A black hole is an area in space where the gravitational field is so strong that it prevents even light from escaping.
The concept of such an enormous object that light could not escape was first suggested, in 1783, by geologist John Michelll (1724-1793) and the term “black hole” was the idea of theoretical physicist John Wheeler in 1967.
Scientists hold the hypothesis that black holes are generated when a massive star dies and its mass falls or implodes at a proportionately smaller point in space.
A black hole is formed when a body of mass M contracts to a size smaller than its gravitational radius, making the escape velocity equal to the speed of light.
According to the theory of relativity, nothing can travel faster than light. In this way, everything that is on the border border of the black hole, “the event horizon”, drags in the light and the surrounding matter.
A black hole is not visible to the naked eye because gravity literally devours light. Scientists manage to identify a black hole in space when they find stars whose behavior is affected by massive gravitational forces indicating that it is near a black hole.
The gravity in a black hole is strongly concentrated due to the large amount of mass accumulated in an extremely small space. It is as if, for example, we put in a small room the entire mass of the Sun. The room can contain the mass but does not prevent it from generating gravitational waves affecting its surroundings.
First image of a black hole
In 2019, the Event Horizon Telescope (EHT) project managed to capture, for the first time in history, the image of a supermassive black hole and its shadow in the Messier 87 galaxy.
The EHT project, of planetary scale, connected 8 radio telescopes around the world, more than 200 scientists, 5 billion gigabytes of information and, after 3 years of research, has managed to capture the first evidence of what until now was only a theory, beginning with the theory of relativity of Albert Einstein.
The first photograph of a black hole and its shadow is important because it confirms theories, as well as showing how matter behaves around the black hole. In this way, new discoveries about the behavior of the universe are possible.
Another of the great achievements that this image gives us is the creation of an algorithm capable of integrating a quantity of information that until that moment was impossible. We owe this great advance to Katie Bouman, an engineer in electronics and computer science.
Types of black holes
Black holes can be of different sizes. Scientists divide them into 3 sizes:
- Small: black holes the size of an atom but with the mass of a mountain,
- Stellar: black holes that contain masses equivalent to 20 times the Sun. These are the most common black holes in our galaxy: the Milky Way or Milky Way.
- Supermassive: they are black holes that contain masses equivalent to more than 1 million times the Sun. It is believed that every great galaxy has in its center a supermassive black hole. The supermassive black hole in the center of the Milky Way is called Sagittarius A and the analogy of 4 million soles is made in a ball.