“I had only two things that were paramount: No. 1, my scenes had to be taped live,” the comedian recalled in a 2013 interview. He explained: “There’s a tendency to pre-tape a lot of stuff and put a laugh track on it and you lose something. With ‘Newhart,’ ‘Lucy,’ ‘Honeymooners,’ ‘Mary Tyler Moore,’ and ‘All in the Family’ it was always done in front of live audience.” It’s a point that’s tough to argue with, as Newhart name dropped some of the best sitcoms of all time. He also admitted that his own performance is fueled by the experience of working in front of a crowd. “I always felt that the live audience gives it adrenaline,” he told THR. “That’s the only way I function.”

Luckily, “The Big Bang Theory” was one of a handful of shows still working with live studio audiences in the 2010s, making Newhart’s request easy to accommodate. The actor’s second request was that Professor Proton become a “semi-recurring role.” While Newhart didn’t clarify whether he was worried about appearing in too many episodes or not enough, he said that Lorre agreed, and called him up with the idea for his character soon after. The pair had actually known each other for years before the inception of Professor Proton, with Newhart saying he was “familiar with [Lorre’s] work­­ going back to ‘Roseanne’ and ‘Cybil.’ In fact, the pair apparently knew each other from days spent on the studio lot when “The Bob Newhart Show” was filming.