Re: gravity and the bending of space

Hello, Jason –

You are correct that the mass of the object does not matter; however, its 
speed certainly does! If I throw a ball horizontally, it falls to the 
Earth within a few meters (ball-throwing is not one of my skills). If I 
fire a bullet horizontally, it goes very much farther before landing 
(indeed, it goes so far that it probably runs into something else first). 
Light is, of course, traveling with an extremely high velocity; the 
gravitational warping of space-time deflects it only a little. Indeed, a 
light beam is the definition of a straight line; its bending is the 
minimum that could be caused by the given gravitational environment. 
Everything else, being slower, will bend more.

This gravitational bending of light was predicted by Einstein’s general 
theory of relativity; its measurement at approximately the predicted 
value, during a solar eclipse, was one of the first confirmations of the 
theory.

Here is a Web page about tests of general relativity:

Tests of General Relativity
 http://www.drphysics.com/syllabus/GRTest/GRTest.html

And here are some other references about gravitational bending of light, 
including gravitational lensing:

Light Bending
 http://phyun5.ucr.edu/~wudka/Physics7/Notes_www/node100.html

Gravitational Lenses
 http://astro.hi.is/lens/adal_th.html

The Principle of Equivalence
 http://www.emory.edu/PHYSICS/faculty/benson/380/notes/9/9.html

Space, Time, and Gravity
 http://www-astronomy.mps.ohio-state.edu/~pogge/Ast162/Unit5/gr.html

The Abell 2218 Cluster, a beautiful example of gravitational lensing
 http://tycho.bgsu.edu/~laird/cp_images/abell_2218.html

A lengthy exposition of Newtonian, special, and general relativity:
 http://etext.lib.virginia.edu/cgi-local/DHI/dhiana.cgi?id=dv4-12