A joke along these lines has the math professor claiming that the proof of some statement is trivial. They pause for a moment, think, then leave the classroom. Half an hour later, they come back and say, “Yes, it was trivial.”
I heard about a professor (I think physics) who was always telling his students that various propositions were “simple”, despite the fact that the students always struggled to show them. Eventually, the students went to the TA (the one I heard the story from), who told the professor.
So, the next class the professor said, “I have heard that the students do not want me to say ‘simple’. I will no longer do so. Now, this proposition is straightforward...”
At the Princeton graduate school, the physics department and the math department shared a common lounge, and every day at four o’clock we would have tea. It was a way of relaxing in the afternoon, in addition to imitating an English college. People would sit around playing Go, or discussing theorems. In those days topology was the big thing.
I still remember a guy sitting on the couch, thinking very hard, and another guy standing in front of him, saying, “And therefore such-and-such is true.”
“Why is that?” the guy on the couch asks.
“It’s trivial! It’s trivial!” the standing guy says, and he rapidly reels off a series of logical steps: “First you assume thus-and-so, then we have Kerchoff’s this-and-that; then there’s Waffenstoffer’s Theorem, and we substitute this and construct that. Now you put the vector which goes around here and then thus-and-so...” The guy on the couch is struggling to understand all this stuff, which goes on at high speed for about fifteen minutes!
Finally the standing guy comes out the other end, and the guy on the couch says, “Yeah, yeah. It’s trivial.”
We physicists were laughing, trying to figure them out. We decided that “trivial” means “proved.” So we joked with the mathematicians: “We have a new theorem—that mathematicians can prove only trivial theorems, because every theorem that’s proved is trivial.”
The mathematicians didn’t like that theorem, and I teased them about it. I said there are never any surprises -- that the mathematicians only prove things that are obvious.
A joke along these lines has the math professor claiming that the proof of some statement is trivial. They pause for a moment, think, then leave the classroom. Half an hour later, they come back and say, “Yes, it was trivial.”
I heard about a professor (I think physics) who was always telling his students that various propositions were “simple”, despite the fact that the students always struggled to show them. Eventually, the students went to the TA (the one I heard the story from), who told the professor.
So, the next class the professor said, “I have heard that the students do not want me to say ‘simple’. I will no longer do so. Now, this proposition is straightforward...”
-- Surely you’re joking, Mr. Feynman!