Popular Science March 2013

WHY DO WE build incredibly tall buildings? What is it in the human psyche that requires us to go higher? Is it a masculinity problem? A desire to touch God? An unholy need to see all of the Earth at once? The early-Modernist architect Le Corbusier designed, in 1922, a “Contemporary City” for three million people. Decades before the engineering was possible, he imagined a cluster of 60-story towers that would bring a metropolis together in a single vertical habitat, leaving the surrounding countryside open. It was a revolutionary idea, but it turns out that skyscrapers beget more skyscrapers, not pristine farmland, because centralizing people into vertical habitats is a matter of economics, not land management. Now architects are redefining the notion of “tall.” Supertalls, as Clay Risen describes them…

Peter W. Singer's article on Chinese military growth [“Inside China's Secret Arsenal,” January 2013] draws a comparison to Germany out-inventing the British during World War II. Yet Singer gives no real evidence that China is likely to out-invent the U.S. That is exactly the dimension along which the Chinese system is not designed to succeed. Their low respect for intellectual property rights consistently undermines the profit motive, which is what drives meaningful leaps in R&D—whether among the Krupps of Germany or the Northrop Grummans of the U.S. Erik RichardsonMilwaukee…

Tom Foster investigated the football-helmet industry in January's “The Helmet Wars.” Online readers had their own ideas about the role of helmets in sports. Instead of a better helmet, amend the rules. In rugby, soft helmets are optional and not worn by many players. Head injuries are not a major problem. African Rover This article could apply to cycling helmets. In very oblique impacts, helmets can convert a minor injury into a brain injury. In areas that mandate helmet use for cyclists, an ethical issue arises. We should be reluctant to exchange the risk of a laceration or fractured skull for the risk of a brain injury. AveryB…

Last fall in Østerild, Denmark, the German company Siemens built the world's largest wind turbine. Each of its three rotor blades measures 246 feet—nearly the wingspan of an Airbus A380. While most turbine manufacturers make blades in two separate pieces, from molds, Siemens casts them in one piece. Because the process eliminates the need for glue, the balsa-based blades are up to 20 percent lighter than traditional ones. The reduced weight helped make it possible to build longer blades, which capture more wind and therefore generate more power. The turbine produces up to six megawatts of electricity, enough to service 6,000 households, and Siemens will install 300 in the U.K. beginning this year.…

Cellphone batteries once lasted a week on a charge. Today, power-hungry smartphones require daily plug-ins—sometimes more—which makes carrying adapters and hunting for outlets a part of everyday life. Engineers at Lilliputian Systems, a Massachusetts start-up, have developed the Nectar fuel cell, a portable charger that generates enough juice to power a USB-enabled phone once a day for two weeks. Unlike other portable power sources, which store energy in batteries, the Nectar runs on butane. When a user plugs his phone into the Nectar's USB port, a replaceable butane cartridge releases fuel into the cell. As fuel passes over a ceramic membrane, oxygen ions pass through the surface, which generates a current. The process can run as hot as 1,830°F, so the engineers built a network of insulating silicon-nitride tubes to…

Diesel-engine designers have long grappled with a dilemma: Reducing emissions meant either cutting efficiency or adding expensive equipment. With the Skyactiv-D, Mazda engineers decreased pollution, boosted mileage, and eliminated the cost of exhaust after-treatments by building the world's lowest-compression diesel engine. They then added two turbochargers and a capacitor-based regenerative braking system. When it arrives in U.S. showrooms late this year, the Skyactiv-D—equipped Mazda6 should deliver approximately 56 highway mpg while meeting strict emission standards, proving that diesel engines have many miles left in them. A two-stage turbocharging system contains a small turbine that boosts low-end torque, as well as a larger turbocharger that increases high-end horsepower. An electronic controller runs the turbochargers, tuning performance to conditions. The Skyactiv-D's engine overhaul has a side benefit: Engineers were able to build…