"Supersymmetry" is the fifth episode of season four of the Americanvampire series Angel and is the seventy-second episode of the series overall. The episode was directed by Bill L. Norton and written by Elizabeth Craft and Sarah Fain, based on characters and concepts originally developed by Joss Whedon and David Greenwalt. It first aired on the WB Network on Sunday, November 3rd, 2002. In this episode, Fred discovers that one of her science papers has been published and she has been invited as a guest speaker at the 31st Annual California Physics Institute Symposium. Wolfram & Heart lawyer Lilah Morgan pays Wesley Wyndam-Pryce a surprise visit and they engage in another of their growing string of one nights stands. Angel and Gunn attend Fred's speech at the symposium, but things get hairy when a mystic portral opens, disgoring a giant serpent creature that attacks Fred.
Supersymmetry is a concept in particle physics that relates elementary particles of one spin to other particles that differ by half a unit of spin and are known as superpartners.
There is a rather obvious plug to comic publisher Dark Horse Comics in this episode in the scene where Gunn is harassing the comic book store clerk. Dark Horse Comics was the first publisher to license the rights to publish Buffy the Vampire Slayer and Angel comic books.