APC Science Union · Online Library

Author: Guanfu · Juntian   Every summer and fall, violent storms known as typhoons form over the northwestern Pacific near China. Some dissipate at sea, while others make landfall with fierce winds and torrential rain. Where do typhoons come from? Where do they go? And why do they have such a powerful effect on China? Here is a short introduction.   What exactly is a typhoon? It is a type of tropical cyclone: a rotating storm system that forms in the tropics. Tropical cyclones are classified by wind strength into tropical storms, severe tropical storms, typhoons, and other categories. How Does a Typhoon Form?   A typhoon needs three conditions to form.   The first is moisture. The ocean provides a steady supply of water vapor.   The second is heat. Strong summer sunlight allows water va ...

Author: Star Life Reviewer: Abaiter   Under good conditions, a glance at the night sky reveals a vault full of stars. To understand these celestial objects, people observe and measure them, then use the resulting data in theoretical calculations. The branch of astronomy devoted to observing stars, planets, deep-sky objects, and other bodies in the universe and obtaining the quantities needed for those calculations is called astrometry. Today, let us look at how astronomers measure the distances to stars.   Stars lie at different distances from the Sun, but all of them are extremely far away. The ordinary units of length we use on Earth are impractical for stellar distances, so astronomers use other units instead. One is the light-year, the distance light travels through a vacuum in one y ...

Theory in the Natural Sciences: A View from Chemistry Author: Dclean Reviewers: 黍离, 白書, and 一毫秒的永恒   Human understanding of nature begins with observing natural phenomena. The immediate impressions left by those observations became some of the earliest “knowledge” in human history. In pursuit of deeper understanding, people gradually classified and organized that knowledge, connecting it through logic. From this process came the first rudiments of “theory.”   This article considers how science understands theory, the role of theory in the natural sciences, and the relationship between theory and practice. Part I | How Disciplines Differ: Subject Matter and Method   We often ask what truly distinguishes physics from chemistry. We also hear claims that chemistry is merely a branch of phys ...

Translators: 时光, 东达, JJ Proofreader: 毫秒 Reviewer: 毫秒 So Sour!   Before we begin, imagine a little game: someone gives you a lemon. Cut it open, then eat it without changing your expression.   Could you do it? If not, that is exactly the point. (If you could, just pretend you could not!) The question we want to explore is why a lemon’s sourness has the power to twist your face into such a dramatic grimace. Sourness makes me pucker. | Credit: Shutterstock   Scientists are not entirely sure, but they think the answer involves three things: hydrogen ions, vitamin C, and our ancestors’ experience of feasting on tropical fruit up in the trees.   The taste we call “sour” is directly connected to acidity. In chemical terms, sourness is your taste buds saying, “There are a lot of hydrogen ions ...

Author: A Millisecond of Eternity   Thousands of years ago, our ancestors set up milestones, drew detailed maps, and learned to navigate by the night sky. Things are much easier now. A smartphone handles most everyday navigation, and with a GPS receiver, you can locate yourself almost anywhere satellite signals reach. Getting lost is no longer much of a worry.   What follows is a brief introduction to GPS positioning. The Global Positioning System is enormous, expensive, and complex, but the basic ideas behind it are surprisingly simple and intuitive.   The Global Positioning System, or GPS, provides accurate positions, velocity measurements, and highly precise standard time across most of Earth’s surface. In everyday conversation, “GPS” usually means the receiver in your device. In spac ...

Author: A Millisecond of Eternity A frame from the miniseries *Chernobyl* showing helicopters dropping sand and boron onto the reactor core | Credit: HBO   I recently heard about HBO’s acclaimed miniseries Chernobyl and decided to watch it. The plotting, cinematography, and sound design are all exceptionally well done. Although viewers already know how the disaster ended, the series still makes its oppressive, tragic atmosphere deeply affecting. Its reconstruction of the 1986 Chernobyl nuclear disaster is remarkably convincing, and I recommend it to anyone interested in the subject.   Most readers will know at least something about the 1986 Chernobyl disaster, the worst nuclear catastrophe in human history. Estimates suggest that it released more than 400 times the radioactive material ...

Author: 张贤 John Watson   When people hear the advice that a child who falls should not be helped up, many think of the American psychologist John Watson. His method of making babies “immune to crying” was once enormously popular. Its central rule was simple: do not pick up a child who is crying; wait until the crying stops. As the delay grew longer, the child would supposedly stop fussing and become a self-reliant, independent “perfect child.”   The theory still has many adherents, but from the perspective of modern psychology, it rests entirely on a misunderstanding of human nature.   Research indicates that when an infant’s cries are repeatedly ignored, the infant’s brain releases high concentrations of cortisol, a stress hormone. Prolonged psychological stress of this kind may damage ...

Author: A Millisecond of Eternity Near-Earth asteroid Apophis (yellow orbit) will pass Earth in 2029, coming closer than some artificial satellites (blue dots). The purple line marks the orbit of the International Space Station. | Credit: NASA/JPL-Caltech   On April 13, 2029, a speck of light in the sky will grow brighter and move faster. At one point, it will cross more than the apparent width of the full Moon in a single minute and shine about as brightly as the stars of the Big Dipper. The object will be neither a satellite nor an airplane, but the roughly 340-meter near-Earth asteroid (99942) Apophis. It will skim past Earth about 31,000 kilometers above the surface, closer than some artificial satellites; geosynchronous satellites orbit roughly 36,000 kilometers above the equator. ...

Author: 一毫秒的永恒 A few decades ago, astronomers could only dream of glimpsing the Moon's other side. This is a NASA visualization. | Credit: NASA's Scientific Visualization Studio   Look up at the bright Moon: it seems as familiar as ever, no different from the Moon of the past. Indeed, the Moon you admire is the same one our ancestors admired. After sunset, people around the world can see those same familiar shadows and shapes. It is easy to understand why ancient poets used the Moon to express their longing for home and family.   From ancient times until the modern era, people on Earth could see only the Moon’s “near side.” Humanity did not glimpse the “far side” until 1959, when the Soviet Luna 3 spacecraft flew around the Moon and sent back photographs. In 1959, the Soviet Luna 3 pro ...

Author: A Millisecond of Eternity   In the early hours of April 24, 019, a magnitude 6.3 earthquake struck Medog County in Nyingchi, Tibet. The shaking was widely felt across the surrounding area, but fortunately, very few people lived within 50 kilometers of the epicenter, and no casualties were reported.   Earth has earthquakes, but do other worlds in the Solar System “quake” too? Of course. Consider our own Moon. In 1969, American astronauts first set foot on the lunar surface during the Apollo program and installed 5 seismometers. The instruments continuously transmitted records of moonquakes to Earth, opening a new field of lunar seismic research. In 2019, scientists found signs of quakes on our neighbor Mars as well. Marsquake signal detected by SEIS   The InSight lander’s Seismic ...