Jan. 3 (UPI) -- Sean Astin and Kal Penn are set to guest-star on an upcoming episode of The Big Bang Theory which is currently in its 12th and final season.
The theory is a scientific breakthrough that could change the lives of Sheldon and Amy. An airdate for the episode has yet to be announced.
The Big Bang Theory's 12th and final season airs Thursdays at 8 p.m. on CBS. The comedy is set to conclude in May.
Penn, of Harold and Kumar fame, will next be reprising his role on Designated Survivor which is moving from ABC to Netflix.