Tag
Pushes & pulls
Gravity, friction, and things that will not stay still — 164 tiny stories across 9 shelves.
Physics
Invisible forces you can play with — 37 stories.
All physics →An invisible ocean
Air Is Pressing on You
Ten tonnes of air is pressing on you right now and you feel nothing, because it presses equally from every side. Break that balance and you notice.
Let’s go →A hidden middle
What Keeps Things From Falling Over?
Every object has a balance point. It stays upright only while that point sits over its base, which is why a wide base and low weight rarely tip.
Let’s go →Pressure from below
Why Does Water Push Up?
Water pressure is stronger the deeper you go, so the push on an object's underside beats the push on its top. That leftover push is what holds it up.
Let’s go →Climbing without a pump
Why Does Water Climb Up a Paper Towel?
Look at the curved edge where water meets a glass. A paper towel is that same edge repeated through countless tiny channels, all pulling at once.
Let’s go →Passing motion along
What Happens When Things Crash?
Motion is never destroyed in a crash, only handed over. What decides the damage is not the speed itself but how long the stop is allowed to take.
Let’s go →Heavy for its size
What Is Density?
Density is not weight but how much weight is packed into a given space. It is what decides whether a thing floats, sinks, or rises through the air.
Let’s go →It never goes anywhere
Where Does Energy Go When Things Stop?
Energy is never used up when something stops. It has only changed form, and every change spills a little as heat that is hard to use again.
Let’s go →Water pushes back
Why Do Things Float?
You float when the water you shove aside weighs more than you do. That is why a steel hull floats where a solid steel lump sinks straight to the bottom.
Let’s go →Why things stop
What Is Friction?
Every surface is rough close up. Friction is those roughnesses catching and grinding on each other, quietly turning motion into heat as they go.
Let’s go →Trading speed for strength
How Do Gears Work?
Count the teeth and you have the ratio. Ten driving thirty means three turns for one, and three times slower is three times the turning force.
Let’s go →The pull you never notice
What Is Gravity?
Every object with mass pulls on every other one. Earth simply has enough mass for its pull to dominate everything you have ever felt.
Let’s go →Cavendish, 1798
How Anyone Weighed the Earth
Henry Cavendish weighed the Earth by measuring the faint pull between four lead balls, in a sealed shed he watched through a telescope from outside.
Let’s go →Water breaks the rules
Why Does Ice Float?
Almost everything shrinks as it freezes. Water does the opposite, locking into an open, gappy lattice that takes up more room — so the solid floats.
Let’s go →The answer is: nothing
What If Everyone Jumped at Once?
If everyone on Earth jumped together, the planet would shift by less than the width of an atom — and then shift straight back.
Let’s go →You would not get stronger
What If Gravity Were Half as Strong?
Your jump would double and nothing about you would improve: bones weaken, trees overreach, and the planet slowly leaks its air away.
Let’s go →You would come back
What If You Fell Through a Hole in the Earth?
A hole through the Earth is a pendulum. You speed up to the centre, slow down to the far side, and it takes 42 minutes each way.
Let’s go →You could not start, either
What If Friction Stopped for One Minute?
Everyone expects to slide. Almost nobody expects to be unable to start, hold, stand, or keep a single screw or knot from letting go.
Let’s go →Nothing changes for free
Why Do Things Keep Moving?
An object keeps doing exactly what it was doing until something makes it stop. Every change of speed or direction has to be paid for with a force.
Let’s go →Trading distance for force
How Do Levers Work?
A lever lets a small push move a big load, by making you push a long way to shift it a short one. Force and distance always trade off against each other.
Let’s go →Invisible reach
How Do Magnets Work?
Iron is already full of tiny atomic magnets, and magnetising it only lines them up. That is why cutting a magnet in half gives you two whole magnets.
Let’s go →Our planet is a magnet
Why Does a Compass Point North?
Molten iron churning deep inside the planet generates a magnetic field reaching out into space. A compass needle is just a small magnet lining up with it.
Let’s go →Mass times speed
Why Are Heavy Things Hard to Stop?
Nothing is lost when things collide: what one object loses another gains. Airbags, crash mats and bent knees simply make the stop take longer.
Let’s go →Not the chair, not this page
You Have Never Touched Anything
Solid contact is a force, not a meeting — the outer electrons of two surfaces repel each other hard enough that nothing ever quite arrives.
Let’s go →Air shoved out of the way
How Does a Parachute Slow You Down?
A parachute does not slow you by being large. It forces you to shove a huge amount of air aside, and the air pushes back until it balances your weight.
Let’s go →A reliable swing
Why Does a Pendulum Keep Time?
A pendulum's swing takes the same time whether it swings wide or narrow, because the period depends on the string's length and nothing else.
Let’s go →Force, spread out
What Is Pressure?
The same push feels utterly different depending on the area it lands on. Shrink the area and you have a drawing pin; spread it out and you have a snowshoe.
Let’s go →Sharing the load
How Do Pulleys Help?
Run the rope through more pulleys and the load is shared across more sections, so each pull is lighter. You pay for it by pulling a great deal more rope.
Let’s go →Newton's third law
Every Push Has a Push Back
You cannot push anything without it pushing back exactly as hard. That pair of forces is what makes walking, swimming and flying possible at all.
Let’s go →The same climb, stretched out
Why Are Ramps Easier?
A ramp does not reduce the work of getting up there. It spreads the same climb over a longer walk, trading a hard short lift for an easy long push.
Let’s go →A thin film of water
Why Is Ice So Slippery?
Ice carries a film of liquid water well below freezing, because its top layer of molecules has nothing above to hold it in place. That film is the slip.
Let’s go →Nothing is pushing it out
Why Does the Water Stay in the Bucket?
Nothing flings the water outward. It never turns at all — the bucket keeps curving into its straight path and shoving it inward, over and over.
Let’s go →Storing a push
How Do Springs Work?
A spring stores the work you put into squashing or stretching it, then hands that energy straight back as it returns to its own shape.
Let’s go →Rubbed the wrong way
Why Do You Get Shocks?
Rubbing moves electrons by the billion, and they sit on you until the pile-up can rip air apart to escape. A door handle can hit 3,000 volts harmlessly.
Let’s go →A skin made of pulling
Why Does a Paperclip Float on Water?
Water molecules cling to one another so strongly that the surface behaves like a stretched skin, and a paperclip simply rests in the dent.
Let’s go →Empty space cannot push
What Does Nothing Actually Do?
Air strikes every square centimetre of you with about a kilogram of force, from all sides at once — which is why a can crumples and you do not.
Let’s go →Wobbling back to the middle
Why Do Things Vibrate?
Push something springy out of shape and it overshoots the middle coming back, then overshoots again. Match its natural rate and the swing keeps growing.
Let’s go →Rolling beats dragging
Why Are Wheels So Good?
A wheel does not slide against the ground. Its contact patch sets down and lifts off again, which replaces sliding friction with very nearly none.
Let’s go →How things work
Everyday machines, taken apart — 33 stories.
All how things work →Throwing air downwards
Why Does a Wing Hold a Plane Up?
A wing throws air downward and the air shoves back. Lift grows with the square of speed, so twice as fast is four times as much of it.
Let’s go →Lighter than air, and too slow
Why Did Airships Stop Flying?
Airships float because their gas is lighter than air, but they were too slow and too big for weather, and aeroplanes overtook them.
Let’s go →Constant, invisible steering
Why Does a Moving Bike Stay Up?
The forks are angled so the front wheel trails behind the steering axis and turns into a fall by itself, curving the bike back upright.
Let’s go →Turning speed into heat
How Does Rubbing Stop a Car?
Brakes do not remove a car's energy, they convert it. Pads squeeze a spinning disc and all that movement leaves as heat the disc sheds into the air.
Let’s go →Two shapes that do not fold
Why Do Bridges Have Arches and Triangles?
Bridges use arches, triangles and cables because those shapes turn bending, which materials are bad at, into pushing or pulling, which they handle well.
Let’s go →Raise the water, not the boat
How Does a Boat Go Uphill?
A lock does not lift a boat. It seals the boat into a chamber and changes the water level, so the boat simply keeps floating at a new height.
Let’s go →Three feet always land
Why Does a Chair Wobble When a Stool Never Does?
Any three feet reach the floor together, because three points settle a flat surface between them. A fourth has to match a surface decided without it.
Let’s go →A see-saw with a concrete end
Why Doesn't a Crane Tip Over?
A tower crane is a see-saw about its mast: a block of concrete on the short arm balances whatever hangs from the long one, distance included.
Let’s go →Oil that refuses to be squashed
How Does a Digger Lift So Much?
Oil cannot be squashed, so pressure from a small piston reaches a much larger one, which pushes proportionally harder. That is the whole arm.
Let’s go →Only lifting the difference
Why Does a Lift Need a Counterweight?
A counterweight balances almost all of the car, so the motor only ever lifts the difference between the two — a small fraction of the whole load.
Let’s go →Stopping the cabin spinning
Why Does the Little Tail Rotor Matter?
Spinning the main blades twists the body the other way, so a small rotor on the tail pushes sideways to cancel the twist and hold the nose still.
Let’s go →Buying time, by millimetres
How Does a Helmet Protect a Head?
A helmet does not make your head harder. It crushes, which stretches a sudden stop over more time and cuts the force a brain must survive.
Let’s go →Rope gripping rope
Why Does a Knot Hold?
Nothing in a knot is glued or clipped. Pulling the rope squeezes its own crossings together, and rope pressed on rope refuses to slide.
Let’s go →Steel on steel, barely gripping
How Can One Engine Pull a Two-Kilometre Train?
Steel wheels on steel rails barely rub, so one engine can pull an enormous train — and barely grip, so it cannot stop quickly.
Let’s go →Sheets that slide off
Why Does a Pencil Leave a Mark?
The name comes from a 16th-century find people mistook for lead. More clay in the mix means fewer sheets come away, which is what makes a line fainter.
Let’s go →A wing going round in circles
How Does a Propeller Pull a Plane?
A propeller blade is a wing bent into a circle. Instead of lifting upward it lifts forward, throwing air backward and never once stopping.
Let’s go →Two pushes and a leftover
How Does a Boat Sail Into the Wind?
A sail turns wind into a mostly sideways push, the keel refuses to go sideways, and what is left over carries the boat forward, even upwind.
Let’s go →Two levers and a travelling point
Why Do Scissors Cut When One Blade Cannot?
One blade alone cannot cut, but two levers squeezing from opposite sides can — at a single point of contact that travels from pivot to tips.
Let’s go →One foot always down
Why Is a Scooter Easier Than a Bike?
A scooter is easier than a bicycle because you stand low with a foot free, so a wobble is corrected instead of becoming a fall.
Let’s go →A ramp wrapped round a stick
Why Is a Screw So Hard to Pull Out?
A screw is a ramp rolled into a spiral, turning many easy rotations into one enormous squeeze. Pulling it straight out fights the whole spiral at once.
Let’s go →It falls there, mostly
How Does Water Climb to the Tap?
Water reaches your tap because it is stored higher than your house, and that height alone is what supplies the pressure inside the pipes.
Let’s go →A siphon, not a plug
Why Does a Toilet Flush by Itself?
A toilet flushes because a sudden rush of water fills the bend behind the bowl, and a full bend pulls the rest away by itself.
Let’s go →Grip, not speed
Why Do Tractors Have Huge Back Wheels?
A tractor is built to pull, not to travel: huge rear wheels give the grip that pulling needs and spread the weight so it does not sink.
Let’s go →Cones, not lips
Why Do Train Wheels Never Fall Off?
The inner lip hardly ever touches the rail. Leaning outward in a bend puts the outer wheel on a wider diameter, so it covers the extra distance itself.
Let’s go →Spreading the load
Why Do Trucks Have So Many Wheels?
Road damage depends on what each wheel presses down, not on the total, so a truck spreads thirty cars' worth of weight across many axles.
Let’s go →Not stronger. Just patient
How Does a Tiny Tugboat Move a Huge Ship?
A tug cannot outmuscle a container ship and does not have to: floating removes the weight, so a small push held for minutes moves anything.
Let’s go →Hold the roof up before you make it
How Do You Dig a Tunnel Without It Falling In?
The hard part is not removing the rock but stopping everything above from arriving in the hole, so the lining goes in as fast as the digging.
Let’s go →A very small parachute pointed the wrong way
Why Do Umbrellas Turn Inside Out?
An umbrella inverts because wind flowing over the dome lifts it from outside, and the ribs only brace against downward force.
Let’s go →The room does the pushing
Why Does Suction Pick Things Up?
Nothing sucks. The fan throws air out of the exhaust, the hose drops below room pressure, and the room's own air pours in carrying the dust.
Let’s go →Water carrying straight on
Why Does Spinning Get Clothes Dry?
A spin cycle throws nothing out. Water keeps travelling straight while the drum forces the clothes to curve away, so it leaves through the holes.
Let’s go →One push, turned sideways
Why Does a Sharp Edge Cut So Easily?
A wedge redirects your downward push sideways and concentrates it onto almost no area at all, which is the whole of why a sharp edge cuts.
Let’s go →A clock that survives being carried
Why Can a Watch Work on a Moving Arm?
A watch replaces the pendulum with a wheel swinging against a fine spring, which does not care which way up it is or how much it is jolted.
Let’s go →A Y-channel and a wedge
What Actually Joins a Zip?
Nothing inside a zip's slider ever changes: a Y-channel hooks the teeth together one way and a wedge prises them apart when you pull the other.
Let’s go →Space
Crashy night-sky stories — 24 stories.
All space →Leftover bricks
What Are Asteroids?
Asteroids are the bricks left over from planet-building — the rubble of a world that never managed to form, mostly parked between Mars and Jupiter.
Let’s go →Not what you think
Why Do Astronauts Float?
Gravity 400 km up is still 90 per cent as strong as at your feet. Astronauts float because the station falls around Earth and never lands — and so do they.
Let’s go →Gravity turned all the way up
What Is a Black Hole?
Pack matter tightly enough and escaping it would mean travelling faster than light. Nothing can, so nothing leaves — not even the light itself.
Let’s go →An island of stars
What Is a Galaxy?
We see the Milky Way as a band across the sky because we are sitting inside its flat disc, looking the long way along it from out on one arm.
Let’s go →Yes, lots
Is There Gravity in Space?
Gravity never switches off, it only gets gentler with distance, and it reaches everywhere. Space is full of it — which is why everything there is orbiting.
Let’s go →Neptune, 1846
The Planet Found With a Pencil
Neptune was found by arithmetic: Uranus was being pulled off its predicted path, and the calculation said exactly where the puller must be.
Let’s go →The edge is not a wall
What If You Fell Into a Black Hole?
Falling into a big black hole feels like ordinary falling — while anyone watching sees you slow, redden, and freeze at the edge forever.
Let’s go →A true space story
Where the Moon Came From
The Moon is the piece of Earth that got knocked loose and never fell back, thrown into the sky by one enormous crash into the young planet.
Let’s go →Measured by laser since 1969
The Moon Is Leaving, Four Centimetres a Year
The Moon is slowly being flung outward by the tides it raises, and the bill is paid by Earth's rotation — which is why days were shorter for the dinosaurs.
Let’s go →Leave most of the ship behind
How Did the Astronauts Get Back Off the Moon?
The bottom half kept the legs and the descent engine and simply stayed put. The cabin fired off it and only had to reach the ride waiting in orbit.
Let’s go →A star nursery
What Is a Nebula?
A nebula is a vast cloud of gas and dust: both the raw material that stars condense out of, and the wreckage they scatter when they die.
Let’s go →A city that weighs a sun
What Is Left After the Explosion?
A supernova leaves its crushed core behind: a ball the width of a city, holding more material than the Sun, spinning hundreds of times a second.
Let’s go →Falling without ever landing
What Is an Orbit?
An orbit is a permanent fall: move sideways fast enough and the ground below curves away exactly as quickly as you drop towards it.
Let’s go →Gravity pulls from all sides
Why Is Every Planet a Ball?
Anything big enough pulls itself into a ball, because gravity tugs equally from every side and rock is not strong enough to resist it.
Let’s go →Not friction
Why Do Spacecraft Get So Hot Coming Back?
A capsule coming home at eight kilometres a second is not rubbed hot by the air. It squashes the air in front of it, and squashed air glows.
Let’s go →Pushing on nothing
How Do Rockets Launch?
A rocket flies by throwing hot gas downward very fast. The recoil from that throw is what lifts it, with nothing outside to push against.
Let’s go →Fast enough to miss
How Do Satellites Stay Up?
A satellite is not floating, it is falling — sideways, so fast that Earth keeps curving away underneath it before it can ever arrive.
Let’s go →Billions of orbiting snowballs
What Are Saturn's Rings Made Of?
The rings are billions of separate ice chunks, each on its own orbit. They only look solid from far away, and the sheet is astonishingly thin.
Let’s go →Falling forever
Why Planets Orbit the Sun
A planet is not held on a string. It is falling towards the Sun and moving sideways fast enough to keep missing, over and over, forever.
Let’s go →A shell of debris
What Happens to Old Satellites?
Dead satellites and fragments keep orbiting for years, and at eight kilometres a second even a stray fleck of paint is dangerous.
Let’s go →Home at 28,000 km/h
Living on the Space Station
Sixteen sunrises a day, food that floats, and no such thing as a floor. Every ordinary habit has to be rebuilt for a place where nothing ever falls.
Let’s go →From a cold cloud
How Does a Star Get Started?
A star begins as a cold cloud of gas falling in on itself, and switches on when the squeezed centre finally reaches about ten million degrees.
Let’s go →The heaviest stars only
How Does a Star Explode?
A giant star spends its life holding itself up. When its core can no longer push back it falls in within a second, and the rebound tears it apart.
Let’s go →Tipped right over
Why Does Uranus Spin on Its Side?
Every other planet spins like a top. Uranus is tipped 98 degrees and rolls along its orbit like a barrel, giving each pole a forty-year summer.
Let’s go →Earth & sky
Weather, light, and the air around us — 22 stories.
All earth & sky →A weak layer buried inside
Why Does a Snowy Slope Suddenly Let Go?
An avalanche happens when a buried weak layer collapses under a rigid slab of snow, so the whole sheet lets go at once instead of sliding.
Let’s go →Ice you cannot see
Why Is Black Ice So Dangerous?
Black ice is transparent and bubble-free, so it looks exactly like wet road while removing very nearly all of your grip. You see it once you are on it.
Let’s go →Because it was one
Why Does the Map Look Like a Jigsaw?
South America and Africa fit together because they really were joined, and new sea floor forming between them has pushed them apart since.
Let’s go →How hard the air pushed
Why Is Some Rain Gentle and Some Rain Heavy?
Drizzle falls from a shallow cloud with no lift in it. A downpour falls from a tall one whose updraughts held the drops up until they had grown huge.
Let’s go →Rock finally slipping
Why Does the Ground Shake?
Earth's plates grind past one another, snag, and hold. The shaking is centuries of stored strain let go in seconds when the snag finally gives way.
Let’s go →Ice that flows
How Do Glaciers Move?
Pile ice deep enough and it stops behaving like a solid: it deforms and creeps downhill under its own weight, carving U-shaped valleys as it travels.
Let’s go →Ice going round again
How Does Hail Form?
A hailstone gains one layer per trip through a storm's updraught, thrown up and falling back until it is finally too heavy to be lifted again.
Let’s go →One-ninth showing
Why Do Icebergs Float So Low?
Ice is only slightly less dense than seawater, so an iceberg floats with roughly eight-ninths of itself hidden below the surface and out of sight.
Let’s go →You are already moving very fast
What If the Earth Stopped Spinning?
If Earth stopped turning, everything loose would keep going east at the speed of a rifle bullet — and the sea would slide off the middle of the planet.
Let’s go →Gravity does not care about the ground
What If the Earth Were a Cube?
A cube-shaped Earth would have eight corners sticking out above the air, and all the water and air pooled into six round seas.
Let’s go →Four different ways
How Does a New Island Appear?
Islands appear four different ways — a volcano building up, coral growing, land cut off by rising seas, or the sea dropping — and the shape shows which.
Let’s go →Building up and wearing down
Why Does Land Have Shapes At All?
Every hill and valley is a contest between forces shoving the land upwards and weather grinding it back down, settled by the rock underneath.
Let’s go →A slope losing an argument
Why Do Hillsides Slide?
Every slope is a slow argument between gravity and friction, and a landslide is the moment water, undercutting or shaking makes friction lose.
Let’s go →Hot, and solid anyway
Why Is the Inside of the Earth Not Liquid?
The Earth's inside is hot enough to melt but held solid by pressure — so magma is made by dropping the pressure or adding water, not by adding heat.
Let’s go →Crust crumpling
How Do Mountains Grow?
Mountains rise where colliding plates crumple the crust upward, and they last only as long as that uplift keeps ahead of the weather wearing them down.
Let’s go →Lifted, not built
Why Are Some Mountains Flat on Top?
A plateau is not a mountain that lost its peak — it is flat land lifted as one block, keeping its surface until rivers cut in from the edges.
Let’s go →Erosion on the outside
Why Do Rivers Bend?
Water runs fastest round the outside of a bend, so it cuts that bank and drops sand on the inner one. Every bend therefore makes itself a little sharper.
Let’s go →Wind piling up water
Why Does the Sea Rise in a Storm?
A funnel-shaped bay gives the water nowhere to escape, and the same surge arriving at high spring tide instead of low is what overtops a sea wall.
Let’s go →The Moon pulling
Why Does the Sea Go In and Out?
The Moon pulls the ocean into two bulges on opposite sides of the planet, and Earth turns through both, which is why high tide comes round twice a day.
Let’s go →A spin tipped upright
How Does a Tornado Form?
Winds at different heights roll the air into an invisible horizontal tube. A storm's updraught tips that tube upright and stretches it until it spins hard.
Let’s go →A wave that is all the way down
Why Are Tsunamis So Dangerous?
An ordinary wave is surface motion. A tsunami moves the entire depth of the ocean, so it carries far more water than its modest height at sea suggests.
Let’s go →Pressure finding a way out
Why Do Volcanoes Erupt?
Molten rock is lighter than the rock above it, so it rises. Dissolved gas expanding on the way up is what turns that rise into an eruption.
Let’s go →Everyday wonders
Kitchen, bubbles, echoes, and odd little magic — 16 stories.
All everyday wonders →Air pushing back
Why Does a Balloon Stay Blown Up?
Air molecules inside are constantly hitting the rubber, and their combined pushing outward exactly balances the stretched rubber pulling in.
Let’s go →A magnet inside a bigger magnet
How Does a Compass Work?
Earth is a giant magnet, and a compass needle is a small one pivoted loosely enough that it can swing round and line itself up with the field.
Let’s go →A skin that shoves the air
How Does a Drum Make a Sound?
A string's wobbles line up into a note; a round skin's do not, so a drum reads as a hit. The middle thuds, the edge rings and the rim gives a crack.
Let’s go →Ridges that grip and feel
Why Do We Have Fingerprints?
Fingertip ridges channel water away so wet things can still be gripped, and they turn fine texture into vibrations your touch sensors are able to read.
Let’s go →A squashed cable
Why Does Your Foot Go to Sleep?
It is the nerve being squeezed, not the blood supply, and the thick fibres wake first, which is why it goes tingling, then aching, then normal.
Let’s go →Two points beat one
Why Does a Fork Have Prongs?
A fork does not cut, it holds — and one point lets food spin away. A second locks it still, and the rest share the push so nothing tears.
Let’s go →The string is the point
Why Does a Kite Stay Up on a String?
Cut the line and a kite drops rather than climbs, and on a still day you can fly one by walking backwards. A wing only needs air moving past it.
Let’s go →Iron, made temporarily magnetic
Why Do Magnets Stick to the Fridge?
A magnet lines up the tiny magnetic regions inside the door's steel, making the fridge briefly a magnet too. What you feel is two magnets attracting.
Let’s go →A liquid that panics
Why Can You Run on Cornflour and Water?
Shove the grains together faster than the water between them can escape and they jam like a solid. Stop pushing and the mixture is a liquid again.
Let’s go →Trading height for distance
Why Does a Paper Plane Glide?
A paper plane does not fly so much as fall very slowly forwards, pushing air downwards with its wings and trading height for distance the whole way.
Let’s go →Tangled chains straightening out
Why Do Rubber Bands Snap Back?
Rubber is a mass of tangled molecule chains. Stretching straightens them, and they snap back for the simple reason that tangled is far more likely.
Let’s go →All the force in one line
Why Is a Sharp Knife Safer Than a Blunt One?
A sharp edge is a few hundred atoms across, so almost any push cuts. A blunt one makes you lean on it, and a skid sends that stored force somewhere else.
Let’s go →Air pressure pushing from outside
How Does a Straw Work?
You never pull a drink upwards. You lower the pressure in the straw and the atmosphere pushes the drink up for you — which caps any straw at ten metres.
Let’s go →Pushing in time
How Do You Make a Swing Go Higher?
A swing has exactly one natural rhythm. Pumping works by feeding it a little energy in time with that rhythm, arc after arc, until the arc is huge.
Let’s go →Your brain saw it coming
Why Can't You Tickle Yourself?
A machine that copies your own hand movement half a second late really does tickle you, because the prediction your brain made no longer lines up.
Let’s go →Thousands of tiny hooks
How Does Velcro Stick?
One side is thousands of stiff hooks, the other thousands of soft loops. Together they resist a flat pull hugely and give up at once to a peel.
Let’s go →Animals
Creatures on land, in the sea, and in the air — 15 stories.
All animals →Everything about it is built for lightness
How Does a Bird Stay Up?
A bird bends passing air downwards off its curved wings, and almost every part of it — hollow bones, enormous chest muscles — pays for that.
Let’s go →Turning round in mid-air
Why Does a Cat Always Land on Its Feet?
A falling cat has nothing to push against, and turns over anyway: it tucks one end in and leaves the other out, then swaps, twisting each half in turn.
Let’s go →Four wings, four motors
How Does a Dragonfly Fly Backwards?
Each of a dragonfly's four wings has its own muscles, so it can aim the push anywhere — which is how it hovers, reverses and turns on the spot.
Let’s go →Everyone gets a tow except one
Why Do Geese Fly in a V?
Each bird rides the swirl of rising air spilling off the wingtip ahead, which is real work saved. They take turns at the front, where there is none.
Let’s go →Seven bones, same as yours
Why Is a Giraffe's Neck So Long?
A giraffe has the same seven neck bones you do, each one enormous, plus a very strong heart and valves that let it survive bending down.
Let’s go →Standing on almost nothing
How Do Goats Climb Cliffs?
A goat stands on ledges narrower than its own hooves. Each hoof splits into two toes with a hard gripping rim around a soft rubbery pad.
Let’s go →Everything else was left behind
Why Do Horses Run on One Toe?
A hoof is a single huge toenail, and losing the other toes made the leg light at the bottom, which is what makes a horse fast.
Let’s go →A leg that locks
Why Do Horses Sleep Standing Up?
A hook of bone clicks a horse's knee into a catch, so standing costs no muscle and it can doze upright, lying down only for its deepest sleep.
Let’s go →Getting your energy back
Why Does a Kangaroo Hop?
A kangaroo's tendons store and return energy like springs, so hopping fast costs it almost nothing more than hopping slowly does.
Let’s go →A fifth hand
Why Can a Monkey Hang by Its Tail?
African and Asian monkeys never evolved one in thirty million years of similar forest — a reminder that evolution does not find every good answer.
Let’s go →One foot, one shell, no hurry
How Does a Snail Carry Its House?
Snail slime grips when it is pressed slowly and turns slippery when pushed hard, which is how a snail climbs glass without ever sliding back down.
Let’s go →A whole body doing the work of feet
How Does a Snake Move With No Legs?
A forked tongue samples two places at once, so a snake smells in stereo, and its jaw comes in two halves that walk over a meal wider than its head.
Let’s go →Nobody is in charge
How Does a Flock Turn All at Once?
A thousand birds turn together in a fraction of a second with no leader at all, because each one follows a few rules about its neighbours.
Let’s go →One part, a dozen jobs
What Is a Tail For?
A tail can be a rudder, a balance pole, a fifth limb, a fly swat, a blanket or a shout across a field — whatever that animal needs most.
Let’s go →Hitting a tree, all day
Why Doesn't a Woodpecker Get a Headache?
It hammers wood twenty times a second and walks away fine. Being small is most of the reason: a tiny brain packed tight has no room to slosh.
Let’s go →What things are made of
Atoms, metal, glass, plastic, and every kind of stuff — 8 stories.
All what things are made of →Wrong-sized atoms get in the way
Why Is Pure Gold Too Soft for a Ring?
A pure metal bends because its atoms slide in neat rows. Mix in a differently sized atom and the rows jam, which is why alloys beat what went into them.
Let’s go →Twist turns short fibres into long ones
How Does Fluff Become Thread?
Twisting short fibres squeezes them hard against one another, and the friction between them is enough to make the whole bundle behave as one long strand.
Let’s go →Flow into every crevice, then stop flowing
How Does Glue Hold Two Things Together?
Two flat-looking surfaces touch at only a few high points, so glue has to be runny enough to flood every tiny pit, and then stop being runny.
Let’s go →A thread made from nothing that grew
Why Was Nylon Invented?
Nylon was the first useful fibre that came from neither plant nor animal: long molecule chains pulled straight, endless and rot-proof.
Let’s go →Twist, and twist again
Why Is a Rope Stronger Than Its Threads?
Pulling on a rope does not stretch its fibres apart, it squeezes them together — so friction stops any short fibre from ever sliding out.
Let’s go →Tangled springs
Why Does Rubber Bounce Back?
Stretching a rubber band pulls no molecules apart. It straightens tangled ones, and they scramble back into knots the moment you let go.
Let’s go →A pinch of carbon changes everything
What Makes Steel Stronger Than Iron?
Add about one percent carbon to iron and it becomes several times stronger, because the carbon jams the layers that used to slide past.
Let’s go →A bundle of drinking straws
Why Does Wood Split One Way?
One pale band of spring growth plus one dark band of late summer is a single year of the tree. Plywood works by leaving no easy direction to split.
Let’s go →Life & body
Seeds, hearts, senses, and growing things — 8 stories.
All life & body →Stiff and springy together
What Are Bones Made Of?
Bone is a hard mineral laced with a stretchy protein, so it is strong without being brittle. It is also hollow, alive, and rebuilt thicker where loaded.
Let’s go →Fluid that keeps going
Why Does Spinning Make You Dizzy?
Three loops of liquid in each ear sense turning, and when you stop the liquid does not, so your ears insist on a spin your eyes deny.
Let’s go →A backstop for your fingertip
What Are Fingernails For?
Fingernails are a hard backstop that lets your soft fingertip press against something, making fine touch and picking things up possible.
Let’s go →Only ever pulling
How Do Muscles Move You?
Muscles can only pull, never push, so they come in opposing pairs and use bones as levers to turn a short pull into a much larger movement.
Let’s go →It is holding your neck, not your head
Why Does a Pillow Help You Sleep?
Lying down leaves a gap between your head and the mattress. A pillow fills it, so no neck muscle has to hold your head up for seven hours.
Let’s go →Blasting the nose clear
Why Do We Sneeze?
A sneeze is a reflex, not a decision: irritated nerves in your nose trigger a blast of air fast enough to clear them — and to spread germs remarkably well.
Let’s go →Several senses at once
How Does Touch Work?
Touch is not one sense but several — pressure, temperature, pain and stretch — and most of it reports change rather than steady contact.
Let’s go →Borrowing someone else's trunk
Why Do Vines Climb?
Building a trunk is enormously expensive, so a vine grows thin and fast, grabs a support somebody else built, and spends the rest on leaves.
Let’s go →Math
Number ideas with toys — 1 story.
All math →