Leonard: So you just shut the door in his face? I got to start writing this stuff down.

Leonard: Penny, as a scientist, my job is to figure out why things happen. But I don't think I'll ever understand how someone like me could get to be with someone like you. You know maybe I don't need to understand it, I just need to be grateful. I love you, Penny.

Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis?
Sheldon: Screwed?
Leonard: There you go.

Leonard: My point is, while you're spending all this time on your own, building computers or practicing your cello, what you're really doing is becoming interesting. When people finally do notice you, they're gonna find someone a lot cooler than they thought. And for those of you that were popular in high school, it's over, sorry. Thank you. Congratulations.

Sheldon: They're very different. Physics answers the question: what is the nature of the universe? Geology answers the question: you know, what'd I just trip over?

Raj: Are you saying that you don't believe two people fall in love?
Ruchi: Of course they do. It's just that what people call "love" is actually a series of biochemical reactions in the brain that fade over time.
Raj: Yes. Like the old song, "When a man has a biochemical reaction for a woman."

Sheldon: I've been modeling different types of dark matter and the traces they would leave on the zircon inside your meteorite.
Bert: What's this one here?
Sheldon: That's actually a dark matter model of my own creation. I call it the Cooper Boson.
Bert: Cool. I got to name a rock once. I named it Moderately Sedimented Shale. Guess I kind of pooped the bed on that one.