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Today I bring to you a topic that is very close to my heart..
I go ‘Stephen Hawking mode’ when I hear about this topic, so please bear me if I am exaggerating some/all things in this one.. I’ll try my best to keep you guys entertained!
So here we go..
A black hole.
What is it? How do they form? Why do such voids even exist?
I shall try my best to enlighten you about such puzzling anomalies..
Who else could predict the unpredictable other than the great Albert Einstein back then, when technology was in its childhood days, developing itself for the greater future we currently are in..
He predicted black holes in 1916 and the term ‘black hole’ was coined in 1967 by John Wheeler, a theoretical physicist; in plain English, those who use mathematics to describe certain aspects of nature.
The first black hole was discovered in 1971.
When you reach the event horizon, all hope of escape is gone. For instance, imagine going up the Niagara falls with a row boat.
If you are still not sure about the gravity of this topic (pun intended, lol), I shall elaborate it for you..
By definition, a black hole is a region in space having a gravitational field so intense that no matter OR radiation can escape. Black holes are formed when giant stars die. And by giant I mean, at least 20 times the size of the sun.
A Dying star
As the nuclear energy within a star starts running out, gravity starts to overcome pressure, increasing core density and gravitational force.
Nuclear reaction stops and the star explodes as a supernova, expelling outer parts of the star into space.
By definition, a supernova is the explosion of a star.
And then the core collapses under its own weight into a single point of infinite density, singularity.
Gravitational forces at this stage are so strong, even light cannot escape from its pull. The image above is a moment captured from the movie “Interstellar”, one of my all time favorites. Now, putting aside the fantasy stuff, let’s get into the technicality of a black hole..
A black hole consists of three “layers” – the singularity, the outer and inner event horizons.
Event horizon is the boundary where when you reach, there is no coming back. Once a particle crosses the event horizon, it cannot leave. The black hole sucks all matter with it’s intense gravitational pull. An interesting thing about the event horizon is that gravity is constant across it.
The singularity is where the main part comes in picture.
In the center of a black hole is a gravitational singularity, a 1 dimensional point containing huge mass in an infinitesimally small space, where density and gravity becomes infinite and space time curves infinitely. This is where our laws of physics betray us, they cease to operate and everything seems incomprehensible.
What is space-time curvature?
The image below is a quick answer to the above question..
According to a hypothesis, a black hole’s singularity remains hidden behind its event horizon, in that it is always surrounded by an area which does not allow light to escape, and therefore cannot be directly observed. The only exception the hypothesis allows(known as a “naked” singularity) is the initial Big Bang itself!
Theoretically there are 3 types of black holes;
- Stellar black holes
They form where massive stars collapse. Masses ranging from 5 to several tens of solar masses (The solar mass (M☉) is a standard unit of mass in astronomy, equal to approximately 1.99 × 1030 kilograms. It is used to indicate the masses of other stars, as well as clusters, nebulae and galaxies. ~source: Wikipedia)
2. Supermassive black holes (Quasars)
These type of black holes can have a mass equivalent to billions of suns. They likely exist in the centers of most galaxies including our own, The Milky Way. We are unaware of how a supermassive black hole forms, but are predicted to be a by-product of a galaxy formation. They are also known as Quasars.
3. Miniature black holes
Though miniature type black holes are undiscovered until now, they are thought to have been formed shortly after the “Big Bang”. They are assumed to have much smaller mass than that of our Sun.
Another division separates black holes that spin (possess angular momentum) from those that don’t spin.
Einstein’s General Theory
The great German physicist Albert Einstein found another way to explain how space, light and matter would behave close to a black hole. In his General Theory of Relativity of 1915, Einstein proposed that the gravitational pull of an object such as a black hole would result into curving of space, in the same way that a person can curve a trampoline. A massive object creates a large dent in space into which light and matter would fall. The denser the object, the greater the dent. A black hole, being the densest of all, creates a dent so deep that nothing can escape from it. There’s so much to talk about Einstein’s General Theory of Relativity that I would like to dedicate a separate blog post for it alone.
Black holes are invisible, but it is possible to detect them by studying their effects. Astronomers observing a star called Cygnus X-1 saw that it was giving off enormous amounts of energy. They discovered that this huge, hot blue star was being dragged around in a circle by an unseen object, with a huge gravitational pull. That unseen object, astronomers now believe, is a black hole, which is tearing gas from the star. The gas forms a whirling disc before plummeting into a black hole. As it falls, it travels faster and faster until it moves almost at the speed of light itself. Close to the hole, the gas becomes so hot it emits massive amounts of energy.
That’s all for today guys. Thanks for reading.