AFAIK black holes are factual, but i can not find physical proof of the singularity, apart from Einstein's theory of general relativity, which showed that when a massive star dies, it leaves behind a small, dense remnant core. If the core's mass is more than about three times the mass of the Sun, the equations showed, the force of gravity overwhelms all other forces and produces a black hole. http://science.nasa.gov/astrophysics/focus-areas/black-holes/ Scientists can't directly observe black holes with telescopes that detect x-rays, light, or other forms of electromagnetic radiation. They can only infer them by other other means We can, however, infer the presence of black holes and study them by detecting their effect on other matter nearby. My question is how do we know apart from the theory of relativity that the singularity exists.?