Turtles All the Way Down

I first read the phrase “Turtles All the Way Down” in a book by Stephen Hawking. According to the story, a big name scientist was giving a lecture on astronomy.
After the lecture, an elderly lady came up and told the scientist that he had it all wrong. ‘The world is really a flat plate supported on the back of a giant tortoise.” The scientist asked “And what is the turtle standing on?”
To which the lady triumphantly replied: “You’re very clever, young man, but it’s no use — it’s turtles all the way down.”