Title: Origin of the Universe
1Origin of the Universe
- Understanding Earths uniqueness
2Planetary 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
3How did the earth become habitable?
- How did Earth evolve?
- What makes it different from other planets?
4Origin 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
5How 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
6More 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)
7Earths 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.
8Formerly oldest life
Oldest life?
9The 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)
10Big 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
11Big 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)
12The 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
13The Eagle Nebula from the Hubble telescope
Interstellar clouds
14Formation 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
15- Our galaxy is out in a spiral arm
- Our solar system orbits the galaxys core
- (230 million year orbit at 280 km/s)
16Formation 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)
17The disk around the star Beta Pictoris as seen
from the Hubble Space Telescope) real and
false color
18Stars
- 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)
19Our 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
20Element 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
21Beginning 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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23The 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
24Heavy 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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26Abundance 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
27Our 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
28Chemical 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
29Our 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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31Planets
- 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).
32Stabilization 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.
33Our 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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35Terrestrial 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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37Early 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.
38Timeline (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.
39- 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.
40- 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).
41- 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.
42- 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.
43- 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.
44- 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.
45- 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.
46- 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.
47- 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.
48Future
- 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.
49- 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/)
50Aging 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).
51How 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
52Isotopes
- 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
53Some 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
54- 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)
55Doppler 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).
56Another 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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58The origin of life
59Emerging 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