It used to be thought that the world was flat. That beyond the horizon lurked a bottomless void, measureless to humans. As our ships got better and our navigators more confident, vessels that disappeared over one horizon began returning triumphant from the other. The Earth was curved, a sphere with no edges. We didn’t fall off because a mysterious force called gravity kept everyone and everything stuck to the planet’s surface.
Then Albert Einstein came along and told us that space itself was curved. Now we realise that if we sail off into the sea of curved space we call the Universe ... Read even more
