The Origin of the Earth, its Oceans and Life in the Oceans
Pertemuan ke-2 (Asal-usul bumi, laut dan kehidupan di laut)
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The Universe Galaxies Stars Planets
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Cosmology Is the study of the universes origin, evolution and
current nature. Observations are made by measuring electromagnetic
radiation, observing the movement of stars, and by determining the
mass and density of the universe. Theories are developed by these
observations.
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Doppler Effect Is the changing length of light or sound waves
as an object moves closer or further away from an observer. With
light, as an object moves closer light waves are compressed and
become blue- shifted, as an object moves away the light waves
become stretched and become red- shifted.
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BLUE RED
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The Origin of the Universe The Big Bang Theory is the
prevailing scientific explanation of the origin of the universe.
This theory proposes that at one time all matter was concentrated
into a single, extremely dense body. Then about 15 billion years
ago, a tremendous explosion sent this matter hurling outward into
space. 1 billion=10 9 [email protected]
Inflationary Model Universe began a fluctuation in a vacuum,
expanded explosively fast in fractions of a second, then went into
ordinary expansion, H = expansion constant which is used to
estimate the age of the universe.
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THE COMPETITORS FOR THE THEORY ON ORIGIN OF THE UNIVERSE The
Bubble Universe / Andre Linde's Self Creating Universe The
Inflationary Theory (1981, Alan Guth ) The Proto-universe (white
hole theory) The Steady State Theory (late 1940s ) The Oscillating
Universe Theory (1960s -70s ) [email protected]
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Steady State Theory Universe looks the same on a large scale to
all observers and has always looked that way. In order to maintain
the same density matter is created as it expands.
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Big Bang Favored Theory Reason why: Steady state cannot
explain- Cosmic Background Radiation (CBR) this is the persistent
background noise a radio antennae picks up. Believed to be the
remnants of the Big Bang explosion. It comes from all directions in
space and has a temperature that relates to an object of 273.5K
(-270 0 C).
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Evidences for the Big Bang Galaxies are moving away from us at
speeds proportional to their distance. This is called "Hubble's
Law," named after Edwin Hubble (1889-1953) who discovered this
phenomenon in 1929 The abundance of the "light elements" Hydrogen
and Helium found in the observable universe are thought to support
the Big Bang model of origins Cosmic Background Radiation predicted
by Cosmologist George Gamov in 1948 and discovered by Arno Penzias
& Robert Wilson of Bell Labs in 1965.
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Hubbles Law Hubble observed that more distant galaxies were
moving away at a faster rate (larger red shifts) than closer
galaxies. The relationship between distance and speed is known as
Hubbles Law, galaxies are not expanding, the space between them is.
V= Hd v= speed (km/sec) at which galaxy is moving away, H = Hubbles
constant measured in km/sec/mpc (speed/distance), and d= distance
to the galaxy measure in megaparsecs (Mpc) He concluded that the
universe is expanding. Given the speed of a galaxy and a graph of
the Hubble constant the distance of very remote galaxies can be
determined.
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Formation of the Elements Within minutes, the universe expanded
to an enormous size and cooled enough to allow protons and neutrons
to fuse together to form atomic nuclei, a process known as
nucleosynthesis. Within just one days time, nucleosynthesis
produced nearly all of the hydrogen and helium nuclei in existence
today. Hydrogen and helium are the lightest and most abundant
elements in the universe. Heavier elements account for only about
0.1% of all the elements in the universe.
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Expanding Universe The early universe continued to expand like
a cloud of hot gases. Over the next billion years, gravity
compressed pockets of these gases into the first stars and
galaxies. [email protected]
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Galaxies and Stars A star is a massive sphere of incandescent
gases (gas pijar). A galaxy is a rotating collection of stars,
dust, gas, and other interstellar debris held together by
gravitational attraction. The universe may contain as many as 50
billion galaxies, each with nearly 50 billion stars
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Galaxies
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Galaxies are groups of stars that have a galactic center,
nucleus, around which stars move. Galaxies have different shapes
and sizes. Galaxies are classified according to their shape.
Clusters of galaxies exist in the universe.
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Galaxy Classification Spiral Galaxies 1) Normal Spirals arms
extend directly from nucleus 2) Barred Spiral elongated central
region extends from nucleus with arms out from either side of bar.
Andromeda NGC1300
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Galaxy Classification Elliptical Galaxies are not flattened and
there are no spiral arms. Irregular Galaxies all other galaxies
that do not fit into spiral or elliptical.
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Galactic Mass Galaxies average range in size from as small as 1
million suns to as many as 100 billion suns. Giant elliptical
galaxies can be as massive as 100 trillion suns.
A light year is a unit of measure used by astronomers to
describe distance within the universe and is equal to the distance
traveled by light at speed of 300,000 km/s during a period of one
year, almost 10 trilliun (9.8 x 10 12 km)
Democritus (460 370 B.C.) Greek astronomer who first discovered
the Milky Way and claimed it was made up of billions of stars far
away. (not confirmed until much later).
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Edwin Hubble (1889 1953) Confirmed the existence of galaxies in
1924 when he measured the distance of Cepheid variable stars in the
Andromeda constellation to be too far away to be in our
galaxy.
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Formation of the Milky Way Galaxy Most likely started as an
elliptical galaxy making up the halo and nucleus present today.
Eventually collapsed under its own gravity and began to rotate
forming a disc-like shape. Elliptical
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Dimensions of the Milky Way Galaxy It is a spiral shaped
galaxy, possibly a barred spiral galaxy. About 100,000 light years
across. 946,073,047,258,080,000 km ~ 946 quadrillion km
587,862,537,318,361,000 mi. ~ 588 quadrillion mi. About 1,000 light
years thick. Consists of 200 to 400 billion stars Consists of a
massive galactic center that bulges out with spiral arms extending
outward from center.
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Production of Heavier Elements Most stars burn hydrogen to
produce helium and energy. Four hydrogen atoms fuse to form a
helium atom. In this process a small amount of matter is converted
into a vast amount of energy. After a star has burned most of its
hydrogen, it collapses. If it is large enough, the collapsed star
then burns helium, forming the heavier elements of carbon and
oxygen. Red giants (massive stars) undergo this cycle of fuel
burning/collapse several times, forming silicon, magnesium, and
heavier elements. [email protected]
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Supernovas When all of a large stars fuel is consumed, it
undergoes a final sudden collapse, then explodes violently in a
supernova, propelling much of its matter into space. The force of
the supernova produces neutrons that collide with other atoms from
the exploding star to form the heavier elements, which are thrust
into space to become part of the interstellar dust.
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Axis of rotation Approx. 1 light year Axis of rotation Rotation
retards collapse in this direction Slowly spinning interstellar
cloud Gravity makes cloud shrink. As it shrinks it spins caster and
flattens into a disk with central bulge. Approx. 100 AU Axis of
rotation
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Origin of the Solar System The sun and the planets of the solar
system have a common origin, all coalescing from the solar nebula,
a rotating cloud of interstellar dust and gas enriched with heavy
elements released by supernovas. The rotation of the nebula caused
it to flatten, and gravity contracted the material near the center
into a protosun. Material farther from the center accumulated into
the planets. [email protected]
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The Solar Wind Once the internal temperature of the protosun
increased to the point where hydrogen atoms fused into helium, it
became the sun. The intense solar wind produced when the sun lit
swept most of the gaseous elements out of the inner solar system.
The elements that remained to form the Earth were oxygen (mostly
bound to metals), silicon, iron, aluminum, calcium, magnesium,
sodium, and potassium, the elements that constitute most of the
rocks found on the Earth today. [email protected]
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The Evolution of Earth Our planet accumulated from the
interstellar material by accretion. Centimeter-sized particles and
gases condensed into kilometer-scale planetesimals (small
proto-planets). The planetesimals were drawn together by gravity
and fused into a planet. [email protected]
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Differentiation of the Earths Interior The earths original
composition was uniform throughout. Late in the accretion stage,
frequent collisions with meteors and other debris from outer space
caused the surface of the planet to heat up. Additional heating
from the decay of radioactive elements within the earth caused the
whole planet to melt! Gravity pulled the heavy iron inward to form
the mantle and core. Lighter materials of silicon, magnesium,
aluminum, and oxygen-bonded compounds migrated upward. About 4.6
billion years ago, the first hard surfaces crystallized into the
crust. [email protected]
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The Geologic Time Scale Scientists have detailed the Earths
history dating back 4.6 billion years in the Geologic Time Scale.
This scale is divided into a hierarchical set of increasingly
smaller units of time, such as eons, eras, periods, epochs, and
ages. [email protected]
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The Early Atmosphere The atmosphere began to form about 4.4
billion years ago during the Precambrian period. Frequent volcanic
eruptions and earthquakes allowed carbon dioxide, nitrogen, and
other gases trapped inside the planet to escape (outgas) and form
the atmosphere. The degassing of comets plunging to the earths
surface also released quantities of ammonia, methane, and water
vapor into the atmosphere. [email protected]
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Composition of the Atmosphere The levels of carbon dioxide were
as much as 1,000 times present levels. Because oxygen rapidly
bonded to metals in the crust to form oxides, like the rusting of
iron, there was no oxygen present in the early atmosphere. Water
vapor was so abundant in the primordial atmosphere from out gassing
that the atmospheric pressure was several times greater than today.
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Suns energy stripped away 1 st atmosphere 2 nd atmosphere
formed from volcanic out gassing Primitive atmosphere: CO 2, water
vapor, lesser amts of CO, N 2, H 2, HCl, and traces of NH 3 and CH
4 (3.5 bya) [email protected]
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The Blue Planet After several million years, the atmosphere
cooled sufficiently to allow the water vapor to condense into thick
clouds which cloaked the entire planet. Rain began to fall from the
sky, cooling the surface. Rainwater collected in craters and
basins, where it evaporated, cooled and fell again. A period of
heavy rains deluged the planet for some 10 million years. When the
rains ceased and the skies cleared, the Earth emerged as a blue
planet carpeted by an ocean almost two miles deep, sprinkled with
volcanic islands. [email protected]
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Formation of Earths Oceans: Rain Condensation Off gassing of
water vapor from volcano [email protected]
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The Continents Originally, there was little, if any,
continental land mass. Underlying the sea is a layer of oceanic
crust about 8 km thick, primarily composed of basalt, a dense,
iron-rich rock of volcanic origin. Continental crust is thicker
(2070 km), and typically composed of lighter, granitic rock
distilled from the repeated recycling of mantle material and
oceanic crust (a process discussed in the next lesson). The first
continental crust probably came into existence at a few isolated
island arcs and has accumulated over time into the large land
masses we know today. Explanations describing the origin and
evolution of the continents are still highly speculative.
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The First Supercontinent By the end of the Precambrian period,
approximately 700 million years ago, all land masses had gathered
into the single supercontinent Rodinia, surrounded by the
Panthalassic Ocean. [email protected]
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The Moon Ocean tides are a primarily a result of an interplay
of forces between the Earth and the Moon. The leading theory of the
Moons origin is the giant impact hypothesis. At the time Earth
formed, other smaller planetary bodies were also growing nearby.
One of these bodies, about one-third to one- half the size of
Earth, struck the Earth late in its growth process. Debris from
that collision went into orbit around the Earth and aggregated into
the moon. [email protected]
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The Moon and the Earth The Moon, the largest in the solar
system relative to its mother planet, may have stabilized the tilt
of the planets rotational axis that produces the seasons. Without
the Moon, Earth might experience the extreme and hostile
fluctuations in weather and climate observed on Mars.
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Life began~ 3.5 bya Organic molecules (C H O N P S) swimming in
shallow seas Stage 1: Abiotic synthesis of organic molecules such
as proteins, amino acids and nucleotides Origin of life
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Stage 2: joining of small molecules (monomers) into large
molecules [email protected]
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Stage 3: origin of self-replicating molecules that eventually
made inheritance possible [email protected]
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Stage 4: packaging these molecules into pre- cells, droplets of
molecules with membranes that maintained an internal chemistry
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Thomas Huxley- Search for origin of life Bathybias heckalii-
primordial ooze Wyville Thompson: HMS Challenger (1872- 1876) found
it was actually diatomacous ooze reacting with seawater and ethyl
alcohol Also, disproved Forbes Azoic Theory (1868-1870)
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Miller & Urey (1953)- mixed water vapor, NH 3, CH 4, H 2 +
electric spark amino acids and other organic compounds electrodes
spark CH 4 NH 3 H 2 water vapor condenser boiling water water
containing organic compounds
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Produced: 20 amino acids Several sugars Lipids Purine and
pyrimidine bases (found in DNA, RNA & ATP)
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chemosynthetic bacteria (extremophiles) Chemosynthesis: 0 2 +
4H 2 S + C02 CH 2 0 + 4S +3H 2 0 Stromatolites (bacteria &
cyanobacteria) Oldest fossils found in western Australia and
southern Africa ~ 3.5 bya Photosynthesis: 6H 2 O + 6CO 2 +
nutrients + light energy C 6 H 12 O 6 + 6O 2
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Stromatolites from Sharks Bay Australia mostly cyano
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PANSPERMIA THEORY Organic compounds arrived from outer space It
states that hydrocarbons and other organic molecules (molecules
that organisms contain or that might lead to the genesis of life)
have been found in meteorites It means that at least prebiotic
chemistry that leads to the primordial soup might be going on
there. [email protected]
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Evidences in support of this theory In 1969, a meteorite landed
in Australia that was 12% water and contained traces of 92 amino
acids. Inference- It points to not only the presence of organic
compounds in outer space, but also the capacity of such compounds
to reach earth. Fred Hoyle and Chandra Wickramasinghe have argued
persistently since the 1970s that complex organic substances, and
perhaps even primitive organisms, might have evolved on the surface
of comic dust grains in space and then been transported to the
Earth's surface by comets and meteorites.
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Where did life begin??? There is an ongoing debate regarding
the most probable site of life's origins. The prevailing paradigm -
life began near the ocean's surface, bathed in sunlight. Current
Research - life arose near deep hydrothermal vents which is still
under investigation. "Scientists have long suspected that life on
Earth originated in the ocean and strong evidence now suggests that
the earliest life on our planet occurred in the depths of the ocean
in the absence of heat and light." -- Pulse of the Planet, American
Museum of Natural History [email protected]
Deep-sea Vents Their discovery in late 1970s stretched our
concept of the origin of life on earth. Can life exist and that too
thousands of meters beneath the surface of sea in absence of
sunlight? It raised the possibility that earlier vents supplied the
energy and chemical precursors for origin of protobionts.
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Exploring the deep ocean floor View of the first high-
temperature vent (380C) ever seen by scientists during a dive of
the deep-sea submersible Alvin in 1979. Such geothermal vents are
called smokers. This photograph shows a black smoker, but smokers
can also be white, grey, or clear depending on the material being
ejected. Photograph by Dudley Foster from RISE expedition
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Vent Community A vent community in its prime : Pale pink
eelpout fish and white brachyuran crabs swim and scuttle among
blood-red tube worms large and small. Scientists are still trying
to figure out how the offspring of such organisms disperse over
long stretches of inhospitable seafloor to colonize widely
separated vent systems. [email protected]
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Giant Clams The size of deep-sea giant clams is evident from
the hands of a scientist holding them. (Photograph by William R.
Normark, USGS.) [email protected]
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Giant Tube Worms: RIFTIA On the bottom of the ocean around
deep-sea hydrothermal vents, there is a profusion of life that
thrives on the hydrogen sulfide (H 2 S) gas released from the
vents.and live inside hard, shell-like protective tubes that attach
to the rocks. Giant tubeworms that live around hydrothermal vents
on the sea floor. These creatures are about the size of your hand
in shallower waters, but in the ocean's deep they have been found
as big as eight feet long! [email protected]
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How they live. These creatures lack mouths, anuses, intestines
and stomachs, and scientists were at a loss to explain how these
were getting nutrients to survive and grow. Their insides are lined
with bacteria that oxidize the H 2 S, turning it into usable
nutrients for the worms. The bacteria, in turn, benefit from the
relationship because the worms deliver blood containing hemoglobin
which helps the bacteria to break down the sulfides. They live in a
symbiotic relationship with a bacteria that may hold clues as to
how life on earth began billions of years ago.
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BIOCHEMISTRY AT THE VENTS H 2 S Oxidation by bacteria Energy
released helps in fixing CO 2 into small organic molecules So this
cycle... is the same metabolic pathway that is utilized by plants
in photosynthesis... takes inorganic carbon dioxide and fixes it
into organic compounds that are then food. But, the difference
here, the critical difference, is that rather than using sunlight,
these animals and bacteria are completely independent of sunlight.
They utilize chemical energy to power that reaction. So, ever
imagined a life out of toxic Hydrogen Sulphide?! Released from
vents [email protected]
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Chemical of Life - Ammonia, Produced at Vents Hydrothermal
vents were the most likely site for NH 3 production where inorganic
sulphides acted as catalyst. N 2 +NO 2 +N0 3 Presumed to be present
in ancient sea NH 3 FeS, 500 o C 89% yield, 15 min FeO 46% yield 15
min Powdered Basalt. 20% yield Stable upto 800 o C
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RESULTS Since NH 3 cannot survive at temperature above 800 o C
indicates that nitrogen would have been present only as N 2 during
early phase of earths development. Life can exist on thermal and
chemical energy as opposed to just sunlight as had been thought in
the past. And so what was realized is that photosynthesis was not
the only way to support life. [email protected]
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What has been discussed so far In 1920s, Oparin and Haldane
revived the doctrine of spontaneous generation in a more
sophisticated form. In 1953, American chemists Stanley Miller and
Urey showed that some amino acids can be chemically produced from
NH 3 and CH 4 in 1970s, Fred Hoyle and Chandra Wickramasinghe
rekindled interest in Panspermia. They found evidences, traces of
life, in the intervening dust. In 1980s the hunt for the most
probable site of lifes origin began and then we came to deep sea
hydrothermal vents.This discovery stretched our concept of the
origin of life on earth. [email protected]
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Scientists are still debating over which came first, the
nucleic acids or the proteins. Recent experiments on the revised
atmospheric conditions have been successful in producing the usual
monomers and a few that were not formed in the Miller- Urey
experiment. The mass action law suggests that polymerization is not
likely to have occurred in the sea, but more likely to have
occurred in heated and highly concentrated pools of monomers.
Treating amino acids in this manner, Sydney Fox produced polymers
that aggregated into what he called proteinoids.
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