Every discovery, with its sources.

Nº 068 · Numbers · 50 sec

Switch or stay? The door puzzle that had mathematicians arguing

Three doors, one car, two goats – and a correct answer that drew some 10,000 letters in 1990.

Nº 067 · Body · 50 sec

Gut-lining cells live for days, the neurons in your cortex for a lifetime

There is no brand-new body every seven years. Ironically, carbon from atomic bomb tests gave the game away.

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Nº 066 · Nature · 50 sec

A brainless slime mould designed a network like Tokyo's railways

Oat flakes were laid out like the cities around Tokyo. After about a day, a yellow single cell had linked them – much like the real rail network.

Nº 065 · Nature

Bacteria conduct electricity in the seafloor.

Cable bacteria transport electrons through long threads. Conducting fibres inside contain nickel proteins.

Nº 064 · Technology · 50 sec

The kilogram prototype got lighter – or all its copies got heavier

For 130 years, a metal cylinder near Paris was by definition exactly one kilogram. That was precisely the problem.

Nº 063 · Numbers · 50 sec

Why do so many numbers start with a 1?

In real-world data, a 1 comes first more than six times as often as a 9. Tax investigators use that.

Nº 062 · Numbers · 50 sec

A sheet of paper all the way to the Moon?

A sheet is 0.1 mm thick, the Moon about 384,400 km away. The answer sounds like a miscalculation.

Nº 061 · Numbers · 50 sec

How many people does it take to share a birthday?

A year has 365 days. Even so, the answer is far smaller than almost anyone guesses.

Nº 060 · Technology

The fax is older than the telephone.

Alexander Bain patented the principle in 1843 – 33 years before Bell's telephone. It wasn't ready for everyday use.

Nº 059 · Nature

The lemming plunge in the film was staged.

For Disney's 1958 film, animals were pushed off a cliff. The mass-suicide myth is false.

Nº 058 · History · 50 sec

Krakatoa's blast could still be heard 4,800 kilometers away

On an island in the Indian Ocean in 1883, people took it for cannon fire. Barometers around the world recorded the pressure wave for days.

Nº 057 · History · 50 sec

How could a wave of molasses kill 21 people?

Boston, January 1919: a tank holding 8,700 cubic meters of molasses bursts. What happens next doesn't fit the image of sluggish syrup.

Nº 056 · History · 50 sec

What does a volcanic eruption have to do with Frankenstein?

In 1815, Tambora explodes in Indonesia. A year later, an 18-year-old is stuck in endless rain on Lake Geneva – and invents a monster.

Nº 055 · Physics · 50 sec

Around 2 billion years ago, a nuclear reactor ran in Gabon – on its own

In 1972, uranium from Africa came up short on its fissile isotope. Nobody had stolen it – nature had burned it up itself.

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Nº 054 · Space

Neutrinos pass through your thumbnail.

About 65 billion per second, from the Sun. They pass through matter almost unimpeded – you feel nothing.

Nº 053 · Physics · 1 min

Ice skates don't melt the ice. So why is it slippery?

For a long time the answer was: the blade's pressure melts the ice. The numbers don't add up. What happens instead is still debated by physicists.

✦ New research Nº 052 · Nature

Glass frogs hide their red blood cells.

At rest they store almost 90 percent of their red blood cells in their liver, becoming more transparent.

✦ New research Nº 051 · History · 55 sec

The oldest dated cave art is a hand – at least 67,800 years old

A faded patch of paint on an island off Sulawesi beats the previous record. It was dated with a clock that ticks inside crusts of calcite.

✦ New research Nº 050 · Nature

Ants have farmed fungi for millions of years.

They started about 66 million years ago. Dated family trees of fungi and ants reveal when it began.

✦ New research Nº 049 · Physics · 55 sec

Antimatter falls down. Nobody measured it until 2023

Theory predicted it, but no one had seen it. At CERN, a team first directly observed anti-atoms falling – and where they landed.

✦ New research Nº 048 · Perception · 55 sec

Five people have seen a color that doesn't exist in nature

A laser at Berkeley stimulated just one type of cone cell. The result was "olo": a blue-green more saturated than any color in nature.

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✦ New research Nº 047 · Nature

Jellyfish learn without a central brain.

After a few collisions, they kept further away from obstacles. Learning happens in their sensory clubs.

✦ New research Nº 046 · Nature

Painted ladies can cross the Atlantic.

Researchers found them in French Guiana carrying pollen from the Sahel. Trade winds carried them across the ocean.

✦ New research Nº 045 · Nature

Genetically, a starfish is almost all head.

Head genes are active almost everywhere, trunk genes hardly. Researchers mapped them in starfish arms.

✦ New research Nº 044 · Nature · 50 sec

Bogong moths find their way by the stars

They fly up to 1,000 kilometres to caves they have never seen. A flight simulator with an artificial night sky shows what guides them.

✦ New research Nº 043 · Nature

Mice pull the tongues of unconscious partners.

In an experiment, mice groomed familiar cagemates and removed objects from their mouths. The unconscious mice woke sooner.

✦ New research Nº 042 · Nature

An orangutan treats his wound.

Rakus chewed leaves, dabbed their juice onto a facial wound and covered it with the pulp.

✦ New research Nº 041 · Nature · 50 sec

Do elephants call each other by name?

Researchers had software analyse elephant calls – then played the animals what seemed to be their own names.

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Nº 040 · Technology · 50 sec

The first computer bug was a real moth

Taped into the logbook. Only the word "bug" was already old by then.

Nº 039 · Nature · 50 sec

Why does the zebra have stripes?

Camouflage? Cooling? An experiment with striped horse blankets gives a surprising answer.

Nº 038 · Body · 50 sec

Do you taste sweet only with the tip of your tongue?

The famous tongue map with zones for sweet, sour, salty and bitter is a misunderstanding.

Nº 037 · Space · 50 sec

A planet found with pen and paper

Before anyone knowingly saw it, Neptune had already been calculated.

Nº 036 · Technology

QR codes were invented for car parts.

Denso Wave developed them in 1994 to label vehicle parts. The code could be read faster than a barcode.

Nº 035 · Body

Babies have more bones than adults.

Some bones fuse as we grow. About 270 bones at birth become roughly 206 in adulthood.

Nº 034 · Space

Saturn would float in water.

Its average density is lower than water's. A suitable bathtub would have to be enormous.

Nº 033 · Physics

Lightning is hotter than the Sun's surface.

Air in a lightning channel can reach about 27,800 degrees Celsius. Its rapid expansion produces thunder.

Nº 032 · History

Vikings didn't wear horned helmets.

The horned image became popular through Wagner's operas in the 19th century. Real Viking helmets are extremely rare.

Nº 031 · Nature

Hummingbirds can fly backwards.

Their wings allow flight in any direction – including backwards and hovering on the spot.

Nº 030 · Nature

Male seahorses get pregnant.

The female deposits eggs in his brood pouch. Later, the male releases fully developed young.

Nº 029 · Nature

Greenland sharks can live for over 270 years.

They are the longest-lived vertebrates known. Their age is determined from the lenses of their eyes.

Nº 028 · Nature

Octopuses have nerve cells in their arms.

Two-thirds of their nerve cells are in their arms. In total, an octopus has over 500 million.

Nº 027 · Physics

Bananas are slightly radioactive.

Natural potassium-40 makes them slightly radioactive. Your body excretes excess potassium.

Nº 026 · Space

A sugar cube as heavy as a mountain.

Made of neutron-star matter, a tiny piece would have a mass of about a billion tons on Earth.

Nº 025 · History

Oxford is older than the Aztec Empire.

Teaching took place in Oxford around 1096; the Aztec Empire only arose in 1428.

Nº 024 · Nature

Flamingos eat their way to pink.

Their colour comes from their food. Young flamingos hatch greyish and turn pink later.

Nº 023 · Nature

Peanuts aren't nuts.

Botanically they are legumes, related to peas and beans. Their pods ripen underground.

Nº 022 · History

The Great Wall is invisible from the Moon.

At that distance it is too narrow to see – like a human hair viewed from three kilometres away.

Nº 021 · Nature

Tardigrades survived the vacuum of space.

Ten days without air: back on Earth, water was enough to revive the tiny animals.

Nº 020 · Nature

A shrimp makes light with its claw.

Its claw creates a bubble that collapses with a bang and a brief flash of light.

Nº 019 · History

Scotland's national animal: a unicorn.

On the British coat of arms, the unicorn represents Scotland and the lion represents England.

Nº 018 · History · 40 sec

Cleopatra lived closer to the Moon landing than to the building of the pyramid

To us it's all "ancient Egypt". To Cleopatra, the Great Pyramid was already ancient.

Nº 017 · Physics · 45 sec

Does old window glass flow downward?

Old panes are often thicker at the bottom. The explanation sounds plausible – and is wrong.

Nº 016 · Physics · 1 min

Does time pass faster on a mountain?

Yes. Measurably so even a few stair steps higher – and your phone accounts for it every day.

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Nº 015 · Physics · 1 min

A glass of water against all the oceans

Are there more water molecules in a glass than glasses of water in the seas? Let's do the math.

Nº 014 · Physics · 1 min

How heavy is a cloud?

It floats above you. How much water does a cumulus cloud of one cubic kilometre hold?

Nº 013 · Physics · 55 sec

Why does metal feel colder than wood?

Even though both are exactly the same temperature. Your skin doesn't measure temperature at all.

Nº 012 · Perception · 1 min

There's a hole in your field of view.

Every eye has a blind spot. You've never noticed yours – your brain simply paints it over.

Nº 011 · Perception · 1 min

Can you trust your eyes?

Two orange circles. One looks bigger. See how strongly your brain fools you.

Nº 010 · Nature · 45 sec

Why is a banana a berry but a strawberry isn't?

In botany, the name doesn't count – how the fruit forms from the flower does.

Nº 009 · Nature · 50 sec

Were there sharks before trees?

Their ancestors, yes. Today's sharks, on the other hand, are younger than the first forests.

Nº 008 · Nature · 55 sec

Why is a mushroom more closely related to you than to a plant?

It sits in the forest floor and doesn't move. Yet it belongs on our side of the family tree.

Nº 007 · Nature · 45 sec

Why does the wombat make cube-shaped poop?

A round gut shapes cubes. Researchers only recently worked out how.

Nº 006 · Nature · 50 sec

12 color receptors – and still bad at seeing colors?

It has one of the most complex eyes in the animal kingdom. And tells colors apart worse than we do.

Nº 005 · Nature · 45 sec

One animal. Three hearts.

Two pump blood through the gills, one through the body – and that one takes a break when it swims.

Nº 004 · Space · 1 min

Why is Earth closest to the Sun in January?

In the middle of winter. Distance doesn't make the seasons – something else does.

Nº 003 · Space · 50 sec

How old is the sunlight on your skin?

Eight minutes – and many thousands of years.

Nº 002 · Space · 50 sec

Why is a day on Venus longer than its year?

It spins so slowly that it circles the Sun faster than it turns once.

Nº 001 · Space · 1 min

Why do we always see the same side of the Moon?

It does spin – exactly once per trip around Earth.

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