black hole, in astronomy, celestial object of such extremely intense gravity that it attracts everything near it and in some instances prevents everything, including light, from escaping. The term was first used in reference to a star in the last phases of gravitational collapse (the final stage in the life history of certain stars; see stellar evolution), by the American physicist John A. Wheeler.
Gravitational collapse begins when a star has depleted its steady sources of nuclear energy and can no longer produce the expansive force, a result of normal gas pressure, that supports the star against the compressive force of its own gravitation. As the star shrinks in size (and increases in density), it may assume one of several forms depending upon its mass. A less massive star may become a white dwarf, while a more massive one would become a supernova. If the mass is less than three times that of the sun, it will form a neutron star. However, if the final mass of the remaining stellar core is more than three solar masses, as shown by the American physicists J. Robert Oppenheimer and Hartland S. Snyder in 1939, nothing remains to prevent the star from collapsing without limit to an indefinitely small size and infinitely large density, a point called the "singularity.
At the point of singularity the effects of Einstein's general theory of relativity become paramount. According to this theory, space becomes curved in the vicinity of matter; the greater the concentration of matter, the greater the curvature. When the star (or supernova remnant) shrinks below a certain size determined by its mass, the extreme curvature of space seals off contact with the outside world. The place beyond which no radiation can escape is called the event horizon, and its radius is called the Schwarzschild radius after the German astronomer Karl Schwarzschild, who in 1916 postulated the existence of collapsed celestial objects that emit no radiation. For a star with a mass equal to that of the sun, this limit is a radius of only 0.9 mi (1.5 km). Even light cannot escape the black hole but is turned back by the enormous pull of gravitation.
It is now believed that the origin of some black holes is nonstellar. Some astrophysicists suggest that immense volumes of interstellar matter can collect and collapse into supermassive black holes, such as are found at the center of some galaxies.
The origins of the super-massive black holes which concludes how they were formed and what caused them to form is an unsolved problem which is yet a mystery of astrophysics. ( Millis 2014)
Black holes were originally thought to have only mere mathematical concepts. There was seemingly no possible way to compress any object into a space small enough to equal to its schwarzschild radius. Later however, astronomer Subrahmanyan Chandrasekhar calculated that stars much larger than our own sun should theoretically be able to collapse into a black hole (UTFC). A star is like a blown up balloon with the force of gravity trying to compress the balloon inwards and the air trying to push the balloon outwards. Likewise, stars are held in balance by gravity trying to collapse the star inwards going against the outwards pressure of the internal reactions of the star called nuclear fusion. If the star is big enough and the pressure inside quickly disappears, gravity would and should slingshot the star into a tiny point with near infinite density with an extremely strong gravitatio...
Starting with black holes, Khalili describes the creation of one. I found that a black hole is what remains when a massive star dies. Because stars are so massive and made out of gas, there is an intense gravitational field that is always trying to collapse the star. As the star dies, the nuclear fusion reactions stop because the fuel for these reactions gets burned up. At the same time, the star's gravity pulls material inward and compresses the core. As the core compresses, it heats up and eventually creates a supernova explosion in which the material and radiation blasts out into space. What remains is the highly compressed and extremely massive core. The core's gravity is so strong that even light cannot escape. This object is now a black hole and literally cannot be seen because of the absence of light. Because the core's gravity is so strong, the core sinks through the fabric of space-time, creating a hole in space-time. The core becomes the central part of the black hole called the singularity. The opening of the hole is called the event horizon. Khalili describes that there are two different kinds of black holes:
...f gas, which collapsed and broke up into individual stars. The stars are packed together most tightly in the center, or nucleus. Scientists believe it is possible that at the very center there was too much matter to form an ordinary star, or that the stars which did form were so close to each other that they coalesced to form a black hole. It is argued that really massive black holes, equivalent to a hundred million stars like the Sun, could exist at the center of some galaxies
gravity and you end up with no star at all. The final one is the
Karl Schwarzschild is credited with being the brilliant astronomer who developed the concept of black holes. In 1916, using Einstein's general theory of relativity, he began to make calculations about the gravity fields of stars. He concluded that if a huge mass, such as a star, were to be concentrated down to the size of an infintessimal point, the effects of Einstein's relativity would get really fairly extreme. Schwarzschild doubted that a star could get that small, and theorized that if a star did infact shrink upon itself like that, its gravity would remain the same and the planets revolving around it would remain in the same orbits they always had. Since then however, some of Schwarzschild's theories have been disproved, but most of his initial theories hold intact today. The Schwarzschild Radius, the maximum radius a body with a specific mass can have that won't let light escape, is named in his honor, and the equation of which is still in use today: Rs=2MG/(c^2)
The idea of Black Holes was first proposed in the 1700s by scientists John Michell and Pierre-Simon Laplace, who argued, independant of each other, that there might be objects in the universe with such a large gravitational force, that even light could be trapped. Published in 1916 Einstein’s theory of general relativity which included how gravity does affect light’s motion, gave way to scientific discoveries involving black holes. In Einstein’s own theory, he was only able to approximate the solutions to some of his own equations, however Karl Schwarzschild was able to provide the solutions. These solutions described objects like black holes that had such massive density that nothing could escape them. Schwarzschild theorized that if an object had such a small radius, that the escape velocity will be greater than the speed of light. Because as previously mentioned, nothing is faster than the speed of light, the object would be sucked into itself by it’s own gravitational pull, which would cause the object to disappear. What r...
Before I begin to speak about black holes, I will have to explain what the white glowing specks in the sky are. Without a star a black hole could not be formed. In the beginning of a star life a hydrogen is a major part of its development. Stars form from the condensation of clouds of gas that contain hydrogen. Then atoms of the cloud are pulled together by gravity. The energy produced from the cloud is so great when it first collides, that a nuclear reaction occurs. The gasses within the star starts to burn continuously. The hydrogen gas is usually the first type of gas consumed in a star and then other gas elements such as carbon, oxygen, and helium are consumed. This chain reaction of explosions fuels the star for millions or billions of years depending on the amount of gases there are.
The whole idea of time and black holes has been questioning scientist and many common people for decades. Whether or not the theories provided make it physically possible to allow us to ever use any type of a black hole to an advantage? Technology over these past years has allowed us to learn more and more about what black holes are and what they can do. While also allowing ourselves to discover new possibilities that they might bring forth to greater innovations in our near future. But we can only imagine, through our knowledge and technology, what a black hole could do for us, due to all the dangers they bring forth.
...e times the mass of the sun. In this case gravity is overwhelmingly strong and is able to crush the neutron star towards zero mass. The result is a black hole with a gravitational field strong enough to not even let light escape (Brusca, 2004).
After a supernova, the core is likely to travel someplace else within space. When the core is less size than about 5 solar masses, the neutrons will halt the collapse of the star. This will create a Neutron Star. Neutron stars are observed as pulsars or X-ray binaries. When the core is very large, nothing that h...
Astronomers believe that most galaxies consist of a supermassive black hole at the center, which attracts all constituents of galaxies such as, dust, gases (mainly Hydrogen and Helium), atoms, stars, interstellar clouds and planets to the center by force of gravity, but are not sure whether all galaxies contain a black hole in the center. Galaxies keep moving in relative motion to one another and intermittently can come so close that the force of gravitational attraction between the galaxies may become strong enough to cause a change in the shape of the galaxies, while in exceptional cases, the galaxies may collide. If two galaxies collide, they may pass right through without any effect or may merge, forming strands of stars, extending beyond 100,000 light years in space (World Book Online Reference Centre, 2005). Hence, neighboring and often other colliding galaxies induce the sha...
Initially, Albert Einstein was the person to predict the existence of black holes through his General Theory of Relativity, in which he had created several general equations that show the interaction of gravitation as a result of space being curved by matter or energy. In 1915, he published Einstein’s field equations, which specify how the geometry of space and time is influenced by whatever matter and radiation are present, and form the core of Einstein's general theory of relativity (Redd). The general theory relativity was the initial step in the process to finding out more information about black holes. As time went on, there were a few main contributors that solved these equations to help develop better theories on black holes. One of the most important contributors to the development of a better u...