Origin of the Universe

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Origin of the Universe

• Understanding Earths uniqueness

2
Planetary evolution

• Where does water come from?
• Why do we have oceans?
• Why do we have life as we know it?
• Elemental composition
• Present day configuration relative to origins
• Hydrological cycle
• Dissolved gases/Ocean and Atmosphere

3
How did the earth become habitable?

• How did Earth evolve?
• What makes it different from other planets?

4
Origin of the universe

• Importance of time scales
• Forces at work in the past some changes as
  planet evolved
• Forces at work today
• How can we measure age of the earth

5
How old is Earth?

• Biblical scholars of 19th century (Bishop Ussher)
  6000 years (started at 4004 BC)
• Classical Greeks infinite history endlessly
  repeats itself
• Mayans believed earth recycled on a 3000 year
  time scale
• Han Chinese thought earth was recreated every
  23,639,040 years
• The age we now except may change but is
  consistent with current theory

6
More recent efforts

• Lord Kelvin - 80 million years old based on
  cooling of molten Earth
• Darwin - really old based on time for natural
  selection (biological argument)
• Hutton really old based on uniformitarianism
  (processes in the past taking place at rates
  comparable to today) (geological argument)

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Earths age

• Earth is about 4.5 (or 4.6) BY old
• First 700 MY Earth was a spinning cloud of gas,
  dust and planetoids
• These condensed and settled to solidify into a
  series of planets
• Since that time, geological history and evolution
  commenced.

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Formerly oldest life
Oldest life?
9
The Big Bang Theory

• Currently the dominant theory
• First iteration proposed by Georges Lemaître in
  1927. He observed the red shift in distant
  nebulas and invoked relativity.
• Hubble found experimental evidence (1929)
  galaxies are moving away from us with speeds
  proportional to their distance.
• Theory suggested because it explains the
  expansion predicts the existence of cosmic
  radiation (leftover photons) nucleosynthesis
• 1964 cosmic radiation discovered (Arno Penzias
  Robert Wilson who won the Nobel Prize)

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Big Bang what is it?

• Collapsing cloud of interstellar dust
• Cloud dense and cold so collapses under its own
  self-gravity (cold gas has less internal pressure
  to counteract gravity)
• Once collapsed, it immediately warms up because
  of release of gravitational energy during
  collapse
• All mass and energy concentrated at a geometric
  point

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Big Bang

• 14 or 15 BY ago
• Beginning of space and time
• Expansion/cooling of universe began
• Protons and neutrons form
• Cooling initiated the formation of atoms first
  mostly H (the most abundant form of matter in the
  universe) and He (two lightest elements)

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The universe

• H2 and He gas are still the dominant elements in
  the universe
• Still about 99 of all material
• Giant gas and dust clouds form
• Clouds begin to break into megaclouds
• Megaclouds organized into spiral and elliptical
  shapes due to rotational forces
• Galaxies or nebulae are the gases and dust in the
  disk
• Some of the gas in these galaxies broke up into
  smaller clusters to form stars
• Gravitational collapse of stars produces heat
• Initiates fusion reactions that make other
  elements

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The Eagle Nebula from the Hubble telescope
Interstellar clouds
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Formation of galaxy and stars

• Galaxy rotating aggregation of stars, dust, gas
  and debris held together by gravity
• Stars are massive spheres of incandescent gases
• 100s of billions of galaxies in the universe
  and 100s of billions of stars in the galaxies
• Sun is a star
• Sun plus its family of planets is our solar
  system
• Our solar system formed about 5 BY ago

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• Our galaxy is out in a spiral arm
• Our solar system orbits the galaxys core
• (230 million year orbit at 280 km/s)

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Formation of the Sun

• Clouds in interstellar space are many 1000s of
  times the mass of the sun
• Clouds contract, producing smaller fragments
• Form 1 or more star depending how fast the
  cloud fragment is rotating (faster yields more
  stars)

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The disk around the star Beta Pictoris as seen
from the Hubble Space Telescope) real and
false color
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Stars

• Stars form in nebulae, large diffuse clouds of
  dust and gas.
• Condensation theory spinning nebula starts to
  shrink and heat under its own gravity
• Protostar condensed gases
• At temperature of 10 million degrees C, nuclear
  fusion begins (Hs fuse to form He) which
  releases energy and stops shrinkage
• Star is stable once fusion reactions begin (form
  atoms as heavy as C and O)

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Our sun in 5 by
Our sun eventually
Star classification most fall along main
sequence band and are normal
Effective radiating temperature calculated using
Weins law Brightest bluest and most massive are
O and B, early type stars (left) Dimmest, reddest
and least massive are K and M, late type
stars Our sun is a G2 star
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Element synthesis

• Series of fusion reactions producing elements up
  to Fe
• Fusion reactions convert a small amount of mass
  to heat
• Heats up star
• Increases stars density
• Combine to increase core temperature

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Beginning of the end

• Star starts consuming heavier atoms increasing
  energy output and swelling to a red giant
• Nuclear fuel in core is spent
• Incinerates planet and throws off matter
  including heavy elements
• More massive stars get hotter and consume H at
  higher rates and make heavier atoms (e.g., Fe)

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The end

• H is consumed
• Core collapses on itself
• Internal temperatures sore so can no longer
  contract
• Star implodes
• Cataclysmic expansion called a supernova (30 sec)
• Mass is accelerated outward
• Forces holding apart atomic nuclei are overcome
• Produces free neutrons
• Heavier atoms formed by neutron capture

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Heavy elements

• Reactions produce stable and radioactive elements
• Radioactive elements important for planetary
  evolution
• Internal heat source driving plate tectonics
• Elemental composition

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Abundance of Fe

• Fe is abundant in cores of stars that explode
• Nuclear physics dictates that this element is the
  most stable element that can form via fusion
  reactions
• Formation of other elements requires fission
  reactions or reactions with free neutrons
• Fe accumulates in the core before it explodes
• Other lower mass elements occur in supernovae
  debris since core is still burning other elements
• General decrease in elemental abundance up to Fe
  and accumulation of Fe

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Our Solar System

• Our solar nebula was struck by a supernova
• Caused our condensing nebula to spin
• Introduced heavy atoms to seed the formation of
  planets
• 5 BY ago, the solar nebula was 75 H, 23 He and
  2 other material
• Center became protosun
• Outer material became planets smaller bodies
  that orbit a star but do not shine by their own
  light

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Chemical composition of Sun

• Our sun did not form early after the big bang
• Contains elements that could only form during
  death of a red giant (elements beyond Fe)
• Gasses and dust from explosion of a red giant
  condensed to form our sun
• Same material that formed the sun also formed the
  planets
• Earth and terrestrial planets are also
  predominantly Fe, Mg, Si, and O

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Our solar system

• Most of the material in the cloud that formed our
  sun ended up in the sun
• Chemical elements in sun similar to elements in
  universe
• Some material ended up in the nebular disk around
  the sun
• Formed planets, moon, asteroids, comets
• This material was different in chemical
  composition
• Elements that were contained in dust and ice
  formed planets
• Gasses not retained by sun were largely lost
• Exception is some of the large, gassy outer
  planets

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Planets

• Grew by accretion big clumps use gravitational
  pull to accrete condensing matter
• Near sun, first materials to solidify had higher
  boiling points (metals and rocky minerals)
  Mercury is mostly Fe, Ni. Inner rocky planets.
• Next Mg, Si, H2O and O2 condensed (plus some Fe
  and Ni). Middle planets (e.g., Earth).
• CH4 and NH3 in frigid outer zones. Outer gassy
  planets (Jupiter, Saturn, Uranus and Neptune).

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Stabilization of solar system

• Protosun became star (sun) and nuclear fusion
  began
• Solar wind (radiation) at the start of those
  reactions cleared excess particles and ended
  rapid accretion of inner planets.

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Our solar system

• Collapse of nebular cloud that had been hit by a
  red giant to form our sun
• Nuclear reactions commenced
• Chemical fractionation of planets circling new
  sun
• Hot inner region of the ring
• Loss of volative elements
• Inner planets retained metals and oxides that can
  condense at high temperatures
• Cold outer region of the ring
• Accumulation of ices and gasses
• Gasses accumulated in large outer planets because
  their cores accreted fairly early and their
  gravitational attraction due to their masses was
  sufficient to retain gases.

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Terrestrial planets

• Mercury, Venus, Earth and Mars
• Nuclear physics sets relative abundance of
  elements and inorganic chemistry controls the
  chemical forms of these elements
• Elements that form gasses largely lost from
  planets as compared to chondrites
• Elements forming oxides largely retained
• Some loss due to volatilization
• Chondrites found in meteors and thought to
  represent original material that formed the
  planets
• Oxygen and sulfur are exceptions have gaseous
  and solid forms

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Early Earth

• Homogeneous throughout during initial accretion
  of cold particles
• Surface heated by impacts (asteroids, comets and
  debris) first 500 my
• Heat, gravitational compression, radioactive
  decay caused partial melting.
• Density stratification.
• Gravity pulled heavy
• elements to interior.
• Friction during this
• produced more heat.
• Lighter minerals (Si,
• Mg, Al and O-bonded
• compounds) migrated to
• surface forming Earths
• crust.

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Timeline (since big bang)

• 10-35 sec ABB (The Big Bang)
• The universe is an infinitely dense, hot
  fireball.
• 10-6 sec ABB (1 millionth of a second)
• Universe forms Expansion slows down universe
  cools and becomes less dense
• The most basic forces in nature become distinct
  first gravity, then the strong force, which holds
  nuclei of atoms together, followed by the weak
  and electromagnetic forces. By the first second,
  the universe is made up of fundamental particles
  and energy quarks, electrons, photons, neutrinos
  and less familiar types. These particles smash
  together to form protons and neutrons.

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• 3 sec ABB
• Formation of basic elements
• Protons and neutrons come together to form the
  nuclei of simple elements hydrogen (1 proton),
  helium (2 protons) and lithium (3 protons) (1, 2
  and 3 in periodic table). It will take another
  300,000 years for electrons to be captured into
  orbits around these nuclei to form stable atoms.
• 10,000 yr ABB
• Radiation Era
• The first major era in the history of the
  universe is one in which most of the energy is in
  the form of radiation -- different wavelengths of
  light, X rays, radio waves and ultraviolet rays.
  This energy is the remnant of the primordial
  fireball, and as the universe expands, the waves
  of radiation are stretched and diluted until
  today, they make up the faint glow of microwaves
  which bathe the entire universe.

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• 300,000 yr ABB
• Matter dominates
• The energy in matter and the energy in radiation
  are equal. As universe expands, waves of light
  are stretched to lower and lower energy, while
  the matter travels onward largely unaffected.
  Neutral atoms are formed as electrons link up
  with hydrogen and helium nuclei. Microwave
  background radiation gives us a direct picture of
  how matter was distributed at this early time.
• 300 MY ABB
• Birth of stars and galaxies.
• Gravity amplifies slight irregularities in the
  density of the primordial gas. Even as the
  universe continues to expand rapidly, pockets of
  gas become more and more dense. Stars ignite
  within these pockets, and groups of stars become
  the earliest galaxies. (Still perhaps 12 to 15
  billion years before the present).

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• 5 BY ago Birth of the Sun
• The sun forms within a cloud of gas in a spiral
  arm of the Milky Way Galaxy. A vast disk of gas
  and debris that swirls around this new star gives
  birth to planets, moons, and asteroids . Earth is
  the third planet out.
• The image on the left, from the Hubble Space
  Telescope, shows a newborn star in the Orion
  Nebula surrounded by a disk of dust and gas that
  may one day collapse into planets, moons and
  asteroids.
• 3.8 BY ago Earliest Life
• The Earth has cooled and an atmosphere develops.
  Microscopic living cells, neither plants nor
  animals, begin to evolve and flourish in earth's
  many volcanic environments.
• 700 MY ago Primitive Animals appear
• These are mostly flatworms, jellyfish and algae.
  By 570 million years before the present, large
  numbers of creatures with hard shells suddenly
  appear.
• 200 MY ago Mammals appear
• The first mammals evolved from a class of
  reptiles that evolved mammalian traits, such as a
  segmented jaw and a series of bones that make up
  the inner ear.

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• 65 MY ago Dinosaurs become extinct
• An asteroid or comet slams into the northern part
  of the Yucatan Peninsula in Mexico. This
  world-wide cataclysm brings to an end the long
  age of the dinosaurs, and allows mammals to
  diversify and expand their ranges.
• 600,000 yr ago Homo sapiens evolve
• Our earliest ancestors evolve in Africa from a
  line of creatures that descended from apes.
• 170,000 yr ago Supernova 1987a explodes
• A star explodes in a dwarf galaxy known as the
  Large Magellanic Cloud that lies just beyond the
  Milky Way. The star, known in modern times as
  Sanduleak 69-202, is a blue supergiant 25 times
  more massive than our Sun. Such explosions
  distribute all the common elements such as
  Oxygen, Carbon, Nitrogen, Calcium and Iron into
  interstellar space where they enrich clouds of
  Hydrogen and Helium that are about to form new
  stars. They also create the heavier elements
  (such as gold, silver, lead, and uranium) and
  distribute these as well. Their remnants generate
  the cosmic rays which lead to mutation and
  evolution in living cells. These supernovae,
  then, are key to the evolution of the Universe
  and to life itself.

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• 1054 Crab Supernova appears
• A new star in the constellation Taurus outshines
  Venus. Chinese, Japanese, and Native American
  observers record the appearance of a supernova.
  It is not, however, recorded in Europe, most
  likely as a consequence of lack of study of
  nature during the Dark Ages. The remnants of this
  explosion are visible today as the Crab Nebula.
  Within the nebula, astronomers have found a
  pulsar, the ultra-dense remains of a star that
  blew up.
• 1609 Galileo builds first telescope
• Five years after the appearance of the great
  supernova of 1604, Galileo builds his first
  telescope. He sees the moons of Jupiter, Saturn's
  rings, the phases of Venus, and the stars in the
  Milky Way.
• 1665 Newton describes gravity
• At the age of 23, young Isaac Newton realizes
  that gravitational force accounts for falling
  bodies on earth as well as the motion of the moon
  and the planets in orbit. This is a revolutionary
  step in the history of thought, as it extends the
  influence of earthly behavior to the realm of the
  heavens. One set of laws, discovered and tested
  on our planet, will be seen to govern the entire
  universe.

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• 1905 Einsteins Theory of Relativity
• Relativity recognizes the speed of light as the
  absolute speed limit in the universe and, as
  such, unites the previously separate concepts of
  space and time into a unified spacetime. Eleven
  years later, his General Theory of Relativity
  replaces Newton's model of gravity with one in
  which the gravitational force is interpreted as
  the response of bodies to distortions in
  spacetime which matter itself creates.
  Predictions of black holes and an expanding
  Universe are immediate consequences of this
  revolutionary theory which remains unchallenged
  today as our description of the cosmos.

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• 1929 Hubble discovers universe is expanding
• Edwin Hubble discovers that the universe is
  expanding. The astronomer Edwin Hubble uses the
  new 100-inch telescope on Mt. Wilson in Southern
  California to discover that the farther away a
  galaxy is, the more its light is shifted to the
  red. And the redder a galaxy's light, the faster
  it is moving away from us. By describing this
  "Doppler shift," Hubble proves that the universe
  is not static, but is expanding in all
  directions. He also discovers that galaxies are
  much further away than anyone had thought.
• 1960 Quasars discovered
• Allan Sandage and Thomas Matthews find sources of
  intense radio energy, calling them Quasi Stellar
  Radio Sources. Four years later, Maarten Schmidt
  would discover that these sources lie at the edge
  of the visible universe. In recent years,
  astronomers have realized that they are gigantic
  black holes at the centers of young galaxies into
  which matter is heated to high temperatures and
  glows brightly as it rushes in.
• 1964 Microwave radiation discovered
• Scientists at the Bell Telephone Laboratories
  discovered microwave radiation that bathes the
  earth from all directions in space. This
  radiation is the afterglow of the Big Bang.

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• 1967 Discovery of Pulsars
• A graduate student, Jocelyn Bell, and her
  professor, Anthony Hewish, discover intense
  pulsating sources of radio energy, known as
  pulsars. Pulsars were the first known examples of
  neutron stars, extremely dense objects that form
  in the wake of some supernovae. The crab pulsar,
  is the remnant of the bright supernova recorded
  by Native Americans and cultures around the world
  in the year 1054 A.D.
• 1987 Light from supernova 1987 reaches Earth
• The light from this supernova reaches earth,
  170,000 years after is parent star exploded.
  Underground sensors in the United States and
  Japan first detect a wave of subatomic particles
  known as neutrinos from the explosion.
  Astronomers rush to telescopes in the southern
  hemisphere to study the progress of the explosion
  and perfect models describing the violent deaths
  of large stars.

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• 1990 Hubble launched
• The twelve-ton telescope, equipped with a 94-inch
  mirror, is sent into orbit by astronauts aboard
  the space shuttle Discovery. Within two months, a
  flaw in its mirror is discovered, placing in
  jeopardy the largest investment ever in
  astronomy.
• 1990 Big Bang confirmed
• Astronomers use the new Cosmic Background
  Explorer satellite (COBE) to take a detailed
  spectrum of the microwave background radiation.
  These studies showed that the radiation is in
  nearly perfect agreement with the Big Bang
  theory. Two years later, scientists used the same
  instrument to discover minute variations in the
  background radiation the earliest known evidence
  of structure in the universe.
• 1993 Hubble optics repaired
• Hubble's greatest legacy so far detailed images
  of galaxies near the limits of the visible
  universe.

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Future

• 100 Trillion
• Astronomers assume that the universe will
  gradually wither away, provided it keeps on
  expanding and does not recollapse under the pull
  of its own gravity. During the Stelliferous Era,
  from 10,000 years to 100 trillion years after the
  Big Bang, most of the energy generated by the
  universe is in the form of stars burning hydrogen
  and other elements in their cores.
• 1037 yrs
• Most of the mass that we can currently see in the
  universe is locked up in degenerate stars, those
  that have blown up and collapsed into black holes
  and neutron stars, or have withered into white
  dwarfs. Energy in this era is generated through
  proton decay and particle annihilation.

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• 1038 to 10100 The Black Hole Era
• After the epoch of proton decay, the only
  stellar-like objects remaining are black holes of
  widely disparate masses, which are actively
  evaporating during this era.
• 10100 Dark Era Begins
• At this late time, protons have decayed and black
  holes have evaporated.Only the waste products
  from these processes remain mostly photons of
  colossal wavelength, neutrinos, electrons, and
  positrons. For all intents and purposes, the
  universe as we know it has dissipated.
• From PBS Online (http//www.pbs.org/deepspace/ti
  meline/)

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Aging the Earth Solar System

• Oldest rocks on earth about 4.1 bybp (zircons)
• Material in solar system appears older (4.55
  bybp)
• Dating meteorites, chunks of rock and metal,
  formed about the same time as the sun and planets
  and from the same cloud.
• Carbonaceous chondrites are a class of meteorites
  believed to be the most primitive in the solar
  system (silicate minerals, water and carbon)
• Dating moon rocks and oldest rocks found on Earth
  (about 3.8 BY old)
• Rate of expansion (2002, astronomers had very
  accurate measurements and calculated backwards to
  an age of 13-14 BY old).

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How do we age things?

• Isotopic decay
• Radioisotopes are unstable and decay to form
  daughter products which form next to parent
  nuclide.
• Know the ratio of daughter to parent in
  undisturbed sample and the rate of conversion
  (e.g., decay rate or half-life) allows
  computation of age
• This has been done with several isotope pairs to
  arrive at age of solar system

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Isotopes

• The ordinary isotope of hydrogen, H, is known as
  Protium, the other two isotopes are Deuterium (a
  proton and a neutron stable) and Tritium (a
  protron and two neutrons unstable). Hydrogen is
  the only element whose isotopes have been given
  different names.
• Radioactive decay spontaneous disintegration of
  unstable nuclei
• For low atomic number elements stable is about
  11 neutronsprotons in the nuclei. For higher
  atomic number elements, the ratio is about 1.61.
• Heavy nuclides (atomic number gt 82) have no
  stable configuration.
• Different types of decay
• FYI Fusion of hydrogen into helium provides the
  energy of the hydrogen bomb

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Some isotopes
Parent isotope Daughter Isotope Half Life
238U 206Pb 4.47 x 109 years
235U 207Pb 7.04 x 108 yrs
232Th 208Pb 1.40 x 1010 yrs
87Rb 87Sr 4.88 x 1010 yrs
40K 40Ar 1.25 x 109 yrs
39Ar 39K 269 yrs
14C 14N 5,730 yrs
147Sm 147Nd 1.06 x 1011 yrs
daughters are smaller and contain fewer protons,
neutrons electrons
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• Date chondritic meteorites
• Pb isochron approach
• pairs of isotopes for relativity
• Timeclocks set at point of
• crystalization
• Earth formed over time period
• as solar material accumulates
• in planet as dust, rock and
• planetessimals this took 10
• 100 my (based on calculations)

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Doppler shifting

• Wavelengths emitted by objects moving away are
  shifted to lower frequency (towards reds)
• Wavelengths emitted by objects moving towards us
  are shifted to higher frequency.
• Example of sound pitch of fire engine is higher
  as truck moves towards you and lower as it moves
  away)
• For galaxies outside our group, the redshift is
  known as hubble expansion (after Edwin Hubble who
  discovered this phenomenon in 1929).

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Another way to look at time

• 0-7 No record (no baby pics)
• 8-12 First rocks formed that are preserved today
• 12 First living cell appeared
• 22-23 Oxygen appeared
• 31 Atmosphere becomes oxygenated
• 40 First fossils formed (earlier records
  are dubious)
• 41 First vertebrates
• 41.7 First land plants
• 43 First reptiles
• 45 First flowering plants
• 45.6 Mammals, birds, insects became dominant
• 25 days ago First human ancestors
• 0.5 hours ago Civilization began
• 1 min ago Industrial revolution began
• Geologic Time Appendix II

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The origin of life

• Next time

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Emerging field

• Exobiology
• Carbonaceous chondrites
• Primordial soup
• Reducing environments
• polymerization

• Composition of a cell
• 59 H
• 24 O
• 11 C
• 4 N
• 2 Others (P, S, etc)

• Composition of a cell
• 50 protein
• 15 nucleic acid
• 15 carbohydrates
• 10 lipids
• 10 other