elamona, welcome a-board!
Light does NOT travel at the same speed all the time.
Correct. It propagates more slowly in non-empty space, and the denser the medium, the slower it propagates.
Massive stars and large collections of galaxies in "small" areas slow the speed of light.
Incorrect. The apparent "slowing" of the speed of light in this case is actually only a relativistic effect due to space-time curvature in the presence of gravitational fields. Einstein's General Theory of Relativity is based on a Riemannian curvature tensor (a relatively complicated but otherwise purely geometric mathematical expression) coupled with the Lorentz metric (which incorporates the postulate that the speed of light is a universal constant in empty space). The Schwarzchild solution of this tensor quantifies this relativistic "time" effect of light propagating by, or through, such curvatures...but the actual speed of light remains constant.
As do black holes, which stop light from escaping at all
Correct, but they don't change the speed of light. What happens is you reach a point where the curvature of space "makes" light travel in a circle (so to speak; technically called a "geodesic" line). This is called the Schwarzchild radius, and was mathematically predicted decades before it was actually observed.
Gravity affects the speed of light.
Incorrect.
I have been collecting all of the APOD's since NASA has been putting them out in 1995 and quite a few are Hubble pics showing the "bowing" or gravitational lensing effect on light in the vicinity of massive gravity fields.
Perfectly described by the equations above, as based on the constancy of the speed of light in empty space.
There is another physics lab, in England I think, that has slowed the speed of light to a couple of hundred miles /hr in their lab under artifical conditions.
What you're referring to here is the speed of light in a quantum-mechanical "super-dense" ultra-low-temperature medium:
http://www.sciam.com/article.cfm?articleID=000BAEB1-B2AA-1C6F-84A9809EC588EF21&pageNumber=1&catID=2
This effect has nothing whatsoever to do with the speed of light in empty space.
I don't intend my comments above to appear harsh (as if directed at you personally), but all the empirical and mathematical evidence to date points to only one conclusion: the speed of light in empty space is a universal constant, and has been so since the beginning of our physical universe. Any "young earth creationist" ideas to the contrary simply fly in the face of all known physical science.
Craig
