It's cranes all the way down

From Stephen Hawking's 1988 book A Brief History of Time:

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: "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!"

So have you ever gone past a construction site and wondered how those giant cranes towering far above the site get there? The answer is, of course, another crane, which puts us in a sort of chicken and egg situation.

Actually, the smaller crane builds the base, and then through a clever assembly, the new crane is actually able to add vertical sections to itself as in place as needed, growing along with the building.

Warning: The music underneath is pretty obnoxious, so you may want to kill the volume. (via Wired.com's Gadget Lab)




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