Shows / You'll Know Why
You'll Know Why
Why does your body do that? Why does the world work this way? You'll Know Why turns surprising questions about science, psychology, history, technology, money, and everyday life into short, clear stories you can understand in minutes — and repeat to someone else later. One question. One explanation. One thing you'll never look at the same way again.
Episodes
- You'll Know Why
The Gas in Your Kitchen Doesn't Smell Like Anything
That instantly recognizable smell is injected at a plant, in milligrams per cubic meter, long before the gas reaches your kitchen. The detector the whole…
- You'll Know Why
Your Sweat Doesn't Smell Like Anything
After a workout, everybody blames the same thing, and that thing is almost completely odorless. The molecules involved are too large and not volatile enough to…
- You'll Know Why
The Earth Is Closer to the Sun in Winter
Early January, northern hemisphere, the middle of winter, and about three million miles nearer the Sun than in July. Distance is clearly not what makes a…
- You'll Know Why
What Caffeine Actually Does
Caffeine doesn't make anything. Adenosine builds up in your brain over the hours you stay awake, settling into receptors that all carry the same message…
- You'll Know Why
Why a Golf Ball Is Covered in Holes
Golf balls leave the factory deliberately dented, three to five hundred craters apiece. A perfectly smooth one, hit exactly the same way, travels about half as…
- You'll Know Why
Your Wrinkled Fingers in the Bath Are Not an Accident
Only the ends go. Not your arm, not your back. The explanation everyone offers is that the skin drank up water and swelled, and the opposite is what happens…
- You'll Know Why
A Million and a Billion Sound the Same. They Aren't.
Turn them into time, which your body already understands. A million seconds is about eleven and a half days, and you can still remember what you were doing. A…
- You'll Know Why
Does Vitamin C Actually Protect You From a Cold?
Twenty-nine comparisons, more than eleven thousand participants taking it daily, and in the general population no reduction in the number of colds caught. How…
- You'll Know Why
Why Your Screen Goes Black Through Sunglasses
Tilt your head and the display goes completely black. Nothing is broken, and nothing is reflecting. Your polarized lenses pass light vibrating in one direction…
- You'll Know Why
No Blue Bird Is Actually Blue
Kingfisher, blue jay, peacock: there is no blue pigment in any of those feathers. The color lives in a keratin foam riddled with air pockets about the size of…
- You'll Know Why
Why Beans Make You Fart
Not fiber, and not beans simply being hard to digest. They carry three sugars your small intestine cannot break down, because it makes none of the enzyme…
- You'll Know Why
Why You Can't See Clearly Underwater
Blame usually lands on the chlorine, or on the water not being clear enough. The trouble is in your eye, in the part nobody thinks about. Two-thirds of its…
- You'll Know Why
Why Growers Coat Fruit Blossom in Ice to Save It From Frost
An April night, the trees in blossom, the temperature dropping toward twenty-eight. The grower goes out, turns on the irrigation and leaves it running until…
- You'll Know Why
You Can Be Given a Memory of Something That Never Happened
Three real childhood memories supplied by a relative, and a fourth invented from nothing. About a quarter of participants were classified as having developed a…
- You'll Know Why
How a Traffic Light Knows Your Car Is There
Look at the asphalt just before the stop line and you will often see a big rectangle traced in thin, filled-in grooves. Most people assume it is a repair…
- You'll Know Why
Why Alcohol Makes You Feel Warm and Puts You in Danger
The warmth is real, and it is heat on its way out. Your temperature sensors sit in your skin, reporting honestly on what they measure, which is warm blood…
- You'll Know Why
Why Gold, and Not Some Other Metal
Walk the periodic table with one requirement, something to store value in, and rule out the gases, anything that rusts or burns, anything radioactive, anything…
- You'll Know Why
Why Asparagus Changes the Smell of Your Pee
Half the table has no idea what you are talking about. The usual explanation puts the difference in who produces the smell. The best-documented difference is…
- You'll Know Why
Not Digesting Milk Is the Normal Setting
Worldwide, adults who don't digest milk are the large majority. Almost every mammal shuts that enzyme down after weaning, and we are no exception. What…
- You'll Know Why
What Zebra Stripes Are Actually For
Zebras and ordinary horses in the same paddock, with a camera trained on the horseflies. From a distance the flies arrive just as often on both. It is at the…
- You'll Know Why
Why There's a Grid on Your Microwave Door
Between you and your plate sits a perforated metal sheet, and that sheet is the wall keeping the microwaves in. Not the glass. A wave about five inches long…
- You'll Know Why
There Are No Muscles in Your Fingers
Put a hand on your forearm and wiggle your fingers. What moves is a long way from what you are moving. A finger holds bone, skin, vessels, nerves and tendon…
- You'll Know Why
Nobody Sees the Same Rainbow You Do
It isn't an object and it isn't at any distance. It's an angle, about forty-two degrees out from the shadow of your own head. The person standing three feet…
- You'll Know Why
Why AMBULANCE Is Written Backwards
A mirror is going to flip the word anyway, so somebody flipped it first and let the two reversals cancel out. The driver ahead reads it in the one second where…
- You'll Know Why
Why Clock Hands Turn the Way They Do
Nobody voted on this. The direction comes from a stick pushed into the ground, and the shadow it threw across the northern hemisphere for centuries before any…
- You'll Know Why
Why Manhole Covers Are Round
A square cover, turned and tipped on its diagonal, drops straight into its own hole, because that diagonal runs about forty percent longer than a side. A…
- You'll Know Why
Do Carrots Really Help You See in the Dark?
Wartime Britain really did run the campaign: posters, a cartoon character, slogans. A night-fighter ace really was running up victories, thanks to airborne…
- You'll Know Why
Why a Bottle of Water Freezes the Instant You Set It Down
Hours in the freezer and it is still liquid, well below freezing, waiting. Ice needs a starting point to organize itself around, and very pure, very still…
- You'll Know Why
Should You Put a Fallen Baby Bird Back in the Nest?
Touching it will not make the mother abandon her chick, because that isn't how she recognizes it. But the conclusion isn't the permission you were expecting…
- You'll Know Why
How Much Would a Spoonful of a Neutron Star Weigh?
A centimeter cube of it would weigh on the order of a billion tons. The star it came from is about a dozen miles across and carries roughly the mass of the…
- You'll Know Why
Spicy Isn't a Taste
Your taste buds never detect it. The receptor a chili opens is the one that reports dangerous heat, at around a hundred and ten degrees. The pepper brings no…
- You'll Know Why
What "Forty Percent Chance of Rain" Actually Means
Not that it rains for forty percent of the day, and not that it rains on forty percent of the city. The National Weather Service definition is narrower than…
- You'll Know Why
Why the Same Wine Tastes Better When It Costs More
Same wine, two announced prices, volunteers lying inside a brain scanner. With the high price they reported more pleasure, and the pleasure-linked region…
- You'll Know Why
Why Reading in a Car Makes You Sick
Your inner ear reports every turn and every bump in the road. Your eyes, locked on a screen a foot away, report that nothing is moving. That disagreement…
- You'll Know Why
Where Does the Wax Go When a Candle Burns?
No puddle in the morning, and nothing ever disappears. The wick isn't the fuel; it's a pump. What actually burns is a gas, and what leaves the top weighs more…
- You'll Know Why
Do Rats Laugh When You Tickle Them?
Too high-pitched for a human ear, so the Berlin team brought an ultrasound microphone. The rats answer a tickled belly with a downpour of calls, then chase the…
- You'll Know Why
Does Sugar Really Make Kids Hyper?
Twenty-three double-blind trials, fourteen different measures, and no effect on the children's behavior. So what are the parents seeing? Another experiment…
- You'll Know Why
What Would Really Happen If You Fell Into a Black Hole
Everything depends on its size. Fall into a small one and the pull on your feet outruns the pull on your head so violently that astrophysicists have an…
- You'll Know Why
The Floating Egg Test: What It Actually Tells You
The glass of water works. It just answers a question you weren't asking. A shell is punched through with thousands of pores, so the air pocket inside grows as…
- You'll Know Why
Do Identical Twins Have the Same Fingerprints?
They start from the same fertilized egg, and their prints still don't match. Genes set the general pattern. The fine detail is decided between the tenth and…
- You'll Know Why
Why a Bird on a Power Line Doesn't Get Electrocuted
Both feet sit on the same wire at almost the same electrical level, and the gap between them is far too small to push anything dangerous through. Change one…
- You'll Know Why
Does the Red in Your Yogurt Really Come From an Insect?
Turn the cup over and look for three names. If one of them is printed there, the red came from insects harvested off cactus in South America. It holds its…
- You'll Know Why
How Much Does a Cloud Weigh?
A fair-weather cumulus weighs about a million pounds, roughly a hundred elephants overhead, and nothing falls. The calculation is short enough to follow…
- You'll Know Why
Why Your Veins Look Blue When Your Blood Is Red
Blood leaving your lungs is bright red, and blood coming back is dark like wine. Never blue. The lines under your skin are not a color your body contains; they…
- You'll Know Why
What's Actually Inside a Dromedary's Hump
Fat, not water. Which makes the real question a better one: how does it go days without drinking? Part of the answer is oval red blood cells that soak up…
- You'll Know Why
Thirty Kids in a Class. Do Two Share a Birthday?
Three hundred and sixty-five days, thirty kids, and the odds of a shared birthday are better than seven in ten. Your gut gets this wrong for one specific…
- You'll Know Why
The Taste Map of the Tongue Is Wrong
Sweet at the front, bitter at the back: you may have copied that diagram in class. Put something sweet on the side of your tongue and it tastes sweet. The…
- You'll Know Why
Which Way Does the Water in Your Sink Actually Spin?
Drain your sink twice and you won't get the same direction twice. The force everybody credits is real, and in a basin it is millions of times weaker than…
- You'll Know Why
Does Cracking Your Knuckles Really Wreck Your Joints?
One doctor cracked the knuckles of a single hand at least twice a day for fifty years and kept the other hand as a control. No arthritis on either one. The…
- You'll Know Why
Your Dog Is One. How Old Is He Really?
Multiply by seven and a one-year-old dog is a second grader, except a one-year-old dog can already have puppies. Researchers read the DNA of a hundred and four…
- You'll Know Why
How Surgeons Operate on a Brain While the Patient Plays Guitar
The patient is awake, talking, counting, playing, while a surgeon works inside their head. Brain tissue sends no pain signal of its own, which is what makes…
- You'll Know Why
Left Brain, Right Brain: What the Scans Found
More than a thousand brains scanned at rest, more than seven thousand regions in each, and one question: does anybody use one side more overall? They found…
- You'll Know Why
Why You Can't Stand Your Own Recorded Voice
Play back a voice message and something in you flinches. That stranger is the version everyone else has always heard. The one you trust arrives through the…
- You'll Know Why
Why the Moon Seems to Follow Your Car
Trees, houses and telephone poles all sweep past your window. The Moon doesn't budge, so your brain reaches the only conclusion it can: it must be traveling…