15 апреля 2003 г.
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Новости науки и техники в "Scientific American"
15 апреля 2003 г. |
SAFEGUARDING GPSThe space-based Global Positioning System (GPS) signal that guides smart bombs and cruise missiles to their targets is the underpinning of U.S. technological superiority on the battlefield. Yet because it is relatively easy to jam, GPS is also the Achilles' heel of U.S. military might. Although the integrity of the GPS signal was maintained in the war with Iraq, attempts to corrupt it underscored the need to protect GPS-dependent weapons and navigation systems. Against a more capable enemy, GPS might find itself among the first casualties of any new conflict.AFRICA'S GREAT APES IN PERILThe future of our closest living relatives is much more fragile than previously thought. A new study has found that the number of great apes in the wilds of western Africa has been more than halved over the past two decades. If the current trend continues, scientists say, these primates could suffer population declines of another 80 percent over the next 30 years, endangering their survival.A TRIO OF BOOKS TRACES THE QUEST TO PROVE THE RIEMANN HYPOTHESISPRIME OBSESSION: BERNHARD RIEMANN & THE GREATEST UNSOLVED PROBLEM IN MATHEMATICS
by John DerbyshireTHE RIEMANN HYPOTHESIS: THE GREATEST UNSOLVED PROBLEM IN MATHEMATICS
by Karl SabbaghTHE MUSIC OF THE PRIMES: SEARCHING TO SOLVE THE GREATEST MYSTERY IN MATHEMATICS
by Marcus du SautoyA MAN, A PLAN, SPAMMONKEY CLONING FAILURES CAST DOUBT ON FEASIBILITY OF HUMAN REPRODUCTIVE CLONINGLike most Internet users, Stanford University law professor Lawrence Lessig hates junk e-mail - or, as it is formally known, unsolicited commercial e-mail (UCE). In fact, he hates it so much, he's put his job on the line. "I think it will work," he says of his scheme for defeating the megabyte loads of penis extenders, Viagra offers, invitations to work at home, discount inkjet cartridges, and requests for "urgent assistance" to get yet another $20 million out of Nigeria.ASTRONOMERS FIND GALAXIES DEVOID OF DARK MATTEREven though dark matter is estimated to account for up to 95 percent of the universe, it still might not be quite as all-pervasive as previously thought. An international team of astronomers has found that the mysterious material is missing from at least three elliptical galaxies.Human cloning could face obstacles greater than governmental regulations. Researchers have discovered that reproductive cloning in rhesus monkeys is hindered by the absence of key proteins that control cell division and the splitting of chromosomes. The findings indicate that reproductive cloning of primates, including humans, is unachievable using current techniques.ASK THE EXPERTS: WHY AND HOW DO PLANETS ROTATE?Physicist George Spagna of Randolph-Macon College explains.