The Big Bang and Consequent Formation of the Solar System

1
The Big Bang and Consequent Formation of the
Solar System
Danny Dale Physics and Astronomy University of
Wyoming Find this presentation online at
faraday.uwyo.edu/ddale/teach/01_02/merav.ppt
January 29, 2002
This presentation was largely created by G. Denn
2
The basic premise

• The Universe, consisting of all space and all
  time, started for no apparent reason
  approximately 14 Gyr ago
• The hydrogen and helium condensed to eventually
  make stars within galaxies (dense regions of
  stars)
• Supernovae, and processing within red giant
  stars, created the majority of the heavier
  elements
• Ejected material recondensed to form the Sun and
  Solar System
• The earth cooled, life popped up, we started
  breathing air, etc.

3
Definitions
Cosmology The study of the Universe as a
whole Cosmogony The physical study of the
origins and evolution of the Universe Spacetime
the coordinate system of the Universe
4
What is spacetime?
Spacetime is the combination of space and time,
interrelated by the speed of light. Einstein
showed that spacetime has certain transformation
properties, and that simultaneity does not
exist-it depends upon how one clock is moving
relative to another. Your point in spacetime can
be set up as three space coordinates plus one
time coordinate Latitude 4118' N Longitude
105 15' W Altitude 7200 ft Time January 29,
2002, about 940 AM MST.
5
4-D spacetime coordinates
6
The Big Bang
The Universe started about 14 billion years ago,
in an event called the Big Bang. The Big Bang was
not an event space and time were created at that
moment. The Universe originally was infinitely
hot and dense. Since then, the Universe has
grown and cooled. What?s the evidence? a) The
recession of galaxies b) Cosmic Microwave
Background c) Hydrogen/Helium abundances in the
early Universe
7
Act I Milky Way, Galaxies,and Hubble?s Law
Galaxies contain billions of stars and huge
clouds of gas and dust. Our Sun is 25,000 light
years from the center of the Milky Way galaxy.
8
Other Galaxies
Galaxies come in three major classifications
Elliptical,
Irregular, Spiral.
9
Galactic Distribution
10
The spectrum of the Sun
11
Things that are approaching you are said to be
blueshifted, but are not necessarily blue.
Things that are receding from you are said to be
redshifted, but are not necessarily red. This is
called the Doppler Effect.
12
The Doppler effect
The ?blue? end of the spectrum is at short
wavelengths, high frequencies. When something is
?blue-shifted? its spectrum gets transformed into
one with higher frequencies. When something gets
?red-shifted? its spectrum gets transformed into
one with lower frequencies.
13
The Doppler effect works with sound waves also.
14
However, there is no sound in space! Light waves
are either blue- or red-shifted.
15
Gotta little somethin' in the oven
As raisins in an expanding raisin bread are all
moving away from each other, the galaxies are all
receding from each other in an expanding
universe.
16
Hubble?s Law
Edwin Hubble noted that almost ALL galaxies
had redshifts and NOT blueshifts. The redshift
is proportional to the distance. From the
Doppler effect, this indicates that the galaxies
are receding from Earth. The best explanation is
that the Universe is expanding.
The fit for the graph above says that for v
Ho d Ho (67 15) km/s/Mpc. Ho is known as
Hubble?s constant.
17
Act II Blackbody Radiation
Everything above absolute zero can release energy
via thermal emission. The characteristics of the
emission depend solely upon the
TEMPERATURE. Wien?s Law Hot things are bluer
than cool things.
18
(No Transcript)
19
The Universe is at about 2.7 K
20
What does the future hold?
If the Universe has enough mass then gravity will
pull it back together in a Big Crunch. If not,
then space will forever grow.
21
Flat and Curved Space
22
But we can test for it
23
What?s the curvature of space?
There are three options Flat (below) Curved
Positive (corner) Curved Negative (right)
24
Science Magazine's Breakthrough of the Year (1998)
fainter
farther
25
BOOMERanG evidence...Ballon Observations of
Millimetric Extragalactic Radiation and Geophysics
These data, which attempt to show the isotropy of
the universe, describe how ?sound? traveled
through the early universe. The conclusion is
that the universe is FLAT.
26
We think we are converging to an answer
Dark Energy Fraction
Which means it will expand to Which means that
some being somewhere else will give the same
lecture, except that it will be wearing a suit
and tie and have purple hair.
Matter Fraction
27
Act III Chemical Evolution
In the first few minutes of the Universe, some of
the elements formed. _at_ t 10-6 s The Universe
was at T 1013K and filled with high energy
gamma rays, which can form massive particles in a
process called pair production.
28
The cooling Universe
As the Universe cooled, fusion of the heavier
elements took place. The result was about 76
percent hydrogen, 24 percent helium, and traces
of Lithium, Beryllium, and Boron.
29
When did stars form?
When looking as far back as possible, we see
evidence for faint blue galaxies at a time of
about one billion years after the big bang. These
original stars were composed of the primordial
elemental abundances.
30
Processing in Supernovae
A supernova is an explosion that occurs when a
star can no longer support itself against the
force of gravity. Normally, hydrostatic
equilibrium is maintained gas pressure and
gravity find a balance. Stars convert hydrogen
into helium and other heavier elements. This
fusion process releases energy. When a star runs
out of fuel, it starts to collapse upon itself,
which releases gravitational energy. This can
either a) heat the star up so it can burn other
fuels (e.g. three helium atoms form one carbon)
or b) if the star is really out of fuel, it
collapses suddenly, releasing an incredible
amount of energy (brighter than the host
galaxy!). This explosion drives nuclei into each
other in a rapid set of reactions.
31
Collapse of the core of a Red Giant and shock
wave (that forms elements)
32
(No Transcript)
33
Molecular Clouds
After many generations of supernova processing,
the Milky Way had enough heavier elements to form
rocky planets. The Sun formed in a molecular
cloud (now long gone) similar to the next image
taken with the Hubble Space Telescope
34
A Star forming regionM16
This cloud is about 30 light-years across. The
stars are formed in the EGGs. Newly ?hatched?
stars are visible in the vicinity.
35
Current chemical abundances
36
Solar Nebula Infalling Material
37
Rotating Disk
The planets form out of the rotating disk
surrounding the protostar.
38
Beta Pictoris
Tiny interstellar dust grains serve as
condensation nuclei--platforms to which
other atoms may attach, forming larger and larger
balls of matter.
1000 AU
39
Condensation vs. Temperature
Heavier elements tend to condense at higher
temperatures than the lighter elements. This has
a ramification for the structure of the Solar
System.
40
The planets condensed at different temperatures
41
One of the planets has life
42
End of Presentation
43
Life in the Universe
Summary The Universe started about 14 billion
years ago as an infinitely hot and dense dot, and
has grown larger ever since this Big Bang is
evidenced by the recession of galaxies and the 3K
background. About a billion years after the Big
Bang, galaxies formed out of the mostly hydrogen
Universe. Stars and the subsequent explosion of
massive stars converted hydrogen into helium and
other, heavier atoms. About 5 billion years
ago, the Sun and solar system were formed out of
the material that had been processed many times
by generations of star formation and supernovae
(stellar explosions which create heavy elements).
About 3.8 billion years ago, the Earth was cool
enough to have liquid water. Blue green algae
formed and took the carbon dioxide out of the
atmosphere. Life was single-celled until 700
million years ago (about three solar orbits
around the galaxy), and it evolved in the water.
When the ozone layer formed, it blocked UV light
so land-based life could survive. Mammals are
about 200 million years old, and apes (homo
sapiens) arrived about 500,000 years ago. I
showed up 31 or so years ago, and am the acme of
evolution.
44
How to define life?
The universe may or may not be teeming with
life, but this part of it certainly is. We will
not be discussing the origins and evolution of
consciousness, only how science defines life.
Life needs a definition, and since it is
difficult to define, we'll just set up some rules
and try to adhere to them. Life A) comes in
cellular form B) has a genetic system
to reproduce C) has a metabolism
D) evolves in a generational form.
45
Life on Earth
Life on Earth contains amino acids and
nucleotides, which form proteins and nucleic
acids. The amino acids in life are left handed
only no right handed form is known, but in
theory could be produced. Life needs water and
is carbon based.
46
Origins of Life
The origins of life on Earth may (or may not)
come from one of two sources primordial soup or
extraterrestrial. Primordial Soup There is a
plethora of organic (meaning carbon based, not
pesticide free) molecules in the universe, and
many of these could be on the primordial Earth.
Given enough time, and enough heat, pressure,
electric discharges, mixing, whatever, the simple
molecules may have formed more complex ones.
Although it is unlikely that any one event
produce this, over a billion years, the number of
possibilities for events to occur is huge,
especially on the short timescales with
which chemical reactions occur (microseconds).
The Miller-Urey experiment tried to reproduce
these conditions.
47
Panspermia is not a dirty word
Panspermia the theory that life arrived on
Earth after it formed elsewhere, either within or
out of the Solar System. The spaceships were
comets and asteroids and the seeds were
freeze-dried bacteria. The Mars rock ALH84001
spurred a new interest in panspermia. As Lou
Frank once told me, "It's a plausible theory but
there are no data." However, we can test
panspermia by looking at amino acid ratios in
space, mining comets with microscopes looking for
bacteria, etc. For example, if STARDUST, a
mission to Comet Wild-2 comes back with comet
bits that have bacteria with left-handed amino
acids, that would be very good for panspermia.
48
The Acme of Evolution?
49
Geodesics the shortest paths
The shortest path between two points is said to
be a geodesic. In space-time, light travels from
A to B along geodesic paths.
50
Information travels at or below the speed of light
51
(No Transcript)
52
Travelling to the nearest star
53
Life is so precious?.