Universe
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is large unimaginable expense of gas, stars,
dusts, clouds, and consists of planets and
galaxy.
at least 13.7 billion of years old and the
Earth/ Solar system at 4.5-4.6 billion of
years.
Diameter of the universe is of least 91
billion light-years (1 light year = 9.4607 x
1012 km)
Universe as we currently now comprise all
space and time and all matter and energy in it.
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4.6% baryonic matter
24% cold dark matter
71.4% dark energy
Three most abundant elements
Star
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building block of galaxies born out of dust
galaxies clouds of gas and dust in galaxies
most stars such as the sun belong to the socalled “main sequence stars”
in the core of such stars, hydrogen atoms
are fused through thermonuclear reactions
to make helium atoms
1929, Edwin Powell Hubble announced his
significant discovery the "redshift" hence as
evidence for an expanding universe, just as
predicted by Einstein's Theory of General
Relativity
The Big Bang Theory
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stated that the universe began in a small
hot dense state, the rapid expansion about
13.7 billion years ago.
this means that there no was no where,
when or what space around the singularity.
the temperature in the early universe were
so high that fusion reactions could take
place.
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all of it then began to rapidly expand in a
process inflation. Space itself expanded
faster than the speed of light.
in this still hot and dense mass of the
universe, pairs of matter and antimatter
(quarks and antiquarks) were formed from
energy, but these pairs cancelled each other
back into energy (annihilation).
the universe cooled down as it expanded.
the lightest elements (hydrogen, lithium,
deuterium, helium) were produced in the
Big Bang.
resulted in the formation of light elements:
hydrogen, deuterium, helium (two
isotopes), lithium and trace amount of
beryllium.
Experimental Evidence supports
the Big Bang in Three Major Areas.
Cosmological Redshift - galaxies today have
redshift in their spectrum lines
Cosmic Microwave Background - microwave
radiation that fills all space and is thought to
represent the redshifted glow from Big Bang
There is a H to He mass ratio of 3 is to 1 in the
stars and interstellar material as predicted by
the Big Bang model
The theory rests on two ideas:
Steady state / Infinite Universe Theory
↳ Matter is constantly created as the universe
expands
Big Bang Cosmology
↳ Matter dilutes as the universe expands
Pulsating Universe Theory
Solar System
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is the gravitationally bound system
comprising the sun and the objects that
orbit around it, either directly or indirectly
in constant motion, with the planets and
their moons, comets, asteroids and other
space objects, revolving around the Sun.
Evidence that supports Big Bang
- the detection of cosmic microwave
background or heat leftover from the Big Bang
Proponents of Big Bang Theory.
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Georges Henri Joseph Edouard Lemaître
was the first proponent of the theory. He
suggested the idea of the expanding
universe.
Edwin Powell Hubble established the
Hubble's Law and provided evidence that
the universe was not static but expanding.
Arno Penzias and Robert Wilson discovered
the cosmic microwave background.
Drawbacks of the Big Bang Theory
 It fails to explain how the universe was
created.
 It just explains how the universe evolves
and not where it originated.
 It also Fails to explain how the galaxies
formed.
The Universe according to the
Steady State Theory
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has no beginning and has no end
has always been here and will always be
present
always look the same in any time and space
created new matter as it continuously
expands
Proponent of the Steady State
Theory
Hermann Bondi, Thomas Gold, and Fred Hoyle
proposed the steady state theory in 1948
Drawback of the Steady State
Theory
 It is not parallel with the law of
conservation of energy and matter
 The discovery of cosmic microwave
background significantly supported the
explanation given by the Big Bang Theory
and led many scientists to reject the steady
state theory in 1965
Oscillating Universe Theory
- also known as the pulsating universe theory,
proposed that the universe is expanding and
will contract once all the energy after the Big
Bang has been used up.
- it will expand again.
Proponent of the Oscillating
Universe Theory
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Richard Tolman - caltech professor
he called the birth of another universe the
“big bounce”
Nebular Theory
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the solar system originated from a nebula.
it is widely accepted view about the
formation of the solar system some 4.5
billion years ago
a nebula is defined by NASA as giant cloud
of gas and dust in space.
this interstellar cloud of dust contains
hydrogen helium, and other ionized gases.
Major Steps in the Formation of the
Solar System
The formation of the solar system from a
nebula
1. Cloud collapse
2. Formation of protoplanetary disks and
3. Growth of planets
Proponent of the Nebular Theory
o
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Drawbacks of the Nebular theory
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Step 1: Cloud Collapse
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Hypothetically, a shockwave from a
supernova or a passing star may cause a
cloud collapse
The collapse occurs at the center of the
cloud due to gravity when gas pressure
becomes insufficient to support the
mass of the cloud
The collapsed cloud of interstellar gas
and dust results to a smaller radius that
spins faster
Step 2: Formation of Protoplanetary Disks
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Metals and silicates could exist near the
sun because these compounds hare
higher boiling point
As a result, terrestrial planets were
eventually form containing high
concentration of these compounds.
The terrestrial planets could not grow in
huge diameter because of the limited
reserve of metallic elements in the solar
nebula.
Step 3: Growth of Planets
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Dust and grains surround the sun
eventually formed clumps These clumps
then accreted worming planetesimals
Planetesimal is a small celestial body
that once collide together
It tends to fuse to Form the planets of
the solar system.
Emmanuel Swedenborg (1408-1772)
Immanuel Kant (1729-1804)
Pierre-Simon Laplace (1799-1821)
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Particles surrounding Saturn repel each
other which is contrary to the assumption
that dust particles will be attached to each
other forming planet.
It does not follow the law of angular
momentum because of the nebular theory
is correct then the sun should be spinning at
a higher rate than others.
It did not consider Uranus and Venus which
rotates in a clockwise direction while the
other planets rotate in a counterclockwise
direction
The Encounter Theory
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The Encounter theory proposes that the
planets were formed from the material
ejected from the sun during an encounter
with another celestial object, such of
another star.
Two Forms: Planetesimal and Tidal Theories
Planetesimal Theory
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It proposes that a passing star termed as
intruding star nearly collided with the
protosun
The massive gravitational pull of the
intruding causes the protosun to star eject
filament of materials, which then
condensed into planetesimal.
This theory describes how Earth started
from a solid mass smaller than its present
size
Proponent of the Planetesimal
Theory
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Thomas Chrowder Chamberlin - proposed
that accretion of minute solid particles
created planets and their moons rather
than by gaseous or liquid material
condensation.
Forest Ray Moulton