Comedy legend Bob Newhart makes his debut on The Big Bang Theory on Thursday (May 2, 2013) with a role that has been a long-time coming for both Newhart and producer Chuck Lorre. The co-creator of the CBS show has been constantly hounding the six-time Emmy nominee for roles on his shows, and Newhart finally agreed on 'Big Bang' - on two conditions.

"I had only two things that were paramount: No. 1, my scenes had to be taped live. There's a tendency to pre-tape a lot of stuff and put a laugh track on it and you lose something," he told the Hollywood Reporter, "No. 2, I wanted it to be a semi-recurring role. He was fine with both and later called me with the story of Professor Proton." Newhart's character is an influential man from Leonard (Johnny Galecki) and Sheldon's (Jim Parsons) childhood.

The Big Bang Theory's ratings continue to grow - something rare in the U.S. television world - but Newhart thinks he knows why the show's reruns are beating top show such as American Idol. "It's beautifully cast, has great writing and it's intelligent," he said, "There was a longing for something intelligent -- to credit the audience being intelligent. It doesn't talk down to the audience at all.

The Big Bang Theory, featuring Bob Newhart as Professor Proton, hits screens on Thursday at 8pm on CBS.

Chuck LorreChuck Lorre Managed To Pursuade Bob Newhart To Join The Big Bang Theory