There are countless kinds of celestial bodies in the vast universe, including common stars, planets, and some very special and powerful celestial bodies, such as neutron stars, pulsars, black holes, etc. Among the numerous celestial bodies, the most mysterious, powerful and terrible one should be the black hole, which is a kind of celestial body existing in the space of the universe in modern general relativity. The gravity of the black hole is so strong that the escape speed in the event horizon is faster than the speed of light. Therefore, “a black hole is a celestial body whose curvature of space-time is so large that light cannot escape from its event horizon.”.
It is because the gravity of the black hole is so strong that it is unimaginable that once any celestial body and matter close to the black hole, they can’t escape and will be swallowed by it, even light. Because of its powerful phagocytic ability, black holes cannot be observed directly.
Since black holes cannot be observed directly, how can we find them? The strong gravity of black holes is one of its strengths, but also one of its weaknesses. It is just by taking advantage of this weakness that scientists can discover the existence of some black holes. Because black holes can constantly devour all kinds of celestial bodies and materials, a very obvious accretion disk will form around them.
The black hole itself does not emit light, but this accretion disk can emit very bright light. Therefore, we can find the existence of black holes through the accretion disk, but the mass of such black holes is very huge, and only supermassive black holes can form a very obvious accretion disk, which can be observed by us. For example, the supermassive black hole in the center of the Milky Way galaxy, 55 million light-years away from the earth, is the black hole in the first picture of human black hole.
However, the number of supermassive black holes in the universe is relatively small, so we can observe very few black holes. Black holes are not only supermassive black holes, but also medium and small black holes with medium mass or even low mass. They are the mainstream of the black hole family. Scientists speculate that there may be at least millions of black holes in the galaxy, all of which are of medium and small mass.
However, it is difficult to find the existence of such black holes because there is no obvious accretion disk or no accretion disk at all. If we want to find small and medium-sized black holes, we need more powerful observation equipment. Observing the X-rays in the universe is the main way for scientists to find black holes, because black hole accretion disks emit bright, easy to find X-rays.
Even medium-sized black holes can emit weak X-rays as long as there is an accretion disk. By exploring such weak X-rays, we may find some hidden small and medium-sized black holes. The scientists studied a binary system consisting of a giant 2 mass j05215658 + 4359220 and a companion. In a unique way, they found that it might be a low mass black hole.
Scientists have combined Doppler stellar data with data from the asas-sn project. Through these data, scientists can see the brightness of stars changing with time. If there is a small mass black hole in a star system, the brightness of stars may show some very regular brightness changes under the influence of black holes.
By combining these two factors, scientists have discovered a hidden black hole in a stellar system. The brightness of a star is constantly changing, and it turns out that the brightness change is consistent with the orbital period of the object around the star. And this object is a small black hole about 3.3 times the mass of the sun.
In fact, the above method of looking for medium and small mass black holes still uses the accretion disk effect of black holes. In a stellar system, we can look for some medium and small mass black holes by observing the brightness changes of stars. But if some black holes are not in the stellar system, or it is very far away from the main star, it may not cause obvious brightness changes of the star.
In particular, black holes in interstellar space may not be surrounded by matter or celestial bodies for it to swallow. At this time, such black holes may not have accretion disks at all. We are basically unable to find, and this kind of black hole that cannot be found by us accounts for more than 90% of the black holes in the universe. In other words, most of the small and medium-sized black holes can’t be found by the existing observation technology.
Some people may think that exploring and searching for black holes has little to do with human beings. We just need to observe and study supermassive black holes. For those small and medium-sized black holes, since they can not be found, there is no need to care about them. But is it really that simple? Scientists research and explore the technology of small and medium-sized black holes, not only to explore the mystery of black holes, but also for the future of mankind.
As we all know, with the rapid development of human science and technology, in the future, we must go to the starry sky, go out of the solar system, and go to various galaxies for exploration. Even when we become an interstellar civilization, it’s possible to explore the entire galaxy, the entire universe. When we travel in the universe, we may have to face many unknown disasters.
Some disasters can be predicted and avoided in advance. For example, if a supernova explosion occurs in a galaxy, we can observe it in advance, and then the interstellar route will avoid this area. For another example, if a celestial body collides with our spaceship, we can also find and avoid it in advance. Even if we have to encounter an alien civilization, we can also observe and find it in advance.
But there is only one kind of celestial body, which we may not be able to observe at all, thus bringing devastating disaster to our spaceship. This kind of celestial body is black hole. If there are many black holes in the universe, and most of them are medium and small mass black holes, then these black holes are space-time traps. Once we fly into it, we can imagine that there is no way out.
Therefore, in the future interstellar navigation, black holes may be the most terrible threat we will encounter in interstellar travel. If we don’t have advanced detection technology, we can find the small and medium-sized black holes in front of us in time, then it’s too late to find them when our spacecraft enters the range of the black hole’s accretion disk. At that time, the strong gravity of the black hole will pull the spacecraft in and devour them.
Only when we have advanced black hole detection technology, we can find hidden small and medium black holes in the universe. We can mark them in advance and stay away from them during the interstellar voyage. Therefore, we can imagine that in the future, when human beings realize interstellar navigation, there will inevitably be interstellar navigation map. On this map, not only the positions of galaxies and celestial bodies will be marked, but more importantly, the positions of hidden black holes will be marked, and they will be circled by key points.
Of course, the black hole is a very powerful and terrible celestial body in human cognition, but with the continuous progress of human science and technology, when we really understand the nature of the black hole. Maybe the black hole is not so terrible. Maybe in the future, in order to explore the internal mystery of the black hole, we will take the initiative to enter the black hole. Of course, to enter the black hole exploration, we must have the ability to get out of the black hole safely.
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