The Man Who Tried To Kill Doppler
The News would hardly be exciting without scandal, intrigue, adversaries, and conspiracy theories, right?
The year is 1845, a time where the physical sciences were being aggressively investigated by experimentation and in particular - physics. Competition for recognition was at an all time high. Many theories were proposed and many theories were shot down. A frenzy of papers were published by notable scientists and quacks vying for prestige.
While you know the story of Christian Doppler, see "The Use of Doppler Ultrasound in Cardiovascular Disease", you probably did not know about his arch-nemesis, Buys Ballot.
Doppler had just released a paper entitled "On the Coloured Light of Double Stars and Some Other Heavenly Bodies" where he postulated that the light coming from stars had a peculiar shift in the light spectrum that depended on the relative motion of the observer with the source of the light. He explained that the colors of the star shifted relative to the motion of the earth. The blue stars were moving towards the earth while red stars were moving away.
Doppler, at the time, never applied that theory to sound waves. But, another scientist did.
Buys Ballot, a Dutch scientist and Doppler's rival, attempted to kill Doppler's idea that objects moving towards the observer displayed an increase in frequency and objects moving away from the observer displayed a decrease in frequency.
It would be Buys Ballot that provided us with the famous example of a moving train.
Buys, in an attempt to disprove Doppler's description, created the classic experiment. He arranged to have a train he borrowed from the Dutch government to carry a trumpeter on to play a specific note. The many observers he coaxed into remaining at the station where two other trumpeters played the very same note, waited to see the Doppler Effect fail.
What actually happened was the pitch of the note increased as the train moved towards the observers and as it sped away, the note decreased in pitch.
Buys Ballot, much to his chagrin, actually proved the Doppler Effect worked. In addition, he showed that the property acted not only on light but on sound.
The Doppler Effect is applied to astronomy, acoustics, meteorology, radar, sonar, satellite communications, developmental biology, and medicine, however, our use of the Doppler Effect in determining blood flow velocity is not dependent on the frequency shift (Doppler shift) but on the phase shift. The phase shift is determined by the amount of time it takes for the signal to return. Calculating the phase shift determines the velocity and direction of blood flow in the cardiovascular system.
The Familiar Doppler Equation used in ultrasound
Buys Ballot was not without his own contributions to science. He is well known in the area of meteorology and was the first chairman of the International Meteorological Organization.
Buys Ballot's law states that if an observer, located in the northern hemisphere, stands with his back to the wind, the pressure is higher on the right than on the left. It occurs in the opposite way in the southern hemisphere.
This model of atmospheric properties illustrates the pressure gradients we see in today's weather mapping and the coming of clear skies or stormy weather. These are the "high" and "low" pressure systems reported to us every day.
While Buys Ballot did not "kill off" Doppler's principle, both men laid the ground work for many of the technologies we use today.
Richard Keith H. Duncan
Kisslo, Joseph A., David Adams, and Robert N. Belkin. Doppler Color Flow Imaging. New York: Churchill Livingstone, 1988. Print.
"C. H. D. Buys Ballot." Wikipedia. Wikimedia Foundation, n.d. Web. 24 May 2016.
"Buys Ballot's Law." Wikipedia. Wikimedia Foundation, n.d. Web. 24 May 2016. <https://en.wikipedia.org/wiki/Buys_Ballot's_law>.
"Christian Doppler." Wikipedia. Wikimedia Foundation, n.d. Web. 24 May 2016. <https://en.wikipedia.org/wiki/Christian_Doppler>.
Images: Wikipedia CC