Monstrous developments

Off-topic: a blog of Scientific American: The Simpsons embiggen cromulant papers on string theory

This text is about Witten's proposal that

pure AdS3 black holes carry monstrous symmetry.

There have been various CFT-centered developments here.



First, Jan Manschot (UVA) rewrote the partition sum as an actual sum instead of product, claiming that this form makes it clear that it is a Feynman sum over geometries even though it is not explained too clearly why the individual terms should be interpreted as "geometries".

A week ago, Davide Gaiotto and Xi Yin (HU) have calculated genus two partition sums of these "extremal conformal field theories" or "ECFTs" of Witten. It's an impressive calculation that uses very much the same methods that they know from more conventional compactifications of string theory, further suggesting that neither they nor Witten work on LQG as argued by a supreme crackpot. You should see the formula pi (3.14) on page 9 - the very existence of this solution is a surprise but it exists, in analogy with other stringy miracles. Their methods are effective up to k=10.

A few days ago, Matthias Gaberdiel (ETH) has proposed a general rule for CFTs, especially their modular differential equations whose order should be linked to the vanishing of a certain vector in Zhu's C2 quotient space. This link works in all examples he has checked and if this rule is true in general, Witten's monstrous ECFTs shouldn't exist for k=42 and higher! Recall that the central charge is c=24k. The AdS space wouldn't be allowed to get too large.

If Wolfgang Beirl is still in search of 42, he may find it in Gaberdiel's paper in the role of a killer. ;-)

Witten doesn't want to believe that his theories could be non-existent for k=42 and higher so he proposes a loophole that sounds rather contrived but can't be easily ruled out: namely that there are new states with a high dimension (in the flat space limit) that grows like sqrt(k) that repair the partition sum. ;-)

Well, if I had to make a bet, I would bet that what breaks at k=42 and above is not the sequence of AdS/CFT dual theories by Witten but rather Gaberdiel's link and that Witten's loophole is not needed.

And that's the memo.

Checkers solved: a draw

This month, computer scientists from University of Alberta have announced that their computers have scanned 500,995,484,682,338,672,639 (half a hexillion) board configurations of American checkers, also known as English draughts or Czech madam. Surely, they had to analyze many of them in huge "trivial" classes because otherwise the Hubble time wouldn't be enough.

They have determined the right move for each of them. The main conclusion is that ideal players will end up with a draw:

BBC (popular), Wikipedia, Science (technical)

You may hope that the Flash applet above is imperfect. ;-) The applet has unusual, politically correct priority rules: green goes first. I have easily won but that may be only because I was green.

Some 15 years ago, I (or we) have spent a lot of time with game theory because of an interesting fellow, Karel Popp, who has done a lot of cute things about game theory. I remember having analyzed his game Iuvavum (a Latin name of Salzburg where he was a professor) and many other games and their winning and losing configurations. Painfully enough, I have completely forgotten the rules of Iuvavum.

Don Page defends typicality

Hartle and Srednicki wrote a crisp paper that has sketched the Bayesian methods to evaluate the probabilities that a theory is correct and that argued that the anthropic concept of "typicality" shouldn't influence our evaluation of theories.

Don Page responds. He agrees with many statements and rules by Hartle and Srednicki but he still wants to end up with different conclusions. That's a pretty difficult task. The detailed flow of the paper doesn't make sense to me.

I find Page's criticism illegitimate in these respects:

First, Page seems to argue that Hartle and Srednicki were considering theories where probabilities of alternatives don't sum up to one; I don't realize that Hartle and Srednicki ever did.

Second, Page defines a concept of typicality for an observed dataset in a given theory, by dividing its probability by the probability of a "median dataset". This is strange for several reasons.

1. It is not justified why he picks the median and not another kind of mean value - arithmetic or geometric, for example.
2. It is not justified why he considers any kind of mean at all. The Bayesian formula should already contain everything that is needed to calculate the a posteriori probabilities of the theories, so any ad hoc addition to these rules is clearly wrong.
3. It is not possible to sort the probabilities for different $D_j$ in the first place because the probabilities of $D_j$ depend on how finely we divide the space of possible outcomes to boxes. For discrete pure microstates, we could count individual states, but that's clearly not possible in the general case where either a continuum of pure states or mixed states (a density matrix) must be considered.
4. This whole concept of a randomly chosen ratio involving a randomly chosen "mean" seems as a bureaucratic sleight-of-hand and I see no way how this ugly rule added (?) to the Bayesian inference could ever influence rational considerations.

Third, Page doesn't seem to talk about the prior probabilities $P(T_i)$ at all even though this is precisely where the whole dispute is hiding.

These prior probabilities should be assigned wisely, reflecting our state of ignorance. For example, if discrete different theories are available to explain data, they should be given equal priors. However, when possible theories come in large classes or spaces, it becomes subtle. Do you assign one voice to each member or one voice to the whole class?

The anthropic reasoning, once again, wants to assign voices to individual members of these classes. It's the same approach as the approach of Lee Smolin who sells his/their crackpot discrete models not as one theory but eight theories, assuming that it will increase their appeal by a factor of eight.

This approach reminds me of the blonde woman who is asked whether her pizza should be cut to four or eight pieces: "Only four, eight would be too much for me to eat!" ;-)

The choice of the priors is a somewhat philosophical question but Hartle and Srednicki convinvingly argue that classes of theories with a huge number of elements shouldn't have too high a weight. I haven't noticed that Page discusses this issue.

What is Page's answer to their Jovian thought experiment?

In this setup, two theories, T1 and T2, give identically good and accurate predictions of the data that we could test on the Earth. We may imagine that their predictions are actually indistinguishable whenever some quantities such as temperature and gravitational acceleration resemble those on Earth.

However, T2 happens to differ from T1 in a subtle way: it predicts a new set of molecules or other bound states (with new particles, for example) that will form life in environments such as Jupiter's atmosphere. When you calculate it, T2 predicts roughly six trillions of intelligent beings living inside that atmosphere. Assume that we can't yet observe whether this life inside Jupiter's atmosphere exists - which is a pretty realistic assumption anyway.

The question is which theory, T1 or T2, is more likely according to the available data.

Hartle, Srednicki, rational thinking, as well as common sense dictate that these two theories are equally likely because they are two discrete possibilities that should be assigned the same priors and they give indistinguishable predictions for the quantities we could have measured. It follows that all numbers entering the Bayes' formula are identical for T1 and T2 and these two theories are thus in equally good shape.

According to defenders of typicality, T2 is disfavored about 1000 times in comparison with T1 because according to T2 combined with typicality, we should probably be living inside Jupiter's atmosphere which we don't.

I view the latter argument as an irrational one. It is based on an inherently political notion that some dirty colorful creatures who may live inside Jupiter's atmosphere should have the same voice as we do, in some kind of crucial counting that determines how we evaluate theories. Such a "democratic" assumption could only follow from some kind of equilibrium or an "egalitarian" law that is enforced both on the Earth as well as Jupiter. I hope that at least so far, no such a law that would cover the Solar System exists. More importantly, it didn't exist in the past when both civilizations evolved - which shows that any conclusion based on the assumption that this law operates is unjustified.

Moreover, the "typicality" approach is based on another assumption, namely that "we" could be the Jovian guys, after all. I think that this assumption is clearly incorrect, too. "We" couldn't be the Jovian guys because "we" are defined as those who live around 300 Kelvins and 9.8 N/kg of gravity. The meaningful question that enters the Bayes' formula is whether a theory predicts the right life in these conditions, not how it interprets the word "we". T2 doesn't predicts that we are probably Jovians. No theory can predict such a thing because it is tautologically untrue: the only way to make the word "we" meaningful is to define it as the people who live in 300 Kelvins and 9.8 N/kg. Punishing T2 for this "prediction" that it can't really make is a fraud.

It would be equally wrong to say that T2 is, on the contrary, 1000 times more likely than T1 because it predicts 1000 times more intelligent beings.

Incidentally, I didn't tell you that the Jovian beings have ten brains each and leftist activists demand that each being has ten votes in the General Polls of the Solar System (GPSS) instead of one, thus reducing the influence of Earth from 0.1% to 0.01%. Is that a right thing to do? Clearly, these questions are purely political and in the real world, the outcome would depend on a comparison of political and military forces rather than some ad hoc bureaucratic egalitarian rules. Spoiler: the Earth will win the war.

Summary & challenge

The first argument that implies that T1 and T2 are equally likely sounds solid. If two individual theories predict the same results for situations that we have tested and only differ in their predictions for situations that we haven't yet observed and where we don't know what the right answers are, these two theories must have the same probability, regardless of some egalitarian ideology. Could Don Page or another champion of typicality kindly address this particular thought experiment?

Carbon credits: below one European dime

If you haven't bought an iPHONE yet, you should try NeoPOD

Last time, we dedicated a special article to the price of carbon indulgences when the price dropped below one euro. Today, the 2007 allowance price closed at 9 eurocents.

It doesn't seem to matter that the price plummeted more than 300 times since April 2006: the net worth of the supreme prophet has skyrocketed more than 100 times in a couple of years anyway. The economics rules that control saviors of the world are somewhat unpredictable. ;-)

It is not clear to me what happens with the price of carbon debits when the price of credits goes to zero. At any rate, 2007 may be the last year when you may breathe relatively freely.

The graph under the words "300 times" above also shows the prices for 2008 allowances and 2013 allowances that are near 21 euro per ton in both cases. Of course that these prices will be dictated almost entirely by decisions of the bureaucrats. If they allow a lot of emissions, the prices will go to zero. If they impose genuine restrictions, the prices will be sent towards the actual price of the products one must sacrifice - and that's a very high price. Much higher a price than 21 euro per ton.

Recall that you may drive about 5000 miles with a car to emit one ton of CO2: see the data about grams per kilometer. Surely you would easily pay additional 21 euro for 5000 miles. In other words, the price of 21 euro per ton wouldn't have any discernible impact on your driving. There exist larger emitters who are influenced more but be sure that at 21 euro, the impact will still be small.

This whole game may look like a market but it is not a market because it is all about the central decisions.

And that's the memo.

P.S. You may want to order the Warming Swindle DVD for 8 pounds.

Self-consistency

Sabine writes about consistency and self-consistency, and let me also mention a few words about it.

Vocabulary

First of all, she is very correct that physicists - and especially those for whom English is not the native language - like to use physics jargon in everyday life. I certainly do. You may recognize a physicist because he will use words such as "canonical", "self-consistent", "effective theory", and many others well beyond their range of validity determined by the social conventions of the lay majority.

For example, you may want to Google-search for the canonical keyboard problem. Yes, there had to be someone who has promoted this problem described on my page as a canonical one even though the word doesn't appear in the article itself and I bet that he or she has been exposed to physics education, to say the least, unless he learned the word "canonical" from theology. ;-)

But let met get to the main questions.

Consistency with observations

This is a requirement that every scientific theory must satisfy. If a theory is inconsistent with observations, it's dead. I believe that this is such a simple principle that everyone understands it and it doesn't need any extra explanations and disclaimers except for this one: experiments may also be performed or interpreted incorrectly and it would be extremely foolish to think that experimenters themselves are infallible or even more infallible than the theorists which is certainly not the case.

Self-consistency

This concept is what I really want to talk about because it is vastly misunderstood and underestimated - and perhaps even misunderestimated - by a majority of the people and maybe even a majority of the people interested in science.

Sabine also talks about the adjective "self-contained" and she seems to confuse the two. The word "self-consistent" applied to the Hartree-Fock theory isn't really the same word that describes self-consistent theories although they are related. The correct word for the Hartree-Fock conditions for the wavefunctions would really be "self-contained" because the wavefunction appears on both sides of all equations: it helps to define the equations that the same wavefunction should solve. Moreover, the Hartree-Fock method is not a fundamental theory but a trick to get approximate results in a class of cases and the importance of self-consistency for such approximate methods is much lower than it is for fundamental theories.



Unlike drug addicts, most of us live in a consistent world. This adjective means that it is a world where identical questions always have identical answers and where assertions that can be derived never contradict other assertions that can be derived or the assumptions themselves. More concretely, self-consistency requires that a theory

• only predicts non-negative probabilities (the absence of ghosts)
• predicts that the sum of probabilities of all possible outcomes of given initial conditions is always equal to one (unitarity: this word is sometimes understood to include the absence of ghosts, too); in combination with the absence of ghosts, it follows that all probabilities are also smaller or equal to one
• predicts real values for all observables that should a priori be real (hermiticity)
• can only lead to conclusions that are compatible with the assumed symmetries - such as rotational symmetry, Lorentz symmetry, and especially gauge symmetries; the existence of gauge symmetries is often needed for the absence of ghosts
• only predicts finite values of observables or probabilities; in practice, this requirement boils down to a cancellation of divergences, anomalies, and the existence of a finite number of counterterms (in the case of field theories, the condition is called renormalizability).

These requirements may sound as innocent tautologies but they are not. If one thinks properly, they are really enough to find unique answers to all physical questions in numerous classes. It has actually been done many times in the past and it could have been done in many others if people had been more rational, for example:

• all of special relativity follows from consistency requirements including the two postulates, namely the democracy between inertial frames and the constancy of the speed of light
• all of general relativity follows from consistency requirements including the rules of special relativity in local physics and the equivalence principle
• the existence of light quanta - or at least some restrictions in occupying high-frequecy states of the electromagnetic field - is needed for finiteness of the energy stored in this field
• the existence of pions follows from the existence of forces between protons and neutrons in an effective theory; without them, some probabilities of some collisions would exceed the allowed interval
• the existence of the W-bosons follows from the existence of the beta decay i.e. weak nuclear forces via the finiteness of the completion of the four-fermion interaction
• the existence of an SU(2) gauge symmetry - and thus the Z-bosons follows from the condition of unitarity
• the existence of the charm quark follows from similar constraints or, more group-theoretically, from the SU(2) symmetry at high energies (GIM mechanism)
• once we know the SU(2) and U(1) groups in the electroweak force, the existence of leptons follows from the existence of quarks (and vice versa) via anomaly cancellation that is needed to avoid ghosts
• the existence of neutrinos follows from the existence of charged leptons
• the existence of the Higgs boson below 800 GeV follows from the unitarity of the WW scattering
• the validity of string/M-theory - the unique UV completion of general relativity - follows from the consistency between the postulates of quantum mechanics and general relativity

Some of these conclusions have been confirmed experimentally and some of them will be confirmed in the future. There are hundreds of more detailed conclusions that one can make by "pure thought" and that have actually been made by pure thought. People who think that physicists determine every fact about the physical world by looking at a new experiment in every case are incredibly naive.

Is the requirement of self-consistency an absolute one? Unlike Sabine, I would surely answer "Yes" although this answer depends on the way how we talk about things. If we deal with an approximate theory, it only tells us answers to some questions with some error margins. But if we carefully write these errors as order-of-magnitude estimates O(y) - where y is a variable that can be shown to be small - the self-consistency must still be valid with the same errors. More precisely, it must be possible to prove that there can exist a precisely self-consistent theory that agrees with the approximate theory up to the specified errors.

Quantizing waves on the ocean

Ted Jacobson is quoted as saying that perhaps, gravity shouldn't be quantized just like waves on the ocean shouldn't be quantized. Many people pretend that this statement is a wise, alternative approach to deep questions. I happen to think that it is a deep misunderstanding of all of quantum mechanics and it is erroneous at every step, not only at the level of quantum gravity.

First of all, it is not true even in the case of water. Waves on the surface of the ocean are somewhat non-linear, highly interacting, and complicated in shape. They wouldn't lead to a simple Fock space. Because I want to avoid these complications, let us look at waves inside the ocean. Should the sound waves "be" quantized? Is the pressure of water in a given squared micron an operator that acts on a Hilbert space? You bet.

Every observable in this world is an operator. This fact has been established and everyone who is familiar with quantum physics knows that it has. Moreover, the behavior of squared microns of water is safely within the realm of validity of quantum mechanics. It has been tested there experimentally. It's not an extreme regime of any kind.

So are the water waves and gravity analogous questions? In some respects, they definitely are. In both cases, you should realize that the waves are described by some operators that obey some equations. In both cases, you will find out that the theory describing these operators at long distances - where classical hydrodynamics and classical gravity become valid - breaks down at very short distances. In both cases, you need to find a better theory.

In the case of hydrodynamics, the right solution is dynamics of the molecules of water. In the case of four-fermion interactions, the right solution is a spontaneously broken gauge theory. In the case of gravity, the right solution is string/M-theory.

Are there differences between water and spacetime? Yes, there are. The main difference is that water carries a lot of entropy even if there are no waves. That's what liquids always do. The molecules are arranged chaotically which really means that they can be arranged in many ways and the entropy is high. The Hilbert space of the ocean is not a simple Fock space because even the hypothetical ground state is highly degenerate (it has many possible states in it) and complicated.

We know for sure that the entropy density of empty space can't be high. It is a time component of a four-vector; any nonzero value of it would imply a violation of the Lorentz symmetry. The Lorentz symmetry violation in empty space is tiny (experimentally) and I really think it's zero (theoretically). That implies that the entropy density of the vacuum is tiny (experimentally) and probably zero (theoretically). Moreover, a high value of the entropy density would almost certainly imply a high temperature. But we can measure the temperature of completely empty space. It is zero as opposed to 10^{32} degrees Celsius.

A non-zero entropy density of the vacuum would also destroy most interference patterns because states that differ by a different arrangement of the vacuum - that would surely occur because of the interactions between the vacuum ingredients and the interfering particles and waves - can't interfere with each other. That's another approach to rule out high entropy densities of the vacuum.

The people who imagine spacetime as chaotic liquid are not able to distinguish -273.15 degrees Celsius from +10^{32} degrees Celsius (the Planck temperature) or a vanishing entropy density from +10^{95} per cubic meter (the Planck entropy density). They are not really dignified proponents of fascinating alternative theories of physics. They are people who have completely misunderstood basic concepts in this science and if they continue to misunderstand them for years, it's too bad.

If liquid water is a bad analogy for spacetime, is there a better one? Yes, there is. Metals and crystals are much better because the ground state - a metal or a crystal at 0 Kelvin - is unique, much like the vacuum state of spacetime. That's why in both cases, the entropy density is essentially zero near the absolute zero. The Hilbert spaces of both systems can thus be organized as Fock spaces. The particles are called phonons in the case of metals and gravitons in the case of spacetime.

The vacuum is a kind of metal in the sense that the "atoms" are arranged in a unique way. The Lorentz symmetry (and even the full rotational symmetry) doesn't hold for metals (unless they are fine-tuned) but it holds for empty spacetime. That's a very tough constraint that makes the behavior of gravity more unique than the behavior of metals.

Summary

The world is a tightly constrained structure, a clockwork that works well even though it could a priori break down in millions of ways. The more we know about the world, the more ways how the world could break down we learn. This fact is the reason why careful theoretical reasoning is a sufficient way - and in many cases, the only realistically possible way - to answer certain questions. And the power of theory has clearly been getting stronger as people were understanding physics at a deeper level, especially if the level became less accessible to direct tests. In the long run, this process is guaranteed to continue.

And that's the memo.

2007: another weak hurricane season so far

The climate fearmongers were excited during a strong hurricane season of 2005. It was enough for them to merely suggest that global warming could be behind the storms because fear and superstitions are their closest allies. Many people have constructed quasi-scientific, quasi-religious arguments that the number and strength of the tropical storms has been increasing and should be increasing.



Figure 1: The eye of Katrina, 2005

However, the 2006 hurricane season was very weak. It was below the average. Most quantities dropped more than two-fold and the damages decreased by nearly two orders of magnitude from 2005.

What about 2007? We are at the end of July and we have only seen 2 Atlantic tropical storms. Neither of them has been a hurricane. It's less than 3+1 tropical storms (one was unnamed) that have occurred by July 24th, 2006 and of course much less than 7 tropical storms (3 of which were hurricanes, two of which being major hurricanes) that occurred by July 24th, 2005. Klotzbach's team has predicted 14 named storms, 7 hurricanes, and 3 hurricanes of Category 3 or higher for 2007. That's the newest June prediction; in April, their numbers were even higher, 17-9-5!

By the end of November when the season officially ends, Nature has to add 12 named storms, 7 hurricanes, and 3 hurricanes of Category 3 or higher to match their June predictions and for Klotzbach's team to be right. Good luck: you should better rent a lot of aircraft to fly in circles, Philip. Read "State of Fear" to learn the details. ;-) Also, about 1917 additional hurricanes are needed to realize the predictions of Al Gore. I won't wish good luck to this guy because the irony would be far too obvious.

Relevant links:

2005 Atlantic hurricane season
2006 Atlantic hurricane season
2007 Atlantic hurricane season
National hurricane center

No one seems to be interested in the low number of hurricanes. Only a high number of hurricanes can influence the opinions about the climate held by certain people. That's excusable in the case of ordinary folks who have nothing to do with science; it's not excusable in the case of scientists.

And that's the memo.

David McMahon: String theory demystified

David McMahon has written approximately eight books whose title is "XY Demystified" where "XY" is "Statics and Dynamics", "Linear Algebra", "Signals and Systems", "MATLAB", "Circuit Analysis", "Quantum Mechanics", "Relativity". "String Theory Demystified" is thus the natural followup.

Also, if you have an iPod and six dollars left, you may buy String Theory Protector Skin Decals. These skins not only protect your player but they are even constructed purely from components contained in string theory, including strings, branes, and whatever they become at a strong coupling.

Also, if you don't have time to read Harry Potter 7 and you are nevertheless interested in the main points, you should know that I have done the research for you and there is exactly one such point and it appears on the last page. The abstract says: the scar on his forehead hasn't caused any pain to Harry Potter for nineteen years. ;-)

High-school math: highest correlation with college science achievements

USA Today

According to some research published in Science, the amount of maths taken by high school students is more tightly correlated with successes in college sciences than the amount of biology, chemistry, and physics taken at high school.

You can see that most commenters in USA Today find the link obvious, and so do I. Even Mormons find this fact obvious (click):



When Windows Vista evaluates your computer, the overall rating is determined by the poorest one among the partial ratings. It's because the hardest thing among the essential ones is always slowing you most efficiently: it decides about the overall performance. Mathematics is clearly the most non-trivial and most difficult set of concepts underlying natural sciences: it is the subject that divides the people to those who are "in" and those who are not. It's clearly the case in theoretical physics but to a lesser extent, it is also true in the rest of physics, chemistry, and biology.

On the other hand, the high-school students who have become math haters - and who try to deny that mathematics is crucial in natural sciences and especially in theoretical physics - may be more successful in writing books and blogs addressed to other enemies of mathematics. Am I right, Lee?

You should notice that correlation doesn't imply causation. However, in this case, I think that the obvious explanation of the correlation is a conglomerate of two influences:

• the high-school math education directly influences the access to advanced sciences
• the amounts of both the high-school education and the access to advanced sciences are controlled by a common cause such as the level of pure intelligence.

Left-wing nuts vs Fox advertisers

In the past, we used to believe that because of various reasons, America was immune to a threat of totalitarian systems. I no longer think that these comments are valid. There are various problems in Europe but what the far left revolutionary hordes are doing in America right now has no European counterpart I am aware of.

DailyKos.com and similar webshites don't like Bill O'Reilly. That's not too surprising because O'Reilly likes to expose what these far left-wing hate groups are really all about. Because these commies realize that they are just tiny dwarves relatively to O'Reilly and have no chance to deal with him, they decided to terrorize everyone who is connected with the whole FoxNews channel, either directly or indirectly.

AP: liberals going after Fox advertisers

They have collected signatures of thousands of nutcases all over America who vowed to annoy companies advertising on FoxNews (!!!) with intimidating telephone calls. Tolerating all political attitudes is very nice but if the society can't destroy these carcinogenic segments before it's too late, it will be too late and they will destroy the society. And if you have any doubts that the previous assertion is true, let me assure you that it is actually a tautology.

Is it really legal in America to organize a threatening campaign of hateful junk telephone calls?

These activists are fully analogous to the brownshirts in Germany of the 1930s. They are ready to destroy anyone who dares to block their scary revolutionary agenda, all of their relatives and collaborators, and I am telling you: do something about this scum before it's still relatively manageable, otherwise you will be really sorry about your passivity in the future.

And that's the memo.

Gravity from spin-two gauge invariance

Yesterday, a blogging critic of physics argued that physics is a corrupt science that has no credibility. The author of these statements is an "improved" version of Peter Woit and Lee Smolin.

The latter individuals only argue that physics has no credibility if it requires brains that are stronger than their brains while the improved crackpot, let me call him Swolin Plus, also includes all of experimental physics, among other things, to his list of blasphemies.

What arguments does the recent crackpot use? Well, they're not really arguments. He misinterprets another posting by Christine Dantas, a woman from Latin America, who was impressed by a 2004 paper by a somewhat irrational physicist named T. Padmanabhan.

I remember that paper very well because I was asked about it and studied it in detail back in 2004: see also my text on sci.physics.research. We have also exchanged some e-mails with Prof Deser, one of the main people who have contributed to proofs of various theorems discussed in this text. Prof Deser was obviously irritated by the apparent inability of T. Padmanabhan to understand any rational arguments and proofs after a long chain of e-mail exchanges between these two Gentlemen.

Higher-spin gauge invariances

Perturbative string theory may be used to show that massless particles can only have spins 0, 1/2, 1, 3/2, 2. This conclusion follows from an analysis of the energy of various harmonic oscillators included in the string that contribute to the mass of the resulting particle. This conclusion beautifully agrees with facts about gauge invariance that may be derived using spacetime arguments.

If you consider any semirealistic physical system, it reduces to quantum fields at long distances - fields that are able to create particles. Because of the rotational symmetry, these particles may be classified according to their spin. For spins equal to 0 or 1/2, one only creates states of positive norms (think about the Klein-Gordon and Dirac fields). However, for spin 1 and higher, there are inevitably negative-norm states in the Hilbert space created by the simplest version of these quantum fields. For example, the time-like component of a 4-vector field creates states whose norm has the opposite (negative) sign than the space-like components of the same field.

Positive probabilities require a certain kind of beauty

Indefinite Hilbert spaces are unacceptable because they would lead to predictions of negative probabilities. Nature can't afford such bizarre things: negative probabilities would make Her mentally sick. She has one choice only: to decouple all the states with the wrong norm - and perhaps some additional states. If these wrong particles are decoupled, they don't interact with the rest of physics and become harmless.

Such a decoupling implies an infinite amount of accidents that are equivalent to a symmetry. In fact, it is a gauge symmetry. The adjective "gauge" means that the parameters of the transformations are functions of spacetime coordinates.

I prefer this quantum discussion because our world is quantum, after all. In a classical world, the inconsistencies caused by the absence of a gauge symmetry wouldn't be that terrifying - there are no negative probabilities in a classical theory because there are no probabilities there at all. However, they would imply some kind of instability. Let me return to the quantum setup because it is the right one anyway.

Because negatively-normed states must be eliminated for all fields with spin 1 or higher, we must find a corresponding gauge invariance. At the linearized level - where you only keep the quadratic parts of the actions - you essentially know what the gauge invariance for a higher-spin field must be. For spin-1 fields, you obtain

$\delta A_\mu = \partial_\mu \lambda$

while the higher-spin fields have additional subscripts of $A_\mu$. The parameters of the gauge transformations $\lambda$ receive some Lorentz vector indices, too, and the prescription for the infinitesimal transformation above may be supplemented with a few terms that differ by a permutation of the Lorentz vector indices. Half-integral fields also need a spinor index and gamma matrices may occur on the right-hand side.

When you analyze what kinds of gauge invariance are able to make all the dangerous negative-norm states harmless, you will find out that at the linearized level, the spin-1 fields need the electromagnetic gauge invariance described above, spin-3/2 fields require a linearized version of local supersymmetry, and the simplest spin-2 fields - symmetric tensors - force you to impose the following gauge invariance:

$\delta h_{\mu\nu} = \partial_\mu v_\nu + \partial_\nu v_\mu.$

We will roughly understand later why it is not too interesting to consider higher-spin fields. Also, you should notice that differential forms of rank p always generate spin-1 particles only (as opposed to spin p, for example). The maximum value of $J_{xy}$ equals one (in any spacetime dimension) because in a complex basis of $J_{xy}$ eigenstates, you are not allowed to repeat the indices $x+iy$ because of the antisymmetry of the tensor. Of course, massless differential forms are allowed (and frequent) in string theory, too, and it is no contradiction: their spin equals 1.

Both actions and the transformations may (or must) be deformed

The quadratic actions are not too interesting because they don't lead to any interactions. If you want to create a general enough, interesting, interacting theory, you must allow cubic and higher terms in the action. Also, you must be general and allow non-linear terms in the fields and the transformation parameters as your recipe for the gauge transformations: the first major problem that Paddy wasn't able to understand, after months of studying this simple problem.

Because gauge transformations form a group and groups are rather constrained, rare mathematical objects, there are not too many ways how you can add non-linear terms to the gauge transformation. For spin-1 fields, you inevitably end up with a Yang-Mills theory if you impose other physical requirements. For spin-3/2 fields, you end up with supergravity theories and an inclusion of gravitational spin-2 fields is forced upon you as a bonus. More generally, for spin-2 fields, the only mathematically meaningful non-linear modification of the transformation expressed above is

$\delta h_{\mu\nu} = \nabla_\mu v_\nu + \nabla_\nu v_\mu$

or something that is related to it by a field redefinition. The nabla derivative above includes the usual term with the Christoffel connection calculated from the metric

$g_{\mu\nu} = \eta_{\mu\nu} + h_{\mu\nu}.$

The original linearized gauge group that was isomorphic to some kind of $U(1)^\infty$ is deformed into the diffeomorphism group. The resulting class of theories with gauge-invariant actions that are allowed in this framework is equivalent to general relativity written in terms of variables $h_{\mu\nu}$ instead of $g_{\mu\nu}$. But it doesn't matter how you write things and what conventions or variables you use. What matters is physics: a fact that the broader loop quantum gravity community will never be able to understand due to their intrinsic mental limitations.

The tensor that is coupled to the field $h_{\mu\nu}$ must be conserved and it turns out that only if you choose anything else than the stress-energy tensor, the conservation of such a current will constraint the theory so severely that the interactions become impossible. That's why the spin-two fields are coupled to stress energy tensor in all interesting theories.

For the symmetric tensors i.e. spin-2 fields, you will see that deforming the Abelian gauge invariance into the diffeomorphism group is de facto the only way to get interesting interacting theories and the gauge invariance constraint leads to the same class of theories as the diffeomorphism symmetry usually dictated by general relativity - because it is really the same thing. Extra terms can be classified according to their dimensions - including the number of derivatives - as particle physicists like to do.

The trivial solution is just a limit

In fact, the "other" solution, namely to keep the Abelian gauge symmetry, is not a genuine new solution. The Abelian gauge symmetry for spin-2 fields we started with - one with partial derivatives instead of the covariant derivatives - is a contraction of the diffeomorphism group or, in other words, a limit of the diffeomorphism group for a vanishing Newton's constant.

All other examples of theories with tensorial gauge symmetries require an infinite number of massless fields and their interplay (see "massless higher-spin theories") - and they are thus not too physical.

You might think that it is sensible to treat theories with a vanishing Newton's constant - but non-vanishing higher-derivative terms - as a special class. But the renormalization flows really discourage you from this kind of thinking because if Newton's constant is vanishing at one energy scale, it is typically not vanishing at another scale. The "subclass" mentioned previously can't really be separated from the diffeomorphism-symmetric theories in a renormalization-flow-invariant way.

The same analysis of possible non-linear deformations implies our previous conclusions for other values of the spin: Yang-Mills theories are the only nice new theories for spin-1 fields, supergravity is the only nice solution for the spin-3/2 case, and there are no interesting theories of massless particles with spin greater than two. Moreover, even massive spin-1 theories are constrained: the gauge symmetry must always be broken by some kind of Higgs mechanism.

In string theory and quantum gravity in general, there are many massive particles with much higher spins but the quantum field description becomes unusable in all these cases. These massive high-spin fields depend on the whole infinite tower of string states, including the massless ones, and the solutions of string theory are the only new loopholes of the otherwise strict rules of local effective quantum field theories with gauge invariances.

Summary

There are robust and reliable spacetime arguments constraining possible spins of massless fields and the form of their interactions derived from gauge symmetries. These conclusions agree with the known types of massless spectra in various vacua of string theory even though these facts are derived very differently in string theory than they are derived in effective field theory.

Paddy's paper has had two parts that were both wrong. One part was wrong because

• he didn't realize that one must allow non-linear terms in the gauge transformations which is why he missed the "bulk" of this class of theories, namely theories equivalent to generally covariant theories (gravitational theories) - the real meat of this whole enterprise
• he didn't realize that the class he considered, one with Abelian gauge invariances, is a special, measure-zero subset of the previous generally covariant class that can't be separated in a renormalization-flow-invariant way
• moreover some of the "new" gauge-invariant actions he proposed were not really gauge-invariant because of technical errors in his calculations

At any rate, all this stuff shows that Paddy hasn't really understood the old papers to start with. What he wrote is a summary of his confusion, not a path to a new result in science. But you can see that wrong papers are immediately abused by all kinds of crackpots and science-haters, and because most journalists in the present era are also science-haters, to one extent or another, a variant of these anti-physical sentiments is often sold to the general public.

That's not too good. Needless to say, the situation with crackpots such as Peter Woit and Lee Smolin is analogous. The content of all criticisms of science by these people - especially their fanatical anti-mathematical sentiment - is a pure reflection of their own severe intellectual limitations and 100% of support of this crap in the society is created by combining the screams of people who are equally stupid and dishonest as Smolin and Woit or even more stupid and dishonest.

A sensible reader of newspapers and blogs will never pay too much attention to millions of ignorants and morons who have no idea about the subject. You have always a much higher chance to find the correct answer if you ask one person who actually knows what he is talking about.

And that's the memo.

Václav Klaus: An interview in die Weltwoche

Translated from German

Mr President, climate change is currently a frequently discussed topic. Meanwhile, you state that global warming is a myth of environmental fundamentalists. Why?

Climate change has become a fashionable topic. Many politicians and scientists use it even if they don't believe global warming.

Isn't the current warming a fact?

The facts are not clear. In the last century, the global average temperature only rose by 0.6 degrees Celsius. It is too little to create a panic. Also, it is no secret that the Earth has had much warmer climate in the past than it has today. The second question is whether the recent mild warming is actually caused by human activities. We don't know yet. What I do consider as a threat is this environmentalism that has become a religion that wants to inhibit the spontaneous evolution of mankind. The champions of this ideology want to create a society that is restricted by hundreds of regulations and prohibitions. The freedom would become a victim.

You are an economist, not a climate expert. Where do you find the credentials to be so radical?

My attitude is completely normal. It surprises me again and again that some people see something radical in it. Moreover, the main concern of mine is not climatology. What I care about are the consequences of a potential climate change; an analysis of the human adaptability; a calculation of the costs tightly connected with a fight against the climate change. Humans, their behavior, and their motives are in the center of my interest.

Would you agree with the thesis that the politicians chose the climate because they haven't found another topic that is equally vague and can create consensus equally easily?

It is an obligation for all of us to protect Nature and preserve Nature for future generations. Nevertheless, I am convinced that a sincere interest in the protection of the climate only plays a minor role in the rhetoric of many politicians.

It seems, Mr Klaus, that you deliberately create your image as a defender of the opposite thesis.

I happen to think that the liberty is threatened. And liberty is the main topic of our time and the topic of my life. It seems that one can find a stronger desire to argue and more aggressiveness on the side of my opponents.

Environmental activists argue that the widespread belief in the economic growth is reponsible for climate change. Are they right?

The economic growth is the solution of the environmental problems, not their cause.

Meanwhile, the topic has gained a high priority even in the commercial sector. Everyone asks what his company can do to protect the climate. Many enterprises want to be politically correct. This topic has thus become a convenient political card that they occassionally play with. This card turns out to be profitable, too: the government gives the firms wrong signals - together with subsidies - that influence them more than the desire to be profitable.

Why do you pay so much attention to this topic?

What I already find worrisome is how easily some people are ready to place the world and the mankind on a new basis because of some disputed data and hypotheses; how they predict what is happening in the world and what will happen in the future; and how they want to impose completely extreme regulations and, concomitantly with it, a delimitation of the liberty. That's neither a marginal footnote topic for me nor a deliberate attempt of mine to become visible.

You have written an environmental book. What else do you have to tell the world?

What concerns me are not measurements of temperatures even though they naturally play a role. What I care about more is whether humans partially cause the climate change and whether this influence is strong enough to justify the prevailing hysteria. What I am concerned with is whether the society is going to change its structure and spend enormous amounts of money whose positive or perhaps negative effects will only be visible in the next century.

Die Weltwoche (The World Week), 07/26/2007

Internet ADSL

As a small kid, I was kind of impressed that one wire - or the air in your room - can support all the information needed for dozens of radio and TV stations. You don't see anything but it's there.

Well, rationally speaking, I am no longer stunned by this fact, having known something about the Fourier analysis and resonance, among other things, for almost two decades. But each person has some irrational core, too. It is still fascinating that the same old telephone cable is now able to connect the world not only with a telephone but also with two computers at 2 Mb/s. The installation worked very smoothly and all worries about Vista incompatibilities turned out to be entirely unjustified.

Also, I remember the worries about the inflexible communication market in the Czech Republic a few years ago. These worries seem so distant today... The former socialist telephone provider became a part of Eurotel and more recently a branch of Telefónica, a Spanish (now global) communication company. Everything from them uses the following logo:



Yes, it looks like oxygen: the bubbles as well as the O2 employees are informally nicknamed waterfarts (vodoprdy), indicating a mixture with CH4. Their service looks nearly perfect to me. Still, they face a lot of competition in all the markets - classical phones, cell phones, digital TV, mobile internet, and others. Nevertheless, it will take several days before some meaningful or even valuable articles reappear on this blog. Have a nice end of July, Luboš

U3 launchpad for Windows Vista and Microcenter USB flash drive

Many of you who have used search engines to get to this page may have bought the USB flash memory chip from Microcenter, with the Microcenter logo on it. And you have found out that the U3 application doesn't work under Windows Vista (Home Basic, Premium, Business, Ultimate, or anything else).



There exists a solution. What the cashier at the Microcenter hasn't told you is that the drive wasn't produced by the cashiers, janitors, and bean counters at Microcenter, despite the logo. It had to be produced by someone else. The magic code of "someone else" is IPSG. Click at

IPSG products: USB storage

and choose either the 1 GB black drive (second product) or the 2 GB black drive (third product), depending on your disk capacity. On the following page, you find your U3 software for Vista (second link). The ZIP file may be unpacked by a double-click. There are two PDF files of documentation in the archive that you may ignore and also one EXE file that you run. It will update your U3 software to be compatible with Windows Vista. Don't remove your drive from the USB port during the installation process, otherwise you may damage your drive, and good luck!

For users of other USB flash cards

We should say that more generally, the U3 launchpad version 1.4 or higher co-operates with Windows Vista. But you should still be careful about the version of the drivers and software you install: you should better look at the website of the manufacturer of your flash card.

Updating

Incidentally, I clicked "OK, install" and allowed a new version of the drivers and U3 software from Sandisk to be installed instead of the version 1.4 - even though the manufacturer of the Microcenter flash memory is not exactly Sandisk. It works both on XP and Vista, including ReadyBoost, so don't be afraid to update the flash software.

Veneziano & Gasperini: book

I should get an ADSL modem and a permanent connection within days and blogging could get somewhat more serious. So far, you may write whatever you like about the new book by Gasperini and Veneziano, to be released on August 1st. You may already pre-order it.

Bussard fusion: funding from California

Read here... Update: the page under the link is updated and the rumors were probably not true.

Michael Moore causes global warming

Backreaction rationally analyzes an article in Nude Socialist that argues that "it is becoming clear that obese people are having a direct impact on the climate". Bee has some comments about the actual flow of energy in this context.

The author doesn't distinguish global warming and wasting of energy and moreover is unable to calculate that the "obese" contribution to CO2 emissions is negligible. Simple formulae such as "global warming = waste of energy = fat people" are characteristic formulae of religions: "devil = sin = blasphemy = criticism by preachers = burning at stake". It is the very goal of religions to make people unable to distinguish more than two nouns, two adjectives, two scientific concepts. Everything is black or white and any deeper analysis becomes impossible. That's good because all believers want to be "100% white" which is why they're 100% manipulated by the church.

If we were living in a sane world, the author would simultaneously publish an explanation in another journal that would reveal that the text in Nude Socialist is a hoax whose goal is to demonstate poor intellectual standards of the journal.

However, we don't live in such a world which is why the author who wrote it is a genuine bearer of an alternative mental infrastructure himself. (I hope that this synonym for a nutcase is sufficiently politically correct.) Moreover, believe me or not, he is a professor. Is Michael Moore going to continue to support the global warming movement under these circumstances? What if the religion suddenly decides that fat pigs must be sacrificed to Gaia?

We report, you decide.

Forests around the radar

On Sunday, we decided to make a trip to the place where the U.S. radar may be built which is near the Míšov village in the Brdy Hills, less than 30 miles Southeast from Pilsen.

There are nice, untouched forests around: dozens or hundreds of squared miles were (or are) used as a military training area. However, we completely ignored all the access restrictions. There was no one there who would care. A fancy golf course is nearby, too. The people who live in these villages are ordinary Czechs, the kind of people whom we are used to meet every day. Most of them don't want the radar.

However, what I found even more striking was that the locals had essentially no idea about the radar. They didn't know where it should be located: not even the guy who sold us the sausages and the beer and who works one mile from the key spot had any clue about the location. They didn't seem to care.

Eventually I found the right person who explained me that the radar should be built on a peak that is 718 meters above the sea level and how we can get there. When you walk (or bike like my friend or drive your small motorcycle like your humble correspondent) through the deep forests, you see that one radar facility - one percent of a squared kilometer? - doesn't change much about the landscape. It's negligible.

Because of these two reasons - ignorance of the locals and the depth of the forests - I have thus decided that it is absolutely correct that the local referenda don't influence any decisions about the project. The local people don't own the forests and the project won't influence them in any way. Unless Putin or another leader decides to exchange nukes in a piece of a Czech forest for nukes in the Red Square which I find much less likely than a proclamation about the same act, they won't even notice. ;-)

Because one project of this kind doesn't change anything about the membership of the country or the obligations of its citizens etc., I also think that a national referendum is unnecessary.

The main significance of the project is a global one. And I would say that even the global meaning of the radar is mostly symbolic. It is not easy to present a convincing calculation showing that the U.S. security or the security of its allies will significantly increase when all direct and indirect consequences of the project are taken into account. I see the defense system primarily as a sign that tells the world that the U.S. and some other developed democratic countries want others to forget about wars and attacks and the thoughtful part of the Czech Republic doesn't want the democratic world to be attacked either.

And that's the memo.

P.S. Soon after we left the forest, my motor's power plummeted to about 50 percent and the motorbike became unable to climb any hills while the maximum speed on horizontal roads dropped to 10 mph or so. Not only I became unable to push Víťa who is not exactly another Lance Armstrong - he had to rely on his muscles in the second part of the 65-mile trip instead - but I had to use the pedals, too. Pedalling your heavy motorbike in a hilly area for 30 miles is not the most joyful experience in the world but I survived. ;-) So far, no one is sure how to fix it...

Nir Shaviv: Why is Lockwood and Fröhlich meaningless?

One of the newest articles at RealClimate.org contains a link to the full text of a recent article by Lockwood and Fröhlich who argue that "all" potential aspects of the Sun in the last 20 years that could be responsible for warming in that period went the wrong way. Well, there are many questions: for example, was there a warming that one should talk about? There wasn't one in the last ten years.

A more important question is whether their whole article is correct. I haven't quantitatively verified Nir Shaviv's answer below but I feel that the view of this Israeli expert is way more relevant than the childish comments about coffins by the RealClimate.org zealots and it surely makes sense qualitatively, so let me reprint it. The text below is from Nir.

Why is Lockwood and Fröhlich meaningless?

L & F state that from 1985, there is a discrepancy between solar activity, which decreased, and the global temperature, which increased. Hence, solar activity cannot explain the observed warming. This conclusion, however, is flawed for several reasons.



Figure 1: Cosmic ray flux as a function of time. Note the minimum near 1992 that probably caused less cloudiness and warming in the 1990s

To begin with, L & W write that solar activity decreased after 1985. This may almost be correct for the sunspot number (which remained the same) and perhaps correct for other solar activity proxies, but this is not correct for the cosmic rays. As is apparent from the first two figures above and below, the 1990 solar maximum caused a larger decrease in the cosmic ray flux, which implies that the temperature should have been higher in the 1990's than in the 1980's. This leaves a discrepancy between the solar maximum of 2001 which was weaker than the solar maximum of 1990, and the observed temperature increase.



Figure 2: This inverse correlation between a smoothed international sunspot number (green) and three graphs (thin lines) depicting cosmic ray flux seems obviously valid.

So why has the temperature continued increasing even though the solar activity diminished? This has to do with the second point, which is very important, but totally ignored by L & F.

L & F assume (like many others before) that there should be a one-to-one correspondence between the temperature variations and solar activity. However, there are two important effects that should be considered and that arise because of the climate's heat capacity (predominantly the oceans). First, the response to short term variations in the radiative forcings are damped. This explains why the temperature variations in sync with the 11-year solar cycle are small (but they are present at the level which one expects from the observed cloud cover variations... about 0.1°C). Second, there is a lag between the response and the forcing. Typically, one expects lags which depend on the time scale of the variations. The 11-year solar cycle gives rise to a 2-year lag in the 0.1°C observed temperature variations. Similarly, the response to the 20th century warming should be delayed by typically a decade. Climatologists know this very well (the IPCC report, for example, includes simulation results for the many decades long response to a "step function" in the forcing, and climatologists talk about "global warming commitment" that even if the CO2 would stabilize, or even decrease, we should expect to see the "committed warming", e.g., Science 307), but L & F are not climatologists. They are solar physicists, so they may not have grasped this point to the extent that they should have.

Incidentally, this is not unlike a very well-known effect from everyday life. Even though the maximum radiation from the Sun is received near noon time, the maximum daily temperatures are obtained a few hours later in the afternoon. If we were to correlate the falling radiation between say noon and 3 pm (or between June 21 and July-August), to the increasing temperature over the same period, we would conclude that solar radiation causes cooling! This is exactly what L & F are doing. They are ignoring the fact that over the 20th century, solar activity increased tremendously (see the third figure below). So, even though the 2001 maximum is weaker than the 1990 maximum, we are still paying for the extra heat absorbed over several decades, from the middle of the 20th century.



Figure 3: Tremendous increase of solar activity in the last 100 years

In fact, if you look at the total heat in the oceans, you will see that from 2001 it actually decreased! (Well, recently, after the inconvenient buoy data was removed, the heat content stopped increasing.) This lower heat content should start to cause a prolonged cooling, assuming the solar activity will remain at the 2001 level or lower.

Moreover, if you look directly at the mechanism through which solar activity affects climate, that is, the amount of cloud cover, you do see that the amount of cloud cover decrease in the 2001 maximum is smaller than the decrease in 1990. As it should!

Thus, when you look at the whole picture, there are certainly no inconsistencies in the solar/climate picture. Au contraire.

And that's Nir's memo.

For criticisms written by others, see Climate cuttings 7 and Warwick Hughes. A new document by Henrik Svensmark and Eigil Friis-Christensen is a reply to the article by Lockwood and Fröhlich. Many graphs are extended up to 2007. The figure 2b is a particularly impressive agreement between cosmic rays and temperature although one had to subtract El-Nino effects, the North Atlantic oscillation, volcano aerosols, and a linear trend to make it that good.

Bonus articles related to climate change on The Reference Frame

• 1934 beats 1998 as the warmest U.S. year
• Greenhouse effect and saturation
• C. Monckton & panic about warming
• Dr Oreskes & myth about consensus on global warming
• Temperature drove CO2 ppm numbers, not the other way around
• IQ2 US duel: climate realists beat alarmists
• Relationship between the sun spots and cosmic rays - and temperature
• 2006: a list of bad news for the alarmists
• 2006: coolest year after 2001

Windows Vista: some actual experience

One of the reasons why I didn't have much time during the week was that I bought a new PC with Windows Vista Home Premium (CZ) and had to copy my data and software on it. With a 2 GB flash card, the transfer of 20 GB takes some time because the old XP laptop offers USB 1.0 only. The (crossed) ethernet cable in principle worked - they recognized the name of the partner - but I wasn't able to make the two computers fully collaborate and share general data through the cable.

If you care about the hardware, my old laptop is Hewlett-Packard Pavilion ze4125 while the new desktop PC is Packard-Bell iMedia, a no-name brand that looks similar to Hewlett-Packard which might be a deliberate trick by the French comrades who produce the boxes. Analogously, iMedia might have been chosen to induce a confusion with Apple. ;-)

The PC has 1024 MB, 3.3 GHz Intel Celeron, ST 160 GB disk, Optiarc DVD-RW, and an ATI video card that steals 256 MB RAM. The minimalistic Made-in-China English-Czech keyboard has one incredibly annoying subtlety: the right portion of the left shift key is stolen and transformed into another copy of the backslash-vertical-line key that exists elsewhere on the keyboard anyway. Because the left shift key has been pretty important for me - most capital letters are typed with the key pressed - destroying the most important sensitive spot of this key is a kind of problem! :-) The general secretary of the Chinese communist party should execute the person who has designed such a keyboard even though I guess she wasn't Chinese. ;-)

At any rate, now I can tell you much more about Vista than in the past when I dared to speak after 20 minutes of playing with it in Microcenter. My new comments finally include some negative words which were absent in my primordial, naive testimonies. ;-)

Speed and design

Vista is fast but I guess that booting could be faster with XP using the same new hardware. The transitions are smooth and most things look visually attractive. Waiting has been eliminated from many clicks that used to be time-consuming in XP but that could be largely due to the faster hardware, too.

Note that the Home Premium edition is not the minimal version of Windows Vista Home. Vista Home Premium is more successful than Vista Home Basic. I am almost sure that it is because of Windows Aero, the theme including semi-transparent borders of the windows: it is incorporated in all editions except for Home Basic. You can actually see a fuzzy, dim picture of the window behind it. Your humble correspondent usually doesn't care about such superficial details but if you see him care, it is likely that many others will care, too - even if they won't admit it. ;-)

Windows Aero is cool but you must carefully choose your favorite color and the degree of transparency.

Start menu and indexing

The start button only includes a windows logo: the word "start" was a clear waste of space, at least after one minute when you learn what the start button is. When you click at it, things look much like in XP except for a few things. The most important one is a small window in the bottom that allows you to make a fast search for anything on your computer. The search looks at all filenames and the content of all files with text. As far as I am concerned, this improved and integrated MSN Desktop Search supersedes Google Desktop Search and in this case, I don't plan to install Google's competition although Google should probably be praised for their priority.

It seems that hibernation has been abolished - or, if you use the official terminology, it's been unified with the stand-by mode. I don't yet know whether the computer's power consumption is negligible in the stand-by mode. If it is, hibernation might indeed be useless, at least for desktop PCs.

What I find illogical is that there are no icons in the right column of the start menu (documents, computer, pictures, music, videos). As far as I can say, in all similar standard situations, it is easier to navigate through icons. The icon of the selected folder nevertheless appears on the top of the start menu, instead of the user's icon. Games have been included as a pretty standard category besides pictures, music, video, and (text) documents - and there is a dozen or so of simple Microsoft games included.

Windows explorer

The windows explorer has been significantly updated. In Windows XP, sorting and grouping according to various criteria was modestly presented as a new idiosyncratic subtlety that had to be hidden somewhere in complicated menus. That's no longer the case. Microsoft has recognized that these are standard tools that are used all the time. By one click, you can re-order and re-group the files in the directory according to dozens of different criteria that you can pre-configure if you wish and that depend on the content of the folder. By one click (a different one), you may also switch from the list to tiles (my favorite choice) and to small icons, medium icons, and large icons (or thumbnails). That's clearly a good thing.

In XP, you had a left column with context-dependent tasks (such as "make a new folder"). I have never used these buttons much but I liked them aesthetically. In Vista, a list of relevant folders is positioned in the left column but can be removed which is my favorite choice. You may also add a right column with previews.

There are two visual aspects of the content of the explorer's windows that I view as setbacks in comparison with XP. One of them is the uniformity of the color. In XP, the tasks in the left column used to have a different background color (blue). Such a combination of different colors (of both text and the background) resembles the template of this blog and in my opinion, it is not only visually appealing but it also helps you to quickly realize the decomposition of the page to different fields.

In fact, I would find it natural if different kinds of folders were associated with different background colors etc. For example, music folders could have different background and text colors than document folders, external disks, or pictures. That would make the orientation more convenient. Right now, even the difference between the active and other windows is too subtle. If you open too many windows of the explorer, you create a kind of chaos and neither the task switch button involving thumbnails (alt-tab) nor its brand new three-dimensional card version (windows-tab) helps you to get out of this chaos too efficiently if too many windows are too similar. Also, I would like a Norton-commander-like double-windows to make copying and moving more transparent.

The other complaint of mine is that the fonts describing files and their groups look too thin. Boldface fonts should be used at least for the groups of files (the titles). I still find the tiles and filenames as seen in XP to be more solid and comprehensible than their Vista counterparts. And I continue to have mixed feelings about the different size of the desktop icons: of course, all these things are matters of taste that can change. Vista's desktop icons are larger and most of them are available in a sufficient resolution but you will surely encounter some low-res examples soon if you have ever played with them.

The explorer has been given integrated search windows - using the indexing system - which is clearly a thing that all good operating systems in the future will have to have.

Other viewers, calendars, and applets

There exists another application analogous to the explorer that is somewhat non-trivial. In the Czech version, it is called Windows Photo Gallery. You may either understand it as a huge upgrade of the picture viewer and slide shows from XP, or as an integrated counterpart of Google Picasa2. Picasa2 is cool but as far as I see right now, it becomes largely unnecessary with the Windows Photo Gallery. Well, there are some functions in Picasa2 that I don't see in its Microsoft counterpart but is it really a good enough reason to double the number of indexing services and databases? It might be easier for Microsoft to add the missing functions in an updated version of the Photo Gallery. Because they have been able to reproduce most of Picasa2, I am sure that they can do the rest, too. ;-)

Standard applications include Windows Defender (against spyware), Windows Media Center (a program giving you all the luxury to deal with TV and media as the Media Center Edition of XP), a new Windows Mail (superseding Outlook Express), Windows Calendar, a somewhat modernized Windows Movie Maker, and various accessories that now include a screenshot utility (one that also allows you to cut an arbitrary shape), among other things.

In the right column of the desktop, you usually see widgets - called mini-applications in the Czech edition - and you may add many new ones or remove them.

Security, memory, filters

The integrated security center monitors the health of antivirus and anti-spyware software, the built-in firewall, OS updates, internet settings, and newly introduced warnings against changes of system files (that annoy you whenever you as an administrator do something that could be harmful if you don't know what you're doing or if a nasty worm pretends that she is the boss of your PC). Vista also evaluates the capacity of your computer - taking your processor, memory, hard disk, graphics card, and other things into account.

There are many more settings that determine access rights of various users and groups of users to files and services, new compatibility settings, and other issues. Parental control can be turned on for all accounts.

ReadyBoost is a fun new technology that employs a USB flash card as new RAM. It's cool but I haven't done anything yet that would need such a memory boost. I guess that video editing could be grateful for such a help.

Compatibility

I was able to run a majority of old programs that were copied as directories only: in many cases, one can no longer download the programs and the installation disks are gone so it is an issue. The success list includes a huge portion of old games. I guess that many more games could run if they were properly installed from the scratch, including the automatically created registry entries and license codes.

I am missing drivers for an analog camcorder so far.

The old programs that were running just fine include very old MS-DOS programs except for those that switch to the fullscreen mode in MS-DOS. While Vista still includes some kind of MS-DOS, although it is no longer its core, it doesn't seem to allow this MS-DOS to switch to the fullscreen mode. I view it as a bug that should be fixed. Running old TurboPascal programs with modern fast computers has always been fun and those that were drawing things are mostly gone: the same problem decimates Derive, an MS-DOS ancestor of Mathematica, and other programs. The Commodore64 emulator works fine, including the fullscreen mode.

I recommend you to download DOSbox emulator to run MS-DOS programs of any kind, including full screen mode. You need to "mount" a disk by a command, but then everything works OK.

Independently of Vista, it is cool to run some old graphical games on newer computers. I was immensely impressed by the Mafia game. Everything is fast and smooth even with the most demanding video settings. But Vista clearly can't be credited for this development: it's all about the hardware.

Each new owner of Vista is recommended to download an antivirus program, for example from www.avira.com (free), a faster and more visual defragmenter (Auslogics produces a good free one), Vista Codecs (to deal with DivX-like video codecs that are not included among the standard ones), putty SSH, WinSCP for secure FTP, and many other things.

Jochen Brocks who used to be my roommate when XP was getting started - and we shared our passion for new Microsoft products as opposed to the "dinosaur" Linux et al. despite Jochen's leftist sentiments :-) - warned me that he had some serious crashing problems with Vista. Well, I have only experienced a few application crashes at the beginning and one blue-screen-like crash in an overloaded state - but these problems have probably gone away and didn't materialize after the first day. I guess that with the Internet and updates, most of the reasons behind any potentially wrong behavior will converge to zero quickly.

Summary

I don't think that Vista's improvements are so crucial that an upgrade from XP to Vista would be recommended for most old computers - really old computers are not powerful enough to run Vista anyway - but I am absolutely sure that despite some imperfections, Vista is the best operating system available in 2007 and sane general users without prejudices should clearly make it their operating system of choice for all new computers. There is no reason to wait. That's a rather clear conclusion for which I have to apologize to Ann & Steve Jobs: keep your good work. ;-)

And that's the memo.

Swindle in Australia

After The Great Global Warming Swindle was shown in Britain, Martin Durkin complained that the criticism was too feeble. Well, the global warming believers have re-energized their forces and prepared themselves for the screening by ABC in Australia a week ago or so. The result is that Martin Durkin no longer had to complain that the zealots' attacks were feeble! ;-)

Durkin responds to the Australian critics

I guess that this guy could stand attacks greater by one order of magnitude. ;-)

At any rate, Durkin's critics in Australia must have very tough stomachs, especially because Australia witnessed new record cold temperatures yesterday. They destroyed crops in Queensland. In Czechia, rainy and cold first two weeks of July were followed by two days of marginally record heats but now we have pleasant, average summer temperatures.

Phenomenology of quantum gravity

David Goss has sent me a flawless article from the July 19th issue of Nature, pages 297-301. Everyone who prefers articles about physics itself over fourth-class porn about physicists sleeping with other physicists - the kind of junk that numerous Woits and Smolins offer to their highly undemanding readers - will enjoy it. John Ellis (CERN) explains how powerful the LHC is and why it must see the Higgs-Brout-Englert boson (what an interesting new name!). A picture presents the particle as a rumor about a famous physicist that spreads inside the Higgs ocean, represented by physicists who fill the room.

Ellis is skeptical about technicolor models and analyzes models with extra dimensions and SUSY, motivated by the hierarchy problem. He recalls that string theory, hierarchy problem, LSP as a dark matter candidate, and a precise gauge coupling unification are four independent reasons to take SUSY broken around 1 TeV seriously. Extra dimensions are justified by string theory and the lightest Kaluza-Klein particle (LKP) that may be stable in some models. Their phenomenology includes Kaluza-Klein particles and perhaps small black holes. The LHCb experiment will carefully look at b-quarks and s-quarks and try to find new sources of CP violation i.e. violation of the matter-antimatter symmetry. The penguin diagram is the most specific possibility how this additional violation may be generated and Ellis dedicates a subarticle with this diagram in the middle to the history and facts on CP violation.

He ends up with the prospects to upgrade the LHC if more accurate tests of certain kinds are needed. But let me get to the main topic of this article.

Sabine's musings

I consider Sabine's (and Stefan's) blog to be one of three most inspiring physics blogs in the world. Her openness about various topics is refreshing and it is also helpful that we share certain influences of the Central European cultural space.

However, her opinions about a majority physics questions that go beyond the college material look scarily uninformed to me if not downright dumb.

Her article "Phenomenological quantum gravity" is no exception. I guess that because of political correctness and her sex, no one ever tells her why her constructs are physically nonsensical. At "Loops 2007", there is one more reason why she wasn't told so - namely that all participants except for Moshe Rozali were cranks.

The first oxymoron of the article is its title. No characteristic phenomena based on quantum gravity can be observed today and unless extra dimensions are very large or strongly warped, this situation will continue for quite some time. The assertion in the previous sentence is not a random guess because extra dimensions are necessary to change the dimensional analysis. Every honest person who understands both reality and theoretical physics and who has ever started to study quantum gravity must have known very well that quantum gravity has been a theoretical enterprise.

In fact, today, it is a purely theoretical enterprise. Anyone who is doing quantum gravity and who says that she is doing so by a more physical analysis of experiments than others is cheating herself and the rest of the world, too. It is impossible because no such experiments are available and careful calculations show that in the likely scenarios, they will continue to be out of reach. They have been impossible for those 40 years during which the people were talking about quantum gravity, and frankly speaking, I estimate that they will continue to be impossible at least for next few decades. If someone promises that he or she will surely transform these phenomena into observational science in a foreseeable future is a liar.

Quantum gravity is about doing the theory and mathematics carefully and right. It has never been motivated by easily doable experiments, it is not motivated by them today, and it will probably not be motivated by them in a foreseeable future.

Questions to be answered

At the beginning, Sabine outlines some of the questions that should be answered by the research and they make sense:

But [the Standard Model] has also left us with several unsolved problems, question that can not be answered - that can not even be addressed within the SM. There are the mysterious whys: why three families, three generations, three interactions, three spatial dimensions? Why these interactions, why these masses, and these couplings? There are the cosmological puzzles, there is dark matter and dark energy. And then there is the holy grail of quantum gravity.

If you neglect the subtlety that families and generations are the same thing :-) - she might have mentioned three colors - everything is justifiable and somewhat conventional.

However, you may notice that what she actually writes about later has absolutely nothing to do with any of these big questions about the Standard Model. And I will argue that it has nothing to do with quantum gravity either.

She introduces the top-down and bottom-up approaches. That would be fine except that all of her additions are strange. Let me start with the terminological issues. First, she gives a new name to the top-down approach: she turns it into a "reductionist approach". That's a very bizarre identification. In reality, the particle phenomenologists and model builders are pretty much as staunch believers in reductionism as string theorists. The top-down vs bottom-up dichotomy is not about reductionism. Reductionism is a rational belief that a theoretical tunnel can be built to connect relatively complex perceptions with pure, elementary forms of existence - with fundamental forces and particles. Top-down and bottom-up approaches differ in the strategy how to dig this tunnel. If you wanted to find an approach that questions reductionism, you would have to talk to some condensed matter physicists such as Robert Laughlin who would like to talk about fundamental physics of space but who have no idea what they're talking about.

Principled vs constructivist theories

Sabine's own name for the bottom-up approach is "constructivist approach". That's less inaccurate than the "reductionist approach" but it is still a historically and logically misleading term. Recall that Albert Einstein has divided physical theories to principled and constructivist theories. Principled theories start with a grand principle and then mathematically derive its consequences for our observations. Einstein named thermodynamics (the non-existence of perpetuum mobiles of various kinds being its principles) and both theories of relativity (with its postulates) as examples. On the other hand, constructivist theories, represented by statistical physics or quantum mechanics, build their new insights by grouping several known phenomena and quantitatively abstracting their common features.

Most string theorists surely prefer the first approach even though the actual history of string theory has been a wiggly, phenomenological one. While we understand the theory pretty well these days, we still don't know what is the universal principle behind all of it and whether such a principle exists at all.

You might think that Einstein's principled theories are results of top-down work while the constructivist theories are bottom-up, phenomenological models. However, the adjectives top-down and bottom-up contain something that Einstein couldn't have understood well: the scales. When we talk about top-down and bottom-up things today, we literally talk about the pyramid of energy scales, with the top represented by the huge Planck energy and the bottom represented by the 0.1 TeV scale that is accessible to current experiments. These simple insights about the renormalization group have allowed us to organize our ignorance in a logical and visually satisfactory way. The long-distance physics is pretty much independent of the short-distance details which is both good as well as bad news. It's good because we can learn long-distance physics without knowing the short-distance details. It's bad because of the same reason, namely because we can't directly learn short-distance physics from its long-distance manifestations.

Concerning the "reductionist" approach, Sabine writes that

The difficulty with this approach is that not only one needs that 'promising candidate for the fundamental theory', but most often one also has to come up with a whole new mathematical framework to deal with it.

Well, developing and understanding mathematical frameworks has always been a difficulty for most people. I just wonder when did theoretical physicists started to consider this thing a difficulty, too. Developing new mathematical frameworks has been the most important and most exciting part of theoretical physics at least since the era of Isaac Newton.

Middle-of-nowhere approach

All these things were just details. The real fun starts when Sabine tries to describe what is her own approach: does she prefer top-down over bottom-up? We learn that she can't pronounce "phenomenology" so instead,

I picture myself somewhere in the middle. People have called that 'effective models' or 'test theories'. Others have called it 'cute' or 'nonsense'. I like to call it 'top-down inspired bottom-up approaches'. That is to say, I take some specific features that promising candidates for fundamental theories have, add them to the standard model and examine the phenomenology.

I like to call it nonsense, too.

Whenever we consider new physics, we either believe that it could be real, or we don't believe it could be real. If we believe that it is not real, we shouldn't talk about it. If we believe that it is real, we want to answer more detailed and refined questions about it, in order to make progress. There are two known classes of methods how to do so. One of them is to carefully analyze the internal structure of the new phenomena at their typical scale which is usually inaccessible to existing experiments because it is too high. This is the top-down approach. The other approach, the bottom-up approach, is to study consequences of the new phenomena for physics at accessible scales. Sabine's words clearly sound more like the bottom-up approach than the top-down approach: so what does the extra fog mean?

I think that her bizarre "compromise" of the two approaches is meant to allow one to be more sloppy than phenomenologists in their work but simultaneously pretend to be as fundamental as top-down theorists. In other words, the middle-of-nowhere approach is a systematic algorithm to create confusion. One of the main conceptual results of the last 35 years in theoretical physics has been the renormalization group - especially its insight that our knowledge can be organized according to scales. As far as I can say, if someone claims that there can be a middle-of-nowhere approach, she misunderstands this fundamental insight due to Ken Wilson et al.

Sabine's examples of her middle-of-nowhere approach are extremely diverse in character and require separate discussions.

What does the presence of extra dimensions lead to?

This is of course a fair question but it is a standard one for bottom-up phenomenology, investigated in thousands of papers. The fact that extra dimensions have recently been associated with string theory, a top-down theory, is completely irrelevant. Phenomenologists can study and do study extra dimensions with their own bottom-up tools and logic. As phenomenological models, extra-dimensional models are analyzed much like many other models. The only difference is that one can mention that their starting point may also be justified by a known top-down theory which arguably makes them more appealing and more likely. But this fact doesn't influence the rules of the game and what physics actually does with these models too much.

Presence of a minimal length

The Planck length is surely a minimal length below which the usual intuition about geometry is no longer applicable. This fact - a part of the general lore in the field - has been known for decades. In this sense, the Planck scale is a minimal length. But such a proclamation is extremely vague and can only be used to vaguely derive other vague proclamations. What the statement exactly means and how things start to change when you approach the Planck length is pretty much the whole "meat" of quantum gravity. All papers that have been written as of 2007 and that have argued to have derived something more out of the "minimal length" while avoiding string theory belong to the crackpot category. All of them imagine a kindergarten model of the Planck scale physics - where the length remains a good degree of freedom whose eigenvalues are moreover discrete - that is flagrantly incompatible with numerous fundamental features of this Universe.

In other words, the consequences of such a version of "minimal length" include a violation of the rules of the renormalization group, a conflict with rotational symmetry and Lorentz symmetry, unphysical huge entropy density of the vacuum, the absence of light particles and non-gravitational forces. They contradict pretty much everything in physics and because I have written dozens of articles explaining why all existing "discrete quantum gravity" proponents are crackpots, I don't want to write another one.

I apologize for repeating this important point so many times but if someone only wants to look at "specific features" of some ideas and neglect whether models with these features can be compatible with very basic features of the Universe we live in, she is a crackpot.

Preferred reference frame

If you believe Google, there is only one preferred reference frame in the world and you are just reading it. ;-) According to this preferred reference frame, preferred reference frames can be studied in the bottom-up approach but don't have much justification in any known top-down approach. While there exist ways to break the Lorentz symmetry in string theory, such a breaking can always be viewed as a spontaneous symmetry breaking and this kind of breaking is moreover impossible in all known realistic classes of the string vacua.

In the effective field theory approach, a preferred reference frame - which is equivalent to a Lorentz symmetry breaking that preserves the rotational symmetry - produces additional sets of operators of various dimensions that have been classified years ago. Their coefficients must be small - this adjective is quantified by existing observations - which is why they can be viewed as perturbations and the bottom-up approach can't say much more, except for optimizing methods how the hypothetical terms can be seen most easily. The effects of these new terms only become significant or non-perturbatively large at some much higher energy scales where a top-down theory may be needed anyway.

What I want to say is that the Lorentz symmetry breaking has been studied for decades and surely any person who can't say anything concrete but who claims to "know some new important consequences of a preferred reference frame" has produced pure nonsense. Nothing like that exists and even if it did, it wouldn't be new. Don't forget that theories with preferred reference frames were studied throughout the 19th century. As far as I can say, they became pure anachronisms in 1905 and you shouldn't expect anything valuable ever coming out of this kind of research.

Holographic principle

Sorry, Sabine, but I don't believe that there is any bottom-up analysis of the holographic principle or entropy bounds and their consequences: the holographic principle always belongs to top-down physics. From the bottom-up approach, the Planck area is effectively zero and the entropy bounds say that the entropy is smaller than infinity which is not hard to satisfy. At low energies, you can't really think about doable experiments that would try to violate these bounds. The only way to test the entropy bounds - besides realizing that they are safely satisfied by all known objects - is to do Planck scale experiments. In that regime, you can indirectly test them but then you really probe the full top-down theory.

So far I talked about the entropy bounds. What is the difference between entropy bounds and the holographic principle? The difference is somewhat subtle if any. The holographic principle says not only that the maximum information in a given volume is bounded by its surface area - i.e. a finite-dimensional Hilbert space is adequate - but the full system can also be expressed in terms of degrees of freedom that live on the boundary. You can pretty much say that any theory on a finite-dimensional Hilbert space can be phrased in this way which would lead you to the conclusion that the entropy bounds and the holographic principle are equivalent. However, we usually require the theory on the boundary to be special - local, in fact - which is far more constraining. The holographic principle in this strong, local form is true for AdS-like spaces but it is unlikely that for spaces where the warp factor remains finite at the boundary, the boundary theory could be exactly local.

Consequently, we can't really make the phrase "holographic principle" too precise for finite volumes - and only those are relevant for observations. Operationally, holography for finite volumes is equivalent to entropy bounds that have already been discussed. There's really nothing waiting for us here. It may sound nice to define these "research projects" but be almost sure that any paper written about this realistically observable phenomenology of holography is going to be a stupidity.

Stochastic fluctuations

Sabine asks "whether stochastic fluctuations of the background geometry would have observable consequences". I am not sure whether she means the regular quantum fluctuations or something else. If she means something else - namely classical stochastic fluctuations - then it is nonsense because empty spacetime can't have any such fluctuations because they would require the vacuum entropy density to be nonzero which would be a deadly catastrophe that would, among hundreds of other things, heat up everything to huge temperatures and destroy all interference patterns in all experiments.

If she means the conventional quantum fluctuations of the background geometry, there are many ways to see them. They are, among other things, responsible for the anisotropy of the cosmic microwave background and the primordial structure formation - and perhaps some gravitational waves. Does she talk about these standard cosmological questions? It doesn't look so. Does she talk about the uncertainty of the measurements of distances whose error always exceeds the Planck length, as a simple calculation shows in the four-dimensional case? Be sure you can't measure the length that accurately in practice. At any rate, she seems to be talking about some new insights that resemble the formation of first galaxies and that are equally important but different. Well, such an extraordinary statement about a completely new phenomenon is bound to be either spectacular or, much more likely, insane. But Sabine presents it as everyday physics. Does she understand what she's saying? Have the words lost all of their meaning?

We are told that

These approaches do not claim to be a fundamental theory of their own. Instead, they are simplified scenarios, suitable to examine certain features as to whether their realization would be compatible with reality.

In other words, one is allowed to be superficial and arbitrarily choose whatever "features" she likes.

But such a comment can't define a legitimate approach to science: it defines scientific misconduct. Every scientist - including top-down physicists and bottom-up physicists - may find it useful to be superficial, heuristic, or qualitative at certain points. They may neglect certain features or predictions of a model. But a moment later, someone else may perform a more detailed analysis or check other features. If the results of a more detailed analysis show that the results of the superficial approach were wrong or that the neglected "features" significantly change the conclusions about the validity of a theory, the superficial analysis becomes superseded and irrelevant.

It is not legitimate to be cherry-picking "certain features" when the validity of a model is being tested. One must always consider all features that a model is supposed to be able to explain. This is about the very basic rules of the game. No diversity of approaches is allowed here as long as we talk about science rather than falsification of evidence.

The scientific approach dictates us to study things as accurately and deeply as needed to find the right answers at the required level of confidence. If you follow the insights carefully and sensitively, you are being told not only what the answers could be but also how likely various answers actually are. People may disagree about the probabilities of unknown things but what's more important is that figuring out these probabilities - at least qualitatively - is a part of the scientific method. When one uses it properly, she knows how many details should be looked at before some "big answer" is considered seriously or even established as a fact. The only way how I am able to interpret Sabine's middle-of-nowhere approach is as a call to lower standards how many things are analyzed before big results are announced with a lot of self-confidence.

I can't agree with that. What Sabine wants to do is not a new scientific strategy. It is a rejection of the scientific method itself.

The following comments make it clear that this is what she wants:

These models have their limitations, they are only approximations to a full theory. But to me, in a certain sense physics is the art of approximation. It is the art of figuring out what can be neglected, it is the art of building models, and the art of simplification.

Except that she doesn't seem to know the art at all. Had she known it, she would know that there can't be any middle-of-nowhere approach. One can dig a tunnel from France or from Britain or both but you can't start in the middle.

Whenever a physical theory is an approximation and we realize that certain aspects were neglected, we must understand why the neglected aspects were small: otherwise the approximation breaks down.

For example, we neglect higher-derivative operators in effective field theories because their coefficients are inversely proportional to a positive power of M, a mass scale that is supposed to be huge because the effective theory should be valid up to this large scale.

In top-down theories, we make frequent approximations, too. The most typical approximation assumes that a coupling constant - such as the string coupling - is small. That allows one to trust the results of the leading orders of perturbation theory. Analogously, we can assume that N - e.g. the number of colors - is large i.e. 1/N is small. The approximation from the previous paragraph is, in some sense, a special example of the approximations from this paragraph.

Science and art

But justifying why certain things can be neglected is exactly what Sabine doesn't want to do: she wants to replace justifications by arts. That's how I understand why Sabine chose Karl Popper's bizarre quote that "science may be described as the art of systematic over-simplification". Incidentally, I would say that Popper's philosophy was the art of systematic over-simplification of the scientific method that makes him famous enough among the semi-stupid people while he doesn't make scientists too upset so that they would stop his fame.

Is science an art - an art of approximation? Yes and no. It is an art in the sense that finding the right zeroth approximations, which is one of the most spectacular tasks in science, requires scientists to have special skills, much like artists. However, science differs from arts in one essential aspect: the quality of the scientific art is evaluated by very different methods, namely by a comparison of the artwork with experiments, observations, or calculations based on other experiments or observations.

If someone makes an approximation that seems to be illegitimate because it is not based on any good scientific argument - such as the smallness of couplings, gaps between energy scales, or an approximate symmetry - then you can call it art but I prefer to call it bad science. Laughlin's wavefunction behind the fractional quantum Hall effect was good art and good science, too. But one could only find it by seeing that it predicts some required phenomena that were also observed in many labs. In condensed matter physics, it is not hard to produce a lot of experimental data. Just apply for another one-million-dollars grant. Easily accessible experiments make condensed matter physicists more superficial and they don't usually ask "Why". Why is the wavefunction a good approximation of reality? Condensed matter theorists usually don't have to answer much because the experiments do this work for them.

In quantum gravity, we don't have this luxury to see most of the effects directly but this doesn't allow us to eliminate the step of the judgement and replace it by arts, personal aesthetic preferences, or hateful media campaigns. We must continue to judge the approximations scientifically: the only difference is that the arguments inevitably get more indirect, theoretical, and based on increasingly accurate and abstract mathematics. Any other approach to divide ideas to right and wrong in the absence of direct experiments is unscientific.

Incidentally, I find Popper's statement - that science is the art of systematic over-simplification - kind of dumb because of the last word, too. Over-simplification is, by definition, a simplification that is more severe than what would be optimal for getting the best results. It is a bad thing. A more famous guy, Albert Einstein, has said that science should be as simple as possible but not simpler. You can see that at least at the linguistic level, these two sentences are in flagrant contradiction with one another and you don't have to think twice whether I agree with the philosopher or the physicist.

Quantized gravity

Sabine's text gets ever more unreasonable as she gets closer to more concrete questions. We learn that

To be honest though, we don't even know that gravity is quantized at all.

Well, most crackpots don't know it but we certainly do. By "we", I mean the people who are familiar with the inner workings of quantum mechanics, a well-established theoretical framework of physics. The myth that a classical gravity may be coupled to quantum mechanical matter has been discussed in my text about myths on quantum gravity.

Sabine's "arguments" in favor of the myth are nothing else than the usual foggy unscientific gibberish:

I carefully state we don't 'know' because we've no observational evidence for gravity to be quantized whatsoever.

That's very nice from a person who says that she studies quantum gravity. It is exactly isomorphic situation to a hypothetical person who studies evolutionary biology but who says that we have no observational evidence that life has been evolving during the billions of years because we were not there. It's just breathtakingly silly.

All natural sciences have been learning for many centuries that most of the correct explanations are more indirect and abstract than most of the simple-minded people would prefer. As physics makes further progress, we "see" things ever more indirectly and the required ideas are increasingly abstract. Bigots such as Peter Woit will never understand these basic facts about science but it is very sad that Sabine doesn't understand them either.

Not "seeing" gravitons is certainly not the first time in history when we know about something that can't be seen directly. Many other concepts have been known as real to good scientists long before most people could "see" them directly, including atoms, electrons, positrons, pions, charm quarks; numerous germs and viruses causing diseases; new planets (from their gravitational influence), black holes (from equations of GR); many missing links in evolution, genes responsible for XY, and let me stop. When one looks more carefully than others, he may "see" much more than others do. A forced reduction of science to the lowest common denominators - those Woits who "see" the least - would mean to kill science because science requires just the opposite situation: it is led by those who can "see" the most.

Sabine also writes:

The fact that we don't understand how a quantized field can be coupled to an unquantized gravitational field doesn't mean it's impossible.

She turns the whole situation upside down. Understanding becomes misunderstanding and vice versa. Quite on the contrary, Sabine: we do understand why classical gravity can't be coupled to quantum mechanical matter - for example, the gravitational field around the Schrödinger cat is inevitably found in a linear superposition of two profiles after she's "half-killed" by the decaying nucleus. This is not a speculation but a result of an overwhelmingly tested theory within its domain of validity.

The fact that you don't understand why classical gravity coupled to quantum matter is impossible doesn't mean that it is less impossible than it actually is. More generally, understanding is always more important for science than misunderstanding.

I think that Freeman Dyson's quote about "two separate worlds" is equally unreasonable: however, it is less painful from this eminent scholar because he doesn't present himself as a quantum gravity researcher at the same moment. One can easily see that some of the effects of quantum gravity are surely observable in principle. A Planckian collider that would fit our Universe could do a lot and there exist better ways to look at things. Whether these things are observable in practice is surely secondary for any person who was ever really interested in quantum gravity. If someone only cares about things that can be seen in practice (and quickly), he or she should have baked the bread from the very beginning. Doing quantum gravity for money - while believing that practice is more important than principles - is a form of intellectual prostitution.

I am surprised that both Freeman Dyson as well as the person inside him who studies intelligent plant life near Saturn cares so much more about practice than about the principles.

Sabine continues with a discussion of the inverse problem, the hard task to reconstruct a fundamental theory from the low-energy observations. I think that all details in the text and her graph are partially wrong and confused. For example, take her graph. There's a lot of arrows. Let's assume that they mean "determine". Quantum gravity in the top layer determines three things in the second layer from the top: semiclassical quantum gravity, quantum gravity X,Y,Z (which is probably a recursive feature of the graph), and modifications of general relativity. All of these things are supposed to determine "effective models".

Her list of effective models has nothing to do with what we call quantum gravity. DSR and MDR are unmotivated, confused twists of classical (...) non-gravitational (...) kinematics in the Minkowski space, spacetime foams are incompatible with gravity (and the existence of smooth space). Lorentz violation has nothing to do with gravity and if we are strict, it really contradicts it because by a theory of gravity, we really mean a theory that respects the principles of general relativity and the Lorentz invariance of local physics is one of them (it becomes a part of its gauge symmetry).

Finally, extra dimensions and quintessence should be counted as serious physics but they're not really aspects of quantum gravity per se because the quantum character of space plays no role there. Extra dimensions are about a classical geometric background on which other fields may propagate while quintessence is about an additional scalar field.

So you can see that most of the arrows from the second layer to the third layer are just wrong because the second layer lists three out of dozens of important aspects of quantum gravity (95% of which are apparently completely unknown to Sabine as I will discuss at the very end) while the third layer, the "effective models", has nothing to do with quantum gravity per se. Nevertheless, according to the graph, you can only get from quantum gravity to phenomenology in the bottom layer (astrophysics, cosmology, terrestrial labs) through the layer of effective models. Because all the arrows above are really broken, you can't get there.

What fascinates me about these pictures is their combination of a complete disregard for the key questions of a given field and an extreme eclecticism with which the less important, mutually incompatible aspects and theories are mixed with each other. To "improve" her picture, she wants to include a new, entirely meaningless paper about "macroscopic non-locality" - one that we discussed on this blog - into her graph. Doesn't she realize that this whole structure is a pile of stupidities, broken links, missing key entries, and misunderstanding? I can't believe she doesn't. It's all so incredibly stupid.

Finally, we also learn an interpretation of the history of physics that I can't agree with. Sabine wants the history of quantum gravity to mimic what happened with general relativity. We learn that general relativity was in a certain situation at "the beginning of the last century" and later, it was settled by the light deflection by the Sun. Well, general relativity was written down in 1915, published in its final form in 1916, and the light bending was tested in 1919. There was just a small delay there. But more importantly, the light bending observation was more important for the media than it was for the real science. All good theoretical physicists knew that general relativity was the correct theory of gravity by the end of 1916. Moreover, it seems that the 1919 measurements could have been faked because they couldn't have had the necessary accuracy. Even if they were correct, the theoretical considerations based on the combination of special relativity and the equivalence principle were much stronger an argument in favor of general relativity than the particular expedition.

At any rate, the London Times announced on November 7th, 1919, exactly two years after the not-so-great not-October not-revolution, that the Newtonian ideas were overthrown - and some people care about the London Times more than about scientific arguments.

Sabine also says that it "doesn't matter where one starts" because Heisenberg's and Schrödinger's pictures are equivalent, too. That's nice that two formulations of quantum mechanics are equivalent but it doesn't mean that any two ideas in physics are equivalent. Be sure that more than 3/4 of the entries in the graphs and text are not equivalent to any valuable idea in science or elsewhere and it does matter a lot whether scientists study serious science by using sound scientific arguments, or whether they prefer the art how to mix 50 incoherent ways to leave your lover, as recommended by Sabine Hossenfelder and Paul Simon.

And that's the memo.

P.S. Let me copy a list of items that I consider to be the most representative questions of quantum gravity. Note that even though there is no "string theory" in this list, these questions don't seem to overlap with what Sabine considers to be quantum gravity. Be sure that one of us is extremely confused about completely fundamental issues and it is not your humble correspondent. Your humble correspondent thinks that selling stupid ideas unrelated to quantum gravity (and physics) under the mysteriously exciting brand of "quantum gravity" is a form of parasitism.

• Has the Universe ever been infinitely small?
• Did the concepts of geometry such as the distances actually make sense when the Universe was a newborn baby?
  If they didn’t, how should we generalize the tools of geometry so that they don’t collapse in these extreme conditions?
• In other words, what quantities and new kinds of questions should replace the usual concepts of the geometry of space if we want to probe the very early history of the Cosmos accurately?
• Did the rules of the game simplify near the beginning? Was the newborn Universe similar to a computer in any way? If it were, how did it exactly work?
• When you try to multiply the quantities that described the Cosmos, does it matter how you order the factors? When does the ordering matter and when it doesn’t?
Is it allowed for the Universe to suddenly begin its existence or did the moment of creation violate some laws? Was there any “creation of information” when the Universe got started? If there was, what laws did it obey?
• Is the number of the dimensions of space exactly equal to three? Can it be more or less?
• Can there be some uncertainty about the number of dimensions of space?
• Is it possible to create holes in the Cosmos or to discontinuously change its shape?
• Is there any small chance for an observer inside the black hole to send some information about himself to the people who live outside the black hole even though the general theory of relativity forbids that? Or is the information about the troubled person lost forever? These questions underlie the so-called information loss paradox.
  Where do the black holes store the information about the matter that has created them?
• Can an observer detect that he has just crossed the surface of the black hole – the so-called horizon – or is this question impossible for him to answer, just like the general theory of relativity seems to imply?
• Can a black hole be continuously transformed or melted into an elementary particle and vice versa? How does the transition look like?
• What happens if we collide particles whose total energy – and thus the total mass – is almost enough to produce a black hole but not quite?
• Did the Universe have a well-defined temperature at the beginning? How high was it? Is there a universal upper limit on the temperature? What happens if you approach this limit?
• The special theory of relativity unifies space and time but it still allows us to distinguish space-like and time-like separations between two events. Can this last difference between the space and time – technically called the “signature of spacetime” – be removed?
• Should the distances and times be always real numbers that most of us know or does it make sense to imagine that they are more complicated numbers known as complex numbers? If they can be complex, why do we seem to know real distances and times only?
• Are all types of elementary particles and forces manifestations of a more fundamental, unified type of matter? What is this primordial substance and what kind of mathematics and physics should we learn to understand it really well?
• Can there exist Universes that include the force of gravity but whose repertoire of other elementary forces and particles differs from ours? How many possibilities are there? In other words, how many siblings our Universe has? Are there any numbers that control the character of our Universe that can be continuously adjusted?
• If there are many possibilities how the Universe could a priori look like, is there some explanation why we live in this Universe and not another one?
• Is there a fundamental difference between the past and the future or is the difference a matter of conventions and psychology?

Market of ideas

In this essay, I would like to meditate about the analogies between the markets and the value of ideas in pure science. The musings will be somewhat similar to the text about the depth of ideas but the goal will be more quantitative because we will really try to determine something like a monetary value of ideas, including those without any practical consequences (which is the main reason why the quantification is hard). Such a different goal inevitably brings a different, complementary perspective although some sentiments will overlap with the "deep" article.

Value: subjectivity and objectivity

The actual financial appraisal of an object depends on the person or the persons who make the estimate. You might think that such an estimate will be a purely subjective matter but you shouldn't forget that there are always objective circumstances that significantly influence the way how an individual or a group views the value of a product or the value of an idea. She may have particular needs or goals in mind - influenced both by her anatomy as well as cultural and other traditions - and the products or ideas that are instrumental in satisfying her needs and realizing her goals will be assigned a higher value. People who view a certain product as very valuable are the most likely ones who may buy it.

Nevertheless, it is clear that the value will depend on the subject. Once we accept this fact, the whole discussion could turn into a debate in humanities, a very soft description of the number of people who have various needs and who respect various cultural and other values, together with their time evolution that is primarily controlled by social pressures. It is not surprising that humans who don't think that theoretical physics is valuable at all - and most of them don't - usually think that the value of every individual idea in theoretical physics is low. It is equally unsurprising that crackpots make all sorts of crazy judgements: they may conclude that loop quantum gravity is more valuable than e.g. Matrix theory and they are ready to overwhelm you with thousands of similarly insane conclusions.

In this text, I don't want to analyze what various groups of crazy and stupid people think about various ideas that vastly exceed their abilities to understand the real world. However, you may be puzzled: what else can we study? Well, I will try to describe the methods how an ideal observer determines how valuable various ideas are. The assumption here is that a working mechanism would give the opinions of these semi-ideal observers much greater weight in determining the values, much like skillful speculators on the stock market influence the prices more intensely.

We may doubt whether this task is meaningful at all. Is there something such as an idealized observer? The algorithms to evaluate ideas are ideas themselves. They keep on evolving much like other categories of ideas: the ideal observer keeps on improving, too. The best hope is to describe some relationships between ideas that many people in 2007 don't appreciate even though they should. The list of rules will probably be far from complete but it may be much more comprehensive than some other lists that you could be offered elsewhere.

Why do we care about the value of ideas? Well, if a sponsor of sciences wants to invest 100 million dollars, he should probably decide to fund the field where the investment leads to products of the highest value. Similar decisions are being made by individual thinkers and their managers. Once again, different people will end up with different numbers. But the comments below capture some principles that people should be aware of. Note that this application of the calculated value doesn't care much about the overall normalization of the value of all ideas. You may choose a normalization factor that makes the net value of all ideas produced within a year to be equal to the total investments to science and thinking in the same year.

Players: object and relationships

Thousands of years ago, markets were rather simple. You could have bought or sold an animal, a slave, or a chunk of gold. Each of them had a certain price. At the beginning, you had to exchange things for one another. Eventually, money was introduced. It has allowed the players to buy or sell products whose price is a fractional multiple of a cow. It has also allowed them to decide whether they want to own many cows or the money instead.

The capital was found to be able to generate a new capital. People have realized that it makes sense to borrow money. Others have realized that they may want to lend money to others. Many kinds of direct and indirect ownership of various things and many kinds of contracts materialized in the last centuries and people introduced or learned what are interest rates, taxes, bonds, stocks, options, patents, copyrights, funds, and higher derivatives, among dozens of similar concepts. We may argue that these concepts have become too numerous and complicated and transactions with hot air and tricks have unfortunately become more relevant financially than the actual objects with a value, but let us leave this topic for another essay.

Just like the relationships between assets and money, the relationships between ideas have gotten much more complex, too. Scientific papers have many more relations with each other than they have ever had in the past. They depend on a wide spectrum of work that was done with similar or different methods, under similar or different funding schemes, work that was shared by fewer people or more people. Is it still possible to view an idea as a counterpart of a cow that can be sold?

Well, it's complicated because the ideas are no longer pure objects. Most of them are better visualized as relationships between objects. Ideas don't have to be cows, slaves, or coats: many of them are bridges, trade routes, confidence, trade secrets. Other ideas are bridges in between bridges, methods to use different interest rates along trade routes, algorithms to influence perceived confidence, or wise tricks to exchange trade secrets. We don't want to get too deeply into the world of speculators which is why we will try to avoid their daily life and focus on the pristine universe of pure ideas.

Important aspect: probability of validity of an idea

In this section, I would like to argue that the value of a package of theoretical ideas is essentially proportional to the probability that the package is correct.

Consider two such packages, A and B, whose internal values happen to be equal. But A is one million times more likely to be true than B. If you assume that untrue ideas don't have any value, it is not hard to see that the expectation value of the value of A is one million times higher than the expectation value of the value of B. For example, if you believe me that loop quantum gravity is more than one million times less likely to be true than string theory, then - even if you generously assume that the internal value of loop quantum gravity is comparable to the internal value of string theory - it is completely crazy for the global society, from a quantitative viewpoint, to afford more than one milliresearcher of loop quantum gravity.

You may object that invalid ideas may also have a positive value. I agree and the algorithm above can easily deal with this fact. If an idea has a value even if it is incorrect, you should view such an idea as a conglomerate of two ideas. One of them assumes that the package is true and the other assumes that the package is not true. The total value of the conglomerate is more or less equal to the sum of the two parts. It may a priori be questionable whether an assertion should be presented as "A is true" or "non A is false": there is a symmetry between assertions and their negations. However, the calculation of the value breaks the symmetry. One of the two packages mentioned above leads to a higher value. By definition, the assumptions behind this package are described as "key assumptions being valid" while the assumptions behind the cheaper package are "key assumptions being invalid".

As our knowledge increases, we may refine our estimates of the validity of ideas. Just like the stock price of a bankrupt company converges to zero, the value of an idea that seems increasingly clearly incorrect may converge to zero, too. Ideas, much like operating systems, may also lose value when they are superseded by better ones. The useful content of the older ideas is "recycled" and used in a more complete, more unified, better, new framework. As Murray Gell-Mann says in his commercial for Enron, we have inherited some ideas that are unnecessary. We have to jettison that excess baggage in order to make progress.

Important aspect: internal rigidity of a system of ideas

As we have mentioned above, ideas can often be thought of as bridges. They are relationships between existing objects and concepts in the real world and/or the world of other ideas and theories.

In the real world, bridges should have high enough capacity and they should be robust. If the probability that a bridge collapses under a car exceeded 0.0001% or so, the bridge would be clearly useless. How do you get such numbers? Well, a car is only ready to pay 1 dollar for crossing the bridge. If you assume that the people in the car who are killed cost 1 million dollars, it is not hard to see that the probability of collapse should better be smaller than 0.0001% for the toll to exceed the expectation value of the damages. In reality, we have much higher expectations from a bridge because a very small portion of that 1 dollar above may be viewed as profit while the indirect consequences of the collapse are way bigger than 1 million dollars from that single car. You should really count not only the car but also the material costs of the bridge itself. Once you do so, you shouldn't subtract the mortgage from the 1 dollar toll because it would be double-counting but let's not discuss these details.

Anyway, the message is that the bridges must be solid.

The same conclusion holds for theories that connect objects from the real world with each other or with theoretical concepts. This rigidity is actually the main aspect that determines the internal value of a package of ideas. Mathematicians are the first ones who should understand this conclusion. A proof of a mathematical theorem is a bridge - or a sequence of bridges - that connects the assumptions with the final statement. This sequence must be completely reliable for it to have any significant value for an idealized mathematician. Outside mathematics, even unreliable bridges may have a nonzero value because the requirements are not as strict as they are in mathematics: they follow something like a fuzzy logic. In fact, a quantitative calculation similar to the bridge from the real world that we discussed previously may be applied to figure out what is approximately the critical "probability of failure" above which the theoretical bridge becomes useless or worse. At any rate, it is clear that bridges made out of fog - like the content of virtually any paper by Lee Smolin - don't have any significant value.

Important aspect: relevance for other ideas that have already been rated as valuable

Houses in Manhattan are expensive. Why is it so? Well, it's because they can be used to generate a lot of profit, for example through rents. Why do people pay high rents in Manhattan? Well, it's because they can afford it: there are many ways for them to earn a lot of money in Manhattan. The competition between the people who need to live there or who need offices for their businesses elevates the prices. The value of a house can't be estimated if you don't know the location, the context, or the environment.

Is the same thing true in the case of ideas? You bet.

If one can build a reliable bridge between a new idea and some old ideas whose high importance has already been established, such a fact obviously increases the value of the new idea. How could it be otherwise? The economic considerations are analogous to those in Manhattan.

Let me give you an example. In the media and on the blogosphere, you often read that it "doesn't matter" whether the equations of string theory are relevant for the description of heavy ion physics, confinement, whether one can give a stringy geometric description of other important physical processes such as the Higgs mechanism or the chiral symmetry breaking. Also, you often read that it is irrelevant whether the mathematics behind the theory is tightly connected with portions of mathematics that have been recognized as fundamental such as mirror symmetry, enumerative geometry, and many others.

The people who write these "doesn't matter" things are as sensible as the people who say that houses in Manhattan should cost the same as houses in Montana. More concretely, they are complete nutcases. While it is natural to expect that there exist many more people with a rudimentary understanding of the real estate market than those who understand the basic facts about the working of theoretical physics, I am always flabbergasted whenever these imbeciles such as Peter Woit are being read not only by readers who are expected to be ignorant but even by some people who are paid as professional mathematicians or physicists.

Someone may make huge investments in Vanuatu, assuming that it will become the next Manhattan, but he shouldn't expect that everyone else will buy his noiseless houses for octopi on that island for billions of dollars: other rational people usually realize that his guess is unlikely because Vanuatu is not too connected with other places where land is highly valuable. And as we have explained previously, bridges made out of fog don't count.

The general principle that the price of an object increases when it is connected to other expensive objects may be identified not only in the real estate market, other markets studied by economists, and the market of ideas but it is manifested at many other places, too. This principle underlies Google's PageRank algorithm that determines the importance of web pages on the Internet: a page with incoming links from many other important pages becomes important, too. Similar algorithms have been suggested to measure the importance of scientific papers. If a paper A is cited by another paper B that will become important, it is more relevant than another paper that is cited by an unknown paper C.

It can't be otherwise. However, you might protest that the resulting value may be a consequence of a groupthink and historical coincidences. Couldn't the network of skyscrapers have been built in Montana instead? Well, the location in Montana is not as strategic as one in Manhattan because of rivers and oceans. While you might correctly argue that these characteristics are secondary and one could almost definitely find another equally good place where the New York City could have been built, you should realize that the geographic limitations of the world of mathematical and physical ideas are far more constraining. Extraterrestrial civilizations would probably have to find very similar concepts and theories as our civilization has: for example, they would end up with the same list of simple compact Lie groups. In such a severely constrained virtual world, the value of diverse ideas and bridges is far more objective in character than the real estate market on the East Coast which is why the proximity of ideas is much more important and fundamental than it is in the real world.

Just like the price of houses may increase because of this effect, it may decrease, too. Several thriving Czech towns have become unimportant as soon as a new superhighway that has replaced an older road avoided them. The same thing occurs in the world of ideas. If a package of ideas C has been important partly because of its links to another package D and this other package D turned out to be wrong or unimportant, the value of the package C will decrease, too. Note that this link is not the only feature that decides about the value of C so you should avoid absolutist verdicts. But some influence does exist here. It can't be otherwise.

A technical detail: sharing of the value of an idea, priority, and reusability of ideas

In reality, almost no idea is quite new. Most of them are applications of older ideas, mutated variations of previous ideas, or they are at least inspired by some other ideas. These inclusive relationships should never be forgotten. These relationships are similar to those that were already taken into account in the section about the "expensive neighborhoods". But in this section, we talk about a somewhat different situation, a situation in which a new idea overlaps with certain old ideas so that they shouldn't be quite counted as different entities.

If you use music by Madonna in your new movie, you may be forced to pay her royalties. She effectively owns a part of your movie. Similar situation frequently occurs in the world of thinking. A new discovery E is often so powerful that it allows many similar discoveries to be made much more easily. Needless to say, the author of E may take credit for a part of the newer discoveries. Also, if E is discovered independently by several authors, they share the credit. The higher number of authors you have, the less credit each of them may receive.

A discovery may also be made by several authors who can't quite claim to be independent but they are effectively independent. Christopher Columbus has repeated some of the Vikings' discoveries but in a given context, he was effectively the discoverer of America. In this example, the role of the society is unquestionable because the importance of Columbus' re-discovery would be much lower if it had not allowed the Spaniards, Portuguese, and Englishmen to do what they did. In this text, I am trying to focus on objective measures and avoid appraisals that are social constructs as much as I can.

Ideas and concepts may be used and reused. An idea has often applications in vast areas of the human activity and knowledge. The shares that belong to this idea are distributed over a highly fragmented region of the multi-dimensional space of the human knowledge. But you should always be able to look at this multi-dimensional space from the right angle that reveals the idea as a compact object.

Subtlety: discount rate for ideas

In economics, profit in the far future is less relevant than the same profit that occurs right now. The decrease of importance may be thought of as an exponential one whose rate may be pegged to the interest rate or a similar quantity. Recall that with a 3% discount rate, the perceived value of resources available, lost, or created in 2057 is about four times lower than their present value.

The same discounting obviously works in science, too. A discovery that can be made quickly is more joyful and useful than a discovery that will be made in 2057. At the beginning of the text, we indicated that the "overall value of all new ideas" may be pegged to a percentage of the overall GDP. Assuming a roughly constant world population, this assumption implicitly confirms the expectation that a scientist's salary is going to increase, too. If you need the same number of expected man-hours for a particular discovery D and if the scientists need the same number of man-hours to make it, it is clearly cheaper to make the discovery as soon as possible. However, you should discount the value of the money paid to the future scientists which could cancel the effect. Because of the exponential dependence, small discrepancies in the annual rates may dramatically change the conclusions about anything in 2057. Planning 50 years into the future is a shaky and largely irrational enterprise; even communists only had five-year plans.

The intermediate conclusion we have made - that it doesn't matter when the scientists make the discovery - doesn't yet include the discount rate for the value of the discovery itself. When you include it, it becomes true once again that the discoveries should be made as soon as possible.

That's a likable conclusion except that it is simply impossible to speed up the rate of discoveries too much. Certain discoveries are only made by a certain "top" of the workers in the field. For example, if you decided to increase the number of theoretical physicists ten-fold, the rate of important discoveries would probably not increase much. We may argue that the number of people who work in some subfields is already well above the level where the discovery rate approaches a plateau as a function of the number of people. But this conclusion holds for other human activities - even outside science - too. It especially holds for bureaucracy so scientists certainly have no reason to feel a special guilt.

With a sufficient number of thinkers in a certain field, the expected discovery rate D is pretty much close to its maximum determined by the world population and the distribution curves of various abilities. If you multiply the discovery rate D per person by the average value V of a discovery, the product DV should be close to a universal, field-independent constant in a hypothetical social equilibrium.

Funding: a hypothetical market of generous sponsors

It would be fun to write down more detailed algorithms that evaluate the value of various ideas and discoveries and to run them. You might also imagine that you multiply Mike Lazaridis by 100 and these folks could compete with each other in managing the production of ideas. The result of such a market approach would obviously differ from the opinions of an idealized theorist but it might provide us with a semi-realistic benchmark to quantify how meaningful various investments to scientific fields are and which of them seem much wiser than others.

And that's the memo.

Live free or die hard

We're gonna watch Live Free Or Die Hard with Bruce Willis in a local movie theater. Willis is a favorite actor of mine - not only because he is a right-wing anti-PC atheist who has reasonable opinions about environmentalism:



I loved the movie! "Die Hard 04" is arguably better than 01,02,03. People who enjoy socialist realism might have some problems with the content: Bruce Willis would have died roughly 83 times if his death rate were counted in a more realistic fashion. But this fact makes the movie fun.

Warning: the text below contains spoilers

A former employee of FBI who suffers from a kind of grumpiness decides that America is not even wrong. With a staff of fellow bastards, this admirer of Lenin eventually begins his attack on America on the Independence Day. We gradually learn that the attack focusing mainly on a collapse of all IT technologies has three stages, namely crippling of the security enforcement, financial markets, and finally the general infrastructure.

The very first step he must do is to assassinate roughly eight hackers who contributed some code to his evil software and who know too much. Most of them are dead at a certain moment except for the last one. Let me call him James Blunt because this name is easier to remember: I wonder why those writers and movie makers keep on inventing new names instead of reusing some real ones which would make the plot both more entertaining as well as easier to remember. ;-)

The only exception I know of is Michael Crichton who has used the full character of Mick Crowley, an obnoxious activist-journalist with a small penis, in his latest novel which was a great idea, I think. ;-)

James Blunt is just trying to kiss a young woman - let me call her Petra Němcová - at a campus of Rutgers University, my graduate alma mater, although they chose Camden instead of New Brunswick. She mentions that Blunt is not her boyfriend, in a typically female, ambiguous way. Bruce Willis kicks Blunt out of the car, suggesting that he also loves her and claiming that he is her father - which turns out to be the case later - and he goes home. As a detective for NYPD, he is assigned a task by the FBI - which is mostly clueless throughout the movie - to save the last hacker who happens to be no one else than James Blunt. He visits his apartment. The focus of the Willis-Blunt relationship is abruptly changing and the first shooting insanity is getting started.

After the explosion of the apartment, he drives James Blunt to D.C. However, Peter Woit is already in charge of the traffic lights in the capital. ;-) Because all of them show green color, a day of car accidents follows. Willis saves Blunt's life roughly eight times. During one of the incidents, he runs out of ammo so he must destroy a helicopter by throwing a car on it instead. Meanwhile, the FBI is evacuated because of a fake anthrax threat and all TV stations broadcast a fake collapse of the Capitol, your humble correspondent's favorite building in Washington: the power of the grumpy attacker culminates.

Blunt who understands Woit's mentality but who is not really evil starts to co-operate with Willis. He tells him that it is likely that Woit is going to attack the power grid, namely the hub responsible for the Eastern third of the U.S. They have to get a new car. After they crack into a car by activating its airbag, Blunt calls the airbag service, pretending that his dad is dying in his arms. Indeed, the service woman enables the car after a theater performance by Blunt in which he must recall "his" (the real owner's) name.

The power grid guess is correct. Woit's people are already there when Willis and Blunt arrive. An Asian American feminist collaborator of Woit turns out to be the most formidable foe of Willis because she is tough and she knows kung-fu. After long struggles, Willis manages to throw her into a deep hole and sends her an SUV as a bonus. Everyone is happy that this Bitch PhD is gone, except for Woit who learns about the news from Willis himself and starts to feel even more anxious. ;-)

The last major incident takes place in a huge server facility that backs up all important U.S. financial data. Woit - whose control over the facility is elevated by his insider knowledge - uses Němcová, Willis' daughter who was stuck in an elevator after a blackout, to blackmail the main hero. But we learn that she is pretty similar to her father, after all: for example, later she informs her dad about the number of bastards who are left (five) instead of overwhelming him with emotions and fear which is what her captor wanted. Woit kidnaps both Němcová and Blunt. Willis follows them in a stolen truck but Woit's control over the information channels such as satellites is so comprehensive that he can convince the U.S. military to send airplanes against the "truck preparing for a terrorist attack". That makes Willis' attempts to contact the FBI with the help of a fat hacker whom he met previously and who happens to use the same phone channel #666 as the truck did rather futile. Willis' truck pretty successfully fights against the aircraft, destroying a few bridges and superhighways along the way.

While the truck becomes unusable and the FBI is thus unable to follow Woit and his hostages, Willis gets to the right place in the server facility. After a difficult psychological and physical battle, the villains are eliminated, everyone is happy, the daughter is liberated, Blunt is upgraded from a coward to a man with a certain amount of experience, and both Blunt and Němcová indicate that they have special feelings for one another. Of course, the movie doesn't try to solve what would happen with these two people later. ;-)

All similarities of the characters described above with personalities in the real world may be purely coincidental but in some cases, they don't have to be. :-)

And that's the memo.

Friday, July 13th, 2007

The Reference Frame wishes you good luck on Friday 13th and beyond.

Bloomberg: another idiotic article

Elizabeth Lopatto is the name of the latest breathtaking idiot who was hired to write about theoretical physics for Bloomberg. I am periodically amazed that the newer journalists are always able to exceed the degree of mental breakdown of their predecessors.

This particular lady informs her readers about "bad news for expanding universe". That may sound pretty exciting. When you read her text, you first notice that she is not able to distinguish cosmic inflation from the current and future expansion of the Universe due to the cosmological constant. While it is not clear which theory is supposed to be in trouble according to this madam, it is very clear what is the reason why this theory is in trouble: the reason is a popular book, "Endless Universe", by Steinhardt and Turok.

These journalists demonstrably think that the existence of popular books is what decides about the validity of scientific theories. In reality, there hasn't been a single popular book that has significantly influenced the image of reality as painted by physics. Weinberg's "The First Three Minutes" arguably came closest to this goal: it is an advanced popular book that has made many smart people think about nucleosynthesis seriously.

So we learn that inflation and probably the Big Bang itself is in trouble. In order for her to be "balanced", she also decided to criticize Steinhardt and Turok. But do you know what she criticizes them for? Believe me or not, she criticizes their wild models for their "string dependence", i.e. dependence on string theory.

It's incredibly crazy, especially because of the following three related reasons:

• the reliability and robustness of string theory exceeds the reliability and robustness of Steinhardt's and Turok's models by several orders of magnitude
• in a sharp contradiction with the opinion of Ms Lopatto, the very motivation why possible links of their scenario to string theory are mentioned, vaguely studied, and presented as strong by Steinhardt and Turok is their attempt to increase the credibility of their models while Ms Lopatto apparently thinks that such a link is supposed to diminish the credibility
• in reality, their models don't technically follow from string theory and their ideas are largely independent of string theory

Concerning the first point, she could have asked a physicist to give her a qualified estimate of the probability that various models that appear in her article are correct. She would have found out figures like those on my page about these probabilities: the probability that string theory is a consistent theory of quantum gravity is quantified as 99.999% while the probability that it is the right theory of this Universe is close to 85%. This high percentage is based on a tight network of roughly 20,000 mostly robust papers that show that the conclusions of string theory are largely inevitable because they are more or less unbreakably connected with each other and with all experimentally verified principles underlying the real world.

On the other hand, the same page evaluates the validity of ekpyrotic or cyclic models of the Universe - demonstrated in the 21st century - at 0.1%. This number is small because the arguments behind these models are not robust at all. Instead, they are rather random guesses whose motivation is not clear and that are only studied in dozens of very loosely connected papers.

Criticizing cyclic models of the Universe for relying on string theory is as insane as criticizing theories about Elvis Presley living on the Moon for their reliance on the theory that the Moon is an actual celestial body. It's just completely stupid. We also learn what is the main reason that has led Ms Lopatto to her idiotic musings. The reason was once again incorporated in popular books - in this particular case, we talk about two well-known books by two well-known crackpots, Peter Woit and Lee Smolin.

Concerning the last point, I think that it is obvious that she should have asked a string theorist to see whether the cyclic models follow or can be derived from string theory: neither Steinhardt nor Turok are really qualified to answer this question. She would learn that the answer is No.

The inability of science journalists to distinguish nonsense from science, to realistically estimate the probabilities that certain assertions are correct, and to collect the very basic data that are relevant for their texts is getting worse every day while the willingness of editors to employ journalists who don't have the slightest idea about the topic they write about is increasing every day. And what's worse, no one seems to care.

And that's the memo.

Václav Klaus: Climatologists and economists

In the former Austrian-Hungarian monarchy, church bells were obliged to ring every summer to fight against lightnings and thunderstorms - a practice that was ultimately banned by the enlightened emperor Joseph II. During the first July's Saturday, hundreds of musicians across the world were playing against global warming. Our present goal shouldn't be to ban concerts; instead we should find someone who will explain them the matters.

Although I am already repeating it for the x-th time, it is necessary to mention once again that my point is neither to measure the temperatures nor to question that the current temperatures exceed those between the 1940s and 1970s, a period when people used to think that a new ice age was imminent. A global measurement of the average temperature is a difficult task (due to the limited number of weather stations, asymmetric representation of the land and the oceans, questionable information value of any kind of average, variations of temperatures both in space and time, regardless of the scale, and so on) but there is no good reason for me to join the polemics: meteorologists should debate these matters among themselves.

However, meteorologists have to invite climatologists and other natural scientists to collect arguments and decide whether these phenomena are new, whether we see a change of a trend or a normal fluke that may be a part of a cycle, whether the observed dynamics has a short-term or long-term character, and these questions - at least as far as people such as myself can see from outside - are not settled among natural scientists. On one hand, some people claim that there exists "scientific consensus" that these phenomena are new and unexplainable by natural processes (and therefore man-made) and on the other hand, there are numerous people who are proving that the situation is very different, that the observations can be explained "naturally", and that Man plays a secondary or even negligible role in the current warming trend. 2500 scientists grouped around the IPCC, the U.N.-organized intergovernmental climate panel, defends the former opinion while 4000 scientists signed e.g. under the Heidelberg Appeal claims just the opposite. Whatever the right answer is, there is no consensus about it, and even if there were consensus, it wouldn't be a proof.

These questions are not the cup of tea of economists and representatives of other social sciences. These people ask very different questions (which is why they shouldn't be blamed for not being weather or climate experts). They are asking to what extent a particular phenomenon such as warming will be a problem, what its consequences will be, what will be the costs of adaptation, and perhaps what would be the costs of eliminating the phenomenon altogether. This is not a domain of natural sciences.

Economists primarily know that every problem should be considered in its context and it should be assigned a certain weight or measure. I will demonstrate this rule on a random example. Richard Posner, a well-known Chicago professor whose opinions I usually share, wrote in his article Disaster Insurance (Hoover Digest, 2007 vol. 2) that it was necessary to do something about the climate because higher temperatures would lead to higher sea levels, by about two feet in 100 years (even though it is 0.5 - 1.3 feet according to the latest IPCC report) and that this would require a forced transfer of tens of millions of people (see page 45). At first glance, this looks horrible. It is like moving several Czech Republics from one place to another.

However, if we think for a while and consider these issues in their proper context, we realize that what we talk about is about 0.5 percent of the world population. We should immediately see that every year, much more than 0.5 percent of the world population is moving. But this relocation should occur not within one year but within one century: only one hundredth of the number cited above would be moving every year: five thousandths of a percent of the people of the world! This is a completely negligible number - but we could only see this fact by considering the context.

This example was trivial. Economists are adding other contexts - technological progress, human adaptability, increasing wealth (that moves the mankind further away from the subsistence level, allowing us to treat Nature ever more "generously"). Their main tool to acknowledge this context is to discount the future i.e. to give events the right weight that depends on the moment when they occur. A one-thousand-crown bill is "more" than what it will be in 2017 (even if it remains in the form of a banknote or a constant record in a certain bank account): this is a clear conclusion of theories in economics, any other theories about the real life, as well as common sense. But this principle applies not only to banknotes: what about the quality of my life today vs in 2027? Do I pay the same attention to these two quantities in my decisions? If I were doing so or if we were doing so, we would surely listen to all those people who talk about healthy food and we would behave very differently. Why doesn't a student sufficiently invest into his "human capital" (from his parents' viewpoint)? Is it purely because of his ignorance or stupidity, or is it also important to realize that he prefers his life right now over the rest of his life?

We could give a lot of examples of similar kinds. The magic of discounting, i.e. the appraisal of utility of some present acts for the future, plays a role in all of them. This principle is not an erroneous human myopia (that could be eliminated by better eyeglasses). Instead, it is an aspect of elementary human rationality that economics is based upon.

Economists thus agree - without exceptions - that the discount rate is a key parameter of any public i.e. political decision about the reaction of Man (or, hypothetically, the whole present mankind) to a potential climate change. There is not a slightest difference between them in this respect.

Gary Becker, an economics Nobel prize winner, shows that even if we used a discount rate as low as 3 percent, the consequences of global warming for the utility of mankind in 2057 would "weigh" only one quarter of the impact that the same warming would have on the present generation. For the generation in 2107, it would be one sixteenth. (An Economist Looks at Global Warming, Hoover Digest, 2007 vol. 2, page 51.) Slight changes of the discount rate in either direction are able to do total miracles with these calculations - and exactly these calculations appear in computer simulations of the current popularizers of global warming.

However, serious disagreements exist among various economists regarding their opinions about the correct value of the discount rate. They have thought about this issue for centuries but they usually end up close to one of the two possible extremes. One of them is clearly visible in the well-known Stern report that makes almost no distinction between the current generation and the future ones. The report, in fact, explicitly states the following: "If the future generations exist at all, we assume that they deserve the same amount of ethical attention as the present generation." This sentence obviously assumes a zero discount rate.

The opposite extreme argues that the investments into a fight against climate change reduce other investments and all serious cost-benefit analyses should thus incorporate "expenses for the availability of capital" which is nothing else than the free-market interest rate.

What should we choose? Should we believe the market (and its ethics) or ethics of the prophets of global warming? I would prefer to believe the free market (and its interest rate) more than the elitists from the rich and developed world who want the discount rate to be zero (or almost zero).

The debate about this issue must continue. But this debate is unrelated to measurements of temperatures and it is only marginally related to the causes of these changes.

And that's the memo.

Václav Klaus, Czech president, Mladá fronta DNES, July 11th, 2007

Bonus articles related to global warming on The Reference Frame

• 1934 surpasses 1998 as the warmest U.S. year
• Greenhouse gases and saturation
• C. Monckton & alarm about warming
• Naomi Oreskes & myth about consensus on climate change
• Temperature drove CO2 ppm numbers, not the other way around
• IQ2 US duel: climate realists better than alarmists
• Relationship between the sunspots and clouds
• 2006: a list of inconvenient truths for the alarmists
• 2006: coolest year among last 5

Black holes at the LHC

The Planck length: theoretical background

Lenin used to believe that every electron was a galaxy that contained many smaller electrons that were again galaxies with a lot of even smaller electrons and this hierarchy continued indefinitely.



Even though a similar idea of structure and substructure works well at many longer scales, there are many ways to see that this matryoshka-like picture of the world can't be right at the sub-electron level. For example, in reality, all electrons are exactly indistinguishable, even in principle. This is experimentally seen in various proofs of the antisymmetry of their wavefunctions - for example, via the Pauli exclusion principle that controls the atoms. Any internal structure that is not uniquely determined would make two electrons distinguishable and the Pauli exclusion principle would become impossible.

Another reason why these infinite hierarchies can't exist is quantum gravity itself. It is easy to prove a qualitative conclusion that distances must be longer than the Planck length if they can be interpreted via the usual geometric intuition. At shorter distances, quantum phenomena and new physics strongly influence the behavior of objects and prevent us from understanding them in terms of events that occur at well-defined positions in space. Moreover, geometry can no longer be separated from other kinds of existence. Because the uncertainty principle makes the geometry fluctuate so violently, distances shorter than the Planck scale don't exist in the operational sense of the world.

Alternatively, you may say that the information can't be stored in balls that are smaller than the Planck scale because the number of bits inside such balls would have to be smaller than one bit. Information smaller than one bit is too tiny and doesn't allow you to say "something is here" or "something is not here".

Particle physics used to study the internal architecture of particles at ever shorter length scales by pumping ever greater amounts of energy into the particles. The more energy they have, the closer they can get together and the better resolution your collider - a fancy gigantic microscope - can have.

But this rule according to which the characteristic distance is inversely proportional to the characteristic energy doesn't work forever and cannot work forever. As the energy reaches the Planck energy that is connected with the Planck length and you continue to increase the energy, the experiment will no longer allow you to probe shorter distances. Instead, the collisions will produce ever more massive black holes whose size increases as the mass grows: your resolution will bounce and becomes poor again.

The Planck length is the smallest length scale that can be resolved by any experiment one can think about. More generally, the Planck scale is the ultimate cosmic limit for many other quantities, too. The Planck time is the shortest time you can measure, the Planck density is the maximum density that you should ever talk about, the Planck temperature is the highest temperature you can achieve, and so on.



How big are these Planckian quantities? If you set the universal constants $\hbar, c, G_{Newton}$ equal to one - which is what quantum, relativistic, gravitational adult physicists usually do - the Planck quantities are simply equal to one. In normal units, you can thus write them as appropriate products of powers of $\hbar, c, G_{Newton}$ that have the right units. For example, the usual Planck length is equal to $(G_{Newton}\hbar / c^3)^{1/2}$. Numerically it is about $10^{-35}$ meters. A very short distance.

Planckian transition

So what happens when your colliders reach the Planck energy, normally about $10^{19}$ GeV? If the energy of colliding particles is below the Planck energy, the old-fashioned rules of particle physics work. Higher energies translate to higher frequencies, shorter timescales, and corresponding shorter distances. However, as you reach the Planck energy, what you produce no longer looks like ordinary elementary particles. If your center-of-mass energy is well above the Planck energy, the colliding particles get closer to one another than the Schwarzschild radius if they interact at all which is why they produce a black hole. If you keep on increasing their energy, the resulting black hole will grow in mass and radius.



So how does Nature decide whether you produce a normal particle or a black hole?

Actually, there is no qualitative difference between the two. The transition between elementary particles and black holes is smooth. When the elementary particles are much lighter than the Planck mass, you should talk about them in terms of concepts of particle physics. However, as their energy surpasses the Planck scale, these elementary particles inevitably start to act as microstates of black holes. The heavier they are, the more accurately they can be described by classical general relativity.

The particles whose energy is comparable to the Planck scale are the lightest black holes that deserve the name. These baby black holes have a Planckian radius, mass, and energy. The Hawking process decomposes them into a small number of particles of radiation - a number comparable to one. The Hawking evaporation process makes their lifetime very short - comparable to the Planck time. The Planckian black holes evaporate so quickly that it looks like they are shrinking almost by the speed of light.

Only if black holes are larger, their evaporation slows down. They emit a much larger number of the Hawking thermal particles - a number that grows with the black hole mass as a positive power law - and their lifetime becomes much longer than their radius in Planck units. Black holes that are large but not too large can be described by the classical general relativity and quantum or stringy phenomena add tiny corrections. Note that in both limits - very light objects as well as very heavy objects - we know the right zeroth approximation.

In particular vacua of string theory, all the players in the previous paragraphs become very well-defined objects that obey very clear rules of mathematics. In all realistic or semirealistic vacua of string theory, the qualitative rules above hold. But it is fair to say that even quantum gravity theorists who are not string theorists realize that the general picture of the transition from particles to black holes is valid. We know these things without any direct experiments.

You can listen to Peter Woit, Lee Smolin, and one million of additional crackpots whose net IQ exceeds 60 million points and who complain that any conclusion that relies on the human brain or mathematics can't be trusted - it is not even wrong, they will tell you. The number 60 million seems high but it is certainly not enough to change the conclusion by a millimeter. The laws of physics, mathematics, and logic are unbreakable and the only thing that the crackpots can do against them is to brainwash each other and make idiotic journalists write hundeds of moronic newspaper articles.

Can the Planck be closer?

The Planck energy is very high. It is about 15 orders of magnitude higher than the LHC can squeeze into its colliding particles. That will make an artificial production of black holes - even baby black holes - very difficult. Isn't it possible that the black holes are actually much easier to create?

The answer is that the it may be possible even though it looks unlikely: we estimated the probability that black holes would be produced by the LHC at 0.2 percent. The Planck quantities were calculated by dimensional analysis. The easiest way to change the dimensional analysis is to change the dimension. More precisely, you dismiss the usual Newton's constant as a constant in a bad effective theory and you better switch to the higher-dimensional description that doesn't neglect additional dimensions of space. You thus change the dimension of $G_{Newton}$ because the new constant will appear in Newton's law in a different spacetime dimension, with a different power of the distance. That will force you to compensate its dimension by different powers of $\hbar$ and $c$ in order to get the new Planck length.

If there are additional dimensions of space, the fundamental higher-dimensional Planck scale may be much longer than $10^{-35}$ meters advertised above. If you look at all possibilities - old large dimensions and warped dimensions - you will find out that the fundamental Planck length may be as long as the distances accessible to the LHC, about $10^{-19}$ meters. In other words, the LHC could be able to produce baby black holes as long as it simultaneously brings us evidence for extra dimensions - a necessary pre-requisite for the validity of the dimensional analysis we used.

What happens?

Well, if the LHC has enough energy to produce small black holes - but larger than baby black holes - they will go through spindown; Schwarzschild phase; Planckian phase. During the spindown, the angular momentum is rather quickly reduced by emitting many Hawking particles with the angular momentum preferrentially aligned with the black hole's angular momentum.

This will leave us with a black hole that looks almost like a Schwarzschild black hole. You shouldn't forget that such a black hole has many - about $exp(S)$ - quantum microstates that can be interpreted as elementary particles but that are guaranteed, by consistency of quantum gravity, to obey the laws of general relativity. The Schwarzschild black hole will radiate many Hawking particles in all directions. Such a decay into a large number of products looks like fireworks and its signatures are very different from other models of physics beyond the Standard Model.

As the black hole emits and shrinks, it ends up as a baby black hole that is already indistinguishable from ordinary but heavy elementary particles. Details of the processes depend on the scenario - old large dimensions vs warped dimensions and perhaps other details - and the "ordinary" elementary particles can still organize themselves into new phenomena at different energy scales that look like excited strings, branes, or strings moving in additional dimensions.

The black holes discussed in this article shouldn't be confused with the black holes at RHIC whose character is very different from the kind of black holes that you learn about in courses of general relativity because these RHIC black holes only exist in massively curved spaces and they are consequently equivalent to physics of non-gravitational systems such as QCD.

More details about black holes at the LHC may be found e.g. in:

Dimopoulos + Landsberg (over 400 citations, analysis in the context of old large dimensions)
19 more preprints about black holes at the LHC
Report on a recent talk by Steve Giddings
Man-made black holes and global catastrophes

Enjoy and don't be afraid of a global catastrophe caused by the LHC! ;-)

Al Gore & Live Earth

Posted on 07/07/07 at 07:07:07. See also 06/06/06 06:06:06 and 11/11/11 years after the birth of 11-dimensional M-theory at 11:11:11.

Hundreds of musicians have demonstrated that there is much stronger consensus about global warming among rock musicians than among scientists: all of them want to look like saviors of the world while all of them want to live in the most expensive hotels and mansions and to fly in private jets. All of them may be used as textbook examples of hypocrites.

They should better try to be saviors of modern music because saviors of the world usually cause a lot of troubles if they're morons at the same moment, and sometimes even if they're not.

I am not a fan of this particular kind of music and listening to most of those unknown musicians for hours would be a pain for me. The format and goal of Live Earth was a classical advertisement - attempts to connect show industry with unrelated products - but a good advertisement of this type is 24-seconds-long, not 24-hours-long. (A long chain of these concerts was broadcast by the 2nd program of the Czech public TV station - the weakest among 4 major national TV channels. I suppose that the number of people who watched it was negligible.)

It would be much more pleasant for me to listen to one approved hit - such as "All I wanna to is have some fun with one square of toilet paper" by Sheryl Crow or some songs by Madonna - for many hours.

In some sense, I feel that the event could have had a positive impact - it may return "global warming" its well-deserved status of a fashionable ad supported mainly by people who don't have too much stuff in their skulls and whose ideas don't have a lasting value and by their weird audiences who often live on drugs and whom you don't want to live with or even listen to.

That's why I not only subscribe to Martin Durkin's quote below but I even think that most people whom I call sensible surely agree with it:

I think [the concert is] a combination of hypocrisy and ignorance because the idea of Al Gore and Madonna telling us the world is consuming too much makes the mind boggle. But ignorance because so few people are prepared to actually look at the evidence and there is so much evidence now that flatly contradicts the notion of man-made global warming. I think this is political prejudice rather than science.

We have also learned from organizers of the concert in South Africa that the poor attendance in Johannesburg was caused by global warming, too, because extreme cold weather is always caused by global warming, much like normal weather in the other cities.

Jan Hus: burned at stake in 1415

When I left the U.S., both your humble correspondent as well as America celebrated the Independence Day.

That was no coincidence because the air tickets for all other dates were sold out too early. People apparently think that July 4th is the most likely date for a new large terrorist attack against the U.S. soil. Well, the terrorists think that July 4th is the most attractive day for such an attack but because others know what these terrorists dream about, I feel that July 4th is not such a likely date for a terrorist attack, after all.

There would have been lots of things to write about that have something to do with my transfer to Europe but I personally find blogs filled with similar topics boring. But you may expect that such things will appear later.

When I arrived to Prague, July 5th, it was another holiday: in 863, two orthodox missionaries, Saint Cyril and Methodius, arrived to Great Moravia, an ancient edition of Czechoslovakia, and brought the nation scripture and Christianity translated into a Slavic language. The German Catholic influence from the West has later diminished the religious impact of their visit on Czechoslovakia but the scripture has probably had a more lasting impact.

In order to continue with this holiday rule, July 6th is a Czech national holiday, too. Mr Jan Hus - I chose this name because he is actually referred to as "mistr Jan Hus" - a Czech early protestant - was burned at stake in 1415. He invented diacritics - the accents you find in Czech texts, e.g.

• Žluťoučký kůň úpěl ďábelské ódy.

This is a standardized sentence - "Cutely yellow horse was groaning devilish odes" - with a high concentration of special characters that was chosen to test diacritics and find out what coding system a given file/server uses. Fortunately, the problems with various incompatible trans-ASCII coding systems have mostly disappeared and they haven't influenced me in any way for years. Mr Jan Hus has also discovered that the sum of angles in a triangle is always equal to three. ;-)

Even though Hus was a religious preacher and about 60% of Czechs don't believe in any God, he has been viewed as a national hero for quite some time. Many Czechs associate him with the building of the Czech national self-confidence against Germany. Communists liked him because of many additional reasons, especially because the hussite movement that was promoting Hus' ideas after he was executed was living according to the rules of communism.

(The hussites were both communists and terrorists who were singing majestic songs to defeat their enemies - but let me admit that I am still more proud about them than ashamed of them.)

And many people like myself like Hus because he was fighting against numerous bad moral characteristics of a certain fashionable establishment of his era and especially against the gigantic hypocrisy of the 15th century Catholic Church - hypocrisy that was only surpassed by Al Gore and his Church around 2005.

The religious impact of both Cyril and Methodius as well as Mr Jan Hus was limited - the Czech nation was mostly a Catholic one for centuries before it became one of the two most secular nations in the world - but people like Cyril, Method, and Hus are always needed.

And that's the memo.

LHC: horrible girls from CERN are back

Most readers of this blog don't have to be introduced to

Les Horribles Cernettes,

the horrible girls from CERN, a high-energy rock band whose picture was incidentally the first image on the web and whose music has been played on this blog as background sound for more than a month.



After 6 years of absence, Les Horribles Cernettes (WWW) are back on the planks of the CERN Hardronic Festival. On July 21st, they will rock their fans out at CERN Restaurant 3 (Prevessin), with three new songs adding to their physics inspired repertoire: "Big Bang", "Mr. Higgs" and "Every proton of you". Since the release of "Collider", their classic hit song in 1990, the Cernettes have become the queens of "High Energy Music", a branch of High Energy Physics that many physicists cannot live without. Dear to over 20 thousand physicists worldwide, the girl trio has been featured in world class press, including the New York Times, the Herald Tribune, Wired etc., and has performed at numerous physics related events around Europe, official and not, singing about quarks, detectors, the web, networks, microwaves, and the Large Hadron Collider. In fact the LHC, whose acronym was derived from the band name, became famous as a seating appliance for the singers, before becoming a particle accelerator. The band was in fact photographed while sitting on an LHC dipole, 10 years before being built, in what became the first picture ever published on the web. The Cernettes, in the current line up with Michele, Anne, and Victoria, will sing again with their live band (in more recent appearances they had sung over a recorded base), and promise to rock the place down, as is their standard, and to get absolutely everybody at the festival dancing and shaking madly to their sixties sounding doo-wop rock & roll tunes.

Via Silvano de Gennaro, The LHC Management Office

No axions: PVLAS back to Earth

In March 2006, this blog and other blogs have informed about surprising results of the PVLAS collaboration:

Optical rotation in magnetic field

The polarization plane seemed to be affected by the presence of a magnetic field - an effect that could be explained by the existence of a new light scalar field called the axion.

However, the theoretical details of a model that would explain the observation didn't seem natural at all because they needed convoluted constructions to avoid astrophysical bounds, as Jacques Distler argued and I somewhat more passively agreed. Not surprisingly, we were right: the signal has disappeared:

Preprint
PhysicsWeb

Extraordinary statements - and a claim about a new light particle is always extraordinary - require extraordinary evidence and when honest scientists look for such evidence - a stronger signal - the previous weaker signals usually evaporate and the bombshell theories are falsified. This was no exception.

Thanks to Charles Tye!

Carlos Slim: richest person in the world

It turned out that leaving Harvard wasn't such a horribly bad idea for Bill Gates, after all. He eventually became the richest person in the world.

The same mechanism also implies that completing Harvard wasn't such a terribly good idea either. :-) During the very same month when he received the Harvard degree that he has been dreaming about for decades, Gates became poorer than some Mexicans.



So far it is only one Mexican whose name is Carlos Slim Helú even though his pocket (and belly) is not so slim especially because of the soaring stocks of America Movil [sic] that contribute to his \$67 billion worth. I guess that most readers hear his name for the first time but he is apparently a well-known guy in Latin America.

Update: Mukesh Ambani became the richest guy in October 2007.

Sicko & Moore & commies vs Lauren Turner & Google

A famous filmmaker has decided to teach America how to care about its health.



His "Sicko" apparently defends the idea of a communist healthcare system and uses isolated emotional stories to attack health insurers, health providers, drug companies, and the invisible hand of the market itself. "Sicko" is probably a classical example of communist propaganda which is why various people in Cuba enjoyed it so much.

As a person who has tried both the communist and capitalist healthcare models, I assure you that neither of them is perfect, both of them have advantages as well as disadvantages, but you surely don't want the communist model.

Lauren Turner, a Google's employee, wrote a critique of the movie and recommended the people and organizations that are influenced by Moore's slanderous movie to use Google's services for their defense.

The far left-wing blogosphere got angry. For example, look at the Emerging Earth. They think that Turner should be fired because it seems that she dared to disagree with Google's official opinion. The Emerging Earth explicitly assumes that Google Inc. is obliged to agree with the far left-wing activists - see the last comment - and the website moreover argues that all employees must agree with such an opinion of their company, otherwise they must be fired.

In other words, everyone who thinks that the communist opinions of the Emerging Earth are crap must be permanently unemployed if not jailed. I wonder when it exactly became so normal for so many people to promote Stalinist totalitarian policies such as those at the Emerging Earth.

As a person who has liked the U.S. movies in which bastards are simply shot or otherwise stopped, I wonder why no one gives these disgusting commies over there a proper thrashing for their outrageous proposals. Without such a proper thrashing, be sure that this communist scum will keep on spreading.

And that's the memo.

Climate brainwashing: British public resilient

Despite a massive wave of brainwashing and manipulation by the media, the British public keeps its relatively rational opinions about the climate. Alternatively, if you want to use the jargon of Paul Eco-simpleton or Eccleston for short,

the public is in denial about climate change.

See also the BBC.

56% realized that experts were divided about the causes of climate change while 21% disagreed. 40% realized that the climate was too complex to make forecasts while 38% disagreed.

The discussion about the greenhouse effect continues and approaches 500 comments.

Climate change turned out to be less important than crime, immigration, the NHS, traffic, litter, graffiti, parks, noise, and dogs fouling the sidewalks.

America

Meanwhile, in the U.S., 48% of people think that the country shouldn't sign the Kyoto protocol while less than 35% think that it should.

Russia

Russia has warned against hasty actions on climate change.

Reid Bryson

The 87-year-old (he looks great!) co-founder of American climatology, Reid Bryson, became a target of hysterical eco-Nazis because he is a global warming skeptic. So don't expect that high age will save you from this aggressive movement.

Arnold

The governor of California doesn't have to be such an unlimited green nutcase as he often likes to be seen. Schwarzenegger has terminated a radical alarmist in his climate team, Robert Sawyer, and another one, Catherine Witherspoon, followed.

Via Benny Peiser.

Loop quantum cosmology

Shortcut to the discussion about the greenhouse effect

Many newspapers and magazines including New Scientist, USA Today, and Scientific American have recently promoted new "results" within a framework called loop quantum cosmology. I want to explain why 100% of this stuff is unphysical nonsense but we should find a logical place to start.

What is loop quantum gravity?

It is useful to first understand what is loop quantum gravity. Theoretical physics has been amazingly successful. Its basic theories can be summarized on a sheet of paper and they correctly predict the results of virtually all experiments and phenomena we have ever observed.

However, these theories correspondingly rely on difficult mathematics, they are increasingly abstract, and their mathematical and conceptual structure is not comprehensible to everyone. There is a lot of secret coding behind the sheet of paper from the previous paragraph. In order to understand the cutting-edge picture of the Universe or even extend the reach of the human knowledge, one must master not only quantum mechanics and classical field theories but also path integrals, renormalization, the Higgs mechanism, strong-coupling behavior of gauge theories, and many other subjects whose character is either intuitive, observational, or mathematical.

All really big open problems of current theoretical high-energy physics - such as the cosmological constant problem, the vacuum selection problem, a decent solution to the information puzzle, or the puzzle about the beginning of the Universe - only make sense as long as we consider all known qualitative aspects of our picture of the Universe seriously. We must include matter, too.

For example, the only reason why we would (incorrectly) predict that the cosmological constant should be Planckian (huge) is that there exist other forms of matter that can run in the loops. The only reason why we face the vacuum selection problem is that there exist many types of matter sectors that can be coupled to gravity - and this is true even within string theory although the degeneracy is reduced to a discrete set. Most of the information from the black hole that enters the information puzzle is stored in matter fields which also makes them crucial. And these additional matter fields are important during the Big Bang, too. They are never turned off. The fine-structure constants - the electromagnetic one or its generalizations - at the Planck scale are higher than what they are at low energies.

These facts make it clear that it is impossible to study any big question in theoretical physics without taking all other forces and particles into account: ignoring matter fields in these problems is the same thing as ignoring the problems themselves. Moreover, there exists huge evidence that "pure quantum gravity" without non-gravitational matter fields and without any complicated symmetries of the black hole microstates such as the monster group is simply inconsistent.

All currently known systems of ideas that are able to incorporate all essential ingredients of the contemporary picture of the world - including gauge theories coupled to scalars and fermions as well as gravity described by general relativity - turn out to be tightly connected and non-trivially connected within a mathematical structure that we continue to call string theory even though the term suggests a much more narrow-minded a theory than what string theory actually is today. In fact, it is likely that all mathematically possible systems of ideas that can do so are also parts of this string theory - if it is properly defined - but there exists no proof of such a statement. There cannot even exist such a proof right now especially because we can't even make this statement rigorous: we don't have a full definition of the term "string theory". Our knowledge of this structure is divided to "patches" analogous to patches that make up a manifold.

Oversimplifying physics

Some people find quantum field theories and string theory too complicated and they believe that it is possible to do serious or even "deeper" theoretical physics by ignoring most of the insights of the last 60 years or so. Loop quantum gravity is an example of such an approach. Loop quantum gravity violates every single obvious rule explained above - and many others - because

• it wants to study quantum effects of gravity separately from other forces and forms of matter even though there exists no regime in which they can be decoupled and instead, there exists strong evidence that pure quantum gravity is inevitably inconsistent; the papers that try to discuss matter in loop quantum gravity look like albums of octopi and have clearly no connection with particle physics
  
• it wants to use big words even though spiritually, the theory of loop quantum gravity is as naive as discrete theories of many ancient Greek philosophers such as Democritus; no results found after Democritus influence their thinking in any material way
  
• it neglects effects that clearly can't be neglected, as exemplified below, and makes infinitely many unjustifiable assumptions
• no "good features" of the theory that would indicate the consistency of the theory with reality or the internal consistency of the theory are ever found and no one cares: it is a classical example of a GIGO theory, garbage in, garbage out, because wrong assumptions are simply translated into wrong conclusions without anything interesting or encouraging happening in between; in the absence of observations, it is often important to know that a theory works and gives at least qualitatively meaningful answers - a coherent story - even though it was not a priori guaranteed: such a situation never occurs in loop quantum gravity.
  

Loop quantum gravity starts with the manifestly incorrect assumption that any classical theory must have a quantum counterpart and the only question is how to "add the hats". General relativity is such a beautiful theory that we shouldn't really change it at all, those people think, which is why they try to understand the problem of quantizing gravity along these lines.

How do we know that this assumption is incorrect? Well, classical theories may lead to anomalies that imply that no quantum theory with a given classical limit may exist. More generally, quantization of classical theories often leads to non-renormalizable theories which are no good as a starting point for predictions.

These insights are robust conclusions of a paramount section of theoretical physics, the renormalization group, a theoretical machinery that is important both in high-energy physics as well as condensed-matter physics and other fields.

The proponents of loop quantum gravity realize that adding hats to general relativity is somewhat subtle so loop quantum gravity combines the hats with a field redefinition. All hopes that this step is any useful in removing the problems of quantized general relativity violates another fact about theoretical physics - namely that field redefinitions may make things more transparent and easier to manipulate with but they can never make an inconsistent theory consistent. Indeed, it is obvious that any inconsistency on one side can be mapped to the corresponding inconsistency on the other side as long as a dictionary exists. Also, infinitely many undetermined terms in one language can always be translated to infinitely many undetermined terms in another language.

In loop quantum gravity, the degrees of freedom in the metric tensor are randomly re-expressed in terms of a gauge field. This field redefinition is only legitimate locally on the configuration space; globally, it imposes new periodicities (of the Wilson lines) and corresponding quantization rules for the dual variables (areas) because the field redefinition is not one-to-one. The resulting quantization rules are often mentioned as predictions of this approach to quantum gravity; instead, they are nothing else than a measure of inadequacy of their particular field redefinition. The quantization rules are not derived from any robust assumption: they are an assumption itself because they can be easily shown to be equivalent to the incorrect field redefinition.

Our conclusion that by making this particular field redefinition, one loses any contact with the original theory of gravity, can be seen more explicitly. The resulting discrete theory has no traces of Lorentz invariance - a lethal problem that arises from the discreteness of the areas itself - or other basic principles of modern physics, making it extremely obvious that loop quantum gravity has nothing to do with insights of 20th century physics.

The pathological infinite number of unknown parameters of quantized general relativity have their counterparts in loop quantum gravity, too. The situation is more problematic here because the new infinite-dimensional space doesn't contain a single representative theory that would locally obey the Lorentz symmetry, among other key laws. Having an infinite-dimensional space of theories is clearly not enough for having the correct theory anywhere on the space.

Relation of loop quantum gravity and loop quantum cosmology

The theory of loop quantum gravity constructed above is comprehensible to most schoolboys and even to many journalists: the whole world is made out of vertices and links. This "comprehensibility to masses" is the main reason why these otherwise manifestly unphysical ideas continue to be studied. This whole enterprise is driven by crackpots - those guys from the discussion forums who know how to draw a combinatorial graph and who like to think that once they can do it, they surely understand the secrets of the Universe because gauge theories and renormalization groups are just irrelevant technical details that these "geniuses" may generously ignore.



And it looks cool, doesn't it? Especially if you make "Milde Marketing" do the P.R. for you - apparently the main thing that scientists need these days to defend their theories

There exists no sense in which the extraordinarily strong statement about the structure of spacetime at short distances can be derived from reasonable or robust assumptions and there doesn't exist a single consequence of it that would indicate that this feature of spacetime is desirable i.e. connected with any observation or principle of physics, either directly or indirectly.

The specific discreteness of spacetime - and any discreteness, for that matter - is an extremely unlikely religious belief. A belief that those people don't want to question. They like it so much because it makes their world so simple. Results that confirm this belief are interpreted as successes of loop quantum gravity. You may view these "successes" as consistency checks except that they are qualitative self-consistency checks only - something that theoretical physicists should never find enough in the absence of direct observations. There exists no truly quantitative, exact logical link between the different myths about quantum gravity that the loop quantum gravity believers want to assume.

Another part of the religious belief is the so-called background independence, a notion that the whole loop quantum gravity community completely misunderstands and treats very irrationally. For example, Carlo Rovelli has been unable to understand that propagators such as the graviton propagator can't be background-independent because they encode the second derivative of the action around a particular background. The term "background-independent propagator" is exactly the same oxymoron as "Taylor expansion without any point to expand around" but these guys don't care because the adjective "background-independent" is equivalent to "God" and the spiritual content of this adjective is more important than any logical contradiction.

From gravity to cosmology

You might think that loop quantum cosmology is nothing else than the application of loop quantum gravity to the context of cosmology i.e. that loop quantum cosmology will agree with loop quantum gravity, whatever these words mean. You would be wrong.

While loop quantum gravity is an extremely naive model that clearly doesn't have the capacity to incorporate the basic features of the real world as understood during the last 70 years - matter coupled via gauge fields, obeying the proper rules of renormalization, anomaly cancellation as a non-trivial condition on matter spectrum, black hole thermodynamics (the coefficient of the black hole entropy in loop quantum gravity is wrong, among other things), and many others - the people who work on loop quantum gravity don't find loop quantum gravity naive enough.

So they have invented loop quantum cosmology that is even more naive and oversimplified than loop quantum gravity. Here, you don't try to rewrite a general spacetime geometry (ignoring all other degrees of freedom) in terms of gauge fields. Instead, you only try to rewrite a very special kind of spacetime geometry - a uniform and isotropic FRW cosmology - in easier variables that show similar signs of discreteness of time as the degrees of freedom in loop quantum gravity show discreteness of spacetime.

It is absolutely manifest that you are once again throwing the baby out with the bathwater. Our world is neither uniform nor isotropic and the inhomogeneities clearly become very important at the very beginning of the Universe - e.g. before the inflationary era if there ever was one. Whoever uses the FRW cosmology to study a supertiny Planckian universe lacks a completely basic ability to decide what is the range of validity of various approximations, an ability that is absolutely crucial in physics as well as other sciences. There can't be any question that conclusions based on this preposterous assumption will be scientifically worthless and whether or not they qualitatively agree with the correct answers is a matter of pure coincidence.

Fine, so loop quantum cosmology doesn't even start with loop quantum gravity but with something that is even more naive and more unphysical. These approaches nevertheless share most of the problems - for example, there are also infinitely many undetermined parameters about the dynamics and it seems that not a single point in this infinite-dimensional space of theories describes a theory that would at least qualitatively agree with some features of the known observations. There exists not a single encouraging sign of another type - as we have mentioned, e.g. no consistency check is known. The space of loop quantum gravity cosmologies is an infinite-dimensional dumping ground.

How to be both stupid and ambitious

And now these people take this ancient Greek nonsense and they start to argue that it is relevant for solving big open problems in physics of 2007, without a glimpse of evidence. They randomly construct variations of their discrete models that have a beginning or that have a bounce even though it is manifest that no prediction of the model near the Planck scale can be trusted and no feature of the model can really be predicted anyway because of the infinite number of unknowns.

They also want to argue that these primitive models "explain dark energy". Can these models describe anything that would share any quantitative properties with dark energy? The answer is, of course, a resounding "No". Observations make it clear that dark energy is almost certainly a cosmological constant, with pressure equal to minus energy density. Can you get the right equation of state - the very basic, defining feature of observed dark energy - from any framework such as loop quantum gravity or loop quantum cosmology?

The answer is obviously "No". The reason why "p=-rho" is special is called the Lorentz invariance. This special kind of the stress-energy tensor that is relevant for the cosmological constant is proportional to the metric tensor which is why it doesn't break the Lorentz invariance of local physics. But loop quantum theories have no Lorentz invariance at the Planck scale which is why it is infinitely unlikely that a form of matter should ever have the right equation of state. It almost certainly doesn't. Suggesting that some random objects found in some random primitive discrete models are mapped to some highly abstract features of reality - such as the problems of high-energy physics - is stupid beyond imagination.

This whole approach of loop quantum gravity returns us (or at least them) to the era of early primitive religions. Tens of thousands of years ago, people would also believe irrational links between observable phenomena and mysterious hypothetical portions of deeper reality - such as their gods. They have never had a good reason to believe in these links but they were extremely excited about the grandiose connections they were imagining. Reasons to believe in links proposed by loop quantum gravity are absent, too. If people lose the ability or the right to realize that this whole reasoning is absurd, many more people will be returning to the pre-scientific era every day.

And that's the memo.

Strings 2007: summary

I believe that David Gross' entertaining summary of the conference, "Perspectives", will be the most intriguing piece of "Strings 2007" for most readers here.



Via Strings07.blogspot.com where you can find the remaining talks.

Yes, I have verified that the only talk at "Loops 2007" that was not a meaningless pile of nonsense was a popular talk by Moshe Rozali about the current state of background independence according to string theory.

Please feel free to continue the discussion about the greenhouse effect: the number of comments is still well below 500 right now.