Permanent Head Damage－－zz from http://math.ucr.edu/home/baez/gr/oz2.html

"This was once a student of mine, like you, eager to learn general relativity. He was an excellent student, much better than SOME, and he had progressed to the point where he was writing code to do numerical simulations of Einstein's equation. He was trying to figure out what happened when two black holes collide - a problem, by the way, that is still not fully understood."

"Anyway, he noticed a lot of problems. When he reduced the mesh size - never mind, this is just some jargon - sometimes his answers seemed to converge, other times not. He asked me about it so I suggested that he read a bit on numerical analysis. Oh, had I only known!" The wizard pauses sadly a moment.

"To understand the numerical analysis he realized he needed to learn a bit of analysis. After all, how could you compute the answer to something if you weren't sure the solution existed in the first place?? Pretty soon he was quite an expert on existence and uniqueness for nonlinear hyperbolic PDE. He studied Sobolev spaces, and energy bounds, and the work of Choquet-Bruhat...."

"But as he did he noticed something funny happening. Occaisionally he would feel a slight chill. He disregarded it and kept on working, delving ever more deep into nonlinear analysis. He lost interest in his original goal of simulating black hole collisions. Proving existence of solutions to equations seemed much more interesting than actually solving them. After a while he noticed frost forming on his glasses. He just wiped it off and kept on proving theorems. Unfortunately he failed to notice the icicles growing on his desk.... By the time we found him, it was too late. He was frozen solid, but still thinking about existence and uniqueness of solutions of nonlinear PDE...."

向耐心看完的同学表示orz