Christian Doppler
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Johann Christian Andreas Doppler (November 29, 1803 – March 17, 1853) was an Austrian mathematician and physicist, most famous for the hypothesis of what is now known as the Doppler effect which is the apparent change in frequency and wavelength of a wave that is perceived by an observer moving relative to the source of the waves.
Life
Christian Doppler was born in Salzburg, Austria, as the son of a well-to-do stone-mason, Johann Evangialist Doppler and his wife, Therese. A baptismal certificate indicates that Doppler was christened "Christian Adreas." Doppler was not of strong constitution, and did not follow his father into the construction trades. Instead, he was allowed to follow an academic track. His father asked the advice of Simon Stampfer, a local educator, as too the boy's future. Stampfer recognized Doppler's potential and recommended that his father send him to Vienna.<<<Maulik, Dev. 1997. Doppler ultrasound in obstetrics & gynecology. New York: Springer. 2. ISBN 0387942408.>>> After completing high school he spent three years at the Polytechnic Institute in Vienna, and returned to Saltzburg, where he completed his studies while tutoring mathematics and physics. He returned to the Polytechnic Institute for four years, where he taught higher mathematics. It was during this period that he wrote his first papers in mathematics and electricity.
Unable to find a teaching position, he contemplated a move to the United States. But after making preparations for the trip, he unexpectedly secured a post in 1835 as professor of mathematics and accounting at the State Secondary School in Prague. In 1841, he was employed at the State Technical Academy as a mathematics professor. A year later, in 1842, he read his first work on the changes in frequency of waves through a medium measured by an observer moving with respect to the waves' source. This has come to be known as the Doppler effect. The paper, presented before the Royal Bohemian Society of Sciences on May 25, 1842, was entitled On the colored light of the double stars and certain other stars of the heavens.<<<Hennerici, M., and Stephen P. Meairs. 2001. Cerebrovascular ultrasound theory, practice, and future developments. Cambridge: Cambridge University Press. 88.>>> His work was an extension of that of Edmond Bradley, the eighteenth century astronomer who measured the speed of light by noting the abberation that affects the apparent positions of all stars due to the orbital motion of the earth. Bradley made his calculations assuming a particle theory of light. But Doppler applied similar reasoning to show that the frequency of light would change if the observer was not stationary relative to the light source.
In Doppler's own words, "...nothing seems to be more intelligible than that to an observer the path length and the interim durations between two consecutive breakings of a wave must become shorter if the observer is hurrying toward the oncoming wave, and longer if he is fleeing from it..." As the frequency is dependent on the number of beats per unit time, and in light is related to the color perceived, Doppler concluded that the red color of some stars demonstrates that the perceived wavelength is greater as a result of the star and the earth moving away from each other."<<<Schuster, Peter. 2005. Moving the stars Christian Doppler, his life, his works and principle, and the world after. Pöllauberg, Austria: Living Edition. 63.>>>
On the colored light of the binary refracted stars and other celestial bodies - Attempt of a more general theory including Bradley's theorem as an integral part. ) An English translation of his original 1842 work in German can be found in the book by Alec Eden together with the German version. Besides light, Doppler also mentioned sound in his 1842 work. In this work, Doppler tried to explain the color of binary stars. Alec Eden did not feel confident regarding Doppler's conclusions regarding the color of binary stars but he was confident of Doppler's conclusions regarding the Doppler effect of sound. The Doppler effect of sound was verified by John Scott Russell in 1848. In his time in Prague as professor he published more than 50 articles in mathematics, physics and astronomy. (Note: The Bradley in the title of Doppler's 1842 work is James Bradley of Britain.)
His research career in Prague was interrupted by the revolutionary incidents of March 1848, when he fled to Vienna. There he was appointed head of the Institute for Experimental Physics at the University of Vienna in 1850. During his presence at the University of Vienna, Doppler, along with Franz Unger, played an influential role in the development of young Gregor Mendel who later became the founding father of genetics. (Note: Gregor Mendel studied in the University of Vienna from 1851 to 1853. At that time, Doppler served as a professor there.)
He died from a pulmonary disease in Venice at age 49 on March 17, 1853. His tomb can be found just inside the entrance of the Venetian island cemetery of San Michele. (Note: In 1853, Venice was also ruled by the emperor of Austria. It was like Doppler just moved from one part of the Austrian empire to another part of the same empire. Now Venice is part of Italy and so Doppler's tomb ends up in Italy instead of in Austria.)
See also
ReferencesISBN links support NWE through referral fees
<<Need at least 3 reliable references here, properly formatted.>>
- Schuster, Peter. 2005. Moving the stars Christian Doppler, his life, his works and principle, and the world after. Pöllauberg, Austria: Living Edition.; Webpage of the author)
- Alec Eden, "The search for Christian Doppler," Springer-Verlag 1992. (An English translation of Doppler's 1842 work on the Doppler effect can be found in this book. In this book, Alec Eden also made a detailed study regarding the full name of Christian Doppler. He believed that his full name should be "Christian Andreas Doppler".)
External links
- Christian Doppler and his birthplace in Salzburg
- John J. O'Connor and Edmund F. Robertson. Christian Doppler at the MacTutor archive
- Born between Salzburg and Braunau am Inn
Credits
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