Black holes are celestial objects predicted by Einstein over 100 years ago, but it wasn’t until 2019 that humanity captured the first actual image of a black hole. This image was of the black hole at the center of the galaxy M87 (Messier 87), located approximately 54 million light-years from Earth.
This supermassive black hole, situated at the center of a relatively nearby galaxy, has a mass 6.5 billion times that of the Sun, whereas the mass of Sagittarius A*, the black hole announced in 2022, is only 4.4 million times that of the Sun.
The supermassive black hole located at the center of a relatively nearby galaxy named Messier 87, or M87, is about 54 million light-years from Earth (1 light-year is the distance light travels in one year, equivalent to about 9.5 trillion kilometers). (Image: Space).
Astronomers currently believe there are primarily two types of black holes in the universe: firstly, stellar black holes, which are formed from the collapse of a star’s core after a massive star dies, with masses ranging from tens to hundreds of times that of the Sun.
The second type is supermassive black holes found at the center of each galaxy. Their masses range from millions to billions of times the mass of the Sun. There are approximately two trillion galaxies in the observable universe; thus, astronomers believe there are also two trillion supermassive black holes.
Currently, the total mass of all stellar black holes and supermassive black holes is roughly equivalent to 1% of the total mass of the universe, indicating that 1% of the universe has been consumed by black holes.
Previously, the scientific community believed that supermassive black holes in the universe originated from the collisions and mergers of stellar black holes, as there are many old massive stars at the centers of all galaxies. When these stars become black holes, they merge under the influence of gravity into larger black holes, which, given enough time, can lead to the formation of supermassive black holes.
The universe’s black holes are believed to form when a massive star dies. After the star’s nuclear fuel is exhausted, the star’s core collapses into a state of matter denser than 100 times that of an atomic nucleus, so dense that protons, neutrons, and electrons are no longer discrete particles. (Image: Zhihu)
However, with discoveries of supermassive black holes billions of light-years away made by the Webb telescope, the hypothesis of merging stellar black holes into supermassive ones has become untenable.
In the early days of the Big Bang over 10 billion years ago, our universe had only a few stars, which were not enough to form supermassive black holes, suggesting that there are other causes explaining the origin of these supermassive black holes.
Astronomers have proposed the black hole seed theory to explain the formation of supermassive black holes in the universe.
This theory posits that supermassive black holes existed in the early universe during the Big Bang, initially as small seeds of black holes that would grow with the expansion of the universe. The black hole seeds near the core of the Big Bang would become supermassive black holes over a short period.
This is why the James Webb Telescope can detect supermassive black holes tens of millions of light-years away, and it also explains the formation of supermassive black holes at the center of the Milky Way and the center of galaxy M87.
In the long term, supermassive black holes in the universe will continue to consume nearby stars and increase in size. Therefore, some people worry that all matter in the universe will eventually be consumed by black holes, but this concern is unfounded, as the existing supermassive black holes no longer have any stars nearby.
Whether it is a star or a globular star cluster, they are all located outside the event horizon of the black hole and will only be affected by the black hole’s gravitational pull. Thus, they will not be consumed by the black hole.
A black hole is a dark region detected when orbiting a normal star. The properties of the normal star help astronomers infer the characteristics of the dark companion object, which is the black hole. The first confirmed black hole was Cygnus X-1, the brightest X-ray source in the constellation Cygnus. Since then, many other cosmic black holes have been discovered in systems where a normal star orbits a black hole. (Image: ZME)
At this moment, humanity can only solve a portion of the many mysteries surrounding black holes. If we can create a miniature black hole in the future or detect a stellar black hole at a closer distance, astronomers may be able to learn more about them and even find ways to use the properties of black holes to distort spacetime and discover methods for creating wormholes.
Once we master wormhole technology, human civilization could quickly travel to locations tens of millions of light-years away and become a truly cosmic civilization.
