Bob Newhart and Chuck Lorre had wanted to work together for years, and "The Big Bang Theory" provided the perfect opportunity. Newhart agreed to be on the show under two conditions: his scenes had to be taped in front of a live audience, and he wanted a recurring role. He became one of the best guest stars on the show, even after his character, Professor Proton, passed away. Jim Parsons, who played Sheldon, was initially unsure about the character's death, but ultimately appreciated how it was handled. Newhart enjoyed his time on the series and praised the cast and writing. Despite changing sitcom dynamics, the show was a success because it didn't talk down to the audience.