Dark energy: No, seriously, what the heck is it?

The fun thing about the Nobel Prize in Physics is watching pundits try to explain to the public the research that won. It doesn't always go well. Physics is not, shall we say, the public's best subject. (And I include myself in that "public".) Beyond that, words that describe legitimate concepts in physics have taken on new, more fantastical meanings in science fiction, which only serves to confuse people further.

That's why I like this video produced by KQED Science. It features Lawrence Berkeley Lab astrophysicist Saul Perlmutter, one of the winners of this year's Nobel Prize in Physics, and does a nice job of explaining what "dark energy" really is, why work with dark energy is worthy of a Nobel, and what Perlmutter and his colleagues have contributed to the expansion of human knowledge.

Video Link