Nasa has a good site that they answer questions on also. http://helios.gsfc.nasa.gov/qa_gp_ls.html I have asked them as well as posting a question on Facebook’s NASA site.
They state that magnetic fields can manipulate light in a vacuum. I have asked them if anyone has done any experiments on whether radiation would do the same thing. I am just a hobbyist and my interest peeked in this stuff after trying to write a computer simulation on a black hole.
The interesting thing for me would be that this could explain dark matter as well. Since we would have Radioactive Matter effecting lensing and non Radioactive material that would then become the equivalent to the elusive “Dark Matter” I make this jump since I believe they use gravitational lensing to determine the mass of a galaxy. If this is true the lensing effect’s equation would need to be re-written as an effect of radiation.
Wow I was way off here. Great site here describes what is actually going on http://www.lacosmo.com/DeflectionOfLight/index.html I was wrong to interpret the light as bending away. It is actually bending toward the mass.