The Proton Resurgence

"The  Proton Resurgence   is the twenty-second episode of the sixth season of The Big Bang Theory. The episode will air in April 18, 2013.

Summary
Leonard is teaching Penny to launch a toy rocket using his computer, while Sheldon discovers that Professor Proton, the Mr. Wizard of his youth, is available to perform at children's birthday parties. Raj asks Howard and Bernadette to watch his dog over the weekend while he spends time in the telescope lab. Later, Raj brings his overly pampered dog to their apartment and Howard sympathized with her having a psychotic mother. Sheldon can't get to sleep due to Professor Proton's visit the next day and also keeps Leonard up. After  Howard and Bernadette are return from the park with Raj's dog, Bernadette is feeling what it's like to have a family and suggests that maybe they should have a baby. Then they panic when the dog has can't be found. Sheldon is pacing because Professor Proton is late. He is stuck on the stairs having to walk up three flights and is confused when he learns that there is no children's birthday party.