Which long-running TV series featured the character "Professor Proton"?

Professor Proton (real name Arthur Jeffries), portrayed by the actor Bob Newhart, was a recurring character on the iconic TV series, "The Big Bang Theory". He presented a TV show that two of the main characters, Sheldon and Leonard, were obsessed with when they were children. He had a puppet sidekick with the lovely name of Gino the Neutrino!

Sheldon and Leonard are ecstatic to discover that Professor Proton still functions as an entertainer, and hire him, apparently oblivious to the fact that his shows are not aimed at grown men who are now scientists in their own right!

Still, he maintains a relationship with them, especially with Sheldon, who continues to look to him as a mentor. There is a touching scene when Professor Proton is seriously ill and Sheldon sings the lullaby "Soft Kitty" that his beloved grandmother used to sing to him.

Sheldon is genuinely devastated when Professor Proton passes away, although, as ever, he struggles to show his emotions and to cope with them.

However, he continues to appear to Sheldon as a ghost (or, as he insists, a projection of his own inner thought processes) and encourages him to go through with his intention of finally sleeping with his girlfriend (and later wife) Amy on Amy's birthday.