10 Times Humanity Found the Answer (and Then Forgot)

The Power of Steam
Watching an aeolipile do its work was the equivalent of a Netflix binge back in the day. Liszt Collection/Heritage Images/Getty Images

In the Tom Stoppard play "Rosencrantz and Guildenstern Are Dead," dimwitted Rosencrantz repeatedly stumbles onto notable scientific and technical discoveries, often via toys (neither he nor Guildenstern grasp what he's done). These droll scenes raise a thorny question: Do you have to recognize a thing's operational principle to lay claim to discovering it? Should we credit the inventor of a steam-driven toy with the discovery of steam power?

Whatever your answer, there's no question that the aeolipile, a toy devised in the first century by inventor Heron of Alexandria, was a steam turbine — a device that turns the thermal energy of escaping steam into mechanical energy. As far as we know, Heron's device — a water-fed sphere, mounted on its axis above a heat source, that spun thanks to steam escaping from two bent tubes sticking out from its middle —never attained more than amusement status. But the idea that inventors would begin to re-examine in the 17th century, and that would drive the Industrial Revolution during the late 18th and early 19th centuries, was there — regardless of whether anyone in Heron's time grasped why it worked [sources: Encyclopedia Britannica, Martin, Palermo].

Interestingly, Heron himself collected ancient knowledge, so as some of his works were lost — some briefly, some forever — so too were stockpiles of ancient Babylonian, Egyptian, Greek, and Roman math and engineering progress [source: Encyclopedia Britannica].