Sir Ernest Rutherford, President of the Royal Academy, and recipient
of the Nobel Prize in Physics, related the following story:

Some time ago I received a call from a colleague. He was about to
give a student a zero for his answer to a physics question, while the
student claimed a perfect score. The instructor and the student agreed
to an impartial arbiter, and I was selected. I read the examination
question: "Show how it is possible to determine the height of a tall
building with the aid of a barometer." The student had answered: "Take
the barometer to the top of the building, attach a long rope to it,
lower it to the street, and then bring it up, measuring the length of
the rope. The length of the rope is the height of the building." The
student really had a strong case for full credit since he had really
answered the question completely and correctly! On the other hand, if
full credit were given, it could well contribute to a high grade in his
physics course and certify competence in physics, but the answer did not
confirm this. I suggested that the student have another try.

I gave the student six minutes to answer the question with the
warning that the answer should show some knowledge of physics. At the
end of five minutes, he hadn't written anything. I asked if he wished to
give up, but he said he had many answers to this problem; he was just
thinking of the best one. I excused myself for interrupting him and
asked him to please go on. In the next minute, he dashed off his answer,
which read: "Take the barometer to the top of the building and lean
over the edge of the roof. Drop the barometer, timing its fall with a
stopwatch. Then, using the formula x=0.5*a*t^2, calculate the height of
the building."

At this point, I asked my colleague if he would give up. He
conceded, and gave the student almost full credit. While leaving my
colleague's office, I recalled that the student had said that he had
other answers to the problem, so I asked him what they were. Well, "said
the student, "there are many ways of getting the height of a tall
building with the aid of a barometer. For example, you could take the
barometer out on a sunny day and measure the height of the barometer,
the length of its shadow, and the length of the shadow of the building,
and by the use of simple proportion, determine the height of the
building.""Fine," I said, "and others?"

"Yes," said the student, "there is a very basic measurement
method you will like. In this method, you take the barometer and begin
to walk up the stairs. As you climb the stairs, you mark off the length
of the barometer along the wall. You then count the number of marks, and
this will give you the height of the building in barometer units. A
very direct method." "Of course. If you want a more sophisticated
method, you can tie the barometer to the end of a string, swing it as a
pendulum, and determine the value of g [gravity] at the street level and
at the top of the building. From the difference between the two values
of g, the height of the building, in principle, can be calculated. On
this same tack, you could take the barometer to the top of the building,
attach a long rope to it, lower it to just above the street, and then
swing it as a pendulum. You could then calculate the height of the
building by the period of the precession". "Finally," he concluded,
"there are many other ways of solving the problem. Probably the best,"
he said, "is to take the barometer to the basement and knock on the
superintendent's door. When the superintendent answers, you speak to him
as follows: 'Mr. Superintendent, here is a fine barometer. If you will
tell me the height of the building, I will give you this barometer."

At this point, I asked the student if he really did not know the
conventional answer to this question. He admitted that he did, but said
that he was fed up with high school and college instructors trying to
teach him how to think.

The name of the student was Niels Bohr." (1885-1962) Danish
Physicist; Nobel Prize 1922; best known for proposing the first 'model'
of the atom with protons & neutrons, and various energy states of
the surrounding electrons - the familiar icon of the small nucleus
circled by three elliptical orbits ... but more significantly, an
innovator in Quantum Theory.

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