Sheldon and Leonard hire Professor Proton, the host of their favorite childhood TV show, to perform, on THE BIG BANG THEORY, Thursday, May 2nd on the CBS Television Network. Bob Newhart guest stars as Professor Proton. Behind the Scenes Photo. Pictured left to right: Jim Parsons, Kaley Cuoco, Bob Newhart and Johnny Galecki Photo: Michael Yarish/Warner Bros. ©2013 Warner Bros. Television. All Rights Reserved.