The Math Forum

Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Math Forum » Discussions » sci.math.* » sci.math

Replies: 3   Last Post: May 2, 2013 2:30 AM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Pentcho Valev

Posts: 4,982
Registered: 12/13/04
Posted: Apr 30, 2013 3:57 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply
American Journal of Physics, Volume 32, Issue 1, pp. 52-55 (1964): "Gravitational redshift of photons from a star and gravitational bending of the path of photons grazing the sun can be derived by using only Newton's laws and the idea of a photon as a particle of mass hv/c^2. The difference between the relativistic and Newtonian equations for gravitational redshift is too small to be detected and, therefore, gravitational redshift does not provide experimental verification of the general theory of relativity."

That is, the shift in frequency is caused by the shift in the speed of light in a gravitational field, as predicted by Newton's emission theory of light. It can be shown that, if the speed of light varies with the gravitational potential as predicted by the emission theory (c'=c(1+gh/c^2)), then, in gravitation-free space, it varies with the speed of the observer again in accordance with the emission theory (c'=c+v):
"The light is perceived to be falling in a gravitational field just like a mechanical object would. (...) The change in speed of light with change in height is dc/dh=g/c."

Integrating dc/dh=g/c gives:

c' = c(1 + gh/c^2)

Equivalently, in gravitation-free space where a rocket of length h accelerates with acceleration g, a light signal emitted by the front end will be perceived by an observer at the back end to have a speed:

c' = c(1 + gh/c^2) = c + v

where v is the speed the observer has at the moment of reception of the light relative to the emitter at the moment of emission. Clearly, the speed of light varies with both the gravitational potential and the speed of the observer, just as predicted by Newton's emission theory of light.

Pentcho Valev

Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© The Math Forum at NCTM 1994-2017. All Rights Reserved.