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Sunday, July 31, 2005

Solar System Live: Kuiper Belt Objects Update

With all the recent news about the discovery of a Kuiper Belt Object larger than Pluto (here's an update from Sky & Telescope), I've modified Solar System Live so as not to truncate the orbits of these remote objects at what used to be called the edge of the Solar System; the Orrery display is now automatically rescaled (up to a limit of 150 astronomical units) to fit the orbit of the object being tracked.

Here is the orbit of 2003 UB313, which has been getting all the press. I've chosen the heliocentric viewpoint to show how inclined the orbit is with respect to the plane of the ecliptic, as well as its eccentricity. (It's a curious coincidence [and nothing more] that the inclination and eccentricity are both about 44.2°.)

A few days earlier, the discovery of another big Kuiper Belt Object, 2003 EL61, was announced. Despite early reports, this one is smaller than Pluto. It has a tiny satellite, which permits its mass to be determined, which is about a quarter of Pluto's.

Now that people know to look for objects way out of the ecliptic as far out as 100 AU, I'll bet these are just the first of a bunch to be found in the coming years.

Posted at 16:31 Permalink

Friday, July 29, 2005

Reading List: Reminiscences of a Stock Operator

Lefevre, Edwin. Reminiscences of a Stock Operator. New York: John Wiley & Sons, [1923] 1994. ISBN 0-471-05970-6.
This stock market classic is a thinly fictionalised biography of the exploits of the legendary speculator Jesse Livermore, written in the form of an autobiography of "Larry Livingston". (In 1940, shortly before his death, Livermore claimed that he had actually written the book himself, with writer Edwin Lefevre acting as editor and front-man; I know of no independent confirmation of this claim.) In any case, there are few books you can read which contain so much market wisdom packed into 300 pages of entertaining narrative. The book was published in 1923, and covers Livermore/Livingston's career from his start in the bucket shops of Boston to a millionaire market mover as the great 1920s bull market was just beginning to take off.

Trading was Livermore's life; he ended up making and losing four multi-million dollar fortunes, and was blamed for every major market crash from 1917 through the year of his death, 1940. Here is a picture of the original wild and woolly Wall Street--before the SEC, Glass-Steagall, restrictions on insider trading, and all the other party-pooping innovations of later years. Prior to 1913, there were not even any taxes on stock market profits. Market manipulation was considered (chapter 19) "no more than common merchandising processes", and if the public gets fleeced, well, that's what they're there for! If you think today's financial futures, options, derivatives, and hedge funds are speculative, check out the description of late 19th century "bucket shops": off-track betting parlours for stocks, which actually made no transactions in the market at all. Some things never change, however, and anybody who read chapter 23 about media hyping of stocks in the early decades of the last century would have been well cautioned against the "perma-bull" babblers who sucked the public into the dot-com bubble near the top.

Posted at 22:01 Permalink

Thursday, July 28, 2005

Privacy: Murderer Ratted Out by Customer Fidelity Card

According to an article in the July 28, 2005 issue of L'Hebdo, on October 29, 2003 an immigrant from Kosovo living in Winterthur, Switzerland murdered his wife with 20 blows by a hammer. At trial, he claimed that the murder was a crime of passion, and that he seized the hammer, which happened to be at hand, in a fit of anger.

Unfortunately for the defendant, when he bought the hammer immediately before returning home to commit the crime, he handed over his customer fidelity card, not wanting to forego the rebate points due for the purchase of the CHF 21 murder weapon. The store in question not only records the identity of the card-holder and the amount of the purchase, but a detailed list of each item bought. This database entry, introduced at the trial, sufficed to prove premeditated murder, for which the perpetrator was sentenced to 13 years in prison. (Yes, that seems a tad light for killing your wife with a hammer, but that's how murder sentences in Switzerland tend to run; come for the scenery, stay for the murder. Note, however, that the convicted was 73 years old and won't be getting out until he's 86.)

Both of the two largest Swiss retailers report they've issued about 2.1 million customer fidelity cards, which is a pretty remarkable market penetration when you consider that there are a total of 3.2 million households in the country. Most people don't care if the store keeps track of how much milk, bread, and cheese they buy, but when purchasing murder weapons, it's best not to let them swipe your card.

Posted at 21:09 Permalink

Reading List: Persistence, Macros, XHTML, and Tools Download

I have just completed an overhaul of the tools used to produce the reading list document. Previously, while direct links to books were persistent ("permalinks" which did not change when books were added to the list), links to lists of books by author or topic were ephemeral--most of them changed every time a new author or topic was added. The new version creates the names for author and topic index files by transforming the actual author or topic name into a unique form suitable for use as a file name, which guarantees that links to the HTML index files won't break. For example, is is now possible to link directly to books by E. E. "Doc" Smith, or books on economics.

In addition, the text files from which the reading list Web tree is built now may contain macros which are expanded into frequently-used HTML links. A complete link to a book on Amazon.com, including associate program information and target window, may be written as just "<Amazon ISBN>", where ISBN is the book's International Standard Book Number. (Did you know, by the way, that the process of transitioning ISBNs from the current 10-digit standard to 13-digit ISBNs is now afoot, with January 1, 2007 set as the date when the publishing industry is supposed to use 13-digit ISBN-13 numbers exclusively? . . .always scribble, scribble, scribble.)

The HTML files generated for the reading list are now XHTML 1.0 compliant, and a validator button has been added to the navigation panel which validates whatever document is shown in the main document frame. Since the comments for a book may contain arbitrary HTML markup, care must be taken not to use something which violates the XHTML 1.0 standard. The entire book list may be validated by displaying "All Books" and then clicking the validate button. (This is a big file, takes a while to transfer, and may time out; if it does, the individual year documents can be validated successively.)

Finally, the tools used to build the reading list are now available for downloading, as a GZIP compressed TAR archive containing the Perl program which generates the HTML tree and all the support files (style sheets, static HTML documents, images, etc.) it references. Little or no effort has been expended to make these tools and documents portable--while they'll probably work on any system with a recent version of Perl, you'll have to make lots of little changes to customise the results for your own site. This will involve digging into the code, which is utterly undocumented and completely unsupported--you are entirely on your own.

Posted at 16:28 Permalink

Monday, July 25, 2005

Linux: Fedora Core 3 Kernel 2.6.12-1.1372_FC3smp Doesn't Boot

After 8 days running the single-processor 2.6.12-1.1372_FC3 kernel on the server farm management machine (a re-purposed Dell Inspiron laptop configured, from a software standpoint, identically to the dual processor hyper-threaded server machines), I installed the multi-processor version of this kernel, 2.6.12-1.1372_FC3smp on the "pathfinder" server. When I attempted to reboot it to install this kernel, the reboot crashed with a kernel panic early in the reboot process (well before any damage was done to file systems). I power cycled the machine, reverted to the earlier 2.6.11-1.35_FC3smp kernel, and all was well.

This appears to be a known problem. This bug report describes precisely the symptoms I encountered. I haven't tried booting the single processor kernel on the pathfinder server since production servers need to be able to use all processors to handle the load.

Posted at 00:18 Permalink

Sunday, July 24, 2005

Your Sky: Asteroid and Hyperbolix

No, not them! I've integrated the Landgraf/Stumpff algorithm for determination of the position of bodies on parabolic and hyperbolic orbits into Your Sky, which permits computation of the position of all catalogued objects on hyperbolic heliocentric orbits. (Such bodies are rare--all are comets whose orbits have been perturbed by planets during their most recent passage through the solar system to put them on an escape trajectory.) The algorithm handles eccentricities as great as 1.1, which more than suffices since no object in the JPL catalogue of comets with well-known orbital elements has an eccentricity as high as 1.06.

To demonstrate, you can plot the current position of Comet Bowell (C/1980 E1) which, with an eccentricity of 1.056, has the most hyperbolic orbit of any catalogued comet. Earlier versions of Your Sky would have abandoned the calculation of the position of this comet upon discovering it was on an escape trajectory, while the new release correctly plots it receding into the void more than one and half times the distance of Pluto from the Sun.

Posted at 23:09 Permalink

Reading List: Aagaard's Africa

Aagaard, Finn. Aagaard's Africa. Washington: National Rifle Association, 1991. ISBN 0-935998-62-4.
The author was born in Kenya in 1932 and lived there until 1977 when, after Kenya's ban on game hunting destroyed his livelihood as a safari guide, he emigrated to the United States, where he died in April 2000. This book recounts his life in Kenya, from boyhood through his career as a professional hunter and guide. If you find the thought of hunting African wildlife repellent, this is not the book for you. It does provide a fine look at Africa and its animals by a man who clearly cherished the land and the beasts which roam it, and viewed the responsible hunter as an integral part of a sustainable environment. A little forensic astronomy allows us to determine the day on which the kudu hunt described on page 124 took place. Aagaard writes, "There was a total eclipse of the sun that afternoon, but it seemed a minor event to us. Laird and I will always remember that day as 'The Day We Shot The Kudu'." Checking the canon of 20th century solar eclipses shows that the only total solar eclipse crossing Kenya during the years when Aagaard was hunting there was on June 30th, 1973, a seven minute totality once in a lifetime spectacle. So, the kudu hunt had to be that morning. To this amateur astronomer, no total solar eclipse is a minor event, and the one I saw in Africa will forever remain a major event in my life. A solar eclipse with seven minutes of totality is something I shall never live to see (the next occurring on June 25th, 2150), so I would have loved to have seen the last and would never have deemed it a "minor event", but then I've never shot a kudu the morning of an eclipse!

This book is out of print and used copies, at this writing, are offered at outrageous prices. I bought this book directly from the NRA more than a decade ago--books sometimes sit on my shelf a long time before I read them. I wouldn't pay more than about USD 25 for a used copy.

Posted at 01:05 Permalink

Saturday, July 23, 2005

Solar System Live: Orbital Elements Upgrade

Building on the recent upgrade to Your Sky, Solar System Live now also supports orbital elements in the formats used by the IAU Minor Planet Center's Ephemeris Service and the DASTCOM Small-Body Orbital Elements database from the Solar System Dynamics group at JPL. This means you can plot the orbits of asteroids and comets by copying and pasting orbital elements in either of these formats into the Solar System Live request form. All orbital element formats previously supported by Solar System Live continue to work as well.

Support of JPL orbital elements means you can now look up periodic comets, asteroids by name, and asteroids by number in the Your Sky object catalogues, updated daily from the master JPL database, then cut and paste the orbital elements into Solar System Live for an Orrery view of the object's orbit. Eventually I'll add an "Orrery View" button to the Your Sky virtual telescope to automate this process.

This version of Solar System Live incorporates the Landgraf/Stumpff algorithm for near-parabolic motion from chapter 35 of Jean Meeus's Astronomical Algorithms, which permits computation of the position of comets on hyperbolic orbits with eccentricities as high as 1.1. Since no comet catalogued in the JPL database has an eccentricity higher than 1.06, this handles all bodies with well known orbits.

To demonstrate the new orbital element formats, the following links will display the orbit of the recently-clobbered comet Comet 9P/Tempel 1 with orbital elements in:

Both of these links will show the current position of the comet at the time they are clicked.

Posted at 21:01 Permalink

Thursday, July 21, 2005

Reading List: Secrets of the Kingdom

Posner, Gerald L. Secrets of the Kingdom. New York: Random House, 2005. ISBN 1-4000-6291-8.
Most of this short book (196 pages of main text) is a straightforward recounting of the history of Saudi Arabia from its founding as a unified kingdom in 1932 under Ibn Saud, and of the petroleum-dominated relationship between the United States and the kingdom up to the present, based almost entirely upon secondary sources. Chapter 10, buried amidst the narrative and barely connected to the rest, and based on the author's conversations with an unnamed Mossad (Israeli intelligence) officer and an unidentified person claiming to be an eyewitness, describes a secret scheme called "Petroleum Scorched Earth" ("Petro SE") which, it is claimed, was discovered by NSA intercepts of Saudi communications which were shared with the Mossad and then leaked to the author.

The claim is that the Saudis have rigged all of their petroleum infrastructure so that it can be destroyed from a central point should an invader be about to seize it, or the House of Saud fall due to an internal revolution. Oil and gas production facilities tend to be spread out over large areas and have been proven quite resilient--the damage done to Kuwait's infrastructure during the first Gulf War was extensive, yet reparable in a relatively short time, and the actual petroleum reserves are buried deep in the Earth and are essentially indestructible--if a well is destroyed, you simply sink another well; it costs money, but you make it back as soon as the oil starts flowing again. Refineries and storage facilities are more easily destroyed, but the real long-term wealth (and what an invader or revolutionary movement would covet most) lies deep in the ground. Besides, most of Saudi Arabia's export income comes from unrefined products (in the first ten months of 2004, 96% of Saudi Arabia's oil exports to the U.S. were crude), so even if all the refineries were destroyed (which is difficult--refineries are big and spread out over a large area) and took a long time to rebuild, the core of the export economy would be up and running as soon as the wells were pumping and pipelines and oil terminals were repaired.

So, it is claimed, the Saudis have mined their key facilities with radiation dispersal devices (RDDs), "dirty bombs" composed of Semtex plastic explosive mixed with radioactive isotopes of cesium, rubidium (huh?), and/or strontium which, when exploded, will disperse the radioactive material over a broad area, which (p. 127) "could render large swaths of their own country uninhabitable for years". What's that? Do I hear some giggling from the back of the room from you guys with the nuclear bomb effects computers? Well, gosh, where shall we begin?

Let us commence by plinking an easy target, the rubidium. Metallic rubidium burns quite nicely in air, which makes it easy to disperse, but radioactively it's a dud. Natural rubidium contains about 28% of the radioactive isotope rubidium-87, but with a half-life of about 50 billion years, it's only slightly more radioactive than dirt when dispersed over any substantial area. The longest-lived artificially created isotope is rubidium-83 with a half-life of only 86 days, which means that once dispersed, you'd only have to wait a few months for it to decay away. In any case, something which decays so quickly is useless for mining facilities, since you'd need to constantly produce fresh batches of the isotope (in an IAEA inspected reactor?) and install it in the bombs. So, at least the rubidium part of this story is nonsense; how about the rest?

Cesium-137 and strontium-90 both have half-lives of about 30 years and are readily taken up and stored in the human body, so they are suitable candidates for a dirty bomb. But while a dirty bomb is a credible threat for contaminating high-value, densely populated city centres in countries whose populations are wusses about radiation, a sprawling oil field or petrochemical complex is another thing entirely. The Federation of American Scientists report, "Dirty Bombs: Response to a Threat", estimates that in the case of a cobalt-salted dirty bomb, residents who lived continuously in the contaminated area for forty years after the detonation would have a one in ten chance of death from cancer induced by the radiation. With the model cesium bomb, five city blocks would be contaminated at a level which would create a one in a thousand chance of cancer for residents.

But this is nothing! To get a little perspective on this, according to the U.S. Centers for Disease Control's Leading Causes of Death Reports, people in the United States never exposed to a dirty bomb have a 22.8% probability of dying of cancer. While the one in ten chance created by the cobalt dirty bomb is a substantial increase in this existing risk, that's the risk for people who live for forty years in the contaminated area. Working in a contaminated oil field is quite different. First of all, it's a lot easier to decontaminate steel infrastructure and open desert than a city, and oil field workers can be issued protective gear to reduce their exposure to the remaining radiation. In any case, they'd only be in the contaminated area for the work day, then return to a clean area at the end of the shift. You could restrict hiring to people 45 years and older, pay a hazard premium, and limit their contract to either a time period (say two years) or based on integrated radiation dose. Since radiation-induced cancers usually take a long time to develop, older workers are likely to die of some other cause before the effects of radiation get to them. (This sounds callous, but it's been worked out in detail in studies of post nuclear war decontamination. The rules change when you're digging out of a hole.)

Next, there is this dumb-as-a-bag-of-dirt statement on p. 127:

Saudi engineers calculated that the soil particulates beneath the surface of most of their three hundred known reserves are so fine that radioactive releases there would permit the contamination to spread widely through the soil subsurface, carrying the radioactivity far under the ground and into the unpumped oil. This gave Petro SE the added benefit of ensuring that even if a new power in the Kingdom could rebuild the surface infrastructure, the oil reserves themselves might be unusable for years.
Hey, you guys in the back--enough with the belly laughs! Did any of the editors at Random House think to work out, even if you stipulated that radioactive contamination could somehow migrate from the surface down through hundreds to thousands of metres of rock (how, due to the abundant rain?), just how much radioactive contaminant you'd have to mix with the estimated two hundred and sixty billion barrels of crude oil in the Saudi reserves to render it dangerously radioactive? In any case, even if you could magically transport the radioactive material into the oil bearing strata and supernaturally mix it with the oil, it would be easy to separate during the refining process.

Finally, there's the question of why, if the Saudis have gone to all the trouble to rig their oil facilities to self-destruct, it has remained a secret waiting to be revealed in this book. From a practical standpoint, almost all of the workers in the Saudi oil fields are foreigners. Certainly some of them would be aware of such a massive effort and, upon retirement, say something about it which the news media would pick up. But even if the secret could be kept, we're faced with the same question of deterrence which arose in the conclusion of Dr. Strangelove with the Soviet doomsday machine--it's idiotic to build a doomsday machine and keep it a secret! Its only purpose is to deter a potential attack, and if attackers don't know there's a doomsday machine, they won't be deterred. Precisely the same logic applies to the putative Saudi self-destruct button.

Now none of this argumentation proves in any way that the Saudis haven't rigged their oil fields to blow up and scatter radioactive material on the debris, just that it would be a phenomenally stupid thing for them to try to do. But then, there are plenty of precedents for the Saudis doing dumb things--they have squandered the greatest fortune in the history of the human race and, while sitting on a quarter of all the world's oil, seen their per capita GDP erode to fall between that of Poland and Latvia. If, indeed, they have done something so stupid as this scorched earth scheme, let us hope they manage the succession to the throne, looming in the near future, in a far more intelligent fashion.

Posted at 23:57 Permalink

Sunday, July 17, 2005

Reading List: Rocket Boys

Hickam, Homer H., Jr. Rocket Boys. New York: Doubleday, 1998. ISBN 0-385-33321-8.
The author came of age in southern West Virginia during the dawn of the space age. Inspired by science fiction and the sight of Sputnik gliding through the patch of night sky between the mountains which surrounded his coal mining town, he and a group of close friends decided to build their own rockets. Counselled by the author's mother, "Don't blow yourself up", they managed not only to avoid that downside of rocketry (although Mom's garden fence was not so lucky), but succeeded in building and launching more than thirty rockets powered by, as they progressed, first black powder, then melted saltpetre and sugar ("rocket candy"), and finally "zincoshine", a mixture of powdered zinc and sulphur bound by 200 proof West Virginia mountain moonshine, which propelled their final rocket almost six miles into the sky. Their efforts won them the Gold and Silver award at the National Science Fair in 1960, and a ticket out of coal country for the author, who went on to a career as a NASA engineer. This is a memoir by a member of the last generation when the U.S. was still free enough for boys to be boys, and boys with dreams were encouraged to make them come true. This book will bring back fond memories for any member of that generation, and inspire envy among those who postdate that golden age.

This book served as the basis for the 1999 film October Sky, which I have not seen.

Posted at 17:28 Permalink

Friday, July 15, 2005

HTML: Persuading Internet Explorer to Do Widths Correctly

If you've ever created an HTML document with page margins and then included tables with widths specified which are narrower than the margins, you've probably noticed that Microsoft Internet Explorer has a very eccentric way of rendering such pages, different from any other present-day browser. As a concrete example, suppose you've defined page margins for the main body copy of your page with the following Cascading Style Sheet definition:
    div.bodycopy {
        margin-left: 15%;
        margin-right: 10%
and then wrapped the entire <body> of your document in this division style:
    <div class="bodycopy">
        . . .
Now suppose you'd like to include some tables in the document, each 85% of the width of the body copy, with a subtle light yellow background. You define the style of the table in CSS with:
    table.data {
	background-color: #FFFFD0;
    	margin-left: 10%;
	width: 85%;
and then include tables in this style:
    <table class="data">
        . . .
Now, all of this works precisely as you expected in Firefox, Netscape, Opera, and other browsers, and is validated without a quibble by the W3C XHTML and CSS checkers, but when you view the page with Internet Explorer, to your horror you discover that the tables are so wide that they extend off to the right of the body copy and may spill over the right side of the window! What's going on here?

It turns out that back in the days of Internet Explorer 4, Microsoft made different assumptions about the way widths, margins, and padding worked than those finally adopted in the W3C CSS standard. Because so many "Exploder Enhanced" pages had been created by the time the CSS standard was adopted, the default behaviour of Internet Explorer is the old, bad way, which results in the incorrect rendering of your page. "But wait," you say, "I included a DOCTYPE specifying the current version of XHTML. Shouldn't that direct the browser to render the page according to the standard?"

Well, it should, but in the case of Internet Explorer 6, it doesn't if you've begun your XHTML document, as you're supposed to, with an XML character set declaration like:

    <?xml version="1.0" encoding="iso-8859-1"?>
This, for some screwball reason, causes Explorer to ignore the DOCTYPE declaration which follows it and render the page in the justly named "quirks" mode of version 4 of Explorer. If you omit the character set declaration, then the validators will complain, default to UTF-8, and fail if the document contains a different character encoding.

You can, however, specify the character encoding to the satisfaction of the validators and standards compliant browsers by using the <meta> "http-equiv" gimmick to force an HTTP Content-Type header on the document by including a meta tag like the following somewhere in the document <head>:

    <meta http-equiv="Content-Type"
     content="text/html; charset=iso-8859-1" />
This suffices to specify the document's character set, but slips past Internet Explorer without triggering its eccentric interpretation of margins and widths; your tables will be properly rendered. I discovered this stratagem on page 336 of the O'Reilly JavaScript & DHTML Cookbook by Danny Goodman.

Posted at 16:19 Permalink

Strike Out Posted

I've just posted a document, Strike Out: Reading Unedited Text, which describes the technique I've adopted for reading unedited text such as postings on discussion boards, comments on web logs, and the like. The absence of an editor between the author and the eyes of the reader means that anybody with something to say can reach anybody inclined to read it, which is both the advantage and the problem with these new "unmediated media". Reading too much unedited text, particularly if you're doing so in search of nuggets of genuine wisdom or technical detail, can be depressing and result in scornful estimation of the intellect of the Internet community.

I'm not sure how this suggestion will be taken. I suspect that many will say, "How bloody obvious can you get?" Well, as simple-minded as it is, it took my simple mind more than decade to stumble onto the scheme, so perhaps others may benefit from having it explained with examples. I'm sure there will be some controversy over the implicit assumption that those who cannot spell or write grammatically have nothing to say, but since the "hate kiddies" who most vehemently advocate this viewpoint already hate everybody and everything anyway, the net increase in temperature is likely to be minimal.

Posted at 15:49 Permalink

Thursday, July 14, 2005

Reading List: Black Rednecks and White Liberals

Sowell, Thomas. Black Rednecks and White Liberals. San Francisco: Encounter Books, 2005. ISBN 1-59403-086-3.
One of the most pernicious calumnies directed at black intellectuals in the United States is that they are "not authentic"--that by speaking standard English, assimilating into the predominant culture, and seeing learning and hard work as the way to get ahead, they have somehow abandoned their roots in the ghetto culture. In the title essay in this collection, Thomas Sowell demonstrates persuasively that this so-called "black culture" owes its origins, in fact, not to anything blacks brought with them from Africa or developed in times of slavery, but rather to a white culture which immigrants to the American South from marginal rural regions of Britain imported and perpetuated long after it had died out in the mother country. Members of this culture were called "rednecks" and "crackers" in Britain long before they arrived in America, and they proceeded to install this dysfunctional culture in much of the rural South. Blacks arriving from Africa, stripped of their own culture, were immersed into this milieu, and predictably absorbed the central values and characteristics of the white redneck culture, right down to patterns of speech which can be traced back to the Scotland, Wales, and Ulster of the 17th century. Interestingly, free blacks in the North never adopted this culture, and were often well integrated into the community until the massive northward migration of redneck blacks (and whites) from the South spawned racial prejudice against all blacks. While only 1/3 of U.S. whites lived in the South, 90% of blacks did, and hence the redneck culture which was strongly diluted as southern whites came to the northern cities, was transplanted whole as blacks arrived in the north and were concentrated in ghetto communities.

What makes this more than an anthropological and historical footnote is, that as Sowell describes, the redneck culture does not work very well--travellers in the areas of Britain it once dominated and in the early American South described the gratuitous violence, indolence, disdain for learning, and a host of other characteristics still manifest in the ghetto culture today. This culture is alien to the blacks who it mostly now afflicts, and is nothing to be proud of. Scotland, for example, largely eradicated the redneck culture, and became known for learning and enterprise; it is this example, Sowell suggests, that blacks could profitably follow, rather than clinging to a bogus culture which was in fact brought to the U.S. by those who enslaved their ancestors.

Although the title essay is the most controversial and will doubtless generate the bulk of commentary, it is in fact only 62 pages in this book of 372 pages. The other essays discuss the experience of "middleman minorities" such as the Jews, Armenians in the Ottoman Empire, Lebanese in Africa, overseas Chinese, etc.; the actual global history of slavery, as a phenomenon in which people of all races, continents, and cultures have been both slaves and slaveowners; the history of ethnic German communities around the globe and whether the Nazi era was rooted in the German culture or an aberration; and forgotten success stories in black education in the century prior to the civil rights struggles of the mid 20th century. The book concludes with a chapter on how contemporary "visions" and agendas can warp the perception of history, discarding facts which don't fit and obscuring lessons from the past which can be vital in deciding what works and what doesn't in the real world. As with much of Sowell's work, there are extensive end notes (more than 60 pages, with 289 notes on the title essay alone) which contain substantial "meat" along with source citations; they're well worth reading over after the essays.

Posted at 00:06 Permalink

Monday, July 11, 2005

Do It Yourself: Dragon whose head follows you around the room

dragon_2005-07-11.jpg The Grand Illusions site has a free download of this cut-and-paste folded paper dragon whose head follows you as you move around the room. Here's the one I made--the printable image is in colour, but I don't have a colour printer. I found that it took a while before my brain blanked out its knowledge of the three dimensional structure and saw the illusion. It also helped to place the dragon above eye level in a location with a textured background behind it, such as curtains or window blinds. Once the illusion kicks in, it is striking; note that the dragon's head nods up and down as well as moves side to side. This is a simplified version of the concave mask illusion where a face seems to follow your motion.

Hat tip to Warren Bell on NRO's Corner.

Posted at 16:31 Permalink

Sunday, July 10, 2005

Your Sky: Live Comet and Asteroid Orbital Elements

The implementation of JPL Orbital Elements format in Your Sky permits importing current orbital elements for periodic comets and asteroids directly from the JPL DASTCOM database into Your Sky. I've put together the plumbing needed to do this, with the usual modicum of Cron jobs, shell scripts, Perl programs, duct tape, and chewing gum, so from now on the Your Sky object catalogues of periodic comets, asteroids by name, and asteroids by number will be updated daily from the current JPL database, bringing the latest newsflashes on these dribs and drabs of the solar system directly to your desktop.

When I was a kid, there were fewer than 2000 numbered asteroids. There are now almost 100,000, and more than 1600 comets with known orbital elements. There's a lot of stuff out there! Did you know there are heavenly bodies named 9007 James Bond, 13070 Seanconnery, and 16452 Goldfinger?

Turning to comets, on December 18th, 1680, Isaac Newton observed the Comet of 1680, now designated C/1680 V1. Where is it now? A single click, using its orbital elements as computed by Newton and contemporaries named Halley, Euler, Pingre, Encke, and Wolfers, shows the comet receding into the void, already more than 250 astronomical units from the Sun in the constellation of Auriga.

Posted at 00:27 Permalink

Friday, July 8, 2005

The War of the Worlds: New and Improved--Same as Before

What with the release of the current film incarnation of H. G. Wells's The War of the Worlds with the selfosophy dude in the starring rôle, traffic to the on-line edition of the original novel at this site has exploded in recent days. Notwithstanding its having opened during the Neuchâtel International Fantastic Film Festival, I'll confess to not having yet seen the flick, but interest in the story upon which it is based provided the perfect pretext to upgrade the on-line edition to 100% compliant XHTML 1.0 and clean up the formatting using CSS so it's more readable on the screen.

The new edition supplants its predecessor with no changes to file or fragment names; links--even "deep links" into the text--will not be broken by the transition to the new edition.

Posted at 00:50 Permalink

Wednesday, July 6, 2005

Reading List: Les mensonges de la Seconde Guerre mondiale

Faverjon, Philippe. Les mensonges de la Seconde Guerre mondiale. Paris: Perrin, 2004. ISBN 2-262-01949-5.
"In wartime," said Winston Churchill, "truth is so precious that she should always be attended by a bodyguard of lies." This book examines lies, big and small, variously motivated, made by the principal combatants in World War II, from the fabricated attack on a German radio station used as a pretext to launch the invasion of Poland which ignited the conflict, to conspiracy theories about the Yalta conference which sketched the map of postwar Europe as the war drew to a close. The nature of the lies discussed in the various chapters differs greatly--some are propaganda addressed to other countries, others intended to deceive domestic populations; some are strategic disinformation, while still others are delusions readily accepted by audiences who preferred them to the facts. Although most chapters end with a paragraph which sets the stage for the next, each is essentially a stand-alone essay which can be read on its own, and the book can be browsed in any order. The author is either (take your pick) scrupulous in his attention to historical accuracy or, (if you prefer) almost entirely in agreement with my own viewpoint on these matters. There is no "big message", philosophical or otherwise, here, nor any partisan agenda--this is simply a catalogue of deception in wartime based on well-documented historical examples which, translated into the context of current events, can aid in critical analysis of conventional wisdom and mass stampede media coverage of present-day conflicts.

Posted at 22:05 Permalink

Sunday, July 3, 2005

Your Sky Orbital Element Upgrade

With last week's transition of Your Sky to stateless operation having gone smoothly (at least no problems reported or evident in the log so far), I went ahead and installed a long-planned upgrade to the parser for the orbital elements of asteroids and comets these programs permit you to track and display in sky maps.

Almost everybody expresses these orbital elements in the same terms (although there are some differences, for example some specifying the semi-major axis distance for elliptical orbits while others prefer the perihelion distance, valid for parabolic and hyperbolic orbits as well, these quantities are easily mathematically transformed into one another), there are about as many ways of writing them on a page, or in a table, or as an item in a database, or other means of communication among people and computers as there are people who have ever found the need to do so. The IAU Minor Planet Center's Ephemeris Service, for example, provides orbital elements in a total of eighteen different formats, one of which I will confess as having brought into existence in a moment of youthful indiscretion.

In addition to these more or less well-defined computer-oriented ways of expressing orbital elements, a variety of sloppier formats used in the days when astronomical discoveries were reported by telegraph and teleprinter remain in use. My goal when implementing Your Sky was that, to the extent possible, one should be able to cut and paste orbital elements from E-mail announcements, newsgroup postings, Web sites, etc., and have them work with little or no fiddling. This is why the Your Sky orbital element documentation lists five different formats for orbital elements and, in fact, supports additional variants of those listed and permits sloppiness in column alignment and other fine points of formatting not discussed in the document.

These standards, if you can call them that, are, like everything else in the solar system, a moving target. In particular, the Minor Planet Center has revised its own syntax for cometary orbital elements, and the extremely useful (and freely available without a subscription) DASTCOM Small-Body Orbital Elements database from the Solar System Dynamics group at JPL has its own single-line elements format for asteroids and comets.

This update of Your Sky now parses all of these additional orbital element formats. To celebrate the imminent collision of the Deep Impact spacecraft with Comet 9P/Tempel 1, the following URLs will display the current position of the comet in the sky with the Your Sky virtual telescope, with orbital elements specified in:

I haven't yet added documentation and examples of the new formats to the Your Sky asteroid and comet tracking help page; I'll do that in a few days when I'm confident the new code is behaving well, at which time I'll integrate it into Solar System Live as well.

Posted at 21:30 Permalink

Friday, July 1, 2005

Reading List: Diary of an Early American Boy

Sloane, Eric. Diary of an Early American Boy. Mineola, NY: Dover, [1962] 2004. ISBN 0-486-43666-7.
In 1805, fifteen year old Noah Blake kept a diary of his life on a farm in New England. More than a century and a half later, artist, author, and collector of early American tools Eric Sloane discovered the diary and used it as the point of departure for this look at frontier life when the frontier was still in Connecticut. Young Noah was clearly maturing into a fine specimen of the taciturn Yankee farmer--much of the diary reads like:
21: A sour, foggy Sunday.
22: Heavy downpour, but good for the crops.
23: Second day of rain. Father went to work under cover at the mill.
24: Clear day. Worked in the fields. Some of the corn has washed away.
The laconic diary entries are spun into a fictionalised but plausible story of farm life focusing on the self-reliant lifestyle and the tools and techniques upon which it was founded. Noah Blake was atypical in being an only child at a time when large families were the norm; Sloane takes advantage of this in showing Noah learning all aspects of farm life directly from his father. The numerous detailed illustrations provide a delightful glimpse into the world of two centuries ago and an appreciation for the hard work and multitude of skills it took to make a living from the land in those days.

Posted at 22:55 Permalink