The Story of O2

Banded Iron Formation

There's a really nice article in this week's Science about the history of gaseous oxygen in the earth's atmosphere. Everyone agreed that the earth started out without any gaseous diatomic oxygen. There was some debate about when free oxygen first appeared. Minerals older than 2.4 billion years or so showed no signs of oxidized iron (rust). But some researchers believed there was evidence of atmospheric oxygen even earlier. But now a detailed analysis of atmospheric sulfur chemistry supports the later date for oxygen. So there seems to have been a "Great Oxidation Event" around 2.4 billion years ago in which banded iron formations were laid down around the world. Photosynthetic algae appear at around 2.7 billion years ago and perhaps at that point they were producing enough oxygen to create the iron formations.

In the same issue of Science, there's also an article with evidence that the earth held on to its gaseous hydrogen for longer than previously thought, which would help explain some of the history of early life on the planet.

Neutrinos have Mass!

1987A supernova remnant near the center

Neutrinos are produced in several different ways: natural radioactivity here on earth; nuclear reactors; in copious quantities in the Sun and other stars; in supernovas (Wikipedia SN1987A article); and in the Big Bang (though these have yet to be detected, there's indirect evidence here Neutrino ripples spotted in space). In all cases they are ghostly particles, very hard to detect.

The Super-Kamiokande detector, half-filled with pure water. (Courtesy of the Institute for Cosmic Ray Research, the University of Tokyo.)

They were postulated theoretically by Wolfgang Pauli, but it took many years to actually find them.
For a long time one of the great mysteries of physics was the "Solar Neutrino Problem" - the actual number of neutrinos we could detect from the Sun was about a third of the expected flux. This was finally resolved by oscillations among the three types of neutrinos (hence the 1/3). This seems to imply, theoretically, that neutrinos have mass - which has yet to be measured, though it must be very, very small. Until the oscillations were discovered, it was usually assumed that neutrinos were massless, for both theoretical and experimental reasons.
Here are two "popular" articles by John N. Bahcall of Princeton:
Solar Neutrinos: A Popular Account and Solving the Mystery of the Missing Neutrinos

The three years 2001 to 2003 were the golden years of solar neutrino research. In this period, scientists solved a mystery with which they had been struggling for four decades. The solution turned out to be important for both physics and for astronomy. In this article, I tell the story of those fabulous three years.

Here's a recent, more technical review of Neutrino Physics in general by Boris Kayser.

There are many interesting questions about neutrinos which still need to be answered by new experiments (from Kayser).

1. How many neutrino species are there? Are there sterile neutrinos?
There's already an experiment (LSND) which suggests that there might be more than three types of neutrinos. If there are more than three types then there are combinations which do not even couple to the weak nuclear force - they would only interact via gravity. These are the so-called sterile neutrinos.

2. Are neutrinos their own antiparticles?
Charged particles cannot be their own antiparticle, an antiparticle must have the opposite electric charge. But neutrinos are, naturally, electrically neutral, so it's possible. It could be, however, that there's another conserved quantity the "lepton number". It's not clear whether there is such a quantity, but if there is, there thould be distinct antineutrinos.

3. Do neutrino interactions violate CP (charge/parity conservation)?
Why does the universe seem to be made almost entirely of matter, rather than equal amounts of matter and antimatter? CP violation occurs in quarks, but that doesn't appear to be sufficient to explain the observed matter/antimatter imbalance. Since we are made of matter not antimatter, perhaps neutrino interactions are the reason we exist!

Let us not forget neutrino poetry, by John Updike no less.

Recasting Mermin's multi-player game into the framework of pseudo-telepathy

Preprint by Gilles Brassard, Anne Broadbent, Alain Tapp

Entanglement is perhaps the most non-classical manifestation of quantum mechanics. Among its many interesting applications to information processing, it can be harnessed to reduce the amount of communication required to process a variety of distributed computational tasks. Can it be used to eliminate communication altogether? Even though it cannot serve to signal information between remote parties, there are distributed tasks that can be performed without any need for communication, provided the parties share prior entanglement: this is the realm of pseudo-telepathy.
One of the earliest uses of multi-party entanglement was presented by Mermin in 1990. Here we recast his idea in terms of pseudo-telepathy: we provide a new computer-scientist-friendly analysis of this game. We prove an upper bound on the best possible classical strategy for attempting to play this game, as well as a novel, matching lower bound. This leads us to considerations on how well imperfect quantum-mechanical apparatus must perform in order to exhibit a behaviour that would be classically impossible to explain. Our results include improved bounds that could help vanquish the infamous detection loophole.

In Mermin's game, n players are given a simple task which definitely requires communication in a classical setting. By using quantum techniques (involving the notorious concept of entanglement), the task can be performed without any communication at all - hence the "pseudo-telepathy".

The problem, by the way is very simple. It requires three or more players. Each is given an input bit (0 or 1). They are promised that the total number of input 1's is even. They each then produce an output bit. If the sum of the input bits is divisible by four, there should be an odd number of output 1's. If the sum of the input bits is not divisible by four, the sum of output bits should be divisible by two (an even number of output 1's).

Chi-hwa-seon a film by Im Kwon Taek

The Korean film festival continues with this period piece about the life of the 19th century Korean painter Ohwon. Beautiful photography but a somewhat chaotic story of a chaotic life and times.

By the way, in the shot on the cover of the DVD, I believe the characters are depicted in sexual intercourse. It's very hard to tell what's going on beneath those elaborate Korean costumes!



Chunhyang is another even more beautiful film by the same director.

The Isle, a film by Ki-duk Kim

A beautiful, cruel and disturbing Korean film. Pretty little fishing huts atop small barges are moored on an idyllic lake. The mute female proprietor provides fishing tackle, coffee and sex to visiting fishermen. Serial fish hook abuse ensues.

Redback Spiders

Andrade's web page is fascinating, not to mention that she must be most attractive spider copulation researcher imaginable!

Maydianne C.B. Andrade

Much of my current research involves studies of the sexually cannibalistic Australian redback spider (Latrodectus hasselti), and its close relatives, the black widows (genus Latrodectus). Redback spiders are intriguing because males actively 'encourage' females to cannibalize them while they mate. Unlike most other sexually cannibalistic species (e.g., praying mantids) where males attempt to escape from the female's jaws, redback males actually 'somersault' onto the female's mouthparts during copulation = male sexual sacrifice.

The copulatory somersault

(A) Copulation begins with the male standing on the female's abdomen. Both spiders are facing in the same direction and are 'belly to belly'. The male has two copulatory organs (the palps) that are attached at the anterior-most part of his 'head' (cephalothorax). Copulation begins when one of the palps is inserted into the female's genital opening. In most other black widow spiders, the pair copulates while in this posture.

(B) In redbacks, however, a few seconds after palp insertion, the male, using the palp as a pivot, moves into a 'headstand' posture.

(C) The male then quickly turns through 180 degrees, landing with his 'back' (the dorsal surface of the abdomen), directly above the female's fangs. In most matings, the female begins to extrude digestive enzymes almost immediately. She also pierces the male's abdomen with her fangs and begins to consume him while he is transferring sperm.

There's a video of this on her web site.
A previous spider mating post

Appearance DOES Matter

Which person is more babyfaced?
FROM TODOROV et al.
Perspective in Science.

Take a look at these two snapshots. Which man is more babyfaced? Most viewers would say it's the person on the right. And that's the person who lost a 2004 U.S. congressional election to his more mature-faced and competent-looking opponent. In fact, about 70% of recent U.S. Senate races were accurately predicted based on which candidates looked more competent from a quick glance at their faces. This remarkable effect, reported by Todorov et al. on page 1623 of this issue, likely reflects differences in "babyfacedness". A more babyfaced individual is perceived as less competent than a more mature-faced, but equally attractive, peer of the same age and sex. Although we like to believe that we "don't judge a book by its cover," superficial appearance qualities such as babyfacedness profoundly affect human behavior in the blink of an eye.

Rapid Acidification of the Ocean During the Paleocene-Eocene Thermal Maximum

According to the wikipedia entry "The end of the Paleocene (55.5/54.8 Ma) was marked by one of the most significant periods of global change during the Cenozoic, a sudden global change, the Paleocene-Eocene Thermal Maximum, which upset oceanic and atmospheric circulation and led to the extinction of numerous deep-sea benthic foraminifera and on land, a major turnover in mammals."

report in Science. Summary:

A rapid and large global warming event, the Paleocene-Eocene Thermal Maximum (PETM), raised interior ocean temperatures by 4º to 5ºC around 55 million years ago, a rise not equaled in any single event since then. This warming, whose origin is still debated, was accompanied by a dramatic negative carbon isotopic excursion. One hypothesis is that the release of 2000 gigatons of carbon from the destabilization of methane clathrates on the sea floor account for both the carbon isotopic signal and the temperature increase. Zachos et al. (p. 1611) now show that the carbonate compensation depth (roughly the depth at which calcium carbonate is no longer found in the sediment, because of dissolution during sinking) of the ocean rose by more than 2 kilometers during the PETM, which could have happened only if the amount of CO2 added to the ocean was much more than that which has been estimated in the clathrate scenario. They find that 4000 gigatons of carbon would have been needed, so the release of clathrates alone could not have been the cause of the warming.

Art of Science Competition at Princeton

Driven
Anton Darhuber, Benjamin Fischer and Sandra Troian
Microfluidic Research and Engineering Laboratory, Department of Chemical Engineering
SECOND PRIZE WINNER
This image illustrates evolving dynamical patterns formed during the spreading of a surface-active substance (surfactant) over a thin liquid film on a silicon wafer. After spin-coating of glycerol, small droplets of oleic acid were deposited. The usually slow spreading process was highly accelerated by the surface tension imbalance that triggered a cascade of hydrodynamic instabilities. Such surface-tension driven flow phenomena are believed to be important for the self-cleaning mechanism of the lung as well as pulmonary drug delivery.

gallery page at Princeton.

DNA of Deadbeat Voles May Hint at Why Some Fathers Turn Out to Be Rats

Larry J. Young/Yerkes National Primate Research Center
Prairie voles on gels of their DNA, a possible clue to their home life.

Excellent article in today's New York Times.

Some male prairie voles are devoted fathers and faithful partners, while others are less satisfactory on both counts. The spectrum of behavior is shaped by a genetic mechanism that allows for quick evolutionary changes, two researchers from Emory University report in today's issue of Science.
...
People have the same variability in their DNA, with a control section that comes in at least 17 lengths detected so far, Dr. Young said.
...
The Emory researchers recently noticed that in their prairie vole colony, some fathers spent more time with their pups and some less. They traced the source of this variability to its molecular roots, a variation in the length of the DNA region that controls a certain gene.

This is the gene for the vasopressin receptor, the device used by neurons to respond to vasopressin. Voles with long and short DNA segments had different patterns of vasopressin receptors in their brains, which presumably changed their response to the hormone.

In Voles, a Little Extra DNA Makes for Faithful Mates news article in Science.

Prairie voles are renowned for being faithful mates, but some individuals are more faithful than others. The difference may lie in their so-called junk DNA.

... Elizabeth Hammock and Lawrence Young of Emory University in Atlanta, Georgia, report that fidelity and other social behaviors in male prairie voles seem to depend on the length of a particular genetic sequence in a stretch of DNA between their genes. The longer this repetitive sequence, or microsatellite, the more attentive males were to their female partner and their offspring. Those with shorter microsatellites neglected their mates and pups, at least to some degree.

Although there's no evidence that human infidelity or poor parenting stems from similar variations, Hammock and Young, as well as other researchers, have begun to explore whether microsatellites can account for behavioral differences between people and primates such as chimps and bonobos.

Microsatellite Instability Generates Diversity in Brain and Sociobehavioral Traits: the research article on vole genetics and behaviour in today's Science Magazine.

Here is Young's web page at Emory University

QCD and Natural Philosophy

by Frank Wilczek. This is getting embarrassing! The embarrassment of Wilczek riches continues with this 2002 preprint at the physics archive.

His take on the "Reductionist Program"

The reductionist program, roughly speaking, is to build up the description of Nature from a few laws that govern the behavior of elementary entities, and that can't be derived from anything simpler. This definition is loose at both ends.
On the output side, because in the course of our investigations we find that there are important facts about Nature that we have to give up on predicting. These are what we - after the fact! - come to call contingencies. Three historically important examples of different sorts are the number of planets in the Solar System, the precise moment that a radioactive nucleus will decay, or what the weather will be in Boston a year from today. In each of these cases, the scientific community at first believed that prediction would be possible. And in each case, it was a major advance to realize that there are good fundamental reasons why it is not possible.
On the input side, because it is difficult - perhaps impossible - ever to prove the non-existence of simpler principles. I'll revisit this aspect at the end of the lecture.
Nevertheless, and despite its horrible name, the reductionist program has been and continues to be both inspiring and astoundingly successful. Instead of trying to refine an arbitrary a priori definition of this program, it is more edifying to discuss its best fruits. For beyond question they do succeed to an astonishing extent in "reducing" matter to a few powerful abstract principles and a small number of parameters.

Cosmology

Although it is usually passed over in silence, I think it is very important philosophically, and deserves to be emphasized, that our standard cosmology is radically modest in its predictive ambitions. It consigns almost everything about the world as we find it to contingency. That includes not only the aforementioned question of the number of planets in the Solar System, but more generally every specific fact about every specific object or group of objects in the Universe, apart from a few large-scale statistical regularities. Indeed, specific structures are supposed to evolve from the primordial perturbations, and these are only characterized statistically. In inflationary models these perturbations arise as quantum fluctuations, and their essentially statistical character is a consequence of the laws of quantum mechanics.
This unavoidably suggests the question whether we might find ourselves forced to become even more radically modest. Let us suppose for the sake of argument the best possible case, that we had in hand the fundamental equations of physics. Some of my colleagues think they do, or soon will. Even then we have to face the question of what principle determines the solution of these equations that describes the observed Universe. Let me again suppose for the sake of argument the best possible case, that there is some principle that singles out a unique acceptable solution. Even then there is a question we have to face: If the solution is inhomogeneous, what determines our location within it?

Another rationalization for considering the Anthropic Principle

As we have just discussed, the laws of reductionist physics do not suffice to tell us about the specific properties of the Sun, or of Earth. Indeed, there are many roughly similar but significantly different stars and planets elsewhere in the same Universe. On the other hand, we can aspire to a rational, and even to some extent quantitative, “derivation” of the parameters of the Sun and Earth based on fundamental laws, if we define them not by pointing to them as specific objects – that obviates any derivation – but rather by characterizing broad aspects of their behavior.
In principle any behavior will do, but possibly the most important and certainly the most discussed is their role in supporting the existence of intelligent observers, the so-called anthropic principle. There are many peculiarities of the Sun and Earth that can be explained this way. A crude example is that the mass of the Sun could not be much bigger or much smaller than it actually is because it would burn out too fast or not radiate sufficient energy, respectively.
Now if the Universe as we now know it constitutes, like the Solar System, an inhomogeneity within some larger structure, what might be a sign of it? If the parameters of fundamental physics crucial to life – just the ones we’ve been discussing! – vary from place to place, and most places are uninhabitable, there would be a signature to expect. We should expect to find that some of these parameters appear very peculiar – highly nongeneric – from the point of view of fundamental theory, and that relatively small changes in their values would preclude the existence of intelligent observers. Weinberg has made a case that the value of the cosmological term Lambda fits this description;and I’m inclined to think that ... and several other combinations of the small number of ingredients in our reduced description of matter and astrophysics do too. A fascinating set of questions is suggested here, that deserves careful attention.

The Unreasonable Ineffectiveness of QCD

There some aspects of QCD I find deeply troubling – though I’m not sure if I should!
I find it disturbing that it takes vast computer resources, and careful limiting procedures, to simulate the mass and properties of a proton with decent accuracy. And for real-time dynamics, like scattering, the situation appears pretty hopeless. Nature, of course, gets such results fast and effortlessly. But how, if not through some kind of computation, or a process we can mimic by computation?
Does this suggest that there are much more powerful forms of computation that we might aspire to tap into? Does it connect to the emerging theory of quantum computers? These musings suggest some concrete challenges: Could a quantum computer calculate QCD processes efficiently? Could it defeat the sign problem, that plagues all existing algorithms with dynamical fermions? Could it do real-time dynamics, which is beyond the reach of existing, essentially Euclidean, methods?
Or, failing all that, does it suggest some limitation to the universality of computation?
Deeply related to this is another thing I find disturbing. If you go to a serious mathematics book and study the rigorous construction of the real number system, you will find it is quite hard work and cumbersome. QCD, and for that matter the great bulk of physics starting with classical Newtonian mechanics, has been built on this foundation. In practice, it functions quite smoothly. It would be satisfying, though, to have a “more reduced” description, based on more primitive, essentially discrete structures. Fredkin and recently Wolfram have speculated at length along these lines. I don’t think they’ve got very far, and the difficulties facing such a program are immense. But it’s an interesting issue.

Inventory and Outlook of High Energy Physics

by Frank Wilczek. The list of well-written articles by Wilczek continues with this 2002 preprint at the physics archive.

"No Conclusion"

But all this progress should not mark an end. Rather it allows us to ask – that’s easy enough! – and (more impressive) to take meaningful, concrete stabs at answering some truly awesome questions. Do all the fundamental interactions derive from a single underlying principle? What is the quantum symmetry of space-time? To what extent are the laws of physics uniquely determined? Why is there any (baryonic) matter at all? What makes the dark matter? Why is there so little dark energy, compared to what it “should” be? Why is there so much, compared to everything else in the Universe? These are not merely popularizations or vulgarizations but genuine, if schematic, descriptions of a few of our ongoing explorations.

The Universe is a Strange Place

by Frank Wilczek. Continuing the Wilczek orgy - preprint in the physics archive. This time the subject is cosmology, instead of particle physics. The abstract:

TThis is a broad and in places unconventional overview of the strengths and shortcomings of our standard models of fundamental physics and of cosmology. The emphasis is on ideas that have accessible experimental consequences. It becomes clear that the frontiers of these subjects share much ground in common.

"Cosmology"

..., one set of exogenous parameters in the standard model of cosmology specifies a few average properties of matter, taken over large spatial volumes. These are the densities of ordinary matter (i.e., of baryons), of dark matter, and of dark energy.
We know quite a lot about ordinary matter, of course, and we can detect it at great distances by several methods. It contributes about 3% of the total density.
Concerning dark (actually, transparent) matter we know much less. It has been “seen” only indirectly, through the influence of its gravity on the motion of visible matter. We observe that dark matter exerts very little pressure, and that it contributes about 30% of the total density.
Finally dark (actually, transparent) energy contributes about 67% of the total density. It has a large negative pressure. From the point of view of fundamental physics this dark energy is quite mysterious and disturbing, as I’ll elaborate shortly below.

Cosmic Rays

Perhaps not quite so sharply posed, but still very promising, is the problem of the origin of the highest energy cosmic rays. It remains controversial whether there so many events observed at energies above those where protons or photons could travel cosmological distances that explaining their existence requires us to invoke new fundamental physics. However this plays out, we clearly have a lot to learn about the compositions of these events, their sources, and the acceleration mechanisms.

Is the Universe a Strange Place?

The observed values of the ratios ...[formulas for the cosmological density ratios] are extremely peculiar from the point of view of fundamental physics, as currently understood. Leading ideas from fundamental theory about the origin of dark matter and the origin of baryon number ascribe them to causes that are at best very remotely connected, and existing physical ideas about the dark energy, which are sketchy at best, don’t connect it to either of the others. Yet the ratios are observed to be close to unity. And the fact that these ratios are close to unity is crucial to cosmic ecology; the world would be a very different place if their values were grossly
different from what they are.
Several physicists, among whom S. Weinberg was one of the earliest and remains among the most serious and persistent, have been led to wonder whether it might be useful, or even necessary, to take a different approach, invoking anthropic reasoning. Many physicists view such reasoning as a compromise or even a betrayal of the goal of understanding the world in rational, scientific terms. Certainly, some adherents of the “Anthropic Principle” have overdone it. No such “Principle” can substitute for deep principles like symmetry and locality, which support a vast wealth of practical and theoretical applications, or the algorithmic
description of Nature in general. But I believe there are specific, limited circumstances in which anthropic reasoning is manifestly appropriate and unavoidable.

The highlighted opinion concurs with my own - for whatever that's worth. The Anthropic Principle seems like one of those things which get invoked when you run out of better ideas. That Weinberg and Wilczek, who have had many very good ideas indeed, are driven to this resort seems like a bad sign to me.

A Constructive Critique of the Three Standard Systems

by F. Wilczek. Preprint in the physics archive.
Abstract:

It has become conventional to say that our knowledge of fundamental physical law is summarized in a Standard Model. But this convention lumps together two quite different conceptual structures, and leaves out another. I think it is more accurate and informative to say that our current, working description of fundamental physics is based on three standard conceptual systems. These systems are very different; so different, that it is not inappropriate to call them the Good, the Bad, and the Ugly. They concern, respectively, the coupling of vector gauge particles, gravitons, and Higgs particles. It is quite a remarkable fact, in itself, that every nonlinear interaction we need to summarize our present knowledge of the basic (i.e., irreducible) laws of physics involves one or another of these particles.

More critical remarks on the Standard Model:

Looking critically at the structure of a single standard model family, as displayed in Figure 3, one has no trouble picking out flaws.
The gauge symmetry contains three separate pieces, and the fermion representation contains five separate pieces. While this is an amazingly tight structure, considering the wealth of phenomena described, it clearly fails to achieve the ultimate in simplicity and irreducibility. Let me remind you, in this context, that electroweak “unification” is something of a misnomer. There are still two separate symmetries, and two separate coupling constants, in the electroweak sector of the standard model. It is much more accurate to speak of electroweak “mixing”.
Worst of all, the abelian U(1) symmetry is powerless to quantize its corresponding charges. The hypercharge assignments – indicated in Figure 3 by the numerical subscripts – must be chosen on purely phenomenological grounds. On the face of it, they appear in a rather peculiar pattern. If we are counting continuous parameters, the freedom to choose their values takes us from three to seven (and more, if we restore the families). The electrical neutrality of atoms is a striking and fundamental fact, which has been checked to extraordinary precision, and which is central to our understanding of Nature. In the standard model this fact appears, at a classical level, to require finely tuned hand-adjustment.

Gravity

What makes this very tight, predictive, and elegant theory of quantum gravity “bad” is not that there is any experiment that contradicts it. There isn’t. Nor, I think, is the main problem that this theory cannot supply predictions for totally academic thought experiments about ultrahigh energy behavior. It can’t, but there are more pressing issues, that might have more promise of leading to contact between theory and empirical reality.
A great lesson of the standard model is that what we have been evolved to perceive as empty space is in fact a richly structured medium. It contains symmetry-breaking condensates associated with electroweak superconductivity and spontaneous chiral symmetry breaking in QCD, an effervescence of virtual particles, and probably much more. Since gravity is sensitive to all forms of energy it really ought to see this stuff, even if we don’t. A straightforward estimation suggests that empty space should weigh several orders of magnitude of orders of magnitude (no misprint here!) more than it does. It “should” be much denser than a neutron star, for example. The expected energy of empty space acts like dark energy, with negative pressure, but there’s much too much of it.
To me this discrepancy is the most mysterious fact in all of physical science, the fact with the greatest potential to rock the foundations. We’re obviously missing some major insight here. Given this situation, it’s hard to know what to make of the ridiculously small amount of dark energy that presently dominates the Universe!

The Flavor/Higgs Sector

We know of no deep principle, comparable to gauge symmetry or general covariance, which constrains the values of these couplings tightly. For that reason, it is in this sector where continuous parameters proliferate, into the dozens. Basically, we introduce each observed mass and weak mixing angle as an independent input, which must be determined empirically. The phenomenology is not entirely out of control: the general framework (local relativistic quantum field theory, gauge symmetry, and renormalizability) has significant consequences, and even this part of the standard model makes many non-trivial predictions and is highly over-constrained. ...
Neutrino masses and mixings can be accommodated along similar lines, if we expand the framework slightly. ... The flavor/Higgs sector of fundamental physics is its least satisfactory part. Whether measured by the large number of independent parameters or by the small number of powerful ideas it contains, our theoretical description of this sector does not attain the same level as we’ve reached in the other sectors. This part really does deserve to be called a “model” rather than a “theory”.

Another cute sarcastic remark (somewhat unfairly out of context):

Finally let me mention one redeeming virtue of the Higgs sector. (“Virtue” might be too strong; actually, what I’m about to do is more in the nature of advertising a bug as a feature.)

Longing for the Harmonies

by Frank Wilczek and Betsy Devine.
As I was reading the Wilczek preprints I thought "Wilczek is such a good writer he should do a book for the general public". Well he has, I have it, I've read it, but it was so long ago (1988), unfortunately I have only vague memories, but mildly positive ones.

Yang-Mills Theory In, Beyond, and Behind Observed Reality

by Frank Wilczek, preprint in the physics archive.
Abstract

The character of jets is dominated by the influence of intrinsically nonabelian gauge dynamics. These proven insights into fundamental physics ramify in many directions, and are far from being exhausted. I will discuss three rewarding explorations from my own experience, whose point of departure is the hard Yang-Mills interaction, and whose end is not yet in sight. Given an insight so profound and fruitful as Yang and Mills brought us, it is in order to try to consider its broadest implications, which I attempt at the end.

Wilczek is an excellent writer (see especially his Nobel lecture in the previous post). This article probably isn't quite as accessible to a general audience (as you can probably see from the abstract). The average reader is probably not familiar with "Yang-Mills" theories and the article doesn't try to explain them, but it's still worth a peek, if you can skim past any unfamiliar technicalities.

For example: "But as physicists hungry for answers, we properly regard strict mathematical rigor as a desirable luxury, not an indispensable necessity". Which might surprise non-physicists - mathematicians are often appalled by the pseudo-mathematical activities of theoretical physicists.

Here's another quote along the same lines, this time from "Quantum Theory: Concepts and Methods" by Asher Peres.

Physicists usually have a nonchalant attitude when the number of dimensions is extended to infinity. Optimism is the rule, and every infinite sequence is presumed to be convergent, unless proven guilty.

While a mathematician would probably treat an infinite sequence with extreme suspicion until it was proved to converge.

Our current theories of particle physics are not really viewed as anything more than "low-energy" approximations, they can't even be made to produce sensible answers at higher energies. Here's another quote from the Wilczek article:

A slightly different perspective on renormalizability is associated with the philosophy of effective field theory. According to this philosophy it is presumptuous, or at least unnecessarily committal, to demand that our theories be self-contained up to arbitrarily large energies. So we should not demand that the effect of a high-mass cutoff, which marks the breakdown of our effective theory, can be removed entirely. Instead, we acknowledge that new degrees of freedom may open up at the large mass scale, and we postulate only that these degrees of freedom approximately decouple from low-scale physics. By requiring that the effective theory they leave behind should be self-contained and approximately valid up to the high mass scale, we are then led to a similar "effective" veto, which outlaws quantitatively significant nonrenormalizable couplings.
Of course, this philosophy only puts off the question of consistency, passing that burden on to the higher mass-scale theory. Presumably this regress must end somewhere, either in a fully consistent quantum field theory or in something else (string theory?).

Here's another version on this theme, this time by Steven Weinberg in his 1986 Dirac Memorial Lecture Towards the Final Laws of Physics (which is included in the slim volume Elementary Particles and the Laws of Physics by Richard P. Feynman & Steven Weinberg - Feynman article is also very good).

Most theoretical physicists today have come around to the point of view that the standard model of which we're so proud, the quantum field theory of weak, electromagnetic and strong interactions, is nothing more than a low energy approximation to a much deeper and quite different underlying field theory

The concluding section of Wilczek's article is titled "Patterns of Explanation", it's especially nice:

If there are to be simple explanations for complex phenomena, what form can they take?
One archetype is symmetry. In fundamental physics, especially in the twentieth century, symmetry has been the most powerful and fruitful guiding principle. By tying together the description of physical behavior in many different circumstances – at different places, at different times, viewed at different speeds and, of course, in different gauges! – it allows us to derive a wealth of consequences from our basic hypotheses. When combined with the principles of quantum theory, symmetry imposes very stringent consistency requirements, as we have discussed, leading to tight, predictive theories, of which Yang-Mills theory forms the archetype within the archetype.
(In the present formulation of physics quantum theory itself appears as a set of independent principles, which loosely define a conceptual framework. It is not absurd to hope that in the future these principles will be formulated more strictly, in a way that involves symmetry deeply.)
A different archetype, which pervades biology and cosmology, is the unfolding of a program. Nowadays we are all familiar with the idea that simple computer programs, unfolded deterministically according to primitive rules, can produce fantastically complicated patterns, such as the Mandelbrot set and other fractals; and with the idea that a surprisingly small library of DNA code directs biological development.
These archetypes are not mutually exclusive. ConwayÂ’s Game of Life, for example, uses simple, symmetric, deterministic rules, always and everywhere the same; but it can, operating on simple input, produce extremely complex, yet highly structured output.
In fundamental physics to date, we have mostly got along without having to invoke partial unfolding of earlier, primary simplicity as a separate explanatory principle. In constructing a working model of the physical world, to be sure, we require specification of initial conditions for the fundamental equations. But we have succeeded in paring these initial conditions down to a few parameters describing small departures from space-time homogeneity and thermal equilibrium in the very early universe; and the roles of these two aspects of world-construction, equations and initial conditions, have remained pretty clearly separated. Whether symmetry will continue to expand its explanatory scope, giving rise to laws of such power that their solution is essentially unique, thus minimizing the role of initial conditions; or whether “fundamental” parameters (e.g., quark and lepton masses and mixing angles) in fact depend upon our position within an extended, inhomogeneous Multiverse, so that evolutionary and anthropic considerations will be unavoidable; or whether some deeper synthesis will somehow remove the separation, is a great question for the future.

Asymptotic Freedom: From Paradox to Paradigm

by Frank Wilczek. Lecture on receipt of the 2004 Nobel Prize in Physics.
Preprint at the physics archive.


QCD Lava Lamp (spontaneous quantum fluctuations in the gluon fields)

These pictures make it clear and tangible that the quantum vacuum is a dynamic medium, whose properties and responses largely determine the behavior of matter. ... The masses of hadrons, then, are uniquely associated to tones emitted by the dynamic medium of space when it disturbed in various ways ... We thereby discover, in the reality of masses, an algorithmic, precise Music of the Void. It is a modern embodiment of the ancients’ elusive, mystical “Music of the Spheres”.

Abstract

Asymptotic freedom was developed as a response to two paradoxes: the weirdness of quarks, and in particular their failure to radiate copiously when struck; and the coexistence of special relativity and quantum theory, despite the apparent singularity of quantum field theory. It resolved these paradoxes, and catalyzed the development of several modern paradigms: the hard reality of quarks and gluons, the origin of mass from energy, the simplicity of the early universe, and the power of symmetry as a guide to physical law.

A beautiful (and often very readable) account of one of the most recent (well, 1972) major advances in theoretical physics.

In theoretical physics, paradoxes are good. That’s paradoxical, since a paradox appears to be a contradiction, and contradictions imply serious error. But Nature cannot realize contradictions. When our physical theories lead to paradox we must find a way out. Paradoxes focus our attention, and we think harder.

"Paradox 1: Quarks are Born Free, but Everywhere They are in
Chains"

Powerful interactions ought to be associated with powerful radiation. When the most powerful interaction in nature, the strong interaction, did not obey this rule, it posed a sharp paradox.

"Paradox 2: Special Relativity and Quantum Mechanics Both Work"

The second paradox is more conceptual. Quantum mechanics and special relativity are two great theories of twentieth-century physics. Both are very successful. But these two theories are based on entirely different ideas, which are not easy to reconcile. In particular, special relativity puts space and time on the same footing, but quantum mechanics treats them very differently. This leads to a creative tension, whose resolution has led to three previous Nobel Prizes (and ours is another).

So we had the paradox, that combining quantum mechanics and special relativity seemed to lead inevitably to quantum field theory; but quantum field theory, despite sub-stantial pragmatic success, self-destructed logically due to catastrophic screening.

A picture of particle tracks emerging from the collision of two gold ions at high energy. The resulting fireball and its subsequent expansion recreate, on a small scale and briefly, physical conditions that last occurred during the Big Bang

Video, etc of the Nobel Lecture.


See also An Emptier Emptiness a previous post about another Wilczek article.

Exact Relativistic 'Antigravity' Propulsion

by F. S. Felber

The Schwarzschild solution is used to find the exact relativistic motion of a payload in the gravitational field of a mass moving with constant velocity. At radial approach or recession speeds faster than 3^-1/2 times the speed of light, even a small mass gravitationally repels a payload. At relativistic speeds, a suitable mass can quickly propel a heavy payload from rest nearly to the speed of light with negligible stresses on the payload.

preprint in the physics archive.

I'm clueless but it sounds too cool.

The author's address is:
Physics Division, Starmark, Inc., P. O. Box 270710, San Diego, California 92198
But I couldn't find much about "Starmark" on the web.

Quantum Theory Looks at Time Travel

by Daniel M. Greenberger, Karl Svozil preprint in the physics archive.

We introduce a quantum mechanical model of time travel which includes two figurative beam splitters in order to induce feedback to earlier times. This leads to a unique solution to the paradox where one could kill one's grandfather in that once the future has unfolded, it cannot change the past, and so the past becomes deterministic. On the other hand, looking forwards towards the future is completely probabilistic. This resolves the classical paradox in a philosophically satisfying manner.

By the way, Greenberger is the G in the famous GHZ paper on quantum theory - so he's definitely no amateur.

The paper uses the mathematical formalism of quantum mechanics, but it is very well-written, so it's easy to skip the equations and see what's going on.

As it turns out, the authors feel that time-travel paradoxes are resolved quantum-mechanically as follows: it might be possible to travel into the past, but you still couldn't change any facts about the future.

This of course, is the theme of numerous science fiction works. The first I personally encountered was the Twilight Zone episode "No Time Like the Past" where

Paul Driscoll uses a time machine to try and change three past events: the bombing of Hiroshima, Hitler's rise to power and the sinking of the Lusitania. He fails miserably at all of them, and decides to escape to the past. He picks Homeville, Indiana. After learning from a history book he's brought along that a fire, started by runaway horses, will burn down a school and injure several children. He sees the wagon with the horses, and in trying to convince the owner to unhitch them, he frightens the horses and they start the fire. Driscoll returns to the present, content to leave the past alone.

from Ritterson's Episode Guides: The Twilight Zone

I remember feeling very frustrated watching this as a child!

In Behold the Man Michael Moorcock's 1969 time travel story, the protagonist goes back to see what Jesus was really like. Jesus turns out to be an idiot and Mary is harlot. The protagonist is bitterly disappointed, but his time machine is broken so he's stuck in the past. However he ends up, really despite himself, saying and doing things that give rise to the Legend of Jesus. "Behold the Man", by the way, is Pilate's sarcasm (John 19,5) as he has Jesus paraded before the crowd.


Motherhood takes another beating in the opening pages of An Alien Heat, the first of a fabulously decadent time travel series, also by Michael Moorcock.

There's a very different way of resolving time travel paradoxes spectacularly unfolded in The Man Who Folded Himself by David Gerrold. If you go back in time to strangle your grandfather in his crib, instead of being thwarted (ala the Twilight Zone) or disappearing in a puff of smoke, the result is quite different. You're still there and you have a dead baby in your hands! History now stands as follows: the past is exactly the same as it was until you materialized in your grandfather's nursery. But events now unfold "normally" with you in the room with the dead baby. This is somewhat reminiscent of the "Many Worlds" interpretation of quantum mechanics due to Hugh Everett. A time travel to the past causes history to fork into a new branch, but unfortunately, you the time traveler have no access to the original branch. If you immediately time-traveled "back" to 2005 you'll find that you were never born and that all other influences your grandfather had on his future never happened.

An earlier version of this same approach to time travel paradoxes occurs in Robert Heinlein's "A Door into Summer". As far as I can tell, this is a actually a logically consistent way to avoid all paradoxes. The physics is a different matter.


I loved the time travel machine from George Pal's 1960 film of H.G. Well's The Time Machine

The General in His Labyrinth by Gabriel Garcia Marquez

I was somewhat disappointed by this book, perhaps partly because I'd read several other books by Marquez, including the stupendous One Hundred Years of Solitude (more than once), so my expectations were very high. I borrowed it from a friend on a whim (Lidia actually, whose apartment is jammed with interesting books), when I realized there was a Marquez I hadn't actually read. It's a historical novel about the last weeks of Simon Bolivar, the Liberator of South America, who was a sick and greatly disappointed man at that point, hence it wasn't exactly upbeat. It reminded me of the sections of One Hundred Years which dealt with a fictional general in that novel - I found those parts rather plodding in an otherwise extremely compelling book. Even so, Marquez writes very, very good last sentences - the last sentence of One Hundred Years is the best last sentence in any book I've ever read. The last sentence of The General was also especially good, it actually gave me goose bumps, even though I didn't particularly care for the first however many thousand sentences which came before. The problem is, you really have to read the whole book before the last sentence has its proper impact - cheating and jumping right to the end probably won't work at all! By the way, my other most memorable last sentence was in Sentimental Education - please feel free to leave a comment with your favorite literary finale.


The Liberator - in better days than those depicted in the novel

Beautiful Graphics from this week's Nature

The density distribution of matter in a slice of the computational volume of the Millennium Run model, showing large clusters with densities 1,000 times the mean density of the Universe (yellow); a 'cosmic web' of filamentary structures 10 to 100 times denser than the mean (purple); and the mostly empty regions (black), often called voids, which contain less than 10% of the mean density of the Universe. The white square shows the size of the computational volume for a full hydrodynamic simulation that would use up the same computational resources as the Millennium Run. (Figure courtesy of Volker Springel.)

Cosmology: Digitizing the Universe by Nickolay Y. Gnedin in Nature 435, 572-573 (2 June 2005).

For years, cosmologists have been racing each other to develop ever more sophisticated and realistic models of the evolution of the Universe. The competition has just become considerably stiffer.

Strongest Source of Gravitational Waves?

Stellar tango. These tightly orbiting white dwarfs, doomed to collide, churn space with gravitational waves in this artist's illustration.
CREDIT: NASA GSFC/D. Berry

At the American Astronomical Society meeting now under way in Minneapolis, Tod Strohmayer (NASA/Goddard Space Flight Center) reported on periodic X-ray pulsations from a source known as RX J0806.3+1527. The pulsations, found with the Chandra X-Ray Observatory, agree with earlier, visible-light observations indicating that the source is a pair of white-dwarf stars orbiting each other in a tight binary system. The two collapsed stars are separated by only 80,000 kilometers (50,000 miles, or one-fifth the Earth-Moon distance) and circle each other every 5.36 minutes. No known binary star has a shorter orbital period.

article in Sky and Telescope.

White Dwarfs in a Death Spiral in Science.

Female spiders exploit double-barrelled sperm storage

Redbacks use cannibalism and conniving to select the best mates.


Large female redbacks can collect sperm from more than one mate.
© Maydianne Andrade

Females seem to hold all the cards in this species.
Maydianne Andrade
University of Toronto, Canada

Female redback spiders are not the most sympathetic of lovers: they routinely begin to eat their suitors before they've had a chance to finish mating. And now research shows that their internal anatomy also helps them get one over males, by influencing which mates get to fertilize their eggs.

The female redback has two organs for storing sperm ...
The two sperm sacs help to prevent a male from stealing a mating advantage simply by being the first to court a female ... A male has two sperm-depositing organs, called palps, that correspond to the female's two sperm sacs, although he can use only one palp in a mating session.

A male tends to break off the end of his mating palp inside the female's sperm sac, partly blocking its entrance, the researchers say. "This functions as a plug, a kind of chastity belt," explains Paul Hillyard, curator of arachnids at the Natural History Museum in London.

Having two sperm sacs may therefore give females extra choice over who fathers her young ... If one of the sacs is blocked by a mate, a subsequent partner can still be given the opportunity to deposit his sperm in the other.

article in Nature News

Fertilizer from the stars

Could a gamma-ray burst have provided nutrients for early plants?
article in Nature by Philip Ball.


Twin beams of gamma rays are thought to burst from the supernovae of giant stars. Click here to see the animation.

The explosion of a star in our cosmic neighbourhood may not sound like good news for life on Earth. But a team of US researchers says that just such a catastrophe could have showered our planet with fertilizer that helped plants to colonize the land about 440 million years ago

a previous Gamma-ray burst post

Andromeda's Stellar Sprawl

Big surprise. . The classic starry disk of Andromeda (left, and central red section on right) extends far deeper into space than astronomers thought (yellow and green, right).
CREDIT: NOAO/AURA/NSF (left); R. Ibata et al./Isaac Newton Telescope (right)

The results are convincing but hard to understand, says astronomer Wallace Sargent of Caltech, who was not part of the study. "I find it very impressive, but I didn't expect to see ordered motion so far out," he says. Some unknown influence must settle the orbits and make them persist for billions of years, Sargent says.

article in Science Now

Galactic neighbour gets supersized in Nature News.

Bringing Up Baby a film by Howard Hawks

has finally come out on DVD. A classic screwball comedy starring Cary Grant and Katharine Hepburn and a great way to spend a rainy afternoon. Just to hear Hepburn pronounce the word "can't" is a delight.





Grant is an earnest paleontologist , Hepburn is his far from earnest nemesis. She loses his brontosaurus intercostal clavicle: audio clip

Quantum Weirdness: A Readers Guide

Einstein (and just about everyone else, for that matter) found some aspects of Quantum Mechanics profundly disturbing. Heisenberg's Uncertainty Principle and the probabilistic nature of quantum theory provoked him to the make the famous statement: "God Does Not Play Dice with the Universe". The EPR thought experiment of the 1930's (Einstein was the E), crystalized some of the strange elements of quantum mechanics, which almost (but not quite!) seems to violate relativity - (see however the post below).

Some of the strangeness of quantum mechanics was nicely isolated in Bell's Theorem, proposed in 1964 by John Bell, which seems to indicate there's a fundamental nonlocal nature to reality - according to quantum theory.


The simplest and most straightforward exposition of quantum weirdness I've found is in the article Quantum Mysteries for Anyone reprinted in "Boojums All the Way Through" by David Mermim.


can be downloaded as an ebook. Has a lot of quantum theory mixed in with very well-written biography by a physicist and long-time contributor to the New Yorker magazine.

For the more mathematically minded:

Quantum Theory, Concepts and Methods by Asher Peres, was the most helpful single reference for me.


The Feynman Lectures on Physics: Volume III is a classic.



Quantum Computation and Quantum Information by Isaac L. Chuang, Michael A. Nielsen is a clear exposition of those topics.

Superluminal telecommunication: an observable contradiction between quantum entanglement and relativistic causality

Authors: Ruo Peng Wang

I present a schema for a superluminal telecommunication system based on polarization entangled photon pairs. Binary signals can be transmitted at superluminal speed in this system, if entangled photon pairs can really be produced. The existence of the polarization entangled photon pairs is in direct contradiction to the relativistic causality in this telecommunication system. This contradiction implies the impossibility of generating entangled photon pairs.

preprint in the physics archive

see also Quantum State of Entangled Photon Pairs by the same author.

I show that the photon pairs used in experimental tests of quantum non-locality based on Bell's theorem are not in the entangled quantum state. The correct quantum state of the ``entangled'' photon pairs is suggested. Two experiments for testing this quantum state are proposed.

The author expresses skepticism about quantum entanglement, which is the basis for many of the mind-boggling phenomenon of quantum mechanics. Unfortunately I don't have the background to evaluate his claims.

Quantum Physics from A to Z

Quantum Physics from A to Z in the Physics archive.

"This is a collection of statements gathered on the occasion of the Quantum Physics of Nature meeting in Vienna."

Since philosophers are beginning to discuss the “Zeilinger principle” of quantum physics [1, 2, 3] it appears timely to get a community view on what that might be. The interpretation in question seems to have been developed over a period totalling 60 years to the day and does not only concern quantum mechanics but physics as a whole.

One of the statements attributed to Zeilinger is "Good papers have to be sexy." This is apparently what passes for sexy in the world of quantum information theory.

A Quantum Constraint for the Physical Viability of Classical Traversable Lorentzian Wormholes

Authors: Kamal K. Nandi, Yuan-Zhong Zhang, Nail G. Migranov

The physical viability of classical wormholes can be ascertained by computing if the total volume of exotic matter needed to maintain the wormhole is finite. Using this value as the lower bound to the quantum ANEC integral, we confirm that only Planck size wormholes can be supported by the massless quantum Klein-Gordon field. Some known wormholes seem to be physically unrealistic.

preprint in the physics archive

Note:
The Planck length is the scale at which classical ideas about gravity and space-time cease to be valid, and quantum effects dominate. This is the ‘quantum of length’, the smallest measurement of length with any meaning.

And roughly equal to 1.6 x 10 to the -35 meters or about 10 to the minus 20 times the size of a proton.

Pretty useless, and that's all this paper wants us to have.
This is more like it!

Can't we please have our wormholes?

Volcano of Colima Erupts in Mexico

Smoke and ash from the Colima volcano, on May 25 2005, 430 miles northwest of Mexico City, in what was the largest eruption in 14 years. (Photo: AP)



October 2004 from Volcano of Colima Mexico, photos


Photograph courtesy of Abel Cortes, Colima Volcano Observatory,
University of Colima, November 22, 1998.
Aerial view of Colima Volcano moments after a lava flow on the upper flank of the volcano collapsed; the photograph is tilted slightly (horizon is in upper right). The white plume is rising directly from the summit of the volcano. The tan-colored ash cloud on the volcano's flank (left side in this view) is rising from a pyroclastic flow. The fast-moving pyroclastic flow was caused by the collapse of a thick lava flow that was extruding from the summit area and oozing down the volcano's steep upper cone. When the lava flow collapsed, the hot lava broke apart into fragments ranging in size from boulders to tiny ash particles and swept down the volcano under the influence of gravity to form the pyroclastic flow; the flow reached a maximum distance of 4.5 km from the summit.


More images and information on Colima at Volcano World (Colima)

SI / USGS Weekly Volcanic Activity Report

A Romantic Love Poster

This poster explains Romantic Love (sorry all you poets)

Article in the New York Times: Watching New Love as It Sears the Brain


co-author Helen Fischer
her web site


Casablanca has been called the most romantic film ever ...
but that was before brain scans.

Spitzer Captures Fruits of Massive Stars' Labors

Check out the Spitzer Space Telescope website at Caltech for more information and spectacular images of the massive star Eta Carinae and the surrounding nebula at Spitzer Captures Fruits of Massive Stars' Labors.

For background information on Eta Carinae try this link

Two of my favorite books about stars are both by James B. Kaler,
The Hundred Greatest Stars and Extreme Stars, both of which discuss Eta Carinae.

How Did House Bands Become a Filipino Export? by John Bowe

An very droll article indeed in the New York Times Magazine, May 29, 2005.


Songbird performing at a resort in Danang, Vietnam

Gan's success depends on knowing his clients' taste. In Thailand, the most requested song is ''Hotel California.'' Taiwan is lately cuckoo for the macarena. The Chinese, he said, ''have not gone to the state of loud music. They are still at the state of like the early rock 'n' roll music, 60's music, Petula Clark, Burt Bacharach, evergreens, you know? 'Born Free,' 'Yesterday,' 'Unchained Melody,' 'I Can't Stop Loving You.''' The most commonly requested song in both China and Japan is Sinatra's ''My Way.'' And yet in the Philippines, Gan said, unless you're at an oldies club, audiences only want the current Top 40. ''If you request 'My Way,' you get shot. I'm not kidding. That actually happened.''

Frank's popularity varies among Asian audiences

Nuclear approach may help climate researchers pinpoint volcanic eruptions

Slice of tree showing rings with sample wedge removed.

"There's gold in them thar rings. Tree rings that is, and Penn State researchers are using the Breazeale Nuclear Reactor to measure gold and link the rings to volcanic eruptions."

"When Peter I. Kuniholm, professor of archaeology and dendrochronology and director of the Malcolm and Carolyn Wiener Laboratory for Aegean and Near Eastern Dendrochronology at Cornell, saw which tree rings held the highest gold levels, he quickly recognized that they dated to years of known volcanic eruptions.

Because trees add a ring a year to their trunks, if researchers know the cutting date of a tree or can calibrate the tree's rings against a previously dated tree, researchers can assign each ring accurately to a specific year. By isolated wood from just one ring, neutron activation analysis can measure the gold that the tree took up during that year with parts per billion sensitivity.

Neutron activation analysis uses the neutrons produced by a nuclear reactor to create temporary radioactive isotopes in a sample. Because each isotope has its own gamma radiation signal, the gamma radiation signal strength indicates the amount of that element present. "

"The preliminary results of analysis of one tree for the years 1411 through 1988 were presented in a recent issue of the Journal of Radioanalytical and Nuclear Chemistry.

Working with Kuniholm and John J. Chiment, another researcher at the dendrochronology laboratory, and Corrnell undergraduate students Pam Sullivan, Meg Underwood and Danielle Hauck, Unlu analyzed 577 rings from a Bosnian or palebark pine from Greece.

"We are looking at the last 500 to 600 years to gain confidence in the procedure," says Unlu. "The volcanic eruptions during that time are known, so we can make correlations. Then we will go back and look at the past 6,000 years."

Six thousand years into the past is the depth of the samples currently at Cornell's dendrochronology laboratory. The lab has already dated approximately 4.5 million tree rings to this time.

The researchers found that they successfully matched gold peaks to volcanic eruptions beginning with an eruption of the Soufriere Hills volcano in 1440 and including a 1480 eruption of Mt. St. Helens. However, the researchers also had high gold peaks for a number of years between 1480 and 1580 when there were no known volcanic eruptions.

"When we see major gold peaks but no volcanoes, it could be forest fires," says Unlu. "We cannot really tell if we are seeing a global signal or a regional or local signal when we are looking at only one tree."

How can a forest fire be confused with a major volcanic eruption? If the researchers are correct, easily. Unlu believes that the increased gold uptake during volcano years occurs because the volcanoes put large amounts of particulate matter into the atmosphere and change the environmental acidity as well as the rainfall, sunshine and temperature patterns creating a stressful situation for trees. The trees, to compensate for a lousy year, try to take up more nutrients, including copper, an essential element for tree growth and health. The gold is indiscriminately absorbed along with the copper, but the copper is used for tree metabolism while the gold remains in the new growth.

Another possible cause of the increased gold uptake could be through the leaves because of direct fallout from the volcanic eruptions, but Unlu believes it is the darkness and stress that push the trees to search for copper among other elements. To eliminate forest fires and other local events, the researchers want to look at other trees from other areas. They are currently looking at two dated trees from Turkey and one from California.

"The main problem in atmospheric science is they do not have enough data," says Hauck, now a graduate student in nuclear engineering at Penn State. "We want to correlate tree ring data with climate cycles to get a much better indication of what is natural and what is anthropogenic. Tree rings can help."

Large volcanic eruptions put particles into the wind, into the jet stream and have a global, rather than only local effect. Unlu would also like to go back and check the samples with high gold for other elements. Because neutron activation analysis is nondestructive, and the samples are no longer radioactive after about a month, this reanalysis for other elements is possible. Unlu now has a Nuclear Engineering Education and Research grant from the U.S. Department of Energy to continue his analysis of tree rings and correlation to volcanic activity and other climate events.
"

The original news release at Penn State University.

A Sensational Title

Carrying on with the theme of A Sensational Title coupled with quite serious research and scholarship, here are three titles for your consideration: Demonic Males; Sperm Wars; Women, Fire and Dangerous Things.

Demonic Males: Apes and the Origins of Human Violence is by Richard Wrangham and Dale Petersen. I first learned about the book after attending a performance of a George Bernard Shaw play at the ART in Harvard Square and sitting in on a subsequent panel discussion. Richard Wrangham was on the panel - he talked about his book, showed slides from his field research with Bonobos (a relative of chimpanzees) and even managed to somewhat tie it in with GBS. Bonobos are known as possibly the sexiest animals on earth and the slides didn't shy away from that fact. The next person on the panel commented that there was an old saying in theater, "never go on after children or animal acts" and it was true, the rest of the panel was at a serious disadvantage after Wrangham's spectacular presentation.

Sperm Wars: The Science of Sexby Robin Baker, combines research published in the most prestigious journals (by the author) with illustrative little scenarios that read like hard-core pornography. An "I buy Playboy/girl for the articles" kind of win-win.

Women, Fire and Dangerous Things: What Categories Reveal about the Mind by George Lakoff, is a quite serious work of Cognitive Science and Linguistics. Evidently there's a language (Australian?) with a grammar which groups the three categories of the title.

"Middlemarch" a BBC production

One of the greatest books ever written leaps to life in this lavishly filmed BBC production, seen on Masterpiece Theatre. You’ll share the frustrations of George Eliot’s heroine (Dorothea Brooke, portrayed by a luminous Juliet Aubrey) whose desire to add meaning to her life conflicts with 19th-century provincial English culture. A turbulent, romantic epic shot on location in England and Italy.

My second favorite BBC series, exceeded only by the incomparable "I Claudius". Unfortunately, there was something wrong with the image, possbily due to my $40 Radio Shack DVD player (you get what you pay for, it seems). The image was stretched vertically and possbily chopped, which rendered the gentlemen's already tall black hats as monstrosities. Still it was a great production - I greedily finished the final three episodes in one sitting, last night.

Cooperate or Else!

"Go ahead, make my day." Dirty Harry succinctly informs a norm violator that he anticipates deriving satisfaction from inflicting altruistic punishment.
CREDIT: WARNER/MALPASO/THE KOBAL COLLECTION

Why exactly do people - and other animals as well - so often cooperate instead of pursuing their individual goals independently, especially in circumstances when there are opportunities for short-term gain by cheating? "It's better to be nice", "For the Good of the Group", and other such sentiments are all well and good, but why isn't altruistic behaviour "selected against" in a world ruled by evolution and the survival of the fittest? Natural selection works directly on individuals, but only indirectly on groups, so group selection is rather tricky in practice.

There have been several interesting new papers in the past year on the role of punishment in maintaining cooperative behaviour: from evolutionary, game-theoretic and neurobiological perspectives.


First a trio of classic books touching on the subject of cooperative behaviour:

The Evolution of Cooperation by Robert Axelrod. The Prisoner's Dilemma, Tit for Tat.

The Selfish Gene by Richard Dawkins. Kin Selection.

Sociobiology by E.O. Wilson. The Magnum Opus.

Next a newspaper article on one of the colorful pioneers of the evolutionary theory of behaviour, Robert Trivers.
Boston Globe (March 27, 2005)

While researching Trivers I stumbled across a wonderful blog by a very attractive thinker Teardrop Souffle.


From an economic, game theoretic point of view, the article that introduced "The Paradox of the Commons":

The Tragedy of the Commons
by Garrett Hardin
Science (13 December 1968)
"In economic affairs, The Wealth of Nations (1776) popularized the "invisible hand," the idea that an individual who "intends only his own gain," is, as it were, "led by an invisible hand to promote . . . the public interest" (5). Adam Smith did not assert that this was invariably true, and perhaps neither did any of his followers. But he contributed to a dominant tendency of thought that has ever since interfered with positive action based on rational analysis, namely, the tendency to assume that decisions reached individually will, in fact, be the best decisions for an entire society"

The rebuttal to the invisible hand in population control is to be found in a scenario first sketched in a little-known pamphlet (6) in 1833 by a mathematical amateur named William Forster Lloyd (1794-1852).

The tragedy of the commons develops in this way. Picture a pasture open to all. It is to be expected that each herdsman will try to keep as many cattle as possible on the commons. Such an arrangement may work reasonably satisfactorily for centuries because tribal wars, poaching, and disease keep the numbers of both man and beast well below the carrying capacity of the land. Finally, however, comes the day of reckoning, that is, the day when the long-desired goal of social stability becomes a reality. At this point, the inherent logic of the commons remorselessly generates tragedy.

As a rational being, each herdsman seeks to maximize his gain. Explicitly or implicitly, more or less consciously, he asks, "What is the utility to me of adding one more animal to my herd?" This utility has one negative and one positive component.

1) The positive component is a function of the increment of one animal. Since the herdsman receives all the proceeds from the sale of the additional animal, the positive utility is nearly +1.

2) The negative component is a function of the additional overgrazing created by one more animal. Since, however, the effects of overgrazing are shared by all the herdsmen, the negative utility for any particular decision-making herdsman is only a fraction of 1.

Adding together the component partial utilities, the rational herdsman concludes that the only sensible course for him to pursue is to add another animal to his herd. And another; and another. . . . But this is the conclusion reached by each and every rational herdsman sharing a commons. Therein is the tragedy. Each man is locked into a system that compels him to increase his herd without limit--in a world that is limited. Ruin is the destination toward which all men rush, each pursuing his own best interest in a society that believes in the freedom of the commons. Freedom in a commons brings ruin to all.



Finally, a selection of recent articles on the role of sanctions in cooperative behaviour.

Emotion expression in human punishment behavior
by Erte Xiao and Daniel Houser
PNAS May 17, 2005

Evolutionary theory reveals that punishment is effective in promoting cooperation and maintaining social norms. Although it is accepted that emotions are connected to punishment decisions, there remains substantial debate over why humans use costly punishment. Here we show experimentally that constraints on emotion expression can increase the use of costly punishment. We report data from ultimatum games, where a proposer offers a division of a sum of money and a responder decides whether to accept the split, or reject and leave both players with nothing. Compared with the treatment in which expressing emotions directly to proposers is prohibited, rejection of unfair offers is significantly less frequent when responders can convey their feelings to the proposer concurrently with their decisions. These data support the view that costly punishment might itself be used to express negative emotions and suggest that future studies will benefit by recognizing that human demand for emotion expression can have significant behavioral consequences in social environments, including families, courts, companies, and markets.

Altruistic punishment and the origin of cooperation
by James H. Fowler
PNAS May 10, 2005

How did human cooperation evolve? Recent evidence shows that many people are willing to engage in altruistic punishment, voluntarily paying a cost to punish noncooperators. Although this behavior helps to explain how cooperation can persist, it creates an important puzzle. If altruistic punishment provides benefits to nonpunishers and is costly to punishers, then how could it evolve? Drawing on recent insights from voluntary public goods games, I present a simple evolutionary model in which altruistic punishers can enter and will always come to dominate a population of contributors, defectors, and nonparticipants. The model suggests that the cycle of strategies in voluntary public goods games does not persist in the presence of punishment strategies. It also suggests that punishment can only enforce payoff-improving strategies, contrary to a widely cited "folk theorem" result that suggests that punishment can allow the evolution of any strategy.

Human behaviour: Egalitarian motive and altruistic punishment (reply)
by ERNST FEHR* AND SIMON GÄCHTER
Nature (06 January 2005);

Fehr and Gächter reply - Fowler et al. raise an important question. They correctly argue that the desire to reduce inequality may motivate cooperators who altruistically punish free riders in our experiments. Also, the evolutionary history of humans suggests that egalitarianism shaped many human cultures and that egalitarian motives may, therefore, be a powerful force behind the punishment of free riders. In addition, recently developed proximate theories, which formalize the notion of inequality aversion, also suggest that egalitarian desires may be important. Fowler et al. contrast their egalitarianism hypothesis with our view that negative emotions against free riders drive punishment.

Human behaviour: Don't lose your reputation
by ERNST FEHR
Nature (06 January 2005);

Collective action in large groups whose members are genetically unrelated is a distinguishing feature of the human species. Individual reputations may be a key to a satisfactory evolutionary explanation.

Getting to Know You: Reputation and Trust in a Two-Person Economic Exchange
by Brooks King-Casas, Damon Tomlin, Cedric Anen, Colin F. Camerer, Steven R. Quartz, P. Read Montague1
Science (1 April 2005)

Using a multiround version of an economic exchange (trust game), we report that reciprocity expressed by one player strongly predicts future trust expressed by their partner—a behavioral finding mirrored by neural responses in the dorsal striatum. Here, analyses within and between brains revealed two signals—one encoded by response magnitude, and the other by response timing. Response magnitude correlated with the "intention to trust" on the next play of the game, and the peak of these "intention to trust" responses shifted its time of occurrence by 14 seconds as player reputations developed. This temporal transfer resembles a similar shift of reward prediction errors common to reinforcement learning models, but in the context of a social exchange. These data extend previous model-based functional magnetic resonance imaging studies into the social domain and broaden our view of the spectrum of functions implemented by the dorsal striatum.

Brain Study Shows Why Revenge Is Sweet
by John Roach
for National Geographic News
National Geographic New (August 27, 2004)

Revenge is sweet. Many of us have felt that way, and now scientists say they know why.

A new brain-imaging study suggests we feel satisfaction when we punish others for bad behavior. In fact, anticipation of this pleasure drives us to crack the whip, according to scientists behind the new research.

The findings, reported in today's issue of the journal Science, may partly explain a behavior known as altruistic punishment: Why do we reprimand people who have abused our trust or broken other social rules, even when we get no direct practical benefits in return?

The Neural Basis of Altruistic Punishment
by Dominique J.-F. de Quervain, Urs Fischbacher, Valerie Treyer, Melanie Schellhammer, Ulrich Schnyder, Alfred Buck, Ernst Fehr
Science (27 August 2004)

Many people voluntarily incur costs to punish violations of social norms. Evolutionary models and empirical evidence indicate that such altruistic punishment has been a decisive force in the evolution of human cooperation. We used H2 15O positron emission tomography to examine the neural basis for altruistic punishment of defectors in an economic exchange. Subjects could punish defection either symbolically or effectively. Symbolic punishment did not reduce the defector's economic payoff, whereas effective punishment did reduce the payoff. We scanned the subjects' brains while they learned about the defector's abuse of trust and determined the punishment. Effective punishment, as compared with symbolic punishment, activated the dorsal striatum, which has been implicated in the processing of rewards that accrue as a result of goal-directed actions. Moreover, subjects with stronger activations in the dorsal striatum were willing to incur greater costs in order to punish. Our findings support the hypothesis that people derive satisfaction from punishing norm violations and that the activation in the dorsal striatum reflects the anticipated satisfaction from punishing defectors.

Sweet Revenge?
by Brian Knutson
Science(27 August 2004)

Revenge feels good! Most of us take satisfaction in punishing violators of social norms and may even incur costs to do so. In a Perspective, Knutson takes us on a joy ride through the brain to seek the areas involved in the exacting of revenge. Intriguingly, it is the striatum, a key subcortical brain structure involved in feeling satisfaction, that is activated in human volunteers subjected to PET imaging as they play a game designed to elicit acts of revenge (de Quervain et al.).

Microsocopic Images

at The Micropolitan Museum of microscopic art forms.


The fragile wing of a mosquito. If you smash a mosquito very carefully you can enjoy the beauty of its wings!


Bell animalcules are common in fresh water but can also be found in the sea. These colonial Ciliates live attached to a stalk. Find out more about their fresh water relatives on the smallest page on the web

The Poggendorff Illusion

Fig. 1. The Poggendorff illusion and its behavior. (A) When an obliquely oriented straight line is interrupted by a vertical occluder, the line segment on the right appears to be shifted downward with respect to the line segment on the left. (B) A similar effect occurs when the orientation of the interrupted line is reversed. In this case, the collinear extension on the right appears to be shifted upward. (C) When an oblique line is interrupted by parallel horizontal lines, the oblique line segments appear to be shifted horizontally with respect to each other. (D) The magnitude of the effect increases as the interrupted line is made more vertical. (E) The magnitude also increases as the width of the interruption increases. (F) The illusion is largely abolished when only the acute components of the stimulus are presented, but the effect is maintained when only the obtuse components are shown. (G) The illusion is diminished when the standard configuration is rotated so that the interrupted line is horizontal.


A new explanation for this illusion has just been published.

The Poggendorff illusion explained by natural scene geometry by Catherine Q. Howe, Zhiyong Yang, and Dale Purves in Proc. Natl. Acad. Sci. USA.

One of the most intriguing of the many discrepancies between perceived spatial relationships and the physical structure of visual stimuli is the Poggendorff illusion, when an obliquely oriented line that is interrupted no longer appears collinear. Although many different theories have been proposed to explain this effect, there has been no consensus about its cause. Here, we use a database of range images (i.e., images that include the distance from the image plane of every pixel in the scene) to show that the probability distribution of the possible locations of line segments across an interval in natural environments can fully account for all of the behavior of this otherwise puzzling phenomenon.

"Cosmic Gall" by John Updike

Neutrinos, they are very small.
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids down a drafty hall
Or photons through a sheet of glass.
They snub the most exquisite gas,
Ignore the most substantial wall,
Cold shoulder steel and sounding brass,
Insult the stallion in his stall,
And, scorning barriers of class,
Infiltrate you and me. Like tall
And painless guillotines they fall
Down through our heads into the grass.
At night, they enter at Nepal
And pierce the lover and his lass
From underneath the bed—you call
It wonderful; I call it crass.

From TELEPHONE POLES AND OTHER POEMS
(Knopf) © 1960, 1988 John Updike.
Originally in The New Yorker. All rights reserved.

Note: in the meantime, it seems neutrinos do actually have some mass, alas - but that was a pretty big surprise.


John Hoyer Updike

Max Ernst: a Retrospective

exhibit at the Metropolitan in New York - April 7, 2005–July 10, 2005. See the review by John Updike in the New York Review of Books



"The Robing of the Bride", 1939 130 x 96 cm., Venice


Europe after the Rain II. Oil on canvas. 54 x 146 cm. 1940-42. Wadsworth Atheneum, Hartford, CT, USA

Europe after the Rain, we are told, was begun by Ernst in a European prison camp and finished in the United States—a precarious transit, in that dire time, for a crusty canvas two feet by five." says Updike in his review.



Adolf Hitler and Josef Goebbels view the exhibition of "degenerate art", Munich 1937

Hitler was definitely not a fan, Ernst happened to be Jewish:



Max Ernst (French, born Germany, 1891–1976)
The Blessed Virgin Chastises the Infant Jesus Before Three Witnesses: A.B., P.E. and the Artist, 1926
Oil on canvas; 77 1/4 x 51 1/4 in. (196 x 130 cm)
Museum Ludwig, Köln
© 2004 Artists Rights Society (ARS), New York/ADAGP, Paris

According to Updike's review, "The original exhibition including Ernst's assaultive painting The Blessed Virgin Chastises the Infant Jesus before Three Witnesses: A.B., P.E., and the Artist (1926) was closed by church pressure because of it; at the Met, alone on a large wall and protected by glass against possible Christian vandals, it exerts a sensuous spell."