Cover; November 1998; Scientific American Magazine; by Staff Editor; 1 Page(s)

Table of Contents; November 1998; Scientific American Magazine; by Staff Editor; 2 Page(s)

From the Editors, including Masthead; November 1998; Scientific American Magazine; by Rennie; 1 Page(s)

Letters to the Editors; November 1998; Scientific American Magazine; by Staff Editors; 2 Page(s)

50, 100 and 150 Years Ago; November 1998; Scientific American Magazine; by Staff editor; 1 Page(s)

NOVEMBER 1948 CYBERNETICS--Cybernetics is a word invented to define a new field in science. It combines under one heading the study of what in a human context is sometimes loosely described as thinking and in engineering is known as control and communication. In other words, cybernetics attempts to find the common elements in the functioning of automatic machines and of the human nervous system, and to develop a theory which will cover the entire field of control and communication in machines and in living organisms. The word cybernetics is taken from the Greek kybernetes, meaning steersman. If the 17th and early 18th centuries were the age of clocks, and the latter 18th and 19th centuries the age of steam engines, the present time is the age of communication and control.

VIRUS SEX--Sex was once thought to be the exclusive possession of life¿s higher forms, yet simpler forms have been found to be possessed of it. Sexual reproduction is the coming together and exchanging of character factors of two parents in making a new individual. Experiments with viruses that attack bacteria showed that inside a bacterium, two or more ¿killed¿ (or mortally damaged) viruses can pool their undamaged parts to make whole individuals capable of reproducing themselves.

In Focus: Dogma Overturned; November 1998; Scientific American Magazine; by Gibbs; 2 Page(s)

Rats can do it. So can opossums, songbirds, marmosets-- why, even tree shrews. But every biology student is taught that humans cannot produce new neurons anywhere in their brains once they have matured. That is a limitation--damage from abuse, disease and injury never heals--but it is also an evolutionary advantage, because it means that memories, imprinted in webs of neurons, can persist undisturbed for a lifetime. Or so the theory has gone for more than a decade.

Now it appears that that fundamental dogma of medicine is wrong; at the very least, it is far too sweeping. Two neuroscientists, one American and one Swedish, have collected the first persuasive evidence that mature, even elderly, people do create additional neurons by the hundreds in at least one important part of the brain, a section of the hippocampus called the dentate gyrus. At press time, the paper was still under review for publication by Nature Medicine.

Inconstant Constants; November 1998; Scientific American Magazine; by Musser; 2 Page(s)

Of all the assumptions that undergird modern science, perhaps the most fundamental is the uniformity of nature. Although the universe is infinitely diverse, its basic workings appear to be the same everywhere. Otherwise, how could we ever hope to make sense of it? Historically, scientists presupposed uniformity on religious grounds. In this century, Albert Einstein encapsulated it in his principle of relativity. As geologists and astronomers peered far beyond the domain of common experience, they saw no sign that nature behaved any differently in the distant past or in deep space.

Until now. A team of astronomers led by John K. Webb of the University of New South Wales has found the first hint that the laws of physics were slightly different billions of years ago. "The evidence is a little flimsy," says Robert J. Scherrer of Ohio State University. "But if it¿s confirmed, it¿ll be the most startling discovery of the past 50 years."

Down Detection; November 1998; Scientific American Magazine; by Ezzell; 2 Page(s)

Adrugstore urine test indicates to a 38-year-old woman that she is pregnant. After examining her and taking her history, her gynecologist tells her that she is roughly 10 weeks into the pregnancy. Although the woman is elated, she is also worried about Down syndrome, a form of mental retardation caused by an extra copy of chromosome 21 that occurs more often in the offspring of women older than 35. She and her husband have decided that they would opt for abortion if they conceive a fetus with the disorder. Her doctor says blood tests can determine whether the fetus has Down syndrome but only between weeks 16 and 18 of gestation--during the second trimester. That means the woman might face an abortion in the fifth month, which is particularly traumatic because such late abortions usually involve inducing labor and delivering the fetus.

The above scenario occurs hundreds of thousands of times every year in the U.S. alone. But researchers are now evaluating whether a suite of blood tests-- one of them new--can be combined with a novel ultrasound technique to detect Down syndrome reliably in fetuses as early as 10 weeks after conception.

The "E. Coli" are Coming; November 1998; Scientific American Magazine; by Stix; 1 Page(s)

Social critics sometimes proclaim that microbes seem to have supplanted the Soviets as a dire threat to the American way of life. Headlines trumpet the perils of flesheating bacteria and the deadly bugs lurking in raw hamburger. Although the U.S. won the cold war, some new evidence suggests that unless we learn to live with them, the bugs may win the battle in the hot zone.

For the past couple of years, Stuart B. Levy of Tufts University has warned of the fallout from undue preoccupation with germ fighting. The proliferation of household products that kill or inhibit bacteria might be helping to create a generation of superbugs that can withstand the chemical onslaught from disinfectants and, in some cases, exhibit resistance to antibiotic drugs.

In Brief; November 1998; Scientific American Magazine; by Leutwyler; 3 Page(s)

Unforgettable? Using advanced functional magnetic resonance imaging (fMRI), two groups of scientists have captured the first images of memories being formed within the brain. Randy L. Buckner of Washington University and his colleagues at Harvard University and Massachusetts General Hospital measured brain activation in young adults as they completed verbal tasks. Later the subjects were asked which words they remembered. James B. Brewer and his colleagues at Stanford University conducted a similar investigation, asking subjects to recall photographs. In both studies, higher levels of activity in the prefrontal and parahippocampal cortices--regions long thought to be involved in encoding memory--corresponded with stronger memories.

Winding the Master Clock The big wheel keeps on turning all right, but not at the same speed. The earth¿s rotation is actually slowing down. Thus, on December 31 the U.S. Naval Observatory, working for the International Earth Rotation Service (IERS), will add a leap second to the Coordinated Universal Time, the basis for world timekeeping. It is the 22nd leap second added since 1972, when the IERS decided to let atomic clocks--accurate to within a billionth of a second a day--run independently of the earth, which as a clock is only good to about one thousandth of a second a day.

Anti Gravity: Lucky Laima; November 1998; Scientific American Magazine; by Mirsky; 1 Page(s)

A television show from the 1970s featured an exceedingly diminutive fellow in evening dress who informed his boss at the start of every episode as to the impending arrival of their guests by hollering, "The plane! The plane!" The recent achievement of another aircraft conjured up the image of that obstreperous raconteur, as perhaps only he would have been small enough to pilot it. His presence, however, would have defeated the flight¿s purpose: the first transatlantic crossing by an unmanned airplane.

The robotic plane, one of a fleet called Aerosondes, is two meters (six feet) long, has a three-meter wingspan and weighs about as much as Herve Villechaize, tipping the scales at a wispy 13 kilograms (29 pounds) or so, depending on how much of its eight liters (two gallons) of fuel is left. The product of an outfit called the Insitu Group in Bingen, Wash., in conjunction with the University of Washington and an Australian group, the Aerosonde, dubbed Laima, departed Newfoundland on August 20. Although it left from an airport at Bell Island, that site was a formality rather than a necessity. The plane actually took off from the top of a speeding car, a launch strategy usually reserved for forgotten bags of groceries.

Tool Time on Cactus Hill; November 1998; Scientific American Magazine; by Beardsley; 2 Page(s)

On a scorching Saturday in late August in southern Virginia, at the end of a dirt track leading through fields of corn and soybeans, archaeologist Michael F. Johnson sits in the shade of oak and hickory trees eating his packed lunch. Nearby, brightblue tarpaulins protect excavations that have brought Johnson here most weekends for the past several years.

The object of Johnson¿s passion is a dune of blown sand known as Cactus Hill. Between bites, Johnson is debating with visiting archaeologist Stuart J. Fiedel what the place was like 14,000 years ago. It must have been ideal for a summer camp, Johnson thinks. Facing north, it would have been cooled by winds coming off glaciers hundreds of miles distant. He offers me an inverted plastic bucket to sit on. The dune would have been dry, he continues, a welcome relief from the surrounding insect-infested bogs. The Nottoway River was at the time only a stone¿s throw away. There were lots of animals: mastodon, elk, bison, deer, perhaps moose and caribou.

By the Numbers: How Congress Voted on the Environment; November 1998; Scientific American Magazine; by Doyle; 2 Page(s)

One of the enduring anomalies of political life is that Americans overwhelmingly picture themselves as environmentalists while Congress often votes against environmentalist positions. The explanation for this discrepancy probably lies in several factors: public indifference to arcane but important legislative details; the influence of commercial interests, which make substantial campaign contributions to all parties; and principled opposition by conservative legislators to mandates from Washington.

To give the public more information on environmental voting, the League of Conservation Voters (LCV) was founded in 1970. The maps are based on LCV ratings of members of the 105th Congress through mid-September. In compiling the ratings, the LCV used a select list of 14 environmental measures considered by the Senate and 29 considered by the House. (Included in the latter is one declaration of co-sponsorship, in which members do not actually vote but express their viewpoint.) The measures chosen represent the consensus of more than two dozen environmental and health groups. These measures, in the words of the LCV, "presented Members of Congress with a real choice on protecting the environment and help distinguish which legislators are working for environmental protection." The LCV scores range from 0 to 100, where high scores represent pro-environmentalist positions.

Profile: Monstrous Moonshine is True; November 1998; Scientific American Magazine; by Gibbs; 2 Page(s)

Talking to Richard Borcherds about his work can be unnerving. It is not just the difficulty of trying to keep up with the intellect of someone who, at the age of 38, has already won the highest award in mathematics, a Fields Medal, made of solid gold and bearing a Latin inscription that urges him "to transcend human limitations and grasp the universe."

There is also the palpable unease of his movements. I arrive at his of- fice in a nondescript corner of the University of Cambridge precisely when he expected; I knock quietly on the door. Yet my entrance has completely flustered him. He begins pacing like a caged tiger and waving his arms at nothing in particular. He appears to have no idea what to do next. I offer myself a seat.

Patent Blunder; November 1998; Scientific American Magazine; by Zorpette; 1 Page(s)

Hours after American cruise missiles demolished a chemical plant in Sudan this past August, U.S. officials found themselves addressing Sudanese claims that the factory manufactured only pharmaceuticals and other beneficial compounds. The U.S., attempting to lend credence to its contention that the facility was producing chemical weapons, cited a soil sample obtained clandestinely a few yards from the plant this past June. The sample contained a chemical known by the acronym EMPTA, whose only practical, large-scale industrial use is in the manufacture of an extremely deadly nerve agent known as VX. The officials also insisted that Iraqi scientists had helped set up the VX operation at the Sudanese plant, a claim they said they confirmed by means of intercepted telephone conversations. Beyond those disclosures, however, the U.S. revealed little of the large, fragmented and incomplete mosaic of intelligence information that in all likelihood precipitated the site¿s selection for bombing.

This reticence may have been partly linked to an embarrassing fact: the heart of Iraq¿s recipe for VX may very well have come from the U.S. Patent and Trademark Office.

Rough Sailing for Smart Ships; November 1998; Scientific American Magazine; by Hayashi; 1 Page(s)

Three years ago the U.S. Navy commenced a bold plan for slashing costs while preparing its fleet for the next century. The program, dubbed "Smart Ship," called for a reduction in crew levels through increasingly computerized ships. Additional savings would be achieved by using commercial off-the-shelf products, such as Pentium-chip computers, instead of expensive custom parts to build the new automated systems. But Smart Ship has recently encountered rough waters. A major computer crash on board the first of the automated ships has led to harsh criticisms of the navy initiative, and the dispute has touched off ugly accusations that important technical decisions are being controlled by politics--not by engineering.

The controversy began when the USS Yorktown, a guided-missile cruiser that was the first to be outfitted with Smart Ship technology, suffered a widespread system failure off the coast of Virginia in September last year. After a crew member mistakenly entered a zero into the data field of an application, the computer system proceeded to divide another quantity by that zero. The operation caused a buffer overflow, in which data leak from a temporary storage space in memory, and the error eventually brought down the ship¿s propulsion system. The result: the Yorktown was dead in the water for more than two hours.

Shutting Down a Gene; November 1998; Scientific American Magazine; by Stix; 2 Page(s)

The idea seems simple and elegant. Turn off gene expression by blocking the action of the messenger RNA, which provides the essential information for assembling a protein. Antisense therapy, as it is called, could conceivably target a virus or a cancer cell with exquisite precision. But this biotechnology has followed the trend line for much of the rest of the industry. Initial hyperbole was followed by disillusionment and even abandonment of the technology by some developers. Finally, a more balanced sense of realism emerged about future prospects.

"There was tremendous optimism among scientists and investors that these were going to be the drugs of the 1990s and the new millennium," remarks Arthur M. Krieg, a professor of internal medicine at the University of Iowa and an editor of an antisense journal. "It became clear very rapidly that things were not that easy."

Little Bangs; November 1998; Scientific American Magazine; by Stix; 2 Page(s)

Getting enough force out of silicon micromachines for them to do a useful amount of work has always proved a nettlesome challenge. A few researchers have begun to obtain more bang for the micron by making silicon chips with tiny cavities, filling them with explosives or rocket propellant and setting them afire.

Micropyrotechnics, it is conjectured, may one day power or reorient satellites and pulse drugs through the skin. Coupling ignitable materials with microelectromechanics (MEMS)--the technology that fashions submillimeter, electrically driven machines through standard chip fabrication methods--has begun to advance beyond the concept stage in a few laboratories.

Cyber View; November 1998; Scientific American Magazine; by Wallich; 1 Page(s)

Help! Craig Furr, a six-yearold British boy with a brain tumor, wanted to go to Disney World before he died. After the trip, as his parents were checking out of the hotel, they noticed they¿d been charged $2,500 for chocolate chip cookies from room service. While they were arguing over the bill, a gang of kidney thieves kidnapped Craig and spirited him away through Disney World¿s tunnels. The kidnappers put a wig on his head (which was hairless from chemotherapy) and dressed him as a girl, but luckily, a sharpeyed security guard noticed Craig¿s oldfashioned side-lacing British shoes. The hotel, though, is suing Craig¿s parents for the $2,500, and unless they can get enough e-mail sent to santa@northpole. Org in the next month to win the Guinness Book of World Records¿s prize contest, they will lose their house!

You¿ve never gotten this particular appeal in your electronic in box, but odds are that you¿ve received--or sent--copies of at least some of the hundreds of urban legends circulating via the Internet. (In fact, this column was conceived when a Scientific American writer who shall remain nameless circulated the story of the $250 Neiman Marcus/Mrs. Fields/Waldorf- Astoria cookie recipe.) Temporary tattoos laced with LSD and strychnine, stolen kidneys, intimate encounters with gerbils, deadly computer viruses embedded in e-mail: the list goes on. Terry Chan of the Usenet discussion group alt.folklore.urban (AFU) maintains a file of more than 1,000 items of modern folklore, along with verdicts on their truth or falsity. You can read this FAQ (frequently asked questions) list or search for a verdict on a specific tale from www.urbanlegends.com and other sites.

Natural Oil Spills; November 1998; Scientific American Magazine; by MacDonald; 6 Page(s)

Beneath the Gulf of Mexico, to the south of Texas and Louisiana, tiny bubbles of oil and natural gas trickle upward through faulted marine sediments. Close to the seafloor, these hydrocarbons ooze past a final layer teeming with exotic deep-sea life before they seep into the ocean above. Buoyant, they rise through the water in tight, curving plumes, eventually reaching the surface. There the gas merges with the atmosphere, and the oil drifts downwind, evaporating, mixing with water and finally dispersing.

The best time to witness such a natural "oil spill" is in summer, when the Gulf stays flat calm for days at a time. In the middle of the afternoon, with the full heat of the tropical sun blazing off the sea, one can stand on the deck of a ship and watch broad ribbons of oil stretch toward the horizon. Cruising upwind along one of these slicks, one will notice that the sea takes on an unusual smoothness. The clarity of the water seems to increase, and the glare of the sun off the surface intensifies. Flying fish break from the bow waves and plunge into the water again almost without making a splash. Presently, the scent of fresh petroleum becomes evident--an odor that is quite distinct from the diesel fumes wafting from the ship--and one sees waxy patches floating on the water or clinging to the hull.

The Meteorite Hunter, Part I: The Day the Sands Caught Fire; November 1998; Scientific American Magazine; by Wynn, Shoemaker; 8 Page(s)

Imagine, for a moment, that you are standing in the deep desert, looking northwest in the evening twilight. The landscape is absolutely desolate: vast, shifting dunes of grayish sand stretch uninterrupted in all directions. Not a rock is to be seen, and the nearest other human being is 250 kilometers away. Although the sun has set, the air is still rather warm--50 degrees Celsius--and the remnant of the afternoon sandstorm is still stinging your back. The prevailing wind is blowing from the south, as it always does in the early spring.

Suddenly, your attention is caught by a bright light above the darkening horizon. First a spark, it quickly brightens and splits into at least four individual streaks. Within a few seconds it has become a searing flash. Your clothes burst into flames. The bright objects flit silently over your head, followed a moment later by a deafening crack. The ground heaves, and a blast wave flings you forward half the length of a football field. Behind you, sheets of incandescent fire erupt into the evening sky and white boulders come flying through the air. Some crash into the surrounding sand; others are engulfed by fire.

Meteorite Hunters Part II: The Search for Greenland's Mysterious Meteor; November 1998; Scientific American Magazine; by Gibbs; 8 Page(s)

The astonishing news came via satellite phone, at about 8 P.M., recalled astronomer Lars Lindberg Christensen. He, the four other Danes and the two Greenlanders on the expedition team had just finished a late dinner and were sitting in the communal dome tent, killing time. Time was gnawing back. For seven days, their search for any remnants of the Kangilia meteor had been halted as voices on the other end of the phone repeated variations on the same maddening message: "Stand by.... The helicopter is grounded in Kangerlussuaq by fog.... It¿s socked in at Paamiut.... It was forced back to Nuuk by the threat of whiteout . . .. Wait just a few more hours . . .." Meanwhile the campsite--built on snow that was not even supposed to be on the ice cap this far into Greenland¿s brief summer--was dissolving into an icy swamp. It was beyond time to move onto the dry, rocky peak of a nunatak and to get on with the hunt.

But now the voice on the phone had good news, incredible news. A television station in Nuuk was reporting that a game warden had found the meteorite. Sailing around the fractal labyrinth of island-dotted coves near Qeqertarsuatsiaat, about 60 kilometers (37 miles) west of camp, the ranger had seen four craters freshly carved from the coastal foothills. Dark rocks lay inside. "It was an intense moment," Christensen recounted the next morning. "Everyone was so excited. We must have burned an hour of satellite time tracking down the guy and arranging for him to guide us to the site." More good news followed: the weather system that had paralyzed the team was breaking up at last. The helicopter would pick them up shortly after dawn to go inspect the craters.

Glueballs; November 1998; Scientific American Magazine; by Close, Page; 6 Page(s)

There are no atoms of light. That is, photons do not attach to other photons, forming composite entities. But gluons, the particles that bind quarks--the basic units of matter--into objects such as protons, may indeed stick just to one another. Physicists call the resulting glob a glueball.

A glueball is thought to have a radius of 0.5 ¿ 10¿15 meter, less than that of a proton, and live for less time than light takes to cross a hydrogen atom. Ephemeral though these particles may seem, in the past year many physicists have become convinced that glueballs are showing up in experiments.

Evolution and the Origins of Disease; November 1998; Scientific American Magazine; by Nesse, Williams; 8 Page(s)

Thoughtful contemplation of the human body elicits awe--in equal measure with perplexity. The eye, for instance, has long been an object of wonder, with the clear, living tissue of the cornea curving just the right amount, the iris adjusting to brightness and the lens to distance, so that the optimal quantity of light focuses exactly on the surface of the retina. Admiration of such apparent perfection soon gives way, however, to consternation. Contrary to any sensible design, blood vessels and nerves traverse the inside of the retina, creating a blind spot at their point of exit.

The body is a bundle of such jarring contradictions. For each exquisite heart valve, we have a wisdom tooth. Strands of DNA direct the development of the 10 trillion cells that make up a human adult but then permit his or her steady deterioration and eventual death. Our immune system can identify and destroy a million kinds of foreign matter, yet many bacteria can still kill us. These contradictions make it appear as if the body was designed by a team of superb engineers with occasional interventions by Rube Goldberg.

Mating Strategies of Spiders; November 1998; Scientific American Magazine; by Preston-Mafham, Preston-Mafham; 6 Page(s)

Aspider¿s reproductive system bears little resemblance to that of any other group in the animal kingdom. From its head projects a pair of appendages called the pedipalps, sensory structures used primarily for tasting prospective prey. In male spiders the terminal segments of the "palps" are modified for introducing semen into a female.

The palpal organ, the basic copulatory structure of the male palp, can be likened to a simple bulb pipette. From a chamber that acts as a reservoir runs a narrow tube called the embolus with a pointed, open end through which semen passes. The male introduces the embolus into the female reproductive opening during mating. In higher families of spiders the palpal organ is surrounded by a complex set of sclerotized plates, hooks and spines. The females have simultaneously evolved a sclerotized structure, the epigyne, near the reproductive opening. The projections on the male palp will fit only into the epigyne of a female of the same species.

Simulating Water and the Molecules of Life; November 1998; Scientific American Magazine; by Gerstein, Levitt; 6 Page(s)

Water is cheap, if not free, in most places in the world. But during the summer of 1986, one of us (Levitt) spent half a million dollars on an amount of water that would scarcely wet the point of a pin. The money was not to buy the vanishingly small amount of water. Rather it was to pay for the roughly two weeks of processing time on a gigantic stateof- the-art supercomputer required to create a model of how the water affected the structure and movement of a particular protein.

The protein was bovine pancreatic trypsin inhibitor (BPTI), which is found in the pancreases of cattle. BPTI is a favorite subject of computer modelers simply because it is relatively small and therefore easier to study than most other proteins. It had been modeled before, by Martin Karplus of Harvard University and his colleagues in 1977, but only "in vacuo" (as if in a vacuum)--without any other molecules interacting with it. No one had visualized BPTI as it really exists in a living cell, with thousands of water molecules surrounding it.

100 Years of Magnetic Memories; November 1998; Scientific American Magazine; by Livingston; 6 Page(s)

Magnets store much of the world¿s information: data on computer disks, entertainment on video and audiotapes, messages on telephone answering machines and account information on the coated stripes of ATM and credit cards. All these different media preserve words, numbers, images and sounds as invisible patterns of north and south poles. The technology is magnetic recording, which celebrates its centennial this year.

In recent decades magnetic memories have had a profound influence on society. In the 1970s the Watergate tapes from the Oval Office provided the "smoking gun" that forced President Richard Nixon to resign. This year audiotapes that disclosed an improper relationship between President Bill Clinton and a former White House intern led to another executive scandal.

The Amateur Scientist; November 1998; Scientific American Magazine; by Carlson; 2 Page(s)

Rarely does an unexpected call from a federal agency make my day; typically it just signals trouble. But I was pleasantly surprised by one recent phone call from Washington, D.C., which informed me of a fascinating project to chart ocean currents. My source, a scientist from the U.S. Geological Survey, explained that the program involves free-floating buoys (called drifters) that transmit their position along with various measurements of the ocean's properties to land-bound investigators. Government researchers would also like to study U.S. coastal waters in this way, yet they don't want to cause pollution and can't afford to deploy an armada of expensive drifters. The coordinator of this program asked me whether amateurs, whose skills have been honed by tight budgets, might have some clever ideas.

So here's your chance to contribute to science. The object is to design an inexpensive instrument for monitoring the ocean close to shore--something that perhaps could be built for only a few hundred dollars. To get you drifting in the right direction, this column lays out the requirements and discusses some hardware that may help. But don't limit yourself to the ideas presented here. I'll forward the best solutions to the federal agencies involved and post them on the World Wide Web site of the Society for Amateur Scientists. The winning designs in this informal competition will also earn laurels by appearing in a forthcoming column.

Mathematical Recreations; November 1998; Scientific American Magazine; by Stewart; 2 Page(s)

Most card games begin with someone shuffling the deck. The aim of shuffling, of course, is to randomize the order in which the cards appear. If the cards are shuffled too perfectly, however, the results are far from random. Let¿s consider the familiar riffle shuffle, in which the deck is cut in two and the cards interlaced.

Suppose, for the sake of argument, that the deck has 10 cards, all the same suit, arranged in consecutive order with the ace at the top and card 10 at the bottom. Cut the deck between cards five and six and carefully riffle shuffle the halves. If the first card in the top half of the original deck ends up on top of the shuffled deck, the order becomes ace, 6, 2, 7, 3, 8, 4, 9, 5, 10. If the first card in the bottom half of the original deck ends up on top, the order becomes 6, ace, 7, 2, 8, 3, 9, 4, 10, 5. The first method is called an outshuffle, the second an in-shuffle.

Reviews; November 1998; Scientific American Magazine; by Livingston, staff editors; 4 Page(s)

I teach in a department of materials science and engineering, a subject that was not taught, at least under that name, when I went to college. When in response to questions at cocktail parties I reply that I teach materials science, I am met with uncomprehending stares. Although my field is today one of the most important and dynamic areas of intellectual inquiry, it remains unknown and mysterious to most. These three recent books attempt to make the evolving field of materials science accessible to nontechnical readers.

The early stages of civilization are commonly described in terms of materials-- the Stone Age, the Chalcolithic (Copper-Stone) Age, the Bronze Age and the Iron Age. Early humans relied on natural materials, but we learned over the millennia that fire could convert clays into pottery, ores into metals and sands into glass, and we developed an ever wider assortment of materials with which to form our utensils, decorations, tools and weapons. Progress remained slow, however, until the 17th century, when Robert Boyle articulated the modern concept of chemical elements. By the 19th century most of the 100-odd elements of the periodic table (some odder than others) had been identified, providing a solid basis for the Industrial Revolution. And today¿s technology, from computers and lasers to jet engines and space probes, has been based on 20th-century advances in materials science.

Commentary: Connections - Oops; November 1998; Scientific American Magazine; by Burke; 2 Page(s)

From time to time it gives me great pleasure to come across, and publicize, the name of somebody who never got the credit. In this case, peering through my optically pure reading glasses in the British Library, I spy the name of a person who, in the privacy of his later years, must have said at least once, "Oops." Chap called Chester Moor Hall. Who? Okay, try this one: John Dollond. Right! The guy who invented the optically pure achromatic lens in 1757? Nope. Hall did it, years before.

A nice guy, Hall--and like many such, he finishes last. Around 1729 he becomes convinced that it is possible to make a lens that will not give you all kinds of blurred, colored images. The bane of astronomers up to then, and the reason they are seeing things like "planets with ears" (Saturn). So by 1733 Hall sticks lenses of differing densities (flint and crown glass) together, and the different dispersions kind of cancel one another out. Bingo. Achromatic, no-color fringes, total clarity. He makes a couple of telescopes for friends, sticks the whole experiment in the closet and goes back to being a landowning magistrate in Essex. Never does anything about it. Even when he hears some other guy (name of Champness) fussing about having invented it before Dollond. For the news of Chester Moor Hall¿s work to get mentioned in a paper to the Royal Society (where it¿s then filed and forgotten) takes another 100 years. And then another 165 to get to me. Forefront of historical research I¿m not. But you already knew that.

Commentary: Wonders - Numbers: Prime or Choice?; November 1998; Scientific American Magazine; by Morrison; 2 Page(s)

The simplest infinity is the one already recognized by many a curious young girl or boy counting 1, 2, 3, 4. . .. My friend Carl Sagan recalled a Sunday long ago when at age six he had delighted in newfound counting skills. His father explained to him that there need be no end to the count. Why stop? Just add one more. Gung ho, the boy set out to write integers that very evening all the way up to a big--if finite--1,000! His father generously wrote on for the boy during the time lost to Carl¿s customary evening bath. Together father and son completed their kilocount by bedtime, an experience Carl never forgot.

Positive integers are an infinite family whose kinship is wonderfully intricate. Most integers can be generated by multiplying together enough smaller integers, called factors. Thus, the number 18 = 2 x 3 x 3. (But try 17!) Here a chemical metaphor arises: 18 is a molecule among numbers, a composite of three numberatoms, whereas 17 suggests a pure element, all one kind of atom. It is called a prime number and has as factors only itself and unity.