search on NASA site also go through the latest news related to black holes before presenting your seminar.
many queries are asked related to black holes.
present the astronomical data's for Good delivery of seminar.In the 18th century John Michell and Pierre-Simon Laplace first mentioned about the objects with a huge gravitation, from which even light cannot escape.
In 1915 Albert Einstein developed the theory of general relativity.
Karl Schwarzschild finds black holes as a solution to Einstein’s equations (1916)
Robert Oppenheimer and Hartland Snyder predict that massive stars can collapse into black holes (1939)
A black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull.”
Black holes are exotic structures whose gravitational fields are so powerful that they trap everything, even light. They were first postulated by Albert Einstein's theory of general relativity.”
This can happen when a star is dying.
Though they are black they are invisible to us.
The density of a black hole is so great it would be like taking the whole Earth and crushing into a volume smaller than a 1” marble!.
Stellar-mass: 3 to 20 times the mass of our Sun
Supermassive: Black holes with millions to billions of times the mass of our Sun
Mid-mass: In between stellar-mass and supermassive.