Every What If? Lab

349 to explore · page 3 of 8

• Watch What If? Lab What if cities floated on the sea? Floating buildings already exist: in Rotterdam, in the Netherlands, a three-story office floats in a harbor on concrete pontoons. Designers have also planned a floating neighborhood off Busan, South Korea, for up to 12,000 people. But a floating city would need to stay afloat, cope with waves and storms, and find fresh water in the middle of salty sea. Explore each challenge.
• Watch What If? Lab What if cities had no traffic lights? Traffic lights share a busy crossing by giving each direction a turn. In this thought experiment, imagine a city without them. Would drivers take turns by the rules of the road, would roundabouts do the job, or could smarter signals help?
• Watch What If? Lab What if clouds were made of candyfloss? Puffy clouds look like giant balls of candyfloss (cotton candy), but they are really made of tiny water droplets or ice crystals, and the water in a big one weighs about as much as 100 big African elephants. Imagine clouds spun from sugar instead, and find out what real clouds are made of.
• Watch What If? Lab What if cold wind blew over a warm lake? In late fall and winter, the Great Lakes are often much warmer than the freezing air that often blows in from Canada. As cold wind crosses the open water, it picks up warmth and moisture, rises and builds narrow bands of clouds that can drop 2 to 3 inches of snow an hour, while a town a mile or two away stays sunny. This thought experiment follows the air across the lake.
• Watch What If? Lab What if colors never faded? Leave a bright poster in a sunny window and, over weeks, its colors grow pale. Light slowly changes the colored molecules in dyes and inks. Imagine a world where colors never faded, and follow the clues: sunlight, paints and blocking ultraviolet.
• Watch What If? Lab What if concrete could heal its own cracks? Concrete is strong, but it cracks, and water creeping into the cracks can rust the steel inside. Scientists are testing concrete that seals its own cracks, using sleeping bacteria or special lumps of lime. Follow the clues to see what self-healing concrete might change.
• Watch Try it What If? Lab What if concrete had no steel inside? Concrete is very good at being squashed but bad at being stretched, and a bent beam is stretched along its bottom. In our model, a 20-meter beam of plain concrete with no steel inside cracks under a 20-tonne truck, and it cannot even hold up its own weight.
• Watch What If? Lab What if coral reefs could be regrown? Scientists grow broken pieces of coral in underwater nurseries, then plant them back on damaged reefs. Follow how coral gardens work, how scientists search for corals that cope with heat, and what happens when fish come back to a restored reef.
• Watch What If? Lab What if cows could not digest grass? A cow's own body can't break down the tough stuff in grass. Tiny microbes living in its huge stomach do it instead, and the cow chews its food twice to help them. Imagine those helpers gone and follow what might change.
• Watch What If? Lab What if dinosaurs still lived today? Most dinosaurs died out 66 million years ago, after a huge asteroid hit Earth. One group survived: birds, which scientists count as living dinosaurs. Imagine the other dinosaurs had survived too. Where could they live, what would they eat, and how would they fit into today's world?
• Watch Try it What If? Lab What if Earth had no atmosphere? Earth's air works like a jacket: it keeps heat in and carries it around. Take the air away in our model of a sandy patch of ground on the equator, and the coldest part of the night drops from about 13 °C to about 2 °C.
• Watch What If? Lab What if Earth had no deserts? About one third of Earth's land is desert. Deserts form where sinking air dries out the sky or mountains block the rain, and they are home to animals found nowhere else. Their dust even blows across an ocean to feed the Amazon rainforest. Imagine Earth with no deserts and see what would change.
• Watch What If? Lab What if Earth had no magnetic field? Deep inside Earth, swirling melted iron makes a magnetic field all around our planet. It turns compass needles, helps sea turtles find their way and shields our air from the solar wind. Imagine it gone, compare Earth with Mars, and find out why scientists are calm about Earth's changing field.
• Watch Try it What If? Lab What if Earth had no Moon? The Moon's pull stretches Earth's oceans and gives us most of our tides. Take the Moon away in our tide model and see what is left: the Sun still makes tides, but they are less than half as big as the Moon's.
• Watch What If? Lab What if Earth had no mountains? Mountains push moving air upward so it drops rain and snow on one side, leaving the other side dry. Many rivers begin high in the mountains, and mountains are home to many plants and animals. Imagine flattening them all, and follow what might change.
• Watch What If? Lab What if Earth had no ozone layer? High above the clouds, a gas called ozone soaks up most of the Sun's harmful ultraviolet light before it reaches us. Chemicals made by people thinned it, so in 1987 countries agreed to phase them out. Imagine Earth with no ozone layer at all, and follow what might change.
• Watch What If? Lab What if Earth had rings? Saturn's rings are made of billions of chunks of ice and rock, all circling the planet. Earth has no rings today, but scientists have found clues that it may once have had one. Explore what rings are, where they come from, and what a ring might do to our sky.
• Watch Try it What If? Lab What if Earth had two moons? Our Moon goes round Earth in a neat, repeating loop. Add a second moon in our orbit model and watch what changes: the two moons tug on each other as well as on Earth, so their paths start to wobble.
• Watch What If? Lab What if Earth had two suns? More than half of the stars in the sky have a partner star. Astronomers have even found planets that go around two stars at once. Imagine Earth with two suns: you might see two shadows and two sunsets. Explore what scientists have really found.
• Watch Try it What If? Lab What if Earth had weaker gravity? When you throw a ball, gravity curves its path back down to the ground. Halve gravity in our model and the same throw climbs twice as high, stays up twice as long and lands twice as far away.
• Watch Try it What If? Lab What if Earth moved much faster around the Sun? Earth races around the Sun at about 30 kilometers every second, just the right speed for a nearly round path. Speed it up and its path stretches into a long oval. Speed it up to about 1.41 times as fast, around 42 kilometers per second, and the Sun's pull can no longer hold it: in our model, Earth flies off and never comes back.
• Watch Try it What If? Lab What if Earth rotated faster? One spin of Earth gives us one day and one night. Spin Earth twice as fast in our model and the days and nights each shrink to about six hours, with less time for the ground to warm up or cool down.
• Watch Try it What If? Lab What if Earth rotated slower? Slow Earth's spin to one turn a week in our model and a single afternoon lasts days. The ground has time to bake in the long sunshine and to chill in the long dark, so the gap between the hottest and coldest times grows far bigger.
• Watch Try it What If? Lab What if Earth slowed down in its orbit? A slower Earth does not just go round the same circle more slowly. In our model, starting Earth at 70 percent of its speed makes it fall inward on an oval that swoops closer to the Sun than Mercury's average distance, racing at over 64 kilometers per second at its closest, before swinging back out. Its year shrinks to about 197 days.
• Watch Try it What If? Lab What if Earth spun on its side like Uranus? Earth's spin axis leans 23.44 degrees, which gives us gentle seasons. Tip it all the way over to 90 degrees, like Uranus, and each pole points at the Sun in turn. In our model, a place 60 degrees north would get about four months of non-stop daylight, then about four months with no sunrise at all.
• Watch Try it What If? Lab What if Earth stopped rotating? You might think a world that does not spin would have no day and night. But Earth also travels around the Sun. Stop the spin in our model and the Sun still crosses the sky, just once a year: six months of daylight, then six months of night.
• Watch Try it What If? Lab What if Earth were covered in ice? White ice bounces sunlight back to space, so an icy planet soaks up less of the Sun's warmth. In our energy-balance model, making Earth reflect 60 percent of its sunlight instead of 30 percent drops its average temperature from about 15 °C to about −23 °C.
• Watch Try it What If? Lab What if Earth were farther from the Sun? Sunlight spreads out as it travels, so a planet farther from the Sun gets less of it. Move Earth out to where Mars orbits in our model, keep everything else the same, and its average temperature drops from about 15 °C to about −40 °C.
• Watch What If? Lab What if Earth were much bigger? Astronomers have found many planets bigger than Earth, called super-Earths. A simple calculation shows that an Earth twice as wide, made of the same rock, would pull twice as hard. Such a world might hold on to more air and might not grow such tall mountains.
• Watch What If? Lab What if Earth were the only planet? Imagine a solar system with just the Sun, Earth and our Moon. The bright 'wandering stars' would vanish from our night sky, the paths of asteroids and comets would change, and scientists would lose the other worlds that teach us how planets work. Explore what Earth would miss.
• Watch Try it What If? Lab What if Earth’s orbit were twice as wide? Move Earth's orbit out to twice its distance from the Sun and two things change at once: Earth has twice as far to travel, and the weaker pull lets it move only about 71 percent as fast. In our model, a year stretches from 365 days to about 1,033 days, almost three of our years.
• Watch Try it What If? Lab What if Earth’s tilt changed? Earth's axis leans 23.4 degrees, and that lean is what gives us seasons. Straighten Earth up in our sunlight model and the Sun climbs to the same height every noon, every day lasts 12 hours, and summer and winter disappear.
• Watch What If? Lab What if earthquakes could be predicted? No scientist has ever predicted a major earthquake, and USGS says nobody knows how. What scientists can do is work out the chances of a quake in an area, send a warning seconds after one starts, and help design buildings that shake less. Imagine we could know the exact day, and follow what might change.
• Watch What If? Lab What if electricity traveled without wires? A wireless charging pad sends energy across a tiny gap using a changing magnetic field, and scientists have even charged a car this way. But could electricity travel everywhere without wires? Follow three paths: charging pads, energy carried by radio waves, and why wires still carry our electricity across the country.
• Watch What If? Lab What if elephants stopped shaping the savanna? African elephants change the land around them. They feed on and push over trees, dig wells in dry riverbeds that other animals drink from, and carry seeds farther than almost any other land animal. Imagine elephants stopped doing all that: how might the savanna change?
• Watch Try it What If? Lab What if elephants talked with very low sounds? Elephants really do talk with very low rumbles, some too low for people to hear. Turn the pitch down in our sound model and see what changes about the wave, then find out how far real elephant calls can carry.
• Watch What If? Lab What if elevators did not exist? Elevators carry people up tall buildings in seconds. But before safe elevators, most buildings were only a few floors high. Imagine a world without them: shorter buildings, many more stairs and cities that spread out instead of up.
• Watch What If? Lab What if every animal slept at night? Night is busy. Barn owls hunt by sound in the dark, moths and bats take over the night shift of pollination, and fennec foxes leave their burrows once the hottest hours have passed. Imagine every animal sleeping at night: who would go hungry, who would overheat, and what jobs would be left undone?
• Watch What If? Lab What if every animal were the same size? The smallest bird weighs less than 2 grams; a big elephant weighs more than three million times as much. Size decides what an animal can eat, how it keeps warm and how fast its body runs. Imagine every animal squeezed or stretched to one size, and see what would go wrong.
• Watch What If? Lab What if every day had the same weather? Weather changes because the Sun heats some places more than others, and big bodies of warm or cold, wet or dry air keep moving around. Imagine a world where every day had the same weather: no need to check a forecast, but plants and animals that follow the seasons might be confused. Some places near the equator come surprisingly close.
• Watch What If? Lab What if every roof grew food? Most city roofs are bare, but some already grow lettuce, tomatoes and herbs, in boxes of soil or in water with no soil at all. Imagine every roof growing food. How would the plants get light and water up there? How much food could a city grow on top of itself? Explore what real rooftop farms have shown, and what they cost.
• Watch What If? Lab What if every snowflake were the same? Each snowflake grows as it falls through air that keeps changing in temperature and dampness, so no two take exactly the same path or end up exactly alike. Imagine a world where every snowflake were identical, and discover what that would take and what scientists would lose.
• Watch What If? Lab What if every surface were slippery? Friction is the grip between surfaces. It lets you walk, hold a pencil and stop a bike. Imagine a world where every surface was as slippery as ice, and follow what would happen to walking, writing and driving.
• Watch What If? Lab What if everyone had the same fingerprints? The swirls and loops on your fingertips form before you are born, and no two people's are known to match, not even identical twins'. That's why fingerprints are used to tell people apart and to unlock phones. Imagine a world where everyone's fingerprints were exactly the same, and discover how they form, what they might be for, and what would change.
• Watch What If? Lab What if everything were made of wood? Wood is strong, it grows on trees, and builders already frame most American homes with it. Today engineers even build towers from thick layered timber. Imagine a world where everything is wood, and find out what would work well, what would need care, and why.
• Watch What If? Lab What if fire had no oxygen? Every fire needs three things: fuel, heat and oxygen. Take away any one and the fire goes out. Follow what happens when the oxygen is taken away, from a candle under a jar in a science class to the way firefighters, fire extinguishers and smoke alarms keep people safe.
• Watch Try it What If? Lab What if fish had no swim bladder? Most bony fish carry a gas-filled pouch called a swim bladder. It makes the fish almost exactly as heavy for its size as the water around it, so it can stay at one depth without sinking or floating up. Use a floating-and-sinking model to see what happens when the gas is taken away.
• Watch What If? Lab What if fog never lifted? Fog is a cloud resting on the ground, made of tiny water droplets floating in the air. Most morning fog disappears as the Sun warms the ground. Imagine fog that never lifted: travel would be slower, but in some dry places people already use nets to catch drinking water from fog.