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.

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'Big Bang Theory' star Johnny Galecki through the years
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'Big Bang Theory' star Johnny Galecki through the years
Actress Carol Kane and actor Johnny Galecki attending the premiere of 'Lemmon Sisters' on August 27, 1990 at Mann Plaza Theater in Westwood, California. (Photo by Ron Galella, Ltd./WireImage)
UNITED STATES - MARCH 04: ROSEANNE- 'Gallery' 1991 Sara Gilbert, Johnny Galecki (Photo by ABC Photo Archives/ABC via Getty Images)
UNITED STATES - OCTOBER 16: ROSEANNE - On set in New York - 10/16/93, Sara Gilbert (Darlene), Johnny Galecki (David) on the ABC Television Network comedy 'Roseanne'. 'Roseanne' is the story of a working class family struggling with life's essential problems., (Photo by ABC Photo Archives/ABC via Getty Images)
American actress Sara Gilbert, with elastic bandage on wrist, and Belgian-born actor Johnny Galecki. (Photo by Kevin Winter/DMI/The LIFE Picture Collection/Getty Images)
UNITED STATES - SEPTEMBER 28: ROSEANNE - 'Party Politics' - Season Six - 9/28/93, Johnny Galecki (David), Sara Gilbert (Darlene) on the ABC Television Network comedy 'Roseanne'. Jackie and Roseanne plan a house-warming party for Jackie's new home., (Photo by ABC Photo Archives/ABC via Getty Images)
UNITED STATES - MARCH 08: ROSEANNE - 'Gallery' 1993 Johnny Galecki (Photo by ABC Photo Archives/ABC via Getty Images)
LOS ANGELES, CA - 1995: Actor Johnny Galecki poses for a portrait while attending an event circa 1995 in Los Angeles, California. (Photo by Ron Davis/Getty Images)
Actor Johnny Galecki attends the Bed of Roses Century City Premiere on January 18, 1996 at Cineplex Odeon Century Plaza Cinemas in Century City, California. (Photo by Ron Galella, Ltd./WireImage)
NASHVILLE, TN - JUNE 07: Actor Johnny Galecki attends the 2017 CMT Music Awards at the Music City Center on June 7, 2017 in Nashville, Tennessee. (Photo by Michael Loccisano/Getty Images For CMT)
LOS ANGELES - MARCH 28: 'The Separation Agitation' -- Pictured: Leonard Hofstadter (Johnny Galecki) and Penny (Kaley Cuoco). Coverage of the CBS series THE BIG BANG THEORY, scheduled to air on the CBS Television Network. (Photo by Sonja Flemming/CBS via Getty Images)
LOS ANGELES, CA - FEBRUARY 02: Actor Johnny Galecki attends a screening of 'Rings' at Regal LA Live Stadium 14 on February 2, 2017 in Los Angeles, California. (Photo by Jason LaVeris/FilmMagic)
LOS ANGELES, CA - JANUARY 29: Actor Johnny Galecki attends the 23rd Annual Screen Actors Guild Awards at The Shrine Expo Hall on January 29, 2017 in Los Angeles, California. (Photo by Steve Granitz/WireImage)
NEW YORK, NY - JANUARY 20: Actor Johnny Galecki visits Build Series to discuss the movie 'Rings' at Build Studio on January 20, 2017 in New York City. (Photo by Mike Pont/WireImage)
LOS ANGELES - JANUARY 25: Sting and Johnny Galecki chat with James Corden during 'The Late Late Show with James Corden,' Tuesday, January 31, 2017 (12:35 PM-1:37 AM ET/PT) On The CBS Television Network. (Photo by Terence Patrick/CBS via Getty Images)
NEW YORK, NY - JANUARY 20: Jim Parsons and Johnny Galecki visits at SiriusXM Studios on January 20, 2017 in New York City. (Photo by Robin Marchant/Getty Images)
The Cast of The Big Bang Theory (actors Kaley Cuoco, Kunal Nayyar, Melissa Rauch, Simon Helberg, Mayim Bialik, Johnny Galecki) pose for a portrait as the winners of 'Favorite Network TV Comedy' at the 2017 People's Choice Awards at the Microsoft Theater on January 18, 2017 in Los Angeles, California. (Photo by Smallz & Raskind/Getty Images Portrait) FAVORITE NETWORK TV COMEDY
NEW YORK, NY - JANUARY 19: Actor Johnny Galecki enters the 'The Late Show With Stephen Colbert' taping at Ed Sullivan Theater on January 19, 2017 in New York City. (Photo by Ray Tamarra/GC Images)
LOS ANGELES, CA - JANUARY 18: Actors Jordana Brewster and Johnny Galecki backstage at the People's Choice Awards 2017 at Microsoft Theater on January 18, 2017 in Los Angeles, California. (Photo by Emma McIntyre/Getty Images for People's Choice Awards)
LOS ANGELES, CA - OCTOBER 15: Actor Johnny Galecki attends Hilarity for Charity's 5th Annual Los Angeles Variety Show: Seth Rogen's Halloween at Hollywood Palladium on October 15, 2016 in Los Angeles, California. (Photo by Randy Shropshire/Getty Images)
LOS ANGELES - NOVEMBER 22: 'The Birthday Synchronicity' -- Pictured: Penny (Kaley Cuoco) and Leonard Hofstadter (Johnny Galecki). Howard and Bernadette welcome their new baby and Sheldon and Amy celebrate Amy's birthday, on THE BIG BANG THEORY, Thursday, Dec. 15 (8:00-8:31 PM, ET/PT) on the CBS Television Network. (Photo by Monty Brinton/CBS via Getty Images)
LOS ANGELES - JANUARY 16: 'The Locomotion Reverberation'-- Pictured: Howard Wolowitz (Simon Helberg) and Leonard Hofstadter (Johnny Galecki). Leonard and Wolowitz try to distract Sheldon when he slows the progress of their guidance system. Also, Penny and Amy take Bernadette out for the night, leaving Raj and Stuart to care for baby Halley, on THE BIG BANG THEORY, Thursday, Feb. 9 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Dean Norris returns as Colonel Williams. (Photo by Sonja Flemming/CBS via Getty Images)
WEST HOLLYWOOD, CA - AUGUST 11: Actor Johnny Galecki, Musician Billy Gibbons and Photographer Timothy White attend the Cars And Stars Exhibit at Morrison Hotel Gallery on August 11, 2016 in West Hollywood, California. (Photo by Liliane Lathan/Getty Images)
LOS ANGELES - APRIL 19: 'The Line Substitution Solution' -- Pictured: Leonard Hofstadter (Johnny Galecki) and Howard Wolowitz (Simon Helberg). Sheldon hires Stuart to spend the day with Amy when he'd rather go to a movie screening. Also, Leonard's mother, Beverly (Christine Baranski), comes to town and Penny struggles to make a connection with her, on THE BIG BANG THEORY, Thursday, May 5 (8:00-8:31, ET/PT) on the CBS Television Network. (Photo by Michael Yarish/CBS via Getty Images)
UNIVERSAL CITY, CA - MAY 26: Johnny Galecki arrives at the Red Nose Day Special on NBC at Alfred Hitchcock Theater at Universal Studios on May 26, 2016 in Universal City, California. (Photo by Jerod Harris/WireImage)
LOS ANGELES, CA - MARCH 28: Johnny Galecki (2L) and Floyd Mayweather Jr. attend a basketball game between the Boston Celtics and the Los Angeles Clippers at Staples Center on March 28, 2016 in Los Angeles, California. (Photo by Noel Vasquez/GC Images)
HOLLYWOOD, CALIFORNIA - MARCH 16: Actors Johnny Galecki and Simon Helberg attend The Paley Center For Media's 33rd Annual PALEYFEST Los Angeles �he Big Bang Theory' at Dolby Theatre on March 16, 2016 in Hollywood, California. (Photo by Matt Winkelmeyer/Getty Images)
AUSTIN, TX - MARCH 13: (L-R) Producer Aaron L. Gilbert and actors Kyle Gallner and Johnny Galecki attend the premiere of 'The Master Cleanse' during the 2016 SXSW Music, Film + Interactive Festival at Alamo Lamar D on March 13, 2016 in Austin, Texas. (Photo by James Goulden Photography/Getty Images for SXSW)
AUSTIN, TX - MARCH 13: (L-R) Actors Johnny Galecki, Kyle Gallner and writer/director Bobby Miller of 'Master Cleanse' are photographed in the Getty Images SXSW Portrait Studio powered by Samsung at the Samsung Studio on March 13, 2016 in Austin, Texas. (Photo by Smallz & Raskind/Getty Images for Samsung)
BEVERLY HILLS, CA - MARCH 09: Actor Johnny Galecki attends the 24th and final 'A Night at Sardi's' to benefit the Alzheimer's Association at The Beverly Hilton Hotel on March 9, 2016 in Beverly Hills, California. (Photo by Vincent Sandoval/WireImage)
BEVERLY HILLS, CA - MARCH 09: Actors Johnny Galecki (L) and Kaley Cuoco attend the 24th and final 'A Night at Sardi's' to benefit the Alzheimer's Association at The Beverly Hilton Hotel on March 9, 2016 in Beverly Hills, California. (Photo by Frederick M. Brown/Getty Images)
LOS ANGELES, CA - MARCH 07: Actor Johnny Galecki attends the premiere of Sony Pictures Classics' 'The Bronze' at the Regent Theater on March 7, 2016 in Los Angeles, California. (Photo by Michael Tullberg/Getty Images)
LOS ANGELES, CA - FEBRUARY 20: Actor Johnny Galecki attends 'The Big Bang Theory' 200th episode celebration at Vibiana on February 20, 2016 in Los Angeles, California. (Photo by Jason LaVeris/FilmMagic)
LOS ANGELES - FEBRUARY 8: 'The Celebration Experimentation' -- After more than nine years together, the gang finally celebrates Sheldon's birthday, surprising him with a special guest, on the 200th episode of THE BIG BANG THEORY, Thursday, Feb. 25 (8:00-8:31 PM, ET/PT) on the CBS Television Network. Seated left to right: Kunal Nayyar, Kaley Cuoco, Adam West, Simon Helberg and Johnny Galecki Standing left to right: Mayim Bialik, Sara Gilbert, Kevin Sussman, Jim Parsons, Melissa Rauch, Wil Wheaton, Christine Baranski and John Ross Bowie (Photo by Monty Brinton/CBS via Getty Images)
LOS ANGELES, CA - JANUARY 30: Actor Johnny Galecki attends the 22nd Annual Screen Actors Guild Awards at The Shrine Auditorium on January 30, 2016 in Los Angeles, California. (Photo by Dan MacMedan/WireImage)
Actor Johnny Galecki attends the I Know What You Did Last Summer Hollywood Premiere on October 8, 1997 at GCC Galaxy Theatre in Hollywood, California. (Photo by Ron Galella, Ltd./WireImage)
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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.

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