Summary of black holes (black holes )
If we could summarize in a few words what a black hole ( black hole in English) is a bounded region of the universe caused by the collapse ("death") of a massive star, and as main property it has a density so high that the gravitational force (the force that attracts objects with mass) does not allow even let light escape.
Star to consume nuclear fuel that way, especially hydrogen, transforms this hydrogen into heavier elements, first helium which in turn is converted into carbon and oxygen this and so on to form iron. In this process the gravitational force that contracts the matter ends up winning the nuclear forces that tend to expand the star and this ends up shrinking, gaining in density, ever going to have more weight in less space, while generating greater gravitational force . When there is nothing that can stop the process, begin to merge the components of atoms, first protons and electrons to give neutrone s and then these would merge to lead to asingularity of infinite density which we call black hole. In this process the star, its light becomes increasingly weaker, darker and disappear like the Cheshire cat, leaving only its gravitational force.
Not always the collapse of a star ends up in a black hole. In this struggle between nuclear forces and the gravitational force, the collapse can stop resulting in a white dwarf or a star beyond neutron star. In that process can be the star burst, ejecting the outer material and resulting in a nova or a supernova . This stellar explosion can occur very intense, so much so that can be seen with the naked eye as a point of intense light in heaven where there was a star with lower light intensity.
Returning to black holes, if we sent Roy Batty, the evil replicating Blade Runner to Cygnus X1 , and told us that he has seen the black hole and not we were going to believe, we should tell you that indeed we could not believe it because black holes can not be seen as neither could emit light can escape.
Is Universe gruyere cheese, the original Swiss cheese full of holes?
Black hole, Kerr black hole, black hole of Kerr-Newman black hole Schwarzschild black hole of Reissner-Nordstrom black hole, wormhole. More like, since none has been seen, which are solutions to mathematical equations without physical sense; mathematical illusions without correspondence with reality. Today, leaving aside other holes, black holes can only be inferred by what happens around given the extraordinary gravitational pull they exert on neighboring bodies on the stellar gas, stars and space around them.
Today we know of many things black holes, as they are born, how they grow, the size may have and how we can detect; but there is still debate in the scientific community about its structure and above all on an area called the black holeevent horizon . It also seems that the universe is full of horizons apparent, isolated, dynamic, ...
The event horizon is a closed surface that separates the region of the black hole, the singularity, the rest of the universe and is the boundary surface of the space from which no particle can leave, including photons. Even light with a speedy nearly 300,000 km per second can escape the gravitational pull of a black hole.
Hence a black hole is defined by two characteristics that we have seen, it has an event horizon and has a singularity;and provided that certain conditions in the equations that define these parameters are met is true the theory of general relativity.
In 1974 Stephen Hawking introduced quantum parameters to explain the singularity where the laws of physics can not say much about the system, which led him to say that black holes emit radiation, the famous Hawking radiation. But if emit radiation this can be detected and we evaporate the black hole as it is black holes emit not exist if something is then described.
Recently, 2014, Hawking posed in an article that can not speak of event horizons, but of apparent horizons, but recoverable chaotic radiation and has formed a mess. The subject seems complex, and physicists are at it, whether or not you can retrieve that information. Well as they say the physical and ending theme, black holes have become mathematical laboratory where trying to combine quantum mechanics with general relativity theory of Einstein.
While this happens, for the rest of us, black holes will remain one of the most fascinating places in the universe, mysterious and disturbing
Let us questions arise. Are there black holes? What are the equations that define them? Are there solutions that refuse? How do they form? What types are there? What is your size? ¿Emit some radiation as Hawking says. And so? Is there a black hole about us? How do we know? Is this poses a danger? If the universe was formed of a singularity by a huge explosion, the Big Bang, black holes are the precursors of universes?
Background on black holes
The term "Black Hole" was first used by a journalist, Ann Ewing, in 1964 to make a report of a meeting of the American Association of Advanced Science (American Association for the Advancement of Science) and write an article in Science News Letter entitled"Black Holes in Space" . A few days later, Albert Rosenfeld published in Life magazine that the gravitational collapse of a star can end in an invisible black hole in the universe. However, it is the American theoretical physicist John Archibald Wheeler , who popularized the term in a lecture given in 1967 at the University of Columbia, sets the term "black hole - black hole" when referring to what had been terming star continuous gravitational collapse.
Beyond the name, the concept appears much earlier. The English philosopher John Michell , in 1783, nearly 100 years after Newton wrote his law of universal gravitation, in a report to the Royal Society of London, mentions the idea that a massive body would not escape the light. A few years later, in 1796, the mathematician Pierre-Simon Laplace predicted their existence in the bookExposition du système du Monde , where he talks about black stars ( dark stars ).
In late 1915, Karl Schwarzschild found a solution to Einstein's equations, where a heavy body would absorb the light. He managed to define the distortion that the mass of a star produced in the space-time fabric. Albert Einstein in 1915 had developed the theory of general relativity which showed that light was influenced by the gravitational interaction.
Schwarzschild showed that when you approach a star, time is slowed by the action of the gravitational force of the same, even when you have gone through and has reached the center of it. The waves emitted in the vicinity of the star would have longer (or what is the same frequencies shorter) periods, then the starlight would see the red moving because it is the shortest frequency. Bringing to an end the situation where there is a critical density, the time would eventually stop and shoot the light frequency toward the red to finish canceling the spectrum leaving emit visible light. The limit where this occurs it is known as the Schwarzschild radius is now known and which corresponds to the radius of the event horizon of a black hole does not rotate, which was not well understood at the time.Schwarzschild and Einstein thought it was nothing more than a mathematical illusion without, physical real sense.
We must make a special mention to Karl Schwarzschild, and wrote his theories being in the trenches of the Russian front that I took his patriotic fervor in the Great War (World War 1).
Subrahmanyan Chandrasekhar , in 1930 showed that a body with a critical mass, (now known as the Chandrasekhar limit) and not emitiese radiation, would collapse under its own gravity because there would be nothing to be known that could stop it (for that body strength gravitational attraction would be greater than that provided by the Pauli exclusion principle , which basically amounts to saying that the electrons in an atom must be layered around the core, hence the atoms with more electrons have more volume). The gravitational force overcomes nuclear forces. However, most scientists opposed the idea that the star would reach zero size, implying a naked singularity of matter, and I should have something to put brake inevitably collapse.
In 1939, Robert Oppenheimer predicted that massive stars could undergo a gravitational collapse and therefore, black holes could be formed in nature.
Roy Kerr in 1963 solutions to the equations that reflect rotating black holes.
Stephen Hawking and Roger Penrose, in 1967, proved that in certain cases could not prevent a black hole be created from the collapse of a star and black holes are solutions to the equations of Einstein's theory of general relativity .The black hole idea gained momentum with scientists and experimental advances that led to the discovery of pulsars. In 1974 Hawking states that according to quantum mechanics black holes can emit radiation like a black body, which is called radiation Hawking.
In 2014 Hawking in a draft scientific paper states that one can not speak of event horizon if not apparent horizons where the information can exit a black hole would be chaotic but recoverable, which would change the way we know the holes black.
Theory of black holes
Black holes are a theoretical prediction of Einstein's General Relativity.
The special relativity Einstein had explained very well, among other things, that nothing can travel faster than the speed of light and that this was the same for all observers, which demonstrated with his experiment Michelson and Morley; but nevertheless it was inconsistent with the theory of gravitation of Newton , which says that objects with mass attract each other with a force that is dependent on the distance between them. This meant that if an object is moved immediately the force on the other change instantly. This led us to the paradox that the gravitational effects should travel at infinite speed instead of the maximum speed of light, since there is nothing faster than her.
To solve this paradox, Einstein proposed the theory of general relativity, a revolutionary argument " ... space-time is not flat, space - time is curved (deformed) by the distribution of mass and energy present in it ... " ; this indicated that gravity was a force different from the others.
For example the sun's mass curves space - time so that the Earth following a straight line in the four-dimensional space, in three-dimensional space is a circular orbit. The orbits of the planets predicted by general relativity theory are very similar to the orbits predicted by the theory of Newtonian gravity.
The light should be affected by the gravitational fields. This would mean that the light from a star passing close to an object with mass will be deflected through a small angle, if that what we observed from Earth would see the star is not in the position where it is in fact. In the right picture you can see the effect produced by the massive cluster Abel 1689 in the light of the most distant galaxies appears bent by the effect of the gravitational field of the cluster. This is calledgravitational lensing and were predicted by Einstein. In the case of a black hole deformation of space - time is such that not even light that falls into the same could escape.
Another prediction of the theory of general relativity is that time should elapse slower near a massive body and this is because the light energy is related to the frequency, the number of waves of light per second. This is to say that a person who was in a massive body on its surface, and the other was away, would age differently, for which the surface is in time would pass more slowly so it would age less. In the case of a black hole, where mass is critical, time would stop. Stephen Hawking and Roger Penrose showed that according to general relativity into a black hole must have a singularity of density and curvature of space - infinite time.
How do black holes form?
Gravity is attractive and tend to get to the star, while the star shines by nuclear reactions inside. These reactions star heat which increases the hydrostatic pressure in all directions, which compensates for gravitational attraction. If we thought in a balloon, nuclear reactions would be the gas that inflates the balloon surface and the gravitational force would prevent it from inflating.
Nuclear reactions produce more and heavier elements. Star to consume nuclear fuel that way, especially hydrogen, transforms this hydrogen into heavier elements, first helium which in turn is converted into carbon and oxygen this and so on to form iron. However, iron is stable and no fusion with another element releases energy.
While no nuclear fuel, nuclear reactions are able to compensate for the force of gravitational contraction, but when the spent nuclear fuel, gravitational force shrinks the star to the point where the electrons that make up the atoms cease to be free motion, and now depending on the mass of the star can stop the process.
If the mass of the star is not very big, there are still a force, which stems from the Pauli exclusion principle quefuerza electrons to be layered, which can stop the process if it is greater than the gravitational force forming a star dwarf White , as a white dwarf Sirius B accompanying the brightest star in the sky, Sirius A, seen from Earth, and that according to the data collected from the Hubble telescope has the same diameter (12,000 km) but the Earth the mass of the Sun, with a 350,000 times greater than Earth's gravitational force. A person of 68 kg on Earth would weigh 25 million kilograms in the surface of the star.
If the mass of the star is greater than 1.44 Mʘ (solar masses), the Chandrasekhar limit, the strength of electron degeneracy is not enough and the electrons and protons combine to give rise to neutrons, forming a neutron star. In this process the star explodes as a supernova remnant being composed mainly of neutrons and other particles, the baryon . By the same principle of Pauli, the collapse can be stopped because neutrons are fermionic particles , which like the electrons can occupy the same quantum state space and simultaneously. Add to that the strong nuclear force due to the baryonic particles adds.After then, the nuclear forces are greater than the gravitational force and the collapse stops.
A neutron star has total density of 3.7 × 1017 to 5.9 × 1017 kg / m3 (2.6 × 1014 to 4.1 × 1014 times the density of the Sun), with diameters of a few km and mass between 1.4 and 2.1 of the Sun. This density is roughly the mass of a Boeing 747 compressed into the size of a small grain of sand.
One example is the Crab Pulsar discovered in 1969 in the Crab Nebula as seen in the image by the Hubble and the Chandra X-ray telescope. A pulsar is a neutron star that rotates at high speed, in this case has diameter of 25 km and rotates 30 times per second.
If the star is a supergiant more than nine solar masses, the gravitational collapse will lead to a black hole, since there will be some who overcomes the gravitational pull force.
It is believed that black holes exist, such as the Milky Way that has been called Sagittarius A * (Sgr A *), located 27,000 light years from Earth in the center of galaxies. Rather close in terms of distances in the Universe. It is believed to have a mass of more than 3.7 million solar masses and occupies more than 45 AU (1 AU units astronómicas- the average distance from Earth to the Sun, 150 million km). In the picture the situation, their environment is not the black hole.
What types of black holes exist?
Werner Israel, showed that a black hole without rotation described by the equations of general relativity, it should be easy to describe, be spherical and depend only on its mass. The particular solutions of the Einstein equations for these black holes were discovered by Schwarzschild. A compliant holes that are not rotating and have no charge are calledSchwarzschild black holes.
Roy Kerr found a set of solutions to the equations of general relativity that described rotating black holes. These holes are called Kerr black holes .
In general terms we can say that anything that suffer gravitational collapse reaches a steady state as a black hole only described by three parameters: its mass, charge and angular momentum. Thus we have the following classification for the final state of a black hole and that includes the two types described above:
. The simplest possible black hole is, that has not broken or load Schwarzschild black hole.
. If not tour but has electric charge, there is the black hole called Reissner-Nordstrom.
. A rotating black hole without charge is a Kerr black hole.
. If you also possess charge, we speak of a black hole of Kerr-Newman.
By body type you can be classified into:
Supermassive black holes with masses several billion solar masses. They would be in the heart of many galaxies.
Stellar-mass black holes. They form when a star of mass 2.5 times that of the Sun goes supernova and implodes. Its core is concentrated in a very small volume every time is reduced more. This is the kind of black holes postulated for the first time in the theory of general relativity.
Micro black holes. They are hypothetical objects, somewhat smaller than stellar. If they are small enough, they can get to evaporate in a relatively short period by emitting Hawking radiation. This type of physical entities is postulated in some approaches to quantum gravity, but can not be generated by a conventional process of gravitational collapse, which requires the Sun above the masses.
What is Hawking radiation?
Stephen Hawking said his book "History of Time ..." is ... black holes are not as black ... - - . And why? He first postulated in 1973 that black holes at the event horizon could emit radiation. He described the properties of such radiation.
Russian scientists Yakov Zeldovich and Alexander Starobinsky Hawking suggested in 1973 that according to the uncertainty principle of quantum mechanics ( Heisenberg uncertainty principle ) rotating black holes should create and emit particles, although the math he endured they were weak, which Hawking handled accurately calculate that year.
One consequence of the uncertainty principle of quantum fluctuations are empty. These include the creation, for the briefest moment, particle / antiparticle pairs from the vacuum. These particles are "virtual", but the intense gravity of the black hole becomes real. Such pairs together disintegrate rapidly returning the borrowed energy for their formation. However, on the edge of the event horizon of a black hole, just outside the event horizon boundary of the black hole, the probability that a member of the pair is formed on the inside and one on the outside it is not null , so that one component of the pair could escape the outer boundary; if the particle escapes, the energy will come from there.
From the technical point of view, the reality is that this issue does not occur Hawking in the black hole but in the space just outside the event horizon. The final conclusion is that black holes should behave as warm bodies and therefore emit radiation but must come from the space immediately adjacent to the edge of the event horizon. In primitive supermassive black hole radiation emissions should be gamma rays and X-rays, which helped in the search for them when trying to detect this type of radiation.
Are there solutions to equations that deny black holes?
There is the relativistic theory of gravitation Logunov, very similar to general relativity in almost all aspects and which also explains the observed facts in the solar system and the universe's expansion. Use slightly different field equations.
Since the experimental data do not allow to discern which of the two theories (Einstein's general relativity and relativistic gravitation of Logunov) is correct, as both coincide for most observational facts well proven, could not give guaranteed that black holes are a necessary consequence of gravitation.
For isotropic vectors TRG predicts that inequality shall be satisfied:
and thus, typical of the theorems of Penrose and Hawking singularity of occurrence conditions are not met and the space-time will be free of them. And so black holes can not exist
In the theory of Logunov certain solutions to problems of the general theory arise, what would be an alternative, bringing solutions to mathematical equations to the following responses:
Predicts non-occurrence of black holes.
The conditions required by the singularity theorems are true and therefore free of these complications do appear in general relativity. This leads to that the universe began with a singularity. The Big Bang theory crumbles
Is there a black hole about us?
How do we know?
In the center of the Milky Way is a complex structure, with a great source of radio waves that seem to identify one of the supermassive black holes in the universe. A black hole into which scientists have called Sagittarius A * and which is in the constellation of the same name in the center of our galaxy, about 27,000 light years away.
The center of the Milky Way three elements overlap identified as Sagittarius A East , it seems the remnant of a stellar explosion, the remnant of a supernova. Another element isSagittarius A West , which is seen from Earth spiral structure with three arms and consists of ionized clouds of gas and dust that orbit around the center of the incredible speed of 1000 km per second. The center of Sagittarius A West is what is known as the third element, Sagittarius A * and is supposed to be the supermassive black hole.
The vision of the gas and dust clouds around the black hole in its range of X-ray and infrared allow to see as could be directed to where the hole and dropped into it. Another observation is the stars that orbit around it and they do it much faster than any of the stars seen in the galaxy. One of those stars is SO-2 having an elliptical orbit of 123 AU (astronomical units) around the black hole, and with the incredible speed of 5,000 km per second and a period of 11.5 years.
Another evidence found by scientists is issuing jets of high energy particles from Sagittarius A *.
A calculation that scientists have done is that the black hole would have a mass of setting 3.7 million solar masses and 45 AU in size, but still consuming material around so is growing.
In 2014 scientists think there is an opportunity to see the effects when a gas stream into the event horizon occur. In this year called G2 gas jet, and was far from the center of the black hole it is approaching at high speed (a speed doubled in the last year) the black hole by the great gravitational power of this
In the image taken by the European Southern Observatory you can see how the gas cloud is espaguetizando, stretching in the direction of the black hole and increased fivefold speed as it approaches.
Is there a danger in being so close in astronomical terms the black hole Sagittarius A *?
No nothing seems to happen even though it is estimated that its event horizon can be about 0.0006 light years. We are at a great distance 27,000 light years away. How far can the attractiveness of a black hole? It is assumed that its capacity would be infinite, but in terms of time would need almost an almost infinite time in terms of life on Earth. Let it not be for tomorrow.
Crossing the event horizon would not anything at that time according to the theory of relativity, for those who were outside and they would have gone for us because in terms of time near the black hole's gravity slows time , for each minute would pass over 1000 years on Earth. Once inside the force of gravity would be so intense and growing as we approach the center of the hole, we would end alongándonos from the feet to the head which spaghetti and disappear.
Are black holes the origin of other universes?
If according to the Big Bang theory (see Web) the universe emerged from a singularity where everything was a big explosion now 13,000 million years ago is it possible that black holes are the source multiverse? Increasingly, scientists think that our universe is not alone. So it could be a way to generate mass and taking other? How much mass is needed?What I would do that in a moment that explosion is created, the Big Bang? Questions unanswered for lack of evidence.
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