The Big Bang Theory [05/01/14] "The Proton Transmogrification"

I thought this was a good episode. However, I can't believe they killed Dr. Proton. Jim Parsons and Bob Newhart interacted so well together. I don't see them bringing Newhart back as Obi Wan Proton. I know Newhart was only on a couple of times, but they were all so good.