It is now 150 years ago, on 25th May 1842, that the son of a Salzburg ston emason presented a scientific work "On the coloured light of the double stars and certain other heavenly bodies" at a meeting of the Royal Bo hemian Society of Sciences held in Prague. Christian Andreas Doppler, then professor at the Prague Technical Institute, set a milestone in scien tific history in the meeting room of the Royal Society in the Charles Uni versity, just a few meters from the National Theatre where another genius from Salzburg, Wolfgang Amadeus Mozart, had celebrated his musical triumph with the...