The black hole, which has been only proven by theory, has finally been unveiled. The observation of black hole has become possible by using a network of major radio telescopes around the world as a single telescope of the size of the earth. This is the first time that the actual form of black hole has been observed since Albert Einstein, who figured out the relationship between gravity and time and space, presented the theory of relativity 104 years ago.
The results of the observations were shown by an international research team of the Event Horizon Telescope (EHT) project in the afternoon on April 10. "We succeeded in observing the first mass black hole (M87)," the researchers said. EHT, which includes 13 research institutes from major countries, including Korea, United States, Europe and Japan, connected the radio telescopes of eight space stations around the world. As a result, it had the same effect as a very large radio telescope with a total diameter of 10,000 km and allowed researchers to obtain a cosmic image that can only be obtained by a telescope with a resolution 1,000 times higher than that of U.S. Hubble telescope, the highest performance telescope in the world.
EHT initially targeted two black holes for observation. One was the Sagittarius A* black hole on the edge of Sagittarius of our Milky Way and the other was super large black hole M87 in the Virgo of another galaxy. The Sagittarius A* was an easier target because it was only about 26,000 light years away, but its images were not shown on April 10. In comparison, M87 is 55 million light years away from Earth, but it is so large in size that EHT researchers succeeded in observation. M87’s mass is 6.5 billion times that of the sun.
Precisely speaking, the photographs and data shown by EHT are event horizon, which is the boundary of a black hole, rather than a black hole itself. The EHT researchers called it the “shadow of a black hole.” The black hole itself has such high gravity that it swallows light, and it cannot be observed with any conventional optical or electromagnetic telescope. Instead, just before entering the black hole, the object emits the energy particles at the end of the boundary, which can be observed by the radio telescope. Sometimes, the light shining from the bright sky behind the black hole acts as a halo along the event horizon, presenting the shadow of the black hole. As a result, the center of the black hole is dark, and brightly flashing image with ejected energy or halo effect on the outside of the boundary is observed with telescope.
Dr. Son Bong-won of the Korea Astronomy and Space Science Institute, who participated in the EHT project, said this achievement is “the ultimate proof of the theory of relativity.” Dr. Jung Tae-hyun of the same institute added, "With this finding, we can now prove the research results of Arthur Eddington and Steven Hawking, who laid the foundation for the theory of gravitational fields, including black holes, after Einstein."
It is difficult to estimate how the identification of black holes affects our lives as well as science. Some people think it will be possible to use a spacecraft (warp navigation) like in a science fiction movie in the far future, and others, more practically, think that an accumulation of know-hows of spectroscopy, which observes and analyzes physical conundrums such as black hole, electromagnetic engineering and physics will be useful for communication and electromagnetic. Jung said, "Wi-Fi, which we use in our daily lives, is derived from scientific research and technology exploration for astronomical observations. Astrophysics is basic science, but the influence of its technological power is infinite."
Six articles on the results of the black hole were published in a special edition of the U.S. astrophysical journal Letters. Eight researchers from the Korea Astronomy and Space Science Institute participated in the research project. In addition, the Korea VLBI Network (KVN) contributed to observation and analysis.