The bending of light rays by the sun was one of the first evidences that Einstein's theory of general relativity (sometimes called his theory of gravity) was correct. Some people say that this theory abolished force. In Einstein's book *Relativity The Special and the General Theory* (authorized translation by Robert W. Lawson, copyright 1961 by the estate of Albert Einstein) we read:

*"As a result of this theory, we should expect that a ray of light which is passing close to a heavenly body would be deviated towards the latter… It may be added that, according to the theory, half of this deflection is produced by the Newtonian field of attraction of the sun, and the other half by the geometrical modification ("curvature") of space caused by the sun."*

Isn't the 'Newtonian field of attraction' a force? It is in my opinion. But what is it about the theory that predicted this force? It seems to me that since the beam of light is deviated **toward** the sun rather than away, that this rules out the 'saddle shaped universe' in favor of a 'spherical universe'. Excuse me for rambling; I'll get to the main point soon.

The book goes on to talk about the eclipse of 1919 (the experimental confirmation). It has a table listing several stars with the observed and the calculated for the first co-ordinate and the second co-ordinate (in seconds of arc). To have a calculated amount there must have been an estimate of the sun's mass before. How was that estimate made? Since there is an observed amount, the mass of the sun should be able to be calculated from the observation (the main point). Can anyone tell me the formulas to do that?

Now the next question that a metrologist would ask is which measurement is better. I wonder if cosmologists are using GR measurements for the sun's mass.

## Comments rated to be Good Answers:

Re: Can the Sun be weighed using General Relativity?" by Codemaster on 04/02/2008 4:55 AM (score 2)