Date: Aug 20, 2011 1:45 PM
Author: h.jones
Subject: Einstein's factor of 2 in starlight deflection
Einstein's original formula for deflection of light skimming the Sun's

surface breaks down to 2GM/Rc^2. This is merely the Schwarzschild

radius divided by current radius of the Sun. If all things are

considered to be happening at the rate of c and at the Schwarzschild

limit the reckoning gets easier. Then R/R=1, that is one radian, in

terms of angle and one radius in terms of length or distance. You

could say it is an equivalence of distance measured in terms of

radius. All that considered look at it this way:

If we consider that at the Schwarzschild limit, whatever the star's

mass or radius, then in that particular frame the star's mass becomes

the local timescale mass and its diameter becomes the local time

frame. Take the case of the Sun at ,say, 2x10^30kg, radius at

2.9690906x10^3m and thus its local c at 2r, 5.9381812x10^3m. The time

unit here,then, will be 1/5.0485569x10^4 of a second. Looking at this

numerical principle, consider the following.

The formula for free fall, distance travelled, is (gt^2)/2, where g is

gravitational acceleration and t is time in local time units. If g=c

then we could look at the formula as (ct^2)/2. The formula for g is

GM/r^2, so we could look at it like this: {(GM/r^2)t^2}/2. If we

consider time to be one single unit there is no need to include it. So

our formula becomes (GM/r^2)/2. But we need to put everything in

terms of c and radius is equivalent to c/2. So our formula can be

adjusted again to: (4GM/c^2)/2 which breaks back down to 2GM/c^2.

Therefore, the formula 2GM/c^2 means the same thing as (gt^2)/2 where

g=c and refers to length or distance not angle.