Proofs of Concept


The first iterations of a new technology can seem astonishingly clunky, at least in retrospect. Often, they are more a proof of concept than a practical device.

The first hydrogen bomb, detonated in 1952, was the size of a three-story house and weighed 82 tons. No airplane in the world could have carried it. Within little more than a decade, however, the thermonuclear warheads atop missiles were roughly the size of garbage cans and weighed less than 700 pounds.

A century and a half earlier, the first steam engines were very large and heavy relative to the power they produced. The big engines that drove the Philadelphia waterworks in the early 19th century — the largest steam engines in the country at the time — were built using James Watt’s low-pressure design. They had 32-inch cylinders with a stroke of six feet. But they only put out 12 horsepower. Even the more-efficient high-pressure engines, independently designed by Oliver Evans in the U.S. and Richard Trevithick in Britain, were bulky, and they were ravenous consumers of coal.