Astronomers have uncovered hints that there may be cosmic strings – lines of pure mass-energy – stretching across the entire Universe. Cosmic strings are predicted by high energy physics theories, including superstring theory. This is based on the idea that particles are not just little points, but tiny vibrating bits of string Cosmic strings are predicted to have extraordinary amounts of mass – perhaps as much as the mass of the Sun – packed into each meter of a tube whose width is less a billion billionth of the size of an atom.