Okay, I can not answer mathematically but I will answer with reasoning, do not judge me very hard, since I have asperger and I had to leave school at age 13 for bullying, first of all I do not contradict Albert Einstein, it is true That space- Time folds to the center of the planets. I think that dark matter is directly related to space-time, therefore light travels through space-time-dark matter, according to my theory the space-time-dark matter travels to the center of the planet to become electromagnetic waves, this generates a Constant flow. In short, to answer your question, nothing is derived, the calculation is the same.