I don't think that is completely accurate. It is said that gravity can have an effect on the speed of light and time. The speed of light, as Einstein once put it, is relative as well as time. If you were traveling on a beam of light at the speed of light, other beams of light would appear to stand still, or travel slow. Also, a clock that is at the top of a tall building would appear to run faster than clocks near ground level. There is one very important thing to remember is that God created light before He created the sun, moon and stars. He also created evening and morning before creating the sun, moon and stars (Genesis 1:3-5). Some Young Earth Creationist like to argue that light was created in transit. I don't think that is true but it is interesting to consider that light was created before these celestial bodies were. What do you think???