Saturday, December 31, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Testing E=mc2 for centuries

Chad Orzel seems to disagree with my comments about the interplay between the theory and experiment in physics. That's too bad because I am convinced that a person who has at least a rudimentary knowledge about the meaning, the purpose, and the inner workings of physics should not find anything controversial in my text at all.

Orzel's text is titled "Why I could never be a string theorist" but it could also be named "Why I could never be a theorist or something else that requires to use the brain for extended periods of time". Note that the apparently controversial theory won't be string theory; it will be special relativity. The critics who can't swallow string theory always have other, much older and well-established theories that they can't swallow either.

The previous text about the theory vs. experiment relations

Recall that I was explaining a trivial fact that in science in general and physics in particular, we can predict the results of zillions of experiments without actually doing them. It's because we know general enough theories - that have been found by combining the results of the experiments in the past with a great deal of theoretical reasoning - and we know their range of validity and their accuracy. And a doable experiment of a particular kind usually fits into a class of experiments whose results are trivially known and included in these theories. This is what we mean by saying that these are the correct theories for a given class of phenomena. An experiment with a generic design is extremely unlikely to be able to push the boundaries of our knowledge.

When we want to find completely new effects in various fields, we must be either pretty smart (and lucky) or we must have very powerful apparata. For example, in high-energy physics, it's necessary that we either construct accelerators that accelerate particles to high energies above 100 GeV or so - this is why we call the field high-energy physics - or we must look for some very weak new forces, for example modifications of gravity at submillimeter experiments, or new, very weakly interacting particles. (Or some new subtle observations in our telescopes.)

If someone found a different, cheaper way to reveal new physics, that would be incredible; but it would be completely foolish to expect new physics to be discovered in a generic cheap experiment.

Random experiments don't teach us anything

It's all but guaranteed that if we construct a new low-energy experiment with the same particles that have been observed in thousands of other experiments and described by shockingly successful theories, we are extremely unlikely to learn anything new. This is wasting of taxpayers' money especially if the experiments are very expensive.

In the particular case of the recent "E=mc^2 tests", the accuracy was "10^{-7}" while we know experimentally that the relativistic relations are accurate with the accuracy "10^{-10}", see Alan Kostelecky's website for more concrete details. We just know that we can't observe new physics by this experiment.

Good vs. less good experiments

In other fields of experimental physics, there are other rules - but it is still true that one must design a smart enough experiment to be able to see something new or to be able to measure various things (or confirm the known physical laws) with a better accuracy than the previous physicists. There are good experimentalists and less-good experimentalists (and interesting and not-so-interesting experiments) which is the basic hidden observation of mine that apparently drives Ms. or Mr. Orzel up the wall.

Once again: What I am saying here is not just a theorist's attitude. Of course that it is also the attitude of all good experimentalists. It is very important for an experimentalist to choose the right doable experiments where something interesting and/or new may be discovered (or invented) with a nonzero probabilitity. There is still a very large difference between the experiments that reveal interesting results or inspire new ideas and experiments that no one else finds interesting.

Every good experimentalist would subscribe to the main thesis that experiments may be more or less useful, believe me. Then there are experimentalists without adjectives who want to be worshipped just for being experimentalists and who disagree with my comments; you may guess what is the reason.

Of course that one may design hundreds of experiments that are just stamp-collecting - or solving a homework problem for your experimental course. I am extremely far from thinking that this is the case everywhere outside high-energy physics. There have been hundreds of absolutely fabulous experiments done in all branches of physics and dozens of such experiments are performed every week. But there have also been thousands of rather useless experiments done in all these fields. Too bad if Ms. or Mr. Orzel finds it irritating - but it is definitely not true that all experiments are created equal.

Interpreting the results

Another issue is that if something unexpected occured in the experiment that was "testing E=mc^2", the interpretation would have to be completely different than the statement that "E=mc^2" has been falsified. It is a crackpot idea to imagine that one invents something - or does an experiment with an iron nucleus or a bowl of soup - that will show that Einstein was stupid and his very basic principles and insights are completely wrong.

Hypothetical deviations from the Lorentz invariance are described by terms in our effective theories. Every good experimentalist first tries to figure out which of them she really measures. Neither of these potential deviations deserves the name "modification of the mass-energy relation" because even the Lorentz-breaking theories respect the fact that since 1905, we know that there only exists one conserved quantity to talk about - mass/energy - that can have various forms. We will never return to the previous situation in which the mass and energy were thought to be independent. It's just not possible. We know that one can transform energy into particles and vice versa. We can never unlearn this insight.

New physics vs. crackpots' battles against Einstein

Einstein was not so stupid and the principles of his theories have been well-tested. (The two parts of the previous sentence are not equivalent but they are positively correlated.) To go beyond Einstein means to know where is the room for any improvement, clarification, or deformation of his theories and for new physics, and the room is simply not in the space of ideas that "E=mc^2 is wrong" or "relativity is flawed". A good experimentalist must know something about the theory, to avoid testing his own laymen's preconceptions about physics that have nothing to do with the currently open questions in physics.

Whether or not an experimental physicist likes it or not, we know certain facts about the possible and impossible extensions and variations of the current theories - and a new law that "E=mc^2" will be suddenly violated by one part in ten million in a specific experiment with a nucleus is simply not the kind of modification that can be done with the physical laws as we know them. Anyone who has learned the current status of physics knows that this is not how serious 21st century physics looks like. The current science is not about disproving some dogmatic interpretations of Bohr's complementarity principle either.

Chad Orzel is not the only one who completely misunderstands these basic facts. Hektor Bim writes:

  • Yeah, this post from Lubos blew me away, and I’ve been trained as a theorist.

Well, it does not look like a too well-trained one.

  • As long as we are still doing physics (and not mathematics), experiment rules.

Experiments may rule, but there are still reasonable (and even exciting) experiments and useless (and even stupid) experiments. If someone thinks that the "leading role" of the experiments means that the experimentalists' often incoherent ideas about physics are gonna replace the existing theories of physics and that every experiment will be applauded even if it is silly, is profoundly confused. Weak ideas will remain weak ideas regardless of the "leading role" of the experiments.

  • What also blew me away is that Lubos said that “There is just no way how we could design a theory in which the results will be different.” This is frankly incredible. There are an infinite number of ways that we could design the theory to take into account that the results would be different.

Once again, there are no ways how to design a scientific theory that agrees with the other known experiments but that would predict a different result of this particular experiment. If you have a theory that agrees with the experiments in the accelerators but gives completely new physics for the iron nucleus, you may try to publish it - but don't be surprised if you're described as a cook.

Of course that crackpots always see millions - and the most spectacular among them infinitely many ;-) - ways to construct their theories. The more ignorant they are about the workings of Nature, the more ways to construct the theories of the real world they see. The most sane ones only think that it is easy to construct a quantum theory of gravity using the first idea that comes to your mind; the least sane ones work on their perpetuum mobile machines.

I only mentioned those whose irrationality may be found on the real axis. If we also included the cardinal numbers as a possible value of irrationality, a discussion of postmodern lit crits would be necessary.

Scientific theories vs. crackpots' fantasies

Of course someone could construct a "theory" in which relativity including "E=mc^2" is broken whenever the iron nuclei are observed in the state of Massachusetts - much like we can construct a "theory" in which the law of gravity is revoked whenever Jesus Christ is walking on the ocean. But these are not scientific theories. They're unjustifiable stupidities.

The interaction between the theory and experiments goes in both ways

It is extremely important for an experimental physicist to have a general education as well as feedback from the theorists to choose the right (and nontrivial) things to measure and to know what to expect. It is exactly as important as it is for a theorist to know the results of the relevant experiments.

Another anonymous poster writes:

  • What Lumo seems to argue is that somehow we can figure out world just by thinking about it. This is an extremely arrogant and short-sighted point of view, IMPO – and is precisely what got early 20th century philosophers in trouble.

What I argue is that it is completely necessary for us to be thinking about the world when we construct our explanations of the real world as well as whenever we design our experiments. And thinking itself is responsible at least for one half of the big breakthroughs in the history of science. For example, Einstein had deduced both special relativity as well as general relativity more or less by pure thought, using only very general and rudimentary features of Nature known partially from the experiments - but much more deeply and reliably from the previous theories themselves. (We will discuss Einstein below.)

Thinking is what the life of a theoretical physicist is mostly about - and this fact holds not only for theoretical physicists but also other professions including many seemingly non-theoretical ones. If an undereducated person finds this fact about the real world "arrogant", it is his personal psychological problem that does not change the fact that thinking and logical consistency are among the values that matter most whenever physical theories of the real world are deduced and constructed.

The anonymous poster continues:

  • By the same reasoning the orbits of the planets must be circular – which is what early “philosophers” argued at some point.

Circular orbits were an extremely useful approximation to start to develop astrophysics. We have gone through many other approximations and improvements, and we have also learned how to figure out which approximations may be modified and which cannot. Cutting-edge physics today studies neither circular orbits nor the questions whether "E=mc^2" is wrong; it studies very different questions because we know the answers to the questions I mentioned.

Pure thought in the past and present

A wise physicist in 2005 respects the early scientists and philosophers for what they have done in the cultural context that was less scientifically clear than the present era, but she clearly realizes their limitations and knows much more than those early philosophers. On the other hand, a bad and arrogant scientist in 2005 humiliates the heroes of the ancient science although he is much more dumb than they were, and he is asking much more stupid questions and promoting a much more rationally unjustifiable criticism of science in general than the comparably naive early philosophers could have dreamed about.

Of course that in principle, one can get extremely far by pure thought, if the thought is logically coherent and based on the right principles, and many great people in the history of science indeed had gotten very far. These are the guys whom we try to follow, and the fact that there have been people who got nowhere by thinking cannot change the general strategy either.

  • Anthropic principle completely destroys whatever is left of the “elegance” argument, which is why it’s entertaining to see what will happen next.

I know that some anti-scientific activists would like to destroy not only the "elegance" of science but the whole science - and join forces with the anthropic principle or anything else if necessary - but that does not yet mean that their struggle has any chance to succeed or that we should dedicate them more than this single paragraph.

Another anonymous user writes:

  • As far as what Lubos meant, only he can answer that. But it would be obviously foolish to claim relativity could have been deduced without experimental input, and Lubos, whatever else he might be, is no fool.

History of relativity as a victory of pure thought

If interpreted properly, it would not be foolish; it is a historical fact. For example, I recommend you The Elegant Universe by Brian Greene, Chapter 2, for a basic description of the situation. Einstein only needed a very elementary input from the experiments - namely the invariance of physical laws under uniform motion; and the constancy of speed of light - which naturally follows from Maxwell's equations and Einstein was sure that the constancy was right long before the experiments showed that the aether wind did not exist.

It is known pretty well that the Michelson-Morley experiments played a rather small role for Einstein, and for some time, it was even disputed whether Einstein knew these experiments at all back in 1905. (Yes, he did.) Some historians argue that the patented ideas about the train synchronization themselves played a more crucial role. I don't believe this either - but the small influence of the aether wind experiments on Einstein's thinking seems to be a consensus of the historians of science.

Einstein had deeply theoretical reasons to be convinced about both of these two assumptions. Symmetry such as the Galilean/Lorentz symmetry or "the unity of physical explanations" are not just about some irrelevant or subjective concepts of "beauty". They are criteria that a good physicist knows how to use when he or she looks for better theories. The observation that the world is based on more concise and unified principles than what the crackpots and laymen would generally expect is an experimentally verified fact.

These two observations are called the postulates of special relativity, and the whole structure of special relativity with all of its far-reaching consequences such as the equivalence of matter and energy follows logically. Needless to say, all of these effects have always been confirmed - with accuracy that currently exceeds the accuracy available to the experimentalists of Einstein's era by very many orders of magnitude. Special relativity is a genuine and true constraint on any theory describing non-gravitational phenomena in our Universe, and it is a strong constraint, indeed.

Importance of relativity

Whoever thinks that it is not too important and a new experiment with a low-energy nucleus may easily show that these principles are wrong, which essentially allows us to ignore special relativity, and that everything goes after all, is a crackpot.

General relativity: even purer thought

In a similar way, the whole structure of general relativity was derived by the same Einstein purely by knowing the previous special theory of relativity plus Newton's approximate law of gravity, including the equivalence of the inertial and gravitational mass; the latter laws were 250 years old. There was essentially no room for experiments. The first experiments came years after GR was finished, and they always confirmed Einstein's predictions.

The known precession of Mercury's perihelion is an exception; this prediction of GR was known before Einstein, but Einstein only calculated the precession after he had completed his GR, and henceforth, the precession could not directly influence his construction of GR. He was much more influenced and impressed by Ernst Mach, an Austrian philosopher. I don't intend to promote Mach - but my point definitely is to show that the contemporary experiments played a very small role when both theories of relativity were being developed.

There were also some experiments that argued that they rejected the theory, and Einstein knew that these experiments had to be wrong because "God was subtle but not malicious". Of course that Einstein was right and the experiments were wrong. (Similar stories happened to many great theoretical physicists; an experiment of renowned experimentalists that claimed to have falsified Feynman-Gell-Mann's theory of V-A interactions was another example - and Feynman knew right away when he was reading the paper that the experimentalists were just being silly.) Our certainty today that special relativity (or the V-A nature of the weak interactions) is correct in the "simply doable" experiments is much higher than our confidence in any single particular experimentalist. You may be sad or irritated, but that's about everything that you can do against this fact.

Other theories needed more experiments

It would be much harder to get that far without experiments in quantum mechanics and particle physics, among many other branches of physics and science, but whoever questions the fact that there are extremely important insights and principles that have been found - and/or could be found or can be found - by "pure thought" (or that were correctly predicted long before they were observed), is simply missing some basic knowledge about science.

Although I happily admit that we could not have gotten that far without many skillful (and lucky) experimentalists and their experiments, there have been many other examples beyond relativity in which important theories and frameworks were developed by pure mathematical thinking whose details were independent of experiments. The list includes, among hundreds of other examples,

  • Dirac's equation. Dirac had to reconcile the first-order Schrödinger equation with special relativity. As a by-product, he also predicted something completely unknown to the experimentalists, namely antiparticles. Every successful prediction may be counted as an example of theoretical work that was not driven by experiments.
  • Feynman's diagrams and path integral. No one ever really observed "diagrams" or "multiple trajectories simultaneously contributing to an experiment". Feynman appreciated Dirac's theoretical argument that the classical concept of the action (and the Lagrangian) should play a role in quantum mechanics, too, and he logically deduced that it must play role because of his sum over trajectories. The whole Feynman diagram calculus for QED (generalizable to all other QFTs) followed by pure thought. Today we often say that an experiment "observes" a Feynman diagram but you should not forget about the huge amount of pure thought that was necessary for such a sentence to make any sense.
  • Supersymmetry and string theory. I won't provoke the readers with a description.

Lorentz violations are not too interesting and they probably don't exist

  • If he is claiming that Lorentz invariance must be exact at all scales, then I agree that he’s being ridiculous. But I think it is reasonable to claim that this experiment was not really testing Lorentz invariance at a level where it has not been tested before.

What I am saying is that it is a misguided approach to science to think that the next big goal of physics is to find deviations from the Lorentz invariance. We won't find any deviations. Most likely, there aren't any. The hypotheses about them are not too interesting. They are not justified. They don't solve any puzzles. Even if we find the deviations and write down the corresponding corrections to our actions, we will probably not be able to deduce any deep idea from these effects. Since 1905 (or maybe the 17th century), we know that the Lorentz symmetry is as fundamental, important and natural as the rotational symmetry.

The Lorentz violation is just one of many hypothetical phenomenological possibilities that can in principle be observed, but that will probably never be observed. I find it entertaining that those folks criticize me for underestimating the value of the experiments when I declare that the Lorentz symmetry is a fundamental property of the Universe that holds whenever the space is sufficiently flat. Why is it entertaining? Because my statement is supported by millions of accurate experiments while their speculation is supported by 0.0001 of a sh*t. It looks like someone is counting negative experiments as evidence that more such experiments are needed.

The only reason why the Lorentz symmetry irritates so many more people than the rotational symmetry is that these people misunderstand 20th century physics. From a more enlightened perspective, the search for the Lorentz breaking is equally (un)justified as a search for the violation of the rotational symmetry. The latter has virtually no support because people find the rotational symmetry "natural" - but this difference between rotations and boosts is completely irrational as we have known since 1905.

Parameterizing Lorentz violation

In the context of gravity, the deviations from the Lorentz symmetry that can exist can be described as spontaneous symmetry breaking, and they always include considering the effect of gravity as in general relativity and/or the presence of matter in the background. In the non-gravitational context, these violations may be described by various effective Lorentz-breaking terms, and all of their coefficients are known to be zero with a high and ever growing degree of accuracy. Look at the papers by Glashow and Coleman, among others.

Undoing science?

The idea that we should "undo" the Lorentz invariance, "undo" the energy-mass equivalence, or anything like that is simply an idea to return physics 100 years into the past. It is crackpotism - and a physics counterpart of creationism. The experiments that could have been interesting in 1905 are usually no longer so interesting in 2005 because many questions have been settled and many formerly "natural" and "plausible" modifications are no longer "natural" or "plausible". The previous sentence comparing 1905 and 2005 would be obvious to everyone if it were about computer science - but in the case of physics, it is not obvious to many people simply because physics is harder to understand for the general public.

But believe me, even physics has evolved since 1905, and we are solving different questions. The most interesting developments as of 2005 (for readers outside the Americas: 2006) are focusing on significantly different issues, and whoever describes low-energy experiments designed to find "10^{-7}" deviations from "E=mc^2" as one of the hottest questions in 2005 is either a liar or an ignorant. It is very fine if someone is doing technologically cute experiments; but their meaning and importance should not be misinterpreted.

Internet gender gap

First, an off-topic answer. Celal asks me about the leap seconds - why has not the Earth already stopped to rotate if there are so many leap seconds. The answer is that we are now indeed inserting a leap second in most of the years - which means that one year is longer by roughly 1 second than it was back in 1820 when the second was defined accurately enough. More precisely, what I want to say is that one solar day is now longer by roughly 1/365 of a second than it was in the 19th century; what matters is of course that the noon stays at 12 pm.

Although the process of slowing down the Earth's rotation has some irregularities, you can see that you need roughly 200 years to increase the number of the required leap seconds per year by one. In order to halve the angular velocity, you need to increase the number of leap seconds roughly by 30 million (the number of seconds per year), which means that you need 30 million times 200 years which is about 6 billion years. Indeed, at time scales comparable to the lifetime of the solar system, the length of the day may change by as much as 100 percent.

100 percent is a bit of exaggeration because a part of the recent slowing is due to natural periodic fluctuations and aperiodic noise, not a trend. However, coral reefs indeed seem to suggest that there were about 400 days per year 0.4 billion years ago. Don't forget that the slowing down is exponential, I think, and therefore the angular velocity will never quite drop to zero (which has almost happened to our Moon).

BBC informs that

While the same percentage of men and women use the internet, they use it in very different ways & they search for very different things. Women focus on maintaining human contacts by e-mail etc. while men look for new technologies and ways to do new things in novel ways.

  • "This moment in internet history will be gone in a blink," said Deborah Fallows, senior research fellow at Pew who wrote the report.

I just can't believe that someone who is doing similar research is simultaneously able to share such feminist misconceptions. The Internet has been around for ten years and there has never been any political or legal pressure for the men and women to do different things - the kind of pressures in the past that is often used to justify similar hypotheses about the social origin of various effects.

Friday, December 30, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Next target of terrorists: Indian string theorists

A newspaper in Bombay informs that

The terror attack at the Indian Institute of Science campus in Bangalore on Wednesday that killed a retired IIT professor has sent shockwaves through the Indian blogosphere.

Blogger and researcher, Kate, wondered if Tata Institute of Fundamental Research [the prominent Indian center of string theory] would be the next target.

...

Rashmi Bansal expressed sadness at scientists becoming the latest terror victims. “I mean, sure, there would be some routine security checks at the gate, but who seriously believes that a bunch of scientists gathered to discuss string theory or particle physics could be of interest to the Lashkar-e-Toiba?” she wrote in her blog, Youth Curry (http://youthcurry.blogspot.com/).

Ms. Bansal may change her mind if she analyzed some posters here - to see at least a "demo" how the anger against the values of modern science can look like. More generally, I emphasize that my warning is absolutely serious. It is not a joke, and I've erased a misleading anonymous comment that suggested that.

Finally, I think that whoever thinks that a scientist cannot become a victim of terrorists is plain stupid. The islamic extremists fight against the whole modern civilization, and the string theorists in India and elsewhere - much like the information technologies experts - are textbook examples of the infiltration of the modern civilization and, indeed, the influence of the Western values - or at least something that was associated with the Western values at least for 500 years.

Everyone who observes the situation and who is able to think must know that Bangalore has been on the terrorists' hit list for quite a while.

If the person who signed as "Indian physicist" does not realize that and if he or she were hoping that the terrorists would treat him or her as a friend (probably because they have the same opinions about George W. Bush?), I recommend him or her to change the field because the hopes were completely absurd.

I give my deepest condolences to the victim's family but I am not gonna dedicate special sorrow to the victim, Prof. Puri, just because he was a retired professor. There are many other innocent people being killed by the terrorists and I am equally sad for all of them. The death of the innocent people associated with "our" society is of course the main reason why I support the war on terror - or at least its general principles. The attack against the conference is bad, but for me it is no surprise. And the casualties of 9/11 were 3,000 times higher which should still have a certain impact on the scale of our reactions.

Third string revolution predicted for physics

CapitalistImperialistPig has predicted

for 2006, started by someone who is quite unexpected. It would be even better if the revolution appeared in the first paper of the year.

Sidney Coleman Open Source Project

Update: See the arXiv version of Sidney Coleman's QFT notes (click)
Jason Douglas Brown has been thinking about a project to transcribe the QFT notes of a great teacher into a usable open source book. I am going to use the notes in my course QFT I in Fall 2006; see the Course-notes directory.

We are talking about 500 pages and about 10 people who would share the job. If you want to tell Jason that it is a bad or good idea, or join his team, send an e-mail to
  • jdbrown371 at hisurfer.net

Bayesian probability I

See also a positive article about Bayesian inference...
Two days ago, we had interesting discussions about "physical" situations where even the probabilities are unknown.

Reliable quantitative values of probabilities can only be measured by the same experiment repeated many times. The measured probability is then "n/N" where "n" counts the "successful measurements" among all experiments of a certain kind whose total number is "N". This approach defines the "frequentist probability", and whenever we know the correct physical laws, we may also predict these probabilities. If you know the "mechanism" of any system in nature - which includes well-defined and calculable probabilities for all well-defined questions - you can always treat the system rationally.

Unknown probabilities

It is much more difficult when you are making bets about some events whose exact probabilities are unknown. Even in these cases, we often like to say a number that expresses our beliefs quantitatively. Such a notion of probability is called Bayesian probability and it does not really belong to exact sciences.

Thursday, December 29, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

All stem cell lines were fabricated

All - not just nine - of Hwang Woo-Suk's eleven stem cell lines were fabricated, a panel of Seoul National University concluded today.

It is still plausible that Hwang's team has successfully cloned a human embryo and the Afghan hound. And Hwang still claims to have developed a technology to build the stem cell lines although he is no longer a trustworthy source. However, the apparent failure to have actually produced the patient-specific stem cell lines implies that a realistic application of these biotechnologies in medicine may be decades (or infinitely far) away.

Moreover, the Washington Post claims that the Korean government has probably bribed some scientists - potential whistleblowers - in order to protect the non-existent good name of Korean biology in the international context.

Some people argue that the whole science will suffer as a consequence of this scandal. I don't buy these worries. If someone criticizes the work of the Korean scientists; as well as the work of their colleagues everywhere in the world who could not figure out what was going on; as well as the work of the journalists who inflated this research into a sensation; as well as the editors of the journals and the Korean government officials who have paid a lot of money without proper checks and balances - I am convinced that at least 90% of this criticism is justified.

Wednesday, December 28, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Wikipedia

Comment about the new colors: I believe that the new colors are not a registered trademark of Paul Ginsparg. Moreover, mine are better.

Just a short comment about this creation of Jimbo Wales et al. I am impressed how unexpectedly efficient Wikipedia is. Virtually all of its entries can be edited by anyone in the world, even without any kind of registration. When you realize that there are billions of not-so-smart people and hundreds of millions of active idiots living on this blue planet - and many of them have an internet access - it is remarkable that Wikipedia's quality matches that of Britannica.

But this kind of hypertext source of knowledge is exactly what the web was originally invented for.

Moreover I am sure that Wikipedia covers many fields much more thoroughly than Britannica - and theoretical physics may be just another example. Start with list of string theory topics, 2000+ of my contributions, or any other starting point you like. Try to look for the Landau pole, topological string theory, heterotic string, or thousands of other articles that volunteers helped to create and improve. Are you unsatisfied with some of these pages? You can always edit them.

Tuesday, December 27, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Hubble: cosmic string verdict by February

Let me remind you that the Hubble pictures of the cosmic-string-lensing CSL-1 candidate, taken by Craig Hogan et al., should be available by February 2006. Ohio's Free Times interviews Tanmay Vachaspati who has studied cosmic strings for 20 years. (Via Rich Murray.)

Monday, December 26, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Evolution and the genome

The editors of the Science magazine have chosen the evolution - more precisely, the direct observations of evolution through the genome - to be the scientific breakthrough of 2005.

I think it is a fair choice. The analyses of the genome are likely to become a massive part of "normal science" with a lot of people working on it and a lot of successes and potential applications for the years to come. I expect many discoveries in this direction to shed light on the past lifeforms; on the explicit relationships between the currently existing species and their common ancestry; the evolutionary strategies of diseases and our strategies to fight them; and finally on the new possible improvements of the organisms that are important for our lives, and - perhaps - the human race itself.

Stem cell fraud

Incidentally, the breakthrough of the year 2005 for the U.S. particle physics is called "Particle physicists in the U.S. would like to forget about 2005" which may be fair, too. However, the situation is still better than in stem cell research where some of the seemingly most impressive results in the past years - those by Hwang Woo Suk from Korea - have been identified as an undisputable fraud. Steve McIntyre points out that Hwang was one of Scientific American's 50 visionaries together with Michael Mann who, after a comparable incident (one involving the "hockey stick graph"), was not fired but instead promoted. Steve McIntyre has also written the world's most complete chronology of the scandal. Google tells you more about the sad story of scientific consensus behind the former Korean national hero. It's amazing how this fraud that no one could apparently reproduce immediately gained 117 citations. Should we believe the Koreans - without testing them - because they are so skillful in manipulating the chopsticks? Or perhaps because it is nice to see that the U.S. science is falling behind - "certainly" because of George W. Bush? Have the people in that field lost their mind? Or is it really the case that the whole cloning field - or perhaps even all Bush critics in the world - are participating in a deliberate international fraud?

Back to the positive story: the genetic evidence for evolution.

New tools make questions solvable

New scientific methods and technologies often have the capacity to transform an academic dispute whose character used to be almost religious into an obvious set of facts. Let me give you two examples.

The death of hidden variables

The first example are Bell's inequalities. Before they were found, it was thought that no one could ever determine whether the quantum mechanical "randomness" was just an emergent process based on some classical "hidden variables"; this debate was thought to be a philosophical one forever. After the inequalities were found and the experimental tests confirmed quantum mechanics, it became clear that the quantum mechanical "randomness" is inherent. It cannot be emergent - unless we would be ready to accept that the underlying hidden variables obey non-local (and probably non-relativistic) classical laws of physics which seems extremely unlikely.

Sun's chemistry and spectroscopy

My second example goes back to the 19th century. Recall that the philosopher Auguste Comte, the founder of positivism, remarked in his "Course de philosophie positive" that the chemical composition of the Sun would forever remain a mystery.

It only took seven years or so, until 1857, to show that Comte was completely wrong. Spectroscopy was discovered and it allowed us to learn the concentration of various elements in the Sun quite accurately. Unfortunately, this discovery came two years after Comte's death and therefore he could not see it. Incidentally, two more years later, in 1859, Darwin published his theory.

The last we-will-never-know people

Many people have been saying similar things about physics in general: physics could never determine or explain UV or XY - and all of these people have already been proved wrong except for those who argue that the parameters of the Standard Model can't be calculated with a better accuracy than what we can measure; the latter group will hopefully be proved wrong in our lifetime.

Speed of evolution

What do the new discoveries tell us about the evolution? First of all, evolution is not fuzzy. It is "quantized", if you allow me to use physics jargon, and the evolutionary changes are directly encoded in the genes that can be equally easily decoded.

A related and equally important observation is that the evolutionary changes are quite abrupt. We have never observed skeletons of bats with one wing and similar creatures - as the creationists (including those in a cheap tuxedo, using the words of pandas from level 2) have been quite correctly pointing out for decades. Indeed, it often takes a single mutation only to establish a new species.

Many mutations are harmful and they become immediately a subject of natural selection. Some mutations allow the organisms to survive. All these changes were making the tree of life ramify all diversify - and they are still doing so although this process is nowadays slower than some other types of developments.

Reply to Pat Buchanan

Let me finally choose an article from Dembski's blog in which he reposts

It is entertaining to see a text whose political part is more or less true but the scientific one is so clearly and completely wrong. Let's clarify some errors of Buchanan's:

  • In his “Politically Correct Guide to Science,” Tom Bethell ...

Surprisingly, the book is called "Politically Incorrect...", not "Politically correct...". Tom Bethell is rather unlikely to be politically correct.

  • For generations, scientists have searched for the “missing link” between ape and man. But not only is that link still missing, no links between species have been found.

Because there are no highly refined intermediate links of the type Buchanan suggests; one mutation often makes these changes occur and the evolution is far from being a smooth, gradual, and continuous process. However, chimps' genome has been decoded. We can not only see that chimpanzees are our closest relatives but also deduce the existence of a common ancestor. Our relationship with the chimps is no longer a matter of superficial similarity; a long sequence of bits - a microscopic genetic information - reveals a much more detailed picture.

  • As Bethell writes, bats are the only mammals to have mastered powered flight. But even the earliest bats found in the fossil record have complex wings and built-in sonar. Where are the “half-bats” with no sonar or unworkable wings?

Half-bats with unworkable wings are predicted by Darwin to die quite rapidly, so there should not be too many fossils around. Observations seem to confirm this prediction of Darwin's theory, too. Indeed, such changes must proceed quickly and today we know that a single change of the genome is capable to induce these macroscopic changes.

  • Their absence does not prove — but does suggest — that they do not exist. Is it not time, after 150 years, that the Darwinists started to deliver and ceased to be taken on faith?

Don't tell me that you don't think that this comment of Pat Buchanan sounds just like Peter Woit. ;-) Let me remark, in both cases, that 150 years and maybe even 30 years is probably a long enough time to start to think about the possibility that the "alternatives" to evolution or string theory can't ever work.

  • No one denies “micro-evolution” — i.e., species adapting to their environment. It is macro-evolution that is in trouble.

First of all, it is not a trouble - it was chosen to be the most spectacularly confirmed scientific paradigm by discoveries done in 2005. Second of all, the difference between "micro-evolution" and "macro-evolution" is just a quantitative one. Most of the errors that Buchanan and other creationists do can be blamed on this particular error in their thinking: they incorrectly believe that objects in the world can be dogmatically and sharply divided to alive and not alive; intelligent and not intelligent; micro-evolution and macro-evolution. (And of course, someone would also like to divide the whole human population to believers and non-believers.)

Neither of these categories can be quite sharply defined. Even though the species are defined by "discrete", "quantized" bits of information encoded in the genome, it does not mean that each species can be classified according to some old, human-invented adjectives. Science does not break down but the adjectives used in the unscientific debate - or the Bible - certainly do break down when we want to understand life (or the whole Universe, for that matter) at a deeper level.

The world is full of objects whose "aliveness" is disputable - such as the viruses. The same world also offers evolutionary steps that can be safely classified neither as micro-evolution nor as macro-evolution. Finally, there are many organisms in the world that are only marginally intelligent, and I am afraid that this group would include not only chimps but maybe also some syndicated columnists. ;-)

  • The Darwinian thesis of “survival of the fittest” turns out to be nothing but a tautology. How do we know existing species were the fittest? Because they survived. Why did they survive? Because they were the fittest.

I completely agree that the operational definition of the "fittest" is circular. It is the whole point of Darwin's notion of natural selection that "being the fittest" and "have a higher chance to survive" are equivalent. However, there is also a theoretical way to derive whether an animal is "the fittest" which can be used to predict its chances to survive. Such a derivation must, however, use the laws of nature in a very general sense - because it is the laws of nature that determine the chances to survive. Sometimes it is easy to go through the reasoning. A bird without legs in between the tigers does not have a bright future. Sometimes the conclusion is much harder to make. But the main message is that these questions can be studied scientifically and the answers have definitely influenced the composition of the species on our planet.

  • While clever, this tells us zip about why we have tigers.

"Why we have tigers?" is not a scientifically meaningful question unless a usable definition of a tiger is added to it as an appendix. The Bible can answer such verbal, non-scientific question, by including the word "tiger" in one of the verses (and by prohibiting everyone to ask where the word and the properties of the animal came from). Science can only answer meaningful questions. For example, we may try to answer the question why the hairy mammals - beasts of prey - whose maximum speed exceeds 50 mph have evolved.

  • It is less a scientific theory than a notion masquerading as a fact.

It is somewhat entertaining that the word "notion" is apparently supposed to have a negative meaning. Notions, concepts, and ideas are an essential part of our theories - and the word "theory" is not negative either because the best and most reliable things we know about the real world are theories based on notions and ideas.

  • For those seeking the source of Darwin’s “discovery,” there is an interesting coincidence.

Those who judge the validity of a scientific theory according to the coincidences that accompanied its original discovery are intellectual equivalents of chimpanzees, and therefore they are another piece of evidence for evolutionary biology.

  • As Bertrand Russell observed, Darwin’s theory is “essentially an extension to the animal and vegetable world of laissez-faire economics.”

I completely agree with that. This is why both Darwin's theory as well as capitalism are the leading paradigms among their competitors. Many general ideas are shared by these two frameworks; other ideas are quite independent.

  • If it is science, why can’t scientists replicate it in microcosm in a laboratory?

Of course that they can replicate many particular examples in their labs. They can't replicate them exactly with the same speed as they occured in Nature because such labs would have to cover 510 million squared kilometers and they would have to work for 5 billion years. Nevertheless, the process can be sped up in many ways, at least in some particular situations.

  • If scientists know life came from matter and matter from non-matter, why don’t they show us how this was done, instead of asserting it was done, and calling us names for not taking their claims on faith?

Let me assume that the first sentence talks about the reheating, to be specific. The reason why I probably can't show Pat Buchanan how different forms of matter or non-matter are transforming into each other according to the laws of quantum field theory or string theory - and why we know that it is the case without any religious beliefs - is that Pat Buchanan apparently does not have a sufficient intelligence to understand my explanations. It's that simple.

  • Clearly, a continued belief in the absolute truth of Darwinist evolution is but an act of faith that fulfills a psychological need of folks who have rejected God.

That may well be the case but such an ad hominem observation is completely irrelevant if there are clear proofs that the picture is correct.

  • Hence, if religion cannot prove its claim and Darwinists can’t prove their claims, we must fall back upon reason, which some of us believe is God’s gift to mankind.

Unfortunately for Mr. Buchanan, this is not our situation because the Darwinists can prove their claims quite convincingly. By the way, the discovery of evolutionary biology is certainly one of God's big gifts to mankind, too. ;-)

  • And when you consider the clocklike precision of the planets in their orbits about the sun and ...

The motion of the planets is exactly predictable by our theories. It is clocklike but not atomic-clock-like. Indeed, we can easily measure the irregularities in their motion - which means, among other things, that we will have to insert a leap second between 2005 and 2006 once again to counterbalance Nature's (or God's?) imperfection, so to say.

  • ...the extraordinary complexity of the human eye, does that seem to you like the result of random selection or the product of intelligent design?

It is the result of very sophisticated laws of Nature - physics, biology, and so on - whose important "emergent" feature responsible for much of the progress is the natural selection. Natural selection is not quite random even though it can sometimes look so at short enough time scales.

  • Prediction: Like the Marxists, the Darwinists are going to wind up as a cult in which few believe this side of Berkeley and Harvard Square.

It would be a bit nicer if only a few around Harvard Square believed marxism. ;-)

Saturday, December 24, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Merry Christmas



Background sound (press ESC to stop): Jakub Jan Ryba's "Czech Christmas Mass" (Hey master, get up quickly); a 41:39 MP3 recording here



Merry Christmas! This special season is also a great opportunity for Matias Zaldarriaga and Nima Arkani-Hamed to sing for all the victims of the anthropic principle who try to live in the bad universes (audio - sorry, the true artists have not been recorded yet):

  • WE WISH YOU A TINY CC
    WE WISH YOU A TINY CC
    WE WISH YOU A TINY CC
    SO YOU GET GALAXIES!

    GOOD TIDINGS WE BRING,
    FROM FROM VILENKIN
    DON'T CRY IF YOUR WORLD SUCKS
    IT'S MUCH BETTER OUT THERE

Friday, December 23, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

E=mc2: a test ... interplay between theory and experiment

An experiment that is claimed to be the most accurate test of Einstein's famous identity "E=mc2" has been performed by physicists on the other side from the Central Square - at MIT.

Their accuracy is 55 times better than the accuracy of previous experiments. They measured the change of the mass of nucleus associated with the emission of energy after it absorbs a neutron. I find their promotion of the experiment slightly dishonest:

  • "In spite of widespread acceptance of this equation as gospel, we should remember that it is a theory," said David Pritchard, a professor of physics at MIT, who along with the team reported his findings in the Dec. 22 issue of Nature. "It can be trusted only to the extent that it is tested with experiments."

Thursday, December 22, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

TeX for PowerPoint: TeX4PPT

Aurora is a new commercial LaTeX system for MS Office
Some readers may have installed TeXpoint as an add-in to their PowerPoint. Let me now mention that

is probably superior and everyone who uses TeX as well as PowerPoint should install this piece of free software. In this framework, you may create a new "text box" using the drawing toolbar. Inside the text box, you may write some $tex$. When you're finished, you right-click and choose TeXify. It will convert the text box into a nice piece of LaTeX. One internal advantage over TeXpoint is that it is directly the DVI that is being converted to Microsoft's own fonts. (TeXpoint was also generating a postscript as well as an image.) This means, among other things, that the text respects the background.

The father of Bott periodicity died

Via David G.

Raoul Bott - a Harvard mathematician who was fighting against cancer in San Diego and who discovered, among other things, the Bott periodicity theorem in the late 1950s - died the night of December 19-20, 2005.

His mother and aunts spoke Hungarian. However, his Czech stepfather did not, and therefore the principal language at home was German. At the high school, on the other hand, he had to speak Slovak. His nanny was English which helped young Bott to learn authentic English. To summarize this paragraph: one should not be surprised that Bott hated foreign languages.

Blog of WWW inventor

The person who invented the World Wide Web has started to write

No, it is not a blog of Al Gore - Al Gore has only invented the Al Gore rhythms. The new blog belongs to Tim Berners-Lee who made his invention while at CERN, and currently lives here in Boston.



Figure 1: The first web server in the world (1990)

MIT talk: a theory of nothing

Today, John McGreevy gave an entertaining MIT seminar mainly about the theory of nothing, a concept we will try to define later. The talk described both the work about the topology change induced by closed string tachyon condensation as well as the more recently investigated role that the tachyons may play for a better understanding of the Big Bang singularity. Because we have discussed both of these related projects on this blog, let's try to look at everything from a slightly complementary perspective.

Defining nothing

First of all, what is nothing? John's Nothing is a new regime of quantum gravity where the metric tensor - or its vev - equals zero. This turns out to be a well-defined configuration in three-dimensional gravity described as Chern-Simons theory. It is also the ultimate "paradise" studied in canonical gravity and loop quantum gravity.

Does "nothing" exist and is there anything to study about it? I remain somewhat sceptical. If the metric is equal to zero in a box, it just means that the proper lengths inside the box are zero, too. In other words, they are subPlanckian. The research of "nothing" therefore seems to me as nothing else from the research of the subPlanckian distances. This form of "nothing" is included in every piece of space you can think of, as long as you study it at extremely short distances. And we should not forget that the subPlanckian distances, in some operational sense, do not exist. I guess that John would disagree and he would argue that nothing is an "independent element" of existence; a phase in a phase diagram. I have some problems with this picture.

Tachyons create nothing

Wednesday, December 21, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

MIT talk: Susanne Reffert

Yesterday we went to MIT to see the talk by Susanne Reffert who will be finishing her PhD under Dieter Lüst and who will probably continue her investigation of string theory in Amsterdam, turning down offers from the KITP and CERN. And it was a very nice talk. First of all, she uses Keynote, an Apple-based alternative for the PowerPoint which reconciles TeX and animations into a consistent whole.

Moduli stabilization of F-theory flux vacua again

There have been too many points in the talk to describe all of them here. They studied, among other things, all possible orientifolded and simultaneously orbifolded toroidal (T^6) vacua of type IIB string theory, their resolution, description in terms of toric geometry, flops, and especially the stabilization of the moduli. One of the unexpected insights was that one can't stabilize the Kähler moduli and the dilaton after the uplift to the de Sitter space if there are no complex structure moduli to start with; rigid stabilized anti de Sitter vacua may be found but can't be promoted to the positive cosmological constant case. Some possibilities are eliminated, some possibilities survive, if you require all moduli to be stabilized.

Recall that the complex structure moduli and the dilaton superfield are normally stabilized by the Gukov-Vafa-Witten superpotential - the integral of the holomorphic 3-form wedged with a proper combination of the 3-form field strengths - while the Kähler moduli are stabilized by forces that are not necessarily supernatural but they are non-perturbative which is pretty similar. The latter nonperturbative processes used to stabilize the Kähler moduli include either D3-brane instantons or gaugino condensation in D7-branes.

At this level, one obtains supersymmetric AdS4 vacua. Semirealistic dS4 vacua may be obtained by adding anti-D3-branes, but Susanne et al. do not deal with these issues.

43rd known Mersenne prime: M30402457

One of the GIMPS computers that try to find the largest prime integers of the form

  • 2^p - 1
i.e. the Mersenne primes has announced a new prime which will be the 43rd known Mersenne prime. The discovery submitted on 12/16 comes 10 months after the previous Mersenne prime. It seems that the lucky winner is a member of one of the large teams. Most likely, the number still has less than 10 million digits - assuming that 9,152,052 is less than 10 million - and the winner therefore won't win one half of the $100,000 award.

The Reference Frame is the only blog in the world that also informs you that the winner is Curtis Cooper and his new greatest exponent is p = 30,402,457. (Steven Boone became a co-discoverer; note added on Saturday.) You can try to search for this number on the whole internet and you won't find anything; nevertheless, on Saturday, it will be announced as the official new greatest prime integer after the verification process is finished around 1 am Eastern time. If you believe in your humble correspondent's miraculous intuition, you may want to make bets against your friends. ;-)

Tuesday, December 20, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Temperatures' autocorrelation

Imagine that the Church would start to control the whole society once again. A new minister of science and propaganda would be introduced to his office. His name would not quite be Benedict but rather Benestad. How would they use scientific language to argue that the Bible in general and Genesis in particular literally describes the creation? They would argue that Genesis predicts water, grass, animals, the Sun, the Earth, and several other entities, and the prediction is physically sound. If anyone tried to focus on a possible discrepancy or a detail, Benestad would say that the heretics were pitching statistics against solid science.

The choice of the name "Benestad" will be explained later.

Do you think that the previous sentences are merely a fairy-tale? You may be wrong. First, we need to look at one scientific topic.

Monday, December 19, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Cosmological constant seesaw

One of the reasons why I have little understanding for the Rube Goldberg landscape machines is that their main goal is to explain just one number, namely the cosmological constant, which could eventually have a simple rational explanation. Let me show you two explanations leading to the same estimate. Recall that the observed cosmological constant is of order

$\rho\approx\frac{TeV^8}{m_{Pl}^4}$
This is almost exactly the same seesaw game with the scales like the neutrino seesaw game. In the case of the neutrinos, we assume the right-handed SU(5)-neutral neutrinos to acquire the GUT scale masses - which is almost the same thing as the Planck scale above - and the unnaturally small value of the observed neutrino masses comes from the smaller eigenvalue(s) of the matrix ((mGUT, mEW), (mEW,0)).

Blogs against decoherence

If you're interested in a blog whose main enemy is decoherence - because they want to construct a quantum computer - see

Everything new you need to know about the realization of quantum bits.

LHC on schedule

2005, the international year of physics, has so far been a flawless year for the LHC. 1000 out of 1232 magnets are already at CERN; 200 magnets have already been installed. See

Update, September 2008: the protons start to orbit in the LHC on September 10th, 9:00 am, see the webcast. But the collisions will only start in October 2008, before a winter break. In 2009, everything will be operating fully. Click the "lhc" category in the list below to get dozens of articles about the Large Hadron Collider.

Distasteful Universe and Rube Goldberg machines

A famous colleague of ours from Stanford has become very popular among the Intelligent Design bloggers. Why is it so? Because he is the unexpected prophet that suddenly revived Intelligent Design - an alternative framework for biology that almost started to disappear. How could he have done so? Well, he offered everyone two options.

  • Either you accept the paradigm shifting answer to Brian Greene's "Elegant Universe" - namely the answer that the Universe is not elegant but, instead, it is very ugly, unpredictable, unnatural, and resembling the Rube Goldberg machines (and you buy the book that says so)
  • Or you accept Intelligent Design.

You may guess which of these two bad options would be picked by your humble correspondent and which of them would be chosen by most Americans. What does it mean? A rather clear victory for Intelligent Design.

The creationist and nuclear physicist David Heddle writes something that makes some sense to me:

  • His book should be subtitled String Theory and the Possible Illusion of Intelligent Design. He has done nothing whatsoever to disprove fine-tuning. Nothing. He has only countered it with a religious speculation in scientific language, a God of the Landscape. Snatching victory from the jaws of defeat, he tells us that we should embrace the String Theory landscape, not in spite of its ugliness, but rather because of it. Physics should change its paradigm and sing praises to inelegance. Out with Occam’s razor, in with Rube Goldberg.

This statement is also celebrated by Jonathan Witt, another fan of ID. Tom Magnuson, one more creationist, assures everyone that if the people are given the choice to choose between two theories with the same predictive power - and one of them includes God - be sure that they will pick the religious one. And he may be right. Well, not everyone will make the same choice. Leon Brooks won't ever accept metaphysics and Evolutionblog simply applaudes our famous Stanford colleague for disliking supernatural agents. But millions of people with the same emotions as William Dembski will make a different choice and it is rather hard to find rational arguments that their decision is wrong because this is a religious matter that can't be resolved scientifically at this point. Discussions about the issue took place at Cosmic Variance and Not Even Wrong.

Intelligent design in physics

Several clarifications must be added. Just like the apparent complexity of living forms supports the concept of Intelligent Design in biology (when I saw the beautiful fish today in the New England Aquarium, I had some understanding for the creationists' feelings), the apparent fine-tuning supports a similar idea in physics. A person like me who expects the parameters of the low-energy effective field theory to emerge from a deeper theory - which is not a religious speculation but a straightforward extrapolation of the developments of the 20th century physics - indeed does believe in some sort of "intelligent design". But of course its "intelligence" has nothing to do with human intelligence or the intelligence of God; it is intelligence of the underlying laws extending quantum field theory.

Opposite or equivalent?

The anthropic people and the Intelligent Design people agree with each other that their pictures of the real world are exactly opposite to one another. In my opinion, this viewpoint about their "contradiction" already means a victory for Intelligent Design and irrational thinking in general. The scientific opinion about this question - whether the two approaches are different - is of course diametrically different. According to a scientific kind of thinking, there is no material difference between

  • the theory that God has skillfully engineered our world, or has carefully chosen the place for His creation among very many possibilities
  • and the theory that there are uncontrollably many possibilities and "ours" is where we live simply because most of the other possibilities don't admit life like ours

From a physics perspective, these things are simply equivalent. Both of them imply that the parameters "explained" by either of these two theories are really unexplainable. They are beyond our thinking abilities and it does not matter whether we use the word "God" to describe our ignorance about the actual justification of the parameters.

Both of these two approaches may possibly be improved when we reduce the set of possibilities to make some predictions after all. For example, we can find which vacuum is the correct one. Once we do so, the questions whether some "God" is responsible for having chosen the right vacuum, or whether no "God" is necessary, becomes an unphysical question (or metaphysical question, if you prefer an euphemism). Again, the only way how this question may become physical is that we actually understand some rational selection mechanism - such as the Hartle-Hawking wavefunction paradigm - that will lead to a given conclusion. Or if we observe either God or the other Universes; these two possibilities look comparably unlikely to me.

Without these observations and/or nontrivial quantitative predictions, God and the multiverse are just two different psychological frameworks. In this sense, the creationists are completely correct if they say that the multiverse is so far just another, "naturalistic" religion.

As they like to say, the two pillars of the religion of "naturalism" - Freud and Marx - are dead. And Darwin is not feeling too well, they add - the only thing I disagree with. ;-) Marx and Freud are completely dead, indeed.

Friday, December 16, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Intelligent Design: answers to William Dembski

William Dembski is one of the most active intellectual promoters of Intelligent Design. He also has a blog

in which he tries to collect and create various arguments and pseudoarguments to support his agenda. Just like a certain one-dimensional blog where every piece of news is projected onto the one-dimensional axis "may it hurt string theory?" - and if the projection is positive, the news is published - Uncommon descent evaluates articles and sentences according to their ability to hurt mainstream biology and to support Intelligent Design.



While I am among those who find all one-dimensional blogs and especially most of their readers kind of uninspiring, let me admit that in my opinion, neither of the two Gentlemen mentioned above seems to be a complete moron and many of their questions may deserve our time.

Dembski vs. Gross and Susskind

Because of the description of the blog above, it should not be surprising that Dembski celebrates and promotes both Susskind's anthropic comments indicating that many physicists have accepted opinions remotely analogous to Intelligent Design - as well as Gross's statement that we don't know what we're talking about.

Incidentally, when Dembski quotes David Gross, he says "remember that string theory is taught in physics courses". That's a misleading remark. String theory is only taught in courses on string theory, and with the exception of Barton Zwiebach's award-winning MIT undergraduate course, all such courses are graduate courses. What the advocates of Intelligent Design classes at schools want is definitely much more than the current exposure of the basic school and high school students to string theory.

Although Dembski and some of his readers may find these quotations of the famous physicists relevant, they are not. Maybe, we don't know what we're talking about when we study quantum Planckian cosmology, but we know what we're talking about whenever we discuss particle physics below 100 GeV, the history of our Universe after the first three minutes, and millions of other situations.

What Dembski wants to modify about our picture of the Universe are not some esoteric details about the workings of the Universe at the Planck scale or the mechanisms of vacuum selection. He wants to revert our knowledge about very low energy processes in physics and biology. That makes all his comparisons of biology with uncertainty in quantum gravity irrelevant.

Scientists may be confused about cutting-edge physics but that's very different from being confused about the insights in biology that have been more or less settled in the 19th century. Some scientists may think that a coincidence whose probability was 10^{-350} had to happen before our Universe was created or "chosen", but they don't need probabilities of order 10^{-10^{100}}

OK, the answers

Finally, let me answer 5 questions from Dembski's most recent blog article about microbiology:
  • (1) Why does biology hand us technical devices that human design engineers drool over?
It is because the natural length scale of human beings is 1 meter. This is the size of humans as Nature created them. This is the length scale at which humans are very good in designing things. I claim that the human engineers are better than Mother Nature in creating virtually any object whose structure is governed by the length scale of one meter. The engineers are also better at longer distance scales - and the trip to the Moon is an example. Engineers had to develop some technology before the humans could directly affect matter at shorter distance scales than the size of our hands. We are getting better and we may get better than Mother Nature in a majority of nanotechnologies in the near future. William Dembski shows a remarkable short-sightedness if he justifies his opinion by saying that Nature is superior over technology - because it is all but guaranteed that technology will be taking a lead and the strength of Dembski's position will therefore definitely decrease with time.

At any rate, even the successes of engineers themselves reflect the miraculous powers of Mother Nature because engineers were created by Her, too. I am afraid that this fact is not appreciated by many advocates of Intelligent Design and many other people.
  • (2) Why don’t we ever see natural selection or any other unintelligent evolutionary mechanisms produce such systems?
Of course that we do. When microprocessors are produced, for example, there is a heavy competition between different companies that produce the chips. Although Intel is planning to introduce their 65 nanometer technology in 2006, AMD may be ahead because of other reasons. This competition is nothing else than the natural selection acting at a different level, with different, "non-biological" mechanisms of reproduction, and such a competition causes the chips to evolve in an analogous way like in the case of animals. (If you want to see which factors drive the decisions about the "survival of the fittest" in the case of chipmakers, open the fast comments.)

Competition also works in the case of ideas, computer programs, ideologies, cultures, "memes", and other things. Indeed, we observe similar mechanisms in many contexts. The detailed technical implementation of the reproduction, mutation, and the rules that determine the survival of the fittest depend on the situation. Some of the paradigms are however universal.
  • (3) Why don’t we have any plausible detailed step-by-step models for how such evolutionary mechanisms could produce such systems?
In some cases we do - and some of these models are really impressive - but if we don't, it reflects several facts. The first fact is that the scientists have not been given a Holy Scripture that would describe every detail how the Universe and species were created. They must determine it themselves, using the limited data that is available today, and the answers to such questions are neither unique nor canonical. The evolution of many things could have occured in many different ways. There are many possibilities what things could have evolved and even more possibilities how they could have evolved.

The fact that Microsoft bought Q-DOS at one moment is a part of the history of operating systems, but this fact was not really necessary for the actual evolution of MS Windows that followed afterwards. In the same way, the species were evolved after many events that occured within billions of years - but almost neither of them was absolutely necessary for the currently seen species to be evolved. Because the available datasets about the history of the Earth are limited - which is an inevitable consequence of various laws of Nature - it is simply impossible to reconstruct the unique history in many cases. However, it is possible in many other cases and people are getting better.
  • (4) Why in the world should we think that such mechanisms provide the right answer?
Because of many reasons. First of all, we actually observe the biological mechanisms and related mechanisms - not only in biology. They take place in the world around us. We can observe evolution "in real time". We observe mutations, we observe natural selection, we observe technological progress driven by competition, we observe all types of processes that are needed for evolution to work. Their existence is often a fact that can't really be denied.

Also, we observe many universal features of the organisms, especially the DNA molecules, proteins, and many other omnipresent entities. Sometimes we even observe detailed properties of the organisms that are predicted by evolution. Moreover, the processes mentioned above seem to be sufficient to describe the evolution of life, at least in its broad patterns. Occam's razor dictates us that we should not invent new things - and miracles - unless they become necessary. Moreover, evolution of life from simple forms seems to be necessary. We know that the Universe has been around for 13.7 billion years and the Earth was created about 5 billion years ago. We know that this can happen. We observe the evolution of more complex forms in the case of chips and in other cases, too.

According to the known physical laws and the picture of cosmology, the Earth was created without any life on it. Science must always prefer the explanations that use a minimal amount of miracles, a minimal set of arbitrary assumptions and parameters, and where the final state looks like the most likely consequence of the assumptions. This feature of science was important in most of the scientific and technological developments and we are just applying the same successful concepts to our reasoning about everything in the world, including the origin of species.

In this sense, I agree with William Dembski when he says that science rejects the creation by an unaccessible and unanalyzable Creator a priori. Rejecting explanations based on miracles that can be neither analyzed nor falsified is indeed a defining feature of science, and if William Dembski finds it too materialistic, that's too bad but this is how science has worked since the first moment when the totalitarian power of the Church over science was eliminated.

  • (5) And why shouldn’t we think that there is real intelligent engineering involved here, way beyond anything we are capable of?
Because of the very same reasons as in (4). Assuming the existence of pre-existing intelligent engineering is an unnatural and highly unlikely assumption with an extremely small explanatory power. One of the fascinating properties of science as well as the real world is that simple beginnings may evolve into impressive outcomes, and modest assumptions are sufficient for us to derive great and accurate conclusions. The idea that there was a fascinating intelligent engineer - and the result of thousands or billions of years of his or her work is an intellectually weak creationist blog - looks like the same development backwards: weak conclusions derived from very strong and unlikely assumptions; poor future evolved from a magnificent past. Such a situation is simply just the opposite of what we are looking for in science - and not only in science - which is why we consider the opinion hiding in the "question" number (5) to be an unscientific preconception. (The last word of the previous sentence has been softened.)

We don't learn anything by assuming that everything has to be the way it is because of the intent of a perfect pre-engineer. We used to believe such things before the humans became capable to live with some degree of confidence and before science was born. Today, the world is very different. For billions of years, it was up to the "lower layers" of Nature to engineer progress. For millions of years, monkeys and humans were mostly passive players in this magnificent game.

More recently, however, humans started to contribute to the progress themselves. Nature has found a new way how to make the progress more efficient and faster - through the humans themselves. Many details are very new but many basic principles underlying these developments remain unchanged. Science and technology is an important part of this exciting story. They can only solve their tasks if they are done properly. Rejecting sloppy thinking and unjustified preconceptions is needed to achieve these goals.

Incidentally, Inquisition and censorship works 100% on "Uncommon Descent". Whoever will be able to post a link on Dembski's blog pointing to this article will be a winner of a small competition. ;-)

Technical note: there are some problems with the Haloscan "fast comments", so please be patient. Right-clicking the window offers you to go "Back" which you may find useful.

String theory is phrase #7

The non-profit organization

located in San Diego, CA, has released its top word list for 2005 (news). The top words are led by "refugee" and "tsunami". Names are led by "God", "tsunami", "Katrina", and "John Paul II". Included are also musical terms and youthspeak.

The top seven phrases are the following:

  • out of the mainstream
  • bird flu
  • politically correct
  • North/South divide
  • purple thumb
  • climate change and global warming
  • string theory

You see that almost all of the words and things that The Reference Frame dislikes are above string theory. The defeat of string theory by the global warming is particularly embarassing. ;-) But the 7th place is not so bad after all.

Concerning political correctness, it is just not the phrase itself that was successful. Many new political correct words were successful, too. For example, the word "failure" was replaced by "deferred success" in Great Britain. On the other hand, the politically incorrect word "refugee" - that many people wanted to replace with "evacuee" - was a winner, too.

Incidentally, Jim Simons, after having discovered Chern-Simons theory and earned billions of dollars from his hedge fun(d), wants to investigate autism.

Sustainability

Roy Spencer has a nice essay on sustainability in TCS daily. The only sustainable thing is change, he says. He also argues that if the consumption of oil or production of carbon dioxide were unsustainable, a slower rate of the same processes would be unsustainable, too.

Sustainability becomes irrelevant because of technological advances in almost all cases. Spencer chooses Michael Crichton's favorite example - the unsustainable amount of horseshit in New York City 100 years ago when there were 175,000 horses in the city. Its growth looked like a looming disaster but it was stopped because of cars that suddenly appeared.

Also, he notices that the employees of a British Centre for Ecology and Hydrology - that had to be abolished - were informed that the center was unsustainable which is a very entertaining explanation for these people who fought for sustainability in their concerned scientific work. Also, Spencer gives economical explanations to various social phenomena. For example, the amount of possible catastrophic links between our acts and natural events as well as the number of types of our activities that will be claimed to be "unsustainable" in the scientific literature is proportional to the amount of money we pay to this sector of science.

It looks like we can run out of oil soon because the companies have no interest to look for more oil than what is needed right now - it is expensive to look for oil. That makes it almost certain that we will find much more oil than we know today.

Pure heterotic MSSM

As announced in October here, Braun, He, Ovrut, and Pantev have finally found an exact MSSM constructed from heterotic string theory on a specific Calabi-Yau.

The model has the Standard Model group plus the U(1)B-L, three generations of quarks and leptons including the right-handed neutrino, and exactly one pair of Higgs doublets which is the right matter content to obtain gauge coupling unification.

By choosing a better gauge bundle - with some novel tricks involving the ideal sheaves - they got rid of the second Higgs doublet. While they use the same Calabi-Yau space with h11=h12=3 i.e. with 6 complex geometric moduli, they now only have 13 (instead of 19) complex bundle moduli.

The probability that this model describes reality is roughly 10450 times bigger than the probability for a generic flux vacuum, for example the vacua that Prof. Susskind uses in his anthropic interview in New Scientist. ;-)

Thursday, December 15, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Something between 2 and 3 billion visitors

This is how you can make quarter a million sound like a lot. ;-)

There is a counter on the right side. If you happen to see the number 250,000, you may write your name as a comment here. The prize for the round visitor includes 3 articles that he or she can post here.

The number 250,000 counts unique visitors - in the sense that every day, one IP address can only increase the number by one. The total number of hits is close to 1 million.

The Reference Frame does not plan any further celebrations. ;-)

Update: Robert Helling and Matt B. both claim to have grabbed 250,000, and I still have not decided who is right. Matt B. has sent me a screenshot so his case is pretty strong. It is academically possible that the number 250,000 was shown to two people - because by reloading, one can see the current "score" without adding a hit.

Lisa's public lecture

I just returned from a public lecture of Lisa Randall - who promoted science of extra dimensions and her book Warped Passages - and it was a very nice and impressive experience. Not surprisingly, the room was crowded - as crowded as it was during a lecture of Steve Pinker I attended some time ago. As far as I can say today, she is a very good speaker. There was nothing in her talk that I would object to and nothing that should have been said completely differently.

As you can guess, I was partially feeling as a co-coach whose athlete has already learned everything she should have learned. ;-)

Nima Arkani-Hamed introduced Lisa in a very professional and entertaining way. Randall used a PowerPoint presentation, showed two minutes of a cartoon edition of Abbott's Flatland, explained what are different ways to include and hide extra dimensions (with a focus on warped geometry), how they are related to some of the problems of particle physics such as the hierarchy problem, how do they fit into the framework of string theory and what string theory is, and what are the methods with which we're possibly gonna observe them. After the talk, she answered many questions from the audience in a completely meaningful way.

Wednesday, December 14, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Coldest December

My time for writing on the blog continues to be limited, so let me just offer you a short provocation. The scientists may have been right after all, the global cooling is coming. ;-) This December will almost surely become one of the coldest American Decembers since the 19th century. Daily record lows have been breached in New York State (10 degrees F below the previous record), the Midwest (Illinois), Utah, Texas (classes canceled), Oklahoma, Colorado, Kansas, Pennsylvania (previous record was 1958), and elsewhere. More snow and cold is forecast. Natural gas is propelled to record.

You may say that it is just the U.S. However, severe cold wave grips North India, too, with at least 21 casualties. The capital sees the coldest day in 6 years. The same thing applies to China and the Communist Party of China helps poor to survive bitter winter. You may complain that I only talk about countries that host one half of the world's population. You're right: the global temperature continues to be stable, around 2.7 Kelvins. ;-)

We are doing fine in Massachusetts, the temperature is -10 Celsius degrees with windchill at -18 Celsius degrees. Tonight, it will be around 6 Fahrenheit. Don't forget your sweaters and gloves.

The consensus scientists have may found a sign error in their calculations. The carbon dioxide causes global cooling. This occassional sign flip is called the climate change.

Tuesday, December 13, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Shut up and calculate

I would not promote overly technical lecture notes, especially not about things covered in many books. But the interpretation of quantum mechanics in general and decoherence in particular - a subject that belongs both to physics as well as advanced philosophy - is usually not given a sufficient amount of space in the textbooks, and some people may be interested in Lecture23.pdf.

Monday, December 12, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Riemann's hypothesis

I just received a lot of interesting snail mail. The first one is from Prof. Winterberg, one of the discoverers of cold fusion. He argues against the extra dimensions, using a picture of naked fat people (actually, some of them are M2-branes) and a German letter he received from his adviser, Werner Heisenberg. Very interesting but I apologize to Prof. Winterberg - too busy to do something with his nice mail and the attached paper.

A publisher wants to sell the 1912 manuscript of Einstein about special relativity. Another publisher offers books about the Manhattan project and Feynman's impressive thesis.

One of the reasons I am busy now is Riemann's hypothesis. Would you believe that a proof may possibly follow from string theory? I am afraid I can't tell you details right now. It's not the first time when I am excited about a possible proof like that. After some time, I always realize how stupid I am and how other people have tried very similar things. The first time I was attracted to Riemann's hypothesis, roughly 12 years ago, I re-discovered a relation between zeta(s) and zeta(1-s). That was too elementary an insight that was far from a proof but at least it started to be clear why the hypothesis "should be" true. The time I need to figure out that these ideas are either wrong or old and standard is increasing with every new attempt - and the attempts become increasingly similar to other attempts of mathematicians who try various methods. Will the time diverge this time? :-)

Sunday, December 11, 2005 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

52.3 percent growth

What is a reasonable size of the GDP growth? 10 percent like in China? 4 percent like in the U.S.? Around 1 percent like in many European countries?

What if I tell you that a particular country had the GDP growth of 52.3 percent in 2004? Moreover, it is a country that is usually described as such a failure that the president of another country who more or less caused all these developments, including the number 52.3, should be hated or maybe even impeached according to hundreds of thousands of activists?

Don't you think that something is crazy about this whole situation? The country has not only a terrific growth potential but also a big potential to become an extremely civilized territory, just like it was thousands of years ago when Europe was their barbarian borderland.

Whether or not these things will happen depends on the acts of many people. Especially the people in that country itself. And also the people from other places in the world, especially America. Who do you think is a better human? Someone who tries to support positive developments in the world, including the country above, or someone who dreams about a failure in that country that would confirm his or her misconceptions that the president is a bad president?

I, for one, think that the members of the second group are immoral bastards. Moreover, it is pretty clear that most of them will spend the eternity at the dumping ground of history, unlike the president who will be written down as an important U.S. president in the future history textbooks.

All those critics who still retain at least a flavor of some moral values: please stop your sabotage as soon as possible. Even if you achieve what you want - a failure - it will be clear to everyone that the failure is not Bush's fault but your fault.