Science says that no photo of black hole can be taken, then what is this?

Using the Event Horizon Telescope, scientists obtained an image of the black hole at the center of galaxy M87, outlined by emission from hot gas swirling around it under the influence of strong gravity near its event horizon. Credits: Event Horizon Telescope collaboration et al.

On April 10, for the first time, a photo of a black hole was taken. Black Holes are considered to be one of the biggest secrets of space. Obviously this news had to be ridden in the world and so did it.

But actually this first real photo of a black hole is not a direct image of the supermassive black hole itself, which is situated at the heart of M87 galaxy. This is due to the fact that any light beam, even the X-ray or gamma ray, can never come back after entering a black hole? So, how this image was photographed? It is compulsory for any photo that either the object is transmitting light/radiation, or the light/radiation of another source is coming back after it collides.

Black holes swallow any kind of light, matter or radiation that comes near them. So, it is absolutely impossible to take a direct photo of it. The colorful photo of the supermassive Black Hole of the Galaxy named Messier-87, located in Virgo constellation, is a computer-composed, virtual photo like an imaginary picture made by the hand of an artist. . This black hole is 55 million light years away from the Earth, more than 6.5 billion times more massive than our Sun and expands upto the size of our entire solar system. It is like an imaginary big dark moon that stretches 100 billion kilometers across!

How a virtual picture of a black hole is taken?

The data associated with the event horizon near the black hole is used to create this virtual picture. In this image, these figures were assembled by combining eight powerful telescopes all over the world. This technique, called 'Very Long Baseline Interferometry' (VLBI), became an integrated virtual telescope called 'Event Horizon Telescope' (ELT), which acted as an earth sized telescope by combining the size and capacity of all those telescopes. It resulted in an image that was one million times better than the space-based Hubble telescope.

Zooming in on the heart of the Milky Way (The Supermassive black hole Sagitarrius A*). Credit: ESO/GRAVITY Collaboration

In the ongoing experiment since April 2017, the American Space Agency 'NASA' has also made significant contribution to the Chandraya X-ray Observatory, an observatory in space since 1999. As the name suggests, this Space Observatory has been named after Subramanian Chandra Shekharhim, an Indian astronomer. He was awarded the Nobel Prize in Physics in 1983. He was the nephew of physicist CV Raman, the first Nobel Prize Physicist in India and the only Nobel Prize awarded to India.

Event Horizon:

Event horizon of a black hole is said to be that boundary between spacetime and the black hole from which anything such as stars, constellations, nebulae (gas clouds) or light rays themselves can never return once they enter it. This is the place where all such things are sucked in by the black hole's unimaginable gravitational pull and they fall into it. The picture published on 10th April is this 'event horizon', in which the orange plasma shows the illumination of the gases, and not the original black hole.

According to astronomers, whenever any object wanders near a majestic black hole, then it gets flattened like a giant saucer by its gravitational pull. This object is shredded into pieces and is fragmented into its constituent molecules and atoms, like the whirlpools formed in the water falling into a pit. It starts rotating the black hole at constant speed. At the same time, it continues to stretch towards the black hole in the shape of a flask.

Almost light speed

Ultimately, all the matter becomes almost as fast as the speed of light. There is enormous amount of friction between the molecules and atoms of this matter. So, they turn into plasma, and produce X-rays and gamma rays, crossing the 'event horizon' with a hallosphere-like glow. The photo that has been published is a circle of similar brightness at some distance from the black hole. The dark part of the middle should essentially be the black hole. This photo has not been created instantaneously or just in a day, but with the help of computers, it has been created in months.

Finland's astronomer Tuomas Savolinenen says that black holes are so powerful that their magnetic arms can reach upto 300 light-years away. Although they are millions or even billion times massive than our Sun, they are often smaller in size, as this mass is squeezed into a very tiny region. Every black hole is actually a corpse of a dead star with very high density. Living stars shine with the energy produced by the fusion of hydrogen atoms in their core. They can remain luminous for a very long period of time, as long as there is a balance between two types of forces. One is the gravitational force created by their own mass, which tries to pull the star inside. The second one is the radiation coming out of their center, which tries to push the star to expand outwards. But when the star runs out of its hydrogen fuel, it starts shrinking due to its enormous gravity.

Our sun will become a white dwarf

Stars like our Sun, after death, turn into white dwarves or white dwarf stars. They gradually become cold and disappear from the visible sky. A much larger star with many times more mass than the Sun, end up with a huge explosion, which is known as the supernova. In this process, a lot of substance from the stars spreads in all the directions in the space. However, a small solid body remains in the center of the fragmented star. This is called a neutron star.

This neutron star is so dense that the weight of its just one teaspoonful is equal to several billion tons. Even after the supernova explosion, the gravitational contraction of this remaining  core continues further. Eventually, it becomes so dense and its gravitational pull is so enormous that even light can't come out once it enters this region. This stage of a star is called black hole.

A Black Hole is Unimaginably dense:

Any black hole is unimaginably dense. It can be imagined from this example that if our earth were to become a black hole, then its entire mass would be concentrated in a region not larger than a tomato! Studies have shown that there is a supermassive black hole at the center of almost every galaxy in this universe, including our Milky way galaxy.

Our solar system is located 26,000 light years away from the center of Milky Way which consists of a supermassive black hole named Sagitarrius A* or Sag A*, which is 4.3 million times massive than our sun. With the help of 'EHT' telescopic, a second image of this black hole was also taken, but its image was not as clear as the other one, due to the presence of a huge amount of stars, dust and gas clouds which prevents the light to reach the EHT telescopes, that is coming from the event horizon of Sag A*.

Press conference in six cities

The computer picture on April 10 was presented at the press conferences held in six cities of the world. These six cities also had a Belgian capital Brussels. Hino Falke, professor of astrophysics at the University of 'Elt' Science Council and Rudbud University in the Netherlands, told reporters that the picture also shows the shadow of the black hole in the background of a bright circle of 'event horizon'. With the help of this shadow, it was determined, how big is the black hole of the black hole 'M 87'. Paul T. P. Ho, a member of the President of the East Asia Observatory, said at the same press conference, "Many of the attributes that are shown in this picture match with our theoretical understanding."

It was told at a press conference in Brussels that this dark shadow of the black hole observed through a radio telescope, located fifty-five million light years away from the Earth, is also a surprise. It was possible due to a cosmic coincidence: Earth's atmosphere is coincidentally suitable for microwave radio waves that come from the 'event horizons' of a black hole. However, in our galaxy, the microwave radio waves coming from the Black Hole called 'Sagittarius A', which is 26,500 light-years away, are so weak that scientists are not able to gather as much information like 'M87'.

Science also needs advertising

The computer-composed picture of the 'M87' black hole is not an actual image, but still it is a major scientific success in a way. Partial scientific breakthroughs also represent a success today, so that they stay in the discussion and get money for their research projects. Especially the space related research projects are very expensive. But, sadly the public and the governments do not understand any practical use of them. That's why governments hesitate to invest big chunk of money available. Therefore, the scientists who are skilled in propagating their work by the media, are equally successful in getting the government wallet open. This marketing has also worked as a propaganda of 'M87' black hole's alleged 'first photo'.