This article is about the episode: If you are looking for the piece-of-shit TV series of the same name, click here.The Big Bang Theory is an episode of Family Guy.
Stewie and Brian go back in time to stop Bertram from killing Leonardo da Vinci in order to erase Stewie from the universe.
After Lois leaves, Stewie tell Brian about wanted to order an item from a magazine. Brian insults Stewie by saying he would order the guy on the cover of the magazine. Stewie comes up with a terrible return insult, that causes Brian and Chris to mock him. Stewie plans to go back in time to top his insult Brian, which he does and succeeds. Stewie plans to go back in time to embarrass Brian again. He travels back to "The Courtship of Stewie's Father", when Brian is going to sing, "Peanut Butter Jelly Time", but Stewie steals his banana suit and sings to Peter, which cheers him up. Stewie later plans to mess with his former date with a Victoria's Secret model, which Brian finds out about and plans to stop. Brian and Stewie begin to fight for control over the machine, accidentally launching them outside the space-time continuum, where the laws of physics don't apply and where the Return Pad can't get them home. Stewie tells Brian that he can overload his Return Pad which would cause an explosion that would send them to the future. Stewie is reluctant, but Brian talks him into it by saying he would laugh at a joke that he would never tell to Stewie, unless he tried. Stewie did it and went back to the future. After research, Stewie finds out that his explosion was the Big Bang and that he created the universe.
Stewie goes to a market, where a terrorist works, that sells him plutonium. Bertram, Stewie's half-brother, witnesses this and decides to use Stewie's time machine to his advantage and sneaks into Stewie's house, causing Stewie to wake up. He distracts Stewie by giving him a play lawnmower. Bertram goes back in time, when Brian goes into Stewie's room. Afterwards, time ripples start erasing everything. Taking cover in the time machine, Stewie realizes that Bertram must have gone back in time and prevented Stewie from being born. Because he wasn't born, he wouldn't be able to start the Big Bang, causing a paradox that threatens to erase everything from existence. In order to stop Bertram, Brian and Stewie go back in time to to fifteen minutes before he arrives in the past.
They arrive somewhere in the late 1400s or the early 1500s, Venice, Italy. Stewie finds out that Leonardo da Vinci is his ancestor. He guesses that since he and Bertram share DNA from Peter, he must've come back this far to eliminate Stewie without affecting his own existence. Once Bertram arrives, he throws a knife at Leonardo, causing Stewie to jump in front of it with a palette blocking it. They end up stealing his early flight inventions and fight in midair. Stewie ends of deflecting a missile and blowing Bertram's glider apart. When he regroups with Brian and da Vinci on the ground, Bertram has them all at crossbow point. Though warned that he could destroy the universe, Bertram doesn't care and kills Leonardo da Vinci, causing Stewie to fight Bertram. Bertram knocks Stewie down, but he grabs the crossbow and shoots Bertram in the chest and the head, killing him.
Brian then laments their failure, before noticing that universe hasn't ceased to exist. Stewie realizes that there must be a slim chance of himself being born. When Bertram voids his bowels, Stewie gets the idea to become his own ancestor by injecting his DNA into Leonardo's girlfriend. He sends Brian to the future to see if his plan works, where a priest from the Vatican comes to deliver Brian a letter written by Stewie, under the alias Leonardo da Vinci. Stewie cryogenically froze himself under their basement. Brian then dug Stewie up, and Stewie attempts to trick Brian into kissing him, which backfires when Brian offers to get Meg. As a gift, Stewie gives Brian a candle from that time period which goes unappreciated.
- Bertram makes his third and final appearance in this episode, as he is irreversibly killed and the timeline with him in it is vanquished from existence.
- Stewie's homosexuality is suggested twice in this episode. After flying past the statue of David he comes back for a second look at the penis, and when he wakes up in present-day Quahog he tells Brian to kiss him to wake him up.
- Astrophysicist Neil DeGrasse Tyson, who would later host the Seth MacFarlane-produced revival of Cosmos, is credited as the Scientific Consultant for this episode.
- The episode title is a reference to the scientific theory of the same name.
- Stewie mentions that he got to stay up late until 7:30pm to watch Phineas and Ferb. Phineas and Ferb was created by former Family Guy director Dan Povenmire.
- The priest delivering the letter is a reference to Back to the Future Part II, when Marty McFly receives a letter from a Western Union courier, sent by Dr. Emmett Brown 70 years earlier.