Black Holes are mysterious objects which are located throughout the universe. They are commonly known and widely debated by theoretical astronomers as "gravitic anomalies- in which matter enters, but does not leave. They are sources of gravity that are so strong, not even light can escape its powerful pull. They have been studied by famous intellectuals such as Stephen Hawking and Albert Einstein. They have been described as "worm holes- to other dimensions, as well as the "final frontier."" It is something which we can not know about, and it stirs our curiosity and makes us search even harder for answers. In recent years astronomers, astrophysicists, and a curious, if somewhat bewildered, general public have witnessed a number of exciting developments that Robert M. Wald claims "has shaped our ideas of space, time, and gravity."" Part of this "reshaping of ideas- comes through new innovations in the detection of Black Holes.
The earliest means of detection, and the one responsible for locating the most black holes, has come from observing binary systems which contain one. In these systems there is a normal star in a close orbit with another body which is not seen optically. The existence of the second body is inferred from the periodic Doppler shift of the spectral lines of the visible star (Wald 111). The unseen body was cause of speculation, and evidence of its true nature was first found in 1970. Between 1970 and 1977, when satellites which could detect X-rays were first orbited, about ten X-ray sources have been identified with binary star systems (Wald 112). These orbiting satellites could detect intense energy which can only come from one place. Stellar material from a companion star, swirling toward the edge of a black hole, is compressed and superheated, causing it to radiate in intense X-ray streams, an energy that space observatories can detect and measure. The binary X-ray source which has received the greatest attention as a candidate for a black hole is Cygnus X-1.