After all, it is not easy to believe that scattered rays of any kind can differ in frequency and wavelength from the primary rays. If you whistle in front of a barn door, the echo you get back sounds just the same as the sound that goes out…
1564 - 1616
1803 – 1882
1854 – 1900
1942 – 2016
1928 – 2014
1835 – 1910
1869 – 1948
1884 – 1962
1898 – 1963
1929 – 1993
1879 – 1955
1809 – 1865