What follows is — depending on how you want to think about it — either a gallery of technologies we lost or an invitation to consider alternate futures. Some of what might have been is fantastical: a subway powered by air, an engine run off the heat of your palm. Some of what we lost, on the other hand, is more subtle, like a better way to bowl or type. As new standards emerge, variety fades, and a single technology becomes entrenched. (That’s why the inefficient Qwerty keyboard has proved so difficult to unseat.)

We can take heart, however, in the fact that good ideas never disappear forever; the Stirling engine didn’t pan out in the Industrial Revolution, for example, but it can keep the lights on for a small village. As you look through the images, then, please consider not only what might have been but what could still be again. — RYAN BRADLEY