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Thursday, June 30, 2005

Happy Birthday Special Relativity

One hundred years ago today, June 30th, 1905, Albert Einstein's Special Relativity paper, Zur Elektrodynamik bewegter Körper (On the Electrodynamics of Moving Bodies) was received for publication by Annalen der Physik, and hence this is the date it bore when published on September 26th, 1905. His paper on photoelectricity, Über einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristishen Gesichtspunktfor, for which he was awarded the Nobel Prize in Physics for 1921 "for his services to theoretical physics and in particular for his discovery of the law of the photo-electric effect", had been published in the June 9th issue of the same journal. These papers, along with his explanation of Brownian motion (published July 18th), his doctoral dissertation on the size of molecules and determination of Avogadro's number (received August 19th, 1905, published February 8th, 1906), and his paper on the equivalence of mass and energy (published November 21st, 1905), Ist die Trägheit eines Körpers von seinem Energieeinhalt abhängig? (Does the Inertia of a Body Depend upon its Energy-Content?) which contains the concept, but not the actual equation "E=mc²", were the highlights of Einstein's miraculous year of 1905. All of these papers are collected in new English translations in the eponymous book, which is now available in paperback.

A detailed chronology of events in Einstein's life in 1905 has been published as part of the Einstein exhibit by the American Institute of Physics, along with a chronology of his entire life.

Posted at 14:30 Permalink

Grey List Experiment: Spam Grand Slam

For the last day and a half I've been experimenting with Jef Poskanzer's Graymilter mail filter. This filter, using a technique called "greylisting" originally described by Evan Harris in 2003, exploits the fact that most spam-sending robots do not fully implement SMTP--in particular, they fail to handle a transient failure status (450) and re-send the mail later as required by the protocol.

Grey listing exploits this failure to comply with the standard by issuing 450 failures to the first attempt by any IP address to send mail (unless it has been explicitly named in a white list). When a rejection is sent, the IP address is placed onto a list which, some time later (25 minutes by default), is added to a temporary white list and permitted to send mail. Any legitimate mail client will, then, after the initial rejection, eventually deliver the mail. Once on the provisional white list, connections from the client will be accepted for two days, so mail from regular correspondents will not be delayed.

I installed the grey list filter about 36 hours ago, and its impact has been dramatic. In the first full 24 hours it has been in production, the total number of spam messages received and discarded by Annoyance Filter has fallen from a mean of about 170 per day to fewer than 30. (Note that this total is the cumulative effect of both grey listing and the greeting and hello delays I implemented previously. A naïve calculation suggests that each accounts for about half of the reduction in spam, but to be sure the filters should be tested independently in isolation from one another.)

Reducing the raw volume of incoming spam, before filters, to about 30 messages a day represents a roll-back of the current state of the Internet slum to the situation about five years ago--here's a situation where regress is progress! The only downside of grey listing is the delay in receiving mail from new correspondents while their IP addresses percolate the the dynamic white list pending the next re-delivery attempt. I approach this philosophically--"It's only E-mail; who cares?" Looked at through these glasses ("If it mattered, they'd have sent a FAX"), filtering E-mail becomes a more tractable undertaking.

Posted at 00:08 Permalink

Wednesday, June 29, 2005

Single Point Failures

sp_2005-06-29.jpg Having spent more than six months transitioning Fourmilab over to a server farm architecture and, in the process, trying to eliminate as many single points of failure as possible, I'm even more than usually sensitive to unexpected single point failures in the real world. Last week, Switzerland experienced a doozy. If there's one thing you expect about Switzerland, it's that the trains run on time and, in fact, they almost always do. Last Wednesday, June 22nd, however, Switzerland experienced a nation-wide railroad failure which, for about three hours, brought every train in the country to a standstill. Now many people, including me, never even remotely imagined that such a thing could happen, but it did. Apparently, the combination of a lightning strike, two parallel circuits being taken offline for maintenance, and the general star architecture of the 15,000 volt main lines contributed to an outage which never could have happened in the age of steam. Here is an article in English with an early look at the circumstances--a comprehensive investigation is underway. Naturally, when this happened, I had a visitor from the other side of the country who, like the 200,000 people en-route when the trains ground to a halt, was stranded until the system came back up. Fortunately, he was able to catch the last train that night after power was restored. The very next day, a shorter outage brought the trains to a halt in this region, but not all across the country.

Violent thunderstorms are an almost daily occurrence this time of year, and their impact on electrical and telecommunication infrastructure are something one simply must ride out, but it's kind of startling that a single event can bring all the trains to a halt. It's as unimaginable as Swissair going bankrupt . . . oh, right. Anyway, last Monday, June 27th, another lightning strike took down all the electricity in the Canton of Neuchâtel. A strike on a 125,000 volt line (bottom headline) turned out the lights for the entire Canton, including Fourmilab. Power was restored to some regions within about 40 minutes, but the outage here was more than an hour. The Fourmilab Web site was degraded, but did not go down--while the main servers shut down, the "pathfinder" server, which is a re-purposed laptop which can run about three hours on its batteries, took over as a hot spare, and the network gear and load balancers, which can run for hours on their UPSes, continued to route requests to that machine. Since it is a 1 GHz single processor machine, it was hideously overloaded and response was very slow, it did continue to run and serviced DNS and mail requests normally until power was restored. I didn't intend the site to be able to ride out an hour long power outage, but it's nice to know it can.

I suppose the lesson from all this for practical engineering is that if you can't imagine a single point failure in a system, this may be due to your own lack of imagination, not the system's robustness and fault tolerance.

Posted at 22:23 Permalink

Reading List: Round Ireland with a Fridge

Hawks, Tony. Round Ireland with a Fridge. London: Ebury Press, 1998. ISBN 0-09-186777-0.
The author describes himself as "not, by nature" either a drinking or a betting man. Ireland, however, can have a way of changing those particular aspects of one's nature, and so it was that after a night about which little else was recalled, our hero found himself having made a hundred pound bet that he could hitch-hike entirely around the Republic of Ireland in one calendar month, accompanied the entire way by a refrigerator. A man, at a certain stage in his life, needs a goal, even if it is, as this epic quest was described by an Irish radio host, "A totally purposeless idea, but a damn fine one." And the result is this very funny book. Think about it; almost every fridge lives a life circumscribed by a corner of a kitchen--door opens--light goes on--door closes--light goes out (except when the vegetables are having one of their wild parties in the crisper--sssshhh--mustn't let the homeowner catch on). How singular and rare it is for a fridge to experience the freedom of the open road, to go surfing in the Atlantic (chapter 10), to be baptised with a Gaelic name that means "freedom", blessed by a Benedictine nun (chapter 14), be guest of honour at perhaps the first-ever fridge party at an Irish pub (chapter 21), and make a triumphal entry into Dublin amid an army of well-wishers consisting entirely of the author pulling it on a trolley, a radio reporter carrying a mop and an ice cube tray, and an elderly bagpiper (chapter 23). Tony Hawks points out one disadvantage of his profession I'd never thought of before. When one of those bizarre things with which his life and mine are filled comes to pass, and you're trying to explain something like, "No, you see there were squirrels loose in the passenger cabin of the 747", and you're asked the inevitable, "What are you, a comedian?", he has to answer, "Well, actually, as a matter of fact, I am."

A U.S. edition is now available.

Posted at 21:11 Permalink

Monday, June 27, 2005

Timeout from Spam

Junk mail is increasingly sent by hijacked "zombie" machines infected with virus and worm software and operated by remote control. These zombies connect to a list of victims and blast mail at them as quickly as possible. So quickly, in fact, that they often violate the SMTP standard in various ways. Common violations are failing to wait for the "220" greeting message from the mail transport agent, or sending other parts of the transaction without waiting for the handshake from the last command. Many mail transport agents permit this sloppiness (if they didn't, spammers wouldn't do it), but starting with version 8.13 Sendmail adds options to enforce the standard more strictly and thereby detect and discard junk mail.

The key facility in limiting spam is greet_pause, which allows delaying the greeting message for a specified time after accepting a connection. For details on configuring this feature, and the associated PIPELINING=0, see Jef Poskanzer's mail filtering pages. I tried the following configuration on my server:

#   Enable access database (required by greet_pause below)
#   Delay greeting message by 10 seconds to deter blind spammers
#   Sleep one second on all RCPTs after a bad one to deter
#   dictionary spams.  (This should be much longer than one second!)
define(`confBAD_RCPT_THROTTLE', `1')dnl
I added the following to /etc/mail/access to suppress the delay for connections from the local site:
# Don't delay greeting on mail from localhost or Fourmilab
GreetPause:localhost            0
GreetPause:193.8.230            0
Before making this change, I was averaging about 170 junk mail messages a day detected and discarded by Annoyance Filter; the ten second greeting pause reduced this to about 120 per day--an improvement, but less than I'd hoped for.

I then decided to raise the stakes, and the cost for spammers, by hammering in a 25 second delay between the HELO or EHLO from the sending client and the confirmation message. (I picked 25 seconds off the top of my head--I've not experimented with different settings.) This was done by hammering a sleep(25) call into the source code of srvrsmtp.c as follows (around line 2057 of version 8.13.3):

   gothello = true;
    /* print HELO response message */
    if (c->cmd_code != CMDEHLO)
        message("250 %s Hello %s, %s",
            MyHostName, CurSmtpClient, q);
Note that this delay affects connections from the local site as well--I send so little E-mail that it doesn't bother me, and this is just an experiment, so I decided not to complicate things by getting the access database into the loop at this stage.

So how did it work? Quite well, so far--in the five full days since I've implemented this change, the mean number of junk mail messages as measured by Annoyance Filter has dropped to about 80 per day--a reduction of more than 50%. The reduction in load on the server is much greater than this number suggests (although at this site, spam processing is a minor component of server load). In a single day, introduction of the delays caused a total of more than 2000 SMTP connections from spammers to be rejected or closed without completing a mail transaction; most of these are "dictionary spams", looking for valid E-mail addresses on your site and now frustrated, wasting as much time on the perpetrator's machine as they permit before timing out.

More importantly, introduction of the 25 second "Hello" delay seems to have blocked about 95% of the grossly offensive pornographic spam which coarsens one's online experience simply by watching it scroll down the mail log window, even though it is automatically discarded by Annoyance Filter. Senders of "chinese junk"--the spam which arrives in Asian character sets--appear to be more patient and are not deterred by the delay, but then their blithering is easily filtered by the character set indicator and in any case isn't offensive (well, it might be if I could read it, but I can't).

Some may worry about losing legitimate mail by enforcing standards more strictly. First of all, any mail sending host which complies with the SMTP timeout recommendations in section 5.3.2 of RFC 1123 will have no problems whatsoever with the total 35 second greeting and hello delay introduced here. Secondly, and this represents a change in my personal philosophy regarding E-mail, I couldn't care less. I am tired of having my life coarsened by watching disgusting rejected messages scroll down my screen, and repelled by how having my face rubbed constantly in the bottom of the barrel reduces my estimation of my fellow humans. So I'm changing my approach to E-mail from a "do no harm" approach--no valid message rejected--to "active measures"--no questionable message brought to my attention in any way. This means I will no longer watch the log of arriving messages, spend no more time training Annoyance Filter on new junk mail, and send junk mail detected by Thunderbird's Bayesian filter directly to the trash without logging.

If somebody I don't know wants to send me a message and be sure I get it, they should send a FAX, mail a letter, or use the feedback form. Folks with whom I regularly exchange E-mail are already white-listed and bypass all the filters. Universal E-mail was a utopian idea which, like most utopian schemes, has failed; in my estimation it is no longer worth wasting time trying to patch it up, but rather limit its impact by restricting it by blocking all offensive material, whatever the cost in false positives. That's what I'm doing, anyway.

Posted at 22:54 Permalink

Sunday, June 26, 2005

Your Sky Goes Stateless

After a month's experience running Solar System Live as a stateless CGI application, this week-end I cut over Your Sky to stateless operation. Even though it only generates a small volume of traffic compared to Earth and Moon Viewer, Your Sky is by far the most complicated of these interactive CGI applications, as it is implemented as three independent but interlinked server applications, each of which generates links to the others.

The stateless version eliminates the image cache used previously to return custom images to requesters and with it, all need for session persistence--a request processed by one server in the server farm may have the custom images it includes generated by any available server since all the state required to create the image is now embedded in the URL which requests it. If the transition to stateless operation goes smoothly for Your Sky, I'll look at cutting over Earth and Moon Viewer in a week or two.

As with Solar System Live, the new version of Your Sky generates 100% compatible (transitional) XHTML 1.0; not only is this the latest and greatest version of HTML, it is embedded within XML and can be parsed by any XML parser. All of the static support files for Your Sky were converted to XHTML 1.0 some time ago.

Posted at 23:24 Permalink

Friday, June 24, 2005

Reading List: Air Disaster, Vol. 3

Job, Macarthur. Air Disaster, Vol. 3. Fyshwick, Australia: Aerospace Publications, 1998. ISBN 1-875671-34-X.
In the early 1970s I worked for a company that sold remote batch computing services on UNIVAC mainframes. Our management visited Boeing headquarters in Seattle to pitch for some of their business (unlikely, as Boeing had their own computer service bureau at the time, but you never know unless you try). Part of the presentation focused on how reliable our service was, averaging better than 99.5% uptime. The Boeing data processing manager didn't seem too impressed with this. He asked, "When you came up here from San Francisco, did you fly on one of our airplanes?" "As a matter of fact, we did.", answered the president of our company. The Boeing guy then asked, "Well, how would you feel if I told you Boeing airplanes only crash about once every two hundred flights?" The meeting moved on to other topics; we never did get any business from Boeing.

Engineering is an art we learn from failure, and the aviation safety community is the gold standard when it comes to getting to the probable cause of a complicated disaster and defining achievable steps to prevent it from recurring. There is much for for practitioners of other branches of engineering to admire and learn from looking over the shoulders of their colleagues in air accident investigation, and Macarthur Job's superb Air Disaster series, of which this is the third volume (Vol. 1, Vol. 2) provides precisely such a viewpoint. Starting from the official accident reports, author Job and illustrator Matthew Tesch recreate the circumstances which led to each accident and the sometimes tortuous process through which investigators established what actually happened. The presentation is not remotely sensationalistic, yet much more readable than the dry prose of most official accident reports. If detail is required, Job and Tesch do not shrink from providing it; four pages of text and a detailed full page diagram on page 45 of this volume explain far more about the latching mechanism of the 747 cargo door than many people might think there is to know, but since you can't otherwise understand how the door of a United 747 outbound from Honolulu could have separated in flight, it's all there.

Reading the three volumes, which cover the jet age from the de Havilland Comet through the mid 1990s, provides an interesting view of the way in which assiduous investigation of anomalies and incremental fixes have made an inherently risky activity so safe that some these days seem more concerned with fingernail clippers than engine failure or mid-air collisions. Many of the accidents in the first two volumes were due to the machine breaking in some way or another, and one by one, they have basically been fixed to the extent that in this volume, the only hardware related accident is the 747 cargo door failure (in which nine passengers died, but 345 passengers and crew survived). The other dozen are problems due to the weather, human factors, and what computer folks call "user interface"--literally so in several cases of mode confusion and mismanagement of the increasingly automated flight decks of the latest generation of airliners. Anybody designing interfaces in which the user is expected to have a correct mental model of the operation of a complex, partially opaque system will find many lessons here, some learnt at tragic cost in an environment where the stakes are high and the margin of error small.

Posted at 23:05 Permalink

Strangelove Slide Rule: Nuclear Bomb Effects Computer

I've just posted an interactive Web edition of the Nuclear Bomb Effects Computer slide rule which accompanied the 1962 book The Effects of Nuclear Weapons. This is a project which has been on my "to do" list for a long time. Originally, I thought in terms of a JavaScript-based calculator but, as I describe in the document, was finally won over by the nearly forgotten advantages of slide rules and nomograms which let you see the whole range of possible inputs yielding a given solution and easily work inverse problems.

The result is a CGI server-based application which presents the results in the original form--on a replica of the slide rule set for the inputs specified numerically by the user. The instructions which accompanied the slide rule have been transcribed, with illustrations added which show how to read values from the various scales. The production notes explain how the original plastic slide rule was transmogrified into its present Web incarnation.

Those who prefer a physical slide rule will find downloadable images and directions for making their own.

Posted at 00:52 Permalink

Saturday, June 18, 2005

Reading List: Abduction

Mack, John E. Abduction. New York: Ballantine Books, [1994] 1995. ISBN 0-345-39300-7.
I started this book, as I recall, sometime around 1998, having picked it up to get a taste for the "original material" after reading C.D.B. Bryan's excellent Close Encounters of the Fourth Kind, describing an MIT conference on the alien abduction phenomenon. I made it most of the way through Abduction on the first attempt, but ran out of patience and steam about 100 pages from the finish line while reading the material "recovered" from "experiencer" Carlos, which is the literary equivalent of a Vulcan mind meld with a custard pudding. A mercifully brief excerpt with Mack's interpolations in parentheses goes as follows (p. 355).
Their bodies go from being the little white creatures they are to light. But when they become light, they first become like cores of light, like molten light. The appearance (of the core of light) is one of solidity. They change colors and a haze is projected around the (interior core which is centralized; surrounding this core in an immediate environment is a denser, tighter) haze (than its outer peripheries). The eyes are the last to go (as one perceives the process of the creatures disappearing into the light), and then they just kind of disappear or are absorbed into this. . . . We are or exist through our flesh, and they are or exist through whatever it is they are.
Got that? If not, there is much, much more along these lines in the extended babblings of this and a dozen other abductees, developed during the author's therapy sessions with them. Now, de mortuis nihil nisi bonum (Mack was killed in a traffic accident in 2004), and having won a Pulitzer Prize for his biography of T.E. Lawrence in addition to his career as a professor of psychiatry at the Harvard Medical School and founder of the psychiatry department at Cambridge Hospital, his credentials incline one to hear him out, however odd the message may seem to be.

One's mind, however, eventually summons up Thomas Jefferson's (possibly apocryphal) remark upon hearing of two Yale professors who investigated a meteor fall in Connecticut and pronounced it genuine, "Gentlemen, I would rather believe that two Yankee professors would lie than believe that stones fall from heaven." Well, nobody's accusing Professor Mack of lying, but the leap from the oh-wow, New Age accounts elicited by hypnotic regression and presented here, to the conclusion that they are the result of a genuine phenomenon of some kind, possibly contact with "another plane of reality" is an awfully big one, and simply wading through the source material proved more than I could stomach on my first attempt. So, the book went back on the unfinished shelf, where it continued to glare at me balefully until a few days ago when, looking for something to read, I exclaimed, "Hey, if I can make it through The Ghosts of Evolution, surely I can finish this one!" So I did, picking up from the bookmark I left where my first assault on the summit petered out.

In small enough doses, much of this material can be quite funny. This paperback edition includes two appendices added to address issues raised after the publication of the original hardcover. In the first of these (p. 390), Mack argues that the presence of a genuine phenomenon of some kind is strongly supported by ". . . the reports of the experiencers themselves. Although varied in some respects, these are so densely consistent as to defy conventional psychiatric explanations." Then, a mere three pages later, we are informed:

The aliens themselves seem able to change or disguise their form, and, as noted, may appear initially to the abductees as various kinds of animals, or even as ordinary human beings, as in Peter's case. But their shape-shifting abilities extend to their vehicles and to the environments they present to the abductees, which include, in this sample, a string of motorcycles (Dave), a forest and conference room (Catherine), images of Jesus in white robes (Jerry), and a soaring cathedral-like structure with stained glass windows (Sheila). One young woman, not written about in this book, recalled at age seven seeing a fifteen-foot kangaroo in a park, which turned out to be a small spacecraft.
Now that's "densely consistent"! One is also struck by how insipidly banal are the messages the supposed aliens deliver, which usually amount to New Age cerebral suds like "All is one", "Treat the Earth kindly", and the rest of the the stuff which appeals to those who are into these kinds of things in the first place. Occam's razor seems to glide much more smoothly over the supposition that we are dealing with seriously delusional people endowed with vivid imaginations than that these are "transformational" messages sent by superior beings to avert "planetary destruction" by "for-profit business corporations" (p. 365, Mack's words, not those of an abductee). Fifteen-foot kangaroo? Well, anyway, now this book can hop onto the dubious shelf in the basement and stop making me feel guilty! For a sceptical view of the abduction phenomenon, see Philip J. Klass's UFO Abductions: A Dangerous Game.

Posted at 23:40 Permalink

Thursday, June 16, 2005

Reading List: The Ghosts of Evolution

Barlow, Connie. The Ghosts of Evolution. New York: Basic Books, 2000. ISBN 0-465-00552-7.
Ponder the pit of the avocado; no, actually ponder it--hold it in your hand and get a sense of how big and heavy it is. Now consider that due to its toughness, slick surface, and being laced with toxins, it was meant to be swallowed whole and deposited far from the tree in the dung of the animal who gulped down the entire fruit, pit and all. Just imagine the size of the gullet (and internal tubing) that requires--what on Earth, or more precisely, given the avocado's range, what in the Americas served to disperse these seeds prior to the arrival of humans some 13,000 years ago?

The Western Hemisphere was, in fact, prior to the great extinction at the end of the Pleistocene, (coincident with the arrival of humans across the land bridge with Asia, and probably the result of their intensive hunting), home to a rich collection of megafauna: mammoths and mastodons, enormous ground sloths, camels, the original horses, and an armadillo as large as a bear, now all gone. Plants with fruit which doesn't seem to make any sense--which rots beneath the tree and isn't dispersed by any extant creature--may be the orphaned ecological partners of extinct species with which they co-evolved. Plants, particularly perennials and those which can reproduce clonally, evolve much more slowly than mammal and bird species, and may survive, albeit in a limited or spotty range, through secondary dispersers of their seeds (seed hoarders and predators, water, and gravity) long after the animal vectors their seeds evolved to employ have departed the scene. That is the fascinating premise of this book, which examines how enigmatic, apparently nonsensical fruit such as the osage orange, Kentucky coffee tree, honey locust, ginkgo, desert gourd, and others may be, figuratively, ripening their fruit every year waiting for the passing mastodon or megatherium which never arrives, some surviving because they are attractive, useful, and/or tasty to the talking apes who killed off the megafauna.

All of this is very interesting, and along the way one learns a great deal about the co-evolution of plants and their seed dispersal partners and predators--an endless arms race involving armour, chemical warfare (selective toxins and deterrents in pulp and seeds), stealth, and co-optation (burrs which hitch a ride on the fur of animals). However, this 250 page volume is basically an 85 page essay struggling to get out of the rambling, repetitious, self-indulgent, pretentious prose and unbridled speculations of the author, which results in a literary bolus as difficult to masticate as the seed pods of some of the plants described therein. This book desperately needed the attention of an editor ready to wield the red pencil and Basic Books, generally a quality publisher of popularisations of science, dropped the ball (or, perhaps I should say, spit out the seed) here. The organisation of the text is atrocious--we encounter the same material over and over, frequently see technical terms such as indehiscent used four or five times before they are first defined, only to then endure a half-dozen subsequent definitions of the same word (a brief glossary of botanical terms would be a great improvement), and on occasions botanical jargon is used apparently because it rolls so majestically off the tongue or lends authority to the account--which authority is sorely lacking. While there is serious science and well-documented, peer-reviewed evidence for anachronism in certain fruits, Barlow uses the concept as a launching pad for wild speculation in which any apparent lack of perfect adaptation between a plant and its present-day environment is taken as evidence for an extinct ecological partner.

One of many examples is the suggestion on p. 164 that the fact that the American holly tree produces spiny leaves well above the level of any current browser (deer here, not Internet Exploder or Netscrape!) is evidence it evolved to defend itself against much larger herbivores. Well, maybe, but it may just be that a tree lacks the means to precisely measure the distance from the ground, and those which err on the side of safety are more likely to survive. The discussion of evolution throughout is laced with teleological and anthropomorphic metaphors which will induce teeth-grinding among Darwinists audible across a large lecture hall.

At the start of chapter 8, vertebrate paleontologist Richard Tedford is quoted as saying, "Frankly, this is not really science. You haven't got a way of testing any of this. It's more metaphysics."--amen. The author tests the toxicity of ginkgo seeds by feeding them to squirrels in a park in New York City ("All the world seems in tune, on a spring afternoon . . ."), and the attractiveness of maggot-ridden overripe pawpaw fruit by leaving it outside her New Mexico trailer for frequent visitor Mrs. Foxie (you can't make up stuff like this) and, in the morning, it was gone! I recall a similar experiment from childhood involving milk, cookies, and flying reindeer; she does, admittedly, acknowledge that skunks or raccoons might have been responsible. There's an extended discourse on the possible merits of eating dirt, especially for pregnant women, then in the very next chapter the suggestion that the honey locust has "devolved" into the swamp locust, accompanied by an end note observing that a professional botanist expert in the genus considers this nonsense.

Don't get me wrong, there's plenty of interesting material here, and much to think about in the complex intertwined evolution of animals and plants, but this is a topic which deserves a more disciplined author and a better book.

Posted at 16:01 Permalink

Sunday, June 12, 2005

Reading List: Ball Lightning

Stenhoff, Mark. Ball Lightning. New York: Kluwer Academic / Plenum Publishers, 1999. ISBN 0-306-46150-1.
Reports of ball lightning--glowing spheres of light which persist for some number of seconds, usually associated with cloud to ground lightning strikes during thunderstorms, date back to the classical Greeks. Since 1838, when physicist and astronomer Dominique Arago published a survey of twenty reports of ball lightning, a long list of scientists, many eminent, have tried their hands at crafting a theory which might explain such an odd phenomenon yet, at the start of the twenty-first century ball lightning remains, as Arago said in 1854, "One of the most inexplicable problems of physics today."

Well, actually, ball lightning only poses problems to the physics of yesterday and today if it, you know, exists, and the evidence that it does is rather weak, as this book demonstrates. (Its author does come down in favour of the existence of ball lightning, and wrote the 1976 Nature paper which helped launched the modern study of the phenomenon.) As of the date this book was published, not a single unambiguous photograph, movie, or video recording of ball lightning was known to exist, and most of the "classic" photographs illustrated in chapter 9 are obvious fakes created by camera motion and double exposure. It is also difficult when dealing with reports by observers unacquainted with the relevant phenomena to sort out genuine ball lightning (if such exists) from other well-documented and understood effects such as corona discharges (St. Elmo's fire), that perennial favourite of UFO debunkers: ignis fatuus or swamp gas, and claims of damage caused by the passage of ball lightning or its explosive dissipation from those produced by conventional lightning strikes. See the author's re-casting of a lightning strike to a house which he personally investigated into "ball lightning language" on pp. 105-106 for an example of how such reports can originate.

Still, after sorting out the mis-identifications, hoaxes, and other dross, a body of reports remains, some by expert observers of atmospheric phenomena, which have a consistency not to be found, for example, in UFO reports. A number of observations of ball lightning within metallic aircraft fuselages are almost identical and pose a formidable challenge to most models. The absence of unambiguous evidence has not in any way deterred the theoretical enterprise, and chapters 11-13 survey models based on, among other mechanisms, heated air, self-confining plasma vortices and spheroids, radial charge separation, chemical reactions and combustion, microwave excitation of metastable molecules of atmospheric gases, nuclear fusion and the production of unstable isotopes of oxygen and nitrogen, focusing of cosmic rays, antimatter meteorites, and microscopic black holes. One does not get the sense of this converging upon a consensus. Among the dubious theories, there are some odd claims of experimental results such as the production of self-sustaining plasma balls by placing a short burning candle in a kitchen microwave oven (didn't work for me, anyway--if you must try it yourself, please use common sense and be careful), and reports of producing ball lightning sustained by fusion of deuterium in atmospheric water vapour by short circuiting a 200 tonne submarine accumulator battery. (Don't try this one at home, kids!)

The book concludes with the hope that with increasing interest in ball lightning, as evidenced by conferences such as the International Symposia on Ball Lightning, and additional effort in collecting and investigating reports, this centuries-old puzzle may be resolved within this decade. I'm not so sure--the UFO precedent does not incline one to optimism. For those motivated to pursue the matter further, a bibliography of more than 75 pages and 2400 citations is included.

Posted at 16:36 Permalink

Wednesday, June 8, 2005

Reading List: Tom Swift and His Airship

Appleton, Victor. Tom Swift and His Airship. Bedford, MA: Applewood Books, [1910] 1992. ISBN 1-55709-177-3.
Following his adventures on land and lake, in this third volume of the Tom Swift series, our hero takes to the air in his hybrid dirigible/airplane, the Red Cloud. (When this book was written, within a decade of the Wright Brothers' first flight, "airship" referred to any flying craft, lighter or heavier than air.) Along the way he survives a forest fire, thunderstorm, flying bullets, false accusation of a crime, and an irritable schoolmarm not amused by having an airship crash into her girls' school, and solves the crime, bags the perpetrators, and clears his good name. Bless my seltzer bottle--never get on the wrong side of Mr. Wakefield Damon!

Apart from the arm-waving about new inventions which is the prerogative of the science fiction writer, Victor Appleton is generally quite careful about the technical details--All American Boys in the early 20th century knew their machinery and would be all over a scribbler who didn't understand how a carburetor worked! Here, however, he misunderstands lighter than air flight. He describes the Red Cloud as supported by a rigid aluminium gas container filled with "a secret gas, made partly of hydrogen, being very light and powerful". But since the only thing that matters in generating lift is the weight of the air displaced compared to the weight of the gas displacing it, and since hydrogen is the lightest of elements (can't have fewer than one proton, mate!), then any mixture of hydrogen with anything else would have less lift than hydrogen alone. (You might mix hydrogen with helium to obtain a nonflammable gas lighter than pure helium--something suggested by Arthur C. Clarke a few years ago--but here Tom's secret gas is claimed to have more lift than hydrogen, and the question of flammability is never raised. Also, the gas is produced on demand by a "gas generator". That rules out helium as a component, as it is far too noble to form compounds.) Later, Tom increases the lift on the ship by raising the pressure in the gas cells: "when an increased pressure of the vapor was used the ship was almost as buoyant as before" (chapter 21). But increasing the pressure of any gas in a fixed volume cell reduces the lift, as it increases the weight of the gas within without displacing any additional air. One could make this work by assuming a gas cell with a flexible bladder which permitted the volume occupied by the lift gas to expand and contract as desired, the rest being filled with ambient air, but even then the pressure of the lift gas would not increase, but simply stay the same as atmospheric pressure as more air was displaced. Feel free to berate me for belabouring such a minor technical quibble in a 95 year old story, but I figure that Tom Swift fans probably, like myself, enjoy working out this kind of stuff. The fact that this is only such item I noticed is a testament to the extent Appleton sweated the details.

I read the electronic edition of this novel published in the Tom Swift and His Pocket Library collection at this site on my PalmOS PDA in random moments of downtime over a month or so. I've posted an updated electronic edition which corrects typographical errors I spotted while reading the yarn.

Posted at 23:57 Permalink

Saturday, June 4, 2005

Reading List: Hadrian the Seventh

Rolfe, Fr. Hadrian the Seventh. New York: New York Review Books, [1904] 2001. ISBN 0-940322-62-5.
This is a masterpiece of eccentricity. The author, whose full name is Frederick William Serafino Austin Lewis Mary Rolfe, deliberately abbreviated his name to "Fr." not just in the interest of concision, but so it might be mistaken for "Father" and the book deemed the work of a Catholic priest. (Rolfe also used the name "Baron Corvo" and affected a coat of arms with a raven.) Having twice himself failed in aspirations to the priesthood, in this novel the protagonist, transparently based upon the author, finds himself, through a sequence of events straining even the omnipotence of the Holy Spirit, vaulted from the humble estate of debt-ridden English hack writer directly to the papacy, taking the name Hadrian the Seventh in honour of Hadrian IV, the first, last, and only English pope to date.

Installed on the throne of Saint Peter, Hadrian quickly moves to remedy the discrepancies his erstwhile humble life has caused to him to perceive between the mission of the Church and the policies of its hierarchy. Dodging intrigue from all sides, and wielding his intellect, wit, and cunning along with papal authority, he quickly becomes what now would be called a "media pope" and a major influence on the world political stage, which he remakes along lines which, however alien and ironic they may seem today, might have been better than what actually happened a decade after this novel was published in 1904.

Rolfe, like Hadrian, is an "artificer in verbal expression", and his neologisms and eccentric spelling ("saxificous head of the Medoysa") and Greek and Latin phrases--rarely translated--sprinkle the text. Rolfe/Hadrian doesn't think too highly of the Irish, the French, Socialists, the press, and churchmen who believe their mission is building cathedrals and accumulating treasure rather than saving souls, and he skewers these and other targets on every occasion--if such barbs irritate you, you will find plenty here at which to take offence. The prose is simply beautiful, and thought provoking as well as funny. The international politics of a century ago figures in the story, and if you're not familiar with that now rather obscure era, you may wish to refresh your memory as to principal players and stakes in the Great Game of that epoch.

Posted at 22:31 Permalink

Friday, June 3, 2005

Tom Swift in the Caves of Ice Now Online

The eighth episode in the Tom Swift saga, Tom Swift in the Caves of Ice, is now posted in the Tom Swift and His Pocket Library archive. As usual, HTML, PDF, PDA eReader, and plain ASCII text editions suitable for reading off- or online are available.

Posted at 22:45 Permalink