Gravity vs. Light

What is the attraction effect of gravity on light? There are three possibilities. Either light is attracted to mass by means of gravity, or it is repelled by mass, or there is no effect. But almost all scientists say that light, like any other particle is attracted to mass. For example, if you have a black hole, light and matter is sucked into the black hole, but no light can escape because of the enormous gravitational pull. So if light is travelling in the vicinity of a body of mass, what effect will this attraction have on the light? I see two possibilities. Either gravity will cause the light to speed up/slow down, depending on the light's direction with respect to the gravitational pull, or the light will be stretched out. Being that we are told that light moves at a constant speed, this only leaves the option of light being stretched. It would not matter which direction the gravitational pull is coming from. All gravitational pull from all directions would stretch the light out. If an object is trying to move at a constant rate, and a force is pulling at it from behind, or pulling at it from the front, the net effect will be the same. In order to maintain it's desired speed, pressure will be put on it to stretch out in order to counteract the pulling force. So if I am correct in my assumptions, it means that all light between stationary objects will tend to be red shifted due to gravity, and the amount of red shift will increase as the distance travelled ("age") increases. Assuming a homogeneous universe, the stretching effect could be calculated, but if the light travelled in a non-homogeneous area of space where the gravitational pull was stronger or less, then the effect could not be calculated unless the gravitational pull was known for each region of space the light travelled through.So, if gravity is affecting the red shift of light in this manner, then the cause of the high red shifts of distant galaxies may be due to gravity and thus there is no proof that the universe is expanding.

No, I'm not referring to "Tired Light". I've done a little more research on this since I posted that and found that what I was trying to express is called the Shapiro Effect and it has evidently been proven to exist. See http://www.geocities.com/newastronomy/Shapiro.htm for more information on this. I am no physicist, so perhaps my thoughts and words to express those thoughts were not exactly perfect. I will try to research more about the Shapiro Effect and see what experiments have been done to prove or disprove if its effects could be enough to accont for all the redshift we are seeing.

Well, according to the website, the gravitational pull due to the Shapiro Effect decreases with the inverse of the logarithm of distance, not the inverse of the distance. And this has supposedly already been verified by observations of the Mariner spacecrafts. If true, it would mean that gravity would still have an effect even at much greater distances.I don't quite see your point about the correlation of time for particles with mass and the light. The gravity is affecting the light after it has left the emitter and continues to affect it as it travels through empty space, just as the expansion of the BBT is affecting the light as it travels through space. Neither of these effects on the redshift have anything to do with the light as it being emitted from the source. So I fail to see how you could distinguish which of these two possibilities caused the redshift based on particles being emitted by the supernova. The gravity strength of the source may affect the redshift slightly as the light is being emitted, but I would think this effect would be minimal and is not what the Shapiro Effect refers to. Any further information on this correlation or a link to a site falsifying the Shapiro Effect would be appreciated.One more thing to consider, is that if the Shapiro Effect is something to be reckoned with, and if the BBT is also considered correct, then the Shapiro Effect could have a drastic effect on how we interpret certain observations. For instance, if we use the current estimates of the expansion rate as being correct, it would mean the universe is much younger than what most cosmologists say it is. Furthermore, any observations of events early in the formation of the universe would be even more profoundly influenced by gravity due to the universe being much more compact at that time and thus a much larger Shapiro Effect. So in this case, the whole model of the universe would likely fall apart because there wouldn't be enough time for the universe to develop as we see it. But, on the other hand, with the Shapiro Effect it would mean that the expansion rate could be much less to achieve the redshifts that we observe, and this would give us a much older universe.

So if the Shapiro Effect is impossible, then gravity is not affecting the redshift of light. But doesn't that violate Einstein's Theory of Relativity where he observed that gravity does affect light when it leaves the surface of the source and causes loss of energy and thus a redshift? I find it hard to believe that gravity does not affect the light to at least some degree as it is travelling through space, the only question in my mind is how much. I will continue to try to research this and see if I can find some good verifiable data which shows how much of an effect it will cause.