When the black hole was first defined? A black hole is a region of spacetime where gravity is so strong

▲ The curvature of spacetime by black hole and others

that nothing, even electromagnetic radiation like light, can escape from it. It was predicted that black holes would exist when Albert Einstein released his theory, the Theory of General Relativity. It proved that the rule of Newton had had a problem and refined it. With the theory, Einstein believed that whatever has mass or has accelerated is related to the curvature of spacetime, and light moves along by the curvature. In this way, the existence of black holes was first implied.

The theory of General Relativity was proved by Arthur Eddington. The aim of his experiment was the observation of the gravitational lensing effect, which means the gravitational deflection. After then, in 1964, three scientists including Roger Penrose, Andrea Ghez, and Reinhard Genzel found a black hole at the center of our galaxy.

As everything including light cannot escape from black holes, it is hard to take a picture of a black hole. However, EHT (Event Horizon Telescope) researchers eventually made it on April 18th, 2019. They made it

▲ The first image of black hole

with the Event Horizon Telescope, which eight telescopes connect. In South Korea, eight researchers including KASI (Korea Astronomy and Space Science Institute) researchers participated in EHT collaboration as members of JCMT and ALMA project affiliated EAO. The image captured the Supermassive Black Hole (SMBH) at the center of M87 also known as Virgo A. When the light travels along by the black hole outside, it makes the shadow of the black hole. EHT made it taking a picture of the black hole, so thank you for the shadow of it.

A new image of M87's supermassive black hole was released on March 24, 2021. The image is embodying the magnetic field from SMBH. Light transfers energy as a transverse wave. Therefore, it is possible to polarize light by using specific filters. As light is a kind of electromagnetic relation, magnetic around light can serve the same role as the specific filters. Using this effect, EHT researchers could make a map of the magnetic field from SMBH.

May 29th, 2021. By Jiho Kim