Transcript Origin of the Universe

Lava lamp
Introduction
We will consider all spheres of Earth
– Rock – Geology
Atmosphere – Air - Meteorology & Climatology
Hydrosphere – Water – Oceanography
Biosphere – Life - Biology
Lithosphere
http://www.hcsi.com/im_lib/space/geosna.jpg
Our goal is to understand interactions between spheres
First, we must agree on a method of work
Scientific Method
• Hypothetico-deductive framework
• Hypotheses have testable consequences
• We test hypotheses to try to falsify them
• Karl Popper
http://www.eeng.dcu.ie/~tkpw/
1934 Popper Logic of
Scientific Discovery
Falsification
biography of
Book: The_Structure_of_Scientific_Revolutions (1962)
• Paradigm shifts
http://en.wikipedia.org/wiki/Aristotle
An example: The earth’s orbit
• The Greek philosophers including Aristotle
(384 BC - 322 BC ) observed the Sun rising in
the east and setting in the west and inferred that
the Sun revolved around Earth in a geocentric
(Earth-centered) orbit.
Galileo's Letter to the Prince of Venice
http://www.mira.org/fts0/planets/099/text/txt002x.htm
Aristotle’s model is wrong
Europa
Io
• Galileo’s observations of the orbits of Jupiter’s four largest satellites
revealed that the Aristotle-Ptolemy model is unbelievable
• Objects that do not orbit the Earth
• We now know that the planets, including the Earth, orbit the Sun
Callisto
Ganymede
http://www.hcsi.com/im_lib/imlib_space.html
http://www.enchantedlearning.com/subjects/astronomy/planets/jupiter/moons.shtml
A new law
Isaac Newton (1665) discovered the force that
held the planets in their orbits around the sun gravity.
 gravitation, "every body in the universe attracts
every other body.“
 Force = mass x acceleration = ma
identify symbols
 Gravitational Force = gm1m2/r2

Both orbit, but …
 Sun
is much more massive, appears to
hold still while the earth orbits around it.
 We will see “g” again
How Far Away?
• We use the speed of light to indicate distance – light
years 9460 billion kilometers
• Nearby Cepheids (variable stars) maximum brightness
varies with period
• Measure apparent brightness and get distance
of far away Cepheids
• Our galaxy, the Milky Way, is 100,000 light years
across (diameter)
Continuous, Emission and
Absorption Spectra
White light contains a continuum of colors from short wave violet to long wave red
Hot, dense materials emit discrete "emission" spectra
Hydrogen
When light with a continuous spectrum passes through a
cold, rarefied gas, an absorption spectrum results.
Each gas absorbs the same wavelengths that it emits when it is hot.
The spectrum of the light from our Sun is an Absorption spectrum.
Helium
Redshift: absorption spectra shift to
red with retreat of the emitter
Analogy: Passing train whistle, high to low frequency = short to long wavelength
“Doppler Effect”
Blue, moving toward us
Very distant objects aren’t just
single stars, those are galaxies
of stars! Hubble: What if their
colors reflect their speed and
direction?
Red, very distant, moving away fast
Hubble Space Telescope
http://en.wikipedia.org/wiki/Edwin_Hubble
The Hubble Redshift
• Hubble discovered that the most distant
galaxies with Cepheids had their light
shifted to the red end of the spectrum. This
meant that they are moving away from us.
red and
far object
• Hubble: Turn this into aVery
new
yardstick:
the
redder the shift, the further the galaxy
• Result: the edge of the universe (furthest
objects we can detect) is approximately 15
billion light years away.
http://skyserver.sdss.org/astro/en/proj
/advanced/hubble/conclusion.asp
Origin of the Universe

The spectral shift of light coming from distant
galaxies tells us that the universe is expanding
out of a very small volume that began at most
15 billion years ago

Estimates vary according to method

The universe expanded from a state of pure
energy, hydrogen atoms condensed from
energy in a process called nucleosynthesis
E=mc2
Origin of the Elements
• Very small volume expands “Big Bang”
• A few minutes energy cools to form H
• Hydrogen gas clouds condensed to form
main sequence stars.
• H fuses to form He and heavier atoms
• “Main sequence stars” form Oxygen and
Carbon.
Water = 2 Hydrogen + 1 Oxygen
H2O
Symbols for elements
Origin of Heavy Elements
• A star more than 8-20 times the mass of
our sun burns faster, then expands into a
red super giant star, similar to Betelgeuse.
• Pressure is high enough to also produce
the heavier elements including silicon Si,
magnesium Mg, iron Fe.
• Once its fuel is exhausted,
a supernova explosion occurs.
http://www.solarviews.com/cap/ds/betelgeuse.htm
8
14
Most rocks are
made of these two
Main Sequence Stars
Super Giant
Stars
Origin of Our Solar System
• Our solar system with its abundant
collection of heavier elements condensed
from the gas cloud left after the explosion
of a supernova.
Supernova ejects matter-rich
pressure waves into space
Local concentrations of dust
coalesce
Balance between gravity
and solar wind
During coalescence:
Particles assemble
due to gravity –
heat up
Iron melts and
begins to sink
Lighter materials
concentrate
closer to surface
1_7
Planetesimals
strike growing
Earth
1. Rub your hands together.
Motion (“kinetic”) energy
is converted to heat.
DIFFERENTIATION
Crust and
mantle
Liquid
core
Atmosphere
Crust
Mantle
Outer core
Inner core
The moon formed
after a Mars-sized
planet hit earth,
about 4.6 bya
We got most of the
core material in the
exchange
Earth’s Internal Structure
• Earth’s internal layers defined by
– Chemical composition
– Physical properties
– Deduced from Seismographs of Earthquakes
– Meteorites lend support
• Layers defined by composition
– Crust
– Mantle
– Core
Iron-Nickel Meteorite
Earth’s internal structure
• Main layers of Earth are based on physical properties
including mechanical strength
• Outer layers mostly Silicate Minerals: Crust and
Mantle
• Lithosphere (behaves like a brittle solid)
Crust and uppermost mantle
• Asthenosphere “weak sphere”
Rest of Upper Mantle
Heat softened, plastic solid
• Lower Mantle
Solid due High Pressures
• Inner Layers Core Iron and Nickel,
outer core hotter than melting point - liquid,
inner core solid due to high pressures
CRUST
(least dense)
Upper mantle
Note progression of densities
MANTLE
Oil and water
Continental crust
Oceanic crust
1_8
0 km
~100 km
~350 km
Lower mantle
Lithosphere
Asthenosphere
CORE
(most dense)
Outer
core
~5155 km
Inner
core
~2900 km
Conversion Factors
6370 kilometers to the center of the Earth
6370 km x 5 miles/8 km = 3981.25 miles
Earth has a radius of about 4000 miles
Liquid Outer Core causes
Magnetic Field
“Lithosphere”
“Asthenosphere”
Earth has a large liquid outer core, makes a magnetic field, and so a thick atmosphere
The Magnetic Field protects the
Atmosphere. The Atmosphere
protects Earth from most meteors
Origin of magnetic field: the liquid outer core
An Important Magnetic Field
A magnetic field once surrounded Mars. The red planet lost its protective
magnetic field as the smaller planet cooled down more rapidly than Earth,
losing its hot liquid core. Mars retains just isolated remnants of its atmosphere
where pockets of relict magnetism remain.
A Perfect Spot
 Earth's distance from the Sun allows water to exist as a
liquid.
 The biosphere of Earth has moderated the composition of
the atmosphere to make it more suitable for life. Vegetation
absorbed large volumes of carbon dioxide and produced
oxygen O2
and Ozone O3.
 Earth's atmospheric gases protect the planet from all but
the largest incoming space projectiles (comets, meteorites)
and ozone blocks harmful ultraviolet radiation from the Sun
The Geothermal Gradient
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The temperature gradient in the crust averages
approximately 25oC per kilometer.
Varies with location (higher in areas of volcanic
activity) and depth
Shows the interior of the planet is much hotter
than the exterior.
Volcanism an indication that heat is being
transferred from the interior toward the surface.
Heat transfer occurs by convection, radiation
and conduction. (define)
From the Asteroid Belt to Earth
• The gravitational attraction of Jupiter , or
passing comets, jostles asteroids from
their asteroid belt orbits causing collisions
• Sends asteroids toward the inner planets.
Barrington Crater
Winslow, Arizona
• Impacts with earth, moon and terrestrial
planets have left scars that can still be
observed today
Comets – dirty snowballs – are jostled loose from the Oort Cloud and fall toward the Sun
A Dirty Comet Impact in 1908 -- No Crater
2100 km2 flattened
http://en.wikipedia.org/wiki/Tunguska_event
The Tunguska Event
• Had the object responsible for the
explosion hit the Earth a few hours later, it
would have exploded over Europe (most
probably Scandinavia) instead of the
sparsely-populated Tunguska region,
producing massive loss of human life and
changing the course of human history
K-T Mass Extinction A Crisis in the History of Life

Cretaceous-Tertiary extinction
claimed dinosaurs, flying reptiles,
marine reptiles, and many marine
invertebrates
Chicxulub impact structure on
the Yucatan Peninsula, Mexico
65 mya this event placed dust in the atmosphere
and started fires that killed 70% of all species
The dust is found in a thick layer worldwide, and forms the K|T boundary
the boundary between the Age of Reptiles and the Age of Mammals.
Gravity Map
http://en.wikipedia.org/wiki/Chicxulub_Crater
The K\T ash layer in Alberta
Shocked Quartz
Luis and Walter Alvarez
The consequences of a Chicxulub
• Powerful air blast flattens everything for thousands of
square kilometers
• Massive earthquake 100 to 1000 x greater than historical
times
• Deep crater 10-20 x object diameter
• Massive plume of dust into atmosphere.
blocking sunlight
• Lower temperatures and a short-term cooling trend.
• Earth in darkness prevents photosynthesis for the next
year.
• Vegetation would not survive
• Colossal wildfires that would add smoke to the rapidly
darkening skies.
• Giant tsunami waves with heights up to 2 miles) would be
possible from a Chicxulub-sized event in the deep ocean.
NASA's
annual
budget for
detection of
NEOs:
$3 million
One
superfund
cleanup
$21 million
The End of the Age of Reptiles
65 million Years Ago
Okay, that’s enough background. During WWII ships with depth sounders crisscrossed the earth’s oceans
The Geology Paradigm
What is That?
Continental drift: An
idea
before its time
• Alfred Wegener
• Proposed hypothesis in 1915
• Published The Origin of
Continents and Oceans
• Continental drift hypothesis
• Supercontinent Pangaea began breaking
apart about 200 million years ago
South American and African
Coastlines Fit
Fossils, mountain ranges, glaciers
Harry Hess
The revolution begins
• During the 1940s and 1950s technological
advances permitted mapping of the ocean
floor. Hess was captain of a minesweeper
with sonar. Left it on all WWII.
• Seafloor spreading hypothesis was proposed
by Harry Hess in the early 1960s.
http://www.amnh.org/education/resources/rfl/web/essaybooks/earth/p_hess.html
Remember Arthur Holmes
Convection, the basic idea of Plate Tectonics, Atmospheric Cells, and Ocean Currents
http://www.gfdl.noaa.gov/~io/Bubble.html
Start with a hot
bubble, it expands and
so is less dense. It
rises as surrounding
dense material
presses on it,
especially at deeper,
higher pressure,
levels. When it hits a
barrier it spreads,
cools and becomes
denser. It sinks and
returns material to the
start.
Bubble Convection ( i.e. the lava lamp model)
Harry’s Idea:
Sea-Floor
Spreading
1_20
Convection cells in the hot mantle hit the
lithosphere barrier. They spread out and cool,
pulling the lithosphere apart. New lava gets into the
cracks, filling the gap, and FORMING NEW
OCEAN CRUST!
Mid-ocean
ridge
How Can We Test Harry’s Hypothesis?
Some mineral crystals
in solidifying lava align
with Earth’s magnetic
field. Tilt tells latitude.
Earth’s North –South
Poles can flip. Tilt will
change direction
New lava rock will have
the signature of the
magnetic field when it
froze
Fred Vine and Drummond Matthews: Harry’s idea is A TESTABLE HYPOTHESIS
Paleomagnetic reversals would be recorded
by lava (called basalt) at mid-ocean ridges
New lava rock will have the
signature of the magnetic
field when it froze
Maps of Magnetic Stripes in Oceanic Crust
Princeton PostDoc Fred Vine
and Drummond Matthews
Did they prove Harry’s idea?
Harry Hess’s Seafloor Spreading developed into
Plate tectonics: The new paradigm
• More encompassing theory than
Wegener’s continental drift
• Explains motion of Earth’s lithosphere
by seafloor spreading (creation of new
ocean floor) and subduction (destruction
of old ocean floor)
• All major earth features are explained
The Asthenosphere boils, like soup. This moves the cold Lithosphere PLATES above
Lithosphere is "the scum floating
on top of the boiling soup"
Here we see Divergent Margins (the Atlantic Mid-Ocean Ridge – Harry’s Sea-Floor
Spreading) and
Convergent Margins (the dense Pacific Ocean Plate is being dragged under South
America – called subduction zones )
Continental Lithosphere
Oceanic Lithosphere
Asthenosphere
Subduction Zone
Divergent Boundaries (Rising Convection Currents) Mid-Ocean Ridge
Convergent Boundaries
(Descending Convection Currents)
Subduction Zone
Mantle material rises, ponds under the lithosphere,
spreads, pulls the lithosphere apart. Mantle minerals
exposed to low pressures. Some mantle minerals are unstable at low pressures.
They melt, forming lavas, which get into the cracks, and cool into basalt,
the main rock of ocean lithosphere.
180º
90º
0º
90º
180º
Mid-Atlantic
Ridge
1_15
45º
45º
NORTH
AMERICAN
PLATE
JUAN DE
FUCA
PLATE
EURASIAN
PLATE
ARABIAN
PLATE
CARIBBEAN
PLATE
PACIFIC
PLATE
PHILIPPINE
PLATE
AFRICAN
PLATE
COCOS
PLATE
0º
PACIFIC
PLATE
FIJI
PLATE
SOUTH
AMERICAN
PLATE
NAZCA
PLATE
SCOTIA
PLATE
45º
0º
Mid-Atlantic
Ridge
INDIANAUSTRALIAN
PLATE
45º
ANTARCTIC PLATE
180º
Convergent plate
boundary
Divergent plate
boundary
Transform plate
boundary
ANTARCTIC PLATE
90º
0º
90º
180º
Seven or so major plates, about an equal number of small plates
Components of Plate Tectonics: there are three main types of plate margins
Divergent, Convergent and Transform
Each plate bounded by combination of all
three boundary types
Divergent boundaries are located
mainly along Mid-Ocean Ridges
(MORs)
The East African Rift
MORs can start
as rift valleys, the
dry land precursor
of mid-ocean
ridges.
Soon enough they
connect to the
sea, and flood,
forming a new
ocean
Convergent Plate Boundaries
If Seafloor Spreading (Divergence) is occurring somewhere,
plates must push against one another in other areas
Oceanic lithosphere
being subducted
(a)
Subducted Ocean Plate loses water and adjacent Mantle partially
melts, new buoyant magma rises to the surface, forming a
Volcanic Arc such as the Andes Mountains of South America
Once the ocean crust between them is subducted, the continents collide.
Both are thick and made of buoyant (low density) minerals, so neither
continent can be subducted under the other
Collisional
mountains
Rocks deformed in collision
(b)
Collisions formed the Appalachians, and, more recently,
the Himalayas and the Alps.
Suture
The collision of India and Asia
produced the Himalayas
1. Subduction Zone Phase
2. Collision Phase
Convergent Boundaries
Types
Products
Ocean-Continent
Andes, Cascades
Favorite quiz picture
Ocean-Ocean
Japan, Aleutians
Asia
India
Continent-Continent
Himalayas, Alps,
Appalachians
Transform
Plate
Boundaries
Transform Margins accommodate movement
as plates slide past one another, for example
the San Andreas Fault and between MidOcean Ridge segments
Plate Tectonics Explains It All
• The Plate Tectonic concept caused the
realization that Earth’s many geologic features
were all caused by the same process.
• We now understand mountains, volcanoes, and
big earthquakes associated with, for example,
the San Andreas fault.
• We understand rift valleys and how oceans form,
deep ocean trenches, mid-ocean ridges, and
why fossils and mountain ranges look alike
across vast oceans.