Hey, this is my first post. Just talking about an idea I had. A month ago I was pondering the effects gravity has on light. Specifically if there could be a “gravitational red-shift” of light coming from massive stars. I first started by thinking of gravity as simply causing an object, which lets say was moving away from an object, to have an acceleration toward the object. And of course it would eventually come to a stop and reverse direction. Another way of thinking about this is that the object loses momentum to the object its attracted to (atleast this is what I thought then). Recently in my physics class (AP Physics B) we had used an equation that would tell you the momentum of a photon. I started thinking that if a photon had momentum then why wouldn’t it, like a particle with mass, slowly stop and reverse direction when moving away from a gravity well? First I remembered that light would always move at the same speed in vacuum and thought that something else might happen instead of slowing down, because it didn’t seem right. So I thought it was possible that light could lose momentum without slowing down, it would simply lose energy or decrease it’s wavelength. But this would mean that there where no “true” black holes because then it would mean that black holes could emit photons, although the photons would be red-shifted to nearly an infinite wavelength. This didn’t seem right either. I was about to forget the whole thing and give up when I remembered that gravity was suppose to slow down time, a concept that at the time I didn’t believe in. Then I realized that thinking of light, and any other objects, losing momentum as they fell into a gravity well was completely wrong. If time where to slow down then to an observer at a distance away from a gravity well it would seem that photons would be traveling at less than the speed of light when coming from the gravity well (assuming he knew when the photon left). This could explain how a photon could not be gravitationally red-shifted. If you think about it, this could be thought of as analogous to what happens to light as it goes from one optically dense material to another. The velocity and wavelength of light changes as it passes though different mediums. Its like moving into more optically dense mediums as you get closer to the center of the gravity well, just assuming that the change in optical density is infinitesimal. This would explain things like gravitational “lensing.” So as far as I can figure light can’t really be gravitationally red-shifted because although wavelength changes so does the velocity, and the frequency does not change. So really the light never loses any energy (or momentum) from gravity and therefore gravitational red-shift doesn’t exist. After thinking about it for a while I realized that no object loses momentum from gravity if you think about it. Just thought this might interesting. Tell me if I’m right or just someone trying to understand things out of his league.