Download Sunday March 5th

Week 4 The Large Scale
Universe
Galaxies, Cosmology,
The Theory of Everything
Our Galaxy – from the Inside
In visible light
And in IR
Our Galaxy in History
Discovery
– 200 years ago
astronomers assumed
stars were evenly
distributed through
space!
– 100 years ago – we
were the center of a
disk of stars
Our Galaxy

Variable stars were the trick
– RR Lyra and Cephid = Henrietta Leavitt
 Instability Strip on H-R Diagram upper right
 Period Luminosity Relationship right
 Hubble in 1923 found Cephids in other galaxies =
same distance calculations but on an intergalactic
scale!
Our Galaxy pg 542-543
– Galactic Structure
right top



A Center (nuclear
bulge) right bottom
Disk
Halo below
Open clusters vs.
Globular Clusters
Galactic Structure
 Mass of a Galaxy
 Not only is the overall mass important,
but the distribution of mass
 Disk orbits and Halo orbits lower left
Dark Matter
Keplerian motion is expected
– Falls apart at the outer edge!
– DARK MATTER
– A form of matter that does not react to E-M forces, or
the Strong or Weak nuclear forces… only gravity





A Halo around the galaxy
Extends as far as 7X the visible radius of the galaxy
Contains 10-100X the mass of the visible galaxy in it!
But we can see through it!
Particles? Another force? A problem here and elsewhere.
Dark Matter and Galaxies
Galactic Structure
 Formation
– Similar to the Solar System
Theory in principle right
– Age
From oldest open clusters = 7
billion years
From globular clusters
(Hipparcos observations) = 11
billion years
Stars in the disk have metals
(things heavier than Hydrogen
and Helium), stars in the halo are
almost entirely Hydrogen and
Helium)
Formation of Galaxies
Dark Matter a factor as well?
Galactic Arms
We are in the Orion-Cygnus Arm
– The next arm out is centered in Perseus (near
Cassiopeia), the center of the galaxy is in
Sagittarius
– Radio observations give us much of this
structure (since light can’t get through the dust)
– The arms are NOT solid objects held together
by some force
More Galactic Structure
Spiral Arms make up the outer reaches of our
Galaxy
What makes arms?
– Best theory = the Density Wave Theory- they
are like sound waves/shock waves traveling
through the disk
– O and B stars live their short lives before the
wave passes (so we see the brightest stars
– BUT what starts the waves? How do you get
branches? = Unknown.
More Galactic Structure
 The Nucleus:
–
–
–
–
Core region about as big as the full moon in our sky
Massive Black Hole = 2.7 million star mass!!
Stars 860 AU away circle the core in 16 years!!!
Event Horizon (Schwarzschild Radius) = 13X larger
than our sun in size.
In the Core
The Core of the Galaxy
Galaxies in General
 Arms and Stars= TYPES of Galaxies
–
–
–
–
Elliptical Galaxies left
Spiral Galaxies + Barred Spirals center
Irregular Galaxies lower right
NEW! Dark Matter finding!!
Spiral Galaxy Zoo Members
Elliptical
Galaxies
And Irregular Galaxies
An old idea
 Edwin Hubble = Evolution Diagram
– E0 (round) to E7 (flat) elliptical
– S0 (part elliptical and part spiral) , Sa to Sc – looser spiral
– SBa to SBc lower barred spiral
– Irr Irregular
A better structure- by age alone
Galactic
Winds –
Young
Galaxies
?
More on this
later…
Galaxies in General
Distances to the Galaxies
– Light years and parsecs are too small now – We’ll use
megaparsec (Mpc)
– One Mpc = 3.26 million light years or 2x1019 miles
– Cepheids can be seen for 200 Mpc
(.6 billion light years = the universe is about
14 billion light years in radius)
Cepheid Variables
Far Out Galaxies
– Beyond this we have to use the overall
brightness of galaxies themselves (similar
shape and detail)
– Supernova can help too (but are rare)
– LOOK BACK TIME (Moon = 1.3 seconds,
Sun= 8 minutes, Alpha Centauri = 4 years,
Andromeda Galaxy 2 million years, The ‘edge’
of the universe = 13.7 billion years)
Out =
back in
time
Looking Out at Galaxies

The most distant galaxies visible = 3000 Mpc
(10 billion light years)
 The Hubble Law
– Vr=Hd (Vr= velocity of galaxy away from us, d=
distance in Mpc, H = Hubble Constant
(km/sec/Mpc)
– Newest results put H near 70-80 km/sec/Mpc

71 ± .4 km/sec/Mpc EVEN MORE RECENT from
WMAP
Hubble Velocity-Distance
Relationship
The Ladder of Distances
Looking Out at Galaxies
OTHER
CRITTERS
– Colliding Galaxies
Active Galactic Nuclei
– Galaxies with Active Nuclei – wind again
Pump out radio and X-ray radiation and jets (from
the central Black Hole)
– Comes from Collisions = newest theory
Quasars
– Quasars
Special active nuclei cores near the
beginning of the universe (the furthest
things visible in the universe)
Moving away from us at a good
fraction of the speed of light!!!
Massive Black Holes
Gravitational lens (Einstein)
A good
quasar!
Jets are
common
The discovery of quasars…
Incredible Red Shift!!
A distant
quasar,
core outshines it’s
disturbed
galactic
arms
Two lobes (in radio light)
ejected from a galactic core
Artists
conception
of an active
galactic
nuclei
AT the core of it… massive
black holes
Artist’s Interpretation
How the massive Black Holes at the
Galactic Centers make the Jets
How do we find massive
galactic black holes?
That takes us to the edge of
stellar light. Lets look at the
universe itself!
The Structure of the Universe
The Structure of the Universe
– Clusters of Galaxies
2700 clusters within 4 billion light years
Rich galaxy clusters = >1000 galaxies
Poor galaxy clusters = < 1000 galaxies
See the Hubble Deep Sky Image… next two frames
But does it go on forever?
Is the universe infinite as
Einstein assumed?
The Structure of the Universe
– Olber’s paradox - not an infinite universe
The Universe as a Whole
– Assumptions of cosmology
Homogeneity = (distribution)
Isotropy = (looks the same)
Universality = (laws)
Cosmological Principle = (other observers would
see the same stuff)
Expansion
Einstein and the geometry of Space –
Time
– The universe is expanding (Hubble et.al.)
But not INTO anything lower left
 There is more empty space all the time
(dense regions not expanding)
 Red Shift from expansion right
 Space time is Curved – but how?

Universal
Geometry
– Finite but unbounded – like a GLOBE = favorite OUT
– Infinite and unbounded – like a piece of paper - forever
So is there an edge?
Arno Penzias and Robert Wilson – Bell
Laboratories around 1965
 Detected the
Cosmic Background
Radiation

Cosmology- The Big Bang
– The Big Bang – why is it the
best theory?
Primordial Background
Radiation
– Echo or remains of early HIGH
DENSITY time
– 2.7 Degree glow (remember
Weins Law = peak radiation and
temperature) No emission lines
since it was a compressed
universe. Just temperature
Present expansion and
distribution of material COBE
Darkness between galaxies
(Olber)
WMAP map
NASA/WMAP Science Team
Average temp = 2.725K (-455F) – Red = 0.0002 degrees warmer than
the blue areas)
NASA/WMAP Science Team
Old vs.
New
NASA/WMAP Science Team
What
WMAP
sees
Breaking News

Newest findings…
The most important PPT slide in 100 years

WMAP Results
– Space all across the universe is flat, parallel lines never meet.
–
–
–
–
–
–
–
The inflation theory underlying the Big Bang is correct. The
universe continues infinitely far beyond our horizon.
The universe is a mixture of 4.41 ± 0.3% normal baryonic matter,
21.4 ± 2.7% dark matter, 74.2 ± 3% dark energy (anti-gravity
like force)
Dark matter is ‘cold’ not ‘hot’ or ‘warm’. Neutrino limits set.
The universe is 13.73 ±0.12 billion years old (best yet)
Hubble Constant = 70.1 ±1.3 km/sec/mpc
Maximum “Z” (CBR) = 10.8 ±1.4
First stars turned on only 100-400 million years after big bang
The large scale filaments of galaxies are frozen remains of the
subatomic sized universe = quantum fluctuations
Make-up of the Universe
What does
a Flat
Universe
Mean?
What does the ant
see on a surface that
is really a larger and
larger sphere?
What if the sphere is
nearly infinite in
size?
Cosmology – The Big Bang
Before the Big Bang?
– Another universe – bounce?
– Our universe? (Finite and unbounded in time?)
– Depends on your favorite theory!
The History of the Big Bang
– ‘Nothing’ at first – then it begins
– 1/10,000,000 ths of a second = 1 trillion (1012)K , 5x1013
g/cm3)
– No matter- just energy (light)
– More matter than anti-matter made by a small margin (1
billion to one)
– 4 seconds = all protons and neutrons made (cooled out)
– 2 minutes = deuterium could form
– Nuclear reactions (like in stars) formed helium
– 30 minutes nuclear reactions ended (too cool now)
– 1 million years –up to here a bright radiation dominated
universe
– Atoms formed – electrons could be caught T= 3000K then
TRANSPARENT!
What COBE/WMAP see, the 2.725K background radiation
glow.
Cosmology in the End
– The end of the universe?
– Critical Density
– 4x10-20 g/cm3
Options
– Closed universe (Big Crunch someday)
– Open Universe (Heat Death) favored
– Oscillating Universe (bouncing
re-creation)
– More on this later…
The makeup of the universe
– Dark Matter (2001 vs. 2005)
 Apparently 90-99% of the universe is Dark Matter
(Now 21.4 ±2.7%)
 The visible universe is only the tip of the iceberg!
(Now 4.41 ±0.3%)
 Dark Energy (Now the remaining 74.2% ±3%)
 MACHO’s – massive Compact Halo Objects
(Elliptical vs. Spiral)
 Gravitational lensing again
A Quantum Universe – Refinements of the Big Bang
Theory
 Big Bang problems
– Flatness problem – we are balanced on the open/closed boundary
– Isotropy- background radiation is too smooth 1 part in 1000
perfect!
• The horizon problem- same temperature but no connection
 A Solution = inflationary period – makes it flat
The Grand Unification Theory
– The Grand Unification
Theory
Another way to look at it…
Zero Point Energy and
Freezing Forces
In cosmology, the vacuum energy
is taken to be the origin of the
cosmological constant (dark
energy(?)). Experimentally, the
zero-point energy of the vacuum
leads directly to the Casimir
effect, and is directly observable
in nanoscale devices.
Putting it
all
together
What is the CBR glow?

It is the place back in time that we see the
moment the universe became transparent.
 It was a solid then too thick or opaque
before then… we can’t look farther.
What else does a GUT help?

Einstein's General
Relativity and
Quantum Mechanics
Don’t Play Nicely
in Black Holes
 The
singularity is the problem
Re-fresh of Einstein and
Gravity
Different Gravitational
Strengths
GUTs

Einstein et. al.





All velocities are relative
(Special Theory)
Space and time are both aspects of the
same thing Acceleration pull and
gravitational pull are indistinguishable
(General Theory)
Energy and Matter are the same (E=mc2)
LATER- Space-time curvature is energy
(Superstring theory)
General Relativity and Quantum
Mechanics DON’T MIX! Within the atom
either. Or do they?
Super Duper Strings
– Superstring theory
 Four forces
–
–
–
–

Strong = Gluon
Electromagnetic = Photon
Weak = Weak gauge boson
Gravity = Graviton
3 Families of 4 particles each
– Electron, Electron neutrino, Up-quark, Downquark
– Muon, Muon neutrino, Charm Quark, Strange
Quark
– Tau, Tau neutrino, Top Quark, Bottom Quark
Grand Unification II

No room in the inn
– Strings make properties of the particles via their
–
–
–
–
vibrations, but not enough room in 3 or 4 dimensions
More dimensions allow us to link the forces
10 needed (3 space, 1 time, 6 curled up space) to go
to gravity
Curled up below the sub-atomic scale previous page
Calabi-Yau Shapes = 10,000’s which one?
next page
Curled up higher dimensions


All these force particles and particles
are made up of strings : 10
dimensions curled up
And this solves the infinities at the
smallest scales… Relativity and
Quantum Mechanics can merge
M-Theory

The attempt to unify everything has lead down
five roads so far…
 M-Theory – adds 1 more dimension = 11
– Add one more dimension and you have a linking of the
major theories! NOT FINISHED YET! 10-20 or 100
years???
– The blind men and the elephant…
Other Uses for Strings?
Cosmic Strings – can cause gravitational
lensing, can account for missing mass in
universe
 Can create time travel
 Black Holes and Time Travel

Gravitational Lensing
The first great test of
Einstein’s Theory
Lensing
Einstein Ring
There is just
one galaxy or
quasar in the
background
Einstein Cross
Time
Strings
and Time
A nod to branes

Recent work (2003+) has now bounded the higher
dimensions by membranes (branes) that.
 p-branes (fill in your own # of dimensions for “p”)
 We might be in a 4-D universe
(3 space + 1 time) that is next to another
4-D universe separated by a 5th dimension
 The other 4-D universe is a ‘shadow’ universe where
gravity is rooted
Parallel Universes

There are many flavors:
The Other
You’s


Implications
of an infinite
flat universe
10115
10 meters
Quantum Weirdness

One way that the math in the quantum world
works well is if you add up ALL the POSSIBLE
paths of a particle and see how they interact.

So there ‘might’ be a universe for every alternate
possibility – a universe where you are following
out every choice you ever made and could have
made.
Freaky Interference again?

This is another way to explain how particles
can form this interference pattern, even if
only one is let through the two slits per hour
for weeks on end!
Another possible Big Bang

This leads us to the possibility that the big bang
wasn’t a tiny dot that expanded.
 The universe might have thinned out and thinned
out until a ‘parallel’ universe just fractions of an
inch away could close and touch our universe.
 This would have filled the universe with a
tremendous amount of energy that then would
expand away.
Just like the Big Bang! But different!
 Then end is different then – a big expansion then
another BANG!  Next Slide!
Here comes the brane

Link
To
Animation
Dark Energy and the END!

The expansion rate of the universe is
unsteady…and is accelerating.

Eventually it will dominate the universe…
everything will be torn apart to photons… then
start over again.

UPDATE: Newest observations hint that normal
expansion, not the ‘tearing apart of even atoms’,
will occur.
Another version of reality…
Information




is King
Closely realted to:
Information theory
Quantum Gravity
Loop Quantum Gravity
Subtitled:
All the uses for a simple looking equation:
S= k log w
Redundancy

We deal in information
 The information we work with is filled with
redundancy.
– Language (think of static on the radio)
– Addresses (zip code + 4)
– Internet protocols (duplex)
– Pictures/vision (can make out images through
fog/static/snow/tall grass)
– Code breaking (look for ‘rules’ in language)
An example of a simple law of
physics

A Heat Engine
 Law of thermodynamics
 (Entropy S=k log W )
The 3 Laws of
Thermodynamics
1st law= Energy can’t be created or destroyed =
you can’t win
 2nd law= The universe is moving towards an
equilibrium = you can’t break even (no perpetual
motion machines)
 3rd law = You can’t cool anything to absolute zero
= there is always some information in any system
– you can’t go broke.

Entropy
Entropy

The number of ways you can organize things in a
space.
 Bell curves!!

These show up in–
–
–
–
Grades
People heights
All over the natural world
MUCH of the world is actually
a STASTISTICAL phenomena
Bell Laboratories again

Claude Shannon –
– Asked: How much information can you
squeeze into a telephone line? What is the
max?
– Think of Paul Revere = red light, green light
– 1 light, 2 bits of information (land, or sea)
– 2 lights = 4 (RR=land, RG=sea, GR=train,
GG= car)
Claude and beyond


3 lights (RRR = land,
RRG= sea, RGR=train, RGG = air,
GRR = hovercraft, GRG=spaceship,
GGR= teleportation, GGG = on backs of evil
angels) --- 8 bits!
He found that when you have a question with
N possible outcomes, you can answer it with only
log N bits (letters).
 Or x= log N - N= number of sounds or bits,
x=the maximum information you need to carry.
Talk talk talk





Everything done on a computer is done with
letters of 0 and 1.
Everything done in your genetic code is done with
4 letters (GCAT).
Our language = 26 letters = vast number of words!
But the maximum information you can carry is
log N, and Entropy = k log W
(k= a constant, W = the number of possible states)
Entropy again

So Entropy is really the measure of
information!
Entropy
There is only a few ways to have a perfect egg – a few
bits, but many many many ways to have a smashed egg.
Enter – Einstein

Relativity says that nothing can go faster
than the speed of light, and that the
phenomena you observe depends on your
viewpoint (more so at great speeds).

Barn and pole relativity experiment:
Close the barn door!
Answer: the view from the observer and the runner is DIFFERENT=
relative! It all comes down to the transmission of information!!!
Back to the subatomic world

Everything is quantized in the subatomic
world where bits of matter are BOTH waves
and particles (wave-particle duality –
remember?)
Superposition
a way to get wave/particle things


Schrödinger's Cat
Without info
on a subatomic
particle (or a cat),
it becomes both
or all states at
once!
 Alive AND Dead
 Observation makes
the probability cloud
collapse
Information
Again – getting an observation of the cat,
electron, nucleus, etc. collapses the
probability wave for an instant…all other
possibilities go away.
 But all those other possibilities interact with
the world! (Think of the two slit
experiment again… one photon a week =
the same pattern!!)

The power of quantum
computers

If we leave the atom or electron or photon
UNOBSERVED, then it remains in superposition
(all possible states at once).
 Instead of an 8 bit computer, 16 bit, 32 bit, 64 bit,
you get every combination in-between (all partial
bits as well).
 Can solve math problems that would take millions
of years today in minutes. All calculations are
performed at once!
Back to the Universe now…

Remember the maximum amount of information
you can transmit (contain in an area) is = to its
entropy.
 BUT Relativity and Quantum mechanics don’t get
along (remember? Unless string theory is correct =
unproven just promising)
 Another example:
Quantum Entanglement = “spooky action at a
distance” = NO actual information transmitted!!
 Most of reality (that fact that it is even stable) is
due to entanglement of particles with each other.
Black Holes and Information

The most extreme!
– Gravity becomes massive at the quantum scale.





The surface area of a black hole = k log W
Entropy AND the maximum amount of
information you can pack into a space! And it
lives on the surface NOT the volume!
The logical end of memory compacted-ness is a
black hole.
It’s the ultimate memory stick!
But can you get the information out?
Reading Black Holes

Hawking Radiation
– Virtual particles at the edge of the Event
Horizon
– But can you get information out? Or is
information destroyed beyond the event
horizon?
– S. Hawking thinks that yes, maybe. But no one
knows how or for sure currently.
Gravity and Entropy

It can reverse it locally (as can the other
attractive forces).
But this happens over time…
So it’s time to talk about time…
Entropy and the Direction of Time
The Arrow of Time

Entropy seems to be responsible for the Direction
of Time (the past is the past and the future is the
future)
 In Relativity and Quantum Mechanics, there is no
preferred direction of time. You can reverse the
sign of ‘t’ and the meaningful things still happen.
Sometimes indistinguishable things (particles
bouncing off one another)
S=k logW

This means that the universe was very
special at the start of time.
 For us to still be running down (higher
entropy) we had to be a universe of very
LOW entropy at the start
 How did the universe get ‘wound up’ or
ordered at start?
 One possibility…
The history of the
universe pt 1
The history of the
universe pt 2
The secret is a
very very
specific, low
entropy, exact
form of initial
configuration
of
material/energy
in the sub-atom
sized nugget
that started
everything…
Back to parallel universes

So we can draw a bubble (like an event
horizon) around us… say at the edge of the
observable universe (our Hubble Bubble)
and calculate how many states you can
organize everything in (every particle in
every spot).
Information and the Universe

Information is located completely on the
surface of a black hole (area = entropy =
max information storage).
 NOT the volume.
 Just like a hologram (3-D image in a 2-D
picture) (Remember the branes?)
 So all the information in the 3-D universe
can be encoded on a 2-D bubble.
So there is a distance from us
where this exact arrangement
of particles repeats!
10115
10 meters
Plenty of room for this in an
infinite universe
The Other
You’s

Implications
of an infinite
flat universe
The Matrix Revisited

The universe ACTS like memory in a computer.
With multiple bits at every point that are ‘empty’
space or a particle (or string with that vibrations
for those phenomena) and rules that dictate how
they communicate and interact – just like a
computer program.

And there may be an infinite amount of memory
for the universe and its version to be written on!
Quantum Gravity


Gravity (and all forces) are just communication
between “points” of space (smaller than the
plank scale = 10-35m.
To be tested by a satellite looking at cosmic
rays…quantum space time fabric = a smearing
out of distant light. A smooth space time fabric
= no smearing out.
 And we’ll be looking for neutrinos from the big
bang!
Other Further Readings:

“A New Kind of Science” – Stephen Wolfram – All
reality is tiny simple programs running on sets of points of
space/time. Similar to fractal mathematics. Complexity comes
from simplicity.
 Cellular automata

Warped Passages: Unraveling the Mysteries of the
Universe's Hidden Dimensions (2005) by Lisa Randall

The Fabric of the Cosmos: Space, Time, and the Texture of
Reality (2005) and The Elegant Universe (2004) by Brian
Greene

A Brief History of Time (2005) and The Universe in a
Nutshell (2001) by Stephen Hawking
There is much more being
discovered all the time… stay
tuned!
General Public Places for this information
(In order of easier to harder to read):
•Astronomy Magazine
•Sky and Telescope Magazine
•Scientific American
•Physics Today
•Nature and Science Magazines