Stars are affected by two main forces: Nuclear fusion, and graVItation Black Holes are the result of an Imbalance of these two forces, Nuclear fusion- the outward force from the star‘s centre and gravitation- the force pulling inwards. These two processes balance one another until all the star‘s hydrogen is exhausted, allowing gravitation to take over. Once gravitation dominates. the star becomes unstable and starts to collapse, As the core compresses, it heats up and results in a supernova explosion in which the material and radiation blasts out into space.
if what remains of the star is greater than 3 times the mass of our sun, it will continue to collapse and form a black hole. Relation to General Relativity Albert Einstein’s theory of general relatwity suggests that the most densest and massive objects conceivable, such as black holes, have gravity that is so strong that nothing, not even light, can escape their grasp.
I do not fully understand Einsteins general theory of relativity but lrn going to try and give everyone a very basic understanding of Why Einstein thought space and time are not separate but closely connected known as space-time.
When we describe the position of a flying plane We can use length, Width and height these make up the three dimensions of space. But another dimension can be used time, these four dimensions make up spacertime, The fundamental aspect of general relativity is effect that matter. With a graVItational field, has on the curvature of space, rather on the four dimensional spacertime, One way to Visualise Einsteins View of graVIty was to think of the rubber sheet analogy described in many texts, In order to understand this, consider a sheet of rubber, With a weight placed on it, to represent a star.
The weight Will form a depression in the rubber, causing the sheet near the star to be curved, rather than flat.
If one now rolls marbles on the rubber sheet, their paths will be curved. rather than being straight lines. so why have I gone on about general relativity and space-time. Because its the main theory used to describe why black holes have the effect they do on their surroundings. Consider the rubber sheet example again except this time a heavier but more condensed weight is put on top. This makes a huge depression in the sheet resembling the effect that a large mass Will have on the curvature of space-time. Nothing that astronomers/physisists know of can escape falling into a stationary. non-rotating (a.k.a Schwarzschild) black hole. Once going past the event horizon even light itself is cannot escape. In 1919, Einsteins theory was confirmed during a total eclipse of the sun.
The image of several stars behind the sun had shifted so that they were visible to astronomers on earth, The Event Horizon is the gravrty field of a black hole where the spacetime is so bent that light cannot escape it. Therefore we cannot see beyond the event horizon, because according to Einstein nothing can exceed the speed of light. in other words the escape velocity from the event horizon must be greater than c the speed of light. Thus when something enters the event horizon, it Will vanish without a trace. The Singularity According to the General Theory of Relativity the Singularity is a point of infinite space time cun/ature. This means that the force of gravity has become infinitely strong at the center of a black hole.
Everything that falls into a black hole by passing the event horizon, including light, will eventually reach the singularity of a black hole. Belore something reaches the singularity it Is torn apart by intense gravttational forces. Even the atoms themselves are torn apart by the gravitational forces Schwarzschild Radius Schwarzschild Radius Rs = ZMG/cz M stands [or massG is Newton’s constant coefficient of gravity, 6.67 x lO-llc is the speed of light‘ 3 x 108 The Schwarzschild Radius is the distance that defines the size at which an object such as a star becomes a black hole. If an object collapses to within its Schwarzschild radius. it becomes a black hole The radius is named after German astronomer Karl Schwarzschild, who derived the first model of a black hole in 1915‘