THE JOURNEY FROM INFINITY TO SINGULARITY:STEPHEN HAWKING

THE JOURNEY FROM INFINITY TO SINGULARITY: STEPHEN HAWKING

14^th March 2018, the day that shook the whole scientific community around the globe, the death news of, one of the most genius brains ever seen by the 20^th-21^st century, Stephen Hawking……Undoubtedly many of us know this name and his profession, but many of us don’t know how this man who sat on a wheelchair and used a voice synthesizer and revolutionized the whole world of physics for his theories on black holes and Hawking Radiation, Singularity of Gravitational waves……

Interestingly this great personality was born on the 300^th death anniversary of Galileo Galilei and passed away on the 139^th Birth anniversary of Albert Einstein.

Let’s all now try and understand what this man had actually in store for earth…..

Stephen William Hawking was an English Physicist born on 8 January 1942, diagnosed with motor neuron disease at a very young disease, Hawking was wheel chaired for the rest of his life, and used to speak with the help of a voice synthesizer that spells out 1 word per minute.

Hawking was greatly interested in the fields of cosmology and astrophysics, he developed his initial thesis during his Post-Grad studies at Cambridge.

Understanding some of his theories about black holes and discoveries step by step is interesting.

WHAT IS A BLACK HOLE?

A region of space having a gravitational field so intense that no matter or radiation can escape.

It starts with general relativity: the theory of gravitation that Albert Einstein devised in the 1910s to replace that of Isaac Newton.

IDEA OF ORIGIN OF BLACK HOLES

Inferring from his famous law of Gravitation, Newton has assumed and proposed that the massive bodies created a field around themselves, similar to a magnet, and this force is responsible for the diffusion space, and also enable to exert this force on the objects at its surroundings.

This force was later renamed as Gravity.

Einstein later on in his theory of relativity argued that gravity isn’t a field in space, but a property of space, according to which any large massive body like the sun create distortions in the space and cause the space around them to curve up, this distortion affects the motion of nearby objects (This is how the earth revolves around the sun in fixed orbits). One of the predictions of Einstein's theory is that a sufficiently large object, such as a really massive star, can collapse under the pull of its own gravity in a runaway process. All the mass shrinks into an infinitesimally small point of infinite density, called a singularity.

This collapse creates a region of space so severely warped by gravity that not even light can escape from it. We call this a black hole.

But all of this theory was only on paper and many scientists found the idea of singularity bizarre, it was then when Hawking stepped into the scene……………….

HAWKING’S INITIAL IDEAS ABOUT BIG BANG

Hawking started thinking and working about big bang: the idea of universe developing from a tiny speck and expanding continuously. He soon realized that big bang was rather like the collapse of the black hole in reverse.

Now what does Collapse of black hole in reverse mean? To put it in simple words

A black hole absorbs everything that comes near it and finally becomes a singular point: Ultimate Destruction maybe, on the contrary

A white hole that originates from a tiny speck and which cannot be entered from outside but from inside, expands continuously.

Now we can guess how a white hole, the reverse of a black hole maybe connected with big bang.

This lead to the first idea of existence of singularity.

DEVELOPMENT OF THEORIES ON BLACK HOLES

Hawking then realized that the mass of black holes was always increasing rather mass as they swallow up all the matter around them, like an inflating balloon they would get bulgy and bulkier. Thus, he concluded that a black hole would only grow come what may, and he also argued that as per physics there is only one quantity that would always grow and it is ENTROPY.

           WHAT IS ENTROPY?
A thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system.

 According to the second law of thermodynamics, the total entropy of the universe can only increase, never decrease. In other words, the universe inevitably gets more disordered as it gets older. Hawking pointed out that these two rules of nature – the increasing surface area of a black hole and the increasing entropy of the universe – were oddly similar.

INVOLVEMENT OF BERKINSTEN AND THE DEVELOPMENT OF HAWKING RADIATION

Bekenstein a young scientist then suggested that the surface area of a black hole's event horizon might be a measure of the black hole's entropy. But that seemed wrong. If an object has entropy, it must also have a temperature. And if it has a temperature, then it must radiate energy, yet the whole point of a black hole is that nothing gets out.

In order to prove him wrong Hawking started searching for evidence and what he found out was quite opposite of the expected and these chains of events have led to the development of the Hawking Radiation, by uniting two different branches of physics none could even imagine the quantum physics and general relativity. Quantum theory is used to describe invisibly small things, like atoms and their component particles, while general relativity is used to describe matter on the cosmic scale of stars and galaxies.

Hawking started to analyze the black hole working using the quantum theory, according to which there is no term called empty space, any kind of dimension or coordinates are always filled and have a constant flow of energy or matter or particles inside them.

LINKING BLACK HOLES WITH VIRTUAL PARTICLES

What are virtual particles?

As per Quantum physics, there are two kinds of spontaneous particles always in existence,

·       One is made of matter and having a positive energy, responsible for creation.

·       One made of antimatter and having a negative energy, responsible for destruction.

These two particles annihilate each other so quickly that it isn’t visible to us, hence we call them  VIRTUAL PARTICLES.

Hawking drew an interesting conclusion by linking these particles with black holes. He concluded that Virtual particles can be considered REAL if they are formed near a black hole.

As earlier mentioned, that a black hole doesn’t radiate energy or decrease in mass, but when virtual particles get involved, we can observe a very mind boggling phenomenon.

When we create a pair of virtual particles near a black hole, there is a chance that one of the two particles might get sucked up by the black hole, leaving the other one isolated. Now say, the negative energy particle is sucked up the net energy of the black hole gets decreased and by the famous Einstein’s equation E=m*c*c also its mass gets reduced and the end result is that black hole radiates energy(lost mass is converted to energy).

This radiation emitted by the black hole is named as Hawking Radiation.

Thus, with the advent of Hawking Radiation, he was able to prove his own initial statements wrong and also explain to the world that black holes can decrease in size or slowly get evaporated and also put an end to the age-old myth of black holes being black.

THE CONNECTION BETWEEN TEMPERATURE, BLACK HOLES & BIG BANG

Hawking conceived a radical new vision of black holes. During the Big Bang, he suggested, some lumps of matter could have collapsed into miniature black holes. Each lump would weigh billions of tons, which sounds a lot but is far smaller than the Earth, and the resulting black hole would be smaller than an atom.

What is Meant by Event Horizon of a Black Hole?

According to the general theory of relativity, there exists a boundary in spacetime beyond which nothing can affect an outside observer, this boundary is known as the Event Horizon.

Because a black hole's temperature increases as its event horizon's surface area gets smaller, black holes this tiny would be hot: Hawking described them as "white hot". They would fizz with Hawking radiation, shedding mass until they eventually disappeared.

And they would not go quietly. A mini-black hole would get hotter as it got smaller, until eventually it would explode with the energy of a million one-megaton hydrogen bombs.

So far it has been managed to find the Hawking radiation in black holes, because the temperature of the black holes would be barely above Absolute Zero and hence the energy black holes emit in the form of Hawking radiations would be very tiny.

BLACK HOLES DESTROYING INFORMATION?

In his later parts of research Hawking has stated that information that goes inside a black hole gets destroyed and shall never return back to the universe. But this had paved way for a lot of controversies.

When light rays or particles pass inside a black hole, they get locked up inside and hence Hawking has concluded that information carried inside a black hole gets trapped inside the black hole and can’t be back.

So, the question now is what happens to the information locked inside the black hole?

1)   It is encrypted and stored inside the Hawking Radiation.

2)   It is simply lost …gone for good.

Hawking initially believed that the information was gone for good, but after a flurry of debates, challenges and questions that this statement was enough to change the entire notion of physics, humans believed in, hawking finally concluded that the information gone into the black holes comes in a crude, corrupted and undecodable format.

HAWKING’S QUANTUM BIG BANG MODEL

In one his famous books “A BRIEF HISTORY OF TIME” Hawking tried to explain the big bang theory against the Steady State Model by formulating an equation that could describe the entire universe, despite his unquestioned brilliance, the equation was insufficient to explain the ultimate origin of the universe.

When the universe was still extremely tiny, less than a billionth of a yoctometre across, quantum theory implies that the distinction between space and time was extremely fuzzy. That means the early universe did not have meaningful boundaries in time or space, even though it was still self-contained. The very concept of an "origin" in time vanishes into the quantum foam.

Undoubtedly Hawking’s discoveries and theories had a profound impact on the understanding of physics, he has revolutionized the entire thought process and mindsets of many youngsters and has set himself as an inspiration to many. It’s really sad that now that the universe has conspired against the earth and has decided to transport him via the fourth dimension into the black hole.