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The U.S. officially committed in writing yesterday to the greenhouse gas emission cuts proposed by President Obama in Copenhagen—4 percent below 1990 levels by 2020. The letter to the United Nations Framework Convention on Climate Change (UNFCCC) commits the nation to combat climate change, but with a caveat: any such commitment must be backed by legislation, which has not passed the U.S. Senate. “The U.S. submission reflects President Obama’s continued commitment to meeting the climate change and clean energy challenge through robust domestic and international action that will strengthen our economy, enhance our national security, and protect our environment,” said U....

The chunks of ice and dust that make their home in the Oort cloud, far beyond the orbit of Pluto, sometimes become dislodged and head into the solar system as streaky comets. Some disruptions, caused by passing stars and other interactions with the Milky Way galaxy, are severe enough to send Oort comets into orbits that buzz or even collide with Earth. New simulations have revealed a novel mechanism for their entry into our part of the solar system, a method that also suggests that comet showers may not have been strongly involved in major extinctions on Earth....

NASHVILLE, Tenn.—The conservative movement might have given U.S. EPA Administrator Scott Pruitt cover for one of the few climate change fights he’s hesitated to embrace. Pruitt has expressed cautiousness about challenging the endangerment finding, the tome of scientific evidence for the harmful impacts of greenhouse gas emissions on human health. He’s said “it needs to be enforced and respected,” and those familiar with Pruitt’s thinking say he believes challenging the finding is an uphill battle, costly and unlikely to succeed....

A recent tabloid captured the common wisdom about anorexia nervosa. In an interview, actor Christina Ricci blamed the pressures of success for her prior struggle with the disease. The headline flashed, “Ricci: Hollywood made me anorexic.” But did it? True, anorexia is characterized by compulsive dieting or exercise to get thin. And the pursuit of thinness in contemporary culture—particularly in Hollywood—has become a seemingly contagious obsession. Yet there is thin, and then there is emaciated....

The long search for an AIDS vaccine has produced countless false starts and repeated failed trials, casting once bright hopes into shadows of disenchantment. The now familiar swings appeared in high relief last fall, with news of the most recent, phase III trial in Thailand. Initial fanfare for a protective outcome gave way to disappointment after reanalysis showed that the protection could be attributed only to chance. But rather than dashing all hopes for an AIDS vaccine, the trial has heartened some researchers, who see new clues in the battle against the fatal illness....

April 1967 Race Relations “The concept of ‘black power’ is an inflammatory one. It was introduced in an atmosphere of militancy (during James Meredith’s march through Mississippi last June) and in many quarters it has been equated with violence and riots. The fact is that a form of black power may be absolutely essential. The experience of Negro Americans, supported by numerous historical and psychological studies, suggests that the profound needs of the poorest and most alienated Negroes cannot be met—and that there can therefore be no end to racial unrest—except through the influence of a unified, organized Negro community with genuine political and economic power....

WASHINGTON, D.C.—One of the most difficult tasks to teach Air Force pilots who guide unmanned attack drones is how to pick out targets in complex radar images. Pilot training is currently one of the biggest bottlenecks in deploying these new, deadly weapons. So Air Force researchers were delighted recently to learn that they could cut training time in half by delivering a mild electrical current (two milliamperes of direct current for 30 minutes) to pilot’s brains during training sessions on video simulators....

A foreign beetle imported to attack invasive trees in the U.S. Southwest may have brought its own culinary agenda. Researchers in Utah and Arizona are sounding the alarm about salt cedar leaf beetles, which were imported from Kazakhstan several years ago to control invasive tamarisk trees. “Now that the beetle is spreading to large areas, we need to start looking for unexpected consequences of defoliation and death of the tamarisk,” says Philip Dennison, a geographer at The University of Utah and lead author of a study warning of the unintended risks published this month in the online edition of the journal Remote Sensing of Environment....

To many people, black holes evoke a mysterious darkness threatening to swallow you up. To scientists, they have sometimes seemed like the mystery that might swallow physics. They awkwardly bridge the theories of quantum mechanics and general relativity, exposing deep weaknesses in our understanding of nature. But recent theoretical and observational advances have helped illuminate these shadowy objects, with profound implications for more than just black holes themselves. George Musser describes how physicists have made breakthroughs toward resolving a decades-old quandary called the black hole information paradox....

When basketball legend Magic Johnson announced in 1991 that he had tested positive for HIV, it was a death sentence, and he promptly retired from the Los Angeles Lakers. Fans mourned his coming demise, but to everyone’s astonishment, Magic’s life continued in relative normalcy. A quarter of a century later he is an active entrepreneur, business leader, philanthropist and advocate for HIV/AIDS prevention. Magic’s story is emblematic of one of the great medical achievements of our time....

A geologic scar left by a catastrophic Texas flood in 2002 is providing an unexpected scientific benefit. A new study demonstrates how researchers can use a channel carved by floodwaters pouring over the dam of a flooded reservoir as a laboratory to test scientific theories of how such canyons are formed. The research could help to inform the hydrological histories of Earth and Mars by indicating the kind of imprints large, sudden floods leave on a planet’s surface....

In the final years of his nearly 30-year career in the U.S. Air Force, Slim spent 10 to 12 hours a day in a cool, dark room in the Arizona desert, stationed in front of monitors that beamed back aerial footage from Afghanistan. Slim’s unit operated around the clock, flying Predator drones thousands of miles away over Afghanistan, to monitor — and sometimes eliminate — “targets” across the war-ridden country. As a sensor operator for these remotely piloted aircraft, or RPAs, it was his job to coordinate the drones’ onboard cameras, and, if a missile was released, to laser-guide the weapon to its destination....

Anatomical features that took millennia to evolve can revert in a single generation. Specifically, sex between blind cavefish, if done right, can lead to progeny that can see. The blind, albino, cave-dwelling form of the Mexican tetra (Astyanax mexicanus) evolved from ancestors living near the water’s surface whose eyesight withered after they descended into complete darkness roughly one million years ago. These cavefish, which thrive in the freshwater caves of northeastern Mexico, can reach about 12 centimeters in length, and skin grows over their useless eyes....

A group of astrophysicists has located two massive bubbles of plasma, each extending tens of thousands of light-years, emitting high-energy radiation above and below the plane of the galaxy. The researchers found the structures in publicly released data from NASA’s Fermi Gamma-Ray Space Telescope, which was launched in 2008 to investigate sources of extremely energetic photons—namely, gamma rays, which have higher frequencies than x-rays. From its orbital perch hundreds of kilometers above Earth’s surface, Fermi has charted the location of gamma-ray sources with its Large Area Telescope (LAT)....

Mickey Parish, chair of the Nutrition and Food Science Department at the University of Maryland, explains. Protection of foods from microbial spoilage using salt (usually sodium chloride) or sugar (usually sucrose) has ancient roots and is often referred to as salting, salt curing, corning or sugar curing. (Pieces of rock salt used for curing are sometimes called corns, hence the name “corned beef.”) Curing may utilize solid forms of salt and sugar or solutions in which salt or sugar is mixed with water....

Like athletes or musicians, people who practice meditation can enhance their ability to concentrate—or even lower their blood pressure. They can also cultivate compassion, according to a new study. Specifically, concentrating on the loving kindness one feels toward one’s family (and expanding that to include strangers) physically affects brain regions that play a role in empathy. “There is such a thing as expertise when it comes to complex emotions or emotional skills, such as the one of cultivating benevolence,” says Antoine Lutz, a neuroscientist at the University of Wisconsin–Madison who led the study....

Hospitals and airplanes ban the use of cell phones, because their electromagnetic transmissions can interfere with sensitive electrical devices. Could the brain also fall into that category? Of course, all our thoughts, sensations and actions arise from bioelectricity generated by neurons and transmitted through complex neural circuits inside our skull. Electrical signals between neurons generate electric fields that radiate out of brain tissue as electrical waves that can be picked up by electrodes touching a person’s scalp....

Before compact fluorescent light bulbs and ethanol, the first line of defense against global warming was planting trees. Forests, after all, cool the atmosphere by drinking in carbon dioxide from the air. A new study, however, published in Proceedings of the National Academy of Sciences reports that forests’ other climatic effects can cancel out their carbon cleaning advantage in some parts of the world. Using a three-dimensional climate model, the research team mimicked full global deforestation and also studied the effects of clear-cutting in different regions of latitude, such as the tropics and boreal zones....

To many of us, Alzheimer’s disease is a familiar and terrifying malady. Afflicting an estimated 5.3 million people in the U.S. alone, the disorder slowly and relentlessly robs patients of memory, judgment and perception—eventually corroding even their ability to perform everyday tasks. The mechanisms that underlie these symptoms are not yet fully understood. The disease is largely attributed to an abnormal buildup of proteins, which can form amyloid beta plaques and tangles in the brain that trigger inflammation and result in the loss of brain connections called synapses, the effect most strongly associated with cognitive decline....

Quantum computing has long seemed like one of those technologies that are 20 years away, and always will be. But 2017 could be the year that the field sheds its research-only image. Computing giants Google and Microsoft recently hired a host of leading lights, and have set challenging goals for this year. Their ambition reflects a broader transition taking place at start-ups and academic research labs alike: to move from pure science towards engineering....