In three spatial dimensions, it is a close relative of the quark-gluon plasma, the super-hot state of matter that hasn't existed since the tiniest fraction of a second after the big bang that started the universe. When viewed in 10 dimensions, the minimum number prescribed by what physicists call "string theory," it is a black hole.
No matter what you call it, though, that substance and others similar to it could be the most-perfect fluids in existence because they have ultra-low viscosity, or resistance to flow, said Dam Thanh Son, an associate physics professor in the Institute for Nuclear Theory at the University of Washington.