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Black Holes are regions or points in space that have such strong gravity that nothing can escape from it. These points are dense to the extent that they create a deep gravity sink. Even light cannot escape from the Black Hole. In case any object, whether it is a spacecraft or planet, comes near the black hole, it would be compressed and stretched. This process is referred to as spaghettification. In 1958, David Finkelstein was the first to publish his views about the black hole as a region from which nothing can escape.
Basics of Black Holes
A black hole is formed when a massive star collapses after its life cycle. Once it has been formed, the black hole absorbs mass from its surroundings. Black holes can absorb other stars too and can merge with other black holes. This gives rise to supermassive black holes. There are four types of black holes that can be formed.
- Stellar mass black holes
The most common way in which a black hole is formed is when a massive star reaches the end of its life and then implodes. This makes the star collapse in on itself, and when the core cannot stop this implosion, it forms a black hole.
- Intermediate mass black holes
This is a rare type of black hole. It is formed when more than one stellar mass black holes merge with each other. Usually, they happen in parts of the galaxies that are crowded. Repeated mergers can give rise to such huge black holes.
- Supermassive black holes
When many intermediate mass black holes merge with each other, they form a supermassive black hole. When this happens, the black hole can be a million times the mass of the sun. It is believed that these black holes are formed through a chain reaction of colliding stars.
- Primordial black holes
A primordial black hole does not exist but is a hypothetical type of black hole. Theoretically, there were many tiny points in space rich in energy. Their collapse could give rise to black holes whose mass could be less than a paperclip or thousands of times more than the sun.
History
It was Albert Einstein who first predicted black holes in 1916 when he formulated the famous general theory of relativity. It was John Wheeler who was responsible for coining the name ‘black hole’ in 1967. The first black hole to be spotted was in 1971. The first image of a black hole was recorded in 2019. The Event Horizon Telescope was able to spot a black hole in the center of a galaxy known as M87. They then released this image, which was the first ever.
More about Black Holes
There are three layers in a black hole. They are:
- The event horizon
- The inner horizon
- The singularity
The event horizon is the boundary of the black hole around the mouth. This is the area beyond which light does not escape. The event horizon area is where gravity is constant throughout.
The inner horizon is the inner layer beyond which lies the singularity of the black hole.
The singularity is the core of the black hole. It is the point in space and time where the entire mass is concentrated. Any object entering the singularity will be spaghettified.
While astronomers can see stars and other objects easily, it is not so easy to see black holes. They need to look for the radiation emitted when gas and dust are drawn into the singularity. There are also cases where objects, instead of being pulled into the black hole, are pushed away if they bounce off the event horizon. This causes bright jets that travel at relativistic speeds. These can be spotted in space even though the black hole is not visible.
Each black hole is different
All black holes are not the same, and each one differs from the others. The tiny black holes are theoretical, while supermassive black holes exist at the centers of galaxies. Sagittarius A* is the black hole located at the center of our Milky Way galaxy. Black holes can keep growing, feeding on dust and gas from objects that come close.
While the belief is that the black hole is like a vacuum cleaner that sucks everything into it, this may not be exactly true. Any object must be really close to the black hole to get pulled into it. This is best illustrated by the fact that even if our sun was replaced by a black hole, none of the planets would get sucked into it.
