MODULE 1 Formation of The Universe

MODULE 1
THE ORIGIN AND SYSTEMS OF EARTH

THEORIES ABOUT THE
FORMATION OF THE
UNIVERSE
BIG BANG THEORY
 The Big Bang Theory remains to be the prevailing
cosmological model for the early development of the
universe.
 According to the big bang theory, the universe was once
very small and very hot, and then it expanded over time until
it reached its peak (which may be perceived as a massive
explosion for some) around 13.7 billion years ago (considered
the age of the universe).
 The big bang model also asserts that seconds after the
explosion, the surroundings were at a high temperature of
about 10 billion degrees Fahrenheit (5.5 billion Celsius) with
aggregates of fundamental particles such as neutrons,
electrons, and protons.
 As the universe cooled in later phases, these particles either
combined with each other or decayed.
 The universe was also said to continue to expand over the
next 12 billion years until the present.
STEADY STATE
THEORY
STEADY STATE THEORY
 The Steady State Theory was first proposed by Sir James

Jeans (1877-1946) in 1920. It gained popularity after it was
revised by Fred Hoyle (1915-2001), Herman Bondi (1919-2005),
and Thomas Gold (1920-2004) in 1948 as an alternative to the
Big Bang Theory.
 This theory further claims that the universe has no beginning
or end in time, and even though it is expanding, its
appearance remains the same over time.
 However, toward the 1960’s, much evidence was
produced that would contradict the steadiness or
the unchanging state of the universe. When certain
galaxies were found only at far distances in space, it
just disprove the idea that similar bodies are created
and found everywhere.
 Thisimplies that the universe is actually evolving (and
not steady).
COSMIC INFLATION
THEORY
COSMIC INFLATION THEORY
 The most recent cosmic inflation theory was proposed by
physicists Alan Guth (1947-present) and Andrei Linde (1948-
present) in the 1980’s.
 The term inflation refers to the rapid expansion of space-time.
 According to this theory, the early universe was a rapidly
expanding bubble of pure vacuum energy. It did not have
any matter or radiation. After the expansion and cooling
arising from this inflation, the potential energy converted into
kinetic energy of matter and radiation.
1. Homogeneity of object in space
 During the expansion period, objects that used to be in

contact got far away from one another. Their composition,
however, remained almost intact.
2. Appearance of flatness or smoothness
 Thecontinuous expansion “dilutes” or gradually loses

the curvature of objects.
3. The formation of stars and star
systems in later years
 The theory asserts that during expansion, small density

fluctuations happen. This causes gravity to attract gas into
masses, giving birth to stars and eventually galaxies. This also
explains why the universe would always look full of planetary
objects instead of appearing completely empty.
FORMATION OF
STAR SYSTEMS
NEBULAR
HYPOTHESIS
Nebular Hypothesis
 The nebular hypothesis was develop by Immanuel Kant (1724-
1804) and Pierre-Simon Laplace (1749-1827) in the 18th
century. It was the model used to explain the formation and
evolution of the solar system.
 It presuppose that around 4.6 billion years ago, a star system
was formed from a rotating gas cloud or nebula of extremely
hot gas. When the gas cooled, the nebula began to shrink,
and as it became smaller, it rotated faster, forming a disk like
shape.
 The angular momentum from the nebula’s rotation and the
gravitational force from the mass of the nebula formed the
rings of gas outside. As the nebula continued to shrink, these
rings condensed into various densities of planets and their
satellites. The remaining part of the nebula, which had the
most mass, formed the sun.
PLANETESIMAL AND
TIDAL THEORIES
PLANETESIMAL and TIDAL THEORIES
 The planetesimal and tidal theories were developed by

Thomas Chamberlin (1843-1928)and Forest Moulton (1872-
1952) during the early 20th century, and James Jeans (1877-
1946) and Harold Jeffreys (1891-1989) in 1918, respectively.
 In both theories, a star supposedly passed close to the sun.
the gravitational pull of the passing star raised tides found on
the surface of the sun. some of this erupted matter was
detached and plunged into elliptical orbits around the sun.
Some of the smaller masses quickly cooled to become solid
bodies called planetesimals.
 Others grew in size because of collision with passing objects in
space, eventually forming larger clumps and gathering more and
more matter. These theories are also backed up by old meteorites
found on Earth, chemically dating back 4.56 billion years---the
time approximated to be the formation of the solar system.
 In both theories, the formation of the planets was explained. At
present there are four inner planets (Mercury, Venus, Earth and
Mars) that are known to be much smaller compared to the other
four outer planets (Jupiter, Saturn, Uranus, Neptune). Even the
physical and chemical properties of these two groups of planets
differ immensely.
 The four outer planets are called gas planets because the are made
up of only primary material (helium and hydrogen) that make up the
sun. these giants gas planets are believed to have remained gaseous
in nature because of their great distance from the sun. the lower
temperature, known to be observed beyond the frost line, allowed
the condensation of gas, forming a less dense huge planet.
 On the other hand, the four inner planets are called terrestrial or
telluric planets because they have solid surfaces and are mostly of
silicate rocks and metals. Earth is one of the inner planets, and as
such, it share some common characteristics with the other terrestrial
planets.

MODULE 1 Formation of The Universe

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MODULE 1 Formation of The Universe

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MODULE 1

THE ORIGIN AND SYSTEMS OF EARTH

 The Steady State Theory was first proposed by Sir James

 During the expansion period, objects that used to be in

 Thecontinuous expansion “dilutes” or gradually loses

 The theory asserts that during expansion, small density

 The planetesimal and tidal theories were developed by

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