How are Black Holes Formed
- [Working together as a “virtual telescope,” observatories around the world produce first direct images of a black hole = the supermassive black hole at the heart of the Messier 87 galaxy. The Event Horizon Telescope (EHT)]
- Types and Origins of Black Holes?
Black holes come in a variety of sizes, and their size depends on how much matter (their mass) is in them. Some are the remains of collapsed giant stars. A star has to be much larger than our sun to be a black hole. These types of black holes are only a few miles wide. Black holes have also been found at the centers of some galaxies. These black holes are so large that they contain an amount of matter equivalent to 100 million or more suns. These types of black holes are millions of miles across.
Is there a black hole at the center of our galaxy? Yes, there is a very large black hole at the center of our galaxy. It has a mass of about 3 million suns and is very far from Earth, about 24,000 light-years away. Massive black holes are thought to exist naturally at the centers of most large galaxies, and many have been discovered. The black hole at the center of our galaxy is too far away to be any danger to Earth.
How black holes form depends on their type and origin. So far, scientists have managed to define at least four different types:
- micro/small black holes
- middle black hole
- stellar black hole
- supermassive black hole
- How are Black Holes Made?
Current theories suggest that small or miniature black holes (some as small as atoms) may have formed in the earliest moments of the universe. So far, these tiny black holes have been purely theoretical and thought to be tiny dark vortices that spread across the universe.
These tiny black holes are thought to have masses of hundreds of solar masses.
Like miniature black holes, intermediate black holes are only really known in theory. These types of black holes are hundreds of thousands of solar masses, not millions or even billions of solar masses like their larger cousins.
Some scientists believe that the intermediate black hole is formed by the merger of miniature black holes. Others believe that, if they do exist, they would have formed from the collapse of stars hundreds of thousands of times as massive as our own sun.
Needless to say, the field has little consensus on these mysterious black holes.
Stellar black holes (roughly 20 or more the size of our sun) are created when massive stars collapse themselves.
"In their final stages, massive stars explode in massive explosions called supernovae. Such explosions fling the star into space, but leave the stellar core behind. While the star is still alive, nuclear fusion produces the external driving force," - National Geographic.
If this mass collapsed into an infinitesimal point, it would create a black hole—many times the mass of our sun. There may be thousands of these stellar-mass black holes in our own galaxy.
Supermassive black holes (equivalent to a billion or more the mass of our sun) are thought to have formed at the same time as the galaxies they inhabit, and are predicted by Einstein's general theory of relativity. At the center of the Milky Way is a supermassive black hole, Sagittarius A* (pronounced "ay star"), which is more than four million times the mass of the sun.
- What's Inside a Black Hole?
A recent study published (February 2022) in the journal PRX Quantum sought to find out what might be inside a black hole and came up with an intriguing theory that sounds like it might come from a sci-fi movie.
According to their theory, black holes may just be holograms. The study took a closer look at the concept of holographic duality, which has become popular to better understand black holes by linking the theory of particles and their interactions with the theory of gravity.
The holographic duality says that the theory of gravity and the theory of particles are mathematically equivalent.
Enrico Rinaldi, a research scientist at the University of Michigan, hopes that these two theories will lead to a better understanding of what's actually going on inside black holes.
"In Einstein's general theory of relativity, there are no particles -- just spacetime. In the Standard Model of particle physics, there is no gravity, just particles," Rinaldi said. "Linking these two different theories is a long-standing problem in physics -- something people have been trying to do since the last century."
