Definition
BLACK HOLES are massive stars with huge attracting force, when anything
moving with speed V passing near such stars, its path bends around these type
of stars, such that if the distance is Ro it circulate around it and if it has smaller
radius, obviously it will be absorbed by that star. These types of stars are
the most elementary Black Holes. Especially when V=C, light also cannot escape
from these stars. Calculating this radius using centrifugal force, will result to an optimum radius
Also, if an object is going to escape from a star (assume zero size one) with initial velocity of light then the distance traveled L is a function of time
A = G×M / L2 Acceleration due to gravity of mass M
Even though L is a function of time, but this equation should have real roots, so the following condition will arise for condition of no-real-root or impossibility of escape of that star.
Ls = 1/2 × G × M / C2 (Schwarzchild Radius)
Black Holes are stars so massive that nothing can escape from them.
The above calculations are done with assumption that time is not variable, with a variable time all calculations which are not precise, and the above results are approximations of real values.
It will be discussed later that Black Holes show some type of emission.