Black Hole Information Paradox Explained

Introduction 

Blackhole is one of the most mysterious objects in our universe. These are places in the space where the effect of gravity is so much that our current physical theories break there. Until 14 September 2015, there was a question mark on their existence because till then they used to exist only in theories. There were some people who believed that no such thing as a black hole exists in this universe. When people first detected Gravitational waves on 14 September 2015, it became clear that black holes are not just our blank dreams but black holes really exist. But till now we have been unable to understand them fully, due to which we cannot say for sure how this universe evolve or what will happen with it. If we want to know what will happen to us in the future, then it is also important for us to understand how black holes work. This is why scientists around the world are giving so much importance to it.

 Black Hole Information Paradox 

Till 1974, black holes were not paradoxical for us because we only knew about them that these are the only places in the space where gravity is so intense that even light cannot cross from there. That is, once an object crosses the event horizon of a black hole, then it is impossible to return it. That is,  the event horizon is a closed surface in which everything is trapped forever.

But in the year 1974, Stephen's Hawking showed the whole world that black holes have their own temperature which is inversely proportional to the mass of black holes. That is, if the mass of a black hole is high, then its temperature will be reduced and vice-versa. Because of this temperature, black holes always emit radiation, which is called Hawking's Radiation. Due to this emitting Hawking radiation, black holes which have nothing to swallow, lose their mass slowly and at last, a time comes when they cease to exist completely. It is also called black hole evaporation like the way the water starts evaporating completely due to the steam being formed. The black holes are completely destroyed due to emitting radiation, only the hawking's radiation is left. Meaning that after the black hole is over, we do not have any information about which objects this black hole was made of, that is, the information is completely lost. This theory was theoretically and mathematically true, but it gave rise to a Paradox which we know today as the black hole information Paradox.

Understanding of Black Hole Information Paradox 

According to what we have understood so far, there are only two principles that apply everywhere in the universe, the first of which is QUANTUM DETERMINISM which says 'for a given present wave function, its future changes uniquely determined by the evolution operator' and The second is REVERSIBILITY which says 'the evolution operator has an inverse meaning that the past wave function is similarly unique. In easy language, they say that every unique initial state always ends with an Enrique end. It can never happen that two different initial states have the same final state. That is, the information never ends, it is always safe. Let's take an example for better understanding, Suppose you have a book. As long as this book is safe and there is information in it, what will happen when you burn it? 

After burning, you only have the ash left of that book. If some of you say that the information is lost here then you are wrong. As already stated, information can never be lost. If we talk about this example then we have only ash. Theoretically in this example, if we assemble the remaining ash and smoke in exactly the right order, then we will get that book back. Usually, this does not happen but theoretically, it is possible that even after the burning of the book, its information is not finished.

So far we have known that information is always safe which makes our universe deterministic. That is, by looking at the final state of any experiment, we can tell about its initial state and vice-versa. Will arise because it will violate the law of nature. The same thing happens with black holes.

In the physics community, black holes have always been an important question and that is "Do black holes have hair or not?" Opss !! What is it's means? Lets know about it.

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Whatever big objects you know about, they are quite complex. For example, if we talk about planets, then any two planets may be somewhat similar, but there is absolutely no way that both are completely carbon copies of each other. This is because they have many properties that make them different from each other. The two planets must have the same composition and density at each point in order to be a carbon copy of each other. It means to say that every object present in this universe is definitely different from each other on the basis of some property. The properties that make them different from each other have been called hair, but if we talk about black holes, then they have only three properties, mass, electric charge, and spin. This means that if these three things were the same in two different black holes, then both of them would be called carbon copies of each other. That is, there is no way that we can uniquely identify two black holes, so many physicists believe that black holes have no hair.

We know that the objects that black holes swallow inside them include stars, satellites, dust, light, etc. All happen. Now if we talk about the information contained in all these, then they will be mass, size, shape, color texture, spin, composition, pressure, electric, charge, amplitude, wavelength, etc. Now if we talk about the information contained in black holes, then we get only mass, electric charge, and spin. That is, when the black hole swallows those bodies, the rest of the information is lost and when it is completely exhausted due to hawking's radiation emissions, the remaining information is also completely lost. That is after these are over, we cannot tell how the black hole was formed and how it had swallowed the objects inside. Meaning that by looking at their final state, we cannot tell about their initial state which violates the law of nature. Because of this, we call it the black hole information Paradox.

Ever since Stephen's hawking gave his theory, this paradox has been a major debate point for physicists. There are many solutions to this paradox that have been given by different physicists, but there is definitely a big problem with every solution, due to which this paradox has not been solved yet.

Why physicists are in hurry to find the solution?

Actually, as far as we have understood nature, we have come to know that on the basis of a unique state, we can tell about its past or future. But the black hole remains an unsolved puzzle for us because we cannot tell about its initial state based on its end state. Similarly, neither the General Theory of Relativity nor Quantum Theory works in the case of the singularity of a black hole. Meaning that until we fully understand the black hole, we cannot understand the behavior of this universe and until we understand the behavior of this universe with accuracy, we will not be able to tell what this universe was like before and How will it be in future? So far whatever we have read about this universe is just theories. If we are able to understand black holes completely then we will be able to predict something accurately.

Conclusion 

Black holes make us feel that whatever we know till today and so far is not enough. That is, a lot or almost everything is left about which we do not know at all.