymmetric vacua of string/M-theory may be derived from non-perturbative consistency of the maximally extended supergravity: that's one of the reasons why the SUGRA community has really merged with the string-theoretical community ten years ago or so.

Note that some critics of science don't distinguish perturbative finiteness from non-perturbative completeness: the latter requires extended objects, among other things, as seen for example in the argument involving "(2k)!" above or the argument about the existence of charged light objects under all "U(1)" groups. Also, the perturbative expansion never converges in normal field theories and the first non-perturbative effects that fix it necessarily occur at the same order as dictated by string/M-theory. Also, the extended objects are found in the SUGRA whether you like it or not: they are found as classical solutions.

I find this belief system about the structure of consistent quantum gravity theories very appealing because with some extra steps in the reasoning, it could lead to a proof that string theory with its extra dimensions (or an equivalent) and all the extra extended objects is inevitable for consistent quantum gravity theories in "d=4" or higher: supersymmetry is necessary for a good UV behavior; that implies extra scalars and noncompact symmetries; these symmetries are broken by flux quantization to a discrete subgroup; extended objects must thus automatically exist in the theory; the only consistent way how they can interact is the way dictated by string/M-theory.

We kind of know that it is true anyway that string theory is necessary but it would be fun to have a semi-rigorous proof. One could expect that if "N=8" SUGRA is perturbatively finite, other limits obtained from other well-defined vacua of string/M-theory - such as the orientifolds relevant for the type IIA intersecting braneworlds - will be perturbatively finite, too. But other people could perhaps see a reason why it's not the case.

An early sign of MSSM

Concept via Clifford Johnson. ;-) It's not just Ireland where these encouraging signs appeared. The following one is from Poland:

More postpourri

-- the WaPo has an excellent contest called Midterm Madness utilizing an interactive Flash graphic where you can pick the seats in the Senate and House that you think will flip -- or not -- on November 7. Make your picks and submit for a chance at an AmEx gift certificate.

-- the poor mistreated corporations of America are banding together to fight back against the enormous and unrelenting legal persecution they have endured of late. See also Tom's blog for frequent commentary on this subject, usually focusing on the "harassment" of corporate executives accused of wrongdoing.

This is just about the most miserably obnoxious commentary proffered by conservatives of late (ever since they managed to take immigration nationwide, that is).

-- CNN's 'Broken Government' has been excellent; even the hit piece by Candy "Butterqueen" Crowley on the Democrats wasn't unwatchable, but the other parts of the series were examples of good solid political reporting. And among Houston media, KPRC's political page stands head and shoulders above the Chronicle and the other two broadcast outlets. Their on-demand video and coverage of local and state races is simply the best, by far. I rarely if ever watch their news, but the online resources they have assembled blow away the competition. Yesterday they televised "Straight Talk from the Candidates", where state- and county-wide party representatives were given 2.5 minutes uninterrupted to make their case directly to the voters. (This program will re-air on November 5, and is well worth watching.) Even for a political junkie like me, there are people running for office whom I have not seen nor heard speak, and this was an opportunity to gauge that intangible , emotional response to their face and voice.

Honorable mention goes to the Chronic's opinion and politics pages, and particularly cartoonist Nick Anderson's blog, deserving of special recognition for their interactive ease. The op page regularly links to local blogs, including this one, on topics not necessarily political.

-- the Republican television advertisements here are non-stop and nausea-inducing. Greg Abbott's commercial featuring his misuse of state resources just aired again. According to the Texas Penal Code Section 39.02, the state's top law enforcement officer may have committed at least a second-degree felony.

Who exactly is responsible for arresting, charging, and prosecuting the Attorney General when he commits a crime?

-- and don't miss the double edition of Sunday Funnies: Limbaughtomy and Election Day Countdown.

Telegraph: Lindzen and Eden on climate

Off-topic: the daylight-saving time is over in Europe and America. If you have not yet done so, return your clocks by 60 minutes and live one hour twice. ;-)

A pair of articles published in the Sunday Telegraph today bears a striking resemblance to some of the recent newspaper articles about high-energy physics. The two articles are written by

• Prof Richard Lindzen
• Philip Eden.

Lindzen of MIT is one of the most well-known climate scientists in the world. Eden is a weather correspondent of a newspaper and a press officer. He doesn't seem to exist in science, unlike Lindzen: using the polite words of a 2004 Nobel prize winner, Eden is a marginal figure. Nevertheless, the Sunday Telegraph misleadingly presents this pair of articles as a discussion of peers. Sorry but it is a discussion of a well-known scientist with a marginal figure.

Lindzen's introduction

Richard Lindzen explains some essential things about the climate: how much does the temperature change in general, what the errors could be, how much the temperature did change (or didn't change) in the last decade (incidentally, the Southern Hemisphere saw no warming in the last 30 years), why the effect of CO2 is sublinear and therefore the slope diminishes as the concentration grows, and why do the actual measurements seem to show that the climate models are incorrectly amplifying the effect of CO2: the actual data make it more reasonable to expect that the clouds actually reduce the effect.

He says that legitimate environmental goals could be achieved, especially if we saved the trillions of dollars from the CO2 hysteria. Finally, he stresses that the truth in science cannot be found by a repetition of pre-existing assumptions - and by unjustifiable and irrelevant allegations about a consensus. The main conclusion is, of course, that the global warming is no real threat: the temperature is as likely to go up as it is to go down.

You can see that everything about Lindzen's article is based on the actual observed facts combined with a more or less rudimentary scientific analysis of this data.

The alarmist answer

Eden's article couldn't be more different. The title is

• This is more rapid than at any time since the last ice age

which is an "improvement" of similar irrational hysterical headlines that other journalists have used throughout the last 100 years. Of course, the press officer's main statement is that the global warming is a real threat. But what is even more fascinating is the similarity with the journalists' take on high-energy theoretical physics.

Eden tries to teach Prof Lindzen what is the scientific method, no kidding. More precisely, he blames Prof Lindzen and/or other "skeptics" because their theories are "not testable". Well, I have already seen it somewhere.

First of all, it seems really strange if press officers are teaching top scientists what is the scientific method. Second of all, you can see that Eden uses this bogus argument about "testability" only against Lindzen but not against his favorite climate paradigms: he is exactly as one-sided and two-faced as those who have been recently using the same pseudoargument against high-energy physics. Third of all, the assumption that any particular statement about the long-term behavior of a particular quantity such as the temperature is unfalsifiable is simply ludicrous. The only difficulty is that the humankind will have to wait for a long time to see whether various theories about the climate are right or wrong. But the answer definitely exists.

For example, the conjecture that at the end of 20th century and the beginning of 21st century, the global averaged temperature increases every decade by a statistically significant amount has already been falsified because the temperature essentially didn't change in the last 10 years. All other wrong theories - which probably includes all hysterical fairy-tales about the climate - will be falsified in the future. It can't be otherwise.

Once predictions are made about particular numbers, they are always falsifiable, and unless these theories were derived by a rather careful theoretical analysis of existing experimental data and patterns, you can be pretty sure that the predictions are going to be wrong. Unfortunately, the authors of many bogus theories will never be punished for their alarmism because it will take years or decades to prove that they are wrong.

What Eden obviously means by the "scientific method" is alarmism itself. You must produce a hysterical theory - either a cataclysmic warming or a catastrophic cooling - otherwise you're not a scientist, Eden implicitly says. It is very analogous to the fringe physicists who claim that in order to do real science, you must produce theories in which quantum mechanics, unitarity, equivalence principle, Lorentz invariance, and other consistency rules collapse. Unless you don't offer such a far-reaching "theory", you're no scientist, they say.

One can also be nearly certain that the theories that are mainly supported by an endless repetition of journalists and their ad hominem, emotional, and quasi-philosophical pseudoarguments are likely to be among the wrong theories, too.

Is science over?

There is at least one more aspect that makes the alarmists and the critics of physics very close. Many critics of physics at the lower end of the spectrum of IQ would tell you that science or physics is over. The alarmists would like to tell you that the debate about the climate is over: it is essentially the same thing. In both cases, they want to replace a careful scientific analysis by a new era of irrational dogmas and superstitions. Of course, in reality, the statements about science that is over or a debate that is over is completely ridiculous, especially when we talk about questions that remain open and that are being actively investigated by the current generation of scientists. Unfortunately, these opinions are supported by powerful cliques of activists who have lost their mind.

Postpourri

-- In the "Blind-Hog-Occasionally-Finds-an-Acorn" department, the Houston Chronicle endorsed three of my very favorite people for the Texas Legislature: Chad Khan, Dr. Diane Trautman, and Dot Nelson-Turnier. Still they managed to blow it by endorsing Sherrie Matula's opponent. In fact almost all of the rest of their endorsements were, frankly, ones you should disregard.

-- The following two links are an example of the dichotomy that currently exists in my fair city. While janitors strike for $8.50 an hour and health insurance, the Tony-est restaurants in Houston are packed full of Republicans eating truffles at $300 a plate.

Seventy-dollar-a-barrel oil (even sixty, on its way up and down) and a 12,000 point Dow don't seem to have trickled down very far.

-- Early voting is way up across the state, but e-voting issues in predominantly Democratic Jefferson County remain a source of concern. Update (10/30): Dos Centavos links to this KFDM video detailing the notorious ES&S vote-switching machines, which had problems during the primary earlier this year.

-- Crime in Houston has not increased as much as conservatives would like you to believe. And it is not due to Katrina evacuees, either.

-- Karl Rove is apparently marshaling the goonbats in order to save the GOP from certain defeat. The last mystery left for this cycle -- besides, of course, whether our votes have been counted accurately or not -- is whether he will be successful. Fear just doesn't seem to be as effective a motivation this time.

-- The Saint Louis Cardinals defeated the Detroit Tigers to win the World Series, and the nation yawned. I didn't even see much gloating by Cards fans in the places I usually look.

-- The Houston Rockets could win the NBA champeenship this season. No, really.

-- Vaya con Dios, Joe Niekro and Red Auerbach.

George Johnson at KITP

Clifford Johnson has written the

• fifth teacup analysis

of the recent media-driven "controversy" about theoretical physics and as far as I can tell, he is right on the money. Clifford focuses on the talk by the journalist

• George Johnson (video available)

presented to the physicists at KITP in Santa Barbara. George Johnson - who is probably not Clifford's relative - has written some pretty good popular articles about theoretical physics in the past although some of them have had overhyped titles ("Physicists finally find a way to test superstring theory" is an example).

I remember that someone has convinced me to translate George Johnson's "Does the Universe follow mathematical laws?" into Czech when I was in the college. I disagreed with many statements of that article but it was an inspiring one so I did translate it.

Later, Johnson also added an "inelegant universe" in August 2006 among his rather famous pieces. Given the fact that The Elegant Universe is a great, balanced, and honest book that focuses on the actual content of science and its key results, avoids manifestly untrue statements, conspiracy theories, and ad hominem attacks, you may guess how an inelegant universe looks like. ;-)

Recently there have been roughly 30 similar inelegant universes - some of which have had even more drastic names - spread all over the newspapers. This wave has created such a vast and dramatically inelegant multiverse that even Prof Leonard Susskind must be jealous. ;-)

George Johnson was explaining why these things - and artificial boom-doom cycles, as he called them - occur. He has realistically painted the journalistic profession as a corrupt community whose main goal is to produce "stories" - caricatures of reality with heroes and villains - that can be sold to the average consumer, without much care whether the "stories" and their parts are true or not. He has also revealed that the headlines are not written by the authors of the articles themselves which was shocking for many innocent physicists in the audience. ;-)




He has also illuminated the method to write "balanced" articles: you can write a full page of lies and nonsense but if you add a sentence "but to be sure, something", then everything is just fine.

This morally mediocre nature of the journalistic profession inevitably leads to irrational waves of groupthink such as the recent one about string theory - but Johnson also offered some less drastic similar examples from the past. Some of the old, somewhat uncritical articles that have been written about string theory are just another side of the same coin. But I am personally convinced that no physics theory has ever been as over-hyped as the recent anti-physics non-theories promoted by the two slanderous books.

The curious physicists were asking him why he personally believed or paid attention to the weird statements of the two books. Gary Horowitz asked why they didn't write about even bigger stories that relativity and the 20th century physics was wrong and one of the new Einsteins - such as Mark McCutcheon - was right. Johnson answered that he didn't understand the technical jargon in the first part of the black book, so it had to be intelligent and reasonable (...). He also thinks that the voices of some of the outspoken condensed matter physicists must be extremely important for particle physics, and no one is obviously going to change George Johnson's mind about it.

The focus of the discussion - and the real source of outrage - was the book of Lee Smolin because its author is officially a part of the research community, unlike Peter Woit who was viewed as irrelevant by the participants.

Amanda Peet explained that it had to be obvious that the authors of those books don't apply the same standards to their theories as they use for string theory - and she uses the obvious inconsistencies of loop quantum gravity as an example. George Johnson offered a truly bold hypothesis that "he thinks that no one would call [the author of the blue book] a crackpot". A massive laughter, led by Joe Polchinski et al., explodes in the room, indicating a rather strong disagreement of science with the journalist. ;-) A physicist has challenged Johnson more comprehensibly: "Do you want to take a vote about it?"

The physicists who have talked to Johnson for a long time have clearly failed to explain him that there are roughly 4 additional distinguishable levels of knowledge between being marginally able to follow the presentation of the history of physics until the 1970s, and being able to produce scientific arguments that can influence the research of quantum gravity in 2006. Amanda Peet tried to tell Johnson that for any topic, you can find people with extreme opinions what's going on. As far as I can say, Johnson didn't get it.

No science-like hierarchy of knowledge exists in the profession of the journalists. You learn the grammar, some stylistic rules, and the wisdom that the point of the article is to create stories that are sold well, and you can become a journalist: you don't actually have to know any content. A skillful high school student may write an equally good article as his retired colleague. In physics, it is "slightly" different, and an average reader who just understood the material of the first part of the black book must be very intelligent and study for 5-10 more years to get to the actual level of current research in quantum gravity. Is that really such a difficult fact to comprehend, Mr. Johnson?

Some physicists, especially David Gross, were analyzing the intellectual dishonesty of the authors of the books collectively referred to as Swolin, especially the blue book whose author has manifestly understood why and agreed that his arguments about background independence and other concepts are incorrect, because of the AdS/CFT correspondence (where the background is not inserted) and because of other reasons, but he still prefers to pretend that he has not understood it yet.

One of the physicists offered a joke that became an instant classic:

• Do you need higher dimensions in order to be both one-sided and two-faced? :-)

Amanda Peet, Mark Srednicki, Gary Horowitz, and others were surprised why it was so difficult for the journalists to figure out that the recent books are nothing like a balanced view on physics but rather extreme screams in the darkness that are not supported by any real science. For example, Mark Srednicki argued that even the journalists should be able to see that someone is manipulating them if he uses the sentence "I can't understand why some people think that my book is anti-string" in the context of a book whose very subtitle links string theory and the "fall of science".

David Gross explained why the arguments of the critics are empty. They are either ad hominem attacks or dishonest comments about science or they try to create emotions about actual unanswered questions that are being rationally and legitimately investigated by the scientists right now.

He has also re-iterated his opinion that he always believed and he still essentially believes that the right policy is to ignore the weird voices in the jungle and assume that their existence will have no implications for science. It would be bad if the scientists were forced to participate in discussions with individua at the level of John Horgan about "deep" questions similar to the question whether science is over, among other bizarre things.

It is obvious that I don't blindly follow David's policy ;-), which has both negative as well as positive consequences, but I certainly understand where David Gross and other famous physicists with the same opinion come from and why they would never honor aggressive "critics of science" with an answer. The famous physicists' opinion is a qualified extrapolation of the old good times in which the foes of science were irrelevant, an era in which the enemies of well-established physical theories and the authors of incoherent alternatives could be humiliated or ignored by the scientists, according to the scientists' choice.

But if you listen to David Gross more carefully, you can tell that he is not so certain that his assumption continues to hold. We arguably live in the first decade of the human history in which the crackpots have become organized and they started to influence science and science journalism using political tools and intimidation.

The newest online technologies including the blogosphere have made such a thing possible. Also, the search engines are literally flooded with bogus statements about physics at junk blogs and other websites and many people, including journalists, often rely on these sources and they are completely unable to see that a bogus source is a bogus source as long as it respects most of the rules of grammar. Moreover, the organized cranks have absolutely no moral constraints. So for example, they erase every single reasonable review of the silly books. The last review of the blue book at amazon.com that was erased today was an insightful review of a non-string physics grad student.

Also, I completely agree with Clifford's assertion that one of the main goals of science journalism - a goal that is arguably more important than any technicality in particle physics - should be to explain how science actually works, how the arguments are constructed, propagated, and judged. How science differs from arts, politics, democracy, or war. It may be a difficult goal if the journalists don't have a clue themselves.

For example, George Johnson has made it very clear that he thinks that the popular books and newspaper articles don't belong to the public sphere but rather to the scientific process. He couldn't be further from the truth. Indeed, as long as he assumes that the most important things in science occur in the popular books and in the blogosphere, he will probably continue to write articles similar to his inelegant universe whose 95% have nothing to do with the actual scientific questions and discussions among the scientists.

Popular books are only interesting for active researchers to the same extent to which the researchers are parts of the general public. In the last 100 years, no important paradigm shift in physics was started by a book. Weinberg's "First Three Minutes" are the closest thing to a counterexample you can find because it has really stimulated research of the nucleogenesis, among other things.

Johnson has, in fact, explained why he thinks that some essays of condensed matter physicists about theology don't belong to the public sphere: he defined the public as those who don't care about string theory one way or the other. ;-) The audience has understood this description of the public as a good joke except that Johnson was clearly serious. ;-)

Finally, I want to say that some people propose various speech codes to fight against various undesirable tendencies in the broader discussions about science. These suggestions should restrict not only Swolin et al. but also scientists like Leonard Susskind. I disagree with this suggestion because it is against freedom and moreover it is unworkable because there will always be people who won't follow the rules even if they're good. Instead, the right situation should always allow anyone to do and say anything, but there should exist balanced mechanisms that naturally regulate what's going on. Do you want to write a book that rejects most of the scientific lore and attacks most of your colleagues, without having a good alternative? You can try but if something is wrong or dishonest about your writing, it will be exposed.

The fact that the "critics of science" have higher influence over the media and public perception of a scientific field than the Nobel prize winners in that field indicates that something could be wrong about the existing mechanisms of checks and balances.

Abbott spends taxpayer dollars on his TV ads

Which is a big fat violation of the law.

WFAA in Dallas reports, and pulls no punches.

For those of you unable to view the video, here's the summary:

Three years ago and shortly after he was elected attorney general, Greg Abbott ordered the OAG to purchase video equipment worth $66,000, and hired a videographer at a salary of $70,000 -- all at taxpayer expense -- to record, among other things, arrests of alleged child predators (the tapes show armed agents invading a home and subduing a suspect) . These videos have been seen in his recent barrage of television commercials.

They are also available for viewing at his campaign website.

Tom Smith of Public Citizen is quoted in the WFAA report saying that the law is clear in these cases, and that what the Attorney General has done is illegal. Abbott refused comment, but his campaign chairman responded with an e-mail statement indicating the videos were "obtained" through the FOI act.

David Van Os had this to say:

"I'm not surprised. It is representative of how Abbott has used his office for four years, and that is to promote himself."

I can't really add any outrage to this except to ask, "Have you had enough?"

Update: The Associated Press picks up on the story, and the Fort Worth Startle-Gram runs with it.

Steven Pinker: less faith, more reason

In his thoughtful

• op-ed in the Crimson,

Prof Steven Pinker begins with some nice words about the Report on General Education: in fact, they are somewhat nicer words than what your humble correspondent would write, even in the decent context of the university newspapers. ;-)

However, Pinker's main points are the following two:

• university must also teach the inherent value of science
• university must be based on reason and not faith.

Concerning the first point, Pinker quotes a comment from the report that science and technology can be used both for good things as well as bad things. Fair enough, no doubt about it. But what is not written so clearly, Pinker argues, is that architecture and opera, among other examples, can also be used both in positive and negative ways.

Architecture creates both museums and gas chambers while opera has both uplifted audiences and inspired the Nazis. ;-)

Pinker offers this observation because he feels that the balance between science and technology on one side and superstition and ignorance on the other side is presented as a moral trade-off by the report which is entirely wrong. Everything that people create can have both positive and negative consequences; nevertheless there are other reasons why sciences, social sciences, and arts still have a positive value despite the ambiguous sign of their creative potential. Pinker explains that the person who can't appreciate the intrinsic cultural value of pure science - of the knowledge how the world works - cannot be counted as an educated person.

Pinker also argues that universities are all about reason and not faith - which is just a milder word for religion: there are many other institutions in the society whose goal is to approach the reality via religion. Note that this is clearly a topic that would divide the anti-hard-left coalition in the Academia. Some of our right-wing colleagues have, on the contrary, promoted the idea of religion in the curriculum and they even argued that the reason should be removed from the education of religion. I understand where they're coming from but I probably agree with Pinker.

Pinker also argues that religion is not the main force behind various conflicts in the world. Well, it depends how we define "main", "religion", and where you look. ;-)

Czechoslovakia founded 88 years ago

In the Czech Republic, the birth of Czechoslovakia on October 28th, 1918 is celebrated as a national holiday. In Slovakia, it is just a memorial day and they don't really celebrate it, with the exception of an unknown party called Civic Conservative Party.



Well, it wouldn't hurt. The birth of Czechoslovakia was arguably more important a date for Slovakia than it was for the Czech lands: it was the first time when the borders of Slovakia were officially drawn on the map. Before the era of Czechoslovakia, a territory inside the big Hungary that would be controlled by the Slovaks was an ill-defined, hypothetical speculation.



At the end of the First World War, the Austrian-Hungarian monarchy was in trouble. The key person behind the birth of Czechoslovakia was Prof Tomáš Garrigue Masaryk who became the first president of Czechoslovakia and he remained the leader of the country nearly for 20 years: he died at the age of 87.



His middle name was borrowed from his wife, Charlotte Garrigue, who was an American protestant and who became the first First Lady. A very intelligent woman. Disclaimer: the picture below was taken decades before the picture above so you shouldn't think that TGM was a pedophile! They were both born in 1850.



Daddie Masaryk, as the people called him, has played a key role for the creation of Czechoslovakia on the ruins of the Austrian-Hungarian empire. Masaryk used to be a maverick in the nationalist political circles. For example, as a member of the Realist Party, he has been claiming that the Královedvorský and Zelenohorský manuscripts from 1820 or so, alleged proofs of a rich Czech literature nearly 1000 years old, were fake: Masaryk came to that conclusion by a careful sociological analysis of the manuscripts' background. See also Leaders of mature nations. This statement of his has made most of the nationalists very angry. Needless to say, Masaryk was right as ultimately proven by detailed chemical analyses in the 1960s, decades after his death.




As the first president, TGM became the complete mainstream and his authority and approval rate was resembling autocracy - a hallmark of a truly working democracy. In the late 1930s, his death unfortunately coincided with the expansion of Nazism.

Back to 1918. TGM convinced Woodrow Wilson and other friends in the West that it was a great and deeply moral idea to create a democratic Czechoslovakia. Its independence was eventually declared in Washington, D.C. The arguments were based, among other things, on two valuable approximations:

1. Czechoslovakia would become a national state with one nation only, the Czechoslovak nation
2. Czechoslovakia, unlike Austria-Hungary, didn't have any significant minority that would be creating problems

These approximations had its limitations. Above some energy scale, the approximation (1) could break down because some Slovaks could have argued that the Slovak nation was a distinct nation from the Czech nation. Of course, whether or not there were two nations or one nation has always been a matter of conventions. The Slovak language was closer to the official Czech language than many other dialects of Czech. On the other hand, the Czechs and Slovaks had been politically divided for most of the second millenium: the Czechs were co-existing with the Austrians and Germans while the Slovaks had lived under Hungary. I personally always preferred to think about one Czechoslovak nation.

The approximation (2) neglected the German 30% minority that was actually a majority in certain borderland regions called the Sudetenland. Although the Germans enjoyed at least as good minority rights in Czechoslovakia as the Czechs enjoyed within Austria-Hungary, you may guess that such a huge minority becomes a problem as soon as a radical politician, for example Adolf Hitler, takes over in an adjacent country. And it did cause problems in the 1930s, indeed.

Nevertheless, Czechoslovakia has become an island of democracy, happiness, freedom, and optimism inside the rather problematic region of Central Europe for 20 years. It was also among the top 10 most economically advanced countries in the world.

In 1938, the German Nazis were able to split Czechoslovakia into Bohemia and Moravia (the Czech lands) on one side and Slovakia on the other side, while they occupied the Sudetenland. In 1939, the rest of the Czech lands became a protectorate, a colony of the Third Reich. The politicians in Czechoslovakia's allied countries, including France and Great Britain, were appeasing morons so they simply betrayed their smaller friend and allowed Hitler to help himself.

The Czechs chose a submissive position during the Second World War and they were doing fine in a quasi-socialist regime controlled by Berlin. Many people in the resistance movement were executed. The assassination of Reinhard Heydrich in 1942 - organized from London - became the only visible sign of the Czech resistance movement until May 1945. Three days before the war ended, some Czechs started a heroic backlash against the Third Reich. ;-)

In 1945, Czechoslovakia was liberated - mostly by the Red Army but partly by the U.S. army - and re-unified. Incidentally, the most Eastern piece of Czechoslovakia, the sub-Carpathian Rus, that was added to Czechoslovakia as an autonomous territory in 1918 after a successful referendum made among the immigrants from sub-Carpathian Rus to America ;-), this territory was separated from Czechoslovakia and attached to the Ukrainian Soviet Socialist Republic. The sub-Carpathian voters in another referendum in 1945 have thus reduced their granddaughters' GDP per capita by an order of magnitude. ;-)

A slow march towards communism started after the war. Communism officially took over in 1948 and lasted until the Velvet Revolution in 1989, with a small freedom break in the middle, during the 1968 Prague Spring. The democracy in 1989 also strengthened the Slovak nationalist movement that eventually led to the Velvet Divorce in late 1992 when Czechoslovakia split up.

The two nations maintain extraordinarily friendly relations. Although the divorce was mostly driven by the Slovak sentiments, it is the Czechs who are currently more satisfied with the fact that Czechoslovakia has been deconstructed.

CFT/AdS and multiple AdS components

Ofer Aharony gave an interesting Duality Seminar about the

• CFT/AdS correspondence, massive gravitons, and connectivity index conjecture.

The unusual ordering of the acronyms, CFT/AdS instead of AdS/CFT, refers to the conjecture that for every CFT, there exists a quantum gravity theory on an AdS space.

Ofer views the opposite statement, denoted as AdS/CFT, to be obvious: one simply defines the CFT to be the set of all possible correlators among all possible local operators. This set of functions can be simply extracted from the scattering amplitudes of all physical states created on the boundary and interacting in the bulk of the AdS. Because the AdS space always has gravity on it, you always obtain the stress-energy tensor in the spectrum of the operators. Other consistency rules of CFTs probably hold, too.



The main statement of Ofer Aharony, Andreas Karch, and Adam Clark is that the opposite implication doesn't hold. One can construct CFTs whose dual doesn't deserve to be called "quantum gravity on AdS" despite the fact that you might think that "quantum gravity" without the CFT is so loose and ill-defined that any theory can be called quantum gravity.

The reason why some CFTs are not dual to gravity on AdS according to these three guys is that these CFTs can really be shown to be dual to gravity on the union of several copies of AdS - copies that are connected through the boundary conditions relating their AdS boundaries only.




Their examples involve the CFTs constructed in the following way. Choose a dimension of the CFT spacetime and two copies of a CFT that are originally decoupled. They have two different stress-energy tensors. Now, add a small coupling that relates them. Only the overall stress-energy tensor will be conserved. The anti-diagonal combination that generates the relative shifts of the "two" spacetimes will acquire an anomalous dimension and it will no longer be conserved. It will become a massive spin-two field or, using a different terminology, a massive graviton.

This interpretation of massive spin-two fields is analogous to their interpretation in the language of deconstruction. Every massive spin-two field is morally another metric tensor that acquired mass through a Higgs-like mechanism. Incidentally, they also do the bulk calculation of the mass of the anti-diagonal graviton and this calculation yields a result that exactly agrees with the anomalous dimension of the stress-energy tensor, using the usual AdS/CFT dictionary that translates the dimensions into masses. In the flat space, the limit "m goes to zero" is discontinuous. But in the AdS space, the limit turns out to be smooth.

They can show that even after these previously independent CFTs are coupled, the bulk interpretation of this coupling is only via the AdS boundaries. The particular examples include either

• two two-dimensional CFTs with an added (1,1) tensor coupling that is constructed as a product of a (1,0) current from the first CFT and a (0,1) current from the second CFT
• two four-dimensional theories analogous to the Klebanov-Witten fixed points, with a particular trace used as a perturbation

In both cases, the perturbation relating the two CFTs can be chosen to be exactly (non-perturbatively) marginal so that the conformal symmetry is preserved. The effect of the perturbation on physics may be shown to cause some correlations of the boundary conditions for the bulk AdS fields only but no direct interaction of the fields in the bulk. Even though the two CFTs share the same space on the boundary - they fully overlap - they live on different components of the AdS spaces.

Their reasoning leads them to conjecture that the set of all CFTs can be split to subsets with non-negative integer labels "n" that tell you how many copies of AdS space the dual gravitational theory has. For "SU(K) x SU(L)", a decoupled pair of two gauge theories, the value of "n" is clearly two. But they propose models where "n" is greater than one even though the theory cannot be split into decoupled subtheories.

They reasonably believe that if the gravitational theory can be interpreted in terms of a disjoint union of AdS spaces, there should be no other description of the same physics that involves one AdS space only. This leads them to argue that it is not true that every CFT has a dual gravitational description that involves one AdS space only.

I asked Ofer about the interpretation of "SU(15)" broken to "SU(10) x SU(5)" by the scalar vevs. You can integrate out all the off-diagonal, bi-fundamental degrees of freedom (W-bosons et al.) and write down the resulting theory as "SU(10)" combined with "SU(5)" gauge theory, with small corrections that couple them. Such a description will have a gravitational dual geometry composed of two independent near-horizon geometries. However, the effective theory with the W-bosons integrated out will break down at energies equal to the W-mass or higher. Still, the full theory is continuously connected to a theory whose dual manifestly lives on one AdS space only - the dual to the "SU(15)" gauge theory.

I asked Ofer whether he didn't think that this behavior was universal. Ofer argued that it was not. In the Klebanov-Witten-like examples, he argues that the deformed theory with the mixed interaction is valid up to arbitrarily high energy scales, unlike the theory with the W-bosons integrated out. The main possible loophole could be that there are some new operators with dimensions that diverge for "lambda=0" and that become finite for non-zero "lambda" (the coupling relating the two CFTs).

This effect would be analogous to the fact that there exist D-branes and other solitons and instantons whose tensions or masses or actions diverge in the "g=0" limit. Aren't there some operators dual to these heavy objects? If this is the case, then one could revive the idea that for every CFT, the physics of all interacting CFTs is qualitatively analogous to the "SU(15)" example and "morally", the number of AdS components is always one as long as you look at the theory with a high enough energy cutoff.

In other words, the different CFTs can be decoupled in the middle of the AdS space where the volumes are large - the infrared regime - but they always become coupled, even in the bulk, in the ultraviolated regime - near the AdS boundary where the volumes are large. Note that Ofer et al. essentially agree that the the coupling between the theories becomes important near the boundary but they always view such a relation to be nothing else than a backreaction reflecting the coupled boundary conditions at the exact boundaries.

Meanwhile, until someone finds the high-dimension operators of the KW-KW system mentioned above, Ofer et al. can legitimately believe that the set of CFTs sharply splits into classes labeled by integers "n" that tell you how many components the dual AdS-like bulk description has. That's a somewhat unusual statement to conjecture that every random CFT has this kind of an "index" called "n" but there is no completely obvious way to disprove this bold and interesting assertion.

Jacques has written about this topic here.

Slashdot is powerful

Special welcome for the nerds who want to know the stuff that matters. ;-)

Who could have thought that a modest link in the middle of a long article at Slashdot.ORG can temporarily quintuple the number of visitors to this blog which was not too low to start with.

Teach the controversy

Aaron Pierce who is now at faculty of University of Michigan wrote a nice and wise essay for Science:

• Teach the controversy (subscription required)

The title includes a witty analogy - I am apparently not the only one who thinks that this "controversy" about string theory and hypothetical alternatives is similar to the "controversy" about evolution and creationism. Both of these "controversies" are invented, promoted, and sometimes "taught" with a certain goal in mind and they don't reflect actual scientific results. See the Wikipedia page about the Teach the Controversy strategy to see that the two situations are essentially isomorphic.

Aaron is a phenomenologist - one of those who aren't hiding from others who spiritually live above a TeV, including the string theorists. ;-) His essay is technically a review of a blue book that all readers of The Reference Frame know and whose name will appear below. If you care why it's more relevant to review the blue book as opposed to the black book: it's because the blue book is sold better by a factor of five or so, among other reasons.

Much like Jim Cline, he starts with the difficult task of the unification of gravity with quantum field theory. Aaron explains that Green and Schwarz have made such a big impact because they showed the first theory that was not only capable to address this problem but that has also miraculously yet undoubtedly avoided some early complaints about it - namely the anomalies.



Figure 1: The Trouble With Shoes: a rise of a new technology, the fall of a foot, and what comes next

Aaron has an interesting idea that the author of the blue book is really complaining that it is no longer possible for the authors of seemingly fringe theories to get a lot of attention. The book is a lamentation for a bygone era, not an introduction to the field - because it is not too readable as an introduction for beginners.

The reason why it's no longer possible for fringe theories to get a lot of attention, Pierce explains, is simply that the bar has been raised. A new theory that would get a comparable attention would have to offer comparable results as string theory had, and no such theory is known at present.

Aaron Pierce answers the "bold claim" of the blue book that we live in an unprecedented breakdown of the marketplace of ideas in which a string-theoretical "conspiracy" has suppressed the diversity of ideas. Aaron writes that he has participated in many discussions that have revealed that the top-down theorists seem to have good and rational reasons to believe what they believe. Smolin didn't change this conclusion of Pierce: the marketplace of ideas is alive and well. Jim Cline and Barton Zwiebach came to the same conclusion.

I am afraid that the critics will argue that Aaron Pierce is a special agent of string theory from their conspiracy theories. :-)

Some of these critics often say that the difficulty of experimental testing is a characteristic feature of string theory. Aaron is a perfectionist so he offers not only a disagreement but also a full proof that it is not the case. Any theory of quantum gravity will have to face the same problem because of Wilson's insights about the Renormalization Group: all new effects predicted by any theory that can't be encoded into the shifts of the relevant and marginal couplings of the known low-energy effective theories are incredibly small.

In other words, as Aaron's colleague said, effective field theory allows you to make chicken soup without quantum gravity. ;-) Aaron cites Howard Georgi's 1993 article for the readers to comprehend the RG arguments.

Aaron explains that the recent insights have shown that the string-theoretical consistency places smaller constraints on low-energy physics than previously thought (or hoped). However,

1. it is premature to eliminate the possibility that such constraints will be found;
2. the relative ambiguity in the particle physics parameters is likely to be shared by any other hypothetical theory trying to address similar questions.

He concludes, much like Brian Greene, that despite these possible ambiguities, the questions of quantum gravity are still important and interesting. In fact, Lee Smolin agrees.

Aaron says that particle physics and mathematics owe a lot to string theory and many interesting questions could be asked about the progress in string theory. For example:

• How should science proceed if firm predictions don't appear for years?
• How do we evaluate progress if firm predictions don't exist?
• How much money should go to theories that are unlikely to be confirmed experimentally in our lifetime?
• How much credit should a field get for developing tools and results for other fields?

The Trouble with Physics only obliquely references these questions, Aaron says. It would be interesting to see them explored more fully. Meanwhile, theorists will continue to confront the thorny problem of quantum gravity with the most promising tool they can find. For the vast majority of them, this tool is string theory.

And that's Aaron's memo (and also mine, for that matter).

String theory and higher-dimensional real estate market

Most people think that the U.S. housing bubble has burst. Meanwhile, PRNewswire informs that

• Jonathon Keats
  

is an artist who is buying the rights to develop in half a dozen (or more) extra dimensions in California in general and San Francisco in particular for a few dollars.

Keats hopes to earn a lot of money. His strategy is a higher-dimensional version of Donald Trump's approach: Trump is buying the air in the third dimension above the buildings in California. Saul Perlmutter from Lawrence Berkeley Laboratory seems to supply the scientific insights that Keats needs in order to make a profit. See

• Yahoo / PRNewswire (news.google.com)
  

for more details. Well, I wish the Gentlemen a lot of good luck in their business. ;-)

"These frivolous affidavits"

Last Wednesday afternoon Robb Zipp and I met David and Rachel Van Os as they were completing a round of radio interviews at KPFT. Art Browning of Greenwatch decided to join us for the train trip in (since this was a Whistlestop Tour we thought it apropos to take the Metro light rail) and so we caravaned down to the Fannin South Park and Ride, met Richard Morrison and boarded the Preston Street Limited for the Old County Courthouse at 301 Franklin.

Richard and David fanned out to each end of the train and spoke to commuters all the way into downtown. At least a couple of hundred voters got to personally meet the next Attorney General of Texas and appeared thrilled at the prospect.

We met John Behrman and some of the early arrivals for the Whistlestop speech and then we all walked over to 201 Caroline and Beverly Kaufman's office so that David could file his affidavit. Robb and I were carrying so much gear that we chose not to run the gauntlet of security at the courthouse, including the airport-style metal detector and baggage screening.

Well, we missed one of the highlights of David's visit to the belly of the Texas Republican beast, because after he completed the paperwork and prepared to pay the fee, a clerk's office employee named Gregory Bousse' (this name is spelled phonetically and thus may not be accurate) indicated that the clerk would not be filing his affidavit, and further added the following editorial comment: "You people come around here every two years and file these frivolous affidavits ..." When David demanded to see the clerk, he was told she was not in the department, and a supervisory person named Ms. Contreras greeted him with the same caustic contempt. When he asked to speak to the person who had made the decision not to enter his affidavit into the public records of the county, Ms. Contreras indicated that it had been the county attorney who had done so. That of course was a lie, as the county attorney could not have been consulted on such a decision given the time frame, and in any event was not present to meet with David either.

So while 253 Texas counties will have these words on file as a public record, Harris County has chosen to deny them. How impressive is that?

About sixty supporters from Houston, Galveston, Wharton and even Angelina counties greeted David back at the old courthouse, and among the dignitaries were Judge Bill Moody and family, Melissa Taylor of the HCDP, and CD-02 challenger Gary Binderim and Stace Medellin. The humidity that day was stifling -- this must have been what kept the Chronicle away -- so we quickly adjourned to Chatters in the Heights and met about a hundred or so supporters, including Gerry Birnberg and Hank Gilbert and Jim Sharp and Mary Kay Green and Bill Connolly and Mark McDavid. As the evening grew late much of the group adjourned to one of the other fundraisers (James Pierre, Scott Hochberg, and Richard Garcia all had events going on).

I personally collapsed from exhaustion.

Robb and Stace have their accounts up with pictures, which you may have already read, since I'm a week late in posting this.

Electronic secretary

asks you not to play with your mouse in front of her face because it is so distracting!

Alain Connes et al.: predictions for masses

Ali H. Chamseddine, Alain Connes, and Matilde Marcolli argue in their paper

• Gravity and the standard model with neutrino mixing

that they can essentially predict the Higgs mass and the top quark mass. These interesting authors always attract attention. The reader is supposed to have seen a previous paper or a blog comment about it,

• Alain Connes: a theory of everything.

The new paper again shares the gauge coupling unification with GUT theories - which I think is still put in - but it also argues that they can relate the top quark mass to the W mass. More precisely, they argue on page 4 that at the unification scale,

• sum (3 generations) m_e^2 + m_nu^2 + 3 m_d^2 + 3 m_u^2 = 8 M_W^2.

I suppose that this is some tree-level formula although their treatment of the loop effects and renormalization is not transparent to me (partly because they argue that their model also has gravity in it). At any rate, this kind of a relation seems new to me - and my guess is that it will look new to all particle physicists and string theorists - and if it is not bogus, it would be really something. ;-)

Expert readers should try to decode the mathematically rich formalism and understand where their relation comes from.

The left-hand side is originally constructed from the squares of the Yukawa couplings. To have an idea what it means, realize that the left-hand side is dominated by 3 m_{top}^2, so you roughly get

• m_{top} = sqrt(8/3) M_W

which is marginally compatible with observations. After some arguments culminating on page 55, they also claim to predict the Higgs mass around 170 GeV. I am sure people should look at these statements in detail to see whether there is something materially new about them which would be fascinating.

Update: In 2008, Alain Connes became the most hapless scientist who ever tried to predict the Higgs mass. The CDF and D0 combined data at the Tevatron were able to falsify one particular possible value of the Higgs mass and it happened to be 170 GeV. See the article about this ironic story involving Connes. ;-)

If you're interested in skeptical results of a Harvard discussion:

1. It is not so difficult to predict reasonable values of the Higgs boson: All models that are well-defined at high energies inevitably lead to a Higgs mass in a reasonable window 115-170 GeV. If the mass were below 115 GeV (the same as the observational lower bound), the quartic coupling would run negative at some scale between a TeV and the GUT scale and destabilize the vacuum. On the other hand, if the mass were above 170 GeV, we would encounter a Landau pole below the GUT scale. The Connes et al. value is close to developing the Landau pole at high energies.
   
2. The relations between the masses of the fermions and W bosons can't hold generally at low energies because the equation is not invariant under the RG flow. If they mean something, they describe physics at high energies. But at high energies, one could probably construct many models that would lead to very different predictions - e.g. GUT with all the extra gauge bosons. With this viewpoint in mind, the prediction can't be viewed as a natural consequence of the simple low-energy limit but rather a randomly chosen extrapolation of it to high energies.
3. I was trying to conjecture that the relations of these kinds could hold at the string scale for masses in a broad class of models extracted from quantum gravity. This conjecture can be quickly falsified. In braneworlds and probably even in heterotic strings, one can obtain exponentially small Yukawa couplings as long as the Weyl fermions are localized at distinct brane intersections and/or different orbifold singularities so that the couplings are dominated by worldsheet instantons. On the other hand, the W boson masses are unsuppressed because they live in the "bulk" as opposed to intersections or singularities.
4. A general relation between the squares of the Yukawa couplings and the gauge couplings is not an unexpected feature because the models based on deconstruction typically generate the Yukawa couplings from the same parameters as the gauge couplings - from some higher-dimensional gauge couplings. But the spectrum of possibilities how to do that is probably large and Connes et al. just proposed one possibility from a large landscape of possibilities.

To summarize, I would bet that the derived relations are guesses that depend on so many arbitrary choices rather than a robust or unique theory that they can't quite be trusted. Also, I don't think that it is correct to describe this theory as a "unification" because it doesn't unify the forces. The different gauge forces still correspond to independent parts of the structure and the only sense in which they are unified with gravity is the terminology that calls the gauge bundles and corresponding Dirac's operators a "form of non-commutative geometry".

Superstring theory: the DNA of reality

Do you happen to be a reader who finds the popular accounts of theoretical physics in general and string theory in particular too shallow? Do you want something at a deeper level without learning the full mathematical machinery? Consider buying four DVDs with

• Sylvester James Gates, Jr.

I think that Prof. Gates is not only a famous researcher but also a very decent, wise, and charming expositor of science. The DVD will probably be a bit idiosyncratic and thought-provoking, too, which may be another reason for you to look at the DVDs. ;-)

Images from 254 Counties

I still owe a posting on Harris last Wednesday, but Snarko (David's webmistress) has been busy with the slideshows you see above and below, so I will let those do for now and deliver the tardy post later still.

Henry Tye: predictions of brane inflation

Henry Tye has written

• 29 pages

full of cosmic predictions of string theory, especially those of the brane inflation, one of the natural realizations of inflation within string theory. The distance between D3-branes and anti-D3-branes - an open string mode - plays the role of the inflaton scalar field. When the branes and antibranes collide, the inflation ends. This relates the inflationary scale with the string scale and is expected to be close to the GUT scale in these models.

Tye explains that the brane inflation is compatible with all existing observations and future, more accurate observations will be able to decide between various more detailed models. He also writes about the production and evolution of cosmic superstrings.

A related comment: Ottawa Citizen offers an article by

• Jim Cline: The big idea that won't die.

Jim Cline, an achieved cosmologist who describes himself as a former traditional skeptic in string theory, uses analogies from the car industry and the free markets (analogies that General Motors Inc. won't necessarily like) to explain that the recent criticism of string theory only underscores its success as a path to a unified description of nature.

Of course, he is not the first one to think about these market analogies. Besides your humble correspondent, this way of looking at things was also used by Prof. Barton Zwiebach who described various market corrections that have appeared in the past.




String theory has become the status quo, Cline explains. The rationally justified expectation that it is the most likely framework to explain the world at a deeper level has already been partially "priced in" - which always happens whenever partial information is available and before a complete evidence is given - and the underdogs will have to offer similarly impressive technical results that a former underdog called string theory did, if they want to attract the interest of researchers. Slandering is not good enough.

Hungarian uprising: 50 years

Today, it's been exactly half a century since the beginning of the

• Hungarian revolution in 1956,

the most important uprising in Hungary since the anti-Habsburg revolution of 1848. Decades later, October 23rd became the Hungarian national holiday. Congratulations to all Hungarian readers.

Much like other revolutions including the Czechoslovak Velvet Revolution in 1989, it was started by students. Students who loved freedom. Students who wanted the public radio to broadcast their demands - such as freedom and the removal of a Stalin's statue built on the place of a church ;-) - but who were instantly arrested, sparking a truly national movement.

A week later, the Soviet army stopped the uprising and killed 2,500 people or so while it lost 700 soldiers or secret policemen. 13,000 civilians were wounded and the moderate communist leader Imre Nagy was among the 350 citizens who were executed. About 200,000 Hungarians fled the country as refugees.

The action of the communists was so disgraceful that 700,000 out of 800,000 members of the Hungarian communist party canceled their membership within a month or so. That couldn't stop János Kádár, the newly installed leader, to gain a full control over the country. I suspect that this experience showing the Hungarians that communism can be really evil was one of the reasons why Hungary became an example of the moderate "goulash socialism" in the 1980s. Twenty years ago or so, we would visit Hungary that exhibited a sort of a mixed economic system. Mikhail Gorbachev became the first Soviet leader who apologized for the intervention.

From a strategic viewpoint, it was obvious that the communists - including the Soviet ones - had to suppress this uprising if they wanted their favorite regime to have a chance to survive in the long term. They had all the necessary requisites to do so. The message was also rather clear for the Czechoslovak reformers during the Prague Spring of 1968: it is useless to fight against the Soviet Union. Give it up. Well, I don't want to claim that the Czechoslovaks would fight if there had been no bloody experience with the Hungarian uprising but who knows. ;-)

The suppression of the Hungarian revolution has had many international consequences. The Time magazine declared the Hungarian freedom fighter to be the Man of 1956. More importantly, the Western European communist parties were divided. Most of their members and leaders considered the revolutionaries to be a reactionary mob: however not all of them.

Some people who love freedom will always be born. The defenders of communism and other totalitarian ideologies face a choice: either they allow freedom which means that they allow their favorite system to be marginalized and to evaporate, or they impose tough rules that eliminate all the people who actively prefer freedom over these rules. Most communists are able to solve elementary exercises in strategy which is why they choose the second option. Communism and every other extreme left-wing or extreme right-wing ideology that wants to mold the society according to a template is an unhuman monstrosity, and if it is not an unhuman monstrosity, it cannot be an extreme left-wing or extreme right-wing ideology with plans about the whole society.

The United Nations have passed a resolution that the intervention had violated the human rights of the Hungarian people and that was it. The United Nations were as useless in these important matters 50 years ago as they are useless today. Albert Camus wrote a letter protesting against the West's inaction but the power of a single Camus's letter has its limitations.

Today, we often want to complain that Iraq is a mess, and all these things. I still feel that these problems are less serious than the problems that the world had to swallow 50 years ago. Today, the Hungarian society seems sharply divided politically. Still, the divisions seem less bloody than the divisions that existed 50 years ago.

Despite the divisions, nearly everyone seems to agree: the freedom fighters in 1956 were heroes.

And that's the memo.

The temptation of rigor

Jacques Distler wrote a nice text about

• the role of rigor

in physics. He explains that rigor can't replace physical input and insights: very rigorous theorems may lead to very misleading physical conclusions. A reader could ask: how could a physicist ever question the unlimited power of a rigorous proof of a mathematical theorem? The technical answer is hidden in the assumptions of the theorem.

A proof of a theorem can be completely correct but the theorem can still be physically worthless. This occurs when the assumptions of the theorem are not satisfied by the relevant physical systems. When you start with incorrect or naive assumptions, your reasoning is likely to follow the GIGO rule: garbage in, garbage out. Rigor simply can't save you from errors in physical reasoning. There exists no systematic or rigorous method to find the correct physical theories.

Jacques mentions two examples:

1. algebraic holography
2. uniqueness of the polymer representation of the spatial diffeomorphism constraints

In both cases, rigorous proofs about systems called "quantum field theory" or "quantum gravity" have been constructed. These theorems are proven by valid proofs so what's the problem? The problem is that it is misleading to use the terms "quantum field theory" and "quantum gravity" for the theories addressed by these theorems.

In the case of algebraic holography, a rigorous proof due to Karl-Henning Rehren may be given to show that a local "quantum field theory in d+1-dimensional anti de Sitter space" is equivalent to a local "quantum field theory defined on its d-dimensional boundary". In this case, the definition of a "quantum field theory in d dimensions" is far too loose and includes structures that a physicist would never count as quantum field theories in d dimensions.

For example, a four-dimensional interacting Klein-Gordon theory can be included among three-dimensional quantum field theories according to this definition because the field "phi(x,y,z,t)" can be written as "phi_z(x,y,t)" with an index "z". There are many good reasons why continuous indices for fields are never treated as indices by the physicists and why the theoretical physicists would declare the conclusion of the theorem to be manifestly incorrect physically: local theories in d dimensions have free energy density that scales like "T^d" for high temperatures "T"; theories in different dimensions therefore can't be equivalent because you can always determine the dimension from the exponent.

However, with the unusual definitions of quantum field theories and their dimensionality used in the theorem, it is not surprising that one can prove a statement that sounds like Maldacena's correspondence. But in reality, it has nothing to do with the real essence of holography in quantum gravity. The theories discussed by algebraic holography are not holographic in any useful sense and they cannot be equivalent to lower-dimensional theories as long as you compute the spacetime dimension of a theory as the physicists do.

The second example - the polymer representations - is analogous but in some sense it suffers from the opposite flaw. In this case, the definition of "quantum gravity" is too narrow-minded. Too many things are assumed to be true about the structure that is called "quantum gravity": it is essentially assumed that quantum gravity must be constructed in the most naive way one can imagine.

These assumptions seem to be invalidated in the actual working theories of quantum gravity because of many unexpected twists and turns. For example, the definition of quantum gravity in terms of the dual CFT directly constructs the physical Hilbert space of quantum gravity - a superselection sector of string theory - without any intermediate steps where the diffeomorphism constraints would have to be imposed by hand. In this construction, a whole dimension of space - the holographic dimension - emerges unexpectedly: it was not used as a starting point at all. Still, all the facts that are normally derived as consequences of the diffeomorphism symmetry hold in this setup.

On the other hand, the polymer theorem is based on the assumption that neither of these "miracles" ever occurs. But these miracles and many other miracles that would be shocking for the thinkers in 2000 B.C. and other thinkers in the past have been found and they represent what we really mean by progress in science. The expectation that we already know all the right assumptions in physics is equivalent to the expectation that there will no longer be any substantial progress in the research of a given class of questions. This expectation is usually incorrect although it is valid whenever someone is smart and lucky enough to find the right assumptions.

The physical conclusion is obvious: Maldacena's correspondence is highly non-trivial, fascinating, and true - it is even more fascinating because rather reasonably sounding but naive and flawed arguments could lead us to believe, together with Roger Penrose, that it can't be right. And in some sense, quantum gravity and holography as painted by string theory is so valuable not only despite but because the structure is so rich that we can't yet fully squeeze these ideas into a small mobile rigorous box that is fully understood.

The fact that we don't yet know everything about string theory and its universal definition is actually one of the reasons why people can't resist and they continue to study it.

On the other hand, algebraic holography and polymer representations of quantum gravity are not so interesting because what is hiding in these fancy rigorous clothes is a physically flawed content that has nothing to do with the important principles of observable physics that are incorporated in the state-of-the-art theories. It's a content that has no relations with the actual surprises that we learned in the recent decades, centuries, and millenia. This content can perhaps be fully understood and the science behind it is falsifiable. Indeed, it is falsifiable in less than an hour. But it is a huge disadvantage, not an advantage, of such a system of ideas.

Rigor can sometimes be useful for physics, especially when physicists are making an error that is caused by a somewhat sloppy reasoning. But the physicists typically reach the right conclusions without insisting on all the formal features of a rigorous proof: they prefer the content over the form. If someone prefers the form over content, it doesn't save him or her from deep physical errors or from naivite. That's why we have so many examples of pairs of answers among which the more rigorous one is obviously the wrong one physically.

The previous articles related to the relation of rigor and physics:

• Category theory and physics
• Bert Schroer's paper
• Algebraic quantum field theory
• Platonic world of mathematical ideas
• Defense of the path integrals
• Physics and mathematics: boundaries and interactions
• Roger Penrose and holography