In this week’s The Big Bang Theory “The Proton Transmogrification,” Raj, Sheldon, and Leonard explain to Penny that May the 4th is “Star Wars Day” because it sounds like “may the force,” part of a famous Star Wars line. Penny is not amused.

Sheldon goes over his Star Wars day schedule, and comes to the conclusion that the hour of complaining he allotted for himself may not be enough time. Leonard interrupts and tells Sheldon that Arthur Jeffries, known as Professor Proton, has passed away and the funeral is on Star Wars Day. Sheldon seems to be more upset about his day being interrupted than he is about the death.

Amy doesn’t understand why it is more important to watch “goofy space movies” than to go to the funeral. Sheldon snaps back saying that if they were in a physical relationship, that remark would have lost her sex. Sheldon feels like since Arthur is gone, there is nothing to do about it and he doesn’t need to go.

Amy believes that Sheldon is more upset than he is letting on. She and Bernadette decide to make the guys a Death Star cake. This goes wrong when the spherical shaped cake rolls off the table.

At the funeral, Penny admits to Leonard that she has never been to a funeral before. She is very upset and feels like she wants to cry but can’t, so she tells Leonard to cry instead. Leonard doesn’t show his emotions until he starts talking about how much Arthur meant to him. This makes Penny start to cry as well.

Sheldon, Raj, and Howard prepare to start their Star Wars movie marathon. Sheldon overreacts and runs off when the group wants to skip The Phantom Menace and he does not.

Sheldon sees Arthur in his sleep, who tells him that being dead is great since he doesn’t have to run to the bathroom all the time. He also expresses his disappointment that he isn’t haunting his ex-wife. Sheldon tells Arthur that he is like his “Obi-Wan,” believing that he has come to be his mentor. Sheldon then imagines Arthur in a Jedi robe with a lightsaber.

The funeral makes Leonard think about things he would regret not doing. One of those things would be not accepting Penny’s marriage proposal. She tells him that it wasn’t the right time and that him proposing at the funeral wouldn’t be the right time either. Leonard points out that he has proposed twice and Penny only once. To even it out and make Leonard happy, Penny agrees to proposes again so Leonard can reject her. He doesn’t make this easy, as he teases her about accepting the whole way home.

Amy and Bernadette, still working on the Death Star cake, talk about how they first got into science. Bernadette wanted to figure out a way to make herself taller, while Amy found a biology book in the library while researching what whores do.

Sheldon thinks he is seeing Arthur to help him get over his passing. When Arthur asks Sheldon if this is the first time he lost someone Sheldon replies that he has gone through 11 “Doctor Who’s.” Although, he does feels like every man he has looked up to, his father, grandfather and now Arthur have “gone away.” Arthur tells Sheldon that he needs to appreciate the people around him while they are still there.

When Leonard goes into Sheldon’s room to see him, Sheldon gives him a big hug. Sheldon then gets up to tell Raj and Howard they have to start the marathon from the beginning even though they already watched the first five.

Amy and Bernadette bring over the Death Star cake and say they are sorry that they had to miss the movies. Howard excitedly tells them that they didn’t miss anything since they just started over. This prompts Bernadette to whisper an expletive.

Arthur appears to Sheldon again, telling him that apparently he is there whenever he needs them. Sheldon is happy about this, but Arthur isn’t as thrilled. Arthur points out that perhaps Sheldon should do something better with his limited time than sleeping during Star Wars. Sheldon doesn’t see his point.