Editing Christian Doppler (section)

=== Development of the Doppler effect ===
[[File:Doppler's Birth House.jpg|thumb|right|Doppler's birth house in the Makart square in [[Salzburg]], just next door to where [[Wolfgang Amadeus Mozart|Mozart's]] family had lived. A Doppler research and memorial society is now housed there.<ref>{{cite web|url=http://www.visit-salzburg.net/sights/christiandoppler.htm|title=Visit Salzburg – Christian Doppler birthplace|website=www.visit-salzburg.net}}</ref>]]
[[File:Christian Doppler österreichischer Physiker.jpg|thumb|right|Plaque on the house in [[Prague]] in which Doppler lived from 1843 to 1847]]

In 1842, at the age of 38, Doppler gave a lecture to the Royal Bohemian Society of Sciences and subsequently published ''[[Über das farbige Licht der Doppelsterne und einiger anderer Gestirne des Himmels]]'' ("On the coloured light of the binary stars and some other stars of the heavens").<ref name="AlecEden">{{Cite book
| last = Eden
| first = Alec
| title=The search for Christian Doppler
| publisher=[[Springer-Verlag]]
| location=Wien
| year=1992
| isbn=978-0-387-82367-6 }}</ref> In this work, Doppler postulated his principle (later named the [[Doppler effect]]) that the observed frequency of a wave depends on the relative speed of the source and the observer, and he later tried to use this concept to explain the visible colours of [[binary stars]] (this hypothesis was later proven wrong). Doppler also incorrectly believed that if a star were to exceed 136,000 kilometers per second in radial velocity, then it would not be visible to the human eye.<ref>{{Cite book |last=Lequeux |first=James |url=https://www.worldcat.org/oclc/1164698750 |title=Hippolyte Fizeau : physicist of the light |date=2020 |isbn=978-2-7598-2188-4 |location=Les Ulis |pages=32 |oclc=1164698750}}</ref>