Trama

Sheldon kicks Amy out of the apartment to work solo, and she and Leonard end up bonding during a series of science experiments; Howard is replaced by Bert in Footprints on the Moon.

In Raj, Amy and Leonard celebrating some professional successes however small, it comes to light that Sheldon is currently working on nothing, which is bothering him. As such, Amy encourages him to focus his attentions on finding a new scientific project to work on. In Sheldon wanting some solitude to focus his attention, Amy takes refuge at Leonard and Penny's. Leonard and Amy bond when they learn that they both were spelling bee champs at school. So they decide to recreate together science projects from their youth. Leonard and Amy's time together leaves Penny to find something else to preoccupy herself in her lack of interest in what Leonard and Amy are doing. Across the hall, the solitude is only magnifying Sheldon's frustration in not having any idea what he wants to do. He may get some inspiration from the most unlikely of sources. Meanwhile, Footprints on the Moon, Howard and Raj's band, has an upcoming gig at a bar mitzvah. Their rehearsing is causing problems at the Wolowitz/Rostenkowski home, both in the noise and Bernadette needing Howard to take care of Halley. This situation leads to Howard suggesting to Raj that he find another band mate to take his place so that he can focus his time on helping Bernadette take care of Halley. While Raj goes on his search for Howard's replacement, Howard manages to find something else to do with his time that has nothing to do with Halley.—Huggo

While the gang is having dinner in Leonard and Penny's place, Raj walks in triumphant with copies of that day's newspapers. Leonard accuses him of slipping back into the 1990s. Raj tells them that the paper reviewed his planetarium show, though it was just in the column under things to do that weekend. Penny just makes a boat that she turns into a hat. Amy adds that her and Howard's project has been written up in a journal. Leonard and Bert are also making progress on their meteorite project. Sheldon gets defensive and asks what he was working on.

Returning to their apartment, Amy wants to know what is going on. Sheldon was upset that he was currently not working on anything. Amy suggests that he take time and try to refocus and find something that excites him. He replies that he doesn't know what he would do without her, and then he kicks her out of the apartment to work.

Amy enters apartment 4A asking if she could hang out since Sheldon wants some alone time to work. She is offered to watch TV with them, but first she has to medicate her sinuses which disgusts them.

Howard and Raj are getting ready to have band practice. They start playing "Sherlock Around the Clock", when Bernadette calls down and tells them to keep the noise down. Starting to play quieter, they still wake up Halley and Howard is told to go get some fresh diapers by his wife. He still motions to Raj that he thought they were rocking.

Sheldon is getting organized to work when the telephone rings, greatly disturbing him. It's his mother Mary (Laurie Metcalf) who wants him to guess who she met at the barbecue festival. Sheldon complains that he is busy, she retorts as to why he answered the phone. Sheldon tries to start working at his whiteboard with no results so he calls his mother back. She tells him who she met, he thinks about his work for a minute and then calls her back and starts to discuss the gentleman she met.

The next day Raj is having lunch with Leonard who had fun with Amy when he found out that she was also a spelling bee champ. They tried to stump each other causing Penny to go to bed at only nine o'clock. Howard shows up and Raj asks him about band practice. He is awfully busy taking Halley over to Bernadette's folks. Raj is thinking about canceling the Bar Mitzvah gig. Howard doesn't want to break up the band, but he thinks Raj should find someone else. Raj jumps up quickly to go ask Bert who plays the guitar.

Penny returns home and finds Amy and Leonard reenacting a science fair experiment they both did in the ninth grade. Penny remembers getting included in a science project by showing Jenny Runyon how to flirt with guys. Penny got an "A" and Jenny got pregnant. Next they decide to build a cobra wave like they did in the seventh grade. Amy wonders if they should watch that show she likes where people who want to buy a house, then do that. Instead, Penny goes to get dinner.

Sheldon is excited about completing some equations so he calls his mother and tells her that the odds of him running into Mr. Watkins was one in eighteen million. Mary has bad news that he passed away this morning and wonders out loud what the odds of that are. Sheldon goes to figure it out.

Penny returns with a pizza, hears how excited Leonard and Amy are constructing their wave and goes to she knocks on Sheldon's door. She claims to have brought him dinner, to find Sheldon is not really working since he is drawing parallelograms and listing types of disasters. He wants to find a new approach to dark matter, but keeps getting interrupted. Sheldon asks Penny to sit down and not say anything. She starts mocking him in sign language.

Raj and Bert and getting ready to practice at Raj's apartment. Bert tells Raj about his boulder song about the boulder that chases Indiana Jones. Raj likes the idea and Bert plays his geology song. "Six tons of granite and some Micaceous schist."

Amy and Leonard have built a wave front out of Popsicle sticks and want to predict its wave height. Amy feels it's like being back in preschool. She also asks Leonard whether being married feels any different. No. It was the answer Amy was hoping for since she and Sheldon are in a real great place now. She doesn't want to mess it up. Leonard reminds her that he did kick her out. Amy explains that his work is really important to him and she finds that really sexy. That and...Leonard doesn't want to know as he sets off the Popsicle sticks. It's Sheldon's butt.

Sheldon is describing to Penny his next dark matter approach which he finds too pedestrian. Penny agrees and wonders about the cheese in the pizza crust. Penny then tries to get him to think about what excited him about dark matter. Penny describes it as a rebound science that he goes after to make himself still feel pretty. Sheldon still has not forgotten the wonder and simplicity of string theory. He begins to describe it to Penny who tries to understand it.

Back in Bernadette's bed, she can't sleep because Howard, without his band, is trying to write an astronaut musical. Bernadette thought his time was going to be spent helping her with the new baby. Howard starts to play the opening song as Bernie looks at him like he is crazy. Bernie sends him back to his band with Raj.

Back in string theory, Penny describes string theory like a guitar string that vibrates which each vibration is a different sub-atomic particle. Penny wonders if they just figured out string theory, but it was not just one night's project scoffs at Sheldon. Science has been working on it for decades which baffles Penny since it is only a string. String can be straight, in loops, and get tied up in knots. Sheldon explains that there are no knots in more than four dimensions; unless one considers them as sheets. Sheldon starts with a new idea which has a lot of possibilities. Penny quips that that only took her a minute.

Penny returns home and tells them that she stopped at Sheldon and helped him solve string theory. "What?" asks Amy. She tells them that the answer is knots. Leonard mentions that there are no knots in more than four dimensions. Penny tells him that he should consider the knots as sheets and then says good night. Both Amy and Leonard wonder what was happening.

Finally "Footprints on the Moon" is playing at Toby's Bar Mitzvah. Raj says that he will experience many obstacles in life. "Some that feel like boulders", adds Bert. Cue his Indiana Jones boulder song.

Title reference: A triple Entendre to represent Sheldon going into isolation to figure out his future research field only to go back to studying string theory, the vibration of the strings in string theory, and Howard's oscillation between being in a band with Raj and being solo.