hat the particles do not come from within the black hole, but from the empty space just outside the black holes event horizon (Ferris 231).Since black holes are invisible, astronomers have been trying to locate them by observing their effects. Black holes have tremendous gravitational pull, matter and light particles around them are attracted towards the center. As matter and light particles approach a black hole they form a swirling accretion disc, like water going down the plunghole of a bath, with gas piling up and getting hot as gravitational energy is converted into energy of motion(Gribbin and White 137). When light enters a violent spin under strong gravitational pull, it emits rapidly pulsating and detectable X-rays. In 1965 astronomers observed intense X-rays coming from the constellation Cygnus (nearly 10,000 light years away). When satellite technology was born, in 1971, the world's first X-ray satellite pinpointed the exact location of these X-rays. It was found to be a massive but invisible object that astronomers have named Cygnus X-1. Since Cygnus X-1 exhibit all the hypothetical properties of a black hole, there is a strong belief that Cygnus X-1 might be the first identified black hole (Gribbin and White 138). At present time, the Hubble Space Telescope provides us with images that prove the existence of black holes. The Figure 2 shows a recent picture taken by the Hubble Space Telescope of a nearby galaxy, which has a massive black hole. Figure 2.Astronomers have obtained an unprecedented look at the nearest example of galactic cannibalism - a massive black hole hidden at the center of a nearby giant galaxy that is feeding on a smaller galaxy in a spectacular collision. Such fireworks were common in the early universe, as galaxies formed and evolved, but are rare today (The Space Telescope Science Institute).During the second half of the 20th century, due to scientific effort and new satellite technology, research has ...
