Scientific American - Scientific American Magazine

Swept from Africa to the Amazon (preview)

Wed, 01 Feb 2012 00:00:00 EST

The Bodele depression at the southern edge of the Sahara is a fearsome, forsaken place. Winds howl through the nearby Tebesti Mountains and Ennedi Plateau, picking up speed as they funnel into a parched wasteland nearly the size of California. Once there was a massive freshwater lake here. Now the lake is a shrunken puddle of its former self. Across most of the landscape, there is nothing.

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Illusion Contest Offers Mind-Warping Visions (preview)

Sun, 01 Jan 2012 00:00:00 EST

Jordan Suchow came to three rapid-fire conclusions as he watched his Macintosh laptop plummet toward the floor. First, in approximately 300 milliseconds he was going to be in a heap of trouble--the machine had been given to him by his thesis adviser, George Alvarez of Harvard University. Second, hoping against all hope, he decided that Harvard could probably afford to buy him a new computer. Third, he realized that the most important observation of his life was unfolding right in front of him as his laptop accelerated toward the parquet: the onscreen doughnut that he had programmed to scintillate appeared to have stopped doing so.

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Controversy: Can Repeat Concussions Cause Lou Gehrig's Disease? (preview)

Wed, 01 Feb 2012 00:00:00 EST

Kevin Turner was a premier athlete in the National Football League, a fullback who could run, catch and block. At 6' 1" and roughly 230 pounds, he was slightly undersized for his position, but he had tremendous thrust in his legs and used all of it to launch himself into players who were bigger than he was. He played for the New England Patriots from 1992 to 1994, then joined the Philadelphia Eagles, with whom he stayed until his abrupt retirement in 1999. Some called him “the Collision Expert”--a nickname he got because of the gouges he collected on his helmet.

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Fetal Armor: How the Placenta Shapes Brain Development (preview)

Wed, 01 Feb 2012 00:00:00 EST

The placenta is unique among organs--critical to human life yet fleeting. In its short time of duty, it serves as a vital protective barrier to the fetus. The organ’s blood vessels--which resemble tree roots in this image by Norman Barker, associate professor of pathology at the Johns Hopkins University School of Medicine--also deliver essential oxygen and nutrients from the mother to her developing baby. Still, the placenta has been vastly underappreciated. Scientists are taking a closer look and finding that it is much more than a simple conduit: it actively protects the fetus and shapes neurological development.

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Designers of Exotic Materials Learn New Tricks from Animals (preview)

Wed, 01 Feb 2012 00:00:00 EST

Among the first things you notice when you step into the corner office of Harvard University professor Joanna Aizenberg are the playthings. Behind her desk sit a sand dollar, an azure butterfly mounted in a box, a plastic stand with long fibers that erupt in color when a switch is pulled, and haphazard rows of toys. Especially numerous are the Rubik’s cubes--the classic three-by-three, of course, but also ones with four, five, six and even seven mini cubes along each edge. An eight-year-old would be in heaven.

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Scientists Manipulate and Erase Memories (preview)

Sun, 01 Jan 2012 00:00:00 EST

Joël Coutu knelt on the cold cement floor of the pet supply store he managed in Montreal, his wrists bound behind him with telephone wire. He could feel the barrel of a pistol pressed against the back of his neck. “You’re lying!” the gunman screamed. “And I am going to blow your head off.”

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How Scientists Are Tackling the Bed Bug Nightmare (preview)

Wed, 01 Feb 2012 00:00:00 EST

The elderly man lived by himself in a low-income apartment near Cincinnati. But he was not alone. After dark the bed bugs would emerge from his recliner and tattered box-spring mattress to feed on his blood. Judging from the thousands of insects I found in his home, I would venture that it had been this way for many months. Imprisoned by poverty and infirmity, the man had nourished generations of these pests, enduring their bites night after night while their numbers swelled.

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Forgetting Actually Strengthens Memory--a Special Report (preview)

Sun, 01 Jan 2012 00:00:00 EST

Most people picture human memory as something resembling a secure metal vault into which we cram our valuable--and not so valuable--thoughts for safekeeping. The people with the biggest vaults, then, can keep the most stuff. They know the most and make the fewest mistakes. [More]

Is Space Digital? (preview)

Wed, 01 Feb 2012 00:00:00 EST

Craig Hogan believes that the world is fuzzy. This is not a metaphor. Hogan, a physicist at the University of Chicago and director of the Fermilab Particle Astrophysics Center near Batavia, Ill., thinks that if we were to peer down at the tiniest subdivisions of space and time, we would find a universe filled with an intrinsic jitter, the busy hum of static. This hum comes not from particles bouncing in and out of being or other kinds of quantum froth that physicists have argued about in the past. Rather Hogan’s noise would come about if space was not, as we have long assumed, smooth and continuous, a glassy backdrop to the dance of fields and particles. Hogan’s noise arises if space is made of chunks. Blocks. Bits. Hogan’s noise would imply that the universe is digital.

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The Science of the Glory (preview)

Sun, 01 Jan 2012 00:00:00 EST

On a daytime flight pick a window seat that will allow you to locate the shadow of the airplane on the clouds; this requires figuring out the direction of travel relative to the position of the sun. If you are lucky, you may be rewarded with one of the most beautiful of all meteorological sights: a multicolored-light halo surrounding the shadow. Its iridescent rings are not those of a rainbow but of a different and more subtle effect called a glory. It is most striking when the clouds are closest because then it dominates the whole horizon.

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Are Physical Constants Really Constant?

Sun, 01 Jan 2012 00:00:00 EST

Some things never change. physicists call them the constants of nature. Such quantities as the velocity of light, c , Newton’s constant of gravitation, G , and the mass of the electron, m e , are assumed to be the same at all places and times in the universe. They form the scaffolding around which the theories of physics are erected, and they define the fabric of our universe. Physics has progressed by making ever more accurate measurements of their values.

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A Brief History of Clocks

Sun, 01 Jan 2012 00:00:00 EST

Humankind’s efforts to tell time have helped drive the evolution of our technology and science throughout history. The need to gauge the divisions of the day and night led the ancient Egyptians, Greeks and Romans to create sundials, water clocks and other early chronometric tools. Western Europeans adopted these technologies, but by the 13th century, demand for a dependable timekeeping instrument led medieval artisans to invent the mechanical clock. Although this new device satisfied the requirements of monastic and urban communities, it was too inaccurate and unreliable for scientific application until the pendulum was employed to govern its operation. The precision timekeepers that were subsequently developed resolved the critical problem of finding a ship’s position at sea and went on to play key roles in the industrial revolution and the advance of Western civilization.

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Middleweight Black Holes: Clues to the Universe's Evolution (preview)

Sun, 01 Jan 2012 00:00:00 EST

Astronomers have known for some 10 years that nearly every large galaxy contains at its core an immense black hole--an object having such intense gravity that even light cannot escape. The death of stars can produce small black holes--with masses ranging from about three to 100 times the mass of the sun--but such stellar-mass black holes are tiny compared with the behemoths at the centers of galaxies, measuring millions to billions of solar masses.

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Emotion Selectively Distorts Our Recollections (preview)

Sun, 01 Jan 2012 00:00:00 EST

On September 11, 2001, Elizabeth A. Phelps stepped outside her apartment in lower Manhattan and noticed a man staring toward the World Trade Center, about two miles away. Looking up, “I just saw this big, burning hole,” Phelps recalls. The man told her that he had just seen a large airplane crash into one of the skyscrapers. Thinking it was a horrible accident, Phelps started walking to work, a few blocks away, for a 9 a.m. telephone meeting. By the time she reached her eighth-floor office at New York University, a second jet had struck the other tower, which collapsed after an hour. Later, she saw the remaining tower fall.

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Five Hidden Dangers of Obesity (preview)

Sun, 01 Jan 2012 00:00:00 EST

By now it is common knowledge that being severely overweight puts people at increased risk of suffering from heart disease, stroke and diabetes and that obesity--defined as weighing at least 20 percent more than the high side of normal--is on the rise. According to one estimate, the U.S. will be home to 65 million more obese people in 2030 than it is today, leading to an additional six million or more cases of heart disease and stroke and another eight million cases of type 2 diabetes. Many clinicians have already begun seeing families in which the grandparents are healthier and living longer than their children and grandchildren.

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Endangered Desert Microbes Protect against Coughs, Sneezes and Red Eye (preview)

Sun, 01 Jan 2012 00:00:00 EST

One fine afternoon last may, Jayne Belnap drove north out of Moab, Utah, in her beige Lexus SUV when the highway vanished. In an instant, a 100-foot-tall cloud of dust had swallowed up her vehicle. She wanted to brake, but she worried about another car slamming into her from behind. She tried to pull over, but she couldn’t see the shoulder. So Belnap split the difference: “I figured if I just crept slowly enough that I’d eventually get out of there or fall off the road.”

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Battles among Ants Resemble Human Warfare (preview)

Thu, 01 Dec 2011 00:00:00 EST

The raging combatants form a blur on all sides. the scale of the violence is almost incomprehensible, the battle stretching beyond my field of view. Tens of thousands sweep ahead with a suicidal single-mindedness. Utterly devoted to duty, the fighters never retreat from a confrontation--even in the face of certain death. The engagements are brief and brutal. Suddenly, three foot soldiers grab an enemy and hold it in place until one of the bigger warriors advances and cleaves the captive’s body, leaving it smashed and oozing.

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Can Machines Predict Where Crimes Are about to Happen? (preview)

Sun, 01 Jan 2012 00:00:00 EST

Patrolman joseph cunningham and I are hunting for criminals. not just any crooks but home burglars. And not just anywhere: although the city of Memphis covers 315 square miles, our search area has been narrowed to just a few square blocks of low brick apartment buildings in a crime-plagued part of town. The search date and time, too, have been tightly defined--Thursday, between 4 p.m. and 10 p.m. The shift begins now. “I don’t anticipate any car chases tonight, but if one happens, be sure to put your seat belt on,” Cunningham says as we pull out from the station.

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Common Brain Mechanisms Underlie Supernatural Perceptions (preview)

Sun, 01 Jan 2012 00:00:00 EST

You may have never personally caught sight of Jesus Christ’s face in a potato chip, but you have likely succumbed to an equally improbable belief at some point in your life. Many people claim that ghosts exist or that their dreams can predict the future. Some individuals even think they have seen the face of the Virgin Mary in a grilled cheese sandwich and Mother Teresa in a cinnamon bun.

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How to Make the Food System More Energy Efficient

Sun, 01 Jan 2012 00:00:00 EST

For more than 50 years fossil fuels and fertilizers have been the key ingredients in much greater global food production and distribution. The food-energy relationship has been a good one, but it is now entering a new era. Food production is rising sharply, requiring more carbon-based fuels and nitrogen-based fertilizers, both of which exacerbate global warming, river and ocean pollution, and a host of other ills. At the same time, many nations are grappling with how to reduce energy demand, especially demand for fossil fuels.

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