Muskan, student of Saksham Sanchar Foundation wrote an informative article on black holes..
Black holes mainly formed when the centre of a very massive star collapses upon itself.
Centre of stars contain some material and due to which there are nuclear fission reactions that take place ,which produce heat and light but one day the fuel ends and the star will collapse.
There is a chart related to life cycles of stars.
It is a region where gravity is so strong that nothing , not even light and other electromagnetic waves are capable of possessing enough energy to escape it.
It acts like an ideal black body and grows by absorbing mass from its surroundings.
The first image of black hole was captured on 10th April 2019,which proved its existence.
One important feature of black hole is its Accretion Disk.
As gravitational force increases in black holes , the gaseous matter and objects attract towards it and start revolving.It emits Electromagnetic radiations.
This astonishing idea was first announced in 1784 by John Michell. He was also the first to apply the new mathematics of statics to astronomy.
The idea of black hole was rediscovered in 1916, after Einstein published his theory of gravity. Karl Schwarzschild then solved Einstein’s equation for the case of a blackhole which he envisioned as a spherical volume of warped space surrounding a concentrated mass and completely invisible to the outside world.
The term blackhole was coined by Princeton physicist John Wheeler in 1968.
Einstein’s theory of relativity:
It was basically divided into two parts
- A Special theory of relativity: published in 1905 , tells us how speed influences time. As we move faster , time slows down and it is called kinematic time dilation.
- General theory of relativity: Published in 1915 , it states that as gravitational force increases, time slows down.
So from it we conclude that gravity affects everything. At that time the concept of black holes was only theoretical.Later on this theory also states the centre of black hole as Singularity – A region where spacetime is infinite.
Photonsphere – A region where light can travel in circles and gravity is too strong. Everything beyond it is black.
Later on there were so many theories and discoveries which leads to discovery of black holes :
- By David Finkelstein : Published modern interpretation of black hole in 1958.
- Jocelyn Bell Burnell : Discovered neutron stars in 1967 , which leads to further research on black holes.
- Robert Oppenheimer and Hartland Snyder : Predict the existence of black holes in 1939.
- Subrahmanyan Chandrashekhar : Realised that these stars would have to collapse after they ran out of fuel.
There were also so many other theories related to black holes.
Astrophysical theory allows black holes to come in many sizes , size is simply directly proportional to its mass. Larger the black hole, lower its average density and it is conceivable that our entire observable universe is a supermassive black hole .
Types of black holes :
- Stellar black holes : most common type, formed due to stars and there are mainly 10 million to 1 billion stellar black holes in our Milky way galaxy.
- Primordial black holes : they are present theoretically only, but as scientists believe they are as small as atoms and their mass is as much as mountains.
- Supermassive black holes : their mass is more than equal to the mass of 1 million Suns. Every galaxy contains a supermassive black hole . In Milky way galaxy it is named Sagittarius-A*.
- Intermediate black holes : As scientists said that maybe there are black holes present between Stellar black holes and supermassive black holes.
The first object which was discovered and accepted as black hole was Cggnus X-1 in 1971 by Paul Murdin and Louise Webster.
The black hole conundrum: Science has scratched the surface, but the depths remain unexplored.It is also true because no one knows what is behind the event horizon. Space is also a mystery in itself .