I actually know Krister in person - through the Banff Science Communications Program. Krister is awesome - he is a physicist, he dances (lindy hop), and he writes on his blog "The Dancing Physicist" (http://www.dancingphysicist.com/).
Note: a newer version of the talk can be found here - http://www.dancingphysicist.com/quantum-physics-harry-potter/
"The universe of Harry Potter is filled with magic and wonder. Yet it is not that different from the world we inhabit."
Via Sakis Koukouvis