Turtles all the way down

Turtles all the way down refers to a myth about the nature of the universe (see Cosmology). Stephen Hawking in his 1988 book A Brief History of Time starts with an anecdote about an encounter between a scientist and an "old lady."

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 centre 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."

The anecdote in this form has achieved the status of an urban legend on the internet, as there are numerous versions in which the name of the scientist varies (e.g., Thomas Huxley, William James, or Carl Sagan) although the rest is the same.

An earlier published version of this anecdote is found in an essay by Clifford Geertz, "Thick Description: Towards an Interpretive Theory of Culture," in his 1973 book The Interpretation of Culture:

There is an Indian story — at least I heard it was an Indian story — about an Englishman who, having been told that the world rested on a platform which rested on the back of an elephant which rested in turn on the back of a turtle, asked (perhaps he was an ethnographer; it is the way they behave), what did the turtle rest on? Another turtle. And that turtle? "Ah, Sahib, after that it is turtles all the way down."

This may be a reference to the Hindu belief that Vishnu's second avatar was Kurma, a tortoise on whose back the Mandara mountain rested. According to another Hindu myth, the tortoise Chukwa supports the elephant Maha-pudma, which upholds the world.

In the urban legend version, the anecdote is of a confrontation between a scientist and a lay-person; in the Geertz version, it is of a confrontation between colonizer and colonized.

This difference in the form of the anecdote serves the different uses to which the anecdote is put. For Hawking, the turtle myth is one of two accounts of the nature of the universe; he asserts that the turtle theory is patently ridiculous, but admits that his own theories may be just as ridiculous. "Only time will tell," he concludes. For Geertz, however, the myth is patently wise, teaching us that we will never get to the bottom of things. This comparison also reveals a difference between the positivist and interpretive, or hermeneutic approach to the interpretation of myths. Positivists read myths literally and find them false and foolish; interpretivists read them metaphorically or allegorically and find them true and profound.

In popular Discworld fantasy parody books by Terry Pratchett, the Discworld is a flat disc that rests on the backs of four huge elephants which are in turn standing on the back of an enormous turtle as it slowly swims through space.

In the 1940 film version of The Thief of Bagdad, this dialogue occurs between the protagonist (Abu) and a giant genie, while they are flying above the Himalaya:

Abu: "Where are we now?" Genie: "Above the roof of the world!" Abu: "Has the world got a roof?" Genie: "Of course! Supported by seven pillars. And the seven pillars are set on the shoulders of a genie whose bigness is beyond thought. And the genie stands on an eagle, and the eagle on a bull, and the bull on a fish, and the fish swims in the sea of eternity!"