Hawking Radiation!!!

In today’s blog, I am going to explain an extraordinary theory by an extraordinary man on an extraordinary topic.

It all started when a famous British physicist Stephen Hawking studied quantum mechanical phenomenon near the event horizon of black hole in 1974. At that time, he came up with an extraordinary theory that every black hole should constantly emit electromagnetic radiation. Today, this theory is widely accepted and this radiation is called as Hawking Radiation.

In my previous article on virtual particles, I explained how virtual particles are created by virtual fluctuations. If you haven’t read that article then I will recommend that please read that article before reading this article to understand this article in a better way.

How virtual particles are responsible for Hawking Radiation???

Let us imagine that a pair of virtual photons are created near the event horizon in such a way that one of the virtual particle is created outside the event horizon and other is created inside the event horizon. The virtual particle which is created outside the event horizon narrowly escape the gravitational pull of the black hole. But, the particle which is created inside the event horizon cannot escape the gravitational pull of the black hole and get ‘lost’ forever.

Stephen Hawking

Since these are virtual particles they should be destroyed immediately and purely by annihilation. But this cannot happen in this case because one virtual particle is escaped and other one is lost for forever which means they cannot collide for annihilation.

What will happen with the escaped virtual photon???

The answer is something seemingly impossible. It will become a classical photon and leaves the surroundings of the black hole as Hawking radiation.

How virtual photon get energy to convert into classical photon???

Since photon cannot be created out of nothing due to the law of conservation of energy so, this case create a disastrous problem in physics. One does not have to worry about the law of conservation of energy as long as photons are virtual, since they borrow energy of vacuum fluctuations to make these virtual photons.

But, here it is not happening as the virtual particles are not going to collide. So, here Hawking comes to rescue. According to his theory, the virtual photon gets energy to convert into classical photon from black hole itself.

However, this has a surprising consequences. As the black hole gives away it energy to the virtual photons it emits to convert to classical photons, its own mass decreases and black hole starts evaporating. The smaller the black hole faster it evaporates.

That’s why as I explained in my article on the end of universe that if our universe will end with big freeze then at the last, black holes will get evaporated and that will be the last phenomenon of our universe.

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To know basics of quantum world, astronomy and space exploration you can check out my book "Through the wormhole" on amazon kindle.