One among the celestial entity, which is widely heard, Blackholes. What are Blackholes? How was it discovered? What led someone to throw a hunch like something like this exists? Do they exist? On the other hand, are they just a myth?
The idea of a body so massive that even light could not escape was briefly proposed by astronomical pioneer and English clergyman John Michell. Einstein proposed his theory of general relativity in the year 1915. Soon after the Einstein equations were publicized physicists started trying to find solutions to simplified versions of the equations. He found one that had the possibility that for a star small enough and heavy enough there was a distance such anything getting within that distance could never get out. In effect, Schwarzschild had discovered the possible existence of what later came to be known as a black hole. Soon, physicists like Roger Penrose, Vladimir Belinski, Subrahmanyan Chandrasekhar got involved with their own ideas and built up the foundation of the Blackholes as we now know of.
Blackholes are nothing but the core of a collapsed star. When a star runs out of its fuel, if the star mass is somewhere between 10 – 13 (minimum) solar masses then the stars death would lead to the formation of a black hole. How exactly are Blackholes formed again?. There is a constant battle between two forces in a star, the gravitational force and the force produced by nuclear fusion. What is fused in a star? What makes a star? Hydrogen is THE most abundant element in the whole universe. Due to gravity, the hydrogen molecules fuse up together resulting in the formation of helium and electrons. When the molecules are fused, some energy is released in form of heat which results in the production of light. This reaction when occurs in huge amount, huge in the sense in billions, leads to a formation of a star, which as we see, constantly emits heat and light. A star can only exist as long as they are fueled by hydrogen and helium. Once they run out, the gravitational pull of the core would force the star to implode inside. At the stars death, gravity wins the battle. The outer layer of the star explodes and the debris would we spread all across space, but the star’s core would implode within with immense gravitational pull. The gravitational pull of the Blackhole is extremely strong that, not even light can escape it. Light, which travels 299,792,458m/sec, would literally get sucked inside the black hole.
Blackholes, they bend space and time around it, they are like a hole in the fabric of space. There is an area, much like a boundary around a black hole known as an event horizon. If an object is behind the event horizon, there is a maximum possibility for the object to escape the pull of the black hole. If the object is on the event horizon, only with sufficient speed and force the object can escape its pull. Once the object passes beyond the event horizon, there is a zero possibility for it to escape it. The gravitational pull of the BH is so intense behind the event horizon that anything that enters that region gets spaghettified i.e. it gets elongated stretched into tiniest of the subatomic particles which finally gets sucked into the everlasting darkness of the singularity of the black hole. If you are near a black hole event horizon, you could feel the intense gravitational pull near your legs, when you are at the black hole you can see the back of your head due to the spaghettification.
If Blackholes are black, how are we trying to view them? In the last papers, Stephen Hawking himself said that Blackholes are not black, but slightly grey in colour? Why is that so? It occurs due to the phenomenon is known as Hawking radiation. Hawking radiation states that black hole releases some radiation due to an occurrence of quantum effects near the event horizon. So what exactly are those quantum effects? The radiation is formed due to continuous creation/annihilation of particle and antiparticles near the event horizon. Due to this effect, it is said that Blackholes would lose their mass and energy and would finally vaporize into the quantum realm. Micro black holes are predicted to be larger emitters of radiation than larger black holes and should shrink and dissipate faster. Hence they undergo hawking radiation, they have an outer glow which is expected to be of grey in colour.
Micro Blackholes, where did they come from? There are various types of BH’s, micro Blackholes, stellar mass Blackholes, intermediate Blackholes, supermassive Blackholes. It is predicted that micro Blackholes do exist, experiments are being conducted at CERN laboratories and are being said they observed a few fluctuations. Even though if they exist, it may not be possible for us to view it as they would evaporate instantly. Stellar mass BH’s are the BH ’s which are of 5-100 solar masses;(1 solar mass= 2×1030 kg. intermediate BH’s mass would range from 100-1 million solar masses and supermassive BH’s are almost immeasurable using solar masses. Theoretically, the supermassive BH’s (SMBH) would support the gravitational force exerted on us, hence we could travel inside a BH. Almost every galaxy has an SMBH at its centre. Even our own galaxy has an SMBH named Sagittarius A*. The event horizon team is trying to view that BH which is at the centre. Why can’t they generally vie? Moreover, what is even the event horizon telescope? Event horizon telescope is a project to create a large telescope array consisting of a global network of radio telescopes and combining data from several very-long-baseline interferometry (VLBI) stations around the Earth. The aim is to observe the immediate environment of the supermassive black hole Sagittarius A* at the centre of the Milky Way, as well as the even larger black hole in the supergiant elliptical galaxy Messier 87, with angular resolution comparable to the black hole’s event horizon. This is a major milestone for humanity and a major challenge for Einstein’s equations.
What exists inside a Blackholes? BH’s are like the hole in the fabric of cosmos. They are expected to be of higher dimensions. Hypothetically there are few theories that BH’s act as a bridge to other galaxies or maybe even to other universes. They may act as wormholes. Hypothetically, they predict that the opposite of BH’s would be white holes, which would be at other ends of universe spurting out the tremendous amount of energy, which was released by the BH. Maybe, those white holes may be extremely massive that they led to the formation of a universe. Even the big bang started from a singularity. There are chances but there aren’t any proofs to prove any of the above.
Blackholes, why are they important? What are the quantum effect and fluctuations which would occur? What is a black hole universe? Are we living in one? Where does the information go? Does multiverse exist? What does string theory propose? Is there any chance that an alien civilization is harnessing the power of a black hole and survive? How advanced would they be? What happens if a black hole appears nearby earth? Would we die? (in short, yep) Many more questions which are waiting to be answered.