Academic important learning materials.

1. EARTH AND LIFE SCIENCE NOTES
LESSON 1: THEORIES ON THE ORIGIN OF THE UNIVERSE
In an effort to make sense of the universe, humans used religions, traditions,
philosophy, and science to describe its origin and structure. There are stories and beliefs
passed on from one generation to another, and there are hypothesis and theories that
were continuously tested and challenged through the scientific method.
 RELIGIOUS BELIEFS
1. Genesis – the narrative of Genesis, one of the books of the Hebrew Bible and
Christian old testaments, described how God separated light from darkness,
created the sky, land, sea, moon, stars, and every living creature in a span of
six days.
2. Rigveda – this Hindu text describes the universe as an oscillating universe in
which a “cosmic egg” or Brahmanda, containing the whole universe-
including the sun, moon, planets, and space, expands out of a single
concentrated point called Bindu, and will eventually collapse again.
3. From the 5th century to 3rd century BCE, the Greek philosophers would present
their own description of the universe.
3.1ANAXAGORAS – believed in a primordial universe and explained that the
original state of the cosmos was primordial mixture of all its ingredients
which existed were present in infinitesimally small fragments of themselves.
4. Greek philosophers LEUCIPPUS and DEMOCRITUS believed in an atomic
universe. They held that the universe was composed of very small, indivisible,
and indestructible atoms. All of reality an all the objects in the universe are
composed of different arrangements of these eternal atoms and an infinite void
in which the atoms form different combinations and shapes.
5. STOIC Philosophers – also believed that universe is like a giant living body,
with the sun and the stars as the most important parts to which everything else
was interconnected.
6. Aristotle and Ptolemy – proposed the geocentric universe where earth stayed
motionless in the heavens, and everything is revolving around it.
7. Nicolaus Copernicus – proposed the theory of heliocentrism, which
demonstrated that the motions of the celestial objects can be explained without
putting Earth in the center of the universe. His theory contradicts with the
geocentric universe of Aristotle and Ptolemy.
8. Isaac Newton – described the universe as a static, steady-state, infinite
universe. In this description of the universe, matter on the large scale is
uniformly distributed, and the universe is gravitationally balanced but
essentially unstable.
9. Rene Descartes – outlined a Cartesian vortex model of the universe with many
of the characteristics of Newton’s static, infinite universe. According to him, the
vacuum of space was not empty at all but was filled with matter that swirled
around in large and small vortices.
10.Albert Einstein – was no different from Newton’s in that it was a static,
dynamically-stable universe, which was neither expanding nor contracting. He
added a cosmological constant to his general theory of relativity equations to
counteract the dynamic effects of gravity, which would have caused the
universe to collapse.

2.  MODERN THEORIES
1. Steady State - The now discredited steady state model of the universe was
proposed in 1948 by Hermann Bondi, Thomas Gould and by Fred Hoyle. It
maintains that new matter is created as the universe expands thereby
maintaining its density. Its predictions led to tests and its eventual rejection with
the discovery of the cosmic microwave background.
2. Big bang Theory - The Big Bang theory is an explanation of the early
development of the Universe. According to this theory the Universe expanded
from an extremely small, extremely hot, and extremely dense state. Since then,
it has expanded and become less dense and cooler. The Big Bang is the best
model used by astronomers to explain the creation of matter, space, and time
13.7 billion years ago.
3. Oscillating Universe – was Albert Einstein favored model after rejecting his
own original model. The oscillating universe followed the general theory of
relativity equations of the universe positive curvature. This curvature results in
the expansion of the universe for a time, and then to its contraction due to the
pull of its gravity in perpetual cycle of big bang and big crunch.
4. Inflationary Universe – Alan Guth proposed a model of the universe based on
the big bang theory. He incorporated a short early period of exponential cosmic
inflation to solve the uncertainties of the standard big bang model, such as
horizon and flatness problems. This became known as the inflationary model.
5. Multiverse – Andrei Linde developed the concept of inflationary universe from
his chaotic inflation theory in 1983. This theory sees the universe as just one
of many “bubbles” that grew as part of a multiverse.
LESSON 2: THE ORIGIN OF THE SOLAR SYSTEM
The solar system is in the Milky Way galaxy, a huge disc- and spiral-shaped
aggregation of about at least 100 billion stars and other bodies. Its spiral arms rotate
around a globular cluster or bulge of many, many stars, at the center of which lies a
supermassive blackhole. Our Sun lies near a small, partial arm called the Orion Arm, or
Orion Spur, located between the Sagittarius and Perseus arms.
1. Encounter Hypothesis - One of the earliest theories for the formation of the
planets was called the encounter hypothesis. In this scenario, a rogue star passes
close to the Sun about 5 billion years ago. Material, in the form of hot gas, is tidally
stripped from the Sun and the rogue star.

3. 2. Nebular Hypothesis - In the 1700s Emanuel Swedenborg, Immanuel Kant, and
Pierre-Simon Laplace independently thought of a rotating gaseous cloud that cools
and contracts in the middle to form the sun and the rest into a disc that become
the planets. It states that the entire solar system starts as a large cloud of gas that
contracted due to self-gravity. This nebular theory failed to account for the
distribution of angular momentum in the solar system.
3. PROTOPLANET HYPOTHESIS
o About 4.6 billion years ago, in the Orion arm of the Milky Way galaxy, a
slowly rotating gas and dust cloud dominated by hydrogen and helium
started to contract due to gravity.
o As most of the mass moves to the center to eventually become a proto-Sun,
the remaining materials form a disc that will eventually become the planets
and momentum is transferred outwards.
o Due to collisions, fragments of dust and solid matter begin sticking to each
other to form larger and larger bodies from meter to kilometer in size. These
proto planets are accretions of frozen water, ammonia, methane, silicon,
aluminum, iron, and other metals in rock and mineral grains enveloped in
hydrogen and helium. High-speed collisions with large objects destroy
much of the mantle of Mercury, putting Venus in retrograde rotation.
o Collision of the Earth with large objects produces the moon. This is
supported by the composition of the moon very similar to the Earth's Mantle
o When the proto-Sun is established as a star, its solar wind blasts hydrogen,
helium, and volatiles from the inner planets to beyond Mars to form the gas
giants leaving behind a system we know today.

4. LESSON 3: LIFE ON EARTH
Earth as a terrestrial planet is the only one that can support life among the planets
in our solar system. Some important requirements that are necessary in supporting life
on Earth include the presence of the following:
1. Liquid water – Life would not have begun without water. The presence of water
allowed the first photosynthetic organisms to live. Organisms such as
cyanobacteria used sunlight, carbon dioxide, and water to produce biomass
and OXYGEN, an essential component of the atmosphere. Earth also located
in the HABITABLE ZONE where the distance from our sun is enough to hold
the water in its liquid form.
2. Heat source – The heat that drives the different systems necessary to support
life on Earth comes from two sources: (1) internal heating of Earth and (2)
External heating from the sun.
3. Atmosphere - An atmosphere is a layer of gas or layers of gases that enclose
a planet and is held in place by the gravity of the planetary body.
 EARTH’S SUBSYSTEM
- Earth science looks at the entire planet as a system of interacting parts of
subsystems. Earth subsystems are interconnected to each other.
- Earth is considered a CLOSED SYSTEM. The amount of matter within the
closed system is fixed. This can be illustrated by discussing the volume of
mineral resources a system has. The resources used can never be
regenerated, and the waste produced cannot really be disposed. Once used
up, the mineral resources are transformed into something else, maintaining the
amount of matter within this closed system.
- Although Earth is considered a closed system, THE SUBSYSTEM OF THE
EARTH ARE OPEN SYSTEM which means the matter and energy can freely
transfer between them, thus a disturbance in one system affects the others.
 THE FOUR SUBSYSTEMS OF EARTH
1. Geosphere – refers to the solid Earth. It is composed of naturally occurring
solid aggregate of minerals, organic material, or natural glass called ROCKS,
and loose particles of rocks that blanket the surface of the Earth called
REGOLITHS. It also includes landforms such as mountains and hills.
2. Hydrosphere – is the totality of Earth’s water, including permanent frozen parts
called CRYOSPHERE. Earth is the only planet in the solar system that contains
water in all its three phases (SOLID, LIQUID, GAS).
3. Atmosphere – is the mixture of gases (nitrogen, oxygen, argon, carbon
dioxide, and water vapor) that surrounds planet. It helps protect life on Earth by
shielding the incoming UV radiation.
4. Biosphere – includes all life forms and even organic matter that has not yet
decomposed. Biosphere consists of living organisms both Microorganisms
(small organisms) AND Macroorganisms (large organisms).
These four subsystems are closely link through biogeochemical cycles, these
biogeochemical cycles are pathways by which chemical substances move through both
biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) components of
Earth. It allows the circulation of important chemical nutrients that form and support life-
carbon, oxygen, nitrogen, phosphorus, calcium, and water-through the biological and
physical world.