A javelin graduated in centimeters is thrown downwards from the top of a tower of height h. Initially the centimeter marks pass an observer at the top of the tower with frequency f, speed s and "wavelength" L (1cm):
f = s/L
What are the frequency f', speed s' and "wavelength" L' as measured by an observer on the ground? Newton's theory gives a straightforward answer (it is assumed that s>>s'-s):
f' = f(1+gh/s^2) = (s+v)/L s' = s(1+gh/s^2) = s+v L' = L
where v=s'-s is the increase in speed.
Then the observer at the top of the tower emits light towards the ground. Relative to this observer, the light has frequency f, speed c and wavelength L:
f = c/L
What are the frequency f', speed c' and wavelength L' as measured by an observer on the ground? Newton's emission theory of light gives a straightforward answer again:
f' = f(1+gh/c^2) = (c+v)/L c' = c(1+gh/c^2) = c+v L' = L
where v=c'-c is the increase in speed. The Pound-Rebka experiment confirmed the predictions of Newton's emission theory of light:
http://www.einstein-online.info/spotlights/redshift_white_dwarfs Albert Einstein Institute: "One of the three classical tests for general relativity is the gravitational redshift of light or other forms of electromagnetic radiation. However, in contrast to the other two tests - the gravitational deflection of light and the relativistic perihelion shift -, you do not need general relativity to derive the correct prediction for the gravitational redshift. A combination of Newtonian gravity, a particle theory of light, and the weak equivalence principle (gravitating mass equals inertial mass) suffices. (...) The gravitational redshift was first measured on earth in 1960-65 by Pound, Rebka, and Snider at Harvard University..."