DiscoverSeptember 2018的目錄

In November 1983, the specter of nuclear warfare landed in our living rooms. I was a middle schooler, and many of my friends and their parents were keyed up for The Day After. The made-for-TV movie would hold millions in rapt attention as nuclear fallout spread radiation sickness through a Kansas community. I vividly remember gathering in front of our small black-and-white TV in the basement, and I was thankful it was on the station that came in clearly. (The big antenna out in the woods near our house pulled in exactly three channels.) That one night had nuclear weapons front and center for over 100 million Americans. It was my generation’s duck-and-cover drill. For kids in Montana, like me, it was another reminder that missile silos were sitting, waiting,…

IN 2008, Discover profiled amateur archaeologist Sam Osmanagich, who claimed to have discovered the oldest and largest pyramids in the world. Located near the Bosnian city of Visoko and billed as “the most monumental construction complex ever built on the face of the planet,” the pyramids were allegedly made by a highly advanced civilization some 12,000 years ago. While Osmanagich had no evidence, he did gather worldwide media attention, hundreds of volunteers aiding his excavation and legions of visitors to his so-called “pyramid valley.” The Bosnian government was thrilled with the boost in tourism and national pride, both welcome after the devastating Bosnian war of 1992-95. Osmanagich was a national hero. The only problem was that the experts didn’t believe him. In 2006, the European Association of Archaeologists wrote an open…

Paul speaks no English, only Portuguese. Through a translator, he says with a sneer that his wife, Janet, called the ambulance. “I am fine,” he says. “You need to let me go home.” He curses in Portuguese. →Paul arrives at the emergency department by ambulance. Paramedics wheel in the 70-year-old on a stretcher and help him sit on the edge of a bed. He’s wearing an oversized T-shirt and paint-splotched pants. His arms are crossed, and he’s staring at his shoes, as if giving the room the silent treatment. Paul speaks no English, only Portuguese. Through a translator, he says with a sneer that his wife, Janet, called the ambulance. “I am fine,” he says. “You need to let me go home.” He curses in Portuguese. Since yesterday, Paul has…

The bomb arrived in pieces. Workers assembled the device behind steel-reinforced concrete walls in the desert, mating radioactive materials with high explosives. It was called Kearsarge. And on a hot August day in 1988, a crew lowered the bomb through a hole drilled thousands of feet into the Nevada Test Site, then entombed it beneath millions of pounds of sand. Thirty miles away, Los Alamos Director Siegfried Hecker sat nervously in the control room. Seven top Soviet nuclear scientists watched intently. What if the bomb fizzled, Hecker thought. What happens to America’s nuclear deterrent? Officials had negotiated this Joint Verification Experiment for years. The United States and Soviet Union had long conducted test explosions of the bigger weapons in their arsenals, both to make sure they really worked and as…

Massively parallel supercomputers simulate seemingly impossible problems — global climate models, nuclear blasts — by breaking them into chunks and working on each at the same time. For example, in 2012, Los Alamos’ Cielo supercomputer simulated nuking an asteroid by first dividing the space rock into millions of small cubes, groups of which were assigned to different processors. Then Cielo ran through the nuclear explosion, millisecond by millisecond, to determine each cube’s immediate fate. They’ll need an exascale machine to fully solve the problem, though. These big simulations, sometimes called hero calculations, need weeks or months to code, and just as long to run. “It’s about the hardest thing we can do,” says Los Alamos’ John Sarrao. “It’s heroic when it works.”…

What Can’t Be Done? (“Whatever Happened to the Future?” June 2018) This is a terrific article that I read with great interest. I am a licensed pilot with a degree in aeronautical engineering. I supervised 50 design engineers on the Apollo backpack used on the moon. When I was a kid in Brookfield, Massachusetts, in the 1940s, the old-timers told me the moon was made of blue cheese and that going there was inconceivable. Well, it turned out that we did it in my lifetime and that I worked on it! The next challenge for humans is to exceed the speed of light. Your article points out that, currently, impossible technology is needed. No problem! Humans are always thinking about and working on the next impossible barrier. Hampden, Mass. Feedback…

ALONG ANTARCTICA’S west coast near the Amundsen Sea, great white glaciers the size of U.S. states slowly slide into the ocean. In the early ’80s, scientists dubbed it the continent’s “weak underbelly” after learning that ice here — which helps hold back the entire West Antarctic Ice Sheet — is anchored below sea level. If oceans warmed, this unfortunate topography could cause rapid and irreversible retreat. In decades past, glaciologists had assumed these ancient features advanced and retreated on epic time scales — not in human lifetimes. Ever since, climatologists have been spellbound watching the rapid changes. We now know that melting the whole West Antarctic Ice Sheet could cause 15 feet of global sea level rise. And that’s galvanized the scientific community, leading to a new $50 million joint…

Quantum computers operate on units of information called qubits, instead of a classic binary computer’s bits. But they make mistakes when exposed to heat. So IBM built this gold-plated device, called a dilution refrigerator, to cool its 50-qubit processor to a temperature of just a fraction above absolute zero. When properly chilled, the processor can crunch massive numbers in lightning-fast time and solve extraordinarily complex problems that would bog down traditional computers.…

Nuclear warheads are like avocados. They’re similarly shaped with an inner core, called a pit. The bomb’s typically grapefruit-sized pit is often hollow and lined with plutonium. Instead of delicious green fruit surrounding it, the warhead has high explosives aimed inward, to create an implosion. This squeezes the plutonium pit until it’s so dense that particles start smashing into plutonium nuclei, literally splitting atoms and unleashing their incredible energy. That simple design worked for Fat Man (above), detonated in Nagasaki in 1945. But today’s stockpiled warheads are thermonuclear devices, commonly called H-bombs because they use hydrogen. These have a secondary stage — like a second pit next to the plutonium pit. As the first pit erupts in a nuclear explosion, its radiation bounces off the hardened shell of the second…

Supercomputer history can fit into three eras, says Horst Simon, deputy director of Lawrence Berkeley National Laboratory. “If you want to chop down the Amazon rainforest, you can have one chain saw, 100 beavers, or you can use 1 million ants,” he says. The chain saw represents early supercomputers — expensive and high-powered, but capable of only felling one tree at a time. Beavers work longer per tree, but chew on 100 simultaneously, so they’re ultimately more productive. That’s the massively parallel supercomputers, which dominated until recently. Now the industry is pushing toward ants — the tiny components of exascale computers. They’re abundant, use little energy and can accomplish the task more quickly.…

Scourge of the South (“A Deadly Diet,” March 2018) In the early 1900s, physicians fought a recurring battle in the American South, against a disease called pellagra. It turns out corn-based diets were to blame for the condition, which was marked by symptoms including diarrhea, dementia and even death. Here’s what some of our online readers thought of our dive back into medical history: Jason Tormund: It isn’t that the corn/grains caused the disease, but rather that those foodstuffs alone lack key nutrients needed by people, and when poor people sustain primarily on a nutrient-lacking diet, they’re going to have problems due to malnutrition. Atlanta_Girl: Imagine if the molasses or cornmeal industry had sponsored the research back then……

NO, IT’S NOT AN ALIEN ARTIFACT. Since 1998, the Sloan Digital Sky Survey (SDSS) has used thousands of metal disks like this — called plug plates — to map the universe. Workers called plate pluggers clamp these disks atop a 2.5-meter telescope in New Mexico, after threading optical cables into the hundreds of holes. Each one lines up with the light from a known galaxy or star. This creates, in effect, an armada of tiny telescopes, each hyper-focused on a single celestial sight. Now in its fourth phase, SDSS has mapped the Milky Way in 3D, surveyed millions of nearby galaxies, and more. It’s like Google Earth for the cosmos. Along the way, the plates themselves have become iconic, recycled into coffee tables, museum pieces, even fine art sculptures. But…

The Big Picture Want to stay busy? Try taking a head count of all the life on Earth. That’s what researchers from the Weizmann Institute of Science in Israel and the California Institute of Technology did, picking through hundreds of studies to conduct a global census. They dug up some interesting stuff: Of the approximately 550 gigatons of carbon (Gt C) life that inhabits our planet, plants take up the biggest chunk, accounting for 450 Gt C. The team also found that the combined biomass of humans and livestock far outweighs the biomass of wild mammals, pointing to the impact our species has had on the biosphere. Source: “The biomass distribution on Earth,” Proceedings of the National Academy of Sciences, 2018 “For the first time, we can really study those…

Certain people are more coincidence-prone than others, but all of us can learn how to cultivate them. “The more you notice the events, the more they happen,” says mathematician David Hand. Want the world to feel like a more magical place? Try these strategies: 1. Pay attention. Coincidences happen to people who are mindful and notice things. When you go about your daily activities, keep your senses open to coincidental opportunities. 2. Talk to strangers. According to work by risk researcher David Spiegelhalter, coincidences often arise out of talking to someone you don’t know. If you don’t introduce yourself to your neighbor, you can’t possibly know both of you were born in the same hospital, on the same day, in a city several hundred miles away from your current homes.…

Even at the Cold War’s peak — with John F. Kennedy suggesting families build fallout shelters — many Americans doubted we’d ever be nuked. And if it happened, most assumed we’d die in the global Armageddon. So, how do you prepare people for an improbable and seemingly unsurvivable disaster? That’s still a problem for emergency managers, says Alex Wellerstein, a nuclear bomb historian at the Stevens Institute of Technology in New Jersey. A couple of years ago, he pitched a project to re-examine how to talk to Americans about preparedness and the risk of nuclear threats. At first, his team struggled to attract interest — until 2017. After North Korea’s missile tests, suddenly even the Federal Emergency Management Agency was asking for training help. But Americans — or their government…

It all started back in 1986, with an impromptu gathering of around a dozen friends on a San Francisco beach. Burning Man co-founders Larry Harvey and Jerry James had transformed a pile of scrap lumber into an 8-foot-tall wooden figure that was doused in gasoline and set ablaze. As the crowd of curious onlookers grew, they realized they had the makings of a community. In 1990, what became known as Burning Man moved to its current home in Nevadas Black Rock Desert for the first time, where 350 participants watched a 40-foot wooden figure reduced to ash. As the attendance grew over the years, so did the man, towering as high as 105 feet.…

When it comes to species, says biological anthropologist Rebecca Ackermann, “forget everything you learned in high school.” The classic textbook definition, known as the biological species concept, is a group of organisms that only produce fertile offspring with one another. By this rule, domesticated dogs are a single species — whether dachshund or Great Dane — but a donkey and a horse are not. Ackermann, a professor at South Africa’s University of Cape Town, favors a different definition that’s not dependent on successful sex: a group of organisms sharing a mix of anatomical, behavioral and genetic traits that distinguishes them from other groups. But, she adds, “Many, many evolutionary biologists I know often avoid the word species entirely.” That’s because the evolutionary tree is tangled, and many organisms on diverging…

1 It’s touted as a miracle material, promising everything from space travel to better hair, but there isn’t much to graphene — literally. It’s a single layer of carbon atoms arranged in a repeating honeycomb-shaped pattern. 2 Graphene has great flexibility and strength, and because it’s essentially two-dimensional, electricity flows across it so quickly that it’s one of the most conductive materials known. 3 You’d be forgiven for not knowing much about it, however. Graphene had long been theorized, but it was only in 2004 that physicists Kostya Novoselov and Andre Geim proved graphene could exist on its own without being chemically bonded to other elements. 4 Just six years later, Novoselov and Geim won the Nobel Prize in Physics for their work. Also in that short span, researchers around…