The Slashdot discussion on “the most beautiful physics experiment” makes for some fun reading. My personal vote goes for Eddington’s validation of relativity, which another Slashdotter mentioned, but this passage in the ensuing discussion was just wonderful.
Ok, so this is probably apocryphal, but I was sent this a while ago:
A question in a physics degree examination at the University of Copenhagen ran thus:
“Describe how to determine the height of a skyscraper with a barometer.”
One student replied: “You tie a long piece of string to the neck of the barometer, then lower the barometer from the roof of the skyscraper to the ground. The length of the string plus the length of the barometer will equal the height of the building.”
This highly original answer so incensed the examiner that the student was failed immediately. He appealed on the grounds that his answer was indisputably correct, and the university appointed an independent arbiter to decide the case. The arbiter judged that the answer was indeed correct, but did not display any noticeable knowledge of physics. To resolve the problem it was decided to call the student in and allow him six minutes in which to provide a verbal answer which showed at least a minimal familiarity with the basic principles of physics. For five minutes the student sat in silence, forehead creased in thought. The arbiter reminded him that time was running out, to which the student replied that he had several extremely relevant answers, but couldn’t make up his mind which to use. On being advised to hurry up the student replied as follows:
“Firstly, you could take the barometer up to the roof of the skyscraper, drop it over the edge, and measure the time it takes to reach the ground. The height of the building can then be worked out from the formula H = 0.5g x t squared. But bad luck on the barometer.
“Or if the sun is shining you could measure the height of the barometer, then set it on end and measure the length of its shadow. Then you measure the length of the skyscraper’s shadow, and thereafter it is a simple matter of proportional arithmetic to work out the height of the skyscraper.
“But if you wanted to be highly scientific about it, you could tie a short piece of string to the barometer and swing it like a pendulum, first at ground level and then on the roof of the skyscraper. The height is worked out by the difference in the gravitational restoring force T = 2 pi sqrroot (l / g).
“Or if the skyscraper has an outside emergency staircase, it would be easier to walk up it and mark off the height of the skyscraper in barometer lengths, then add them up.
“If you merely wanted to be boring and orthodox about it, of course, you could use the barometer to measure the air pressure on the roof of the skyscraper and on the ground, and convert the difference in millibars into feet to give the height of the building.
But since we are constantly being exhorted to exercise independence of mind and apply scientific methods, undoubtedly the best way would be to knock on the janitor’s door and say to him ‘If you would like a nice new barometer, I will give you this one if you tell me the height of this skyscraper’.”
The student was Niels Bohr.
A great example of how there are always different ways of looking at a problem, from one of the greatest scientists ever (allegedly)
There’s another apocryphal story that was kicking around during my physics undergrad days about a grad student’s Ph. D. oral exam. The anxious grad student was only asked one question: “Why is the sky blue?”
“Er, light waves are scattered by the Earth’s atmosphere”
“Could you explain that part a little bit more?
“Well, shorter wavelength light, such as blue, is more often absorbed by air particles and scattered”
“Could you explain that part a little bit more?
And so on through Rayleigh scattering down into the nuts and bolts of atomic/quantum theory. Finally after a couple hours of “could you explain that part a little bit more?” the examiners were satisfied and the grad student passed. Like I said, it’s proabably an academic legend (as opposed to an urban legend?) to scare the hell out of the undergrads, but it’s a good one.