What is a black hole, how it is formed and other curiosities

Black holes are some of the most fascinating and yet unexplored formations in outer space that have kept scientists and researchers on edge since they were discovered. Here we explain what a black hole is and how it is formed.

What is a black hole?

To define what a black hole is, in a few words we could say that it is a region of outer space where nothing, not even light , can escape its gravitational pull. It is an area in space-time where gravity is very strong and does not allow the smallest particles, electromagnetic radiation and space objects such as comets and planets to enter.

Because nothing can get out of these spaces, they are not visible to people , which is why they are known as black holes. Space telescopes with special tools are used to identify them.

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The theory of general relativity , which was published by Albert Einstein in 1915 and which describes gravitation in modern physics, predicts that a sufficiently compact mass can warp spacetime which then turns into a black hole. The boundary of the black hole after which nothing can escape its gravitational pull is called the event or event horizon.

According to the general theory of relativity, black holes have no detectable characteristics even though they can have a huge impact on the objects around them . Stellar-mass black holes have temperatures on the order of one billionth of a kelvin, making them impossible to observe.

History of black hole research

Now that you know what a black hole is, we will go on to summarize the history of the investigation of these formations.

In the 18th century, John Michell and Pierre-Simon Laplace were the first to consider black holes as objects whose gravitational pull was strong enough not to let even light escape. Later, in 1915, Einstein developed the general theory of relativity and showed that gravity influences the movement of light.

For his part, Karl Schwarzschild , in 1916, discovered a solution using the theory of relativity to identify what a black hole is. Later, in 1958, David Finkelstein studied it further. The discovery of neutron stars in 1967 sparked greater interest in gravitationally collapsed compact objects.

On February 11, 2016, LIGO Scientific Collaboration (LSC) and Virgo detected gravitational waves for the first time. It also represented the first observation of a black hole merger.

In December 2018, 11 gravitational wave events spanning 10 merging black holes were observed and in April 2019, the first direct image of a black hole and its surroundings was published. The observation was made using the Event Horizon Telescope that in 2017 served to glimpse the supermassive black hole located at the galactic center of Messier 87.

Curiosities about black holes

In early 2015, researchers from Peking University discovered one of the largest black holes 12.8 billion light-years from Earth . This means that the light surrounding the black hole began its journey to Earth less than a billion years after the Big Bang.

Today, scientists continue to study these space wonders, but we already know some curiosities about black holes.

What is the size of a black hole?

Scientists believe that the smallest black hole is the size of an atom, but its mass can reach the size of a giant mountain . In our Milky Way there are several stellar black holes that are 20 times bigger than the sun . The largest are called supermassive and have masses of more than 1 million suns together.

How are black holes detected?

Scientists detect them through strong gravity, which affects surrounding objects like stars and planets. Researchers study the behavior of stars and other objects to find out if they are close to a black hole. Also, high-energy light is emitted when a black hole and a star are close together . These lights can be identified using powerful telescopes.

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Black holes were stars in the past

Stars live a long time, but like us, they don’t live forever. They slowly burn the fuel that keeps them so bright.

When they are depleted, one of three things happens, mainly depending on their mass (which is the amount of matter they contain): it can transform into a white dwarf star, a neutron star, or a black hole.

If the star is big enough (about 10-15 times bigger and heavier than the sun), it will explode when it comes to an end. The explosion causes the star to collapse in on itself , making it much smaller. Because the size of the star gets smaller, but its mass does not, the gravity surrounding the star becomes so strong that it absorbs everything around it, including light. This is how a black hole is born .

There are 3 types of black holes

These are the types of black holes that exist:

  • Black microholes : they are considered the smallest. Its size ranges from that of a single atom to that of a mountain.
  • Stellar Black Holes – These are the most frequently encountered. They are about 20 times bigger than the Sun.
  • Supermassive Black Holes : The black hole discovered in 2015 falls into this category. To be in this group, the hole has to be more than a million times heavier than the Sun.

Not seen with the naked eye

No matter how much you look up at the sky, you will never be able to catch a glimpse of a black hole!

The reason black holes are so black is because they consume everything around them , including light. This is because the gravitational pull at its center is very strong.

But without reflection, we have nothing that can detect the hole directly. For this reason, scientists look for the traditional effects that a black hole has on its environment.

When a star is inserted into the hole, it breaks and becomes distorted . As it’s sucked in, chunks of matter from the star move faster, create intense heat, and give off an X-ray glow. That’s what astronomers can use to identify a hole .

Black holes help create galaxies

Astronomers are still not entirely sure what role black holes played in creating galaxies. But one of the theories is that a large star exploded, a black hole formed, and the rest of the galaxy was created around it .

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There is a black hole in the milky way

Did you know that our own galaxy has a black hole in the center known as Sagittarius A * ? In fact, scientists believe that there is a supermassive black hole at the center of almost all galaxies .

Because the pull of a black hole is so strong, you might be wondering if the Earth is in danger of being sucked into a supermassive black hole. You don’t have to worry yet, as Sagittarius A *, the Milky Way’s black hole, is 26,000 light-years from Earth .