Download CosmoSummary - Boston University Physics

…a review of WR150 Cosmology
from the Big Bang
...to the demise of the Universe
…exploring our micro and macro world
Larry Sulak
Boston University
…2 theories: crowning achievement of a century of detailed research
by physicists, with the best of microscopes,
the Standard Theory of Particle Physics
by astronomers, with the best of telescopes,
a Standard Theory of Cosmology
Let’s look at what we know of each,
and how we’ve discovered what we know
…a couple of slides for an overview of each of the 2 theories…
the Standard Theory of the quantum world
Fermions (3×4 on the left)
• Quarks and leptons…
the most fundamental of particles
• “Ordinary” matter =
up “u” & down “d” quarks and
the electron “e-”
• heavier quarks and leptons in
cosmic rays & particle accelerators
(also, each particle has a corresponding
antiparticle with all charges opposite,
e.g., e+ for the + electron, the positron )
FERMILAB
…the baby (building) blocks of the universe
The Periodic Chart of Particles (cont’d)
Bosons, carriers of force (right column)
• Photons (γ) mediate
electromagnetism,
holding the - electrons to + nucleus
• Gluons (g) carry strong force –
holding quarks together,
e.g. against proton-proton charge repulsion,
giving us all the different elements
• Z and W weak bosons
induce weak (radioactive) interactions
allowing the sun to burn slowly
FERMILAB
speculation: in the earliest epoch, the Grand Unified Theory (GUT) era,
one primordial particle, one primitive force
…6 kinds of quarks? 6 types of leptons?
Why “ordinarily” only see
electrons?
floating around atomic nuclei
up and down quarks?
(the constituents of the proton and neutron in the nucleus)
Weak interactions, the W and Z,
cause massive quarks and leptons to decay
into the lightest quarks and leptons
of our cold world
PDG LBL
they were all there in the heat of the Big Bang!
she loves me not…she loves me, at the quantum scale
Fermions...The Matter Particles
electrons, nucleons...leptons and quarks
subject to Pauli exclusion...only 1 in each state
Pauli Exclusion Principle for fermions:
no two identical fermions in the same state
in the same place at the same time
must have different spin, color charge, angular momentum
vs.
Bosons...The Force Particles…want to stick together
photons, gluons, W & Z particles
integer intrinsic spin = 0, 1, 2…spinning little quantum tops
want to be as close together as possible
…as the photons of light from my laser pointer
PDG LBL
A picture gallery of the quantum world:
people’s pictures…unimaginably insufficient
the atom, its nucleus, a proton inside it,
and the quarks + gluons inside the proton
SCIENTIFIC
AMERICAN
the proton, on average = ~ 3 point-like quarks with “strong color” charge
held together by “colored” gluons of the strong force
color = the generalized charge exchanged by gluons, math same as color
proton
neutron
THOMSON – BROOKS/COLE
…but, under the best of microscopes, i.e. the highest energy accelerators
the up and down quarks are pointlike
…anatomy of a proton graphically, again with flaws…
SCIENTIFIC AMERICAN
…artist’s error: colored quarks and bi-colored gluons are point-like
inhabiting a "bag" 10-13 cm across, 1/100,000 as big as the atom
Wave/Particle Duality of Quanta
…electrons, photons, every fundamental particle
“Wave packets” = localized quantum waves
whose amplitudes decrease from the central location
where there is a high probability of finding a particle
blow up a helium atom
proton to the size of
your fist,
electron and quarks the
size of a hair
electron of atom
half way to the airport
…the atom
is utterly empty
PDG LBL
…3 of the 4 fundamental interactions,
as Feynman taught us to calculate
with his graphs representing mathematical integrals…
Electromagnetic
2 Weak Interaction Diagrams
Strong Interaction
…very similar to antenna theory…upper left = WBUR
SCIENTIFIC AMERICAN
…successes of the Standard Theory of Particles
• predicts all known particles and three of the four forces
• all predicted particles found experimentally
(except Higgs…2010 Geneva?)
• simple, only 6 quarks, 6 leptons
4 force-carrying particles
• explains hundreds of particles
and all their complex interactions
…an example? an experiment I had the pleasure of helping initiate
measuring the magnetic “spin” of the muon
(the obese brother of the electron)
after years of supercomputer time,
Standard Theory = 11 659 180 (±5.6) x 10-10
20 year Experiment = 11 659 208 (±6) x 10-10
…theory predictive to 7 digits of accuracy!!!
largest, most uniform superconducting magnet,
a bottle for muons to spin around it
…the failures of the Standard Model?
No explanation for
• The structure of this "periodic chart"
• Origin of masses of particles (next)
• Gravity isn’t there
• (No Dark matter or dark energy)
…enter Grand Unification (and string theory, etc.)
The Problem of Mass?
look at the masses of elementary particles graphically...
Why is the top quark 200 times heavier than the proton?
or 1013 more than the neutrino scale???
a Nobel prize awaits your generation
What is the origin of mass?
Higgs particle, supersymmetry, new force...
…the vision of phase transitions for Grand Unified Theories:
(by analogy for H2O, from ice, to water, to vapor, to plasma)
ADDISON WESLEY
…now that we’ve reviewed a bit about
the Standard Theory of Elementary Particles…
let’s look at
the Standard Theory of Cosmology
theory of cosmology on a poster
…the phase transitions of the universe…as seen by a cosmologist…
…same scenario, just the opposite direction
THOMSON – BROOKS/COLE
Cosmological
Redshift
GUT Era
Lasts from
Planck time
(~10-43 sec) to
end of GUT
force (~10-38
sec)
Inflation of
universe flattens
overall
geometry like
the inflation of a
balloon, causing
overall density
of matter plus
energy to be
very close to
critical density
Inflation
Electroweak
Era
Lasts from end
of GUT force
(~10-38 sec) to
end of
electroweak
force (~10-10
sec)
Particle Era
Amounts of
matter and
antimatter
nearly equal
(Roughly 1
extra proton
for every 109
protonantiproton
pairs!)
Photons converted into
particle-antiparticle pairs
and vice-versa
E = mc2
Early universe was full of
particles and radiation
because of its high
temperature
Era of Nucleosynthesis
Begins when
matter
annihilates
remaining
antimatter at
~ 0.001 sec
Nuclei begin to
fuse
Era of Nuclei
Helium nuclei
form at age
~ 3 minutes
Universe has
become too
cool to blast
helium apart
From the era of
nuclei
to the era of
atoms:
Liberation of the
last light of
the Big Bang
Era of Atoms
Atoms form
after
~400,000years
Big bang light
liberated
…free flowing
til our epoch
Era of
Galaxies
Galaxies form
after ~ 1
billion years
A Short History of the Universe - I
time = 0 Big Bang:
gravity unified with other forces?
10-43 to 10-32 sec old
Age of quarks and gluons
dense plasma of matter, antimatter
gravity becomes a separate force
gradually more quarks than antiquarks
(10-35 sec)
Inflation period of rapid expansion
strong force separates from electroweak
10-32 to 10-6 sec old
Age of Leptons:
leptons become distinct from quarks
>10-12 sec, W and Z bosons mediate weak force
A Short History of the Universe - II
10-6 sec to 3 min
Age of Nucleons and Antinucleons:
3 quarks bind together to form p and n
(“color” is flavor, up=red, down=blue)
energy (temperature) < 2 GeV,
cannot make nucleon-antinucleon pairs
3 min to 107 sec:
Age of Nuclei (nucleosynthesis)
temp < 1.3 MeV, deuteron binding energy
eventual mass ratio 74% H,
25% He,
1% light nuclei
A Short History of the Universe – III
15 min (103 sec) to 1013 sec
Age of Ions:
expanding, cooling plasma of ions
1H+ (proton), 4He++ , e+, etemp > me = 0.5 MeV,
e+ e- ↔ γγ equilibrium
1013 sec = 1/3 Myear
Age of Atoms: temp < 13.6 eV,
H atom binding energy
neutral H, then He, atoms form
universe becomes transparent
CMB photons decoupled from e+ ecooling to 3° radiation filling universe today
A Short History of the Universe - IV
today in big stars
Age of Stars and Galaxies:
thermonuclear fusion in stars
makes
p + (p) → p + (n e+ e) weak int.
d + p → 3He
→
3He + n → 4He an alpha
particle
triple alpha resonance (3Be*)
makes carbon
then oxygen, if star big enough
…iron, if star even bigger
Age of Supernova:
big star collapse if > 3msun
shockwave forms nuclei > iron
How do we know these facts about our universe?
look back to earliest times…seeing light left over from the big bang explosion?
Penzias & Wilson with Bell Labs horn antenna
see “ television snow” in all directions
…scrubbing does not eliminate “noise”
AMERICAN INSTITUTE OF PHYSICS
AMERICAN INSTITUTE OF PHYSICS
looking all directions, with today’s best satellite, see baby picture of our universe…
3º Kelvin light, everywhere we look,
with wimpering fluctuations of only 1/100,000 of a degree
red hot spots show fluctuations that later “seeded” galaxies
cool blue spots became the voids between clusters of galaxies today
looking out, in the dark voids, the “last light” of the big bang
If universe were
1) infinite
2) unchanging
3) everywhere
the same
then, stars would
cover the night sky
Olbers’ Paradox
…and the macro universe is utterly empty too
Night sky is
dark because
the universe
changes with
time
As we look out
in space, we
look back to a
time when
there were no
stars
Maps of galaxy positions reveal extremely large
structures: superclusters and voids
A Supercomputer
Model:
Evolution of Largescale structure of
the universe
from uniform fuzz
to clumps and voids
of today
Time in billions of years
0.5
2.2
5.9
8.6
13.7
13
35
70
93
140
Size of expanding box in millions of lt-yrs
Models show that gravity of dark matter pulls mass into
denser regions – universe grows lumpier with time
using oldest light in the sky, extrapolate from infant universe to today
NASA - WILKENSON MICROWAVE ANISOTROPY PROBE
…extrapolating into the future…
depends upon the total mass in the universe and any new force
accelerating universe: best fit to supernova data
…with all scenarios, what is our ultimate fate, the evolution of matter?
unification of all forces and all particles:
quarks and leptons must ultimately be one in the same,
at the highest energies, earliest times in the universe
the most likely demise of the proton in GUT theories is
p → e+ γ γ ,
but in our world, for every proton, there is an electron
cf. the hydrogen atom inside H20
the positron (positive electron, antiparticle of the electron)
annihilates the electron
e- + p → e- + ( e+ γ γ ) → γ γ γ γ
...ashes to ashes, dust to light
…but at what rate, this proton decay? what lifetime?
Extrapolate to high energy,
All three forces unite at
unique energy
unique force…
Giving a lifetime of 10292 years
universe is 13.7 ×1010 years
…alternative model (supersymmetry)
~ perfect unification of forces
For higher energies,
a truly Grand Unified Theory
of the four forces?
SCIENTIFIC AMERICAN
One Nobel physicist Shelly Glashow:
“Supersymmetry...has generated so many thousands of papers it must be correct”
…if a proton were to decay, say in water, what would it look like?
IMB Proton Decay Detector (1983)
2000 photomultipliers and light collectors
world’s purist water
½ mile under Lake Erie
dry suit diver/physicist
Supernova…all elements beyond iron borne in shockwave...
iodine, silver, gold, uranium
...and fusion energy codes verified
the night before 23 Feb 87
4 hours after neutrino burst
then bam…“vertex-eye” view of one of the neutrinos from supernova
SuperNova!
Cover Story
death throes of a heavy star: as bright as an entire galaxy (1011 stars)…
but supernova brillance
in neutrinos
1000 times more
than in light
point back to find the origin of the low energy neutrinos...
SVOBODA
Super-K “sees” a neutrino heliograph, as the sun was a few minutes ago
…not as our eyes see, photons from a million years
neutrinos from the atmosphere, the sun, a supernova…
what about the center of our galaxy?
…does the Milky Way, and every other galaxy,
have a Black Hole of a million sun’s mass holding it together?
best we can do:
Orbits of
Infrared stars
around
Black Hole (?)
at the Center
of Milky Way
…from the big bang…to the end of the universe
Glashow’s snake eating its tail…
the world’s very largest and the very smallest are intimately linked
above all, science is experimental…surprises are highly likely
Image credits:
D. Perkins, High Energy Physics, 1987
C. D. Coughlan and J. E. Dodd, Ideas of Particle Physics, 1991
The Cosmic Perspective, Pearson - Addison Wesley, 2004
The Particle Adventure, Lawrence Berkeley Laboratory
Scientific American, G. Kane, Jan 2005; Kajita et al, 2003
http://bu.physics.edu/~sulak
stay tuned…
and bon voyage