A 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: ΓÇ£What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise.ΓÇ¥ The scientist gave a superior smile before replying, ΓÇ£What is the tortoise standing on?ΓÇ¥ ΓÇ£YouΓÇÖre very clever, young man, very clever,ΓÇ¥ said the old lady. ΓÇ£But itΓÇÖs turtles all the way down!ΓÇ¥
Most people would find the picture of our universe as an infinite tower of tortoises rather ridiculous, but why do we think we
