mathematics
When a dog runs at a duck swimming across a pond, the dog's path traces a pursuit curve. Pierre Bouguer worked out the mathematics in 1732. The same equations describe missile guidance, predator-prey dynamics, hot-pursuit problems in epidemiology, and the spiral arms of certain galaxies.
history
The well is the oldest piece of civic infrastructure that still works the way it did when it was invented. The Bronze Age innovations that solved problems we have largely forgotten existed, the strange persistence of medieval technology into the present, and the deep-aquifer engineering that qu
mathematics
Random numbers are simultaneously the most familiar and the most subtle objects in mathematics. The century of false starts, the philosophical puzzle of what randomness even means, the practical engineering of generators that fool sophisticated tests, and the cryptographic stakes when the engin
history
In 1942, the most beautiful woman in Hollywood patented a frequency-hopping spread spectrum system that the US Navy ignored, the FCC eventually ratified, and Bluetooth, GPS, and WiFi all use today. The story of Hedy Lamarr's other career — and what it reveals about who gets to be a scientist.
history
Movable type is taught as a single Gutenberg moment, but the real story is a multi-century convergence of metallurgy, ink chemistry, papermaking, and an institutional appetite for cheap text. The revolution was less about the press itself than about the social infrastructure that grew up around
history
For three thousand years, lighthouses were the highest engineering achievements of their time and the largest civic investment most cities ever made. They were built from stones that had to outlive empires, lit by fuels that had to be invented, and operated by keepers whose isolation produced its...
mathematics
Every storage device, every transmission, every QR code, every deep-space probe, every CD, every cell phone signal, every satellite link — they all rely on a class of mathematical structures invented in 1950 by a frustrated Bell Labs engineer who could not get his program to run over the weekend....
history
Before 1883, every American city kept its own time, set by the local sun. Boston was 11 minutes ahead of New York, which was 5 minutes ahead of Philadelphia. Trains made this intolerable. The story of how four time zones replaced thousands of local solar times is a story about coordination proble...
math
In 1852 a London graduate student noticed he could color any map of England with four colors so that no adjacent counties shared a color. The conjecture took 124 years and the first major computer-assisted proof in mathematical history to settle. The story illuminates how a question that sounds
history
Roman aqueducts moved 1.1 million cubic meters of water per day across continental distances using only gravity and sub-millimeter-per-meter gradients. The engineering required surveying instruments accurate enough to maintain a fall of 30 cm per kilometer over 100 kilometers — a precision that
history
The postal system is one of the most successful pieces of infrastructure in human history, and its inventions — the relay station, the postage stamp, the registered letter, the parcel — have quietly shaped the modern world. The history is older and stranger than the institution suggests.
history
For 2000 years, philosophers insisted nature abhors a vacuum. Then a student of Galileo built a tube of mercury in 1643 and showed that the abhorrence was a mistake. The history of vacuum is the history of the slow recognition that emptiness is not what we thought it was.