Release Message:  A sphere can, topologically, be turned inside out. Authored by Stephen Smale.

Description:  In differential topology, Smale's paradox states that it is possible to turn a sphere inside out in a three-dimensional space with possible self-intersections but without creating any crease, a process more commonly and historically called sphere eversion (eversion means "to turn inside out"). This is surprising, to those who understand regular homotopy, and is hence deemed a veridical paradox.