The Brightest Supernova Ever

Here’s the lead from the NASA release about an observation with the Chandra X-Ray [orbiting] Observatory of “the brightest supernova ever“:

May 7, 2007: The brightest stellar explosion ever recorded may be a long-sought new type of supernova, according to observations by NASA’s Chandra X-ray Observatory and ground-based optical telescopes. This discovery indicates that violent explosions of extremely massive stars were relatively common in the early universe, and that a similar explosion may be ready to go off in our own galaxy.

“This was a truly monstrous explosion, a hundred times more energetic than a typical supernova,” said Nathan Smith of the University of California at Berkeley, who led a team of astronomers from California and the University of Texas in Austin. “That means the star that exploded might have been as massive as a star can get, about 150 times that of our sun. We’ve never seen that before.”

Astronomers think many of the first stars in the Universe were this massive, and this new supernova may thus provide a rare glimpse of how those first generation stars died. It is unprecedented, however, to find such a massive star and witness its death. The discovery of the supernova, known as SN 2006gy, provides evidence that the death of such massive stars is fundamentally different from theoretical predictions.

The photographs accompanying the release are extraordinary, showing that the supernova was as bright as the core of its galaxy — that’s bright! It seems this one was bright enough that some light even reached the mainstream press, as in this story from the L.A. Times.

As additional background, may I point out my own posting called “A Star Explodes in Slow Motion“, which feature an informative excerpt from Galileo’s Finger: The Ten Great Ideas of Science, by Peter Atkins.

Noctilucent Clouds

For those who fear that there may be nothing left in the world to discover (hardly a chance!), consider this item from Space Weather News for April 25, 2007:

NIGHT-SHINING CLOUDS: NASA’s AIM spacecraft left Earth Wednesday on a two-year mission to study mysterious noctilucent (night-shining) clouds. Hovering at the edge of space, these clouds were first noticed in the 19th century; they are remarkable for their electric-blue color and sharp, wavy ripples. In recent years noctilucent clouds have been growing brighter and spreading. What causes them? Theories range from space dust to global warming. For the next two years, AIM will scrutinize the clouds from Earth orbit to learn what they may be telling us about our planet. Visit http://spaceweather.com for more information about the AIM mission, pictures of noctilucent clouds and observing tips.

“Official” Spring

Speaking of the Vernal Equinox, many people were — speaking of it — yesterday but occasionally with some imprecision, saying that spring “officially” arrived at about 2007 EDT. They would be better off saying “astronomically” arrived, since there’s nothing “official” about it: no international committee meets to set the time of the arrival of springtime. Instead, we have chosen to relate the change of seasons to clearly and precisely defined events related to the apparent motion of the sun, events that have been noted since antiquity.

Because of the tilt of the Earth’s axis of rotation (about 23.5°) relative to the plane of its orbit around the Sun, the zenith of the Sun (i.e., it’s largest angle above the horizon each day) changes with the seasons; it’s higher in the sky during summer and lower during winter.^* In other words, the Sun appears to move not only along a path across the sky (the “ecliptic”), but that path appears to move higher and lower as the year progresses.

Now, imagine a line from the center of the Earth to the Sun; where the line passes through the surface of the Earth is the point at which the Sun, at that moment, can be said to be directly overhead. Let’s call this line the “Sun Chord” — so far as I know it has no generally recognized name, and this name sounds harmonious.

As the days of the year pass, the apparent motion of the sun in the sky — or the intersection of the Sun Chord with the Earth’s surface — traces out a squished figure-eight (the “analemma“);^# the exact shape of the analemma depends on the location of the observer.

As the Sun executes its stately analemmic dance, there are fixed extremes to its motion. When the Sun appears at its northern-most point, the Sun Chord passes through the “Tropic of Cancer”, which is at a latitude of about 23.5°N; similarly, when the Sun appears at its Southern-most point, the Sun Chord passes through the “Tropic of Capricorn”, is at a latitude of about 23.5°S. It is not a coincidence that these latitudes have the same angles as the tilt of the Earth’s axis; it is a consequence of geometry. The Sun’s passing through these extreme points is called a “solstice”. In the northern hemisphere we often call the solstice that occurs in June the “summer solstice”, and the solstice in December the “winter solstice”.

Also during the year there are two times — very nearly 6 months apart and 3 months separated from each solstice — when the Sun Chord passes through the Earth’s equator, i.e., when the sun is directly overhead at the equator. When the Sun appears to be moving in a northerly direction this point is the “vernal equinox” (or “spring equinox”); when the Sun is moving in a southerly direction this point is the “autumnal equinox”. “Equinox”, of course, means “equal night”, a name given because the amount of daylight and nighttime are [roughly] equal everywhere on the Earth (except extremely near the poles, which are singular points in this geometrical picture).

And now to the point of this essay. Equinox and solstice times are mathematical concepts describing astronomical events. They occur at well-defined times that can be determined with as much precision as one would care to take. We can calculate to any number of decimal places the exact moment when the Sun Chord intersects the equator, making it possible to say that the vernal equinox occurred at seven minutes past eight (EDT) last evening.

Now, whether spring “officially” started then is another matter entirely, a matter of convention and history, but not a geometric necessity.

[After I'd started writing this piece, Isaac sent me a link to an essay on the vernal equinox in the New York Times by Natalie Angier, "The Tilted Earth at Its ‘Equal Night of Spring’ ", which adds some cultural considerations to the topic. The illustration is kind of cute, too, although it does suggest something more along the lines of a "martini equinox".]
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^*This statement is true in both northern and southern hemispheres, but the seasons are reversed, which should become clear with a moment’s reflection.

^#Yes, this is true at the equator as well: the apparent motion of the sun describes an analemma. It is a common misconception that the sun at the equator is always overhead; what is true is that day and night at the equator are always equal, but there is apparent motion of the sun by about 23.5^° to both sides of vertical.

APS Openness

Today in Bob Park’s What’s New (9 March 2007 edition) was this tidbit:

OPENNESS: THE MARCH MEETING OF THE AMERICAN PHYSICAL SOCIETY.

The commitment of physicists to the principle of openness was tested this very morning in Denver at the APS March meeting, as it has been every year for 108 years. Roy Masters, author of “God Science and Free Energy from Gravity,” was to deliver “Electricity from Gravity” at 9:36 a.m. Anyone can deliver a paper at the March Meeting. What if Masters actually succeeded in using up our gravity to keep the lights on? Not to worry.

I think all physics graduate students, sometime during their years’ long hazing, have noticed this phenomenon. It’s always good for a few giggles. But what Park says is true: any member of the APS may submit an abstract and deliver a 10-minute paper at general meetings of the society. Especially in the days when programs of abstracts were printed and distributed on paper, it was common for a few abstracts to appear for which no speaker materialized at the appointed time.

In my day there was someone who submitted an abstract at every opportunity, but who never appeared at the meetings; I don’t remember his name or where he was from. In those days one had a piece of paper on which a rectangle was inscribed; one’s abstract would be photographically reproduced and everything that was to be printed must appear withing the bounds. Said person always included a photograph of some geological feature, around which he typed his abstract, and then he filled the remaining bits of space with arrows to bits of the photo and handwritten notes. In the physics world I suppose it’s what passes for conceptual art.

Similarly, for years while I was in graduate school, there was every month, without fail, a small advertisement in the back of Physics Today from a person whose name now escapes me, who was searching for his “gamma-gamma correlations”. None of us knew what “gamma-gamma correlations” were — mostly because there is no such thing — but the advertiser never gave up hope.

Then, when I was nearing the end of graduate school, the advertisements disappeared. We were all a bit bereft at the loss of this institution. Then, after a couple of months another advertisement appeared in which the previous advertiser now promised to sell, for a small fee, something like all the secrets of the universe based on his theory about “gamma-gamma correlations”, or something like that. He had apparently found them and we could all rest again, knowing that the integrity of fringe science was safe again.

The “Woodstock of Physics”

There has been lots of talk, relatively speaking, this week about a now-famous event that took place at the annual meeting of the American Physical Society 20 years ago. The first piece that I saw was in the New York Times (Kenneth Chang, “Physicists Remember When Superconductors Were Hot“, 6 March 2007 — his piece is fine, but I think I’ll scream if anyone mentions mag-lev trains again in the same breath as superconductors, or anything else for that matter) about what quickly became known as “The Woodstock of Physics”, if you can imagine.

Today it’s the lead story in my e-mail’s “Physics News Update” (9 March 2007 edition), by Phil Schewe and Ben Stein of AIP (the American Institute of Physics is an umbrella organization that encompasses the American Physical Society, and publishes Physical Review and Physics Today, among others).

So this is the story that got everyone all excited twenty years ago. I wasn’t at that meeting — I usually attended a smaller local meeting the next month where most of my low-temperature colleagues congregated by tradition — but I certainly remember the buzz it created in the hallways near my lab. This is probably the event I will recall when people start talking again, as they seem to every generation or so, about how physics is pretty much played out and all important discoveries have already been made.

It was rather more excitement than you might expect to see among a group of typically staid physicists. By the way, this gives you a chance to see the differences between a news story written for the public, and one written with an audience of physicists in mind.

“THE WOODSTOCK OF PHYSICS,” the famous session at the March 1987 meeting of the American Physical Society, earned its nickname because of the rock-concert fervor inspired by the convergence of dozens of reports all bearing on copper-oxide superconductors. The 20th anniversary of this singular event was celebrated this week at the APS meeting in Denver.

Why such an uproar over the electrical properties of an unlikely ceramic material? Because prior to 1987 the highest temperature at which superconductivity had been observed was around 23 K [i.e., "Kelvins", centigrade sized degrees where 0 K is "absolute zero"]. And suddenly a whole new set of compounds–not metallic alloys but crystals whose structure put them within a class of minerals known as perovskites–with superconducting transition temperatures above 35 K and eventually 100 K generated an explosion of interest among physicists. Because of the technological benefits possibly provided by high-temperature superconductivity (HTSC)—things like bulk power storage and magnetically levitated trains—the public was intrigued too.

This week’s commemoration of the Woodstock moment (the months of feverish work leading up to the 1987 meeting) provided an excellent history lesson on how adventurous science is conducted. Georg Bednorz (IBM-Zurich), who with Alex Mueller made the initial HTSC discovery, recounted a story of frustration and exhilaration, including working for years without seeing clear evidence for superconductivity; having to use borrowed equipment after hours; overcoming skepticism from IBM colleagues and others who greatly doubted that the cuprates could support supercurrents, much less at unprecedented temperatures; and finally arriving at the definitive result–superconductivity at 35 K in a La-Ba-Cu-O compound. In October 1986 Bednorz and Mueller prepared a journal article confirming their initial finding in the form of observing the telltale expulsion of magnetism (the Meissner effect) from the material during the transition to superconductivity. Submitting this paper, however, required the approval of the IBM physics department chairman, Heinrich Rohrer who, that very week, had been declared a co-winner of the Nobel prize for his invention of the scanning tunneling microscope (STM). Afraid that he would not be able to obtain the preoccupied Rohrer’s attention, Bednorz obtained the needed signature by thrusting the approval form at Rohrer as if he (Bednorz) desired only a celebratory autograph. A scant year later Bednorz and Mueller pocketed their own Nobel Prize.

The IBM finding was soon seconded by work in Japan and at the University of Houston, where Paul Chu, testing a YBaCuO compound, was the first to push superconductivity above the temperature of liquid nitrogen, 77 K. Very quickly a gold rush began, with dozens of condensed matter labs around the world dropping what they were doing in order to irradiate, heat, chill, squeeze, and magnetize the new material. They tweaked the ingredients list, hoping to devise a sample that superconducted at still higher temperatures or with a greater capacity for carrying currents. At this week’s APS meeting Chu said that he and his colleagues went for months on three hours’ sleep per night. Several other speakers at the 2007 session spoke of the excitement of those few months in 1987 when-according to such researchers as Marvin Cohen (UC Berkeley) and Douglas Scalapino (UC Santa Barbara)-the achievement of room-temperature superconductivity did not seem inconceivable.

The Woodstock event, featuring 50 speakers delivering their fresh results at a very crowded room at the New York Hilton Hotel until 3:15 am, was a culmination. In following years, HTSC progress continued on a number of fronts, but expectations gradually became more pragmatic. Paul Chu’s YBaCuO compound, under high-pressure conditions, still holds the transition
temperature record at 164 K. Making lab samples had been easy compared to making usable power-bearing wires in long spools, partly because of the brittle nature of the ceramic compounds and partly because of the tendency for potentially superconductivity-quenching magnetic vortices to form in the material. Paul Grant, in 1987 a scientist at IBM-Almaden, pointed out that HTSC applications have largely not materialized. No companies are making a profit from selling HTSC products. Operating under the principle of “You get what you need,” Grant said, superconducting devices operating at liquid-nitrogen temperatures weren’t better enough so as to displace devices operating at liquid-helium temperatures.

Nevertheless, the mood of the 2007 session (Woodstock20) was upbeat. Bednorz said the 1986/87 work showed that a huge leap forward could still take place in a mature research field whose origins dated back some 70 years. Bednorz felt that another wave of innovation could occur. Paul Chu ventured to predict that within ten years, HTSC products would have an impact in the power industry. Paul Grant referred to the study of superconductivity as the “cosmology of condensed matter physics,” meaning that even after decades of scrutiny there was still much more to learn about these materials in which quantum effects, manifested over macroscopic distances, conspire to make electrical resistance vanish, a phenomenon which at some basic level might also be related to the behavior of protons inside an atomic nucleus and the cores of distant neutron stars.

(Photographs and an original summary press release from the 1987 meeting is available at our Physics News Graphics website, www.aip.org/png)

Ball’s Critical Mass

A week or two ago I finally finished reading Philip Ball’s Critical Mass : How One Thing Leads to Another. New York : Farrar, Straus and Giroux, 2004. (My book note about it, with different quotations, is here.)

I’ve become quite a fan now of Philip Ball’s writing; previously I was wowed by Bright Earth, and The Ingredients. Happily for me, there are still some of his books that I haven’t read.

This one struck me very personally in a couple of ways. Loosely speaking, it’s about modern attempts to apply modern concepts in condensed-matter physics (encompassing thermodynamics, statistical physics, fluid dynamics, critical phenomena, chaos theory and others) to social systems and the collective behavior of humans. Once upon a time I did experimental research in condensed-matter physics, including several of the disciplines he talks about. Today, with Ars Hermeneutica, I’m quite interested in what I call “appropriate quantification”, or how to apply statistical models to collective human behavior. Thus, there is a lot of resonance here. When I think about how irritating this book could have been had it been written by a less-accomplished science writer, it makes me admire Ball’s talents that much more.

These are some excerpts that I marked to keep here in my common-place book.

To kick things off, here’s an excerpt he quotes from C.P. Snow’s famous book The Two Cultures, about the divide (real or imagined) between the sciences and the humanities. This is all Snow:

A good many times I have been present at gatherings of people who, by the standards of the traditional culture, are thought highly educated and who have with considerable gusto been expressing their incredulity at the illiteracy of scientists. Once or twice I have been provoked and have asked the company how many of them could describe the Second Law of Thermodynamics. The response was cold: it was also negative. Yet I was asking something which is about the scientific equivalent of: Have you read a work of Shakespeare’s. [p.38 of Critical Mass]

Ball began his discussion by looking at the earliest attempt to make a science of social interaction, Hobbe’s Leviathan. Later on, he wrote about how earlier ideas propagated into today’s economic thinking.

The social contract proposed by Hobbes might sound like a forerunner of those advocated by John Locke (1623–1704) and Jean-Jacques Rousseau (1712–1778), but it is instead the reverse. To Locke and Rousseau, the power conferred upon the head of state comes with an obligation to serve the interests of the populace; for Hobbes, the common people are contracted to serve their ruler. For Hobbes, the principal fear was of anarchy; for Locke it was the abuse of power, which is why he saw the need for safeguards to avoid absolutism.

But although apparently a proponent of autocracy, Hobbes also provides arguments that can be used to support both bourgeois capitalism and liberalism. Although he expressed an aversion to the way the mercantile society bred men whose “only glory [is] to grow excessively rich by the wisdom of buying and selling,” which they do “by making poor people sell their labour to them at their own prices,” he saw bourgeois culture as largely inevitable, and sought a system that would accommodate its selfish tendencies without conflict. To this end he left it to the market to assign the value of everything, people included: “The value of all things contracted for, is measured by the Appetite of the Contractors: and therefore the just value, is that which they be contracted to give.” This fee-market philosophy found voice in Adam smith’s Wealth of Nations in the following century. Those in Britain and the United States (and indeed elsewhere) who lived through the 1980s will recognize it as an attitude that did not wane with the Age of Enlightenment. [p. 29]

After we’d spent quite a bit of time using scientific models to understand some of the complexity of the market and larger economic systems, suddenly traditional economic theories seems hopelessly naive and more the product of wishful thinking than critical thinking.

So deeply entrenched is the free-market philosophy in American economic theory today (I am talking here about the pundits who exert a real influence–the TV analysts, the Wall Street Journal op-ed columnists, the think-tankists, and all too often the White House advisors–but not the academic economists) that the supporters of this creed are hoping even to ride out the catastrophic stock market collapse that is proceeding at full throttle at the time of writing. They place the blame on a few corrupt CEOs, on government policies, on fickle small investors, on labor unions, on left-wing critics who spread doubt and negative thinking–anywhere but on the market itself. If only all these people would behaved, say the free-marketeers, stocks would keep rising forever. [pp. 224--225]

Later, he moved on to using ideas from critical phenomena to look at systems that can apparently change their states spontaneously and suddenly. The key concept here is that of thermodynamic fluctuations.

One experimental peculiarity that the theory [a late 19th century by physicist van der Waals) did embrace was the extraordinary sensitivity of the critical point. A system near its critical state becomes extremely responsive to disturbances. If you squeeze a substance, it shrinks in volume. The resistance it offers to the is compression is a measure of its so-called compressibility A rubber ball is more compressible than a steel, ball, and a gas is typically much more compressible than a liquid--one can squeeze it more easily. At the critical point of a liquid and gas, the fluid becomes absurdly compressible--in fact, more or less infinitely so. In principle, the gentlest squeeze is sufficient to collapse a critical fluid into invisibility. This sounds absurd, and experimentally one can never observe such extreme behavior, because maintaining a substance exactly at its critical point is too difficult--the critical state is too unstable. but one can see the compressibility start to increase very rapidly as the critical point is approached. [p. 228]

A correction: the fluctuations are unstable only below the critical temperature; above, they are stable and can grow very large if one can contrive to get the fluid close enough to the critical point and keep it there. I once was able to do that. It was such fluctuations that we were studying with our Zeno space-shuttle experiment in the early 90s. We were able to keep a very small fluid sample stably poised some 3-millionths of a Kelvin (i.e., a centigrade degree) above its critical temperature to study the density fluctuations. The compressibility was so high that we had to do this in earth orbit (so called “micro-gravity”) so that gravity itself would not move the fluid away from the critical point.

Still later the topic was networks and how they organize their connections and related topics, including a discussion of the Kevin Bacon degrees-of-separation game. Can all actors be connected to Kevin Bacon in just 6 or fewer steps? Is this deeply significant? Not really.

And what of the must burning issue: Is Kevin Bacon really the center of the movie universe? To answer this, one must calculate the average Bacon Number for the entire network and see how it compares with the equivalent measures for the other actors: the Elvis Number, the Bogart Number, the Brando Number, and so on. If Kevin Bacon really is the most important linchpin in the network, all other actors will, on average, be closer to him than to anyone else.

It turns out that not only is Kevin Bacon not the most important hub of the network, he is not even in the top one thousand (the list of course changes daily as new films are made). Currently up at the top is Rod Steiger (the average Steiger Number is 2.652), followed by Christopher Lee, Dennis Hopper, Donald Pleasence, and Donald Sutherland (who appeared in the movie version of Six Degrees of Separation). Marlon Brando is number 202, Frank Sinatra number 443. By the time we get to Kevin Bacon’s level., the differences in the average Actor Number that separate successive actors in the list are tiny, about 0.0001.

So why was Kevin Bacon picked for this game? The answer contains the entire essence of a small world: in such a network, everyone appears to be at the center. Some are more “central” than others–but not by very much. Even relatively minor actors like Eddie Albert have a comparable network status to major stars. (Donald Pleasence was a fine actor but hardly a superstar.) [pp. 369--370]

Finally, a little quotation from Pericles [quoted on p. 425]:

Even if only a few of us are capable of devising a policy or putting it into practice, all of us are capable of judging it.

Mandelbrot’s Vegetable Stand

I can’t say I expected to see fractals mentioned in an article about cauliflower — or a casual mention of “the Mandelbrot theory” by a cauliflower farmer — but I wasn’t terribly surprised either. I’ve seen these Romanesco cauliflowers and they are visually astonishing, regardless of whether one is a “Caltech guy” or not. I’m not convinced that our author has a deep understanding of fractals, but she manages to capture the spirit and not do much violence to the idea of self-similarity (at all length scales), so Mrs. Scattergood gets the gold star in science communication for today.

But the Romanesco cauliflower is an heirloom and isn’t to be confused with green cauliflower, or broccoflower, which is a cross between a broccoli and a cauliflower. Romanesco is astonishing in appearance, as much for its composition as for its color. Lime-green in hue, a head (or curd) of Romanesco is a near-perfect example of naturally occurring fractal: a fragmented geometric shape composed of smaller parts that are copies of the whole. The cauliflower resembles an M.C. Escher print more than something you’d find naturally occurring in your vegetable garden.

“The guys at Caltech come down and study them,” says Alex Weiser of Weiser Family Farms, in whose farmers market stands you’ll find all three varieties of cauliflower. “Something about the Mandelbrot theory.” But you don’t need a degree in mathematics to cook them. Whether they’re fully grown or beautiful babies, Weiser prefers his cauliflower roasted, with just a little sea salt and olive oil splashed on before they’re put in a hot oven.

[Amy Scattergood, "A Brilliant Comeback", Los Angeles Times via Baltimore Sun, undated, read on 19 January 2006.]

Earth from Saturn

This is a most unusual, beautiful, and evocative photograph — and it is an actual photographic image, albeit a composite. The photographer was the Cassini-Huygens spacecraft. On this occasion Saturn interposed itself between the Sun and the spacecraft, thus creating this beautifully backlit composition. Although it is hard to make out in this small version, the dot in the upper-left quadrant of the lower image, indicated by the text, is the Earth, seen through Saturn’s rings.

This version of what is sure to become a famous image came to my attention through NASA’s Earth Observatory website. Visit the original page (“A View of Earth from Saturn“) for larger versions of the image, and lots of information about the image and the Cassini-Huygens mission.

Here is a short excerpt from that page:

This beautiful image of Saturn and its rings looks more like an artist’s creation than a real image, but in fact, the image is a composite (layered image) made from 165 images taken by the wide-angle camera on the Cassini spacecraft over nearly three hours on September 15, 2006. Scientists created the color in the image by digitally compositing ultraviolet, infrared, and clear-filter images and then adjusting the final image to resemble natural color. (A clear filter is one that allows in all the wavelengths of light the sensor is capable of detecting.) The bottom image is a closeup view of the upper left quadrant of the rings, through which Earth is visible in the far, far distance.

A Natural Selection

This week’s beard is worn by none other than Charles Darwin (12 February 1809 – 19 April 1882), the infamous, the reviled, the namesake of the dreaded Darwinism, author of On the Origin of Species by Means of Natural Selection.

Quite without my really meaning for it to happen, the past month or more has been my Darwin month: I’ve been reading books with Darwin and Darwinism (or, perhaps more precisely, “post-synthesis neo-Darwinism”) as their themes, and it’s been a rewarding period of Darwinian immersion. The books in question are The Blind Watchmaker, by Richard Dawkins, Darwin’s Dangerous Idea, by Daniel Dennett, and “The Reluctant Mr. Darwin”, by David Quammen. The Dawkins is the only one I’ve finished so far — the others are in progress. Sometime after they’re all finished I expect I’ll write some Book Notes about them.

The Dawkins and the Dennett book both have very similar goals, namely, to elucidate the central idea of Darwinism^* at some length to reduce the mystery, misunderstanding, and hostility that it engenders. They both do a good job in markedly different voices: Dawkins is a high-energy, exuberant acolyte, Dennett a more deliberate and philosophical adherent. Quammen’s book, it seems, intends to be an intellectual biography of how Darwin came to his theory about evolution and what happened when he finally arrived there; I’m still near the beginning but it promises to be a good trip.

In his introduction, Quammen touches on those famous polls by Gallup and the Pew Research Center that keeps finding that some 45% of the American people believe that “God created human beings pretty much in their present form at one time within the last 10,000 years or so”; only 13% agreed that humans have developed from other life forms without any intervention from God! He writes:

Maybe the polls are invalid. Maybe the numbers would be much different in England or Sweden or India. Maybe the same distinctly American mixture of skepticism and evangelicalism that led to the Scopes trial, in 1925, continues to animate many citizens who would simply rather take their biology from scripture than from science. Maybe the question of human evolution is misleading and inordinately touchy; maybe Gallup and Pew should be asking whether God created, let’s say, tree kangaroos in their present form. Or maybe … who knows? I don’t claim to have any definitive explanation for such an extreme level of skepticism and willful antipathy toward such a well-established scientific discovery. Frankly, it mystifies me. But certainly those Gallup results–combined with the continuing political offensive against teaching evolutionary biology in public schools–testify that Charles Darwin isn’t just perennially significant. He’s also urgently relevant to education and governance.

I have agree with Quammen when he says “Frankly, it mystifies me.” Although I didn’t do it because of Darwinism as such, or to fight specifically against creationist incursions, this mystification is certainly part of the reason I founded Ars Hermeneutica, Limited. Now, whether we’ll be able to understand or do anything about the problem is an entirely different animal, but we intend to try.
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^*That species are not persistent and unchanging, but that species evolve from other species through the agency of natural selection.

Welcome the Sun!

This is the day of the year, 7 December, when I celebrate my own festival of light to welcome the return of the sun.

No, it is not the shortest day of the year, the day with the least amount of sunlight where I am (about 39 degrees north, 76 degrees, 46 minutes west — but the effect only depends on latitude), because it is not the Winter Solstice, which occurs about 21 December.

It is, however, the earliest sunset of the year, a more interesting inflection point. Since I rarely experience sunrise, at least by choice, this is psychologically much more important. Beyond today, the day will appear to me ever so slowly to be getting longer again because after today the sun will start going down later in the evening.

The effect is hardly noticeable at first,^* but by the time we get to the Solstice the day-to-day change in sun-setting time will be noticeably larger. I was happy when I learned about this, the pre-Solstice early-sun-setting day, because it explained for me the feeling I’d always had that once we got past the Solstice it seemed as though the days started getting longer very quickly.^#

The reason for the phenomenon is tougher to explain than to comprehend; I looked at three different versions (one, two, and three), none of which struck me as entirely satisfactory, but feel free to have a go. To make a long story short, I can point out that if the earth weren’t tilted then this curious misalignment of times wouldn’t happen. But then, neither would the seasons, and neither would the apparent position of the sun’s zenith in the sky^** change from day to day.^##

Regardless of all that, I’m always happy to see the sun starting to linger longer at the end of each day.
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^*For those with a calculus vocabulary, the curve of earliest sunset times as a function of date has just passed an extremum and the derivative is still very near zero.

^#Finally, this gives you something to do with those previously useless reports in the newspaper or in the nightly weather forecast that give you sunset and sunrise time: plot the curves for yourself and see when the minima and maxima in sunset and sunrise occur at your latitude.

^**Known as the “analemma”, the figure-8 shape found on precision sun-dials and on globes of the Earth.

^##How much it changes day-to-day depends on one’s latitude and is described by the grandly named “Equation of Time”.