turtles all the way down

“My goal is simple. It is complete understanding of the universe, why it is as it is and why it exists at all.”
—Stephen Hawking, 1981

Stephen Hawking opens his new book with a marvelous old anecdote. A famous astronomer, after a lecture, was told by an elderly lady, who was perhaps under the influence of Hinduism, that his cosmology was all wrong. The world, she said, rests on the back of a giant tortoise. When the astronomer asked what the tortoise stands on, she replied: “You’re very clever, young man, very clever. But it’s turtles all the way down.”

Most people, Hawking writes, would find this cosmology ridiculous, but if we take the turtles as symbols of more and more fundamental laws, the tower is not so absurd. There are two ways to view it. Either a single turtle is at the bottom, standing on nothing, or it’s turtles all the way down. Both views are held by leading physicists. David Bohm and Freeman Dyson, to mention two, favor the infinite regress—wheels within wheels, boxes inside boxes, but never a final box.¹ Hawking is on the other side. He believes that physics is finally closing in on the ultimate turtle.

--  Review of A Brief History of Time: From the Big Bang to Black Holes by Stephen W. Hawking