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| | Doppler Shift |
 | | Christian Johann Doppler (probably Döppler; 1803-1853) probably had such double stars in mind when he wrote in 1842 that perhaps the difference in colors were due to the motion of the stars, since the frequency of the light from an approaching star should be increased, and from a receding star decreased. |
 | | The optical Doppler effect was not observed until 1905, when J. Stark found that the light emitted by canal rays, which are fast ions from the cathode of a glow discharge, was Doppler-shifted by the expected amount. |
 | | The red shift of the light from distant galaxies is also famous, and is usually interpreted as due to a recessional velocity increasing linearly with distance, though the argument is in danger of being a circular one. |
| www.du.edu /~jcalvert/phys/doppler.htm (2886 words) |
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