Sheldon and Leonard tried to reach the stars, while the rest of the gang learned the limits of the TARDIS on The Big Bang Theory season 8, episode 19.
Far, far away
Sheldon and Leonard drive to UC Berkley, where they are giving a speech about their paper. Sheldon is in such a good mood that he lets Leonard play music in the car until things get metaphysical.
The guys are ahead of schedule, so Sheldon proposes they visit George Lucas’s Skywalker Ranch. The Ranch turns out to be ordinary and lacking in mystery, but Sheldon and Leonard are thrilled to be there. Sheldon wants to go in, so Leonard rings the bell. Their embarrassing pitch to be let inside goes unnoticed thanks to a broken speaker, and the guys are allowed to drive into Skywalker Ranch.
Party-trooper
Next up: The security guard. Against Sheldon’s advice, Leonard admits that they are just hopeful fans. The guard won’t let them in, but offers them a few souvenirs. Unsatisfied, Sheldon leaves the car and races toward the Ranch; he nearly makes it before he is chased down and tasered.
Leonard and Sheldon fret in the security station with another overzealous fan. The guard lets them off with a warning, but they can never come back to Skywalker Ranch.
Sheldon and Leonard return home. Leonard is weary and upset, but Sheldon convinces Leonard to look on the bright side: They did get into Skywalker Ranch, and have an adventure.
A dual for the ages
Howard and Bernadette are moving into Mrs. Wolowitz’s house, and are selling some of her things. Amy, Penny, and Raj help clean out the house, which mostly involves playing ping-pong.
Bernadette wants to sell Howard’s massive Doctor Who TARDIS, but Howard objects. (Deciding to compromise and just keep the thing in the garage appears not to occur to them.) Raj proposes playing ping-pong to decide whether or not they keep it; he represents Howard, while Penny plays for Bernadette.
The Master
Raj is beating Penny until Bernadette suggests that Raj can take the TARDIS to his apartment. Amy takes over for Raj, who now plays for Bernadette and possession of the TARDIS. Raj can’t hit Amy’s serve, but Amy can’t hit anything Raj sends at her.
At the match point, Bernadette plays her trump card: How excited might Sheldon be if the TARDIS wound up in Amy’s apartment?
That settles things, and the TARDIS is installed outside Amy’s bedroom. “If this doesn’t get Sheldon into your bed,” Bernadette gleefully promises, “Nothing will!”
And Sheldon is thrilled by the TARDIS in Amy’s room… but unfortunately, he is much too excited playing Doctor to explore anything else with Amy.