Essays
Before clocks, time was local. Noon was when the sun was highest, and that happened at a different moment for every town a few miles east or west. This did not matter when the fastest communication wa
Essays
In the seventh century, the Indian mathematician Brahmagupta wrote rules for computing with a number that represented nothing. He called it shunya — "the void." He defined rules that seem obvious toda
Essays
The oldest known map is a Babylonian clay tablet from around 600 BCE. It shows Babylon at the center of the world, surrounded by a circular ocean, with mysterious islands at the edges where heroes and