China News Network Client Beijing, April 9th ​​(Reporter Shangguan Yun) In 2019, a photo of a black hole shaped like a donut was announced, which aroused public attention. A few days ago, another picture simulating "black hole engulfing the sun" was screened online: a star was torn by a black hole with tens of thousands of times the mass of the sun, and the scene was magnificent.

This triggered the imagination of many astronomy fans and science fiction enthusiasts: Is there really a "wormhole" in the black hole? Is it possible for mankind to reach the black hole by spacecraft for exploration?

In response to the above problems, Gou Lijun, a researcher at the National Astronomical Observatories of the Chinese Academy of Sciences and the chief scientist of the stellar star black hole research group, said in an interview with a reporter from China News that black holes devour stars. As far as the current technical level is concerned, exploring a black hole by a spaceship is only a beautiful ideal, and it is not reliable.

Data map: On April 2, local time, the image provided by NASA shows a simulated scene of a star torn by a black hole with tens of thousands of solar masses. The picture is magnificent and magnificent.

Black holes devour stars? very common

In the universe, the phenomenon of black holes swallowing stars is actually very common.

"For example, in the Milky Way, nearly half of the stars are in a binary system, that is, there are two stars in this system." Gou Lijun explained that the two stars may have different masses, and the greater the mass, the faster the evolution.

Over time, the star with a larger mass is likely to evolve first to form a black hole. At this time, it will tear the gas on another star and eventually "swallow" it, which can be regarded as a natural celestial phenomenon in the universe.

"The solar system is only a stellar system, and the Milky Way is considered a galaxy." Gou Lijun said that the Milky Way contains almost 200 billion to 400 billion stars, and the sun is only one of them. "Fortunately, at present There are no such terrible black holes near the solar system, otherwise the entire solar system will be in disorder, and the earth will no longer exist. "

Subtle differences and classification

Although they are all called black holes, there are nuances and categories.

"Generally speaking, in terms of mass, one type is a star-shaped black hole, which is generally three to one hundred times the mass of the sun; the other is a medium-mass black hole, whose mass is between one hundred and one million times the mass of the sun. Between; there is also a type of supermassive black hole, the mass is particularly large, can reach billions or even tens of billions of solar mass. "Gou Lijun introduced.

In addition, there is a special kind of black hole called "primary black hole". It is not formed by the evolution of stars, but is produced by the direct compression of cosmic matter after the Big Bang. The mass may be very large or it may be very small.

Data map: Previously, scientists discovered a super-large black hole with a mass of 40 billion times the sun in the Holm 15A galaxy cluster 700 million light years away from Earth. If confirmed, it would be the largest supermassive black hole in this area with a radius of about 1 billion light years.

"After Pluto was relegated to a dwarf planet, people are still persistently searching for the ninth planet of the solar system. At this time, it was proposed that the ninth planet of the solar system is actually an original black hole, and the mass of it is about three or four times the earth. Quality. "Gou Lijun described that if it is an earth-quality black hole, its diameter is less than two centimeters.

How to understand the name "black hole"?

Since black holes are not "holes", why did they choose this name?

"The black hole has a characteristic: after falling into anything, it will never escape again, just like the" bottomless hole "often mentioned in our lives." Gou Lijun said, it is conceivable to fall into the edge of a big waterfall, and never again May come out of this edge. Of course, when it comes to black holes, falling in all directions is the same result.

In addition, the black hole itself does not emit light. It seems that the center is always a black lacquer. Combined, people finally gave it the name of "black hole", which is just an image metaphor.

In April 2019, the first black hole photo in the history of mankind came out, which caused worldwide attention. However, it looks a bit like a "doughnut".

Data Map: In 2019, a major astronomical achievement of more than 200 scientists around the world-the first black hole photo of mankind, was released simultaneously in many places around the world on the evening of April 10th, Beijing time. The Event Horizon Telescope (EHT) announced that it has successfully obtained the first direct visual evidence of a super-large black hole whose image reveals the black hole in the center of the supermassive galaxy M87 in the Virgo cluster, which is 55 million light-years away from the Earth and the mass of the Sun 6.5 billion times. Photo courtesy of the Event Horizon Telescope Cooperation Organization

"In layman's terms, the bright circle seen in that photo is actually the 'accretion disk' around the black hole. Without it, we can't see the black hole at all." Gou Lijun said that some people might say that the photo follows The black holes shown in some science fiction movies are not the same, which is actually related to the direction of the observed line of sight.

"For example, the black hole shown in" Interstellar Crossing "is viewed along the direction of the equator; and the photo of the black hole shaped like a donut is viewed along the direction of the two polar axes." Gou Lijun said.

Is it reliable to explore by spaceship?

Mysterious black holes have always attracted people to explore. Someone once opened their brains and came up with an idea: Can they ride a spaceship to explore its mysteries?

However, the ideal is full, the reality is very skinny. Generally speaking, the greater the mass of the black hole, the smaller the tidal force. A black hole with a smaller mass has a very high tidal force. When a person approaches, it may be pulled thin and long like noodles in an instant. The black hole in "Interstellar Crossing" has a super-massive mass and extremely low tidal force. People will not be pulled by force, and it is indeed possible to go alive.

"There is a saying that there may be a wormhole in the center of the black hole, and some passages lead to distant places." However, Gou Lijun believes that this is still a theoretical guess. As far as the current technical level is concerned, it is impossible for people to reach a black hole by spaceship.

The first problem is distance. The black hole is too far away from humans. He mentioned that the closest star-level black hole to the solar system is more than 3,400 light-years away. With the existing technology, it is impossible to build a spaceship to run at a speed close to the speed of light for more than three thousand years.

"For black holes, we currently use astronomical telescopes for observations, and gravitational wave detectors. There are many ways." Gou Lijun joked that although there is no hope of going to the black hole by spacecraft right now, maybe you can use a suborbital spacecraft to experience weightlessness in your lifetime. It feels good. (Finish)