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Black Hole

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In outer space , a star is usually the center of a solar system and nearby planets revolve around it. Sometimes a star is compressed in such a way that it can transform into a black hole. Although these are invisible to us, scientists can observe how those planets of a solar system revolve around nothing.

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What is a black hole?

It is an area of ​​space where gravity is so strong that even light cannot escape. Therefore, it appears black . They are formed when a supergiant star collapses or when two large stars collide. The gravitational force is of such magnitude that it absorbs the elements that are around it.

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Definition of black hole

A black hole is defined as a finite region of space , in which its interior there is a concentration of mass so great and dense that it generates a gravitational field so high that no particle can escape from it, not even light , engulfs what it is around him in a kind of bottomless hole.

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Characteristics

  • It is a body with such a dense mass that not even light can escape from it.
  • In some supermassive holes , through certain telescopes , dust can be seen to be absorbed at high speeds.
  • They emit radiation .
  • Its severity is very high.

History

  • The English geologist, John Michell , was the one who first mentioned the existence of an object so dense that not even light could escape from it. Such an idea was found in an article that was sent to the Royal Society in 1783 .
  • In 1915 , the development of the theory of general relativity by Albert Einstein confirmed the influence that gravitational interaction has on light .
  • Later, the absorption of light by a heavy body was demonstrated. The credit went to Karl Schwarzschild , who in 1916 verified the equations created by Einstein.
  • For his part, the famous physicist Robert Oppenheimer and his group of students, predicted in 1932 that a star with a great mass could undergo a gravitational collapse and give rise to a black hole , a fact that would finally be proven.
  • In 1963 , Roy Kerr demonstrated the quasi-spherical geometry in all black holes, based on their total electric charge e , their angular momentum L, and their mass.
  • Stephen Hawking and Roger Penrose , verified in 1967 that black holes were solutions to the equations proposed by Einstein.
  • In 1969, the term black hole was first mentioned by John Wheeler. Previously, it was known as a gravitationally collapsing star .
  • In the 1970s, several theorems about black holes were proven, especially their shape and occurrence. The credit went to Hawking, Penrose and George Ellis. In addition, Hawking found that black holes emit radiation.
  • A team of researchers led by Andrea Ghez , from the University of UCLA in 1995, verified the existence of supermassive black holes at the center of galaxies. The finding was made by computer simulation .
  • In 2008 experiments were carried out to measure the black hole that exists in the center of the Milky Way , Sgr.A (or Sagittarius A). In them, it was determined that it was not very active because it would have consumed a large part of the matter found in its immediate gravitational field .

Types

They can be divided in two ways:

According to the mass

  • Micro black holes: Their solar mass is less than the sun, they are a hypothetical black hole that evaporates in a relatively short time through the emission of Hawking radiation.
  • Stellar: They are generated when a star implodes and dies . They usually have a mass of more than 3 solar masses.
  • Intermediate: They usually have a mass between 100 and 1,000,000 solar masses. They are located in the middle of the stellar and the supermassive. It is a hypothetical type since although indications have been found, there is no direct evidence .
  • Supermassive: They are usually found in the center of galaxies and have masses between 1,000,000 and tens of billions of solar masses.

According to its physical properties

  • There are black holes that have charges and do not rotate ( Reissner-Nordstrøm black hole ). On the other hand, some have no charge and no rotation ( Schwarzschild’s black hole ).
  • In addition, there are holes that have rotation and charges ( Kerr-Newman black hole ), while others rotate but do not have charges ( Kerr black hole)

Parts of a black hole

The basic elements of a black hole are:

  • Gravitational singularity : It is an interior zone of space-time where the physical magnitudes related to gravitational fields cannot be defined.
  • Event horizon: It is the imaginary spherical surface that surrounds the black hole . It has a gravitational force so strong that for an object to move away its escape velocity must be similar to the speed of light.
  • Schwarzchild radius: indicates that the larger the black hole, the more mass will be absorbed towards it. Used to measure spherical and static black hole ( Schwarzchild black hole )
  • Accretion disk: it is a structure composed of gas and stellar dust that has a disk shape. It is created by the gravitational force of massive objects that attracts other objects, thus achieving their expansion.
  • Ergosphere: is the outer region that surrounds the event horizon. It is rotated next to the black hole dragging spacetime.
  • Gas jet : they are the jets of matter that are related to the accretion discs. They are formed due to matter with excess angular momentum

Other elements that make up a black hole are:

  • Accretion stream
  • Place of danger
  • Windy disc
  • Dust disc
  • Breeding line clouds
  • Cold gas disk
  • Hot turbulent disc
  • Quasi-periodic source of oscillation
  • Intimate stable circular orbit
  • Hot central wind
  • Vortex
  • Re-collimation wave
  • Gamma ray emission region
  • Microwave and radio emission region.

How a black hole is formed

It is formed when the hydrogen and helium fuel of a star is consumed, causing a supernova that sometimes due to the enormous gravitational force can turn into a black hole.

Moreover, the stars of neutrons , they can also turn into black holes. The smallest are believed to have formed when the universe was created. Finally, supermassives may have originated at the time galaxies were created.

How does it work

It works similar to how a vacuum cleaner would in space. Its gravitational force is so great that it attracts other elements that surround it and in this way it becomes larger and larger. As it absorbs the material and it is consumed due to friction , which produces radiation and energy leaks known as jets.

What’s inside a black hole

Although it is not yet known for sure that it contains the interior of a black hole, according to Albert Einstein’s theories we know that they contain a singularity, where the density of matter in relation to gravitational fields are infinite. It is thought that it may contain other universes or matter absorbed through time.

If someone were to enter a black hole, the difference in gravity would turn it into a spaghetti, every molecule , cell and atom would be attracted by the tidal force.

How to detect a black hole

Scientists use X-ray telescopes to detect them, since as Stephen Hawking showed , they generate large amounts of radiation, due to the surface loss of matter from objects that are sucked into the black hole. Also, they can be detected by noticing the effect on the bodies that surround the black hole.

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