Big Bang Theory: Kal Penn, Sean Astin cast in final season

The Big Bang Theory’s Sheldon and Amy are getting an assist with their super-asymmetry theory — and something tells us Dr. Cooper will be none too pleased.

The CBS sitcom has cast Kal Penn (Designated Survivor) and Sean Astin (Stranger Things) to guest-star in an upcoming episode as Drs. Campbell and Pemberton, a team of physicists who accidentally confirm the marrieds’ complex scientific concept, TVLine has learned. An airdate has not been announced.

As fans will recall, Sheldon and Amy thought their super-asymmetry theory had been disproven by a Russian paper. Then, in the Dec. 6 episode, the theoretical physicist and his wife came to a breakthrough and realized that the paper was only right from one perspective, which meant their theory was still sound.

Penn most recently co-starred opposite Kiefer Sutherland in the first two seasons of Designated Survivor, which will soon relocate from ABC to Netflix. Astin, meanwhile, will follow-up his Stranger Things stint with a starring role in Netflix’s multi-camera family comedy No Good Nick.

The Big Bang Theory‘s 12th and final season resumes Thursday, Jan. 3 at 8/7c on CBS.