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"The Monopolar Expedition" is the twenty-third episode and the season finale of the second season of the American sitcom The Big Bang Theory. This episode first aired on Monday, May 11, 2009.


The guys are going to the North Pole to assist Sheldon looking for data to prove String Theory making both Penny and Leonard upset about being apart for three months.

Extended Plot[]

Leonard is working on his whiteboard trying to find an error that Sheldon insists is there, but will not help him with. As suddenly as bazinga, Leonard finds out that he has fallen for one of Sheldon's classic pranks. Sheldon finds out that Caltech President Siebert wants to meet with him at eight o'clock tomorrow morning, which gives Sheldon eighteen hours to think about it.

Early the next morning Sheldon is knocking on Leonard's door to tell him about his uninvited visit to the president's house. His grant from the National Science Foundation to go the magnetic North Pole to look for evidence of slow moving monopoles (in order to validate string theory) has been approved. Leonard perked up that the president offered to send him north. Sheldon replied, "In fact, he was quite enthusiastic. He said "quite frankly, if I could send you tonight, I would." Sheldon's interest in going is incredible since he has to leave the movie theater if he gets a brain freeze from his Icee.

Leonard, Raj, and Howard are excited about being Sheldon-free for three months and all the small victories they will have like sitting in his spot. On the contrary, Sheldon proposes that they accompany him as his support staff for the project. At first they decline to spend three months in a hut with an "anal nut bag," as Howard puts it, but the idea begins to grow on Leonard and Raj since if Sheldon is successful it would mean a massive boost to their careers. Howard is concerned that being put in a situation like that would make him snap and cause him to become "the engineer who builds the crossbow that kills Sheldon". Finally they decide to go along to be part of the team that make such paradigm shifting discoveries. Raj figures that due to his suffering it will result in a karmic payback of becoming a "well-hung billionaire with wings" in the next life. Howard agrees to go due to peer pressure.

The Monopolar Expedition 16

It means I wish you weren't going.

Sometime later, Sheldon goes over to ask Penny a favor by knocking on her door. Before he can perform his second set of knocks, Penny echoes him with “Knock..knock..knock...Sheldon”. A competition starts as they start going faster and faster. (Penny..Sheldon..Penny..Sheldon). A very stressed out Sheldon then asks if he can have access to the Cheesecake Factory freezer. Penny reminds him that she had already told him that the freezer is cold enough and safe enough to keep his hamburger fresh. He really wants to borrow it so they may practice acclimating themselves to the cold for their expedition to the North Pole for three months. Penny is surprised and goes to confront Leonard asking why he hadn't told her. Leonard explains that they were spending their time getting physicals, buying thermal underwear and studying snow. Penny declares that it is no big deal and that she'll check on the ice box thingie. Leonard wonders if she is upset and Sheldon correctly guesses that she is.

The Monopolar Expedition 4

Up at the magnetic North Pole.

Sheldon gets his time in the Cheesecake Factory freezer. His crew must practice using tools in the extreme cold which Sheldon had to improvise. Leonard is using an old calculator. Raj paints sideburns and a Van Dyke beard on a six inch high action figure. Howard must operate using a vintage Operation game. None of the guys is accomplishing his task in the cold, when they realize that they could assemble the equipment in the warm cabin before taking it outside. This thought never occurred to Sheldon who remarks, "I guess we're done here."

While enjoying a hot chocolate with a stick of butter or a stick of "I Can't Believe It's Not Butter" for the lactose-intolerant Leonard, Raj is in an argument with his parents about going on the North Pole. Howard had convinced his mother to let him go so he puts them on the phone together. Then she cries, “Arctic? I thought you were going to Arkansas!” Penny asks to see Leonard who is happy to removed himself from the arguments. Penny then presents him with a blue blanket with sleeves, a Snuggie that she saw on an infomercial to keep him warm while he does his science stuff. Penny hugs him, which Leonard returns. Her hug lasts so long that he hugs her twice. She leaves and Leonard returns to apartment 4A looking confused. Meanwhile, Mrs. Wolowitz is exclaiming that she can't understand why there's not a single Outback Steakhouse in all of India. That night Leonard is wondering whether he should go because of Penny. Sheldon tests him that he shouldn't go which also turns into one of his classic pranks. Bazinga!

Early the next morning Leonard knocks on Penny's door holding his Snuggie. He asks about the “I’ll miss you,” and she replies that he'll be gone and she'll miss him. Then he asks about the blanket and Penny quips that wine, credit card and late-night TV is a bad combination. Finally he wonders about the long hug that lasted at least five Mississippi's. Penny tells him that it was just a hug and she wishes him a safe trip. She closes the door and leaning on it sighs to herself, “It means I wish you weren't going."

At the magnetic North Pole, as usual they are preparing Thai food, though reconstituted. The hut is set up with the same furniture arrangement as Apartment 4A. After considering that they are at the top of the world they decide on a movie marathon of Ice Station Zebra and John Carpenter's The Thing. Howard whispers to Raj to forget the crossbow, and find him an icicle.



  • "The Leonard and Penny relationship has been on the back burner all season and so this low key acknowledgment of her feelings felt appropriate. The show is probably going to be around for years to come so the producers are in no hurry to change the dynamics of the group yet...Instead of that scene we could have been exploring how Leonard and Penny feel about each other and why. Again there are so many simple things which the show could do to help build their relationship up as a more realistic entity...This episode sums up the whole of season two of the show. It’s too reliant on Sheldon, not focused on character development and too static for my tastes. On the flip side it is also funny, consistent and showcases a genuinely strong comic character." - The TV Critic's Review
  • IMDb user reviews


  • Title Reference: The title refers to the scientific expedition that the gang is taking to the North Pole.
  • Chuck Lorre's vanity card [1]
  • This episode was watched by 9.81 million people with a rating of 3.7 (adults 18–49).
  • Episode transcript [2]

Costume Notes[]


Green Lantern


De Oxy Ribo


Penrose triangles


Robot evolution

Sheldon wears a Green Lantern logo shirt, the De Oxy Ribo shirt from Thinker Collection, the Penrose Triangles shirt originally from Heavy Rotation, and his red Robot Evolution shirt.








Leonard wears his "Twisted" Rubik's cube shirt, his green recycle logo shirt, an unknown brown shirt with yellow fish, his purple "Wisdom" shirt, by Ames Brothers, featuring an owl, and the adrenaline molecule shirt.

Set/Props Notes[]

New on the set:

In Sheldon's bedroom: 2 comics in the bins, 4 books on the shelves, and 1 text on the nightstand:

The Monopolar Expedition 22 - Batman 23

Action #851


Kirby Omnibus 1


Kirby Omnibus 2

Batman Annual #23
September 1999
Action Comics #851
August 2007
Jack Kirby Omnibus 1
Starring Green Arrow
Jack Kirby Omnibus 2
The Super Powers

Kirby Omnibus 3


Kirby Omnibus 4

Statistical Physics

Statistical Physics

Jack Kirby Omnibus 3
Fourth World
Jack Kirby Omnibus 4
Fourth World
Statistical Physics
Reprint of the John Wiley & Sons, New York, 1966 edition.

At the Cheesecake Factory


Legolas figurine

In the hallway

The Monopolar Expedition 5


Leonard's snuggie


  • First season finale in which main characters (minus Penny) go on a trip.
  • Sheldon is upset at knowing that something important is on the horizon, but having no clue as to what it might be; comparing himself to a Heisenberg particle. German physicist Werner Heisenberg found that just the act of observing a particle can have an effect on the behavior of that particle. To know how fast something is going, you have to measure it, and measuring it impacts it's speed. So you can know WHERE something is, OR how fast it's going, but not both; not without impacting the thing. Or, in considering location and motion, the more you know about ONE element, the LESS you know about the other (i.e.: Heisenberg's Uncertainty Principle)
  • Sheldon tells Raj to paint and a Van Dyke beard on a six-inch figurine of Legolas. Sheldon incorrectly defines a Van Dyke beard as a goatee without a mustache, when in fact a Van Dyke is a goatee with a mustache.
  • When Sheldon says "logic dictates," he mimics Spock's words, memorably stated in Star Trek II: The Wrath of Khan and the Star Trek episode "The Savage Curtain". Similarly, in "The Bat Jar Conjecture" (S1E13), he purports, "No man should be forced to emblazon his chest with the Bengal tiger, when common sense dictates it should be an army ant."
  • Howard, annoyed with Sheldon, pretends to take an arrow from a quiver on his back, puts in an imaginary crossbow and fires at Sheldon's back, but he does a shotgun sound with his mouth.
  • Penny again can't tell Leonard how she feels about him and it is the first time she even mentions her feeling for him.
  • First time Sheldon uses his catchphrase "Bazinga".
  • In "The Bad Fish Paradigm" (S2E1), several ways are stated regarding how to annoy Sheldon. One of them was "Talk to him through the bathroom door"; however, in this episode it is shown that Sheldon talks to Leonard while he (Leonard) was in the bathroom. It may mean that Sheldon doesn't mind talking through the bathroom door as long as he is outside the bathroom.
  • In the final scene in the Arctic hut, Leonard remarks that "This is literally the top of the world". This is an error by the scriptwriters, in that the Earth's axis is not vertical and so the North Pole is not "literally the top of the world". There have actually been scenes when the nerds have themselves made an issue of such misuse of the word 'literally'. Also, the guys were at the magnetic North Pole which not at latitude 90 degrees. Magnetic north changes from year to year. Still they are further North than 99.9999% of the people on Earth.
  • They refer to the magnetic North Pole as the North Pole, but the North Pole is actually the magnetic South Pole, for opposite charges attract, and a compass's north point points to the North Pole, indicating that it is really pointing at the magnetic South Pole.


Penny: Sheldon says you’re going to the North Pole.
Leonard: Yeah. Pretty cool, huh?
Penny: Yeah. I’m just a little surprised you didn't tell me.
Leonard: Oh, well, it all happened kind of fast, and we had to get physicals and buy thermal underwear and study up on, you know, snow and stuff. Sorry, I was gonna tell you.
Penny: Oh, hey, no, you don’t have to apologize. There’s no reason you have to tell me. I was just, you know, surprised.

Penny: Well, I got you a little going away present.
Leonard: Oh, a blanket.
Penny: Oh, no, no, no, not just a blanket. See, it has sleeves. Yeah! So, you can, you know, be all snoodled up while you do your science stuff.
Leonard: Oh, wow, cool.
Penny: Oh, I’m gonna miss you. (She hugs him for a long time) See you later.

Penny: Oh, Leonard, what time is it?
Leonard: Its 7 a.m. I’m sorry it’s early, but we’re leaving soon, and I needed to talk to you.
Penny: Okay.
Leonard: What did you mean when you said you’re going to miss me?
Penny: Um, I don’t know. You’ll be gone and I’ll notice.
Leonard: (indicating the blanket) Okay, well, um, what about this? What does this mean?
Penny: Wine, credit card and late night television are a bad combination.
Leonard: All right, fine. What about that really long hug? What did that mean?
Penny: That wasn't a long hug.
Leonard: It was at least five Mississippi’s. A standard hug is two Mississippi’s tops.
Penny: Leonard, I don’t know what to tell you. It was just a hug.
Leonard: Glad we cleared that up.
Penny: Yeah.
Leonard: I guess I’ll see you.
Penny: Okay, have a safe trip.
Leonard: Thank you. Bye.
Penny: Okay, bye. (Penny closes door. To herself) It means I wish you weren’t going.

Mrs. Koothrappali: Why won't you believe me?
Mrs. Wolowitz: 'Cause it doesn't make sense to me! How can it be that in the whole country of India, there is not even one Outback Steakhouse?