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Editorial: Creativity and the scientific method

by Geoff Hart

Previously published as: Hart, G.J. 2003. Editorial: Creativity and the scientific method. the Exchange 10(3):2, 4.

There's an old joke that refers to a possibly apocryphal physics exam. In this particular exam, one question asked students to describe how they would determine the height of a tall building using only a barometer. Since barometers are designed to measure air pressure, and since air pressure decreases in a mostly predictable fashion with increasing height above ground, the teacher was presumably seeking a simple answer based on this physical principle.

Students of science, being notoriously recalcitrant, have come up with a variety of creative alternatives that avoid complying with the professor's desire without actually getting into a fight over it. These include a variety of amusing, though practical alternatives:

Tie the barometer to a long rope, then lower it from the roof until it touches the ground. The sum of the length of rope and the barometer's length add up to the height of the building. (Unfortunately, this solution violates the letter of the question, if not its spirit, because you would need additional equipment—a ruler of some sort, say—to measure the two lengths.)
A corollary to the first option: If you can walk up the stairs from ground level to the roof, you can use the barometer as a ruler and determine how many barometers high the building is. (Same objection, of course.)
Use some applied geometry. If the sun is up, place the barometer beside the building and measure the lengths of their respective shadows. The ratio of one shadow to the other is the same as the ratio of their respective heights, so figuring out the building's height is a simple matter of proportion. (Same problem as the first two solutions.)
Drop the barometer off of the roof and measure the time required for it to reach the ground. The building's height can then be calculated using Newton's formula for the distance traveled during acceleration. (This is also cheating, since you'd need a timepiece to measure the duration of the barometer's last few moments as a functioning instrument).
Use the physics of pendulums to estimate the distance. The simpler method is to tie the barometer to a rope long enough for the barometer to just miss brushing the ground, then measure the duration of its swing. Alternatively, use a shorter length of rope to measure the pendulum's period at ground level and on top of the building; the difference between the two depends on differences in the strength of the gravitational field experienced by the pendulum. Knowing the gravitational constant and Earth's diameter, you can calculate the height difference between ground and roof based on the difference in the gravitational field. (You still need to cheat by using a timepiece.)
My favorite solution involves offering the barometer as a bribe to the building's architect (or a clerk at the land registry) if they'll tell you the building's height. That requires no additional instrumentation, and thus meets the letter of the rules, if not their spirit (i.e., to apply the scientific method to solving the problem).

At first glance, it seems like none of the solutions honor both the letter and the spirit of the original problem. But it's worth noting that the most interesting and important studies in the history of science have come from thinking outside the box and trying something other than the expected approach. That's something we scientific communicators should bear in mind in responding to our own daily tests.

(Historical footnote: The original student claimed to be responsible for all of these solutions was Niels Bohr, Danish Nobel laureate in Physics. If true, the story illustrates nicely how his creativity in a simple test was only one early symptom of future greatness.)

My essays on scientific communication have now been collected in the following book:

Hart, G. 2011. Exchanges: 10 years of essays on scientific communication. Diaskeuasis Publishing, Pointe-Claire, Que. Printed version, 242 p.; eBook in PDF format, 327 p.