Sommerfeld (1868-1954), trolley cars were cooled in summer by two
small fans set into their ceilings. When the trolley was in motion, air
flowing over its top would spin the fans, pulling warm air out of the cars.
One student noticed that although the motion of any given fan was fairly
random---fans could turn either clockwise or counterclockwise---the
two fans in a single car nearly always rotated in opposite directions.
Why was this? Finally he brought the problem to Sommerfeld.
"That is easy to explain," said Sommerfeld. "Air hits the fan at
the front of the car first, giving it a random motion in one direction.
But once the trolley begins to move, a vortex created by the first fan
travels down the top of the car and sets the second fan moving in
precisely the same direction."
"But, Professor Sommerfeld," the student protested, "what hap-
pens is in fact the opposite! The two fans nearly always rotate in
"Ahhhh!" said Sommerfeld. "But of course that is even easier to
Wolfgang Pauli (1900-1958), the father of the Pauli Exclusion
Principle for electrons, had very exclusive views about who should
and should not be accounted a physicist. Young prodigies were the
target of his special scorn. "So young, and yet---" he said of one,
"---already he has done so little."
This put Pauli's students in an unenviable position. When asked
to write a recommendation, Pauli would instead make a list of all the
student's faults. There was one student so brilliant, however, that
even Pauli could write nothing less than a glowing recommendation,
to wit, "I have nothing against this man."
"One word characterizes the most strenuous of the efforts for the
advancement of science that I have made perseveringly during
fifty-five years; that word is failure."
"I have long discovered that geologists never read each other's works,
and that the only object in writing a book is a proof of earnestness."