"if the mass is on an unstable point, then it rolls down and you cannot find it. forever."
like watching my phys professor, a well-known cosmologist in our phys department, fling a foot-long spring into the air with two heavy balls it, realize that it's going to crash onto of him, and duck to take cover.
or seeing him trying to demonstrate unstable eq. points on a potential function with a ball, realize the ball's going too fast for him to catch, and curse, waking all of us up since he's the most mild-mannered professor i've had :P
or my diffy Q's professor.. oh dear.
(all in an odd, french/russian accent?)
"here is a spring.. and this is a thing called a dash-board? dashboart? i have never heard of this before... to my understanding, it is a thin wire rod... but i may be mistaken... dashboard... hmm.."
"how did you come up with that equation?"
"um...mum mum mum.. you just have to see it. you know, spend a couple of afternoons thinking about it, and if you cannot get it, look in the book."
"... but slope fields are a little... how do you say it, slopy."
"this is who is not linear but it still smells like linear..."
"If h is greater than 4, you still have a chance for good things to happen..."
"do we have to know partial fractions for the prelim?"
"partial fractions? is that like.. adding fractions?"
"people are dying with constant speed."
"birth in equals birth out!"
".. and then you know, alligators will take over the world..."
"Doomsay... What is this? I never heard of it, is that the opposite of extinction?"
"it's Doomsday, professor."
"...ah, doomsday!.. really?"
and my all time favorite, while talking about population models --
"Every guy can be friends with every girl, then the birth rate is p squared, but they are probably not human...."
oh, i love the math and physics department at cornell =]