The Origin of the Earth, its Oceans and Life in the Oceans Pertemuan ke-2 (Asal-usul bumi, laut dan...

The Origin of the Earth, its Oceans and Life in the Oceans Pertemuan ke-2 (Asal-usul bumi, laut dan kehidupan di laut) [email protected]

The Universe Galaxies Stars Planets

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.

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.

BLUE RED

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]

Timeline of the Big Bang [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.

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]

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.

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).

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. [email protected]

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.

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.

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]

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 [email protected]

Galaxies

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.

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

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.

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.

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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)

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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).

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.

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

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.

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]

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. [email protected]

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

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]

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]

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]

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]

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]

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]

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. [email protected]

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]

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]

Formation of Earths Oceans: Rain Condensation Off gassing of water vapor from volcano [email protected]

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. [email protected]

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]

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]

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. [email protected]

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 [email protected]

Stage 2: joining of small molecules (monomers) into large molecules [email protected]

Stage 3: origin of self-replicating molecules that eventually made inheritance possible [email protected]

Stage 4: packaging these molecules into pre- cells, droplets of molecules with membranes that maintained an internal chemistry [email protected]

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)

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

Produced: 20 amino acids Several sugars Lipids Purine and pyrimidine bases (found in DNA, RNA & ATP) [email protected]

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

Stromatolites from Sharks Bay Australia mostly cyano [email protected]

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]

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. [email protected]

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]

Photograph from National Geographic magazine [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. [email protected]

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 [email protected]

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]

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]

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]

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. [email protected]

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]

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 [email protected]

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]

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]

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. [email protected]

The Origin of the Earth, its Oceans and Life in the Oceans Pertemuan ke-2 (Asal-usul bumi, laut dan...

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