Why did the original title Donuts get blurred? Scientists say that ____________
Speech 118 of Shanghai Science Popularization Forum Seeing Black Hole was held at Shanghai Science and Technology Museum on 14th. Shen Zhiqiang, director of the Shanghai Observatory of the Chinese Academy of Sciences, and Zuo Wenwen, associate researcher, shared with the public the story behind the first black hole photograph of human beings, which appeared a few days ago.
Searching for Black Hole Models
Human beings have never been able toseeblack holes so close as they are now, said Shen Zhiqiang, director of the Shanghai Observatory of the Chinese Academy of Sciences. He said that this is the significance of the first photograph of a black hole.
More than 200 scientists around the world collaborated to complete the first photograph of a human black hole, which was released on the evening of April 10, Beijing Time. The black hole image revealed a black hole at the center of M87, a supermassive Galaxy in the Virgo Cluster, 55 million light-years away from Earth and 6.5 billion times the mass of the sun.
Scientists first choose black hole models. Shen Zhiqiang said that scientists have been looking for black hole models for a long time, not only M87, but also supermassive black holes near the center of the Milky Way Galaxy (26,000 light-years away from Earth, more than 4 million times the mass of the sun).
According to reports, to photograph black holes, we need to choose very large black holes, and they are close enough. Therefore, supermassive black holes and M87 in the center of the Milky Way Galaxy are worthy candidate models. They look like the sun and the moon in the sky. They are similar in size.
Multinational cooperation to set up virtual telescope
Choose model and camera. Zuo Wenwen, an associate researcher at the Shanghai Observatory of the Chinese Academy of Sciences, told the audience that in order to take pictures of black holes, radio telescopes of the same caliber as the Earth are needed. At present, millimeter-wave radio telescopes are very difficult to achieve tens of meters.
Fortunately, she said, VLBI (Very Long Baseline Interferometry) technology can combine millimeter-wave radio telescopes around the globe to form a virtual telescope whose aperture depends on the distance between the two farthest telescopes. It was with this Earth-sized virtual telescope that the first black hole photograph was taken.
Scientists also said that in order to photograph black holes, telescopes from all over the world need to work together at the same time, which requires good weather at eight stations in six locations around the world, so it is a lucky thing to photograph black holes.
Why did the doughnut get blurred? Difficulty is like looking at an orange from the earth
Zuo Wenwenwen said that although the black hole photo did not achieve the ultra-high definition effect, it was not easy. Like you use your mobile phone to take a person in the distance, if you keep enlarging, the picture will be blurred. This picture has reached the level of an orange on the moon from the Earth. This is our best black hole photograph at present, and we will move towards higher resolution in the future.
Some netizens described the released black hole photo as a red doughnut. Zuo Wenwenwen explained that the color of light is not important, but it can also be used in green and blue. The photos mainly reflect the intensity of light in different positions. At the same time, she explained that we see the light outside the black hole, and the unknown black hole horizon is still in the center of the doughnut.
Will black holes grow larger and larger?
On that days popular science forum, there were many small audiences. As for black holes, their brains are wide open and they throw fancy questions.
For example, a small audience asked: Will black holes grow bigger and bigger? Zuo Wenwen answered that, on the one hand, black holes will eat themselves, on the other hand, when galaxies collide, two black holes in the middle of galaxies will collide, forming a larger black hole.
Another small audience asked: life has a beginning and an end, then will the black hole disappear? Zuo Wenwen answered that according to Hawking radiation, the mass of black holes can be slowly lost, but even very small black holes, such as a solar mass black hole, need a long time to disappear, so normal black holes are difficult to perish.