XVI(E): Everything in the unverse is made of math-including you and I.

XVI(E): Everything in the universe is made of math-including you I.
              [Contd. A Journey to the Wonderland of Math. by Ajay Kumar Chaudhuri]
             "Man must rise above the Earth---to the top of the atmosphere and beyond ---for only thus he will fully understand the world in which he lives"-------Socrates.

                              The most puzzling and toughest unsolved problem we are posing to say: How is this universe? Why it is so as we are seeing now? How big is it? When and where did the universe come from and where it is going? What is its ultimate fate? How living beings sprang only on the planet like our Earth? Is there any sign of life in any form, whatsoever, in other, near or distant part of the universe? Was there any purpose of creating intelligent species like us? There are lots of such queries.

                             In search of answers to multitude of such queries, we developed a most modern branch of science called “Cosmology”. Cosmology, the study of the universe as a whole, is not only a matter for cosmologists and astrophysicists, but also for mathematicians. At the heart of the cosmology, there’s mathematics and to comprehend the universe, it is not only necessary to observe and measure it, but also to understand its inner workings; it takes only astronomical data but also require a good understanding of the mathematical equations that govern the evolution of the cosmos.

The applications of mathematics in the study of cosmos is so essential and paramount that otherwise we would be remaining some centuries back when we were still thinking the centre of the universe is our Earth, the Sun, Moon, planets, stars --- all heavenly bodies are revolving round the Earth. This idea is seemingly true but out-rightly wrong contrast to what we now know about the universe we live in.

                        Today we know that the universe in which we live is awesomely large, mysterious, full of adventures, perilous yet awfully beautiful. The idea of the universe motivating us to understand may be ascribed to mathematics. For instance, Johannes Kepler first observed the motion of the planets of the solar system then applied math to formulate his famous Laws of Planetary Motion. This is one of the many examples that illustrate the importance of math in our history of science, especially in astronomy and physics.

                      The modern interpretation of cosmology usually refers to the study of the universe in its totality, including humanity. Our interest centred on the endless overhead sky dotted with the specks of twinkling stars- the dazzling stars, the Sun and romantic Moon is, perhaps from the primitive days of evolution of humankind. But recorded history of cosmology traced back to the ancient civilizations such as Egyptian (3400 – 30 BC), Babylonian (4500 – 300 BC) Maya (2000 BC – 900 AD) and Greek (2800 BC – 300 AD). Though, at that time cosmology was known as the subject of astrology and astronomy.

                    Religions throughout the world have used cosmology to explain how a omnipotent being was solely responsible for creating the universe. Hindu cosmology even asserts that the universe we live in is just one of many that have been created and died only to take birth again. Funnily enough, this particular theory is gathering credence in today’s theories on cosmology.

Our Earth is like a fragment of insignificant dust particle suspended in air in comparison to the vast expanse of the universe and we, the human beings, are even most insignificant creatures in it. Curiously enough, we are trying to unravel the mysteries of the universe of which we are only an inconsequential part and asking ourselves – “How did we come here?”

                 The biography of the universe is very startling, full of mysteries, suspense, horrors and boundless beauties. Cosmologists, astrophysicists and scientists have penned jointly this marvelous real-life story of the universe in the language of mathematics. Yet we can enjoy some interesting episodes of that story which began about 13.8 billion years from now.

                This story commenced with the birth of the universe as we are seeing it presently with an indescribable massive explosion all on a sudden of a tiniest particle, like a grain of sand, with enormous heat which is simply inconceivable to us. Because at that moment today’s vast universe was quizzed to a point under unimaginable gravitational force and was lying as an embryo in the womb of that finest particle, imagined as a “Cosmic egg”.

              This theory tells that a massive explosion gave birth to this vast universe, put forwarded in 1940’s, was not acceptable to many contemporary scientists and cosmologists. A renowned British astronomer, Fred Hoyle sarcastically coined the term “Big Bang” to describe such an explosion.

Afterwards many theories have been put forth related to the universe and its birth or beginning, but till now the most acceptable of them is this Big Bang theory.

             So this is the birth of the baby universe. As a human baby cries just after its birth, so also the baby universe cried. No, this is not a make-believe story. It is detected by scientists as Cosmic Microwave Back ground Radiation coming from outer space by the satellite Cosmic Back-ground Explorer (COBE) launched by NASA of U.S.A. in 1989. Even we can hear this cry with our own ears as the hissing sound from our television set when we tune it up a channel where there is no program.

After fiery birth, the universe suddenly began to expand unimaginably with drop of temperature to 10 billion degrees within one second of the explosion. This is termed as “inflation” of the universe. This was really a colossal physical inflation of the space itself. It is continuing even today, though, at a much reduced rate.

           But we know from the law of universal gravitation that each particle of matter of this universe attracts every other particle towards it. So, what is the cause of this expansion instead of contraction? We are quite in dark about it and unable to identify this bizarre force, despite much efforts our scientists have named it in despair “dark energy”. Of course, Einstein predicted in his theory of relativity that the gravitational force sometimes may be repulsive instead of attractive under certain circumstances such as in the case of explosion of the Cosmic Egg causing Big Bang.

         The Big Bang theory tells us that the universe started its life from pure energy and all other forms of energies, as we know today, were transformed from it within an insignificantly small time. (We should remember here: time is assumed to begin at the very moment of Big Bang and is an inseparable part of the universe, according to Einstein’s theory of relativity). Both positive and negative energies of equal amount were produced simultaneously and hence their sum total was zero. Scientists have collected available data of all types of energies, those exist in today’s universe and mathematical analyses of those data reveal that the sum total of them is still zero; utterly unbelievable and strange! So we can say that this universe started from single source with zero energy. Remember once again, the symbol for golden ration phi (Φ), which is a combination of zero (0) and one (I), which corroborates the above inference.

          The first three to four minutes after birth of the universe were critical and eventful; because during this period the most important and lightest element hydrogen was produced in huge amount as high as 75 percent along with the lighter element helium 24 percent and a bit traces of other light elements like lithium. Hydrogen is still the abundantly occurring element and 75 percent of all matters scattered throughout in today’s universe. We have learned that taking hydrogen as basic component other heavier atomic elements up to iron were subsequently cooked in stellar nuclear furnace in the kitchen of the Cosmos. The rest of the elements up to the heaviest uranium were produced by shock waves of exploding massive stars, called “Supernova”.

So the most startling fact is that: matter came into being from pure energy. Einstein has rightly propounded in his theory of relativity that energy and matter are synonymous [Do you remember the simplest and most famous equation of the world E=mc², connecting energy with matter, derived from Einstein’s theory of relativity?].

             It is just mentioned that some heavier elements were first produced by stupendous shock-waves of exploding massive stars. But our notion about stars from our early childhood is that stars are uncountable twinkling specks of light doted in overhead sky. So how can they be massive? Is it not puzzling? In this context let me remind you a famous nursery rhyme which all of us had read as a kid

“Twinkle, Twinkle, little star,

How I wonder what you are!”

Yes, stars are wonders not only to a child but also equally to people of all ages. Gazing at the dark clear night sky, we are lost in vastness of nature and a barrage of questions pop up in our mind: What they are? How far from us? Can we count them? On close look, some appear bluish, some are reddish and majority of them to be yellowish. Why and many such queries

              Our distant ancestors were also equally eager to know about the universe and of course about stars, but they had no means to explore. Now we have invented a tool to unravel those mysteries which is called “Science”. Thanks to Science, thanks to math and modern technologies for providing us with valuable data, many real-life stories of the stars and complementary amazing pictures related to stars.

What are stars? Each of the twinkling specks of light in the night sky as stars is actually an extremely hot enormous ball of fire. Stars born, live and die like us. But how do they born?

They bloom in the field of the cosmos, called “Nebula”. A nebula is a giant cloud (called molecular cloud) mainly composed of hydrogen (75%), Helium (24%), a little amount of some other gases and dust particles gathered from materials blown out by dying stars. They are also popularly known as stellar nursery for growing stars.

Nebulae are beautiful, highly active, busy wondrous things in the universe. Nebula may be of various shapes, sizes and characteristics and accordingly they are also named, such as Cat’s Eye [Pic. No. 31a], Crab, [Pic. No. 31b], Eta Carinae [Pic. No. 31c], Orion [Pic. No. 31d], Pillars of creation in Eagle nebula [Pic. No. 31e], Horse head [Pic. No. 31f], etc. The Orion nebula deserves special mention as it is the birth place of the most important star to us, the Sun.

                                                                                                      

               

                  Pic. No. 31a                                                   

         
                                                                     Cat`s eye nebula.                                            

                                                                               
                  Pic.No 31b.

                                                                   Crab nebula.

                  

               

                      Pic. No. 31c.                                                       

                           

         
                                                                Eta Carinae nebula.

                     Pic.No31d.

                                                                     Orion neulba.


            pic.No31e.

                                                         Pillars of creation in Eagle nebula.


                pic. No31f.

                                                                 Horse head nebula.

                                                            

                                                                         

The birth of a star is due to what is called “Gravitational Collapse” of the molecular cloud in the nebula. Gravitational Collapse means the contraction of an astronomical object due to the influence of its own gravity which tends to draw matter inward towards the centre of mass. Due to this collapse the pressure on the particles of the molecular cloud continue to increase enormously causing generation of heat up to the level of 1.5 million degrees. At this stage the heat of the central core fires atomic fusion converting four hydrogen atoms into a helium atom and radiating light energy in all directions.[Pic. No.32] Now a star, a gigantic ball of fire is born, though we can see this new born star after millions of years after its birth, as light takes this time to come out of the silhouette dense cloud of gas and dust in the nebula. Stars are born out of debris of dead stars like phoenix, the mythical bird. In a true sense we are also made of star dust.

               

               pic. No32.

                                                                Nuclear fusion of hydrogen to helium.

                        

                   An average size star like our Sun requires about 50 million years to be matured from the beginning of the gravitational collapse to adulthood.

                  About 4.6 billion years ago, perhaps there was a supernova explosion of a massive star somewhere very close to Orion nebula in the Milky Way galaxy sending a tremendous shock wave through the molecular cloud of the Orion nebula giving birth to our Sun as an embryo (called protostar) along with some other stars as his brothers and sisters, whom we are unable to recognize now. It is funny that generally stars are born in batches, may be up to the number 50.

Our nearest average sized most familiar star, the Sun is bigger more than a million times than that of our Earth. Many stars are even much bigger than the Sun. But why do they appear so tiny and twinkling? The first reason is their unimaginable distance from us and the other is the envelope of more than 100 Km thick atmosphere surrounding the Earth. How may we have an idea of that distance?

               The dimensions of the cosmos is so large that using familiar units of measuring distances like miles or kilometers, for our practical purposes will be utterly impractical. So we have adopted a novel mode of measuring very large distances by utilizing the speed of light. It is determined that a beam of light traverses nearly 186000 miles or 300000 km in 1 second. So just imagine what will be the distance travelled by that beam in one year! It is nearly 6 trillion miles or 10 trillion km and is taken as the unit of measuring distances – named a “Light year”. It has nothing to do with a year, it is a distance. The Sun is at a distance of 93 million miles or 150 million km from us. So a ray of light from the Sun will take about eight light minutes and hence we say, the Sun is eight light minutes away from us. In the observable universe, the farthest star we have ever detected is about 55 million light years away.

On a clear, dark night sky, away from man-made lights, standing in dark, if you gaze curiously at the sky, you would see strewn like sea forth on the waves of space overhead. On a close look, you will soon realise that innumerable stars have formed this glowing river stretched across the sky. This is our Milky Way galaxy.

                A galaxy is a massive, gravitationally bound system that consists of billions upon billions of stars, nebulas, an interstellar medium of gas and dust, black holes and the mysterious component dark matter. There are probably more than 170 billion galaxies each with an average, a hundred billion stars in the observable universe. In the expanding space, some galaxies are solitary wanderers while most form clusters and cluster of clusters. What a wonderful example of communal harmony! Galaxies are drifting endlessly in the cosmic dark.

           Astronomers sort galaxies into three main types by their shapes: Elliptical [Pic. No.33a], Spiral [Pic. No. 33b], Irregular [Pic. No. 33c]. If your eyes are apt to study night sky, then you may see some of the galaxies with your naked eye, such as, our Milky Way galaxy, Large Magellanic cloud, Small-Magellanic cloud, Andromeda Galaxy, Triangular Galaxy, Messier 83 and a few others.

                Pic.No33a.

                                                       The giant elliptical galaxy ESO325-G004.

                    

              Pic.No33b.

                                                         The Milky way galaxy.

                    Pic.No33c.

                                                            

                   

                                                            Irregular galaxy--NGC1427A

                   

                   The Sun is an ordinary star of the large spiral galaxy Milky Way having several arms. The shape of this galaxy closely resembles the satellite image of a severe cyclonic storm.  It is a little more than one lac light year across and roughly 1000 light year thick. At least two hundred billion stars were born here and the process of birth is still going on.

                 The Milky Way galaxy is our home in the universe [Pic. No. 33b]. The galactic centre, means the centre of this large disc-shaped galaxy, is 27000 light years from the Earth. Crowded by stars, the brightest bulging portion of the central hub is the kingdom of the dreaded demon, Sagittarius A^*, the   black hole. The Milky Way began forming about 12 billion years ago and is a part of about 50 galaxies, called the Local Group. The Andromeda galaxy, nearest to us, about 2500 light years away, is part of this group as are numerous smaller galaxies, including the Magellanic clouds. The Local Group itself is part of a larger gathering of galaxies called Vigro Supercluster of galaxies. If the apprehension of the cosmologists comes true, then the Andromeda galaxy is expected to collide with the Milky Way around four billion years from now. Then two will eventually merge into a single new galaxy and will be named as “Milkomeda”.

                   Though there are about two hundred billion stars in the Milky Way, we can see at most 5000 to 7000 stars; because the shape of the Milky Way is like a disc and we remain well within it, moreover diffused inter stellar gas, dust and nebulae within it obstruct our vision.

                  Our Earth is an ordinary planet of an ordinary star Sun, one of the two billion stars in the Milky Way galaxy. If the galactic centre is assumed to be our capital city in the Cosmos, then we live in a small isolated village, called Earth, in the Orion Cygnus spiral arm of the Milky Way galaxy, at two thirds distance from the blazing heart of the city.

                The planet Earth with its blue skies, oceans of liquid water, lofty mountains, murmuring rivers, soft meadows, gentle breezes is a world rippling with life. It is a uniquely safe and lovely place for us to live.

               To remain afloat and in safe position in the vast Cosmos, planets of stars are born along with the stars as a rule of nature rather an exception. There are a few stars without any planet, but they born in twins and orbit each other to be in safe position in space.

              The numbers of planets of different stars are different. It is observed that stars may have six planets on an average. Now there are about 170 billion galaxies, each has at least one hundred billion stars, each star has six planets. So what will be the number such planets in the universe? A stupendously large number! Definitely surpass the total number of sand grains on the entire sea shore of the Earth. So the questions which shake our mind tremendously: Are we alone in such a vast universe? Is there any sign of intelligent life like ours or otherwise or any form whatsoever in the near or the farthest corner of the universe? We are trying frantically to explore all possibilities to get an answer of this question.

              In the society of stars there are many inequalities regarding size, body-mass, temperature, brightness etc. All these parameters depends on how much gas (mainly hydrogen), dust and other matters the star collected from its mother, the molecular cloud, at the time of its birth. There are stars which are enormously large and at the same time some are pretty small in comparison to our Sun. So we should know the bio-data* of the Sun at first. It will be of immense help to us for comparison of other stars

[* Bio-data of the Sun:

Present age                           :     About 4.6 billion years.

Place of birth                         :     Orion Cygnus nebula in the Milky Way galaxy.

Distance from the Earth        :     93 million miles or 150 million km.

Radius of the ball of fire       :     689000 km.

Size                     :    About 1.3 million times or 1300000 times that of the Earth.

Body mass          :    1.9891 x 10³⁰ kg or put 26 naughts after 19891 to get the mass in kg.

Temperature      :    at the centre of the nuclear furnace                 :     15 million degree Celsius.

                           :    at the outer surface (called photosphere)        :     6000 degree Celsius

                           :    average temperature on the Earth’s surface   :     15 degree Celsius

Brightness          :    3.287x10²⁶ watt

                               or as if there are burning at a time 1000 watt lamps of a number we get by putting twenty naughts after 3287 ]

The smallest star is about one-tenth of the size of the sun and the largest, so far detected, as Eta Carinae, is about 150 times. In the ancient times, of the history of stars, there were giant stars about three hundred times that of the Sun; but they have extinguished long ago like the monstrous dinosaurs on the primitive Earth. Stars have generation like ours. The Sun is labeled as a second or third generation star.

                   In the society of stars there are stark inequalities in wealth of precious life sustaining fuel, like gases (mainly hydrogen and some helium), dust and some other matters acquired from mother molecular cloud during birth. Stars burn their fuel to remain alive and die when all the fuels are depleted.

                 Our Sun is expending 4 million tons of hydrogen per second for the last 4.6 billion years to provide heat and light to its entire solar family and has already shed a mass of one hundred times that of the Earth. Its present reserve can make it alive for about 6 billion years from now. Then the fateful day will come; Sun will be dead. Will our Earth be lifeless then?

               Stars whose masses are one fourth to less than half the solar mass are the poor stars, called “red dwarfs” and they are most abundant in the universe like the largest number of poor people in our world. But they live a very long life of about one trillion years, even the smallest may survive up to 12 trillion years. The secret behind it, they burn their entire reserve of fuel very slowly. In the process they will gradually be dimmer and dimmer.

             Tiny red dwarfs may have an extended lifetime but they cannot escape death as their supply of fuel will be exhausted certainly on a certain day. At this stage they will die and dead body will be called “White dwarfs”. Eventually the white dwarfs will radiate away all of their heat and become “black dwarfs”. Though we have met with the white dwarfs but not yet the black dwarfs, for it will take time longer than the present age of the universe of about 14 billion years.

Once the renowned British writer Samuel Johnson remarked, “Man alone is born crying, lives complaining and dies disappointed. But the stars as oppose to humans, are born shining, with hundreds or more brothers and sisters, shine ever more brightly over their lifetime and die in a spectacular fashion.”

               If you look up into the sky, you will see that stars are twinkling in different colours. So stars have colour discrimination also, though without any communal prejudice or racial bigotry unlike humans. From this colour we can get idea of its temperature and age. Blue stars are hot and young; yellow stars are conventional and middle-aged; red stars are of older age and waiting for death; and small white and black stars are in the final pang of death.

            Deaths of all stars are not alike. The poorest of the poor stars, the red dwarfs, die slowly, quietly a cool death. While deaths of stars larger than Sun, rich and very rich so to say, may be violent, eventful and very spectacular. The Sun-like stars are of middle class group. They will embrace death not violent, but with brilliant colours.

          When we look around us from this distant little corner of the Milky Way we see many stars surrounded by “Planetary nebula”, though it has nothing to do with the planets. A planetary nebula is created when a star blows off its outer layers after it has run out of fuel to burn. These outer layers expand into space, forming a nebula --- the nursery for breeding stars of the next generation. Around 1780’s the famous British astronomer (German by birth) William Herschel discovered this cloud with his telescope much inferior than today’s version. Though his idea was not correct, yet this name has been retained in honour of the great astronomer.

              When we see a planetary nebula around a star, we may surmise that there is a star, either dying or is already dead at the centre of that spherical shell which was once vibrant with activities of a star with his family of planets and their satellites but they are all now dead. The only remnant is the ghost of that star surrounded by a spectacular colourful glow.

            Sun-like stars are in the middle class group regarding wealth of reserved fuels, chiefly hydrogen and some helium. Unlike red dwarfs they can consume only one-tenth of their stock. The estimated life span of our Sun is about 10 billion years. Now it is in its middle age. After six billion years from now, all sorts of fuel of the Sun will be exhausted. It will be the beginning of the end of the life of the Sun.

                 Then the Sun will undergo a major change. Its exterior layers will continue to expand and cool. Its atmosphere will be drifted into space in the form of a brisk gale and the Sun will be a giant ball turned red from its usual colour yellow, called “red giant”. Its volume will be about 250 times that of the present state. The radius will be 150 million km.

               At this stage, the blazing flame of the red giant will swallow the nearest planets Mercury and Venus and perhaps our Earth also. Then ice on the poles, Arctic and Antarctic, will melt flooding the coasts of the world. The oceans will begin to boil releasing more and more water vapour into the atmosphere which will increase cloudiness shielding Earth from the ire of the red giant. But catastrophe cannot be avoided. Eventually atmosphere will be evaporated away to space and disasters will loom large on Earth. At last death knell for Earth will be heard.

              In this scenario many mind boggling questions arise: Shall we be extinguished then from the Earth? Or our descendants, in the meantime, will either be able to find some ways to escape annihilation or modify themselves to cope with the hostile nature? Will they be quite different from us then?  Or they simple leave this planet forever to the nearest red planet Mars or to a place having some resemblances with our Earth, like Europa- the satellite of the planet Jupiter or even to Titan, a moon of the Saturn? Or move to a suitable planet or satellite of a star nearby? We are to wait about six billion years for the most probable answers of those questions.

           In its death pang of the red -giant phase, the Sun will pulsate slowly expanding and contracting once in every few thousand years spewing its atmosphere in concentric shells of gas. These shells will be flooded by lovely red and blue fluorescence caused by ultra violet light from the naked hot core of the Sun.

        The outer layers will drift off into space forming a planetary nebula. Most of its mass will go to the nebula. The remaining Sun will cool and shrink to be only a few thousand miles in diameter. The star is now a “White dwarf”, a stable star with no nuclear fuel. It radiates its left over heat for billions of years, when its heat is all dispersed it will be cold, dark a “black dwarf”. It is nothing but the corpse of, once burning at 15 million degrees of temperature, emitting heat, light and providing all sorts of energies to the entire solar family, our Sun. This fate is not only for our Sun but also for all Sun - like middle-sized stars of mass up to eight times that of the Sun, though it depends on the mass of the skeleton of the star left after giving away all its matters to planetary nebula and all nuclear fusions in it are stopped.

            If it is less than 1.4 times the solar mass, the ultimate destiny of that star will be   a white dwarf and then finally a Black dwarf. But if exceeds this limit, then the star will embrace a violent death through stupendous explosion, called “Supernova”. This limit is named “Chandra Sekhar limit” after its discover Subrahmanyan Chandra Sekhar, an Indian American astrophysicist. It was a revolutionary discovery in the field of cosmology and he was awarded Nobel Prize along with William A. Fowler in 1983.

          Stars having mass eight to twenty times the solar mass may be called rich and more than twenty five times as very rich amongst stars. But irony of fate is that fuel-rich massive stars die of starvation much earlier than poor or tiny stars which is contrary to our common belief. The most massive stars live few million years against many billion years a tiny red dwarf lives. The secret behind this fallacy is that the survival of stars is a balancing act of contraction due force of gravitational attraction towards its centre owing to its own mass and expansion of its volume due to force exerted by nuclear fusion at the core. When these two opposite forces balance each other perfectly, the stars are in their rosy days of life (called Main Sequence Stars).

But to thwart crushing inwards due to enormous body weight, a massive star is forced to burn lavishly; moreover it can consume only a fraction, may be one-tenth or even less, of its reserve of fuels. As a result a super massive star dies at a much tender age, living only a few million years.

In the case of a giant star, when all the hydrogen at the core are cooked to helium in its nuclear kitchen, shells of expanding gas surround the helium core. The star now becomes a “super red giant” instead of a red giant. The process of fusion continues further for millions of years to create different heavier elements in stages up to iron. As iron cannot undergo nuclear fusion further, all the activities of the core are stooped. But the overwhelming inward gravitational pressure will rapidly squeeze the core turning the super massive star, may have a diameter of 900 million km, to an unbelievable small sphere of ten to twenty km. in diameter. Under this unimaginable high pressure, the temperature at the core will rise to some billion degrees, may be five billion degrees or more.

In this continuing process of squeezing, a stage will reach when the core of the star will collapse all on a sudden, in the twinkling of an eye, sending shock waves through the collapsing shells of gases and then causing a stupendous explosion liberating energies of such a magnitude that our Sun is unable to give in its life-time. It is a spectacular event, a beautiful fireworks show in space --- it is a “Supernova”. It can be seen as a most bright object in the night sky from a distance thousands of light years but faded away in some weeks or months.

                   Supernova has triggered many changes in this universe. Stars give away almost all of their masses to the interstellar space through Supernova as giant molecular cloud which forms nebula, the nursery for growing stars. There are many famous nebulae created from the ashes of super massive stars, like Eagle nebula, Crab nebula etc. where many stars have already born. We owe to supernova for the elements with which our body is made, like nitrogen of our DNA, calcium for bone, iron of blood and the major elements carbon etc. So our seed of life was concealed in the death of massive stars.

            A Supernova occurred last in our Milky Way galaxy in the year 1604, more than 400 years ago. So we are curious to know whether Supernova occurs seldom or frequently in this universe. There are about 170 billion galaxies each containing 100 to 400 billion stars. A conservative estimate by cosmologists indicates that on an average at least 135 Supernovas are occurring per second somewhere in this universe.

          Sometimes stars are born without any planetary system; but then they born in twins, called “Binary Star”, to support each other in space. In that event, if one of them is more massive than the other, then the massive one will be turned to red giant at first and eventually a white dwarf much earlier than the other twin brother. In course of time the less massive one will also become a red giant and may touch some parts of the brother white dwarf. As a result, the white dwarf will begin to steal life – sustaining fuel hydrogen, as available, from the glowing shells of gases of the distended red giant. It gives a new lease of life, at least briefly, to the white dwarf flaring into brilliance. This is called a “Nova”.

           So nova is related to a pair of stars while supernova is concerned with a single massive star. Hence a supernova has nothing to do with a nova.

         The binary star nearest to us is Sirius. It appears as a single bright star in the night sky with our naked eyes. But they are actually a pair of stars which we named as Sirius A and B. In fact, Sirius B, more massive than Sirius A, is now a white dwarf. Sirius A, twice the mass of the Sun, is still a young bright star. Two to three hundred millions of year from now, they were bluish, bright and active two young stars.

          When a star of mass eight to twenty five times that of the Sun, dies in a supernova explosion, its core will be turned in to an iron sphere of radius ten to twenty km. in diameter. The continued gravitational collapse will crush all the atoms of the iron core to neutrons by combining positively charged protons in the nucleus with the revolving orbital electrons. It is the “Neutron Star”. At this stage mass of the skeleton will be about two to three solar mass. Then imagine what will be the density of a sphere of radius 10 km. in which two to three suns are compressed into it. It will be the densest of all matters in the universe. A tea-spoonful of it will weigh some billion tons.

We have not met such a dreaded thing on our Earth, but neutron star’s dust are in our food, in our drink, in the air we breathe and everywhere in the matters around us, as neutrons reside within the atoms of elements except hydrogen.

           The neutron star born by supernova explosion from the super red giant stage of the super massive stars begin to spin as fast as 43000 times per minute, gradually slowing down over time.

During the gravitational collapse of the star, magnetic field increases unbelievably and traps charged particles from which beam of electrons emit narrow beamed radiation as electromagnetic waves including visible light. If the Earth happens to fall in the range of this beam we see a flash for each rotation as a light house beacon sweeps the night sky and hence a neutron star is a cosmic light house. Its beam is called a “Pulsar”. In Pic. No.34 we see a beam of pulsar from the neutron star at the centre of Crab nebula.

      Pic. No.34

                                                         Crab Pulsar in Crab nebula.     

Some neutron stars are quite alone in space, some have companions (a binary star) and even some have planets.

                 The baffling question is that whether the neutron stars will ultimately disappear someday under the continuing gravitational pressure? The cosmologists are yet unable to find an answer of it.

If a star is more than 25 times  or even up to 150 times massive than that of the Sun, as maximum possible mass of a star, estimated by cosmologists, it will be turned to a super red giant and eventually blown off in a supernova explosion with a remnant of a neutron star within a few million years. But since its initial mass so large that it continues to exert massive inward gravitational force on the neutron star. When the inward force overwhelms the repulsive outward force exerted by the neutrons of the core, the core will be squeezed so much that it will became smaller than a pin head. As a result the gravitational field inside will be so strong that nothing, not even light can escape from it. Now it becomes a dreaded demon --- a “Black Hole”.

                It can now swallow everything including stars, galaxies and all matters and particles which enter in the jurisdiction of its kingdom called “event horizon”. All of these things are attracted towards its centre in a vortex as a rotating disc, called “accretion disc”. It becomes very hot and emits light which lit the matters spectacularly before they are swallowed by the black hole. Hence though a black hole is invisible to us, yet its surroundings are highly illuminated which tells us its presence. The renowned British astrophysicist Stephen Hawing has suggested that black holes may emit a faint radiation, called, “Hawking Radiation” named after him. So black holes are not really black in a true sense.

                Einstein’s most famous theory of general relativity predicted the existence of the black hole but he doubted it as he was not aware of the truth hidden in his own theory.

               At the centre of black hole there may have been piled up twenty five or more sums. The density and gravity are so enormous that all the laws of physics known to us are of no use. This condition is called “Singularity”.

              Scientists once thought that back holes came in only small and large sizes, but recent research has revealed the possibility for the existence of mid sized black holes for which the astronomers have been looking very hard.

            The smallest ones are known as “primordial” black hole and believed to be formed during the infancy of the universe, soon after the big bang. Though they may be as small as an atom yet their mass may be that of a large mountain.

           The most common type of medium sized black holes called “Stellar”, created by supernova explosion of massive stars. The most of such a black hole can be 20 times that of the Sun and can fit inside a ball with a diameter 10 miles. Dozens of stellar black holes may exist within our Milky Way.

The largest black holes are called “Super massive” whose masses may be greater than one million suns combined and would fit inside a ball with a diameter about the solar system. It is believed that every large galaxy contains a super massive black hole.”SagittariusA^*” is such a black hole remaining at the centre of the Milky Way which we have already seen.

            A perplexing question may peep in our mind, could a black hole may swallow our lovely Earth some day? No, absolutely nothing is there to be worried, as the nearest black hole is more than one thousand light years away from us; moreover black holes do not wander around the universe, randomly swallowing worlds. They follow the laws of gravity just like other objects in space.

A black hole may be imagined as a bottomless pit or a cosmic sinkhole or even as a worm-hole in a fruit, say an apple.  Can we think these gravity tunnels will serve us some day as an interstellar or intergalactic subway to travel to almost inaccessible places in space much more speedily? Can a black hole work as a time machine which will show far off past or a distant future? All these things are nothing but fantasies now, yet they indicate how mysterious this universe may be! [Pic. No. 35 Life cycle of stars]
        Pic.No 35.

 Life cycle of stars

                  Global human population growth amounts to 75 million annually. In the last 200 years, the population has increased by more than 6 billion and expected to keep growing. But the food and other means of our living are increasing at a much lower rate. So the situation is alarming for the future.

As the stars are also born and die like human beings so many of us may be curious to know about the rate of birth as well as of death of the stars in this universe. Cosmologists and astrophysicists have collected the relevant data and performed mathematical operations after analyzing them. In their view, the Milky Way galaxy produced about 3 new stars per year. Considering all the 170 billion galaxies, the average rate of birth comes at only one per year. Surprisingly the rate of death is also the same. It is found that about 640 million stars are born and also die by the same number in a day.

What a wonderful balancing act on population of stars! Perhaps the Mother Nature is very much aware that the amount of the staple food for stars, namely hydrogen and also other food –stuffs are fixed throughout this entire universe, so she has enacted some laws to contain the population of the stars to avoid catastrophe. Will we also obey that dictum?

               As of now, we have travelled in the cosmos viewing billions upon billions of galaxies each of which contains up to four billions stars of different sizes, luminosity and colours; most of them have family of planets with satellites which may harbor life. There are innumerable wonderful nebulae composed of gas and dust, the nursery for growing stars, within the galaxies. There are also interstellar and intergalactic voids where you may feel a temperature of as low as –270 degree Celsius which is nearest to lowest possible temperature of - 273⁰ Celsius in the universe.

These are only some parts or limb of the universe, not the whole of it. If you could peep - outside the universe to see what it looks like, what would you see?

                 Scientists have struggled with this question, taking different measures, exploring different avenues in order to determine the geometry of the cosmos and whether or not it will come to an end.

Einstein showed us the way to find an answer of this long standing question. We have already seen in his general theory of relativity that space is itself curved by a mass. So the total mass of the universe will determine its shape and also fate.

                  Interestingly, scientists have prepare an inventory of the assets of the universe in terms of mass and energy together (as mass and energy are synonymous which is evident from Einstein’s famous equation E=mc²) by applying most modern scientific perception and highest order mathematical skill. They calculated the masses of all perceptible things, such as all galaxies, stars, dust particles, gases, and of course including us, separately and the mass of the universe as a whole. Surprisingly, the sum total of all these things is less than the mass of the universe as a whole. So there is definitely a missing link between the two. The scientists have surmised the presence of a mysterious matter which is neither observable nor perceptible, quite in dark to us and hence they called it “dark matter.”

                   Depending on these findings scientists prepare a list of mass-energy asset of the universe by percent as:

Common matter is 5 parts, dark matter 27 parts and dark energy 68 parts. So sum total of dark energy and dark matter is 95 parts. How horrible the situation is! Only 5 percent mass-energy of the universe is within our reach and the rest are in dark. Then we can say, “Universe! Mystery is thy name’.

We have noticed that the space is expanding by the action of a bizarre force. The scientists have rightly guessed that this expansion might be contained only by the gravitational force of attraction of the matters in the universe. They have also calculated the amount of matter in a unit volume like per cubic cm or cubic metre etc. of the universe, called density. The density which will just counter this expansion of the universe is called “Critical density”. This crucial density is approximately 10 hydrogen atoms per cubic metre.

                   Astrophysicists believe that the ultimate fate of the universe depends on three factors: (1) Universe’s overall shape (2) Its density and (3) How much dark-energy actually exists in this universe.

                  The Big Bang theory of the birth of the universe is most plausible cosmological theory accepted by most scientists. Based on this theory they started to ascertain the ultimate fate of the universe and put forwarded possible ways or theories on it. These theories are actually off shoots of the Big Bang.

So, the shape and fate of the universe depends on whether its actual density is less than, greater than or equal to the critical density.

            If the actual density is less than the critical density, then under the action of the bizarre dark energy, the expansion of the universe will continue. Planets, stars, galaxies and even individual atom will be pulled up so far apart that the stars will have no access to raw materials for formation. Thus lights will go out for good. Cosmologists named this state as “Big Rip”. In this scenario, the shape of the universe will be like a saddle and may be conceived as an “open universe”.

Complete darkness will loom large on the entire universe, the temperature will come down at lowest possible level, which may be called Big Chill. Hence the universe will embrace a chill death in eternal darkness.

On the other hand, if the actual density of the universe is greater than the critical density, then possibly after trillions of year, so far the untamed expansion of the universe will stop by the continuous action of the attractive gravitational force. The universe will begin the process of collapsing in on itself. Now the shape of the universe will be “Closed” like an infinite but bounded sphere.

                 As the process of collapsing continues, the galaxies will come closer and closer, all matters of the universe will move fast towards the centre of that sphere and in a cosmic time scale that great sphere will be squeezed to just a single point --- exactly the replica of the cosmic egg, a state just before Big Bang. It will essentially be a “Big Crunch”.

              So after completing a life cycle the universe will end its life from where it started. Some scientists are of opinion that the universe we see is the result of a cycle repetition of the Big Bang, where the first cosmological event came about after the collapse of a previous universe.

                The third possibility is that the actual density of the universe may be equal to the critical density. In that event, the rate of expansion of the universe will continue to be diminished over an infinite span of time. Then the shape of the universe will be somewhat like a thin and infinite flat sheet of paper. [Pic. No. 36 : Probable shape of the universe where Ω represents critical density]

                             Pic.No 36.

 Probable shape of the universe

                  Another theory on the fate of the universe has been proposed, not too long ago, after the particle physicists could recognize another subatomic particle commonly known as “God particle”. But what is it? It is the nickname of the subatomic particle called the Higgs boson.  In layman’s terms, different subatomic particles are responsible for giving matter different properties. One of the most mysterious and important property is mass. Some particles like protons and neutrons have mass. Others like photons do not. The God particles or Higgs boson believed to be the particle which gives mass to matter. The God particle nick name grew out of long drawn  struggle of physicists to find this elusive cosmic puzzle.

                  Depending on the properties, so far known of this mysterious particle, cosmologists begin to think that our universe might experience a catastrophic event when a “bubble” from another alternate universe appears in ours. If the said bubble exists in a lower energy state than our bubble, then our universe will be completely annihilated, as if with a slurp. This is named as “The Big Slurp” theory.

              These possibilities regarding the ultimate destiny of the universe are almost hypothetical, as there are many ‘ifs’ and ‘buts’ in the backdrop. As the speed of light is only absolute in this universe and has a speed of 300000 km per second, so our vision has been restricted. About 14 billion years have elapsed after the birth of the universe and hence scientists have opportunity to view this universe up to a maximum distance of 14 billion light years. So we are in dark about the universe beyond this distance.

Moreover, the dark energy is playing its tricks on this universe in a clandestine way. We have no idea about what role it will play in future. Will its amount remain the same in the distant future or will decrease with the passage of time or will it disappear all on a sudden as it appeared suddenly?  

We are searching answers for those frantically, as the ultimate fate is not concerned only with the universe but also for our so beloved Earth and finally with our survival.

                Some perplexing questions are also chasing us: How and why have we come on this Earth at a remote corner of the universe? Why this universe is so as we are observing it? Have we any role to play in this vast universe? Was there any place for us in the blueprint of the creation? There are many such other queries.

              Being a most insignificant part of this vast universe, we are trying to unravel its great mysteries, strive to fathom into the laws governing the entire universe and endeavour to find answers of those perplexing questions.

            The Big Bang theory regarding the birth of the universe seems most credible to us. It tells us that about 14 billion years ago whole of this universe was lying as embryo in the cosmic egg, just like a very big tree remains asleep at the core of a tiny seed. So, we may argue that each and everything in this universe has originated from a single source and hence closely related to each other by birth. Hence we may arguably think that we are in a close relation to those billions and billions of stars burning at millions of degrees of temperature at a distance of millions and millions of light years away from us. Not only those stars but also their galaxies bearing nebulae, the innumerable planets and satellites revolving round those stars in the vast expanse of space are in an inseparable relation with us.

             So, the message of the universe to us is of equality, unity and oneness. There will be no conflict of colours, creeds, religions, rich and poor if we can remember that all of us were born from the ashes of dead stars.

           The Big Bang theory also tells us that this universe took birth through the explosion of a tiny particle. So, the question is:  Where is that centre of explosion today? The reply is: That point may be within me or you or anywhere or everywhere in today’s universe. Then I think with conviction that though I am insignificant yet not, irrelevant in this universe.  I am a part of it and have immense potentialities.

          Another cosmological puzzle to us: How did we appear on this Earth? Scientists believe that life sprouted on the Earth in the simplest form as bacteria in the water accumulated on the cracked skin (today’s sea) of the young daughter of the Sun of one billion years of age. Then through some hundred millions of year of evolution we came to our present form. But the greatest wonder is: How seed of life was first sown into inert matters! How consciousness, intelligence came into being within us by what we are observing this beautiful universe, try to discover the stringent rules of the cosmos? We have found our address amongst the stars in vast space. We are trying to decode the mysterious space.

                 We are spectator, investigator, and researcher at the same time. Perhaps that beautiful creation would have been incomplete if we were not there to appreciate it. So we were very much there in the blueprint of the creation of this universe. Therefore though we are insignificant, have little capabilities yet we are not unworthy in the vast scenario of the cosmos.

                We are in quandary about the ultimate fate of this universe. Belying all hopes and despairs, if death is the ultimate destiny of it, will it be an end forever of this wonderful creation?

It is accepted by a majority of school of scientists and cosmologists that this universe was originated from a tiny particle where all the energies of it were stored up which were set free from the captivity through the Big Bang. Then after, energies are driving this universe, matters came up from energy. Einstein has incredibly found a relation between matter and energy in his special theory of relativity.

It is known undoubtedly that we can neither create nor destroy energy. It can only be transformed from one form to the other only. Then the question that shaking our mind vigorously is: In the event of death of this universe, will energy also be perished?

                  Let us look 14 billion years behind moving in the reverse direction of time wading through the darkness of the past to reach just before the moment of occurrence of the grand event of Big Bang. Now if we ask: How long the baby universe has been in incubation in this cosmic egg? Was there anything like “time” as we know today? Was there any past? If so, how was that?

Science is mum about it, Scientists are utterly helpless to give an answer. To find an escape route from such a predicament, we think over of an omnipotent someone who is playing this game of birth and death of this creation. Famous scientists are no exception which will be amply clear if we go through some quotes of some famous scientists.

               The 16^th century Italian scientist and scholar Galileo Galilei made pioneering observations that laid the foundation for the modern physics and astronomy. Such a famous scientist said, “Mathematics is the language with which God has written the universe.”  

            Sir Isaac Newton, an English mathematician, astronomer and physicist of the 17^th century who is widely regarded as the greatest scientific genius the world has known. Yet he spent less time on science than on theology. He spent a lot of his valuable time in reading the Bible. He was a devout Christian and a great believer of God. Once he remarked, “He who thinks half- heartedly will not believe in God; but who really thinks has to believe in God”.

             Albert Einstein, a German by birth is esteemed as the greatest scientist of the 20^th century who believed in the role of God in creation of this universe and said, “I want to know how God created this world. I am not interested in this or that phenomenon, in the spectrum of this or that elements. I want to know his thoughts. The rest are details.”

                Another great scientist of today Stephen Hawking, an English theoretical physicist and cosmologist is of view, “However, if we do discover a complete theory, it should in time be understandable in broad principle by everyone, not just by few scientists. Then we shall all, philosophers, scientists and just ordinary people, be able to take part in the discussion at the question of why it is that we and the universe exist. If we find the answer to that, it would be ultimate triumph of human reason – for then we would know the mind of God”

                     So it may be presumed that the theology and science are not hostile but may be supplementary to each other which are echoed in Einstein’s famous quote relating religion and science: “Science without religion is lame, religion without science is blind.”

Therefore at last we may conclude that, the greatest mystery of this universe to us is the mysterious mind of its creator.

                                                                                                                              [To continue]

Reference Internet: All the images are taken from Public Domain (except otherwise stated)

Image credit:                               Image No.31a : Cat`s eye nebula---NASA and ESA. (https://en.wikipedia.org/wiki/Cat's_Eye_Nebula#C)
                                                               No.31b  : Crab nebula----NASA and ESA.    (https://en.wikipedia.org/wiki/Crab_Nebula)

                                                               No.31c:Eta Carina nebula----Creative Cosmos:Attribution:Haren Borel

(https://en.wikipedia.org/wiki/Carina_Nebula)

                                                               No.31d:Orion nebula--APoD-NASA

(https://en.wikipedia.org/wiki/Orion_Nebula#/media/File:)
                                                                No.31e:Pillars of creation in Eagle nebula
credit: NASA, Jeff Hester, and Paul Scowen (Arizona State University) - http://hubblesite.org/newscenter/newsdesk/archive/releases/20.03/34/image/a
                                                                 No31f:Horse head nebula----Creative Cosmos:Attribution:
Ken Crawford  (https://en.wikipedia.org/wiki/Horsehead_Nebula#)
                                                                 No32.Nuclear fusion of hydrogen to helium:Creative Cosmos:Attribution--Borb
(https://commons.wikimedia.org/wiki/File:)
                                                                 No33a:Elliptical  galaxy:NASA and ESA
(https://en.wikipedia.org/wiki/Elliptical_galaxy#/m)      
                                                               
                          
                                                                  No33c--Irregular galaxy:Attribution--NASA,ESA and The Hubble Heritage Team  (https://en.wikipedia.org/wiki/Irregular_galaxy)
                                                          https://en.wikipedia.org/wiki/Crab_Pulsar

       No34--Crab Pulsar:Attribution---NASA and ESA

(https://en.wikipedia.org/wiki/Crab_Pulsar)
                                                                   No35---Life cycle of a star:Attribution---NASA
(https://en.wikipedia.org/wiki/Stellar_evolution#/m)