(In case you didn't catch that fine joke: "The Banach–Tarski paradox [...] states the following: Given a solid ball in three-dimensional space, there exists a

(In case you didn't catch that fine joke: "The Banach–Tarski paradox [...] states the following: Given a solid ball in three-dimensional space, there exists a decomposition of the ball into a finite number of disjoint subsets, which can then be put back together in a different way to yield two identical copies of the original ball." https://en.wikipedia.org/wiki/Banach–Tarski_paradox https://en.wikipedia.org/wiki/Banach–Tarski_paradox )