While lecturing on ideal gases one day, Ludwig Boltzmann casually mentioned a number of complex calculations, with which he apparently assumed his students were equally familiar. Near the end of the class, the students, utterly unable to follow his progress, asked Boltzmann to do his calculations on the blackboard. The professor apologized and promised to do better next time...
Soon enough, the next lesson arrived. "Gentlemen," Boltzmann began, "if we combine Boyle's Law with Charles' Law we get the equation pv = psub 0 vsub 0 (1 + a t)... Now it is clear that sub a S sup b = f(x) dx x (a), so pv = RT and sub V S f(x,y,z) dV = 0... It is as simple," he declared, "as one and one equals two."
Then, suddenly recalling his promise from the previous class, he dutifully wrote "1 + 1 = 2" on the blackboard before continuing with the lecture.
[Boltzmann's famous equation S = K log W (where S = entropy, K = Boltzmann's constant, and W = probability of a particular state) was inscribed as an epitaph on Boltzmann's tombstone.]
