DiscoverNovember 2019的目錄

I’ll never forget sitting in physics class, riveted by the next challenge from Mr. Price. He reveled in getting us to visualize in our minds what’s happening when a pendulum swings or a loaded spring bounces back. He pushed us to understand the underlying equations, and then, with his infectious enthusiasm, launched us on experimentation. As someone who struggled in math classes, I loved the simultaneous abstraction and groundedness of physics. One story in this issue, for me, is kind of like being back in that physics class. Frequent Discover contributor Adam Hadhazy takes us on a romp through 10 experiments, from the third century B.C. to the mid-1900s, that changed the very nature of how we understand the world today. Most of them were successful, but even toss in…

If you speak Spanish, this word’s religious meaning is clear: penitent, or repentant. In scientific circles, though, penitentes are jagged snow formations, named after their resemblance to the white, pointed hoods once worn by some Catholics in Spain. Researchers believe they form in snowy areas where it’s sunny but still cold, like mountain peaks in the summer. Because of the dry, cold air, any snow that warms too much doesn’t melt; it vaporizes. While other factors may also play a role, it’s this vaporizing that whittles the remaining white stuff into the characteristic points of penitentes. Earth might not even be the only place you could spot them. Astronomers suspect that both Pluto and Jupiter’s moon Europa have their own versions of the peaks.…

This geometric patchwork of lush greens is a satellite shot of farmland in southwestern Kansas. At the center of each thriving circle or semi-circle lies a well. Researchers at the University of Arizona and the Colorado School of Mines are especially interested in these well-water-dependent bits of cropland, because the wells pump groundwater that normally would trickle into nearby creeks and streams before feeding into rivers. In a recent study (unrelated to this photo), the Arizona and Colorado team found that, since such large-scale groundwater pumping began in the U.S. in the 1950s, stream flows to rivers in some portions of the country have dropped by nearly 50 percent. According to the authors, knowing how we use our groundwater now can help us better manage future use to ensure we’re…

Every day, we conduct science experiments, posing an “if” with a “then” and seeing what shakes out. Maybe it’s just taking a slightly different route on our commute home or heating that burrito for a few seconds longer in the microwave. Or it could be trying one more variation of that gene, or wondering what kind of code would best fit a given problem. Ultimately, this striving, questioning spirit is at the root of our ability to discover anything at all. A willingness to experiment has helped us delve deeper into the nature of reality through the pursuit we call science. A select batch of these science experiments has stood the test of time in showcasing our species at its inquiring, intelligent best. Whether elegant or crude, and often with…

EXPERIMENTAL RESULT: DEFINING RADIOACTIVITY WHEN: 1898 Few women are represented in the annals of legendary scientific experiments, reflecting their historical exclusion from the discipline. Marie Sklodowska broke this mold. Born in 1867 in Warsaw, she immigrated to Paris at age 24 for the chance to further study math and physics. There, she met and married physicist Pierre Curie, a close intellectual partner who helped her revolutionary ideas gain a foothold within the male-dominated field. “If it wasn’t for Pierre, Marie would never have been accepted by the scientific community,” says Marilyn B. Ogilvie, professor emeritus in the history of science at the University of Oklahoma. “Nonetheless, the basic hypotheses — those that guided the future course of investigation into the nature of radioactivity — were hers.” The Curies worked together…

1 With forelimbs like clawed shovels, little or no eyesight and a penchant for tunneling, the much-maligned mole is considered a monster by many a gardener. But dig into the details of these fossorial, or burrowing, mammals, and you might envy their superpowers. 2 Take the star-nosed mole. Found throughout the northeastern U.S. and Canada, the semi-aquatic Condylura cristata has 22 symmetrical, tentacle-like appendages that sprout from its snout. 3 The wiggly, fleshy nose-fingers, or rays, have nothing to do with smell. They’re covered with 25,000 sensory receptors called Eimer’s organs that give the star-nosed mole a supersized sense of touch. 4 C. cristata can identify, capture and eat its prey, generally insects and worms, in an average of about 230 milliseconds. That’s roughly three times faster than a human driver’s…

Swimming on Air (July/August 2019) “Everything Worth Knowing: Flight” by Jonathon Keats notes that the Archaeopteryx likely used its wings similarly to the butterfly stroke of a swimmer, but states the purpose of the vertebrae running through the tail and the asymmetrical tail feathers remains a mystery. Having once been a competitive swimmer, I think the answer to the purpose of the Archaeopteryx’s tail seems obvious — it used it like a swimmer’s dolphin kick. A swimmer uses two dolphin kicks to every one butterfly stroke with the arms. Why couldn’t the Archaeopteryx do the same to propel it through the air? It could also turn the tail slightly to direct the flight’s direction and, when soaring, the tail could be used to aid in ascending and descending, just like…

IN THE LATE 1990S, geneticists began studying extinct species’ DNA, analyzing hair and bone preserved in frozen tundra. At that time, most computers stored data on floppy disks that held just 1.44 megabytes of memory — smaller than the average selfie. Today, those disks might as well be Ice Age artifacts, too. Not only is their storage capacity miniscule by today’s standards, but recovering their data is practically impossible, due to the degradation of their materials and the special equipment required to read them. The floppy disk encapsulates some of the greatest long-term challenges to computer science. According to Microsoft principal researcher Karin Strauss, future storage will need exponentially greater density to hold the data we produce as electronic devices become a greater part of our lives. Plus, long-term archiving…

In an effort to tackle climate change, dozens of countries, responsible for 55 percent of global emissions, came together to sign the Paris Agreement in 2016. The pact, which at least 185 countries have now signed, aims to limit the global temperature rise to 2 degrees Celsius (3.6 degrees Fahrenheit) — or even more ideally, to 1.5 C (2.7 F) — and to help countries deal with the impacts of climate change. In an abstract sense, we all know how important that goal is, but one recent study in Science Advances highlighted just how life-and-death the stakes are. In major cities, extreme heat events would prove much deadlier with higher global temperatures. Lives lost and saved, per single extreme heat event* *Extreme heat events will differ by locale and average…

Plants need the element nitrogen to grow, but they can’t use the nitrogen that’s in the air. Legumes, members of the bean family, get around this problem by providing a home for nitrogen-fixing bacteria in nodules on their roots.…

Beneficial microbes introduced to plants, seeds or soil are known as biofertilizers. The effect of a specific microbe varies from plant to plant — the same bacteria that might help a pea plant fix nitrogen won’t work the same way in corn. However, researchers have discovered pairings that do seem to work.…

EXPERIMENTAL RESULT: THE FIRST RECORDED MEASUREMENT OF EARTH’S CIRCUMFERENCE WHEN: END OF THE THIRD CENTURY B.C. Just how big is our world? Of the many answers from ancient cultures, a stunningly accurate value calculated by Eratosthenes has echoed down the ages. Born around 276 B.C. in Cyrene, a Greek settlement on the coast of modern-day Libya, Eratosthenes became a voracious scholar — a trait that brought him both critics and admirers. The haters nicknamed him Beta, after the second letter of the Greek alphabet. University of Puget Sound physics professor James Evans explains the Classical-style burn: “Eratosthenes moved so often from one field to another that his contemporaries thought of him as only second-best in each of them.” Those who instead celebrated the multitalented Eratosthenes dubbed him Pentathlos, after the…

Jonathan Flint grew up surrounded by the notion of suicide. The bookshelves in his childhood home in London were filled with tomes on the subject, as well as on bereavement and counseling. His mother was an early volunteer at one of the first suicide prevention hotlines, and the friends she brought home were involved, too. He even accompanied her one afternoon while he was a university student, and talked to anguished people who had lost all hope. In the U.S., suicide rates have jumped 33 percent in the past two decades. Witnessing the devastation when one of his family members attempted to take their own life had a profound effect on him. Flint’s pursuit of psychiatry was a natural choice, he says now, but he also gravitated toward figuring out…

Back to the Moon Vice President Mike Pence announced March 2019 that the Trump administration wants to put humans back on the moon within five years. The mission would focus on the moon’s South Pole, which remains relatively unexplored. But with NASA’s financial setbacks and the current political climate, it might be more wishful thinking than anything. We asked our fans on Facebook: Do you want to see the U.S. return to the lunar surface? Mellanie Nelson Robles: I want investments in schools and crumbling infrastructure, I want a Green New Deal — so many issues have a higher priority! Francesk Nikolli: Everyone is saying that the money can be spent better on health departments or other things on Earth, and they’re right. But this kind of research is also…

Spotting the Signals A recent New England Journal of Medicine study says that electroencephalogram (EEG) machines can pick up brain signals that could hint at consciousness in unresponsive patients who’ve suffered brain injuries. Detecting these super faint signals isn’t new — previous work using functional magnetic resonance imaging (fMRI) has spotted them, too. But EEGs are portable and cheaper than fMRI machines. Out of the 106 patients the researchers worked with, an EEG was able to detect signals in 16 of them. The study’s authors hope their advancement will help medical staff identify those with the best hope of recovery so their families can make more informed decisions about life support. A Problem-Solving Protein The fight against malaria is tricky. Mosquitoes of the genus anopheles, the only carrier of the…

Two holes in the ice caught Sue Dickerson’s attention when she checked a black plastic water dish in her yard one morning in February 2018. The temperature had dropped to 18 degrees Fahrenheit overnight, so it didn’t surprise her that the top layer of water in the dish had frozen. But what had made those holes? She studied them for a moment. “Flickers,” she thought to herself. The woodpeckers often hung out in her Colorado Springs, Colorado, front yard and had likely pecked through the ice to get a drink. Dickerson, who had stepped outside to grab the photo card from the motion-activated camera she’d set up near the dish, crouched, hooked her index finger into one of the holes and tossed the ice. Back inside, she settled in front…

For centuries, growers relied on manure and crop rotation to keep soil fertile. But in 1908, German chemists Fritz Haber and Carl Bosch invented a way to transform nitrogen gas and hydrogen into a liquid chemical — ammonia — that could be sprayed onto soil to make it almost instantly fertile. Relatively cheap to produce and easily mixed with other nutrients like phosphorus, potassium and sulfur, this new way to fertilize sparked an agricultural revolution. Crop yields skyrocketed 30 percent to 50 percent. So did the world’s population, which went from 1.65 billion in 1900 to 7.6 billion today. Fertilizer use comes at a cost, though. Manufacturing it produces 3 percent of the world’s carbon emissions. Most commercial farmers in the U.S. apply between 160 and 220 pounds of mainly…

When the Hooker Telescope first looked skyward in 1917, no one knew what wonders it might reveal. Within a decade, astronomer Edwin Hubble used it — then the largest telescope in the world, at 100 inches across — to discover that galaxies exist beyond the Milky Way, and that the universe is expanding. History repeated itself starting in 1949, when the 200-inch Hale Telescope took its first photograph of the night sky. In the early 1960s, astronomer Maarten Schmidt used the instrument to analyze unusual, “quasi-stellar radio sources”—quasars for short. These turned out to be supermassive black holes accreting matter in the centers of galaxies, a science-fiction fantasy when the Hale Telescope was built. By the 1990s, technology advanced far enough to usher in an era of telescopes 8 to…

EXPERIMENTAL RESULT: THE DISCOVERY OF BLOOD CIRCULATION WHEN: THEORY PUBLISHED IN 1628 Boy, was Galen wrong. The Greek physician-cumphilosopher proposed a model of blood flow in the second century that, despite being full of whoppers, prevailed for nearly 1,500 years. Among its claims: The liver constantly makes new blood from food we eat; blood flows throughout the body in two separate streams, one infused (via the lungs) with “vital spirits” from air; and the blood that tissues soak up never returns to the heart. Overturning all this dogma took a series of often gruesome experiments. High-born in England in 1578, William Harvey rose to become royal physician to King James I, affording him the time and means to pursue his greatest interest: anatomy. He first hacked away (literally, in some…

Nowadays, you can sequence your genome in a weekend for about a thousand bucks. But would you believe that the first human genome sequenced took 13 years (1990 to 2003) and cost $2.7 billion? Back in those days, when Harry Potter had just started his on-screen adventures at Hogwarts, getting your genome sequenced was a rare privilege. Among the first people to remove the invisibility cloak from their DNA were James Watson, one of the scientists who helped solve the structure of DNA in 1953, and Craig Venter, who was instrumental in making the Human Genome Project happen. Steve Jobs was also one of the first to have his genome sequenced (which I imagine lab techs referred to as the iGenome). What other luminaries did scientists reach out to for…

Around the world, more than 300 million people have depression. In the U.S., more than 8 percent of adults are diagnosed with the disorder, which affects men and women at different rates. Percentage of adults age 20 and over with depression BOTH SEXES 8.1% 20-39 7.7%40-59 8.4%60 and over 8.0%MEN 5.5%20-39 5.5%40-59 5.2%60 and over 6.1%WOMEN 10.4%20-39 10.1%40-59 11.5%60 and over 9.6% Percentage of adults age 20 and over with depression, by family income level (In 2019, Federal Poverty Level was $25,750 for a family of four.) BOTH SEXES Less than 100% of FPL 15.8%100%-200% 10.9%200%-400% 7.8%400% or above 3.5% MEN Less than 100% 10.8%100%-200% 7.3%200%-400% 6.1%400% or above 2.3% WOMEN Less than 100% 19.8%100%-200% 13.9%200%-400% 9.4%400% or above 4.8% Percentage of adults age 20 and over with depression who…

Ask The Expert The Art Of Aging Well! A Secret Any Man Can Use… This month, I got a letter from a reader in Arizona about a “little secret” that’s completely reignited her husband! Kathy writes: Dear Mike, For years my husband and I had a great marriage. He was smart, outgoing and his sharp wit kept us all laughing. He had such a passion for life but when he reached his 50s, he really slowed down and lost his spark. No matter what I suggested, he was “too tired.” He became forgetful, indecisive, and irritable. He even stopped working out, complaining about his aches and pains. He lost the playfulness that I loved so much and most days it seemed like he was just going through the motions. I…