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. 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 16th 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 17th 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 20th 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)
