Science
Why ice floats, why mirrors seem to flip left and right: the small laws behind everyday things.
32 articles
When was zero discovered?
Zero, the number for nothing at all, seems utterly obvious. Yet it took humanity a very long time to get hold of it.
Is an atom mostly empty space?
Desks, air and our own bodies are all made of atoms. Peer inside an atom, though, and you find a landscape nothing like what you might imagine.
Why do magnets stick to things?
A magnet clings to the fridge door yet ignores aluminum cans and copper coins. How does a magnet choose what it sticks to?
How do fireworks get their colors?
Great bursts of red, green and blue across the night sky. Those vivid colors are not painted on. And the fireworks people watched in old Edo looked completely different.
Does air have weight?
You can’t see air or hold it in your hand. But if you gathered up all the air in the room you’re sitting in and put it on a scale, how far would the needle swing?
What makes the fizz in a carbonated drink?
The hiss when you crack the cap, the fine bubbles streaming up from the bottom of the glass. Where exactly are those bubbles born?
Why does road salt melt ice?
On snowy mornings, roads and bridges are often scattered with white grains. Why does salt make ice melt? And why does it work worse the colder it gets?
Why do we see lightning before we hear thunder?
A flash, then a pause, then the rumble. Lightning and thunder are born in the same instant, so why do they reach us at different times? That gap has also served science remarkably well.
What happens if you light a candle in space?
A candle flame always points upward. So what shape would it take in space, where there is no up or down? Astronauts have actually tried it.
Why do soap bubbles shimmer with rainbow colors?
Soapy water itself is almost perfectly clear. Yet the moment you blow a bubble, swirling patterns of color start dancing across its surface.
How many elements are there?
Water, air and our own bodies are all made of combinations of elements. So how many elements are there in total? The latest count includes one that was born in Japan.
Is glass a liquid?
“Old church windows in Europe are thicker at the bottom, because glass is a slow-flowing liquid.” You’ve probably heard it. But is it true?
What is the white fog from dry ice?
Drop the dry ice from a cake box into water and white smoke comes billowing out. It certainly looks like a cloud of carbon dioxide. But is it?
What is the hardest material in the world?
Scratch it, press it, hit it: “hard” can be measured in many ways. The race for the world title turns out to be surprisingly tangled.
Do mirrors really reverse left and right?
Raise your right hand in front of a mirror, and the person in the glass seems to raise their left. So why doesn’t a mirror flip you upside down?
How does a microwave oven heat food?
No flame, no hot plate, yet your food is steaming in minutes. What on earth is going on inside that box?
How does a steel ship float?
Drop an iron nail into water and it sinks at once, yet ships built from tens of thousands of tons of steel float. The difference comes down not to the metal, but to its shape.
Why does metal feel colder than wood?
On a winter morning, playground bars feel icy but the wooden bench doesn’t. Yet a thermometer says they’re the same temperature. So what is your hand feeling?
Did Archimedes really shout “Eureka”?
A genius makes a great discovery in the bath and runs into the street naked. The most famous story in the history of science comes with more than a few question marks.
Why does ice float on water?
Most substances sink in their own liquid once they solidify. Yet the ice in your glass bobs happily at the top. What makes water so different?
Why does static electricity give you a shock?
In winter, touching a doorknob or a car door becomes a little nerve-racking. That sudden sting is a tiny lightning bolt driven by thousands of volts.
Why is ice slippery?
Almost everyone has lost their footing on an icy path. Yet the reason behind something so familiar is a puzzle physicists have argued over for more than 170 years.
Is pencil lead made of lead?
We call it “lead,” and the Japanese word for pencil contains the character for lead. But trace that black core back and you reach 16th-century English shepherds.
Why does water boil at a lower temperature on a mountain?
Water boils at 100°C—or so we learned in school. That rule doesn’t hold everywhere. High on a mountain, a pot of water behaves very differently.
How many times can you fold a piece of paper?
“No matter how hard you try, you can’t fold paper more than eight times.” The person who took on that old saying was a high school student given a math assignment.
Can water stay liquid below 0°C?
Tap a bottle of water fresh from the freezer, and it turns to slush before your eyes. Behind this magic trick lies a surprising property of water.
Why does an ambulance siren change pitch as it passes?
A siren sounds high as it approaches and drops the moment it passes. To test this effect, a 19th-century Dutch scientist put musicians on a train.
How do batteries make electricity?
The little batteries in our remote controls and clocks are packed with a discovery that began more than 200 years ago, with a twitching frog’s leg.
Why does the Moon look bigger near the horizon?
A full Moon just rising over the hills can look astonishingly large. Yet in a photo, it somehow shrinks. It’s a puzzle that has baffled people for more than 2,000 years.
How many digits of pi have been calculated?
3.14159… and on forever. For more than 2,000 years, people have chased the next digits of pi. How far has the record gone?
Is there an upper limit to temperature?
Cold has a floor, a point below which nothing can go. But what about heat? The hottest thing humans have made was over 300,000 times hotter than the Sun’s core.
Is it true that pure water doesn’t conduct electricity?
We’re taught never to touch an outlet with wet hands, yet we also hear that pure water doesn’t conduct electricity. So which is it?