Everyone on this earth
have that question in
mind which constantly
keeps hitting them like,
tell me, tell me now, how was
the universe created, how did
it actually came into existence,
how are they present here,
how long are they going
to stay here or what
is going to happen in
future with this earth.
But never really got any answer to this,
although according to scientific studies,
there is one theory which
explains some points
that somehow makes answer
valid for our brains.
And this theory is what you
can call as, big bang theory.
You always are taught to believe
that universe is infinite and thus
no one can really find out about
how it ever came into existence,
but this theory made it
somehow proved as wrong.
According to big bang theory, it is
about 13.8 million years ago when
this universe came into existence
and that too as a singularity.
Now, what does this “singularity”
word actually refers to?
Well, there is not any perfect
explanation to this word,
but it is believed that singularity
refers to the zone which can really
disobey the concept of physics that
you may have been studying from years
as it says that singularity
exists in the core of black hole.
You know the hole which is
considered as the areas of intense
gravitational pressure and the pressure
is believed to be so much intense
that it can actually squish up
the finite matter into infinite
density where infinite densities
are known as singularities.
Also, it is believed that our
universe actually originated as
infinitely small, infinitely
hot and also infinitely dense,
but no one actually knows
about where it came from.
And then after that initial
appearance it actually
exploded (what you can also
call as big bang) and cooled,
in more simple language you can say that
it actually transformed from being that
very very hot and very very small to the
current version and gave home to us,
unique creatures on this unique planet.
If you are asking about what
was there before this entire
thing, well the answer to
this is there was nothing;
yes there was nothing at
all according to studies.
Also, there are many other
names that are been given to
this theory, as when it was
initially proposed by Lemaitre,
he called his observation as primeval
atom which was years later changed by
George Gamow as Ylem, also it was once
called as primordial atom and cosmic egg.
History of Big Bang theory
Now, before you take any
step forward about knowing
more on big bang theory
it is important that
you earn about what is
the history of big bang
theory as it will help
in better understanding.
Starting over the history,
what is the first
thing that is needed
to be discussed here,
what gave birth to this big bang theory
or you can say what is the thing
that led to the indication of big
bang theory at very first step?
So, on answer to this, in 20th century
there were some observations made
related to universe or you can say spiral
galaxies by an American astronomer
named as Vesto Slipher which calculated their
Doppler redshift in result the only thing
that was found was that all of the spiral
galaxies were moving away from our own.
Moving forward in the year 1922, Russian
cosmologist Alexander Friedmann through
his examines developed what you may be
knowing by the name of Friedmann equations
and that were that time derived using
Einstein’s equations of general relativity.
Before this, Friedmann discovery
about universe being in the state of
expansion was that pure conflict to
Einstein’s Cosmological Constant
which finally made him believe
that this discovery was not at
all wrong and universe is actually
in the state of expansion.
Then, in 1924 Edwin Hubble’s calculation
of great distance to the nearby
coiled nebula showed that these structures
were certainly another galaxies,
along with which he carried out
with his calculations finding out a
distance between these objects and thus
in 1929 came up with the discovery
according to which there is some
relation between the universe and other
celestial bodies, which is now also
known by the name of Hubble’s law.
And on the other side, in 1927 Georges Lemaitre
(a Belgian physicist and Roman Catholic
Priest) was working upon the equations derived
by Friedmann and that too independently,
as a result of which he discovered
that this distance between universe
and celestial bodies is increasing
because of the expansion of universe.
In 1931 he took this theory forward
and suggested that now if the
universe is expanding, that clearly
indicates if one moves back in time
then what they are going
to find is that universe
actually started from
nothing, well nobody
really knows that but it
is truly believed that
universe at first was
too much dense and hot.
However, there were lots of
discussions about this in 20s and 30s
and lots of critics came forward
to make this theory go false,
also Lemaitre was accused of making
this theory come into existence.
There were some other theories which were
derived at this same time discussion
about how whole of the universe came
into existence and what it is all about,
such as Milne model and
Oscillary universe model
which was derived on the
basis of Einstein’s
theory of relativity
according to which universe
was moving on those definite
or indefinite cycles.
As the World War II got
into rest, followers of
steady state model and big
bang theory were on a
debate and big bang theory
was already into the
air and was grabbing more
and more popularity.
And finally got confirmation
with the discovery
of cosmic microwave
background radiation in 1965
and thus made it come
out as the best theory
about the beginning and
development of universe.
And moving forward, it got to have
that solid base as astronomers and
cosmologists made all of their efforts
between the era of 60s to 90s.
Moving forward, there were number of
modifications made in this theory in
late 90s and 21st century so as to
make it more understandable by people.
In 1988, it was also
found that expansion of
universe is accelerating
which was also supported
by various observations
made by ground based
CMB and many other
galaxy redshift surveys.
Also from years of 2003 to 2010,
NASA took lots of pictures
that were really very
detailed version of universe
and it clearly explained that this
universe is created about 13.8 billion
years ago, as per defined in the
calculations made in big bang theory.
So these positive results
all of the people believe
that there is not any
other theory derived yet
which can explain the
evolution of universe in so
much detailed and proper
manner as done by this one.
Now, the only work that is
been done is upon finding
about that how does these
galaxies emerge when
universe was forming up
and also finding clues
to the concepts of dark
matter and dark energy.
Where does this Big Bang
theory originated from?
Now, you already know that what this
big bang theory is all about and who
were those people having their hands
bringing this concept into light.
Moving forward, there are
many questions which
one got to know about
this theory, among which
the very first one is
to know about where the
big bang theory actually
brought out from.
Talking about this, big bang theory
is the final result of two different
scientific approaches which are
named as astronomy and cosmology,
among which astronomy is carried out
by using those different instruments
which astronomers use to observe
stars and other celestial bodies
and on the other side
cosmology is the study which
is related to astrophysical
properties of universe.
Now, getting into some deep information,
it was in 1800 when astronomers
started experimenting with these tools
which were named as spectroscopes,
a device which scatters light into the
band of its constituent wavelengths.
Basically this tool helped them in
knowing about the kind of elements that
are present in light source all by
looking at the wavelength distribution.
At the same time, there
were two more discoveries
made about sound and
light, according to which
frequency of sound waves
depended upon the position
of the source where that
sound is coming from.
Specifically, which means that if the source
of sound is somewhere near you then the
frequency of sound waves
will automatically
compress and thus it will
be bit louder for you.
On the other hand if that
source goes away from you
then the frequency will
scatter which makes the
volume go low and thus you
hear it with different
pitch, this is also known
as Doppler effect now.
And talking about the discovery
on light, astronomers got to
find that some of the starts are
moving away from the earth.
How? As you know that light travels
in waves too, and thus there
were some scientist who while
studying over their discoveries found
that there are some starts
which had more of their
light falling onto the red
side of the spectrum.
And this shifting of light
meant that the stars are
moving away, as they move away
their wavelengths stretch.
This theory was later known
by the name of redshift.
Now, after these discoveries, later
in 1920, there was a scientist named
as Edwin Hubble who noticed something
weird happening there at the top.
Velocity of star is believed to
be proportional to its distance
from the earth which in other
words can also be said as that;
the distance of the star from earth is
equally increasing as about its moving
away from earth, which made Hubble
to discover that earth is expanding.
Though, there were lots and lots
of discussions on which can be any
possible relation between a velocity
of any celestial body up there
with its distance from the person
standing here watching it from earth.
And, Hubble actually failed in giving that
proper explanation as he provided the
number which was overestimated, according to
the studies made in future on same thing.
This discovery made by Hubble was
later on named by Hubble Constant.
So, Hubble discovered
that earth is expanding
continuously and which
directly states that
billions of years ago this earth was much way
smaller than in which you are living now.
So, basically according
to this theory if you go
long times back then what
you will only get to see
is universe with infinite
density containing all of
the matter of, energy, space
and time of universe.
And so was how big bang
theory came into action.
Like any other theory, this theory also
had some conflicts already waiting
to disagree with this, among which the
most famous one was Albert Einstein.
According to him, earth is static and
the static universe doesn’t change.
He studied many of his theories so as
to get positive results out of it,
but to his surprise according to all
of the calculations made by him
the only thing that came out as a
result was, Hubble’s observations
were correct and thus which were
later concluded by Einstein.
However, this theory and observation gave
rise to many of the predictions some
of which were proved as not valid and
many of them are still talked about.
After some years, during 1960s
discovery of cosmic microwave
background radiation (CMB) made this
big bang theory get solidified.
What is Cosmology?
As you may already know that
Big bang theory is derived
from two concepts that is
cosmology and astrology.
Among which astrology is something which you
all are somehow aware of but cosmology,
well there are some roots that you
still need to know about this concept.
So, cosmology is that concept
of physics which studies
about the beginning and
ultimate outcome of universe.
This is not very much far from the
concept of astronomy or astrophysics.
In other words you can also say that
cosmology is something which comes
out by connecting the performance
of largest structures in universe
(like planets, galaxies, stars
and galaxy clusters) to the
smaller ones, basically the
particle matter in the universe.
If you look upon the history of this concept
of physics, it is actually believed
that this is one of the eldest forms
of hypothetical enquiry into nature.
This is believed to became into
existence when in history some
ancient human looked upon a sky
and thought about the questions
like how they are
existing here or what is
happening there in the
sky or are they alone in
this universe or maybe what are those shiny
things that are twinkling in the night sky.
To find answers to which there were
many of those good attempts made.
Chief among all of those
ancient people in the western
technical tradition is the
physics of the earliest Greeks,
who established an inclusive
geocentric model of the world which
was studied and worked over the
eras until the period of Ptolemy,
at which point cosmology actually didn't
grow further for numerous centuries, apart
from some of the facts about the speeds
of the several mechanisms of the system.
The next most important change
or one can say improvement in
this part originated from Nicolaus
Copernicus in the year 1543,
when he issued his paperback related
to astronomy on his deathbed
outlining the indication for the
heliocentric model of the solar system.
The basic vision that brought out this
transformation in thinking was the
concept that there was not any of the
real reason which can prove to be helpful
in assuming that the Earth
comprises a fundamentally
privileged spot within
the physical space.
This major change in conventions is
termed as the Copernican Principle.
Copernicus' heliocentric model developed
even more popular and accepted by all
of the efforts made by Tycho Brahe,
Galileo Galilei, and Johannes Kepler,
who gathered substantial
experimental indication
in provision of the Copernican
heliocentric model.
And then all of these discoveries
were used together by Sir Isaac
Newton who gave a proper explanation
about planetary motions.
He was the person who had
this unique instinct and
vision to recognize that the
motion of those objects
that are falling to the
earth was somewhat related
to the motion of those
looping around the Earth.
And as the motion was comparable,
he discovered that it maybe
probably because of that same
force, which he termed as gravity.
So, by making that careful observation
and the expansion of a new
arithmetic called calculus and also
using his three laws of motion,
Isaac Newton finally succeeded
in making up the equations that
were able to describe the motion
in a variety of circumstances.
Now as this gravity law theorized by
Newton, made it possible to predict
the motion of particle out there
but, there was still one problem,
according to which still it
wasn't accurately clear to
anyone that how it was
actually functioning that way.
Though according to the theory
it was anticipated that
objects with mass fascinate
each other through the space,
but there was not any clear scientific
explanation to this statement
by which Newton could explain this
whole of the mechanism of gravity.
And so in account of
explaining this mystery,
Newton trusted upon that
basic appeal to God –
according to which objects out
there are behaving this way
because of the God's perfect
existence in that outer space.
And thus for finding that physical
description they have to wait
for over two centuries, until
the advent of that mastermind
and who proved out to be Albert Einstein
who with his theory of general relativity,
took a step forward to redefine this
scientific understanding of gravity.
According to Einstein's new
invention, gravity was formed
as a result of the twisting
of 4-dimensional space-time
in reaction to the
occurrence of a huge object
that can be a planet, a
star, or even a galaxy.
The most important fact
which came out of this
formulation by Einstein
was that space-time
itself was not in
stability which basically
means that it will either
expand or contract.
And afire this according to
Einstein universe was everlasting
and so he discovered the cosmological
constant into the theory,
but which later on proved out
to be wrong as according to
Hubble’s theory the universe
is continuously expanding.
So, basically if universe is
expanding then that means if one
pushes off that rewind button
then what they will get to see
is that universe began
from that tiny little
thing which no one
actually knows about.
It is also believed that when scientist
took that deep information about the
evolution of universe and the theory of
cosmic microwave background radiation,
what they got to find is that there
was some problem with same and thus
quantum physics needs to really play
strong to explain this concept properly.
This concept of academic cosmology is also
sometimes known as quantum cosmology.
Now, as the technology has taken various
steps forward and same is the case with
science which means that there are also some
improvisations in the field of cosmology,
but there are some of the mysteries
that are related to cosmology
and are still somehow wavering
around, such as these two:
Dark matter
There are some galaxies
out there which are
operating in a manner
that cannot be completely
explained only on the basis of amount of
matter that they are carrying within them
(which is also known as "visible matter"),
but if there is some of that additional
unnoticed matter within that galaxy then it
can actually become somehow explainable.
Based on those recent
measurements it is found
that this additional matter
that can be found in
the galaxy is expected
to take up about 25% of
space in the universe is
known as dark matter.
Dark Energy
It was in late 1998 when astronomers tried
to notice the rate at which the universe was
reducing down, but what
they found out as a
result was that it was not
at all reducing down.
Instead it seems to be speeding up,
and thus this was the time when
Einstein's formulated cosmological
constant was there to be used at last,
but what they noticed was that universe was
not really at the state of equilibrium but
it was pushing all of the galaxies away and
that too at really really faster rate.
There is no idea about what all is
causing this repulsive gravity to
occur but it is already been named
by physicists as "dark energy."
Now, as you know the concept of
cosmology, it will be easy for
you to understand hole of the
concept of Big bang theory.
That First Second and 13 billion years
By now, you must have known
about what this big bang theory
is all about and how and by who
does it came into existence.
There is not any perfect explanation
about what would have happened at that
instant as laws of science were not
as valid that time as they are now.
So, now as you know that
according to scientists
the earliest moment
occurs at t=1*10 (raise
to the power -43) seconds
where t refers to
the time when universe
was just been created.
So, during these earliest moments
of big bang, the universe
was believed to be so small
that classical physics
(which students usually study in
schools) doesn’t apply to it and thus
it brought out the need for getting
calculations out of quantum physics.
Though, this concept of quantum physics
actually plays with one’s knowledge and
concepts that one is already carrying in
their minds through classical physics,
but scientist believe that combination
of these two can help people in
much better way to know about how
universe actually works or originated.
Now talking about that earliest
time period, it was a time
when universe was actually
very very small, dense and hot
and that time it only covered the region of
1*10 (raise to the power -33) centimeters.
Also, it is believed that temperature
at that phase was 1*10 (raise to the
power 32) kelvin which cooled down as
soon as the universe expanded with time.
This whole process of expansion of universe
is named as inflation by cosmologists.
Moving forward, as the universe expanded,
it filled up with an equal amount
of matter and anti-matter among which
the matter was more in quality,
which later on combined with other
particles to form a matter all over.
And thus after that one second the
universe got more and more expanded
and cooled and thus made up a world
in which one can exist into.
Now, learning about that first
second you must be almost having an
idea about what all would have
happened at that time of big bang,
but there are also those 13 billion
years which took this whole universe
to create a perfect world for you and
to learn about the one, make a read.
There is a lot that happened in
that 1 second, but what next?
After around 100 seconds of all
this activity, it is believed that
the temperature of universe cooled
down to 1 billion degrees kelvin
and during which all of the subatomic
particles were in that continuous
process of combining with each other,
but electrons were still not capable
enough to combine with nuclei due to
the high temperature in universe and
thus it collided with other particles
like positrons resulting into photons.
Universe still continued
to cool and expand;
it was about after 56,000
years when universe
got cooled to 9000
degrees kelvin and thus
resulted into the density of matter
distribution to match the density of radiation.
Then, after some more of 324,000
years universe expanded
and cooled down to the temperature
of 3000 degrees kelvin
and this was the time when electrons
and protons finally got a
chance to combine with each other
and form different hydrogen atoms.
Now, this collision also allowed the
universe to get transparent and shine, i.e.
after about 380,000 years of that first
moment when universe began to form.
The radiation that is now been
examined and called as cosmic
microwave background radiation,
at that time locked away.
This is the radiation which when
studied makes scientists know that
what would have happened at the
starting of making up a universe.
Moving forward it took about
100 more million years
to universe to expand
and cool more and more,
along with which there were those gravitational
fluctuations happening continuously
which were allowing particles of
matter to cluster or combine together.
Now the gases in the universe started
getting collapsed due to the
behaviors of gravity which in turn
made it more and more dense and hot,
thus which turns out in
taking a shape of stars after
some 100 or 200 billion of
years of universe formation.
These gases converted into stars;
combined together to form
up the galaxies, though
some of them also took
the form of supernovas.
With the explosion of stars
it gave birth to the
matter which is ejected
out in the universe
and the whole process just
took their proper place
and hence at last formed
out our solar system.
It is believed that our solar system was
formed around 4.6 billion years ago.
Today as you can see the temperature of the
universe is no less or more than 2.725
degrees of kelvin which is just slight
degrees away from that absolute zero term.
Now, you know how this
whole of the universe
is formed and about
our solar system too.
Lesson to learn from Big Bang
Now, there is a lot that is
already been discussed about big
bang theory and universe and
also about the solar system.
Getting on this chapter, you are going to
know about what big bang really tell us about
this universe and what is that final lesson
that this theory can make you learn.
Big bang was initially used by cosmologists
to find out the age of universe,
but was not really accepted by
every cosmologist as according to
this theory the age span was around
more than a billions of years.
And also this discovery about expansion of
universe raised many more questions in the
mind of scientists such as will this
activity of expansion will continue forever?
Or will this take a reverse direction?
And the answer to this question
is only that it all depends
upon how much matter is
available in the universe.
You know that gravity is that
force which attracts particles of
different matter and thus make
them collapse with each other,
it is also said that the aggregate of
gravitational force which is exerted by one
body on another depends only upon the size
of those objects and space between them.
Now, if there is enough of
matter in universe then
it is said that the universe
will stop expanding
and thus which will as a result make
it to bond, this type of universe
is named as closed universe having
positive curvature by cosmologists.
But in any case if this
matter is not enough then
universe will expand,
like forever and thus it
will result into the
space which is having no
curvature or one can say
that negative curvature.
There are also many
of the scientists who
have discovered that our
universe at present
is the latest one among all
till now in this cycle
of universes that is
expanding and contracting.
Also you will be stunned to
know that universe has no
center, all according to the
concept of big bang theory
which definitely means
that all of the points
out there are just same
as like any other.
From our perception, it appears
like every other thing in the
universe is just going away in the
manner advised by the big bang.
Also, there was one theory
derived which says that earth
itself is the center of universe
as it will explain it better
about why all of the
things are going away but
later on which proved as
wrong by cosmologists.
Many of those important questions
are there, which are not talked
about by this very famous big bang
theory, which are as follows:
What happened right before this big bang?
This question is non-answerable by the
scientists as there is no calculation
about what happened when t=0 seconds and
so this is out of the reach of science.
What is there out of the universe?
Well, you know this is
also the one which is not
answerable by anyone as
one cannot really know
about what is there out of
this universe no matter
which shape this universe
is heading towards.
One just cannot know that
what is laying their
outside of the boundaries
of universe, never.
What about the shape of universe?
We don’t know.
Though, there are many of such
searches that are been carried
out about what can be the
possible shape on universe.
Some think that it is boundless
and so shapeless while
there are also some who believe
that universe is bounded.
And hence, there is no
proper solution to this.
What are the problems with Big Bang Theory?
Now as this big bang theory came into
light, there were many of those who
did everything to criticize this model
and thus raised number of questions,
actually which are worth of asking about.
Let’s have a look:
The very first criticism that
raised out of the discovery of this
theory is that it breaks up the
very first law of thermodynamics,
according to which one cannot create
or destroy the matter or energy and
big bang theory is just talking about
that universe came out of nowhere.
Answering which, the scientists
said that this theory is not
talking about the creation of
universe but the evolution.
And adding to which it is also
said that laws of science always
breaks down when one approaches
to the study of universe
and so in that case even the first law of
thermodynamics is also not to be applied.
Formation of stars and
galaxies also turned out
in the form of critic
as they said that it
violates that law of
entropy according to which
systems of change becomes
less ordered with time.
In answer to which, if one looks upon the
earlier universe being totally homogeneous
and isotropic, then universe today is
totally obeying the law of entropy.
Also there are some who
believe that these all of the
discoveries made by scientists
are just a misinterpretation.
In other words they want to say
that scientists are wrong about the
concept of redshifts or cosmic
microwave background radiation.
Some of them also claim that
there are not such celestial
bodies that were the part of
this big bang theory concept.
Big bang theory to some people
also seems to destroy the concept
that there is nothing which
can drive faster than light.
And so to answer this
criticism, people said
that at that time of
big bang there was not
any kind of such theory
been introduced and
thus it has not point
of making it an issue.
Also, it is said that space is nowhere
inside the domain of gravity and so
it can spread as fast as possible and
that too more than the speed of light.
Following these critics there
were also many of the theories
that explained this concept
of development of universe,
but all of them left behind this
big bang theory, some of them are:
Among which the very first is
steady state model, the model
which through its theory
suggests that the universe was,
is and always going to
have that same density.
This theory resolves the
obvious confirmation
that the universe is
expanding by discovering
that the universe
produces matter at a rate
proportional to the
universe's rate of extension.
Next is the Ekpyrotic
model, according to which
this universe is formed
as a result of collision,
occurred between two worlds which
are completely three dimensional
and which is somewhere hidden
in that fourth dimension.
Well, this theory is not
actually conflicting the big
bang theory as after describing
some of its concepts
it finally lands onto
the big bang theory and
thus supports the concept
described there.
Moving forwards to the big
bounce theory which according
to its discoveries suggested
that our universe
actually belongs to
the series of various
universes, which first
expands and then contracts.
Plasma cosmology is also one of
those theories which described the
universe in terms of electrodynamics
possessions of universe.
Plasma is actually described as
an ionized gas, which is the gas
having those free roaming electrons
that can conduct electricity.
Also there is one more theory
that may be very well known
by the people who have studied
about this big bang theory
and that is named as cosmic inflation
theory which gives that total
different view of describing the
universe and its evolution.
Inflation theory is the one which in its
concept brought together the ideas from
both quantum physics and particle physics
to explain the evolution of universe.
According to the concept of this
theory, it is believed that
the universe was generated in
an unbalanced energy state,
which as a result produced a fast expansion
of the universe in its first moments.
There were many of the consequences
which resulted out of this theory among
which the one was that the universe is
actually very much bigger than expected.
On the other side, another
consequence is that this theory
expects some individuality like
uniform distribution of energy
and the flat geometry
of space-time which was
never ever explained
in big bang theory.
Discovered in 1980, by a
particle physicist Alan Guth
this theory is now widely
accepted over big bang theory.
No doubt, big bang theory
provided that best
information about the
evolution of universe
but you already know that
there were also some
problems with this theory
which made it somehow
lack behind and thus
inflation theory provided
all of the information
in much better way.
So, it is now been studied as
the part of big bang theory.
Now, this is the last thing
about big bang theory
and the only thing which can be
said here is that the theory of
big bang combined with the concept
of dark matter, dark energy
and cosmic microwave background radiations
is considered as that best explanation
which one can have in relation to the
universe beginning and its evolution so far.
Although, there are still
some of the questions
that must be revolving
over there in your brain,
some of which can be sorted out with
inflation theory but there could not
be any other proper explanation of
where would this universe came from
or what happened in that first one
second or also how much years it took to
finally allow the light enter this region
and make space valuable for our living.
However, there is not any doubt
that this theory can make one’s
concept about God blurred but when
one talks about big bang theory,
then one thing which can be noticed here is
that there is still no clue about what was
that first cause which
made this happen or
which made the universe
emerge out of nowhere.
There is not any other
scientist on this earth who
can tell about what happened
before that one second,
maybe it can be that
supernatural power or who knows.
