Wednesday, May 26, 2010

Most Elegant Experiment of All Time

The Doppler Effect—Waves emitted by a source moving from the right to the left. The frequency is higher on the left (ahead of the source) than on the right.

Here is a web-sensation "scientific experiment" (you saw it on Yahoo).
--But I know an experiment that "trumps" it big-time!

First, this experiment from Jeanne Marie Laskas, advice columnist at Reader’s Digest -presumably done in her own kitchen at home:

"Does the toast really always fall buttered-side down?

Scientists in the Ask Laskas Kitchen conducted a study for which they first toasted an entire loaf of bread, one slice at a time. They buttered each slice, and dropped it from a variety of heights ranging from tabletop to ceiling. Among their findings: A dropped piece of toast never lands on its edge; stomping your foot and yelling "Darn!" does not change a thing. . ."
Ask Laskas link here

The Most Elegant Experiment of All Time

Here however, history provides us with what has often been called “the most elegant experiment of all time,” performed by Christian Johann Doppler (1803-1853), an Austrian experimental physicist and mathematician, living in Prague at the time. His experiment "trumps" the Laskas experiment in every way possible.

1845: An early English steam locomotive hauling a tender and three carriages adapted from horse-drawn coaches. (Photo: Lambert/Getty Images)

"Doppler reasoned that if a source of sound is moving toward a listener, the waves in front of the source are compressed, thus creating a higher frequency. On the other hand, the waves behind the moving source are stretched out, resulting in a lower frequency.
“After developing a mathematical formula to predict this effect, Doppler presented his findings in 1842.

"Three years later, he and Dutch meteorologist Christopher Heinrich Buys-Ballot (1817-1890), a professor in Utrecht, conducted a highly unusual experiment to demonstrate the theory, near the Dutch town of Maarson, along the Rhine Railroad.

"There is a minority version of the story, that Buys-Ballot was one of Doppler’s critics, and performed this experiment hoping to disprove Doppler's theory, but ended up verifying it instead.

“Buys-Ballot arranged for a band of trumpet players to perform on an open railroad flatcar, playing a calibrated note on a steam locomotive on the Utrecht-Amsterdam line, while riding past a platform on which a group of musicians with perfect pitch. . . sat listening."

"The listeners stood on the platform and wrote down what note they heard as the train approached and then receded. What the listeners wrote down was consistently first slightly higher and then slightly lower than what the moving musicians actually played.

"Sources vary as to whether the musicians were playing in the key of E flat, A, or A sharp! Perhaps all of them, at different times?

“The experiment went on for two days, the flatcar passing by again and again, while the horns blasted and the musicians on the platform recorded their observations.

“Doppler repeated the experiment with a second group of stationary trumpet players on the station platform to provide a reference. They and the moving musicians played the same note as the train passed. Listeners could clearly hear that the notes sounded different. The moving and stationary notes seemed to interfere, setting up a pulsing beat.”

Trumpet in F by John August Köhler, London, ca. 1838 
Utley Virtual Gallery website link

“Though Doppler and Buys-Ballot must have seemed like crazy men to those who were not involved in the experiment, the result—as interpreted from the musicians' written impressions of the pitches they heard—confirmed Doppler's theory."

“At the time when Doppler announced his findings, there was no easy means to test them. The fastest form of transport which carried a horn was the horse-drawn mail coach. This only moved at about ten miles an hour – too slow for the Doppler Effect to be noticeable. It was only in 1845, when a scientist took a trumpet aboard a train locomotive, that the effect was first demonstrated.”

"Doppler chose sound waves as a more convenient means of confirmation, since it was by then feasible to make a train travel the 70 kilometer per hour [another source says 60] needed for the experiment. Yet the first experiment, in 1845, failed. The train did not manage to travel at a constant speed, and the hired trumpet players (one group on the train and three groups along the tracks) were not disciplined enough to play the right tones at the right moments.”

"Doppler never enjoyed the fame he sought. He died at the age of 50 in 1853, just as the scientific community was beginning to accept, and see the value of, his discovery.”

A direct-quote collation of these sources, that is, a free-editing and interweaving of direct quotes from these five sources:

Science of Everyday Things:
Kendall Haven
Estafanous, Barash & Reves
David Darling
Lofgren & Wilk

No comments: