The two telescopes surveyed a pair of relatively small patches of sky, one in the Northern Hemisphere and one to the south. Chandra's southern view covered an area about the size of the full Moon as it appears from Earth. Presumably what we're seeing in these two patches is typical of the rest of the sky. Extrapolated to the whole sky, he said this would amount to 200 million of the objects throughout the early universe. Black holes everywhere Black holes are massive objects that cannot be seen.
Scientists theorize their existence based on the effects they have on their surroundings.
The most notable effect is gravity. A black hole's tremendous mass is concentrated in an infinitely small space, and they exert incredible gravity on surrounding matter and energy. Once in the grip of a black hole, nothing can escape, not even light. Supermassive black holes at the centers of galaxies are often actively gobbling stars and gas in mass quantities. Tremendous energy is created as this matter swirls inward and approaches the speed of light.