I think nowadays, We are all aware of what a Black Hole is?......Ain't we?....Alright, after reading this post I am sure that you will completely understand about Black Holes.
First of all, the definition : A black hole is a region of space-time from which nothing, not even light, can escape. Now, that's a classy definition of a black hole. But what is it actually and what would it be like?
The theory of general relativity predicts that a sufficiently compact mass will deform space-time to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that marks the point of no return. It is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics. I think now you might have got an idea 'bout this whole matter. Black Holes are some of the few bodies in our universe that have so strong gravitational pull.......in fact in our knowledge the strongest gravitational pull, that even light cannot escape. But after all how are they formed out in the space and how do they survive?
Black holes are generally formed when a star, say 20 times the mass of our own sun collapses due to its own gravity. One point to note is that, the existence of a star is due to a delicate act of balancing between its own internal gravitational force which tends to crush the star and the nuclear energy generated by the process of nuclear-fusion inside the star which tends to blow the star apart. When such a star, completes its life cycle i.e burns out all of its fuel which are mainly Hydrogen & Helium, it has nothing left to balance it against the enormous force of gravity, so it starts to collapse. Generally, the star collapses, but it mass remains the same and volume almost decreases to zero and in turn its density tends to infinity.
At the center of a black hole as described by general relativity lies a gravitational singularity, a region where the space-time curvature becomes infinite. For a non-rotating black hole this region takes the shape of a single point and for a rotating black hole it is smeared out to form a ring singularity lying in the plane of rotation. In both cases the singular region has zero volume. It can also be shown that the singular region contains all the mass of the black hole solution. The singular region can thus be thought of as having infinite density.
The defining feature of a black hole is the appearance of an event horizon—a boundary in space-time through which matter and light can only pass inward towards the mass of the black hole. Nothing, not even light, can escape from inside the event horizon. The event horizon is referred to as such because if an event occurs within the boundary, information from that event cannot reach an outside observer, making it impossible to determine if such an event occurred.
As predicted by general relativity, the presence of a large mass deforms space-time in such a way that the paths taken by particles bend towards the mass. At the event horizon of a black hole, this deformation becomes so strong that there are no paths that lead away from the black hole.
The simplest black holes have mass but neither electric charge nor angular momentum. These black holes are often referred to as Schwarzschild black holes after Karl Schwarzschild who discovered this solution in 1916. According to Birkhoff's theorem, it is the only vacuum solution that is spherically symmetric. This means that there is no observable difference between the gravitational field of such a black hole and that of any other spherical object of the same mass. The popular notion of a black hole "sucking in everything" in its surroundings is therefore only correct near a black hole's horizon; far away, the external gravitational field is identical to that of any other body of the same mass.
Solutions describing more general black holes also exist. Charged black holes are described by the Reissner–Nordström metric, while the Kerr metric describes a rotating black hole. The most general stationary black hole solution known is the Kerr–Newman metric, which describes a black hole with both charge and angular momentum.
Once a black hole has formed, it can continue to grow by absorbing additional matter. Any black hole will continually absorb gas and interstellar dust from its direct surroundings and omnipresent cosmic background radiation. This is the primary process through which supermassive black holes seem to have grown (One of this is situated at the center of our galaxy, Milky way). Astrophysicists searching for black holes thus have to rely on indirect observations. A black hole's existence can sometimes be inferred by observing its gravitational interactions with its surroundings. Thus, it is clear that Black Holes are one of the strangest object in outer-space.
It has many deep and dark secrets in it, waiting for it to be explored. If anyone out there is interested in going inside the black hole, provided you have the required technology, contact me because I will be more than happy to join you!! That's All. Enjoy!!
First of all, the definition : A black hole is a region of space-time from which nothing, not even light, can escape. Now, that's a classy definition of a black hole. But what is it actually and what would it be like?
The theory of general relativity predicts that a sufficiently compact mass will deform space-time to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that marks the point of no return. It is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics. I think now you might have got an idea 'bout this whole matter. Black Holes are some of the few bodies in our universe that have so strong gravitational pull.......in fact in our knowledge the strongest gravitational pull, that even light cannot escape. But after all how are they formed out in the space and how do they survive?
Black holes are generally formed when a star, say 20 times the mass of our own sun collapses due to its own gravity. One point to note is that, the existence of a star is due to a delicate act of balancing between its own internal gravitational force which tends to crush the star and the nuclear energy generated by the process of nuclear-fusion inside the star which tends to blow the star apart. When such a star, completes its life cycle i.e burns out all of its fuel which are mainly Hydrogen & Helium, it has nothing left to balance it against the enormous force of gravity, so it starts to collapse. Generally, the star collapses, but it mass remains the same and volume almost decreases to zero and in turn its density tends to infinity.
At the center of a black hole as described by general relativity lies a gravitational singularity, a region where the space-time curvature becomes infinite. For a non-rotating black hole this region takes the shape of a single point and for a rotating black hole it is smeared out to form a ring singularity lying in the plane of rotation. In both cases the singular region has zero volume. It can also be shown that the singular region contains all the mass of the black hole solution. The singular region can thus be thought of as having infinite density.
The defining feature of a black hole is the appearance of an event horizon—a boundary in space-time through which matter and light can only pass inward towards the mass of the black hole. Nothing, not even light, can escape from inside the event horizon. The event horizon is referred to as such because if an event occurs within the boundary, information from that event cannot reach an outside observer, making it impossible to determine if such an event occurred.
As predicted by general relativity, the presence of a large mass deforms space-time in such a way that the paths taken by particles bend towards the mass. At the event horizon of a black hole, this deformation becomes so strong that there are no paths that lead away from the black hole.
The simplest black holes have mass but neither electric charge nor angular momentum. These black holes are often referred to as Schwarzschild black holes after Karl Schwarzschild who discovered this solution in 1916. According to Birkhoff's theorem, it is the only vacuum solution that is spherically symmetric. This means that there is no observable difference between the gravitational field of such a black hole and that of any other spherical object of the same mass. The popular notion of a black hole "sucking in everything" in its surroundings is therefore only correct near a black hole's horizon; far away, the external gravitational field is identical to that of any other body of the same mass.
Solutions describing more general black holes also exist. Charged black holes are described by the Reissner–Nordström metric, while the Kerr metric describes a rotating black hole. The most general stationary black hole solution known is the Kerr–Newman metric, which describes a black hole with both charge and angular momentum.
Once a black hole has formed, it can continue to grow by absorbing additional matter. Any black hole will continually absorb gas and interstellar dust from its direct surroundings and omnipresent cosmic background radiation. This is the primary process through which supermassive black holes seem to have grown (One of this is situated at the center of our galaxy, Milky way). Astrophysicists searching for black holes thus have to rely on indirect observations. A black hole's existence can sometimes be inferred by observing its gravitational interactions with its surroundings. Thus, it is clear that Black Holes are one of the strangest object in outer-space.
It has many deep and dark secrets in it, waiting for it to be explored. If anyone out there is interested in going inside the black hole, provided you have the required technology, contact me because I will be more than happy to join you!! That's All. Enjoy!!
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