Scientific American Magazine
Cover; March 1998; Scientific American Magazine; by Staff Editor; 1 Page(s)
Table of Contents; March 1998; Scientific American Magazine; by Staff Editor; 2 Page(s)
From the Editors; March 1998; Scientific American Magazine; by Rennie; 1 Page(s)
Computer scientists (and maybe a few frustrated directors) have speculated about replacing human actors with digitally synthesized performers. Special effects have become so important to films, why not clear the set altogether? In theory, "synthespians" can do anything a script requires, from professing love to singing an aria to stomping on a skyscraper. They can combine the best features of a dozen mortals: care for a leading lady with the smile of Julia Roberts, the eyes of Isabella Rossellini and the cheekbones of Rita Hayworth? The current movie Titanic features computer-generated people moving on deck, but--sorry, kid, don't call us, we'll call you--their veneer of realism cracks under scrutiny. Still, it won't be long before somebody from central (processing unit) casting is ready for his or her close-up.
For the latest episode of Scientific American Frontiers, host Alan Alda lent his form and voice to an attempt to create a "Digital Alan." He was a fitting choice for this new medium, given that he is already a veteran of film, television and the stage. The process and results are described on pages 68 and 69 of this issue and on Frontiers (check your local listings for time and channel). Remarkable though Digital Alan is, I don't think he'll be stealing any roles from the real thing. Real talent is never obsolete: performance is all about expressing humanity.
Letters to the Editors; March 1998; Scientific American Magazine; by Staff Editor; 1 Page(s)
In the November 1997 "Anti Gravity" column, Steve Mirsky reports on the persistent stereotyping of scientists in our culture ["The Big Picture," News and Analysis]. One need only look at popular culture to see why. Without exception, scientists and "smart kids" are portrayed in movies and on television as weird, unsocial and, of course, wearing glasses (and a bow tie if male).
Mirsky mentions Nerdkids trading cards as one of several efforts to counteract this trend, but the cards miss the mark by an obvious mile. One program not mentioned is Science-by-Mail, run by the Museum of Science in Boston. This program provides a way to connect kids with real scientists who act as mentors. Science-by-Mail should help change perceptions of what scientists are really like.
50, 100 And 150 Years Ago; March 1998; Scientific American Magazine; by Staff Editor; 1 Page(s)
MARCH 1948 RADIO TAKES OVER--While post-war radio has not been all it was quacked up to be, FM and Television are two signifi- cant developments on the horizon. Television is still in its early stages of development and is so expensive as to be in the luxury class, but FM is now coming into its own. One largescale dealer is now advertising a portable model FM-AM receiver for $54.95 [about $400 in 1998 dollars], which brings this kind of radio reception down to the prices the average man can afford to pay.
MARCH 1898 STEEL AND PROGRESS--Sir Henry Bessemer, the inventor and metallurgist, died in London, March 14. The death of this great man reminds us of the importance of cheap, highquality Bessemer steel to the world, revolutionizing, as it did, many vast industries. In October, 1855, he took out a patent embodying his idea of rendering cast iron malleable by the introduction of atmospheric air into the fluid metal to remove carbon. In the fiftieth anniversary issue of Scientific American [ July 1896], the readers of our journal wisely put themselves on record as considering the Bessemer process the greatest invention of the last fifty years.
In Focus: Digital Dilemma; March 1998; Scientific American Magazine; by Eisenberg; 2 Page(s)
Convergence--the industry jargon for the merger of television and the personal computer into one interactive appliance--is upon us. With the advent of digital television (DTV), the commingling seems inevitable: DTV¿s enormous bandwidth, or line capacity, permits both television reception and connection to the Internet, which the existing broadcast format cannot handle. Yet the form of the coming merger is still up in the air. Whether it will be TV-centric or accommodating to PC users depends on behind- the-scenes business decisions on transmission standards that will play out in the coming months.
DTV¿s rollout begins in November, only 18 months after the Federal Communications Commission lent each of the nation¿s TV stations a second channel based on pledges to broadcast some high-definition programming. Most of the new channels lie within the UHF band (numbers 14 to 59); existing channels are to be given back once the DTV transition is complete.
Glow in the Dark; March 1998; Scientific American Magazine; by Musser; 1 Page(s)
Modern theories of the universe begin with the simplest of observations: the night sky looks dark. The darkness implies that the universe is not infinitely old, as scientists once thought. If it were, starlight would already have seeped into all corners of space, and we would see a hot, uniform glow across the sky. This insight is known as Olbers¿s paradox, after the 19th-century German astronomer Wilhelm Olbers.
Some kinds of light, however, have had enough time to suffuse space. The famous cosmic microwave background radiation, considered to be the definitive proof of the big bang, fills the sky. Now astronomers say they have found a second, younger background. It is thought to be the first look at a previously unseen period of the universe--between the release of the microwave background and the formation of the earliest known galaxies, about a billion years later. "We¿re really completing the resolution of Olbers¿s paradox," said Princeton University astronomer Michael S. Vogeley, one of the researchers who announced their findings at the American Astronomical Society meeting in January.
Unsound Reasoning; March 1998; Scientific American Magazine; by Harby; 2 Page(s)
At a recent conference on music and human adaptation at Virginia Tech, physicist John W. Coltman demonstrated what he first described in the early 1970s. After asking the attendees to divert their eyes, he played the same tune twice on the flute. He then asked whether anyone heard any difference between the two performances. No one spoke up; the two were virtually indistinguishable.
Then Coltman revealed his trick. The first time he performed the tune, he played it on a simple side-blown flute made of lightweight cherry wood. The second time he used a flute of identical design, except for one detail: it was made of concrete.
In Brief; March 1998; Scientific American Magazine; by Leutwyler; 3 Page(s)
Iron Tooth One of the oldest professions may be dentistry. Indeed, French researchers recently found a wrought-iron dental implant-- in the upper right gum of a man¿s remains--in a Gallo-Roman necropolis dating to the first or second century A.D. Because the implant and the socket match perfectly and the iron and bone mesh, Eric Crub¿zy of Toulouse University and his colleagues conclude that the implant¿s maker used the original tooth as a model and hammered in the replacement. Ouch.
E-Test for Eyes Computer screens cause tremendous eyestrain. To read fuzzy, pixelated letters, our eyes must refocus some 15,000 to 20,000 times during the average workday, estimates Erik L. Nilsen of Lewis and Clark College. But a solution may be on the way. Nilsen has found that if you measure for eyeglass prescriptions using an on-screen eye test, as opposed to the printed E variety, you can minimize some of the eyestrain that screens cause.
Anti Gravity: Urine the Money; March 1998; Scientific American Magazine; by Mirsky; 1 Page(s)
Time was that the only consequence of drugs in urine was the confiscation of Olympic medals. Now, however, researchers have coaxed lab mice to produce a valuable pharmaceutical agent and in a way that makes it easy to harvest and to purify. Thanks to science that definitely qualifies as being of the "gee whiz" variety, the mice produce the drug in their bladders and simply turn it over to interested parties when they urinate.
Transgenic animals that can produce pharmaceutical agents have been in the works for years, but the bioreactor organ of choice has been the mammary gland--useful drugs derived from animal milk are now in human clinical trials. The idea for trying the same with urine started when Tung- Tien Sun of New York University Medical School published a paper in 1995 describing genes for proteins, called uroplakins, that get expressed only in the bladder. These uroplakins mesh together and probably have a role in maintaining a tidy lining, a highly desirable feature in a bladder.
You See Brawny; I See Scrawny; March 1998; Scientific American Magazine; by Zorpette; 2 Page(s)
Iam happy with my body. I lift weights about three times a week and also skate, swim and run, and I make a show of eschewing the fatty, nutritionally bankrupt confections served at Scientific American¿s editorial meetings.
But I can¿t call myself a bodybuilder, because I don¿t have the requisite rocky ridges, lithoid lumps and spaghettiveined bulges upon which to gaze lovingly in a mirror. And even if I had all those things, I¿m no longer sure that I¿d see them. Apparently, as some in the muscled class stare into the looking glass, they see not thermonuclear thews but rather skin and bones.
Catching the Rays; March 1998; Scientific American Magazine; by Beardsley; 2 Page(s)
Essentially all of life is built from chemicals assembled with energy from the sun--directly through photosynthesis or indirectly via plant-derived fuel. Researchers at Arizona State University now believe they have succeeded in creating microscopic, solar-biological power plants that operate by a process modeled on photosynthesis. The investigators accomplished the long-sought feat in cell-like structures using only synthetic chemicals.
The work in Arizona employs water suspensions of liposomes--microscopic, hollow spheres with double-layered lipid walls. Liposome walls are in many ways like cell membranes, and by adding specific complex compounds to those walls, researchers, including Gali Steinberg- Yfrach, Ana L. Moore, Devens Gust and Thomas A. Moore, have made liposomes that act like the photosynthetic membranes inside plant cells. The minute vesicles first capture the energy from sunlight electrochemically; then they use it before it leaks away to generate ATP, a high-energy compound that cells employ as energy currency.
By The Numbers: Languages, Disappearing and Dead; March 1998; Scientific American Magazine; by Doyle; 1 Page(s)
The death of languages has been repeated many times in history. Localized disasters such as great floods or warfare have played a part, but in the modern era the spread of Europeans and their diseases has greatly accelerated the destruction. Local languages may be overpowered by a metropolitan language, thus increasing the pressure to neglect the ancestral tongue in favor of the new one, which is seen as the key to prospering in the dominant culture. Children may be forbidden to use their mother tongue in the classroom, as has occurred to many groups, including the Welsh and Aboriginal Australians. Speakers of minority languages have been forcibly relocated and combined with speakers of other languages, as happened when Africans were brought to the Americas as slaves. Practices such as these have made Native American languages the most imperiled of any on the earth.
The death of a language is not only a tragedy for those directly involved but also an irretrievable cultural loss for the world. Through language, each culture expresses a unique worldview. Thus, any effort to preserve linguistic variety implies a deep respect for the positive values of other cultures. For these reasons, the United Nations Educational, Scientific and Cultural Organization (UNESCO) has taken an interest in the preservation of endangered languages and in 1996 published the Atlas of the World¿s Languages in Danger of Disappearing, which is the primary source of the map depicted here.
Profile: Undressing the Emperor; March 1998; Scientific American Magazine; by Mukerjee; 2 Page(s)
I¿m not modest," concedes Alan Sokal, professor of physics at New York University, with a grin. "My parody is hilarious!" Two years ago his nonsensical article on the "hermeneutics of quantum gravity" appeared in the journal Social Text, only to be exposed by the author as a hoax. The Sokal "affair"-- his detractors prefer "stunt"-- highlighted misuses of scientific ideas by nonscientists, provoking front-page articles in the New York Times, the International Herald Tribune, the London Observer and Le Monde and a series of debates on university campuses. Sokal has now upped the ante by publishing, with physicist Jean Bricmont of Catholic University of Louvain in Belgium, a dissection of what he calls "sloppy thinking" on the part of postmodernists, social constructivists, cognitive relativists and sundry other "-ists."
The book, Imposteures Intellectuelles, is in French and primarily targets French thinkers, besides some English and American ones. (An English version is to appear later this year.) It made the best-seller lists in France--"French people take their intellectuals seriously," Sokal explains--and outraged his opponents. One more round of artillery had been discharged in the battle between scientists and their critics.
Closing the Book; March 1998; Scientific American Magazine; by Stix; 2 Page(s)
Last July, Edward W. Campion, a deputy editor at the New England Journal of Medicine, made a plea to kill studies that seek ties between power-line electromagnetic fields and cancer. "The 18 years of research have produced considerable paranoia, but little insight and no prevention. It is time to stop wasting our research resources," Campion wrote.
The editorial accompanied a report in the journal of a large epidemiological study by the National Cancer Institute that showed "little evidence" that magnetic fields from high-voltage lines, household wiring or appliances can increase the risk of childhood leukemia. It also followed by eight months a National Research Council review of hundreds of studies that indicated that "the current body of evidence does not show that exposure to these fields presents a human health hazard."
Composite Sketch; March 1998; Scientific American Magazine; by Scott; 2 Page(s)
Apilot complained that the composite wing on a Stealth fighter plane seemed too flexible. His fears soon were realized: the $45-million aircraft shed that wing during an air show last September and plummeted to the ground. Not long after, singer John Denver died in the crash of a composite- construction homebuilt plane called a Long-EZ--the same type in which science writer James D. Gleick was gravely injured (and his son killed) when it crashed in New Jersey last December. Composites--which consist of a high-strength material, such as carbon fiber, that is impregnated with a resin and then cured--are lighter than the more traditional aluminum, are more easily formed and are often stronger. But compared with aluminum, which has been used in aircraft construction since the early 20th century, advanced composites are a recent technology, having been introduced in the 1970s. With relatively little experience with composites, how confident can engineers be about the lifespan and integrity of the material, which is being used more frequently in aircraft construction?
"Composites are so new we don¿t have a complete grasp of their durability," notes Chin-Teh Sun, an aeronautical and astronautical engineer at Purdue University who has extensively researched composites. What is known, he says, is that environmental factors such as ultraviolet light and moisture can change the materials¿ properties. And as is the case for any material, an excessive load can cause failure and damage. "But how long they will last nobody can tell you for sure," he adds.
Scene of the Crime; March 1998; Scientific American Magazine; by Goodman; 2 Page(s)
Roughly 12 years ago forensic technician Garold L. Gresham was investigating a woman¿s murder. There were no solid leads for detectives, except that the killer¿s method suggested that a man had committed the act. As Gresham sifted through the crime scene--identifying fibers and fingerprints and typing blood--he discovered minute, red flecks of a hard, shiny material near the body. Under a microscope, they looked like paint, but with a difference. Gresham noticed that they were slightly ridged across their surfaces, much like the natural contours on fingernails. He was looking at nail polish, but it wasn¿t the victim¿s. He alerted the police that in searching for a male suspect, they were probably barking up the wrong tree.
Today if Gresham, now an advisory scientist at the Idaho National Engineering and Environmental Laboratory, could revisit that crime scene, he would most likely just load those flecks into a new tool that he and his colleague Gary S. Groenewold are developing with the University of Montana and the National Institute of Justice: a secondary ion mass spectrometer (SIMS) gun. The device would blast the surface of the chips with large ions that behave like atomicsize jackhammers, prying molecules from the surface and capturing them for characterization. Not only would Gresham have been able to tell that his sample was nail polish, he could also have identified nonvolatile organic chemicals, such as the soap with which the suspect washed her hands or perhaps residue of the perfume she wore.
Fake it Before You Make it; March 1998; Scientific American Magazine; by Stix; 1 Page(s)
Manufacturers of the machine tools that make the parts for a Ford Explorer or a Honda Accord still often rely on trial and error to correct misalignments in a grinding wheel or cutting machine. "Typically, you just try one thing, and if it doesn¿t work you try something else," says William W. Pflager, manager of research and development for Landis Gardner, a machine tool supplier to the automotive industry. It may be enough to make a small adjustment to the wheel that grinds the cylindrical shape of the main bearing of an automobile¿s crankshaft. But the imprecision of this method can often lead to costly delays when the machine is working a part with a more complicated geometry.
Industry and government has created simulation software that may be able to anticipate how well a tool forms a part even before the machine is built--or else it can diagnose faults in machines in operation. Machining variation analysis (MVA) can simulate the workings of machine tools that move with five degrees of freedom (three spatial dimensions as well as rotation about two axes). MVA creates a model of a virtual part, along with divergences from design specifications for machining, grinding, assembly, placement of parts, or other processes.
Cyber View; March 1998; Scientific American Magazine; by Grossman; 1 Page(s)
On December 16, 1997, President Bill Clinton signed into law the No Electronic Theft (NET) Act. This cheerful piece of legislation makes it a federal crime to distribute or possess unauthorized electronic copies of copyrighted material valued over $1,000, even when no profit is involved. The bill defines three levels of violations, depending on the value of the work and the number of past offenses. Possession of 10 or more illegal electronic copies worth more than $2,500 could land you six years in prison and a $250,000 fine. "You¿d be better off going out and shooting somebody," quips David J. Farber, professor of telecommunications at the University of Pennsylvania. "The penalty is less."
Farber was also a leading signatory to a letter from the Association of Computing Machinery sent to President Clinton, asking him to veto the bill. The ACM¿s objections had to do with the potential for damaging free communication among scientists, because the bill does not contain traditional fair-use exemptions, such as those allowing photocopying by libraries and academic institutions or quotation for purposes of review or criticism, or first sale, which allows you to loan or sell a secondhand book.
The Bose-Einstein Condensate; March 1998; Scientific American Magazine; by Cornell, Wieman; 6 Page(s)
In June 1995 our research group at the Joint Institute for Laboratory Astrophysics (now called JILA) in Boulder, Colo., succeeded in creating a minuscule but marvelous droplet. By cooling 2,000 rubidium atoms to a temperature less than 100 billionths of a degree above absolute zero (100 billionths of a degree kelvin), we caused the atoms to lose for a full 10 seconds their individual identities and behave as though they were a single "superatom." The atoms¿ physical properties, such as their motions, became identical to one another. This Bose-Einstein condensate (BEC), the first observed in a gas, can be thought of as the matter counterpart of the laser--except that in the condensate it is atoms, rather than photons, that dance in perfect unison.
Our short-lived, gelid sample was the experimental realization of a theoretical construct that has intrigued scientists ever since it was predicted some 73 years ago by the work of physicists Albert Einstein and Satyendra Nath Bose. At ordinary temperatures, the atoms of a gas are scattered throughout the container holding them. Some have high energies (high speeds); others have low ones. Expanding on Bose¿s work, Einstein showed that if a sample of atoms were cooled sufficiently, a large fraction of them would settle into the single lowest possible energy state in the container. In mathematical terms, their individual wave equations--which describe such physical characteristics of an atom as its position and velocity--would in effect merge, and each atom would become indistinguishable from any other
The Challenge of Antibiotic Resistance; March 1998; Scientific American Magazine; by Levy; 8 Page(s)
Last year an event doctors had been fearing finally occurred. In three geographically separate patients, an often deadly bacterium, Staphylococcus aureus, responded poorly to a once reliable antidote--the antibiotic vancomycin. Fortunately, in those patients, the staph microbe remained susceptible to other drugs and was eradicated. But the appearance of S. aureus not readily cleared by vancomycin foreshadows trouble.
Worldwide, many strains of S. aureus are already resistant to all antibiotics except vancomycin. Emergence of forms lacking sensitivity to vancomycin signifies that variants untreatable by every known antibiotic are on their way. S. aureus, a major cause of hospital-acquired infections, has thus moved one step closer to becoming an unstoppable killer.
Nanolasers; March 1998; Scientific American Magazine; by Gourley; 6 Page(s)
For decades, silicon transistors have become smaller and smaller, allowing the fabrication of tiny but powerful chips. Less well known is the parallel revolution of semiconductor lasers. Recently researchers have shrunk some of the dimensions of such devices to an astonishing scale of nanometers (billionths of meters), even smaller than the wavelength of the light they produce. At such sizes--less than one hundredth the thickness of a human hair--curious aspects of quantum physics begin to take over. By exploiting this quantum behavior, researchers can tailor the basic characteristics of the devices to achieve even greater efficiencies and faster speeds.
Nanolasers could have myriad applications, for instance, in optical computers, where light would replace electricity for transporting, processing and storing information. Even though light-based computing may not occur anytime soon, other uses, such as in fiber-optic communications, have now become increasingly practical. With other researchers, I am also investigating the new lasers for novel purposes, such as the early detection of disease.
Animating Human Motion; March 1998; Scientific American Magazine; by Hodgins; 6 Page(s)
People are skilled at perceiving the subtle details of human motion. A person can, for example, often recognize friends at a distance purely from their walk. Because of this ability, people have high standards for animations that feature humans. For computer-generated motion to be realistic and compelling, the virtual actors must move with a natural-looking style.
Synthetic human motion is needed for such applications as animation, virtual environments and video games. Animators would like to be able to create a Toy Story in which the children get as much screen time as their toys. Coaches could use virtual competitors to motivate and teach aspiring athletes. Video game designers could create products with highly interactive, engaging characters. The ability to simulate human motion also has significant scientific applications in ergonomics, gait analysis of athletes and physical rehabilitation.
The Caiman Trade; March 1998; Scientific American Magazine; by Brazaitis, Watanabe, Amato; 7 Page(s)
Asmall, sleek handbag is prominently displayed in the showcase of a posh Madison Avenue store in New York City. Its $3,700 price tag tells the cognoscenti that the bag is made of real crocodilian skin, not printed calfskin. Only a handful of experts in the world may look at this handbag and know that although the glossy front is made of high-quality, legal American alligator skin, the sides are made from cheaply produced caiman leather. And the latter may have come from the largely contraband trade in skins.
Traffic-USA, a branch of the World Wildlife Fund that tracks the trade in contraband wildlife products, conservatively estimates the worldwide market for crocodilian skins at 1.5 to two million a year. Yet according to Don Ashley, a trade consultant in Tallahassee, Fla., in 1993 only about a million of those skins had legal documentation from the country of origin. So up to half of the skins that make up those expensive handbags, wallets and belts may have been harvested from wild animals, in violation of national or international laws. The bulk of these illegal skins comes from members of the genus Caiman.
Preventing the Next Oil Crunch; March 1998; Scientific American Magazine; by Staff Editor; 1 Page(s)
Enough oil remains in the earth to fill the reservoir behind Hoover Dam four times over--and that¿s just counting the fraction of buried crude that is relatively easy to recover and refine. Little wonder, then, that as the world¿s economies have hit the accelerator in the past decade, the production of oil that powers them has also soared, reaching a record of 65 million barrels a day last year. The ample supply has kept oil cheap and has helped to lay inflation low.
But could this be the peak before the fall? The authors of the first article in this special report conclude that before the next decade is over the flood of conventional oil will crest, and production will enter a permanent decline.
The End of Cheap Oil; March 1998; Scientific American Magazine; by Campbell, Laherrere; 6 Page(s)
In 1973 and 1979 a pair of sudden price increases rudely awakened the industrial world to its dependence on cheap crude oil. Prices first tripled in response to an Arab embargo and then nearly doubled again when Iran dethroned its Shah, sending the major economies sputtering into recession. Many analysts warned that these crises proved that the world would soon run out of oil. Yet they were wrong.
Their dire predictions were emotional and political reactions; even at the time, oil experts knew that they had no scientific basis. Just a few years earlier oil explorers had discovered enormous new oil provinces on the north slope of Alaska and below the North Sea off the coast of Europe. By 1973 the world had consumed, according to many experts¿ best estimates, only about one eighth of its endowment of readily accessible crude oil (so-called conventional oil). The five Middle Eastern members of the Organization of Petroleum Exporting Countries (OPEC) were able to hike prices not because oil was growing scarce but because they had managed to corner 36 percent of the market. Later, when demand sagged, and the flow of fresh Alaskan and North Sea oil weakened OPEC¿s economic stranglehold, prices collapsed.
Mining for Oil; March 1998; Scientific American Magazine; by George; 2 Page(s)
The term "oil" has, to date, been synonymous with conventional crude oil, a liquid mixture of hydrocarbons that percolates through porous strata and flows readily up drilled boreholes. But much of the world¿s remaining endowment of oil takes a less convenient form: a black, tarlike substance called bitumen, which sticks stubbornly in the pore spaces between the grains of certain sands and shales (solidified muds). Because bitumen normally will not flow through such formations, the straightforward way to recover it is to scoop it out of open-pit mines.
Digging for oil is certainly more troublesome than simply drilling and pumping, but the enormity of this resource makes it hard to ignore. Current processing methods could recover about 300 billion barrels from oil sands in the Canadian province of Alberta alone-- more than the reserves of conventional oil in Saudi Arabia. Oil shale appears to offer a less prodigious supply, but Australia contains at least 28 billion barrels of petroleum in this form, and other deposits lie buried in Estonia, Brazil, Sweden, the U.S. and China. All told, oil sands and shales around the world could, in principle, hold several trillion barrels of oil.
Oil Production in the 21st Century; March 1998; Scientific American Magazine; by Anderson; 6 Page(s)
On the face of it, the outlook for conventional oil--the cheap, easily recovered crude that has furnished more than 95 percent of all oil to date--seems grim. In 2010, according to forecasts, the world¿s oil-thirsty economies will demand about 10 billion more barrels than the industry will be able to produce. A supply shortfall that large, equal to almost half of all the oil extracted in 1997, could lead to price shocks, economic recession and even wars.
Fortunately, four major technological advances are ready to fill much of the gap by accelerating the discovery of new oil reservoirs and by dramatically increasing the fraction of oil within existing fields that can be removed economically, a ratio known as the recovery factor. These technologies could lift global oil production rates more than 20 percent by 2010 if they are deployed as planned on the largest oil fields within three to five years. Such rapid adoption may seem ambitious for an industry that traditionally has taken 10 to 20 years to put new inventions to use. But in this case, change will be spurred by formidable economic forces.
Liquid Fuels from Natural Gas; March 1998; Scientific American Magazine; by Fouda; 4 Page(s)
Recently countless California motorists have begun contributing to a remarkable transition. Few of these drivers realize that they are doing something special when they tank up their diesel vehicles at the filling station. But, in fact, they are helping to wean America from crude oil by buying a fuel made in part from natural gas.
Diesel fuel produced in this unconventional way is on sale in California because the gas from which it is derived is largely free of sulfur, nitrogen and heavy metals--substances that leave the tailpipe as noxious pollutants. Blends of ordinary diesel fuel and diesel synthesized from natural gas (currently produced commercially by Shell in Indonesia) meet the toughest emissions standards imposed by the California Air Resources Board.
The Amateur Scientist; March 1998; Scientific American Magazine; by Carlson; 3 Page(s)
If extraterrestrial scientists were ever to visit our planet, they might not pay much attention to relatively large, complex creatures like ourselves. Rather I suspect they would notice that the greatest diversity, and indeed most of the biomass, on the earth comes from its simplest residents--protozoans, fungi and algae, for example. By just about any objective measure, these organisms represent the dominant forms of life.
The world of algae is a particularly fascinating realm for amateur exploration. A single drop of pond water can harbor a breathtaking variety of microscopic species, with each algal cell constituting a complete plant. So if you want to view the essential biological underpinnings of all plant life, algae provide the best show in town.
Mathematical Recreations; March 1998; Scientific American Magazine; by Stewart; 2 Page(s)
Alan Bennett is a glassblower who lives in Bedford, England. A few years ago he became intrigued by the mysterious shapes that arise in topology--M¿bius bands, Klein bottles and the like--and came across a curious puzzle. A mathematician would have tried to solve it by doing calculations. Bennett solved it in glass. His series of remarkable objects, in effect a research project frozen in glass, is soon to become a permanent exhibit at the Science Museum in London.
Topologists study properties that remain unchanged even when a shape is stretched, twisted or otherwise distorted-- the sole proviso being that the deformation must be continuous, so that the shape is not permanently torn or cut. (It is permissible to cut the shape temporarily, provided it is eventually reconnected so that points that were originally near one another across the cut end up near one another once again.) Topological properties include connectivity: Is the shape in one piece or several? Is the shape knotted or linked? Does it have holes in it?
Reviews; March 1998; Scientific American Magazine; by Johanson; 2 Page(s)
Amomentous event transpired in human prehistory some 40,000 years ago when fully modern humans, armed with remarkably sophisticated tools and an unprecedented intelligence, began to populate Europe. Usually referred to as Cro-Magnons, these Homo sapiens encountered another species of humans, H. neanderthalensis, who had reigned unchallenged for perhaps 200,000 years throughout western Asia, most of Europe and even the British Isles. Peering out from a rock overhang, the lighter-skinned, cold-adapted Neanderthals were no doubt puzzled and frightened by the similar-looking but technologically superior beings that confronted them. These new humans brought with them a way of interacting with the world that initiated a slow but irreversible slide toward extinction for the Neanderthals.
In this superbly written book, Ian Tattersall combines his unique knowledge of the human fossil record, Paleolithic archaeology, primate behavior, prehistoric art, as well as the workings of the human brain and our extraordinary cognitive powers, to offer a convincing scenario of how we have come to hold dominion over the earth. Tattersall, who is chairman of the department of anthropology at the American Museum of Natural History in New York City, is one of our most competent and thoughtful chroniclers of human evolution, and here he ponders human uniqueness and attempts to explain the underlying processes that have made this possible. For him, "Homo sapiens is not simply an improved version of its ancestors--it¿s a new concept, qualitatively distinct from them in highly significant if limited respects." Trends in human evolution, such as increase in brain size, are discernible only in retrospect; such innovations were episodic and not the result of a process of hominization directed toward the emergence of ourselves.
Commentary : Wonders - Painters' Atoms; March 1998; Scientific American Magazine; by Morrison, Morrison; 2 Page(s)
Just west of New York City¿s Central Park, the great American Museum of Natural History prepares to move one of its finest mineral specimens. To receive this rarity, the builders are erecting a big concrete pillar, set deep into bedrock. No puny gemstone, this truck-size specimen is 15 tons of a near-stainless natural iron with a little nickel. Long, long ago that mass fell glowing out of the sky over Oregon. More than an unusual mineral, it is part of the history of asteroids and so an apt relic in its new home, the museum¿s planetarium.
Of course, iron metal itself abounds in Manhattan. Tens of millions of tons of steel, an iron-carbon alloy, form the bones of the skyline, as well as rail lines and bridge spans high and low. When melted from ore in a hot furnace, wellrefined iron seeps and flows into the bottom of its cauldron, leaving a complex, rocky slag above it. Any cosmic ball that begins as a big enough jumble of iron-bearing rocks will do much the same under self-gravity. That close analogy was grasped very early and led to the conjecture of a structure for our earth that resembles our furnace contents. The remarkable tomography extracted over the past century from careful study of earthquake tremors has fully verified the presence of iron, both fluid and solid, at the earth¿s core, the magnetized ferrosphere.
Commentary: Connections - Turkish Delight; March 1998; Scientific American Magazine; by Burke; 3 Page(s)
Iwas watching TV one chilly evening recently and thinking about sun, sand and sea when suddenly on the screen there was an ad extolling the tourist and cultural attractions of one of my favorite holiday spots: Turkey. One side of the screen showed a tulip (almost the Turkish national emblem), and the other, the ruins of ancient Troy, the city that a German eccentric called Heinrich Schliemann "found" in 1873. A self-made businessman who had made a fortune in California¿s gold fields, Schliemann had gone on to market dyestuffs in Russia. Obsessed by the writings of Homer, he decided to spend a fortune trying to prove that the Iliad, Troy and all that poetic stuff about Helen launching a thousand ships had all really happened. (He failed, but his work would later stimulate real archaeologists to take a closer look.)
An egregious, bad-tempered man, Schliemann desperately needed an aura of scientific respectability, which he acquired from his partner in these efforts: a medical genius (and fellow Homer freak) named Rudolph C. Virchow, known as the "Pope of German Medicine." Virchow virtually kicked off public health in his day and is celebrated as the discoverer of cellular pathology. It was Virchow who made the momentous statement that was to change medicine: Omnis cellula a cellula ("All cells come from other cells"). By identifying the cell as the ultimate unit of life and disease, Virchow also paved the way for chemotherapy 30 years later.
Working Knowledge; March 1998; Scientific American Magazine; by Hoffman; 1 Page(s)
Billions of electronic mail (e-mail) messages move across the Internet every year. Sending electronic letters, pictures and data files, either across a building or across the globe, has grown so popular that it has started to replace some postal mail and telephone calls. This universal medium is no longer restricted to exchange of simple text messages and is now regularly used to deliver voice mail, facsimiles and documents that may include images, sound and video.
Typically, a message becomes available to the recipient within seconds after it is sent--one reason why Internet mail has transformed the way that we are able to communicate.