A brief history of time, by Stephen Hawking WELL KNOWN SCIENTIST
(Some say it was Bertrand Russell) once
gave a public lecture on astronomy. He described how the earth
orbits around the sun and how the sun, in turn, orbits around the center of a vast collection of stars called our galaxy. At the end of the lecture. a little old lady at the back of the room got up and said: "What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise." The scientist gave a superior smile before replying, "What is the tortoise standing on?" "You're very clever, young man, very clever," said the old lady. "But it's turtles all the way down!'
Most people would find the picture of our universe as an infinite tower of tortoises rather ridiculous, but why do we think we know better? What do on know about the universe, and how do we know it?
