The Gazette Today


Black hole : A mystery simplified

4 min read
Black Hole

Science is the manifestation of man’s inquisitiveness and determination to finding answers to whatever intrigues him.
The most fascinating subject for him has always been the mysteries of cosmos and what can be more mysterious than a ‘Black hole’.

It took almost a century to shape the definition of this bizarre and humongous object in the depth space, that too without any evidence of its existence. From John Michell in 1784 to Albert Einstein in 1916 and Hawkins later, all gave their contribution to its concept.

Black hole is an astronomical object with gravitational pull, so strong that nothing, not even light can escape from it. It has remarkably high density and gravity.
It has a surface where the velocity needed to escape from its pull exceeds the speed of light which is practically impossible to attain, this boundary is called the event horizon.

Black holes vary in sizes and thus are divided into 4 categories :

1. Miniature : Can be as small as an atom but weighing almost equal to a mountain.
2. Stellar : as large as an asteroid but with a mass of around 10-100 suns.
3. Intermediate : as large as a planet with a mass of around 100 to 1 million suns.
4. Supermassive : as large as our solar system with a mass of millions to billions of suns.

Black holes are said to be formed when a massive object (usually a star with mass more than 20 solar masses) collapse (due to exhaustion of nuclear fuel at the core) and all its mass gets concentrated over a very small volume, thus providing it enormous density and gravity that it starts absorbing other stars and even merge with other black holes and finally turn to a supermassive black hole and every large galaxy has one at its center.
The one at the center of our milky way galaxy is called Sagittarius A.

There is a point at the center of a black hole which contains huge mass in an infinitely small space, thus density and gravity there, becomes infinite and laws of physics cease to operate. It is called gravitational singularity and is the most interesting topic for scientists.

Some Interesting facts :

  1. Einstein, in 1916, using his general theory of relativity gave strong reasons for the existence of such an entity and his theoretical estimates are found to be flawless in present day practical observations.
  2. The term ‘black hole’ was first coined in 1967 by astronomer John Wheeler, as the entity is invisible in the dark space and can only be detected by satellites and telescopes due to the presence of massive clouds of gas around it and radiation emitted by the remains of stars circulating it before falling into it.
  3. In 2019, astronomers, using the Event Horizon Telescope (EHT), an international collaboration that networked eight ground based telescopes into a single Earth-sized dish, captured an image of a supermassive black hole for the first time. The black hole is located at the center of a galaxy called M87, 55 million light years away.
  4. Another observation related to black holes came in 2015, when scientists first detected gravitational wave ripples in the fabric of space, whose existence was predicted a century ago by Albert Einstein’s general theory of relativity, was observed at the National Science Foundation’s Laser Interferometer Gravitational wave observatory (LIGO) detectors located in Washington.
  5. Meanwhile, the main telescopes around the world, engaged in studying black holes are : NASA’s Hubble, Chandra, Swift, NuSTAR and NICER.

This image reveals the black hole at the center of Messier 87, a massive galaxy in the nearby Virgo galaxy cluster. The black hole resides 55 million light-years from Earth and has a mass 6.5 billion times that of the sun. EVENT HORIZON TELESCOPE COLLABORATION ET AL.

Your curiosity would certainly be asking a question from you, what would happen if we try to cross the event horizon?
Well, scientists say that, if a person ever happens to do it then his body will be squeezed like a spaghetti (due to huge and uneven gravity), the phenomenon is called spagettification.

A more meaningful question here will be, why are they investing time on studying something that has practically nothing to do with our lives.
Well, the simple answer would be, to gain enlightenment of what, how and why everything is the way it is and study of black holes is supposed to unravel these mysteries of universe to a large extent.

Although these mysteries of nature have given a destination to a man’s curiosity but they can never channel it. The limits of curiosity extend far beyond the limits of the universe.
If your curiosity wants more of it, I recommend you to watch the movie ‘interstellar’.

Source of information : NASA’s official website

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