How curious things actually work, from rockets to codebreaking.
Written and illustrated by Ethan Newell.
Have you ever watched a rocket the height of a building fall back from space and land upright on a ship? The first time I saw it, I honestly thought the video was fake. It isn't. And the way it works comes down to a handful of simple ideas you can pick up in an afternoon.
This book is full of questions like that. How does a drone hover perfectly still in a gusty wind? How did a wartime code machine turn the same letter into a different one every single time? How does your phone know where you're standing?
Each chapter starts with something curious and keeps digging until it reaches the simple idea underneath.
A tiny computer checks how it's tilting hundreds of times a second. When a gust tips it, it speeds up the motors on the low side until it's level again. It never stops making those little fixes.
Every key press sends electricity through three wired wheels and back again. Then the wheels turn, so typing HELLO twice gives you two completely different jumbles. A few mathematicians still found a way in.
A moving car really wants to keep going straight. On a bend, the grip of the tyres is what pulls it round. Hit a patch of ice and that grip disappears, so the car just carries on in a straight line.
Every satellite keeps broadcasting the exact time. How late each signal arrives tells your phone how far away that satellite is. With four of them, there's only one spot on Earth you can be.
A tiny microphone listens to the noise around you, and the speaker plays the exact opposite sound. Where one pushes the air, the other pulls, and the two cancel out into something close to silence.
A wing is tilted slightly, so as it moves it shoves a huge amount of air downwards. Push air down and the air pushes the wing up. That push is called lift.
Drop a hammer and a feather at the same time and the hammer wins, every time. The feather takes its time, rocking from side to side on the way down.
But gravity isn't what's holding the feather back. It's the air. Pump the air out of the tube and watch what happens: they fall side by side and land at exactly the same moment.
In 1971, an astronaut tried this on the Moon, where there's no air at all. He let go of a hammer and a feather together, and they hit the dusty ground at the same instant. It's one of my favourite bits of film ever.
If you've ever wondered how something works and never got a straight answer, this book is for you.
School tends to teach the idea first and the interesting thing later, if it gets there at all. I wanted to flip that round. Every chapter starts with the rocket, the drone or the code machine, and keeps going until it reaches the simple idea underneath.
Each chapter is packed with animated diagrams you can watch, poke and replay. You don't need any maths to follow along, but it's there at the end if you want it.
Read a few and you'll start spotting the same handful of ideas everywhere: in rockets, in headphones, in the car you drive. That's the moment science stops feeling like a list of facts and starts feeling like a superpower.
The book is out now in early access. New chapters arrive as I finish them, and every update is free. When the book is complete, the price goes up to $79.