When we look up every day, behind the starry sky we can see, there is hidden a "monster" that has only been imagined for a long time, that is, a black hole. In 2019, a documentary from the UK recorded the complete process of humans "seeing" it for the first time. This was not only a scientific victory, but also a miracle created by global cooperation.
From theory to reality
The general theory of relativity, proposed by Einstein in 1915, predicts the existence of black holes. For the next century, it remained in mathematical formulas and theoretical deductions. Specifically, through many indirect evidences, such as the movement of stars around invisible celestial bodies and the X-rays emitted when black holes swallow matter, scientists have confirmed the existence of black holes. However, they have always lacked an intuitive "photo".
Direct observation of black holes will encounter great obstacles. For example, "Sagittarius A " in the center of the Milky Way, although its mass is very large, its opening angle in the sky due to its horizon range is extremely small, which is like observing a donut on the moon from the position of the earth. In addition, the black hole itself does not emit light, and is surrounded by turbulent accretion disks and interstellar dust, which makes related observations even more difficult.
Global telescope network
To overcome these problems, scientists came up with a bold idea: build a virtual telescope as big as the Earth. This is the Event Horizon Telescope project, or EHT for short. It is not a single device, but multiple radio telescopes around the world that are accurately synchronized using atomic clocks to form an observation network.
At the beginning of April 2017, these eight telescopes – the telescope in the United States, the telescope in Mexico, the telescope in Chile, the telescope in Spain, and the telescope in the Antarctic – were pointed at "Sagittarius A" and the central black hole of the M87 galaxy. They continued observations for several days and collected an enormous amount of raw data. The data is placed on hard drives weighing half a ton and transported by plane to data centers in the United States and Germany for processing.
Data processing challenges
The telescope collected not direct images, but radio wave data from the universe. Due to the limited number of telescopes, only "partial" information can be collected, which is like fitting together only a few pieces of a huge puzzle. The use of complex algorithms involves scientists filling in the missing data to restore the true appearance of the black hole.
Several teams from around the world worked independently on this work to avoid bias caused by a single algorithm. It took nearly two years and hundreds of researchers were involved in work related to this topic. They had to standardize the data to make it meet the calibration requirements, conduct detailed checks, and conduct in-depth analysis. Until April 10, 2019, the first black hole photo in human history was announced to the world.
That shocking image
The published photos show the black hole at the center of the M87 galaxy, which is 55 million light-years away from Earth. The image shows a bright ring with a deep dark shadow at its center. This bright ring is formed by the ultra-high temperature gas around the black hole that emits light under the influence of gravity, and the dark shadow in the center is the black hole itself, which is about two and a half times the size of the event horizon.
This image is highly consistent with the predictions made by Einstein's theory, once again confirming the correctness of general relativity under extreme gravitational conditions. It not only satisfies the long-standing curiosity of mankind, but also provides unprecedented direct observational evidence for studying the physical properties of black holes and verifying the theory of gravity.
Collaborative scientific spirit
The EHT project is a success and it can be regarded as a model of international scientific cooperation. It brings together more than 60 research institutions around the world, with more than 200 scientists participating. It crosses geographical boundaries, crosses cultural boundaries, and crosses political boundaries. The tens of millions of dollars in funding required for the project also come from the joint support of multiple science foundations around the world.
Facing common scientific frontier issues for mankind, this collaboration model proves that open sharing and sincere cooperation are the keys to achieving breakthroughs. From data collection to analysis and interpretation, every step contains the world's top wisdom, which embodies the true meaning of science without borders.
Exploration never ends
The first black hole photo is just the beginning. The EHT team is planning to expand the telescope array and add more stations to improve the resolution. The goal is to capture the dynamic changes of the black hole, and even try to create a video of the smaller "Sagittarius A*" black hole. These efforts will help us gain a deeper understanding of gravity, space and time, and even the beginning of the universe.
Every time we gaze into the depths of the universe, we are expanding the boundaries of human knowledge. This photo may seem blurry, but it is a real step towards understanding the ultimate mysteries of the universe, and it indicates that there will be more exciting discoveries in the future.
Will your view of the universe and humankind's scientific exploration capabilities change because of this photo of a black hole? This black hole photo was "taken" through the joint efforts of scientists from all over the world. You are sincerely welcome to share your insights in the comment area. If you think this article is valuable, please like it to support it and share it with more friends.
