When Kea hi Seymour was 12 years old, he watched a television show about kangaroos . He learned that these animals store energy in the long, stretchy tendons attached to their huge feet. Hitting the ground stretches the tendon like a rubber band, storing the energy from the impact. When the animal lifts off, the energy gets released, like a snapping rubber band, giving an extra boost of speed and power.
像鸵鸟一样快——新发明如何由观察自然界而来 Continue reading »
You toss some bananas and milk into a blender. Then you plug it into the wall and press start. Soon, you have a delicious smoothie. While you’re sipping and scrolling through TikTok, you notice your phone’s battery is low. So you plug that into the wall and the battery charges.
Next time you step outside, take a moment to notice all the plants. You may see a grassy lawn, weeds poking through the sidewalk, towering trees, moss growing on rocks or bricks, or maybe even a vegetable or flower garden. Now let this thought sink in: without plants, you and all the other human beings and animals on this planet couldn’t survive. We depend on plants for the air we breathe. But the relationship goes much deeper than that. We also rely on plants for food, clothing, medicines, materials, and so much more.
Just as you can write the history of the world using the biographies of the famous men and women who changed it (Confucius, Alexander the Great, Queen Elizabeth, Winston Churchill, etc.), you can tell the story of humankind by going from one great cultural center to another. Certain cities at certain moments have defined the course of the arts . Consider Xi’an in the Tang dynasty, Florence and Amsterdam in the Renaissance, London in the time of Shakespeare, or Vienna during the era of Mozart, Haydn, and Beethoven. In exactly this way, Paris during the Jazz Age was one of the most fun and one of the most important cities in the history of art, music, literature, and fashion.
At the end of the story Charlie and the Chocolate Factory by Roald Dahl, the eccentric inventor and candy – maker Willy Wonka takes young Charlie Bucket into a glass contraption that he calls a Wonkavator. It bursts through the roof of the factory and flies them out over the city. Willy Wonka says, An elevator can only go up and down, but the Wonkavator can go sideways, and slantways, and longways, and backways, and squareways, and frontways, and any other ways that you can think of.
Wild nature seems to be the opposite of a human city. In nature, curvy and messy lines dominate, while in a city, most lines are straight and neat. In nature, the weather changes from rain to heat to cold, while in a city, roofs and heating and cooling systems keep people comfortable. In nature, growth happens chaotically, while in a city, growth is planned and controlled. In a city, people often pave over nature or fence it in. They tame it to the point that it may be hard to notice. But nature is always there. In fact, it is essential.
When you think of a city, you probably think of busy streets and towering skyscrapers . But the city doesn’t just reach up into the sky. It also extends down below the earth. Hidden beneath buildings and roads, a complex network of wires and pipes brings residents electricity, water, and gas and also removes their waste. Underground tunnels house subway systems, storage rooms, or other structures. In many cities, space above ground is so precious and crowded that engineers are finding new, creative ways to use underground space. Singapore is one of those cities. Here, the underground is already used for many purposes, and the city government is looking into ways to build even more underground structures. “You can build up, but there is a limit,” said John Keung when he was CEO of Singapore’s Building and Construction Authority. “The only thing left is to go underground.”
The next big thing in nuclear energy is small. Designs for dozens of small modular reactors have been developed or are in progress . And a few small reactors are already operating in India, Pakistan, Russia, and elsewhere. A small modular reactor can produce up to 300 megawatts (MW) of electricity (many designs produce much less). But size isn’t the only thing that makes these new, advanced reactor designs stand out.
Everyone can see that, from birth through adolescence, humans get taller and their bones get longer. And then all th at stops around the end of the teen years. In the past, the mechanism of growth was a mystery. In the fourth century, there was a common belief that children’s natural character was hot and liquid, partly because of the blood that went into their creation. Thus, a physician to the Roman emperor believed that children grew because of their excessive heat. Twelve hundred years later, it was understood that food provided the material that allowed growth. A French physician, however, pointed out that even when sick children didn’t eat, they continued to grow.
