The idea that a machine might think is older than computers themselves. In the 17th century, Leibniz imagined a calculus of reasoning that could settle any dispute through mechanical calculation. In the 19th century, Ada Lovelace speculated about the capabilities and limits of Charles Babbage’s proposed Analytical Engine. But the…

When President Kennedy declared in 1961 that the United States would land a man on the Moon before the end of the decade, he did not specify where on the Moon that landing would occur. This was not a trivial detail. The Moon’s surface is 14.6 million square miles of…

We all carry images of scientists in our heads. Newton with his long silver hair. Einstein with his wild white mane. Darwin with his enormous beard. Curie with her steady, penetrating gaze. These images are so familiar that they feel natural, as if the scientists simply looked that way. But…

When World War I broke out in August 1914, Marie Curie was fifty-six years old, a two-time Nobel laureate, and the most famous scientist in France. She had discovered polonium and radium. She had proved that radioactivity is an atomic property. She held the chair of physics at the Sorbonne,…

In May 1899, Nikola Tesla arrived in Colorado Springs, Colorado, with a single assistant, a suitcase of notes, and a plan to build the most ambitious electrical laboratory the world had ever seen. Over the next eight months, he would generate artificial lightning bolts over 130 feet long, light electric…

Between 1943 and 1951, a small group of engineers, mathematicians, and physicists at the University of Pennsylvania built two machines that launched the computer age. The first, ENIAC (Electronic Numerical Integrator and Computer), proved that electronic computation was possible. The second, EDVAC (Electronic Discrete Variable Automatic Computer), introduced the stored-program…

Around 585 BCE, in the middle of a battle between the Lydians and the Medes in what is now Turkey, the sky went dark. A total solar eclipse turned day into night. Both armies, terrified by what they interpreted as a divine warning, immediately ceased fighting and negotiated peace. According…

The phone in your pocket, the laptop on your desk, the servers that run the internet, and the supercomputers that simulate climate models all share the same fundamental architecture. They all store programs and data in the same memory. They all fetch instructions one at a time from that memory,…

In 1824, a young French military engineer named Sadi Carnot published a slim book with an unassuming title: Réflexions sur la puissance motrice du feu (Reflections on the Motive Power of Fire). It sold poorly. It was reviewed by almost nobody. Carnot died eight years later, at thirty-six, during a…

In 1805, the French mathematician Adrien-Marie Legendre published a book on the orbits of comets. Buried in an appendix was a mathematical technique he called the “method of least squares,” a procedure for fitting a curve to a set of data points by minimizing the sum of the squared differences…