"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."
"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 )