Physics department colloquium with William Zajc on the nature of the quark-gluon plasma being investigated at the Relativistic Heavy Ion Collider at Brookhaven. The plasma behaves like a perfect fluid, having a very small viscosity to entropy density ratio. In fact, there is an uncertainty-relation based argument that puts a lower bound on this quantity, and the quark-gluon plasma seems to be near it.
What is it for superfluid helium? Is the quark-gluon plasma a type of superfluid? Does it have any collective excited states that we can probe?
