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The Entire Big Bang Theory Story Finally Explained

The Big Bang Theory is one of the most interesting case studies of snobbery versus mass popularity this century. One one hand, the show became an online punching bag for people to signify that their taste in television was more complex than the average viewer. On the other, it was frequently the highest-rated show on television, ran for 12 seasons, and won 10 Emmys.

The show's harshest critics were wrong. The Big Bang Theory had the misfortune of being an incredibly successful iteration of the tried and true multi-cam sitcom format in a time when Peak TV and innovations in the sitcom form, seen in shows like The Office and Parks & Rec, made some viewers expect more from their 22 minutes. Across its 12 years, The Big Bang Theory never lost sight of what it was, or caved to those outside pressures. It remained, to the very end, a well-oiled machine crafted to deliver jokes about pop culture, relationships and obsessive nerdery. The show knew what it was and it did that very, very well.

Of course, if there was literally no growth across the years, fans would tune out. Similar to its long-running forebears in the sitcom space, the core cast grew and changed (albeit at a slower pace than they would in the real world), providing fans with a satisfying story arc that closed out in 2019.While TBBT never made the story hard to follow, an overview can be helpful. That's why we're running down the story of Leonard, Howard, Raj, Penny and Sheldon for anyone who just wants to take the leap into a random batch of syndicated episodes.

The whole universe

The story of The Big Bang Theory takes place in Pasadena, almost entirely confined to a few apartments. It centers around the misadventures of physicists Leonard Hofstadter and Sheldon Cooper, branching out from these co-workers and roommates to include their fellow Caltech scientists, neighbors in their building and romantic partners. Cooper is a theoretical genius who has trouble grounding himself in the real world. At the beginning of the series, he holds an incredibly condescending view of non-scientists and believes himself to be an unparalleled intellect.

Hofstader has a much kinder view of the world. However, both of them have trouble interacting with neurotypical people, particularly women. Throughout the series, partners and friends bring Hofstader, Cooper and their friends astrophysicist Raj Koothrappali and engineer Howard Wolowitz out of their respective shells. The catalyst for this introduction to the outside world is Penny, the boys' neighbor who lives across the hall in their apartment building. The aspiring actress and waitress makes friends easily, and her proximity to the scientists helps to drag them out of their cloistered and academic existence.

A hot, dense state

The series starts with Sheldon and Leonard already co-habitating. Several seasons of the roommates butting heads pass before they explain how the odd couple came to live together. Cooper is frequently a tyrant, stubbornly refusing to adjust his routine or consider the feelings of others. This leads to frequent fights where Hofstader seeks refuge across the hall in Penny's apartment. After one particularly nasty fight over the thermostat settings, Leonard finally explains how he ended up in the apartment with Sheldon, noting Cooper has grown significantly as a person since they began living together in 2003.

In the season 3 episode "The Staircase Implementation," Leonard reveals why he feels bound to Cooper and in the process, reveals what Cooper was like prior to their agreement to live together. In the flashback, Hofstader is shown seeking a roommate after first coming to work at Caltech. He goes to view his current apartment and is blocked at the door by Cooper, who quizzes him on sci-fi trivia, preferences of different iterations of famous characters and other scientific knowledge questions before allowing Leonard to enter.

The apartment at this point, in contrast to its later coziness, features a spare living room that indicates an otherwise occupied mind. Instead of the couches and chairs that the main characters spend the majority of their time gathered on, the layout is simply lawn chairs around a card table.

When he enters his future bedroom, he sees that the former roomie has painted "Die Sheldon Die" as a parting gift. Undeterred and in need of a room, Leonard decides to stay. He gets an early glimpse of Cooper's temperament when he's forced to sign an incredibly detailed roommate agreement that will be used to arbitrate many future disputes.

Why he stayed

This leads Penny to ask the obvious question: why are you still living with him? Leonard demonstrates the many ways that Sheldon is valuable as a friend. In spite of his seemingly cold and caustic demeanor, Cooper has frequently defended Leonard from potentially harmful situations.

He shares that Cooper ran off Leonard's then-girlfriend Joyce Kim. After their relationship ended, Cooper and Hofstader discovered that Kim was a spy attempting to get information about an experimental rocket fuel that Hofstader was developing. Leonard easily could have been accused of collaboration with his ex, a North Korean agent. A criminal charge of treason was hanging over Leonard's head. However, Sheldon promised to defend Leonard should the government come looking.

Additionally, Hofstader's enthusiasm for his rocket fuel experiments was nearly deadly. Egged on by his engineer friend Howard Wolowitz and the astrophysicist Raj Koothrappali, they attempted to use his fuel in a rocket that Wolowitz built. Leonard got the proportions wrong, and created an unintentional bomb. Cooper's advanced mathematical mind correctly calculated how long they had before the fuel detonated. He pushed a panicking Hofstader away from the mixture, placed it in the building's elevator, and closed the door right before it exploded, unquestionably saving Leonard's life.

He promised to keep mum about the cause of the destroyed elevator, which remained broken for almost the entire series. His ability to protect his friends and the multiple times that he kept Leonard from serious harm show Cooper's value as a roommate.

Drawing them out

Leonard, Sheldon, Howard and Raj are all sheltered nerds who have trouble deviating from their incredibly regimented schedules. They have divided their week into visits to the comic book store, gaming nights and television viewing parties.

The forces that eventually break this up are all romantic interests. Over the course of the series, Hofstader's life is shaken by an on-again, off-again relationship with their neighbor Penny. The perverted and oddly dressed Howard is reeled in and reformed by his eventual wife Bernadette Wolowitz. The two toughest nuts to crack are Raj and Sheldon.

Raj is clinically terrified of the opposite sex. His phobia is so intense that, even though he desperately wants to be in a relationship, he loses the ability to speak in the presence of any woman. He's eventually able to get over this intense fear after he dates a sadistic dermatologist named Emily Sweeney. (The reference to the demon barber is intentional, as she is shown to love cutting into people and watching gore.)

As with all other aspects of the show, Sheldon is the most difficult to budge. His changes in character are gradual and hard-won, but they come thanks to the efforts of Amy Farrah Fowler. Fowler is remarkably similar to Cooper, and probably the only person in the world of the show who can fully understand his worldview. She avoided romantic relationships her entire life to better dedicate herself to work in neurobiology. Sheldon did the same, but Amy differs from him in desiring a partner.

She turns her relentless planning energy and desire for a regimented schedule on the concept of marriage, a five-year plan to pull Cooper out of his own head so that they can marry.

Will they, won't they?

Sitcoms of The Big Bang Theory's ilk depend on familiarity and a slow sense of growth as viewers come to love the characters. The show did this incredibly well, pulling out many of the timeworn tropes of television comedy across its 12 seasons. The early romantic tension in the series comes from Leonard and Penny, who seem to be consistently on the verge of a relationship. Once they do pair up, the ups and downs of their relationship (and the way that the street-smart Penny fit into the dynamic of the scientists' insular friendship) carry the series forward.

The relationship builds, explodes and recombines throughout the show's run with Penny teaching the crew how to exist outside their bubble. The couple fall apart in the fourth season, and the series' 100th episode centers on Leonard's belief that they should be together. After imagining a "second first date" with Penny that ends with them falling into typical squabbling, he still realizes he cares enough for Penny to pursue a relationship.

They nearly break up again while traveling to Las Vegas at the tail end of the eighth season. Leonard and Penny make an impulsive decision to get married and see it through even after Leonard admits that he kissed a coworker.

Rather than wrap the season with their wedding in typical sitcom fashion, the ninth season begins with their marriage and explores the hard work of keeping it together as they deal with Leonard's admitted infidelity. They end the season planning a wedding do-over with family and friends. Wedding II starts off season 10 and the couple end the series together.

Two weddings

Sheldon Cooper's callous attitude toward Amy Farrah Fowler's feelings leads the couple to split and reconcile throughout the series. They go on their first date in the premiere episode of season 4 and are not married until the finale of Season 11, after Sheldon finally realizes that there is no one else on Earth he could see spending the rest of his life with. Given the unconventional nature of their relationship and their extreme personalities, the show opts not to end with a romantic milestone for them, instead focusing on their work together in the sciences.

Howard Wolowitz grows more than perhaps any other character throughout the series. He starts the show as an unrelenting creep whose off-putting perversions sabotage any attempt at a relationship. And this is true even of his relationship with his eventual wife Bernadette. She breaks up with him in season 4 after finding out that he had cybersex with fellow World of Warcraft players. Bernadette and Howard reconcile, however, and she is able to pull him out from under the thumb of his mother and help him become his own man. The pair have children together throughout the series and both realize their professional goals, with Wolowitz traveling to space and Bernardette receiving a PhD in microbiology, going into the private sector and supporting their family.

Penny's growth

Throughout the series, Penny grounds the rest of the cast of characters. Most of the women of the show are brought into the series via their connections to Penny and it's her frequent lessons in the real world that help the men become fully functioning adults.

Along with the men, Penny settles into a comfortable adulthood. She follows her friend Bernadette into the world of pharmaceuticals, leaving behind her precarious life as a waitress and aspiring actress for the solidly middle-class existence of a sales representative. The possibility of Penny becoming a mother bookends the series, as she is shown in the origin episodes fretting over a pregnancy test. Ultimately that initial test was negative, which greatly relieved a young Penny.

The accumulated changes in Penny's life and her much more stable existence are reflected in the way she reacts to a similar situation at the very end of the series.

The finale, explained

The Big Bang Theory closes with quite a few endings and at least one beginning. Leonard and Penny finish the show celebrating a positive pregnancy test, with the couple ecstatic at the idea of being parents.

Raj's romantic life is left up in the air, but it's implied that he might go from someone who couldn't even speak in the presence of women at the show's start to dating a world-famous actress. Howard and Bernadette have been living in wedded bliss for a while, so the series just lets them be.

Amy and Sheldon achieve their lifelong goal of a Nobel Prize in physics, highlighting the way that it's always been about the work for them. However, after every character in the series finally explodes at Sheldon for his domineering manner and incredible stubbornness, Cooper delivers the most shocking moment of the finale by realizing that there's more to the world than himself.

From the ceremony stage, he thanks his friends for their incredible patience.

"I was under a misapprehension that my accomplishments were mine alone," he says after tossing a characteristically wordy speech. "Nothing could be further from the truth. I have been encouraged, sustained, inspired, and tolerated not only by my wife, but by the greatest group of friends anyone ever had."

Further viewing

Though The Big Bang Theory is over, fans shouldn't fret. CBS continued turning to Sheldon Cooper to mine ratings gold, diving into the early life of the character as a child prodigy in the series Young Sheldon. The series shows every indication of turning into a long-running hit like its predecessor, pulling in average ratings of well over 12 million households per episode.

For a glimpse into the way the show was made, and the genuine love the actors who make up the cast seem to have for one another, there's the documentary Unraveling The Mystery, a behind-the-scenes feature that premiered after The Big Bang Theory's run ended. Hosted by Johnny Galecki (Leonard) and Kaley Cuoco (Penny), the heartfelt doc features clips from the series, reflections on particularly beloved moments and a look at how the sitcom sausage was made for 12 seasons.

Of course, the series itself provides plenty of material on its own to devour. And its traditional sitcom structure means that episodes can be watched at random any time the itch strikes.

A note on Raj

Raj is the character in the series that's given the least to do. Given the way the show builds characters through relationships, his perennially single status leaves him nowhere near as much room to change as the other characters. That doesn't mean he's entirely static, though. 

Raj suffers from selective mutism for most of the series. When he gets near women, he loses the ability to speak due to overwhelming anxiety. Throughout the show, we learn that this mutism goes away if Raj is drunk (or believes himself to be drunk). He is eventually cured of his mutism after going through a relationship with an equally anxious woman named Lucy.

Because of his style of dress, love of women-targeted entertainment and constant companionship with Howard Wolowitz, he is occasionally assumed to be gay. Counter-intuitively, he's typically more successful with women than his best friend Wolowitz, as Howard's aggressive and perverted manner is off-putting. Until Howard eventually settles down with Bernadette, Raj is shown to win women over more frequently via his uncomfortable silence. 

Raj was very nearly married in later seasons, falling into a relationship with a woman named Anu. That storyline came to an end when Anu was offered a job in London and Raj opted to stay behind in Los Angeles. 

By no means a sure thing

Leonard and Penny are the relationship through which all others are introduced, but their own happiness was not a foregone conclusion. The other characters are all extremes, suffering from wild maladies and character tics that make their relationships cartoonish. Leonard and Penny, in contrast, act as a sort of audience surrogate. They react to the oddness of their friends as we would and they struggle with relatively grounded relationship problems like fear of commitment and infidelity. 

Across many seasons, the pair separate and reunite as they each prove to be imperfect partners. Penny's deep fear of commitment butts up against Leonard's desire to be married several times, with Leonard eventually telling Penny that he'll be ready to propose to her once she gives the green light. In between this moment and their actual wedding, Penny proposes to Leonard while incredibly drunk. Though Leonard wants nothing more than to be married to Penny, he turns her down, knowing that she's not in her right mind. 

This decision proves to be the correct one, as Leonard and Penny end the series as one of three happily married couples, with both of their careers on an upward trajectory.