Orrery
Working models of ideas.
An orrery is a clockwork model of the solar system. It doesn’t tell you that the planets move; it lets you turn the crank and see. Each exhibit here tries to do the same for one idea: a short essay with pictures you can drag, dials you can turn, and plain words around them.
Orrery is a small studio that makes these models. Every exhibit names its sources, says plainly what its model leaves out, and works offline, on a phone and with a keyboard.
Exhibits
- How does a machine learn from examples? — Nobody writes the rules into a neural network. So where do they come from?
- Why do two people in 23 probably share a birthday? — In a room of 23 people, a shared birthday is more likely than not. Why do so many people guess far lower?
- Better in every group, worse overall? — How can a treatment win for small kidney stones and for large ones, yet lose overall?
- Does a better gene always win? — A new mutation that helps its carriers should spread. Why do most of them vanish?
- How does a scratched CD still play? — A scratch wipes out thousands of bits at once. Why doesn't the music stop?
- Why are there two tides a day? — The Moon pulls the sea towards it — so why is there a high tide on the far side too?
- Why doesn’t the Moon fall down? — It does fall, all the time. It just keeps missing the Earth.
- Why is the sky blue and the sunset red? — Air is transparent and sunlight is white. So where do the blue sky and the red sunset come from?
- How can two strangers agree on a secret in public? — Two machines that have never met agree on a secret while anyone can listen. How?
- Where do traffic jams come from when nothing’s wrong? — No crash, no roadworks, no merge — and still you crawl. How do drivers make a jam out of nothing, and why does it travel backwards?
- Why do bell curves show up everywhere? — Heights, errors and test scores all make the same hump. Why — and when don't they?
- Why does the Moon have phases? — It isn't Earth's shadow. Drag the Moon round its orbit and see what is really going on.
- Why is a rainbow round? — You can never walk to a rainbow, and the person beside you sees a different one. What is it, and why is it always part of a circle?
- Can circles draw anything? — Why does Mars sometimes go backwards — and can circles on circles trace any shape?
- How many people need to be immune? — Why does measles need about 95% vaccinated, when other infections need far less?
- Where are the planets tonight? — The planets are somewhere specific right now. Where, and why do they sometimes seem to run backwards?
- Why can’t we forecast the weather a month ahead? — Two pendulums started a millionth of a radian apart soon do completely different things. Why doesn’t exact physics mean exact forecasts?
- Why is summer warm? — Earth is closest to the Sun in January. So why is July the warm month in the north?
- Why is the other line always faster? — A checkout busy 80% of the time already has a queue. Why do waits explode near full capacity — and why is your line so rarely the fast one?
- You tested positive. Now what? — A 99%-accurate test says you have a rare disease. Why is the chance you're sick only about 9%?