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Eur J Echocardiography (2005) 6, 7e10 HISTORICAL NOTE Christian Andreas Doppler e the man and his legacy I.M. Coman) Iliescu Institute of Cardiovascular Diseases, 258 Fundeni Way, sect. 2, 022328 Bucharest, Romania Received 17 March 2004; received in revised form 19 May 2004; accepted 2 June 2004 KEYWORDS C.A. Doppler; Doppler effect; Medical applications Abstract Aims Reminding the life and legacy of the Austrian scientist who discovered the famous ‘Doppler Effect’. Methods and results C.A. Doppler was born the 29th of November 1803 in Salzburg. After studies in Linz and Vienna, he graduated in mathematics, became assistant at the University and later worked as professor in Prague. Back to Vienna, he was appointed as professor at the Polytechnic School anddin 1850das first director of the new Institute of Physics. C.A. Doppler did publish on magnetism, electricity, optics and astronomy. He remains in the history of science mainly due to the discovery presented (May 25, 1842) at the Royal Bohemian Society of Science entitled ‘‘On the colored light of the double stars and certain other stars of the heavens’’; the paper described (applied to light) the shift of frequency which bears nowadays his name. The theory was later experimentally proven anddextended for any electromagnetic and acoustic wavesdgot miriads of applications in astronomy, physics, aviation, meteorology and health science. Satomura in Japan (1955) published it’s first ultrasound vascular applicationdwith successive achievements in the next decades. Conclusion Doppler ultrasonography became the main noninvasive instrument for functional assessment of heart and vessels. –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Introduction The Austrian scientist who developed the famous ‘Doppler Effect’ was recently celebrated, during the Euroecho 7 meeting in Barcelona. It was a reminder to the memory of a surprising physician who’s brightest idea linksd160 years after being ) Tel./fax: D40-21-240-2224. E-mail address: [email protected]. 1525-2167/$30 doi:10.1016/j.euje.2004.06.004 publisheddsuch different areas as astronomy, spectroscopy, meteorology and health science. Walking through old Salzburg, one can discover, not far from the river, in Makart Platz, a fine baroque building anddon its wallda short notice reminding the birth of Christian Andreas Doppler (Fig. 1). For most of the academic world, the man is known as a physicist; but you can equally find him on lists of mathematicians or astronomers too; ‘the confusion’ is a proof for the exceptional broad spectrum of application of his main discovery. 8 I.M. Coman Figure 1 His life Christian Andreas Doppler was born in Salzburg, Austria, the 29th of November 1803 (Fig. 2).1,2 His ancestors were stonemasons anddaccording to the tradition of those times, he had to take over the family’s business. It was just his poor health deciding the parents to accept another career. Doppler attended primary school in Salzburg and secondary school in Linz (Upper Austria). In 1822, advised by some of his teachers, he Figure 2 C. Doppler’s birthplace in Salzburg. C.A. Doppler. began to study mathematics at the new Vienna Polytechnic Institute, graduating in 1825. A short break (with philosophy lectures attended at the Salzburg Lyceum) was followed by 2 more years of higher mathematics, mechanics and astronomy at the University of Vienna. It was here that he was appointed assistant to Professor A. Burg in 1829 and that was the moment of his first original paper (‘A contribution to the theory of parallels’). Unfortunately, his assistantship in Vienna was only temporary and the worst time of his youth (with months of unemployment and work as bookkeeper at a cotton factory) followed. Emigration to America seemed the solution (and he even visited the American Consulate in Munich to make preliminary arrangements). The USA lost a future citizen just because he was finally accepted as professor at the Technical Secondary School in Prague and later (1837) at the Polytechnic School, of the same city. It is during this Vienna staying that Doppler married and his numerous family (including three sons and two daughters) will bedthrough yearsdthe final result. The stay of C. Doppler in Bohemia ended in 1848. With a short stop at the Academy of Mines and Forests in Banska Stiavnica, Doppler’s family rejoined Vienna, where he became professor at the Polytechnic School, in 1849. One year later, he was appointeddon 17th of January 1850das the first director of the new Institute of Physics in Viennadthe highest point of his administrative career. Unhappily, health problems followed shortly thereafter (lung diseasedprobably tuberculosis); he had to move to an area with better climate but, despite medical care, he died in Venice on March 17, 1853. C.A. Doppler e the man and his legacy 9 His work His legacy During his lifetime, the man was quite controversial: a personality praised by some, but detested by others; and even as a scientist, he had a difficult time until being finally accepted for his brilliant ideas. C.A. Doppler did publish on magnetism, electricity, optics and astronomical topics, but for sure, the discovery that allowed him to remain in the history of science was the one he presented on the 25th of May 1842 at the Royal Bohemian Society of Science. The paper was called: ‘‘Über das farbige Licht der Doppelsterne und einiger anderer Gestirne des Himmels’’ (‘‘On the colored light of the double stars and certain other stars of the heavens’’) and it described (applied to light) the shift of frequency which is nowadays known as ‘Doppler effect’.3 It was not a perfect demonstration and the chosen example was wrong (the effect is too small to be significant for the colours of the stars). In spite of this, as Bolzano wrote ‘‘one can see the germ of some important future discovery there, even though the idea as presented by Doppler is basically incorrect’’. In 1846 Doppler published a better version of his principle where he considered both the motion of the source and the motion of the observer. Proof that Doppler’s theory was right was brought by the Dutch mathematician Ch. H. D. Buys Ballot (1817e1890) during a well known ‘train station experiment’ (1845). Doppler shift is in fact valid for any electromagnetic ( gamma, X-ray, ultraviolet, light, infrared, microwaves and RF signals) and acoustic waves (infrasound, sound and ultrasound).4 The life of C. Doppler‘s ideas is much longer than his own lifedand the next 160 years showed an increasingly broader band of (often unexpected) applications of his works.5 After Fizeau generalized the application of Doppler’s principle to light, astronomical studies have been decisively influenced. Relativistic form of the Doppler shift ( for objects travelling very fast) and Lorenz contraction correction allowed to approximate the speed of the Universe expansion and to define the ‘big bang’ timing. Extrasolar planet detection became possible: the planet tugs its star in a slight elliptical motion, which can be detected using the Doppler shift of the starlight.6 At the other edge, at the microcosmic level, for atomic spectra in the visible and ultraviolet light, Doppler broadening often sets the limit on resolution of spectroscopy. With the thermal motion, the atoms traveling toward the detector will have transition frequencies, which differ from those of atoms at rest by the Doppler shift. The distribution of velocities can be derived from the Boltzmann distribution.7 RADARS (radio detection and ranging)dfirst introduced by Robert Watson-Watt in 1935, use radio waves shift from moving reflecting/scattering atmospheric targetsdas different as low-earth-orbit (LEO) satellites, airplanes (aviation radars) or rain drops (weather radars). Radio direction finding systems and SAR (synthetic-aperture radar)d side-looking imaging systemsdrely on the same effect, while police radars use mainly microwave deflection for speed control. The ‘Doppler galaxy’ of our times includes the names of commercial companies, rock groups, hometown streets and even of a lunar crater, baptized in honor of the Austrian physicist. First ultrasound medical application (Dusik 1942) and first cardiac one (Edler 1953) were quite rapidly followed by the use of Doppler effect for flow characterization.8 Shigeo Satomura and Yasuhara Nimura at the Institute of Scientific and Industrial Research in Osaka, Japan (beginning with 1955) used it for the study of cardiac valvular motion and pulsations of peripheral blood vessels.9 A couple of years later, a Seattle-based pediatrician (R. Rushmer) assisted by a group of engineers (including D. Franklin, D. Ellis and Donald Baker) pioneered transcutaneous continuous-wave flow measurements and spectral analysis in peripheral and extracranial brain vessels (1958). Actually, with the introduction of pulse-Doppler (Baker-1970), transcranial continuous Doppler (Rune Aaslid-1982), color-Doppler, power-Doppler, tissue-Doppler imaging and many other developments, Doppler ultrasonography became e for decades e the main non-invasive His vision In 1846, C.A. Doppler wrote: ‘‘It is almost to be accepted with certainty that this (his theory) willdin the not too distant futuredoffer astronomers a welcome means to determine the movements and distances of such stars’’. Doppler could not have imagined the revolutionary effect of his discovery in various areas of human interest. We owe a lot to this man, whose 19th century work hasdso surprisinglyddeeply influenced present day cardiology. 10 instrument for functional assessment of heart and vessels. References 1. Grössing H, Kadletz K (Band 1), Schuster P (Band 2). Christian Doppler (1803e1853). Vienna: Böhlau Verlag; 1992. 2. Eden A. The Search for Christian Doppler. Vienna: SpringerVerlag; 1992. 3. Doppler CA. Über das farbige Licht der Doppelsterne und einiger anderer Gestirne des Himmels. Abh Königl Böhm Ges Wiss 1843;2:465e82. I.M. Coman 4. Filkin D, Hawking S. Stephen Hawking’s Universe: The Cosmos Explained. New York: Basic Books; 1997. 5. Heilbron JL, editor. Oxford Companion to the History of Modern Science. New York: Oxford University Press; 2003. 6. Hearnshaw JB. Doppler and Vogeldtwo notable anniversaries in stellar astronomy. Vistas Astronomy 1992;35: 157e77. 7. Ohanian HC. Physics (2nd ed. expanded). WW Norton & Co.; 1989. 8. Dussik KT. Uber die moglichkeit hochfrequente mechanische schwingungen als diagnostisches hilfsmittel zu verwerten. Z Neurol Psychiat 1942;174:153. 9. Satomura S. Ultrasonic Doppler method for the inspection of cardiac function. J Acoust Soc Am 1957;29:1181e5.