Gary: I believe we have to look to gravity and its magnitude...
Adult Sheldon: I was really doing my best to hold it together.
Gary: ...could be a repulsive force if you just add negative mass.
Adult Sheldon: I smiled and nodded like my meemaw's Houston Oilers bobblehead.
Gary: And I also discovered a way that we could predict the masses of all the known particles using the Egyptian pyramids.
Adult Sheldon: In physics, there's a phenomenon known as supercritical assembly. If you bring enough material together in one place...
Gary: The trick is numerology.
Adult Sheldon: ...in the right configuration, eventually, it will explode.
Gary: This is fun. Not a lot of people I can talk to scientist-to-scientist.
Sheldon: We're not talking scientist-to-scientist. You're not a scientist. You're just a rich man that no one will be honest to because everyone wants your money.
President Hagemeyer: Oh, don't listen to him. I mean, he's just a kid. Why don't you tell me a little more about your pyramid thingy? Huh?

Principal Petersen: Our next young speaker needs no introduction, but that didn't stop him from writing one and making me read it. [laughter] "Fun fact." [audience groans, murmurs] I hear you. "The word 'valedictorian' is from the Latin 'valedicere,' meaning 'to say farewell.' It is primarily used in the United States, Canada, the Philippines and Armenia." Maybe that fact's more fun in Armenia. Please welcome your valedictorian, Sheldon Cooper.
Mary: Yay, Shelly!
Sheldon: Hello. I'm not very comfortable speaking in front of crowds. But there's a technique to reduce stage fright by focusing on one person in the audience and delivering your speech just to them. That's what I'll be doing today. If it weren't for this person, I wouldn't be here right now. They've taught me a lot, and it's by their example that I found the courage to move forward into this new and exciting chapter of my life. Missy... ...this is for you. Change can be scary, but I know we're going to be fine... ...because like you said, "It's okay to be scared. We just have to do it anyway." So if any of my fellow graduates are nervous about the future, know that you're not alone. I suggest you all try to be as brave as my twin sister. That's my plan. Missy, I wish I could give you advice about middle school, but I was so smart, I skipped it. If you make it to high school, we'll talk. Thank you. [applause]

Mary: Sheldon, faith means believing in something you can't know for sure is real. And right now, I am struggling with that.
Sheldon: So you don't believe in God anymore?
Mary: That isn't something for you to worry about. I need to figure this out myself.
Sheldon: Can I help? Maybe I could provide a fresh perspective.
Mary: I don't think so, baby.
Sheldon: Did you know that if gravity were slightly more powerful, the universe would collapse into a ball?
Mary: I did not.
Sheldon: Also, if gravity were slightly less powerful, the universe would fly apart and there would be no stars or planets.
Mary: Where you going with this, Sheldon?
Sheldon: It's just that gravity is precisely as strong as it needs to be. And if the ratio of the electromagnetic force to the strong force wasn't one percent, life wouldn't exist. What are the odds that would happen all by itself?
Mary: Why are you trying to convince me to believe in God? You don't believe in God.
Sheldon: I don't, but the precision of the universe at least makes it logical to conclude there's a creator.
Mary: Baby, I appreciate what you're trying to do, but logic is here. And my problem is here.
Sheldon: Well, there are 5 billion people on this planet and you're the perfect mom for me. What are the odds of that?

Missy: What's it like to not believe in God?
Sheldon: It's great. Big fan.
Missy: Are you ever afraid you're wrong?
Sheldon: About religion? Never. About other things? Also never.

George Jr.: See? They ain't allowed to dance, either.
Missy: It's like I'm watching my life.
George Jr.: That's how I feel when I'm watching Top Gun.

George Sr.: Come on, Sheldon, think of it as a free dinner.
Sheldon: I'm a kid. All my dinners are free.

Dale: Now, what do you think young people talk about on their dates?
Meemaw: I don't know. But my knee's telling me it's gonna rain this weekend.