INDIA: Blackhole is perhaps the most astonishing paradox in the known universe. There is a black hole present at the center of every galaxy in our universe. The stronger the force of gravity, the higher the escape velocity you need. Black holes are the most extreme example of this, where the escape velocity exceeds the speed of light. To get out of a black hole, the speed of person should be greater than the speed of light. Since, nothing can travel faster than light, it is impossible to escape from a black hole. There is so much mass squeezed into such a small volume that nothing can escape it.
Blackhole is named after a prison in Calcutta (modern day Kolkata) where prisoners went in but never came out.
The mystery of the black hole
The name “Blackhole” came in the late 1960s. Before that, it was called by different names such as dark stars, gravitationally collapsed objects. The main idea of black holes came after the famous papers of Albert Einstein published in 1915 (General theory of Relativity) where gravity is proposed as the curvature of the space-time fabric. The denser the object, the more it curves the fabric of Spacetime, the more the curvature is the stronger the gravity becomes.
In 1916, Schwarzchild found a solution to the field equation of Relativity, which predicted a special distance from a black hole known as Schwarzchild radius or event horizon, beyond which nothing can escape the pull of black hole. The center of the black hole is called a singularity when all of the mass of the black hole is squeezed into an infinitely small amount of region of infinite density creating an infinite curvature of space-time. Although it may not be true, we need a theory of quantum gravity to understand it.
Black holes are born when a star dies in a specific way. If a star with a mass greater than 1.4 times of the mass of the sun dies, (runs out of its fuel) it collapses into a white dwarf. Above this limit (Known as the Chandrashekhar’s limit) stars explode in a violent way known as ‘Supernova’ and collapse into an even more dense object known as neutron stars.
As the stars of mass 2.17 times more than the sun dies it results in an even denser object. A BLACK HOLE. But the explosion of stars is not the only way of creating black holes, there are giant black holes that are millions to billions of times the mass of the sun, they are known as supermassive black holes. Interestingly, their existence still remains a big question.
Speculative theories
Black holes were just a theory until April 19, 2019 where the first picture of the black hole was discovered. The black was named M87 which is a supermassive black hole located in M87 galaxy and is around 55 million light years away from us (1 light year is the amount of distance covered by light in a year). Although the image captured was not as sharp as expected but it confirmed what Einstein’s general theory of relativity predicted long ago.
There are many speculations and theories regarding black holes, such as the white hole which is just the opposite of a black hole where nothing goes into it but can come out of it. Another theory suggests that every black hole may be an opening towards a whole new universe and our whole universe might itself be a black hole.
But again these are all just highly speculated theories. But one thing is sure, that black holes are very fascinating objects, and studying about them can unfold many mysteries of the universe.
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