At 13:45 in this interview from 2003, Sergey Brin and Larry Page try to explain idempotence to Terry Gross (NPR's Fresh Air host):
http://www.npr.org/2003/10/14/167643282/google-founders-larr...
(It does not go very well.)
Edit: I can't find a transcript, so I just transcribed that portion of the interview myself, starting at 13:45:
TG: Now I'll tell you, in preparing for this, I decided, let me Google Google, so I typed in "Google" into the Google search, and I came up with a lot of Google things in the regular search, but in the "Are you feeling lucky?" search, I got nothing.
LP: Well you just got Google itself.
TG: Yeah, I just got Google itself. Oh, I see, Google was giving me itself.
LP: Yeah.
TG: Oh.
LP: In computer science, we call that recursion. [laugh].
TG: Oh, you even have a name for it. [laugh]. I didn't quite get that. I kept thinking it was just repeating itself. I didn't realize it was giving me itself. [laugh].
LP: [laugh]
TG: And what's the name for it?
LP: Uh, recursion. It's... kind of... Sergey is giving me a dirty look.
TG: Why?
LP: It's a loose definition. [laugh]
TG: Lighten up Sergey. [laugh]
LP: It's a loose interpretation of... [laugh]... recursion.
TG: Sergey, what's the more literal interpretation?
SB: The technical term is you got itself back.
TG: Right?
SB: There's not really much beyond that. [laugh]
TG: Okay.
SB: Idempotence. How about that.
TG: Say it again.
SB: Idempotence.
TG: What is it?
SB: That's when you uh... [laugh]... Maybe I should stop while I'm ahead...
TG: ...You're just making this up, aren't you...
SB: ...Before I dig a deeper hole. Idempotence is when you do something and you get the original thing back.
TG: Oh, so that's a real word?
LP: It's a mathematical term.
SB: Yeah, yeah, but it's also just as loose an interpretation as Larry's was of recursion.
http://www.npr.org/2003/10/14/167643282/google-founders-larr...
(It does not go very well.)
Edit: I can't find a transcript, so I just transcribed that portion of the interview myself, starting at 13:45:
TG: Now I'll tell you, in preparing for this, I decided, let me Google Google, so I typed in "Google" into the Google search, and I came up with a lot of Google things in the regular search, but in the "Are you feeling lucky?" search, I got nothing.
LP: Well you just got Google itself.
TG: Yeah, I just got Google itself. Oh, I see, Google was giving me itself.
LP: Yeah.
TG: Oh.
LP: In computer science, we call that recursion. [laugh].
TG: Oh, you even have a name for it. [laugh]. I didn't quite get that. I kept thinking it was just repeating itself. I didn't realize it was giving me itself. [laugh].
LP: [laugh]
TG: And what's the name for it?
LP: Uh, recursion. It's... kind of... Sergey is giving me a dirty look.
TG: Why?
LP: It's a loose definition. [laugh]
TG: Lighten up Sergey. [laugh]
LP: It's a loose interpretation of... [laugh]... recursion.
TG: Sergey, what's the more literal interpretation?
SB: The technical term is you got itself back.
TG: Right?
SB: There's not really much beyond that. [laugh]
TG: Okay.
SB: Idempotence. How about that.
TG: Say it again.
SB: Idempotence.
TG: What is it?
SB: That's when you uh... [laugh]... Maybe I should stop while I'm ahead...
TG: ...You're just making this up, aren't you...
SB: ...Before I dig a deeper hole. Idempotence is when you do something and you get the original thing back.
TG: Oh, so that's a real word?
LP: It's a mathematical term.
SB: Yeah, yeah, but it's also just as loose an interpretation as Larry's was of recursion.