The Beginning

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The Beginning End of the Universe
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Happy Earth Day!
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Words of Wisdom and Warning
The first principle is that you must not fool
yourself - and you are the easiest person to
fool. Richard Feynman If people do not believe
that mathematics is simple, it is only because
they do not realize how complicated life is. 
John Louis von Neumann As an adolescent I
aspired to lasting fame, I craved factual
certainty, and I thirsted for a meaningful vision
of human lifeso I became a scientist. This is
like becoming an archbishop so you can meet
girls. M. Cartmill

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The Beginning
General Relativity
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Alexander Friedman
General Relativity
No static solutions In particular an expanding
universe (Einstein knew this as well, Friedmans
expanding universe solution is the one we
need.) George Gamow was a student of his we
will meet him later.
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That shouldnt happen
General Relativity
And now for the right value of lambda (the
cosmological constant) it does not
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Edwin Hubble
Coached HS basketball, member of Kentucky Bar
Association, Major in the US Army during WWI Jan
1 1925, Milky Way is not the only galaxy (Cepheid
Variables) Red shift of galaxies changes with
distance(more on this in a minute) The universe
is not static!!!
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Oops
General Relativity
The cosmological constant was the biggest
blunder of my career. (It is not more on this
later!)
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Galactic Red shift...
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Velocity-Distance Relation
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So what?

• The observable universe is bigger today than it
  was yesterday!
• So yesterday it must have been smaller.
• A week ago even smaller...
• Imagine a movie of the Universes lifetime
  running in reverse, continually getting smaller
  and smaller

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So going far into the past...

• Must have been really small a long time ago...

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Georges LeMaitre
Expanding universe solution to GR, similar to
Friedmann Worked to show the expanding universe
within Einsteins GR gave the right red shifts A
moment of creation, must have occurred at the
beginning (Cosmic Egg, Primeval Atom)
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Other possibilities emerge

• 1. The Milne model tried to keep some of the
  staticness (large scale geometry predictions
  disagree with observations also viewed as
  mathematically impossible)
• 2. Oscillatory Universe Friedman then Einstein
  and Tolman The universe expands from a point
  and eventually contracts back, can repeat forever
  (Contraction now seems unlikely, Hawking Penrose
  and Ellis showed the mathematics would be a train
  wreck string theory revision currently playing
  off Broadway)
• 3. Tired Light hypothesis Photons lose energy
  travelling the long distance, causing the red
  shift (would require several miracles to work out
  just right, that arise naturally in LeMaitres
  theory.)

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Fred Hoyle
Offered the Steady State Theory of the
Universe Worked out large portions of stellar
nucleosynthesis (robbed of Nobel Prize
) Rejected Chemical evolution instead insisting
life on earth came from comets Coined term Big
Bang in effort to ridicule the competiting
theory
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After WWII only 2 contenders remain

• Steady State
• Universe looks the same at all places and times
  forever
• Expansion is driven by creation of new matter,
  approx 1 atom per cubic meter per billion years

• Big Bang
• Universe began with some sudden expansion from
  some small initial state in the distant past
• Expansion might continue, be reversed or slow to
  a stop

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Death of Steady State a Worldview
Steady State Hoyle ( many many others) were
uncomfortable with the idea of a definitive
beginning for the Universe (This is the last
attempt to salvage the static Universe of
Einstein) Steady State predicts that the
Universe should look the same everywhere and all
the time. (It does not, the distant (young)
universe was a very different place, as BB
Cosmology would predict. Discovery of quasars and
radio galaxies only at large distances...) Steady
State theory cannot easily explain why the
Universe creates H, He, and Li in the observed
proportions...
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George Gamow
Student of Friedmann Along with Ralph Alpher
showed that the Big Bang would get the right
proportion of H and He (actually could not
explain how the heavier elements happened, Hoyle
explained this correctly in his nucleosyntheis
work) Work with Alpher in 1948 predicted that if
the Big Bang had occurred, the temperature of the
Universe should be essentially constant in every
direction and about 5 Kelvin
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Right Place - Right Time
Penzias Wilson Building a new radio antenna
for Bell Labs Noise clean pigeon dropping
noise, clean more noise about 3.5 Kelvin too
much Call the boys at Princeton.. Who happen to
be building a radio antenna to search for the
radiation associated with the big bang Boys
we have been scooped.
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End of discussion (for everyone but Hoyle)
Perfect Blackbody to 1 part in 100,000 Error bars
and data points obscured by line thick enough to
be visible
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Big Bang

Incidentally, disturbance from cosmic background
radiation is something we have all experienced.
Tune your television to any channel it doesn't
receive, and about 1 percent of the dancing
static you see is accounted for by this ancient
remnant of the Big Bang. The next time you
complain that there is nothing on, remember that
you can always watch the birth of the universe.
Bill Bryson
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Summary of Evidence for Big Bang

Recession of Galaxies Hubbles Law Cosmic
Microwave Background (CMB) Radiation Relative
abundance of Helium 3, Helium 4, deuterium, and
Lithium 7 (Has proven one of the BBs strongest
pieces of evidence.) Galaxy evolution and
distribution agrees with simulations from hot
dense early state to present era Age of
Universe from Hubble Law and age from CMB agree
approx 13.73 billion years
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Challenges along the way

Globular cluster age Age of collections of
stars was believed to be older than measured
value of age of universe. (Better understanding
of mass loss from stellar wind in late 1990s
removed this embarrassment.) Horizon problem
CMB is too uniform (solved by inflation) Flatness
problem - Unless the universe has a very precise
density it would likely collapse gravitationally
back on itself or quickly expand to the point of
extinction we seem to have avoided both fates.
(solved by inflation) Magnetic monopoles where
are they? Big Bang almost maybe possibly
certainly had to make them(solved by
inflation) Baryon asymmetry - Why does our
universe seem to have only matter and almost no
antimatter? . (?) Dark Matter Not enough
matter in universe (by factor of 5 to 10) to
explain observed gravitational strength and
effects. (??) Dark Energy For the last 7
billion years or so, the expansion of the
universe has been accelerating. (?!_at_ )
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Inflation Universes just cost more than they
used to

Guth Starobinski with modifications by Linde
and others How? Answer(?!!?) -gt Yet many
predictions confirmed by observation The GR is
weird, but not too much unlike an inside out
black hole. Size of space in early universe
expands by a factor of 1026 In something like
0.00000000000000000000000000000000001 s Solves
the problems from previous slides and also
predicts very well the distribution of
galaxies. Very much an open question with
intense debate, but currently the most widely
accepted view, (but perhaps not a majority)
competing views are largely string theoretic in
nature
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Dark Matter

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Dark Matter - Evidence


Zwicky Velocities of galaxies in cluster
implied some hidden miss (1933) Vera Rubin
(1975) Galaxy rotation curve not enough mass to
keep galaxies rotating at observed rates
Gravitational lensing shows separation of
normal matter and dark matter
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Gravitational Lens



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Einsteins Cross
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Bullet Cluster 8 sigma!
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Dark Matter is real! (Probably)
But what is it? How did the Universe make it? And
why so much of it (51 advantage over normal
matter)
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Dark Energy
Type Ia supernova standard candle
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White Dwarf go Boom! 1994D
Type Ia supernova
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What do we find....
Universe is expanding faster now than it once
did. For the apparent density of the universe
from a geometrical standpoint, about 70 of the
energy density is missing... In particular 4 is
normal matter, 22 is dark matter and 74 is
something else...dark energy Hot and cold spots
in CMB radiation
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So what is it? What do we know about it
Homogenous and very sparse, only know to interact
through gravity, corresponding to a density of
10-29 g/cc What ever it is, it must have
negative pressure to give the acceleration Two
explanations in contention Quintessence Cosmologi
cal constant (from the beginning of the show)
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Quintessence
Scalar field which can vary in space and time No
evidence for this yet, but is one of the few
things left that has not been ruled out
(Attempts to modify gravity have been largely
though not completely shot down through recent
observations)
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The cosmological constant
Einsteins biggest blunder to the rescue! But he
had the wrong idea.. It was shown the constant
even finely tuned to lead to an equilibrium was
unstable.. Think of it as the energy required
for space to exist...predicted by most quantum
field theories Slight problem for theory -gt
observed value and predicted value differ By
10120 the worst theoretical prediction in the
history of physics
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Status of your universe now
Our local universe almost certainly began in a
big bang like event, whether it is an absolute
beginning, a part of a larger Universe or a
cyclic one However, very very early Universe is
very much contested -gt many untested ideas as to
how it all got started Future refinements
include first 10-43 s, antimatter, dark matter
and dark energy.
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Timeline until now
Big Bang until t10-43s non-existent theory of
quantum gravity required, four forces of nature
gravity, electro magnetism, weak nuclear, strong
nuclear have same strength and are likely
unified Grand unified era 10-43s to 10-36s
Gravity becomes a separate force, other forces
are unified, only existing particle is the Higgs
boson (as yet undetected, lets go
LHC!) Electroweak - 10-36s to 10-12s universe
cools, strong nuclear force becomes separate
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Timeline until now Part 2
Inflation strikes around 10-36s to 10-32s as
strong nuclear force uncouples from electroweak
some models suggest universe might have even been
empty until inflation releases its energy Quark
era 10-12s to 10-6s forces are all separate and
in their current form , can make quarks but too
hot to make protons neutrons etc Hadron era
10-6s to 1 minute cool enough to make hadrons
protons, neutrons, anti-protons,
anti-neutrons Lepton era -1 to 3 minutes most of
the hadrons and anti-hadrons annihilate each
other leaving leptons behind (electrons
neutrinos)
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Timeline until now Part 3
Nucleosynthesis 3 min to 20 min a 17 minute long
party of nuclear fusion, hydrogen nuclei (i.e.
Protons) fuse to make deuterium and helium and
trace amounts of Lithium nuclei (BB can predict
the ratios very well! Again is hard for any
competing theory to get this right) Photon era 3
min until about 300-400 thousand years photons
scatter frequently off of the matter in the
universe At the end of this era, it has finally
cooled enough that nuclei can hang onto electrons
to some degree and we have neutral hydrogen and
helium.
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Timeline until now Part 4 Skipping ahead
After 150 million years, first structures start
to appear About 500 million years, first
galaxies After about 5 billion years our
galaxy After about 8.5 billion years our solar
system After about 13.7 billion years this
talk....
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The Neighborhood of Planets and space rocks
about 0.01 light year to1 ly
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The Neighborhood of stars out to 12.5 light years
33 stars
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The Neighborhood of stars 250 light years
260,000 stars
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The Neighborhood of stars 5000 ly - 600 million
stars
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The Neighborhood of stars 50,000 light years
200 billion stars
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The Neighborhood of stars, 500,000 ly - 225
billion stars
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The Neighborhood of stars, 5 million ly, 700
billion stars
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The Neighborhood of stars, 100 million ly - 200
trillion stars
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The Neighborhood of stars, 1 billion ly 250,000
trillion stars
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The observable universe of stars, 14 billion ly -
30 billion trillion stars
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The future.... Standard view
In about 3 billion years, the Andromeda galaxy
may collide with us. In about 5 billion years
the sun will die In about 100 billion to 1
trillion years the entire Local Group of galaxies
will coalesce into one large galaxy
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The future....
If the accelerating expansion continues, in 2
trillion years all but the Local supercluster of
galaxies will have disappeared due to red
shifting In 100 trillion years, star formation
will cease In 1 quadrillion years, 1015 years
all planets will have been casts from their
orbits 1020 years, all stellar remnants are
cast from galaxies or fallen into black
holes Proton decay starts at 1032 years, by 1041
years, no protons or neutrons remain
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The future....
Black holes begin decaying, by 10100 years, all
black holes have decayed...leaving electrons,
anti-electrons photons and neutrinos wandering
the enormous universe never seeing each other..
If protons do not decay, postpone this by an
enormous factor... But still is going to
happen
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If it is quintessence in a particular version
however...
The acceleration continues unabated, the fabric
of space is stretched more and more, the
observable universe gets smaller and smaller The
Big Rip - all in the next 50x109 years
Eventually any two chosen points will be
casually separated Galaxies will disappear t
minus 1 billion The Milky Way will come apart
t-minus 60 million years Solar systems become
unbound t-minus 3 months The stars and planets
torn apart t-minus a 30 minutes Atoms destroyed
t-minus a few seconds
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If instead the universe is a false vacuum...

If our universe is in a very long-lived false
vacuum, it is possible that the universe will
tunnel into a lower energy state. If this
happens, all structures will be destroyed
instantaneously, without any forewarning.
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Questions?

If I had only known, I would have been a
locksmith - Albert Einstein