Download Cosmology Astronomy 1 — Elementary Astronomy LA Mission College Spring F2015

Cosmology
Astronomy 1 — Elementary Astronomy
LA Mission College
Spring F2015
Quotes & Cartoon of the Day
“There is a theory which states that
if ever anyone discovers exactly
what the Universe is for and why it is
here, it will instantly disappear and
be replaced by something even
more bizarre and inexplicable.
There is another theory which
states that this has already
happened."
— Douglas Adams
“Our sun is one of 100 billion stars in
our galaxy. Our galaxy is one of
billions of galaxies populating the
universe. It would be the height of
presumption to think that we are the
only living things in that enormous
immensity.”
— Wernher von Braun
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Announcements
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Midterm (maybe) graded…
Final 12/15 at 10-12 AM!
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Comprehensive
Will review Thursday
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Last Class
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Midterm
Before that
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Our Galaxy, the Milky Way
Hubble’s Law (LT Expansion) Need to debrief
Cosmology (time permitting)
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
This Class
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Debrief Midterm
Debrief LT
Cosmology & Fate of the Universe
Exoplanets (time permitting)
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Debrief Midterm
Astronomy 1 — Elementary Astronomy
LA Mission College
Spring F2015
Debrief LT -- “Making Sense of
the Universe and Expansion”
Lecture Tutorial pp 151-154
Astronomy 1 — Elementary Astronomy
LA Mission College
Spring F2015
Which of the following statements about the
observable universe is correct?
A. It includes all galaxies in the universe.
B. It is the same size for all possible vantage points.
C. It extends to the edge of the universe.
D. It includes the same region of space for all
possible vantage points.
E. More than one of the above choices is correct.
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Let’s Practice
In the “balloon analogy,” what aspect of the real
universe does the inside of the balloon represent?
A. space and time
B. the center of the universe
C. nothing
D. where the universe used to exist
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
In the “raisin-bread analogy,” what aspect of the real
universe does the surface of the loaf represent?
A. the size of the universe
B. the edge of the universe
C. nothing
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
IT ALL STARTED WITH…
Expanding Universe
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General Relativity
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The Cosmological Principle
implies....
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
It all started with a Big Bang
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Editorial Note
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The Bearnaked Ladies got a lot right except for making
all the elements...
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But very smart people had the same wrong idea for a
long time
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Only H and He (a little Li) are made by Big Bang
nucelosynthesis.
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
The Big Bang
Astronomy 1 — Elementary Astronomy
LA Mission College
Spring F2015
What Was the Big Bang
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NOT an explosion
NOT something that happened in a single place
“It is better thought of as the simultaneous appearance
of space everywhere in the universe. That region of
space that is within our present horizon was indeed no
bigger than a point in the past. Nevertheless, if all of
space both inside and outside our horizon is infinite
now, it was born infinite.”*
* WMAP Cosmology 101 Website
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
The Father of the Big Bang
http://exlaodicea.files.wordpress.com/2008/01/lemaitre-einstein.jpg
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Belgian physicist & Catholic priest Georges
Lemaitre
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Also predicted theoretically Hubble’s Law
“Rather than expanding into pre-existing space, The
Big Bang created space. It has been expanding ever
since.”
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Energy and Mass are Interchangeable
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Einstein realized that matter and energy are really the
same thing
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E=mc2
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Mass can be converted to energy
Energy can also be converted to mass
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In the hot, compact early universe, matter could not
exist, only energy
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Energy later became matter...
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
From “the History of Everything” by the Barenaked
Ladies
“Our whole universe was in a hot dense state...”
Accurate
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Let’s Practice
Compared to now, how would you best describe the
early universe?
A. hotter and less dense
B. colder and less dense
C. hotter and more dense
D. colder and more dense
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
EVIDENCE FOR THE BIG BANG
3 Main Observations Support the Big Bang
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The Expansion of the Universe
The abundance of H, He & Li in the early universe
The Cosmic Microwave Background Radiation
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
What is the CMB?
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The Big Bang theory predicts that the early universe was
very hot
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Implies that the early universe should be filled with
radiation from the heat left over from the Big Bang
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This is the CMB (Cosmic Microwave Background)
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Discovery of CMB
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Imagine you built a spiffy new piece of equipment to
measure radio emission from communications
satellites...
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...and you kept getting this irritating noise with
wavelength 7.35 cm from every direction!
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Discovery of CMB
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What would you do?
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Check the equipment for errors?
remove the pigeons nesting in your radio antenna?
????
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Discovery of CMB
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Arno Penzias and Robert Woodrow Wilson, at Bell
Labs in 1964
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At that same time a group of astrophysicists at Princeton
were preparing to search for microwave radiation from
the early universe.
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eventually concluded the faint signal was real & came from
outside the galaxy
A friend told Penzias about their paper
Penzias & Wilson realized what they had discovered
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and were awarded the Nobel Prize in Physics in 1978
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
The CMB today
fluctuations
only one part in 100,000
http://www.astro.ubc.ca/people/scott/cmb_intro.html
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Very cold
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~2.725 K (2.725° above absolute zero)
can be detected everywhere we look.
astonishingly uniform in every direction
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tiny fluctuations are of extreme interest to cosmologists
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
The Blackbody Spectrum that got a Standing Ovation
Photo: P. Izzo
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John Mather presented this the January 1990 meeting
of the American Astronomical Society Meeting.
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Based on the first 9 minutes of data from COBE
(COsmic Background Explorer)
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John Mather and George Smoot were awarded the
Nobel Prize in Physics in 2006.
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
TIMING OF THE BIG BANG
When was the Big Bang?
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Until recently, astronomers estimated that the Big Bang
occurred between 12 and 14 billion years ago.
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Solar System ~ 4.5 billion years old
Humans ~ few million years.
Astronomers estimate the age of the universe in two
ways:
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by looking for the oldest stars
by measuring the rate of expansion of the universe and
extrapolating back to the Big Bang
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
When was the Big Bang?
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We Estimate the age of the universe in two ways:
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extrapolating back to the Big Bang
Oldest globular clusters contain only stars less than 0.7
solar masses.
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looking for oldest stars
11-18 billion years old (15.5 ± 3.5 billion yrs)
Working backward
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gives age 13.7 ± 0.13 billion years!
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
THE HISTORY OF THE UNIVERSE
The whole universe was in a hot, dense
state...
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
From “the History of Everything” by the Barenaked
Ladies
“...Then nearly fourteen billion years ago expansion
started
Wait!”
Accurate
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
From “the History of Everything” by the Barenaked
Ladies
“...The earth began to cool
The autotrophs began to drool
Neanderthals developed tools
We built a wall
We built the pyramids
Math, science, history
Unraveling the mystery
That all started with the Big Bang
Bang!”
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
FORMATION OF “STRUCTURE”
Formation of Structure
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The universe starts out uniform (homogenous and
isotropic) and somehow it becomes “stringy” and “clumpy”.
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First stars and galaxies at about 2 million years
Process not yet well understood
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
From “the History of Everything” by the Barenaked
Ladies
“... Since the dawn of man is really not that long
As every galaxy was formed in less time than it takes to
sing this song”
Partially accurate. The seeds of structure... dark
matter organizing the universe… occurred at about
100s. The actual galaxies appeared much later.
“A fraction of a second and the elements were made”
Inaccurate. H & He (a little Li) very quickly at few
second. Everything else as massive stars fused
elements up to iron in their core and then went
supernova.
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
From “the History of Everything” by the Barenaked
Ladies
“... The bipeds stood up straight
The dinosaurs all met their fate
They tried to leap but they were late
And they all died
They froze their asses off
The oceans and Pangea
See ya, wouldn't wanna be ya
Set in motion by the same Big Bang
It all started with the big Bang!”
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
THE ROLE OF DARK MATTER
AND DARK ENERGY
What is the Universe Made of?
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Current theory
suggests that 95% of
the universe is Dark
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Credit: NASA / WMAP Science Team
70% Dark Energy
25% Dark Matter
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Dark Matter
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Dark matter is typically detected by its gravitational
effects on matter we can “see”
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Baryonic dark matter is “normal” matter we just haven’t
detected (too cold/faint)
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Not likely to account for all the “missing matter”
Nonbaryonic dark matter is the exotic stuff
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One of the primary motivations for building “supercolliders"
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Dark Energy
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In 1998 we discovered that the Universe is actually
speeding up its expansion
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total shock to astronomers.
Discovered by observing Type Ia supernovae
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Surveys determined they were fainter than their redshiftdistance indicated
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Dark Energy
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"dark energy" refers to the fact that something must be
causing space to accelerate in its expansion.
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We don’t know what it is. At all.
Some astronomers identify dark energy with Einstein's
Cosmological Constant.
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Here we are
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Just when you started to think you knew what was in the
Universe....
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We think 70% of it is made out of something that we
have no idea what it is!
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The ultimate fate of the Universe depends on this
unknown stuff
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
THE FATE OF THE UNIVERSE
Big Crunch, Big Freeze, Big Rip?
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Mass (or mass and energy) determine the scenario.
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Fate of the Universe
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The most current
relevant results,
support the “Big
Chill” scenario
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from WMAP (Wilkinson
Microwave Anisotropy
Probe)
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Other scenarios,
however, are not
conclusively ruled out.
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Stay Tuned
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
From “the History of Everything” by the Barenaked
Ladies
“... It's expanding ever outward, but one day
It will cause the stars to go the other way
Collapsing ever inward,
We won't be here,
It won't be heard
Our best and brightest figure that it'll make an even bigger
Bang!”
Not ruled out! However, not what the best current data
suggests. It all depends on dark energy & dark matter.
Know how to defend it!
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
From “the History of Everything” by the Barenaked
Ladies
“... Austrelopithicus would really have been sick of us
Debating how we're here
They're catching deer
We're catching viruses
Religion or astronomy
Descartes, Deuteronomy
It all started with the Big Bang
Music and mythology
Einstein and astrology...”
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
From “the History of Everything” by the Barenaked
Ladies
“... It all started with the big bang
It all started with the big
Bang!”
Yep
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Let’s Practice
What is the ultimate fate of the Universe?
A. To expand forever and grow colder and colder.
B. To remain exactly as it is today.
C. To stop expanding, turn around, and eventually
become a point again in the “Big Crunch”.
D. We don’t really know.
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
What do observations of the structure and content of
the universe suggest will be the ultimate fate of the
Universe?
A. To expand forever and grow colder and colder.
B. To remain exactly as it is today.
C. To stop expanding, turn around, and eventually
become a point again in the “Big Crunch”.
D. We don’t really know.
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Most of the Universe is made up of which of the
following?
A. Visible matter
B. Energy
C. Baryonic dark matter
D. Non-baryonic dark matter
E. Dark energy
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Dark energy is _______.
A. what keeps the Cosmic Microwave Background
warm
B. a name for the unknown cause of the Universe’s
present increase in its rate of expansion
C. what you get when you plug dark matter into E=mc2
D. the cosmological equivalent of dragons
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Other Worlds
Extrasolar planets and systems
Astronomy 1 — Elementary Astronomy
LA Mission College
Spring F2015
There are a lot of planets out there!
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1879-1935 extrasolar
planets around 1225
stars
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471-484 multiple planet
systems
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http://exoplanet.eu/
catalog/
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Simple flat-table list
4696 Kepler
candidates!
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
There are a lot of planets out there!
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298 are very large
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Radius larger than 6x Earth
150 are small
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Radius less than 1.25 x Earth
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
DETECTION METHODS
How do we find them?
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Direct imaging
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Radial Velocity (RV)
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Planet blocks light from parent star
Gravitational microlensing
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Planet induces doppler shift in parent star
Transit photometry
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Rare
Planet causes background object to brighten
Astrometry
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Planet causes parent star to shift position periodically
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Exoplanet Image
Beta Pictoris b (bright spot) orbiting its star (center)
Credit: Bruce Macintosh et al.
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Beta Pictoris about
63.5 light years from
Earth
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Beta Pic b (planet)
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dist from Beta Pic about
9x dist Earth from Sun
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VERY large, ~ 1.6x
radius of Jupiter
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
RV Animation
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Transit Method Animation
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
KEPLER
Kepler
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Capable of finding
earth-sized planets in
the habitable zone of
nearby stars
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Transit method
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Now in modified
extended mission K2
(has lost 2 reaction
wheels)
962 confirmed planets
to date
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Kepler Overview
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
MOST EARTHLIKE PLANET “EARTH 2.0”
KEPLER 452B
Transit Graph
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Artist’s Concept
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Kepler 452b
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Kepler 186-f came first
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Kepler 186f discovered April 2014 was first Earth-size
planet in Habitable zone.
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Composition not as clearly confirmed as rocky
Orbits very close to a dim M-type Star
about 500 ly distant
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
“Earth 2.0” Kepler 452b
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Discovered July 2015 (press con 7/23)
Orbits G-type Star
about 1400 ly distant
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
WRAP-UP
Topic for Next Class
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The Big Bang & the fate of the universe
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Reading Assignment
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Astro: 11
Astropedia:17
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015
Homework
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None at this time
Astronomy 1 - Elementary Astronomy
LA Mission College
Levine F2015