Black Holes have kept scientists and astrophysicists on their toes for decades now. These people are really scared of them, not because of what they do, but because they are so hard to find and to prove their existence in nearby universe. The only ones that have been found are either thousands or millions of light years away. Moreover if one could send a probe close enough to examine the Black Hole, it would be sucked into it in a fraction of a second.
Black Holes are the living symbols of the triumph of gravitational forces over every other force in nature. Small black holes are formed when huge stars collapse while the bigger ones require the whole centre of a galaxy to form. The centre of the Black Hole is a point of infinite gravity called a singularity. Black holes are considered to be rotating constantly and thus the singularity is thus stretched into a ring. Theoretically, it is possible to fall through this ring without any damage. But that is just a theory. The fastest thing in the universe- light , also can’t escape a black hole’s gravity so it is these massive light changes that are detected in order to locate black holes. There is a theory which supports the fact that our galaxy, the Milky Way, harbours in its centre a huge black hole. This has been proven by calculating the motion of stars in the centre of our galaxy.
Next up is another category of celestial bodies called the Quasars. Quasar itself stands for – quasi-stellar radio source. These are ultra-luminous objects generally found in the centre of a galaxy and they easily overshadow the luminosity of the galaxy in which they reside. The factor by which they outshine their parent galaxy is more than one hundred. But these quasars constantly change the luminosity by a factor of two and that too in just about a few weeks. Now this event throws light on the size of quasars. If the quasars were huge (about the size of a light year) then these luminosity variations from centre to the surface would happen every year but since this happen every few weeks, this proves that Quasars are only a few light week in size (which is quite small).
But the point is from where does this massive amount of light come? The brightest stars are able to convert only 0.1 % of their mass into energy and at the most 1% can be converted by the star. The light emitted by a quasar is greater than that of an entire galaxy. This property strongly support that quasars are fuelled by nothing but the light emitted by the matter falling into a black hole itself. When matter swirls around a black hole it can convert 30% of its mass into light before falling into the black hole and getting shredded. Therefore a conclusion can be drawn that black holes and quasars are interrelated to each other with most of the galaxies being dormant quasars.