Download Big Bang Theory

Pertemuan ke-2
The big bang theory
The Origin of the Ea
its Oceans and Life
the Oceans
(Asal-usul bumi, laut dan kehidupan d
1
Course Outline
1. The Origin of the Cosmos (Universe)
a. The Galaxies and Stars
b. The Elements
2. The Sun and the Solar System
3. The Origins of the Earth
a. The Geological Time Scale
b. The Origin of the Oceans and
Atmosphere
c. The Original Continents
d. The Moon
e. Life Form in asalod
the Oceans
2
Hubble Space Telescope
asalod
3
Quintuplet Cluster
Neutron Star Magnetar
Messier
asalod
Dying Star
4
Beberapa Istilah:
• Star (bintang): ‘bola’ (sphere) masiv berupa gas pijar
(terlihat banyak di angkasa)
• Galaxy: Kumpulan bintang, debu, gas dan debu angkasa
lainnya yang berotasi dan berada bersama oleh gaya tarik
gravitasi.
• Universe atau cosmos (cakrawala): kumpulan galaxy.
Kira2 terdapat 100 juta galaxy yang teramati dg teleskop
kita.
• Planet berada satu sistem dengan bintang dan bergerak
mengitarinya
• Satelit, benda angkasa yang mengelilingi planet, mis.
Bulan.
• 1 Tahun Cahaya: Kec. asalod
cahaya (~3.105 km/s) x 1 tahun5
12
Galaxy Milky Way
• Galaxy dimana tata surya kita berada)
• diameter cakram: 100,000 tahun cahaya (TC); tebal cakram
10,000-15,000 TC
• Tata surya beserta ke-9 planetnya berada sekitar 2/3 dari sisi
luar Galaxy ini.
• Tata surya mengikuti pergerakan Galaxy MW dengan kec. ~
280 km/s
• di dalam Galaxy MW terdapat ~1011 bintang, yg mana puluhan
juta binang itu memiliki planet dan makhluknya.
asalod
6
Tata Surya
(Solar System)
a. Ukuran relatif planet dan surya
a. Orbit planet dari Tata Surya
asalod
• 9 planet
• Terdekat: Merkurius
•Terjauh: Pluto
Planet yang
terdekat dgn
mthari lebih kecil
Karena emisi
partikel dari
mthari yg
terionisasi dan
pemanasan
internal planet itu
7
sendiri
Dengan mengamati energi cahaya yang
memancar dari galaxy, astronomer mampu
menentukan bahwa hampir semua galaxy
sedang menjauhi satu sama lainnya, pada
kecepatan ~240,000 km/s (3/4 kec cahaya !).
Saling menjauhnya galaxy 2 tersebut diduga
sebagai serpihan2 hasil dari suatu ledakan,
yang berasal dari satu massa yang sama. Jika
hal ini sebagai kenyataan, waktu yang
diperlukan dari ledakan tsb sampai keadaan
saat ini adalah ~15 milyar tahun.
asalod
Big Bang Theory
8
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.
asalod
1 billion=109
9
Dasar Utama
• Energi cahaya yang hasil radiasi galaxi,
makin jauh makin rendah energi (shifting
spektrum)
• Galaxi saling menjauhi karena ada
ledakan
• Apa semua pernah berkumpul, tidak
pasti?
• Waktu untuk sampai posisi sekarang ~15
miliar thn
asalod
10
Timeline of the Big Bang
asalod
11
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 1940’s
asalod
12
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 nucleo-synthesis.
Within just one
day’s 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
asalod
universe.
Heavier elements account
for only about 0.1% of all
the elements in the
13
universe.
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 asalod
Radiation predicted by14
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.
15
asalod
16
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
asalod
17
asalod
18
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,
asalod
19
and heavier elements.
Supernovas
• When all of a large star’s 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.
asalod
20
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.
asalod
21
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.
asalod
22
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.
asalod
23
Differentiation of the Earth’s Interior
• The earth’s 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
asalod
into the crust.
24
The Geologic Time
Scale
• Scientists have detailed
the Earth’s 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.
asalod
25
asalod
26
asalod
27
•
The Early
The atmosphere began
to form about 4.4 billion years ago
Atmosphere
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
earth’s surface
also released
quantities of
ammonia,
methane, and
water vapor into
the atmosphere.
asalod
28
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.
asalod
29
• Suns energy stripped away 1st atmosphere
•
2nd atmosphere formed from volcanic out
gassing
• Primitive atmosphere: CO2, water vapor, lesser
atms of CO, N2, H2, HCl, and traces of NH3 and
CH4 (3.5 billion year ago)
asalod
30
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
again.of heavy rains
• fell
A period
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
asalod
ocean almost two miles 31
Formation of Earth’s Oc
• Off gassing of water
vapor from volcano
• Condensation
• Rain
asalod
32
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 (20–70 km), and typically
composed of lighter, granitic rock distilled from the repeated
recycling of mantle material and oceanic crust (a process
in the nextcrust
lesson).
• discussed
The first continental
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.
asalod
33
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.
asalod
34
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 Moon’s
origin is the giant impact
hypothesis.
At the time Earth formed, other smaller
planetary bodies were also growing
nearby.
One of these bodies, about 1/3 to
1/2 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. asalod
35
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
planet’s rotational axis that
produces the seasons.
• Without the Moon, Earth
might experience the
extreme and hostile
fluctuations in weather and
climate observed on Mars.
asalod
36
Origin of life
• Life began~ 3.5 billion-year-ago (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
asalod
37
Stage 2: joining of small molecules
(monomers) into large molecules
asalod
38
Stage 3: origin of self-replicating
molecules that eventually made
inheritance possible
asalod
39
Stage 4: packaging these molecules into
pre-cells, droplets of molecules
with membranes that maintained
an internal chemistry
asalod
40
Thomas Huxley- Search for origin of life
Bathybiasheckalii- primordial ooze (sedimen yg
lunak)
Wyville Thompson: HMS Challenger (18721876) found it was actually diatomacous ooze
reacting with seawater and ethyl alcohol
Also, disproved Forbes’ Azoic Theory (18681870)
asalod
41
Miller & Urey (1953)- mixed water vapor, NH3,
CH4, H2
+ electric spark amino acids and other organic
compounds Synthesis of Organic Molecules
electrodes
Methane,
ammonia, and
hydrogen added
CH4
NH3
H2
water vapor
spark
condenser
boiling water
water containing
organic compounds
42
Produced:
•
•
•
•
20 amino acids
Several sugars
Lipids
Purine and pyrimidine bases (found in
DNA, RNA & ATP)
asalod
43
chemosynthetic bacteria (extremophiles)
Chemosynthesis:
02 + 4H2S + C02
CH20 + 4S +3H20
Stromatolites (bacteria &cyanobacteria)
Oldest fossils found in western Australia and southern Africa
~ 3.5 bya
Photosynthesis:
6H2O + 6CO2 + nutrients + light energy
asalod
C6H12O6 + 6O2
44
mostly cyano
Stromatolites from Shark’s Bay Australia
asalod
45
asalod
46
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.
asalod
47
Evidences in support of this
theory
• In 1969, a meteorite landed in Australia that was
12% water and contained traces of 92 amino
acids.
• 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.
asalod
48
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
asalod
49
asalod
Photograph from National Geographic magazine
50
Deep-sea Vents
• Their discovery in late 1970’s 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.
asalod
51
Exploring the deep ocean floor
View of the first hightemperature vent
(380°C) ever seen by
scientists during a dive
of the deep-sea
submersible Alvin in
1979.
Such geothermal
vents are called
smokers.
asalod
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 RISE52
expedition
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
53
colonize widely separated vent systems.
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.)
54
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
(H2S) gas
released from the
vents, and live
inside hard, shelllike protective
tubes that attach
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!
55
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
H2S, 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
56
BIOCHEMISTRY AT THE VENTS
• H 2S
Released
from
vents
Oxidation by
bacteria
Energy released helps in fixing
CO2 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 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.
57
So, ever imagined a life out of toxic Hydrogen Sulphide
Chemical of Life - Ammonia, Produced at
Vents
• Hydrothermal vents were the most likely site for NH3
production where inorganic sulphides acted as catalyst.
N2 +NO2 +N03
Presumed to be
present in ancient sea
FeO
46% yield 15 min
FeS, 500oC
Powdered
Basalt.
20% yield
89% yield, 15
min
NH3
Stable upto 800oC
58
RESULTS
• Since NH3 cannot survive at temperature above
800oC indicates that nitrogen would have been
present only as N2 during early phase of earth’s
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.
asalod
59
asalod
62
asalod
63
asalod
64