I do not that that the speed of light is constant. Light slows down when passed through water. Black holes are not really my things. The speed of light and it's intensity are. Gravity also plays a key factor in your search. When the Feild Thoery is completed we may all have our answers. We already know that matter and energy are one and the same. Electromagnetic force sets up a magnetic feild and a magnetic feild sets up a electromagnetic force all with the aid of motion. Electromagnetic force can also set up light and the other way around. Not much is known about gravity. Is it a feild, curved space or both? Everything flip flops. Where does gravity fit in? It must be the same but so far I know that the intensity of gravity and the intensity of light obey the same law, maybe also the intensity of a magnetic force. Remember that gravity is the key here. Black holes have lots of gravity and affect time around them to the best of our information. What I'm looking for at the moment is the flip flop of gravity and I don't mean anti-gravity. GOT ANY IDEAS?