Monday, November 29, 2010

Christian Andreas Doppler

Christian Andreas Doppler was born on November, 29, 1803 in Salzburg, Austria. He was the son of a successful stonemason, but as he grew he was unable to work in his father's business due to his frailty and generally poor health. Doppler attended primary school in Salzburg and Secondary school in Linz. Unsure about the academic potential of their son, his parents consulted a mathematics professor who suggested that he study higher mathematics at the Vienna Polytechnic Institute. Doppler began his studies there in 1822. He excelled at mathematics and graduated in 1825. After graduation he returned to Salzburg, where he attended philosophy lectures at the Salzburg Lyceum and afterward studied higher mathematics, mechanics and astronomy at the University of Vienna.

At the end of his studies he was appointed assistant to mathematics professor A. Burg at Vienna University. He remained in this position for four years publishing papers on mathematics. At the age of 30 he began competing to find a permanent position. At that time open competitions were held to fill open professorships. Doppler competed for many positions and while he was waiting he supported himself by working as a bookkeeper for a cotton spinning factory. Despairing of not getting a position, Doppler sold his things in order to finance a trip to America, but before his final decision was made he was offered a position at the Technical Secondary School in Prague. Doppler was ambitious and wanted to do more than teach elementary mathematics. He applied to become a professor at the Polytechnic in Prague without success, until 1841 when he was appointed to the post.

Doppler's tenure at the Polytechnic was rocky and his students complained that his examinations were to difficult. He was reprimanded and forced to reexamine his students. In 1844 he was forced to give up teaching due to his poor health. He returned in 1846. Leaving his troubles in Prague behind he took a position as professor of mathematics, physics and mechanics at the Academy of Forests and Mines in Banska Stiavnica. As a result of the stormy revolutionary year 1848 Doppler sought refuge and went to Vienna, where he was appointed as the first director of the Institute of Physics at Vienna University.

Not all of Doppler's contemporaries considered him a brilliant mathematician, but he had an original way of looking at things that not all appreciated. For years Doppler attempted to become a member of the Bohemian Society, and despite good recommendations it was not until 1843 that he was elected in. In 1842 he presented a paper on the color of binary stars and how it is affected by their motion, to or away from the observer. Although the color changes of binary stars are not great enough to be significant, light is a wave and if a star emitting light is traveling toward the observer it will shorten the wavelength of light it is emitting moving it toward the red end of the visual spectrum. If the star is moving away from the observer the wavelengths grow longer, shifting the wavelength to the blue/violet end of the visible spectrum. These effects are called red shift and blue shift. This effect is most easily demonstrated with sound waves. A siren approaching the observer has a higher pitch than it would have if it were stationary with respect to the observer. As the siren passes the observer the pitch drops lower than it would have if it were stationary with respect to the observer. In 1845 Doppler performed an experiment with trumpeters on a railway car playing a single sustained note. As the railway approached and passed musicians recorded what notes they heard, demonstrating that the horn's pitch lowered as they passed the observer. This effect is called the Doppler effect.

Doppler died on March 17, 1853 in Venice, then a part of the Austrian Empire.

O'Connor, JJ and Robertson, EF; "Christian Andreas Doppler"; MacTutor History of Mathematics Archive; University of St. Andrews

Maizlin, Z.V.; The Wonders of Radiology; Create Space; 2010

Christian Doppler Wikipedia Entry

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