Scientific American Magazine
Cover; February 1995; Scientific American Magazine; by Staff Editor; 1 Page(s)
Table of Contents; February 1995; Scientific American Magazine; by Staff Editor; 2 Page(s)
Masthead; February 1995; Scientific American Magazine; by Staff Editor; 1 Page(s)
Letters To The Editors; February 1995; Scientific American Magazine; by Staff Editor; 1 Page(s)
In "The Search for Extraterrestrial Life" [SCIENTIFIC AMERICAN, October 1994], Carl Sagan makes the point that alien life would almost certainly be based on carbon because no other element "comes close to carbon in the variety and intricacy of the compounds it can form." But certain polyhedral borane molecules (near-spherical compounds of boron and hydrogen) support a chemical diversity that approaches that of organic chemistry. Assuming life has to be based on molecules with a carbon framework because of carbon's "unique" chemistry may be a bit parochial.
Sagan mentions only one of the three major SETI efforts actively looking for radio signals from extraterrestrial civilizations. For the past 22 years, Ohio State University has had a SETI program under the direction of Robert Dixon, and for the past 18 years, our group at the University of California at Berkeley has been conducting search operations on some of the world's best radio telescopes. Our project, SERENDIP, is a piggyback system that operates alongside and simultaneous with other radio astronomy observations, so our costs are very low. Unfortunately, our project is currently unfunded.
50 and 100 Years Ago; February 1995; Scientific American Magazine; by Staff Editor; 1 Page(s)
FEBRUARY 1945 Industry has begun to appreciate the service that university laboratories can provide,' Dr. Harvey A. Neville of Lehigh University said recently. 'There is an increasing realization that certain types of research can be conducted more effectively in these laboratories, where the academic atmosphere, isolated from the production process, allows a fresh perspective.
Keep an eye on lithium and its industrial applications in the near future. One fifth the weight of aluminum, this lightest of all metals is yielding to the probe of research. Today, lithium and its compounds are finding various uses in copper castings, tin bronzes and other alloys, as well as applications in the ceramic, glass and air-conditioning industries.
Dangerous Sex; February 1995; Scientific American Magazine; by Yam; 2 Page(s)
The messages have been loud and clear: anyone can get AIDS, so wear a condom, don't share needles, get tested. For more than a decade, the admonishments have helped in slowing the spread of the human immunode ficiency virus (HIV) in the U.S. Yet several recent signs point to a disturbing fact. Small pockets of the population--most notably, teenagers and young adults--appear to be ignoring the warnings about risky sexual behavior. "It could really blossom up again if we don't do something," warns Thomas J. Coates, director of the University of San Francisco Center for AIDS Prevention Studies (CAPS).
Most prevention strategies take a shotgun approach. "Some of the public information campaigns emphasize that everybody is at risk," says Don C. Des Jarlais, an AIDS researcher at Beth Israel Medical Center in New York City. "And that's probably creating some backlash." The message may have reached a saturation point with some groups. A series of CAPS studies found that in urban areas, nearly a quarter of heterosexual adults between the ages of 18 and 25 reported that they had had more than one sex partner during the past year-- a proportion that is almost three times greater than that of the general population in large cities. Forty percent of those with multiple partners never used a condom; moreover, condom usage declined with an increasing number of partners.
Putting Alzheimer's to the Tests; February 1995; Scientific American Magazine; by Beardsley; 2 Page(s)
A physician examining an elderly person suffering from mild dementia has a difficult diagnosis to make. Alzheimer's disease would be immediately suspected, but in about a third of such patients the cause is actually something different. Because brain biopsies--the only clear means of identifying the neural changes caused by the disease--are rarely performed, de- finitive diagnosis must wait until after a patient dies. Finding the true problem is crucial, however, because some conditions that mimic the symptoms of Alzheimer's, such as a brain tumor, may be readily treatable.
Last year saw an explosion of research on Alzheimer's, and several new techniques offer the hope of more certain identification. They also point to better ways of monitoring the disease's progression, which could speed the discovery of effective drugs.
Global Warming Is Still a Hot Topic; February 1995; Scientific American Magazine; by Schneider; 2 Page(s)
The question of whether the earth has succumbed to global warming has loudly been argued by scientists and politicians alike. Now the quiet voice of an electrical engineer has been added to the debate. Although the new appraisal is yet to be fully published, the analysis cries out for attention because it is novel in its approach and conclusion: not only has global warming arrived, the signal should have been obvious years ago.
The new message is reminiscent of when climate researcher James E. Hansen of the National Aeronautics and Space Administration Goddard Institute for Space Studies testified before Congress in the summer of 1988. Hansen said he was 99 percent sure that global warming was here--and few were in the mood to disagree. That summer was one of the hottest and driest in recent memory, and the temperature in Washington, D.C., was, if anything, leading the national trend in unpleasantness. So it came as no surprise that the testimony provoked a great deal of public interest and concern.
Broken Dreamtime; February 1995; Scientific American Magazine; by Stix; 2 Page(s)
The bushfires that raged in the past year or so during one of the worst dry spells in recent Australian history destroyed scores of houses. They also consumed trees that are home to animals that have helped sell airplane tickets to tourists visiting this island continent. The blazes put an additional strain on diminishing koala habitat: the land where these creatures live in eastern Australia is increasingly being sought by real-estate developers.
Koalas have come to live cheek-by-snout with people moving into coastal areas populated with the animals ' prized food. Koalas prefer to eat the leaves of less than a dozen of the 650 native varieties of eucalyptus trees. Undeniably, the past 100 years have not been good to this marsupial (koalas are bears only in their resemblance to the genus Teddy). Millions of pelts went to England around the turn of the century as a soughtafter, cheap and durable fur.
Finessing Fermat, Again; February 1995; Scientific American Magazine; by Leutwyler; 2 Page(s)
When Andrew J. Wiles of Princeton University announced in December 1993 that his proof of Fermat's Last Theorem was incomplete, some mathematicians predicted that it could take years to finish. Only 10 short months later Wiles seemingly proved them wrong and Fermat right. He has now simplified his proof of Pierre de Fermat's proposal--which the French mathematician scribbled in a book margin in the late 1630s--that the equation xn + yn = zn has no integer solutions if the exponent is greater than 2. Most experts now say the new argument looks solid.
Four scholars deemed Wiles's second proof incontestable last October. He then sent E-mail messages to some 20 colleagues, telling them a surprise package was on its way. Each received two manuscripts via express mail: Modular Elliptic Curves and Fermat's Last Theorem, offering the revised proof, and Ring Theoretic Properties of Certain Hecke Algebras, which validates an assumption used in the proof. Wiles devised the work in the latter text with a former student, Richard L. Taylor of the University of Cambridge. Both papers have been submitted to the Annals of Mathematics. "People are quite confident that this proof works," reports Henri R. Darmon of McGill University. "All the concepts involved have been studied at length, and what he's added is small."
Commanding Attention; February 1995; Scientific American Magazine; by Beardsley; 1 Page(s)
Studying consciousness is a tricky task, so researchers tease apart aspects of mental processing in the hope that the parts may yet illuminate the whole. One of those lines of inquiry recently produced attention-grabbing results--literally. At the annual meeting of the Society for Neuroscience last November, researchers presented new findings on how animals pay attention to visual cues, a process that is being studied as a surrogate for consciousness. It appears that remembered properties of objects can influence which neurons in the visual pathway show sustained activity. The outcome determines which objects¿ representations are relayed to higher brain centers.
The findings come from work in macaque monkeys. Robert Desimone and his associates at the National Institute of Mental Health studied the activity of neurons in the brains of these creatures. In one set of experiments the animals had been trained to respond to a symbol when it was flashed on a screen; an irrelevant, distracting symbol was displayed simultaneously. The scientists found that in at least two higher regions of the visual pathway, neurons that started to respond to the distracting symbol were quickly inhibited by their neighbors. When responding to the target, in contrast, neurons were not inhibited.
It's Getting Easier to Find a Date; February 1995; Scientific American Magazine; by Schneider; 2 Page(s)
In their quest to determine accurate ages for everything from superplume eruptions to hominid fossils, geologists have recently turned to the heavens. No, they are not praying for further funding. They are using astronomy to improve on their traditional geologic chronometer, the decay of radioactive elements. These researchers are forging the gears of a geologic clock from traces of the earth's orbital changes. And in the process, they are recalibrating history.
Scientists have long recognized that variations in the earth's orbit influenced ancient climates. This phenomenon occurs because shifts in the orientation of the rotation axis, in the angle of axial tilt and in the circularity of the orbit control the amount of sunlight falling at different latitudes. Such changes have, for example, ushered in and out a series of Pleistocene ice ages. These climate fluctuations are, in turn, imprinted in the sediments of the geologic record.
Seeing How the Earth Moved; February 1995; Scientific American Magazine; by Schneider; 1 Page(s)
Running interference is not confined to the football field. Scientists at the National Center for Space Studies in Toulouse, France, and at the Jet Propulsion Laboratory in Pasadena, Calif., are using the interference principle to develop new maps of earthquakes. These radar "interferograms," as they are called, can reveal the extent of deformation of the earth¿s crust that took place--even if those changes were centimeters in size. The image reproduced at the right shows, among other things, ground motion in southern California after the Landers earthquake of June 1992, which measured in at magnitude 7.3 on the Richter scale.
By juxtaposing radar images obtained by the European Space Agency¿s ERS-1 satellite before the quake with images taken several months later, researchers created interference patterns similar to those made by oil spreading on water. The color banding in the picture corresponds to the relative phase in the two superimposed radar images, which, in turn, depends on the height of the local topography and on changes in topography caused by the quake.
Nothing Personal, You're Just Not My Type; February 1995; Scientific American Magazine; by Mirsky; 2 Page(s)
The world was safe all along. Back in the 1950s, moviemakers regularly served up the spectacle of creatures from other planets attempting to take over our bucolic little orb. Heroic earthlings fought the aliens with dynamite, napalm, atomic torpedoes and bad acting. But had the heroes been better acquainted with life-history strategies--the reproductive behaviors that determine patterns of population growth--they might not have bothered.
In general, says May R. Berenbaum, professor of entomology at the University of Illinois, "none of [the aliens] exhibit the opportunistic sorts of reproductive traits or characteristics of organisms that successfully colonize." Her findings help to explain why earthlings should be afraid of at least some contemporary invaders--such As zebra mussels, bark beetles, medflies and, perhaps, the sluglike aliens featured in one of last year's movies, the Puppet Masters.
Out of the Lab and into the Fire; February 1995; Scientific American Magazine; by Nemecek; 2 Page(s)
Downstairs from the First Ladies' inaugural gowns and not too far from the television-set chairs of Edith and Archie Bunker in the National Museum of American History in Washington, D. C., sprawls the show "Science in American Life." The exhibit, which opened last April, as well as an upcoming one, "The Last Act: The Atomic Bomb and the End of World War II," which debuts in May at the National Air and Space Museum, has provoked heated debate about the way science and technology are portrayed. Behind this contentious argument lies a larger issue: whether scientists are no longer perceived by the public as revered truthseekers but as flawed humans whose theories and technology simply reflect contemporary cultural concerns.
Some observers claim that the exhibits sacrifice scientific and historical accuracy to concentrate on social issues. The current show, for instance, looks at the environmental movement and discrimination against women and minorities within the scientific community. Two life-size talking mannequins re-create researchers arguing over who deserves credit for discovering saccharine. And the area devoted to the present day depicts both "spectacular advances in space exploration, electronics and medicine" and disasters such as Three Mile Island and the explosion of the space shuttle Challenger. Such events have, according to the exhibit's literature, encouraged people to question all authority, scientific or otherwise.
No, Really, It Was This Big; February 1995; Scientific American Magazine; by Vames; 1 Page(s)
Researchers at Fisheries and Oceans Canada in West Vancouver have engineered a fly-fisherman¿s fantasy. Robert H. Devlin and his colleagues altered the DNA of Pacific salmon to create fish that are, on average, more than 11 times bigger than their natural counterparts.
To spawn these gargantuan creatures, the group used the process that has stimulated similar growth in transgenic mice. The investigators microinjected growth promoter genes from two sources into the Pacific salmon eggs. The first source was a nonhomologous species--in this case, the mouse. The second, homologous source was sockeye salmon. The scientists then hatched the some 3,000 eggs and examined the offspring that survived to at least one year of age.
The Analytical Economist; February 1995; Scientific American Magazine; by McCloskey; 1 Page(s)
Determining what drives economic growth or decline depends as much on storytelling as on data. For the past decade or so, a new crop of theorists, including Paul Romer of the University of California at Berkeley and Robert Lucas of the University of Chicago, has been pushing "endogenous" growth. These economists argue that development results entirely from economic factors: once upon a time the U. S. was poor; then its population grew and became urbanized, allowing business to exploit economies of scale. As a result, the country became rich. There are even mathematical models to prove it. Economists understand all the variables in this story-- population, production costs and profits--and so it is called endogenous (inside the economics).
Economic historians such as Joel Mokyr of Northwestern University and Nathan Rosenberg of Stanford University, meanwhile, favor "exogenous" explanations based on outside factors, in particular technological change. Once upon a time we were all poor; then a wave of gadgets swept over England. As a result, we are all rich, or well on our way to it, if we will let people alone. This story does a better job of explaining, for instance, why China's per capita income grows by 10 percent a year: the Chinese, like the Koreans and Japanese before them, adopt the best methods invented thus far and quickly catch up with more advanced nations, regardless of endogenous factors in their economy.
A Budgetary Storm Is Brewing; February 1995; Scientific American Magazine; by Beardsley; 1 Page(s)
Prospects for federal research and development are up in the air as Republicans looking for budget cuts take control on Capitol Hill. Although it is too early to say where the chips will fall, clear signs indicate that science and technology will not be spared in the housecleaning.
Before last November's elections, Republican staff of the House Budget Committee startled science watchers by publishing a series of draconian possible cuts. The list included abolishing the U. S. Geological Survey and the National Biological Survey as well as limiting the annual growth of the National Science Foundation to 1 percent less than the rate of inflation, which is now 2.7 percent. The Advanced Technology Program of the National Institute of Standards and Technology-- which in recent years has become the centerpiece of the administration 's technology development efforts--was also targeted.
Agents and Other Animals; February 1995; Scientific American Magazine; by Browning; 2 Page(s)
Great things are expected of agents, little pieces of software designed to roam around computer networks making themselves useful. Agents "give people the magical ability to project their desires into cyberspace, " raves Marc Porat, who, together with veterans of the team that designed the Apple Macintosh, founded a company called General Magic in Mountain View, Calif., to put agent technology on the market. Meanwhile Microsoft, Apple and others are touting "wizards" and "intelligent agents" that, their advertisements promise, will make complex tasks a snap.
People should know better. Agents are rapidly catching a bad case of the worst kind of computer industry hype: misplaced expectations. It's not that agents won't deliver great things; they probably will. But those great things will almost certainly be different from the ones consumers now expect. Marketers promise Jeeves the perfect butler, but researchers are quite literally struggling to build Bonzo the wonder dog--"and, frankly, even a dog looks pretty ambitious," says Pattie Maes, a researcher at the Media Lab of the Massachusetts Institute of Technology.
How Do They Call It? Let Us Count the Ways; February 1995; Scientific American Magazine; by Staff Editor; 1 Page(s)
Since the phrase first appeared in 1992, the "information superhighway" has become a familiar part of the American lexicon. Its synonyms, according to a report by the Freedom Forum Media Studies Center at Columbia University, remain somewhat less popular in the newspapers, magazines and broadcasts that were reviewed (left). At the same time, however, the concept seems to have peaked before its prime, well before the highway is laid down.
The Chilling Wind of Copyright Law?; February 1995; Scientific American Magazine; by Wallich; 1 Page(s)
If one of the committees trying to define the future of the Internet is right, pretty much everything anyone does in cyberspace may be illegal. The Working Group on Intellectual Property Rights of the White House Information Infrastructure Task Force is not even talking about hacking or software piracy or thefts of confidential information. The team is crafting a whole new definition of copyright law.
According to the group's draft report--issued last summer and the subject of recent public hearings--random browsing of World Wide Web pages, transmission of Usenet postings, reading of electronic mail or any of the other Internet activities may already violate the law. "It's really that bad," says Jessica Litman, a professor of copyright law at Wayne State University. She explains that the team's chairman, Bruce A. Lehman of the Department of Commerce, has made a peculiar reading of a part of the copyright act that applies to computer software and has extended it to all digital data.
Profile: Yoichiro Nambu; February 1995; Scientific American Magazine; by Mukerjee; 3 Page(s)
Ifirst saw Yoichiro Nambu almost 10 years ago, from the back row of a graduate seminar in physics at the University of Chicago. A small man in a neat suit, he was sketching long, snaking tubes on the blackboard. Sometimes he said they were vortex lines, found in superconductors; other times he called them strings, connecting quarks. Mystified, and yet fascinated by a bridge between such disparate realms, I later asked him to be my thesis adviser.
Face to face, Nambu was still hard to understand. I was clearly not the first to try. Bruno Zumino of the University of California at Berkeley once recounted his own attempts: "I had the idea that if I can find out what Nambu is thinking about now, I'll be 10 years ahead in the game. So I talked to him for a long time. But by the time I fi- gured out what he said, 10 years had passed." Edward Witten of the Institute for Advanced Study in Princeton, N. J., explains: "People don't understand him, because he is so farsighted."
Population, Poverty and the Local Environment; February 1995; Scientific American Magazine; by Dasgupta; 6 Page(s)
As with politics, we all have widely differing opinions about population. Some would point to population growth as the cause of poverty and environmental degradation. Others would permute the elements of this causal chain, arguing, for example, that poverty is the cause rather than the consequence of increasing numbers. Yet even when studying the semiarid regions of sub-Saharan Africa and the Indian subcontinent, economists have typically not regarded poverty, population growth and the local environment as interconnected. Inquiry into each factor has in large measure gone along its own narrow route, with discussion of their interactions dominated by popular writings--which, although often illuminating, are in the main descriptive and not analytical.
Over the past several years, though, a few investigators have studied the relations between these ingredients more closely. Our approach fuses theoretical modeling with empirical findings drawn from a number of disciplines, such as anthropology, demography, ecology, economics, nutrition and political science. Focusing on the vast numbers of small, rural communities in the poorest regions of the world, the work has identi fied circumstances in which population growth, poverty and degradation of local resources often fuel one another. The collected research has shown that none of the three elements directly causes the other two; rather each influences, and is in turn influenced by, the others. This new perspective has significant implications for policies aimed at improving life for some of the world's most impoverished inhabitants.
Sonoluminescence: Sound into Light; February 1995; Scientific American Magazine; by Putterman; 6 Page(s)
Imagine you are riding a roller coaster. First, you chug up a long incline slowly. When you get to the top, your car free-falls, speeding up until it reaches the bottom of the drop, where the deceleration crams you into your seat. That sensation is what you would feel if you were riding a pulsating bubble of air trapped in water--except that the drop would reach supersonic speeds and at the bottom you would be crushed into your seat with a force equal to 1,000 billion times your weight.
Obviously, more than your stomach would react to such a ride. As for the bubble, it responds to the extraordinary force by creating a flash of light only a tiny fraction of a second long. The light is mostly ultraviolet, which indicates that when the bubble's free fall stops, its interior becomes much hotter than the surface of the sun. A sound wave can make the bubble repeat this wild ride more than 30,000 times a second, so that the flashes burst out with clocklike regularity.
Molecular Machines That Control Genes; February 1995; Scientific American Magazine; by Tjian; 8 Page(s)
Asthma, cancer, heart disease, immune disorders and viral infections are seemingly disparate conditions. Yet they turn out to share a surprising feature. All arise to a great extent from overproduction or underproduction of one or more proteins, the molecules that carry out most reactions in the body. This realization has recently lent new urgency to research aimed at understanding, and ultimately manipulating, the fascinating biochemical machinery that regulates an essential step in protein synthesis: the transcription of genes. For a protein to be generated, the gene that specifies its composition must be transcribed, or copied, from DNA into strands of messenger RNA, which later serve as the templates from which the protein is manufactured.
Even before therapy became a goal, transcription had long captivated scientists for another reason: knowledge of how this process is regulated promises to clarify some central mysteries of life. Each cell in the body contains the same genome, the complement of some 150,000 genes that form the blueprint for a human being. How is it that the original cell of an organism-- the fertilized egg--gives rise to a myriad of cell types, each using somewhat different subsets of those genes to produce different mixtures of proteins? And how do the cells of a fully formed body maintain themselves, increasing and decreasing the amounts of proteins they manufacture in response to their own needs and those of the larger organism?
Manic-Depressive Illness; February 1995; Scientific American Magazine; by Jamison; 6 Page(s)
Men have called me mad," wrote Edgar Allan Poe, "but the question is not yet settled, whether madness is or is not the loftiest intelligence--whether much that is glorious-- whether all that is profound--does not spring from disease of thought--from moods of mind exalted at the expense of the general intellect."
Many people have long shared Poe's suspicion that genius and insanity are entwined. Indeed, history holds countless examples of "that fine madness." Scores of influential 18th- and 19th-century poets, notably William Blake, Lord Byron and Alfred, Lord Tennyson, wrote about the extreme mood swings they endured. Modern American poets John Berryman, Randall Jarrell, Robert Lowell, Sylvia Plath, Theodore Roethke, Delmore Schwartz and Anne Sexton were all hospitalized for either mania or depression during their lives. And many painters and composers, among them Vincent van Gogh, Georgia O'Keeffe, Charles Mingus and Robert Schumann, have been similarly afflicted.
Masers in The Sky; February 1995; Scientific American Magazine; by Elitzur; 7 Page(s)
Three decades ago radio astronomers began to detect signals unlike any they had ever expected to see. In 1963 a team led by Alan H. Barrett of the Massachusetts Institute of Technology discovered radio signals from clouds of excited molecules in interstellar space. Many astrophysicists had believed molecular clouds could not form in the regions between stars, but the group's findings were anomalous for another reason as well. The first molecule they detected, the hydroxyl radical (OH), emitted radiation whose patterns appeared to contradict the rules of statistical physics. Emission lines that should have been strong were weak, and ones that should have been weak were intense.
In 1965 a team led by Harold F. Weaver of the University of California at Berkeley detected radiation whose properties were so unusual that they dubbed the emitting substance "mysterium," for lack of an obvious explanation. The microwaves they found were extraordinarily bright, every emission line covered a tiny range of wavelengths (as opposed to the broader peaks that researchers had seen in other sources), and the radiation was almost all polarized in the same sense, even though light and radio waves emitted by astronomical sources generally consist of photons each randomly polarized in a different sense.
The History of Synthetic Testosterone; February 1995; Scientific American Magazine; by Hoberman, Yesalis; 6 Page(s)
On June 1, 1889, Charles .douard Brown-S.quard, a prominent French physiologist, announced at the Soci.t. de Biologie in Paris that he had devised a rejuvenating therapy for the body and mind. The 72-year-old professor reported that he had drastically reversed his own decline by injecting himself with a liquid extract derived from the testicles of dogs and guinea pigs. These injections, he told his audience, had increased his physical strength and intellectual energy, relieved his constipation and even lengthened the arc of his urine.
Almost all experts, including some of Brown-S.quard's contemporaries, have agreed that these positive effects were induced by the power of suggestion, despite Brown-S.quard's claims to the contrary. Yet he was correct in proposing that the functions of the testicles might be enhanced or restored by replacing the substances they produce. His achievement was thus to make the idea of the "internal secretion," initially proposed by another well-known French physiologist, Claude Bernard, in 1855, the basis of an organotherapeutic "replacement " technique. Brown-S.quard's insight that internal secretions could act as physiological regulators (named hormones in 1905) makes him one of the founders of modern endocrinology. So began an era of increasingly sophisticated hormonal treatments that led to the synthesis in 1935 of testosterone, the primary male hormone produced by the testicles.
The Mid-Cretaceous Superplume Episode; February 1995; Scientific American Magazine; by Larson; 5 Page(s)
At one o'clock in the morning on December 13, 1989, I was awakened in my bunk on board the scientific drillship JOIDES Resolution by the sounds of celebration in the adjoining cabin. Since I had to relieve the watch at four anyway, I stumbled next door to join the party. The paleontologists in our expedition had just reported to my co¿chief scientist, Yves Lancelot, now at the University of Aix-Marseilles, that microfossils of the Jurassic period had been recovered from the hole in the floor of the western Pacific Ocean that we were drilling more than three miles below us. Two days later the drill reached the volcanic basement-- oceanic crust of Middle Jurassic age, about 165 million years old. A 20-year mystery was solved. At last, we had hard evidence of the world's oldest deep-sea sediments and volcanic rocks that are still in place from eons ago.
In succeeding days I reflected on why the quest had taken so long. My colleagues Clement G. Chase of the University of Arizona, Walter C. Pitman III of Lamont-Doherty Geological (Earth) Observatory, Thomas W. C. Hilde of Texas A&M University and I had first considered the problem in the 1970s. The target was not a small one. We had predicted from geophysical data that an area in the western Pacific the size of the continental U. S. should be Jurassic in age, somewhere between 145 and 200 million years old. But whenever we dredged or drilled in this area, we almost invariably recovered rocks called basalts, formed by volcanic eruptions during the mid-Cretaceous, generally ranging in age from 80 to 120 million years and no older. The first such basalt samples were dredged from the Mid-Pacific Mountains in 1950 by an early expedition of the Scripps Institution of Oceanography. Until the JOIDES discovery, however, geologists had not made much progress in answering the questions concerning the origin of the seemingly ever present mid-Cretaceous basalts or the possible existence of underlying Jurassic material.
Toward "Point One"; February 1995; Scientific American Magazine; by Stix; 6 Page(s)
At a technical conference this month, engineers will present papers describing a memory chip that can hold a billion bits of information and a microprocessor that performs in excess of a billion instructions per second, a 1,000-fold increase in capacity and processing power since the early 1980s. Organizers of the IEEE International Solid-State Circuits Conference expect the relentless progression of semiconductor technology to continue: they contend that papers on terachips (capable of handling a trillion bits or instructions) will arrive by the end of the next decade.
The optimism of the research establishment conceals the growing difficulties of converting laboratory samples into real manufacturing items. A pocket videophone or high-resolution teleconferencing system will depend on continuing advances in the greatest massproduction technique of all time. "An electronic memory circuit will have gone from $10 in the 1950s down to a hundred thousandth of a cent a few years from now," says Alec N. Broers, head of the engineering department at the University of Cambridge. "It's gone further than any technology in history."
The Amateur Scientist; February 1995; Scientific American Magazine; by Hiller, Barber; 3 Page(s)
Aglowing bubble of air cannot be bought anywhere at any price. But with an oscilloscope, a moderately precise sound generator, a home stereo amplifier and about $100, readers can turn sound into light through a process called sonoluminescence [see "Sonoluminescence: Sound into Light," by Seth J. Putterman; page 70]. The apparatus is relatively simple. A glass spherical flask filled with water serves as the resonator--the cavity in which sound is created to trap and drive the bubble. Small speakers, called piezoelectric transducers, are cemented to the flask and powered by an audio generator and amplifier. Bubbles introduced into the water coalesce at the center of the flask and produce a dim light visible to the unaided eye in a darkened room.
The filled flask must be vibrated at its resonant frequency--that is, at the sound frequency at which it responds most intensely. The resonant frequency equals the speed of sound in water (1,500 meters per second) divided by the diameter of the sphere. The glass will cause the actual resonance frequency to be about 10 percent higher. We used a 100-milliliter Pyrex spherical boiling flask with a diameter of 6.5 centimeters. Filled with water, the container resonated at about 25 kilohertz. A smallnecked flask will produce the best results. Grease and oil can interfere with the bubble, so the glassware should be thoroughly washed with soap and water and rinsed well.
Book Review; February 1995; Scientific American Magazine; by Kamin; 5 Page(s)
This book, with 400,000 copies in print just two months after its publication, has created an enormous stir. The authors unabashedly assert that scientific evidence demonstrates the existence of genetically based differences in intelligence among social classes and races. They maintain further that data from some 1,000 publications in the social and biological sciences show that attributes such as employment, income, welfare dependency, divorce and quality of parental behavior are determined by an individual's intelligence. These claims--another eruption of the crude biological determinism that permeates the history of IQ testing-- lead Herrnstein and Murray to a number of social policy recommendations. The policies would not be necessary, or humane, even if the cited evidence were valid. But the caliber of the data in The Bell Curve is, at many critical points, pathetic. Further, the authors repeatedly fail to distinguish between correlation and causation and thus draw many inappropriate conclusions.
I will deal first with an especially troubling example of the quality of the data on which Herrnstein and Murray rely. They ask, "How do African-Americans compare with blacks in Africa on cognitive tests?" They reason that low African- American IQ scores might be the result either of a history of slavery and discrimination or of genetic factors. Herrnstein and Murray evidently assume that blacks reared in colonial Africa have not been subjected to discrimination. In their view, if low IQ scores of African-Americans are a product of discrimination, rather than genes, black Africans should have higher Iqs than African-Americans.
Essay; February 1995; Scientific American Magazine; by Eisenberg; 1 Page(s)
The age of CD-ROMs is upon us. Scientists have their reservations about the silvery discs--"I know a few four-year-olds who like them; I myself prefer books," one math professor told me. But they are starting to buy these digital media anyway, the better to pursue their research, their businesses and even the occasional browse through The Haldeman Diaries or the NASA Viking photographs of the surface of Mars.
That CD-ROMs and technically minded people would eventually find one another was destiny, given the attractive combination of the practical and the pleasurable the discs offer. Still, the union had a slow beginning. Compactdisc technology was originally developed for audio recordings. By the mid-1980s it had been adapted as a dense storage medium for other types of data: a single disc holds hundreds of times the data of a floppy diskette. (Unlike floppies, however, these discs have read-only memory, meaning that once the data are recorded, they cannot be changed.) By the start of 1994 roughly 8,000 CD-ROM titles were available--very few of them appealing to scientists.