During the Second World War, airmen introduced the term “he bought the farm” after a pilot was shot down. The expression caught on with all the armed services and meant that if you gave your life for your country, your impoverished family would receive insurance money for your death, which would help pay off the mortgage on the family farm. Death for your country meant you were “buying the farm” for your parents.
The word Utopia was created by the English philosopher Sir Thomas More in 1516 and was the title of his book that compared the state of life in Europe at the time with an imaginary ideal society. Utopia is from Greek meaning nowhere.
The thrust of More’s message was that an ideal world, or Utopia, will never exist, and that our only choice is to improve the standards of our existing society.
About one-tenth of Earth’s surface is always under the cover of ice. And almost 90 percent of that ice is found in the continent of Antarctica. The remaining 10 percent is found on the mountains in the form of glaciers.
The ice sheet that covers Antarctica is almost one-and-a-half times the size of the United States.
The Japanese word tsunami (pronounced soo-NAH-mee) means “harbor wave.” It is a huge volume of moving seawater—kind of like a giant wave—that can travel for thousands of miles across the sea and then approach the shoreline with the strength to destroy buildings, trees, wildlife, and people. Tsunamis can be triggered by an undersea earthquake, landslide, or volcanic eruption. The most frequent tsunami-maker is an undersea earthquake, which buckles the seafloor and displaces large volumes of seawater, creating a tsunami. This unique ocean event is not related to tides, although it is sometimes mistakenly called a tidal wave.
“Hanging out” usually means getting together for no particular reason other than to pass time and see what’s happening. The expression comes from a time before commercial signs, when English shopkeepers set up poles in front of their stores from which they would hang flags describing their goods. These flags were called hangouts, and they became a place where people would stop to linger and gossip with their friends.
Potato chips often contain saturated fats, which over time can clog the arteries that carry blood to the heart. The oils used to cook the chips are made up of saturated fats, which increases cholesterol production in the body, a known risk factor for heart disease.
Heart disease results from a condition known as atherosclerosis, which happens when a waxy substance forms inside the arteries that supply blood to your heart.
The classic tale of Dorothy in the land of Oz came from the imagination of L. Frank Baum, who made up the story for his son and a group of children one evening in 1899. When a little girl asked him the name of this magical land with the Scarecrow, Tinman, and Cowardly Lion, he looked around the room for inspiration. He happened to be sitting next to a filing cabinet with the drawers labelled “A-G,” “H-N,” and finally “O-Z,” which gave him a quick answer: “Oz.”
Scientists estimate that Earth—born out of a swirling cloud of gas and dust—is about 4.6 billion years old. They have reached this conclusion by studying Moon rocks and meteorites (rocks that have fallen from space to Earth) that they believe were formed at the same time as our planet.
An ear thermometer reads the spectrum of thermal radiation given off by the inner surfaces of a person’s ear. All objects give off thermal radiation (including the light emitted by a glowing incandescent light bulb) and that radiation is characteristic of their temperatures. The hotter an object is, the brighter its thermal radiation and the more that radiation shifts toward shorter wavelengths.
The thermal radiation from a person’s ear is in the invisible infrared portion of the light spectrum, which is why you can’t see people glow. But the ear thermometer can see this infrared light and it uses the light to determine the ear’s temperature. The thermometer’s thermal radiation sensor is very fast, so it can measure a person’s body temperature in just 168 a few minutes.
It bends because it is made of two metals that are joined together, something called a bimetal switch. One metal (usually brass) expands quickly when heated, while the other expands much more slowly. This difference causes the switch to bend toward the low-expansion metal.
Bimetal switches are used in other appliances that switch electricity on and off to keep their temperatures even, like irons and refrigerators. The thermostat that regulates the temperature of your home by turning your furnace and air conditioner on and off also uses a bimetal switch.