Have you wondered how a black hole started its life? What would possibly happen if you were to cross the Event Horizon? As its name suggests nothing escapes its gravitational pull so much so not even light can escape!
A supermassive black hole releases as much energy as a galaxy! The fabric of space is bent so far into space time that, time dilation near a black hole is massive. However near singularity (where all the mass is concentrated of the black hole and has infinite density) time is immeasurable from an observer on Earth. A second spent there would be an eternity. However before we dream about reaching singularity we have to wonder is it even possible. Frankly, it’s not possible chances are you will be dead due to the tidal gravity and believe me we can certainly say the experience won’t be as pleasant as it was in the movie Interstellar. However what happens after the Event Horizon is a mystery but there are certain theories. A black hole started its life as a massive Star at least 10-20 times the mass of our Sun to form a black hole. Otherwise the mass of the star would not be sufficient enough to make the star collapse into itself (which forms a singularity) due to immense gravity. We will look deeper into how a black hole forms, some of its features and predict what happens near and after the realm of no escape in this blog and the next blog.
A star which would have formed typically in a cluster would have to be 3 times the mass of our sun at least to form a neutron star or even have a shot at forming an intermediate black hole.
Towards the end of its life the star starts to shed some of its layers, as I explained in my solar system blog. This is when all the elements up until Iron has been synthesized by Nuclear Fusion of smaller successive elements. It is similar to carbon formation by nuclear fusion of lower atomic mass elements like hydrogen and helium. The same process continues till element 56(Iron), after this point carrying out nuclear fusion is pointless (this part pertains to a stars life as I wrote in my previous blog). After fusion of Iron, more energy is supplied to carry out fusion than energy received by nuclear fusion which is inefficient and the star cannot supply more energy as it is out of fuel. Thus as no nuclear fusion occurs the star starts to die. Eventually in a final bang known as a supernovae the star sheds all its layers and returns most of the substances back into Interstellar Medium.
Some other elements larger than atomic number 56 forms at this point due to high temperatures and pressure, this is partly why we find elements larger than Iron in atomic number. Large stars living few millions of years was common back in the day as clusters would be different in early days than they are now. The only thing remaining after the supernovae is the stellar core of the star. As I mentioned before that in order to have a star, dynamic equilibrium is to be maintained, nuclear fusion helps to do this by counteracting gravity pulling it inwards. As nuclear fusion has stopped and this stellar core has lots of mass in a small volume which disrupts the hydrostatic equillibrium, the core collapses altogether into an infinitesimally small space where all its mass is concentrated.
According to General theory of Relativity this means that space time is bent inwards massively due to such a dense point mass.
This creates a black hole in simple words. Thus we can see a trend, more massive the star the higher chances of a bigger stellar core collapse and a black hole forming. However at times it can form a neutron star where atoms break due to immense gravity and neutrons swim in the star. That is how a stellar black hole is born and it’s the most common one. There are supermassive black holes in the center of many galaxies like ours. There are intermediate black holes but have not been discovered yet. Miniature black holes (commonly known as primordial black holes) are debatable till this day as they have not been spotted as it is truly hard to spot black holes, especially ones which have a diameter of an atom. We should know that black holes are not vacuum cleaners as depicted everywhere. Most planets could orbit a stellar black hole with a mass of their original star. Swarzchild radius
is the radius of the event horizon, it also helps to determine the minimum radius of a certain mass to cause irreversible collapse.
Even a black hole dies if not fed but normally supermassive black holes live forever due to constant food supply by collisions of the host galaxy with other galaxies. The food is presented to the center of the galaxy due to the tidal forces of the galaxy which allows supermassive black holes to grow even larger. Eventually the accretion disk runs out of food and the quasar stops glowing. Stephen Hawking discovered the Hawking Radiation where virtual particles ( it is believed antiparticles and particles form out of nothing and annihilate each other which was not the case years back when people thought the vacuum has nothing) constantly annihilate each other by forming in vacuum and destroying each other.
These antiparticles and particles may pop up near a black hole and might not annihilate each other as the gravitational pull of the black hole might prevent any war between the particles. Overtime these absorbed antiparticles may keep annihilating mass inside the black hole causing a case of weight loss (I wish it was so easy to lose weight). The left over particle which could not annihilate its partner particle is ejected which can be detected as the Hawking Radiation. Overtime the black hole might become too thin and unstable, eventually ejecting all its mass as abrupt eruptions leading to death. That is a way a black hole could die but chances of it happening are low.
It is believed that flashes of light or bright light near singularity can be seen as the swallowed stars produce light which could not escape. However reality is far from seeing flashes of light. I explain few more speculative possibilities in my more detailed blog on black holes itself.
More of the features of a black hole will be discussed in a future blog in order to not make this one spaghettfied like a black hole’s effect on an object too close to the event horizon. This blog was to give an insight into the birth, life and death of a stellar black hole. I have explained the other types of black holes in the other blog. Learn more about black hole features in our next blog.
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