The Universe: Part 2

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The Universe Part 2
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Universe

• Basic observed parameters
• Age 13.7 By measured by the spacecraft WMAP
• Data from the cosmic microwave background
  radiation (CMBR)
• Diameter Best model is 45 Bly
• Composition
• 73 dark energy
• 23 dark matter
• 4 atomic (baryonic) material
• 75 H, 25 He (originally)
• Critical density O 1.0 measured by WMAP data
• Measured density of universe to the value at
  infinite expansion
• This means the universe is inflationary
  (expansion was faster than known physical laws
  allow)

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Early Universe

• Early chronology of the universe
• The first instant of the Big Bang model of the
  universe is not observable since our
  understanding physics allows only the baryonic
  (atomic) certainty to begin at the Planck time
  10-43 sec
• From this early start, the universe entered an
  inflationary expansion of 50 orders of magnitude
  in 10-32 sec
• Called the inflation period
• First to appear were the forces, but combined
  into a single force
• The first to separate was the weakest - gravity

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Early Universe

• Energy and matter condensed as the universe
  cooled
• First stuff to form were the constituents of
  atomic particles
• Quarks and leptons
• Quarks
• Heavy particles are ruled by the strong nuclear
  force
• Leptons
• Light particles are ruled by the weak force

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Early Universe

• Quarks
• Make up the particle family known as hadrons
  which include two families
• Baryons composed of three quarks
• Protons and neutrons
• Stable
• Mesons composed of two quarks
• Short lived

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Early Universe

• Quarks
• Quarks come in 6 varieties (flavors), each with
  an anti-particle
• Up 1st generation - lightest
• Down - 1st generation
• Charm 2nd generation - heavier
• Strange 2nd generation
• Top 3rd generation - heaviest
• Bottom 3rd generation

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Early Universe

• Quarks
• 2nd and 3rd generation quarks are short lived and
  decay into the 1st generation particles through
  the weak interaction
• Quarks bound by the strong force (gluon)
• Strong force is unusual in that it becomes
  stronger with increasing distance
• No single quarks exist unless at extremely high
  energies
• Atomic/baryonic nuclei are all up/down quarks

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Early Universe

• Leptons lighter particle family that includes
• 1. Electrons (1 type of electron, plus
  antielectron)
• 2. Muons (2 types of muon that include tau and
  mu, and their antiparticles)
• 3. Neutrinos (3 types of neutrinos that include
  the electron, mu and tau species, and their
  antineutrinos)
• Participate in weak force but not in strong force
• Created or absorbed in quark transformations

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Particle Universe

• Quarks and leptons are shown in the diagram as
  1st, 2nd, or 3rd generation particles, along with
  the forces portrayed on the right as force
  carriers

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Particle Universe

• Particle and force details, including spin (upper
  right) and rest mass energy (bottom)

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Universe Chronology
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Universe - Chronology

• T 10-40 sec  -  First stuff forms
• Building blocks for "elementary" particles -
  quarks, gluons, etc.
• Basic four physical forces established and act as
  a unified field
• Gravity separates from the rest of the forces

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Universe - Chronology

• T 10-35 sec  - Inflationary phase of expansion
• A phase transition in the energy/material expands
  the universe by a factor of 1050 in 10-32 sec
• Strong force separates from the remaining
  electro-weak force

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Universe - Chronology

• T 10-20 sec  -  Baryonic particles form
• p,  e-, no, ? (protons, electrons, neutrons,
  neutrinos)
• Universe is composed of a mixture of
  electromagnetic (EM) radiation (photons) and
  charged particles (p, e-)
• Brief condition that allows fusion of particles
  produces proton-to-neutron ratio that results in
  a 75 H and 25 He mix (plus a very little
  deuterium (2H), 3He, and lithium)

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Universe - Chronology

• T   1 sec  -  Nucleus formation begins
• Temperatures sufficiently low to begin forming
  proton-neutron pairs and triplets

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Universe - Chronology

• T 385,000 yr  -  Particle and EM radiation mix
  expands and cools to form first neutral atoms
• p and e- cool sufficiently to form hydrogen
  which dominated the early baryonic (atomic)
  universe
• The universe quickly becomes transparent
  (uncoupling of mass and energy)
• Cosmic background radiation (CBR) created at this
  time and at a temperature of about 3,000 K
• Ionization temperature of hydrogen

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Universe - Chronology

• T 400 Myr -  First stars form
• Hydrogen and helium gas in dense pockets cool
  enough to form the first stars that are
• Massive since there is no efficient method of
  cooling
• Massive since there is a large critical density
  to overcome the high thermal pressure
• Recent star formation is much easier and faster
  since metals (anything heavier than helium) helps
  cool the molecular gas clouds for collapse into
  stars
• The lights in the universe turn on for the first
  time since they dimmed at T 500,000 years

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Universe - Chronology

• T 109 yr  -  First small galaxies form
• Formation site of these dwarf galaxies takes
  place in the higher density regions implied by
  the CMBR maps showing elevated density
• Dwarf galaxies become the building blocks of
  larger galaxies similar to planetesimals
  accreting to form planets and moons
• Hubble deep-field images show ragged, blue dwarf
  galaxies at the largest distance (earliest age)

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Hubble ultra deep field image of distant galaxies
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Universe - Chronology

• Large structures
• The first stars and galaxies to form were in
  enhanced density regions that later became the
  dominant clusters and superclusters of galaxies
• Mass dominated by dark matter

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Simulated galaxy supercluster structure
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Universe - Chronology

• T 10x109 yr (10 By)        Solar system forms
• Molecular gas cloud dominated by hydrogen
  fragments and collapses into a star and planetary
  disk
• Enrichment of 5 dust and metals from dying stars
  including supernova (large stars) and planetary
  nebulae (medium or small stars)

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Universe - Chronology

• T 13.7x109 yr (13.7 By)    Today
• Cosmic background radiation now 2.73 K
• Expansion of universe measurable on scale of
  millions of light years but not on smaller scales
  because of the gravitational grip on close and/or
  clustered galaxies
• Universe expansion is accelerating, caused
  possibly by dark energy

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Cosmic Background Radiation
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Universe

• Cosmic background radiation
• The beginning of the universe was a violent
  expansion with a near-infinite density and
  temperature that rapidly expanded and cooled
• Pure energy contained in the hot matter soon
  formed the first particles and forces
• The production of particles included the baryons
  made of quarks, and leptons that include
  electrons and light, short-lived particles
• These makes up the atomic world we are familiar
  with, but has a variety of other particles

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Universe - Cosmic Background Radiation

• Formation of baryons (primarily protons and
  neutrons) occurred after the quarks cooled
  sufficiently approximately 10-20 sec after the
  Big Bang
• Hydrogen was fused into helium in the first few
  seconds
• Further expansion and cooling of the universe
  reached the 3,000 K ionization temperature of
  hydrogen after approximately 380,000 years
• Because the particle universe was dominated by
  hydrogen, the neutral hydrogen atoms released the
  electromagnetic energy (light) strongly held by
  the previously charged particles

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Universe - Cosmic Background Radiation

• The uncoupled light still contained the signature
  of the hydrogen, helium, as well as the remaining
  electrons, the dark matter and dark energy, the
  acoustic waves, and much more
• As the light and mass continued to expand, the
  light was reduced in temperature, going from
  3,000 K to roughly 3 K in 13.7 By
• This is the 3 K cosmic microwave background
  radiation that still contains the secrets of the
  formation of the early universe

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Universe - Cosmic Background Radiation

• The 2.73 K cosmic background radiation has a peak
  emission in the microwave band near 90 GHz
• The radiation has become known as the cosmic
  microwave background radiation (CMBR) because of
  its frequency range
• Sensitive receiver in orbiting spacecraft are
  needed to measure the CMBR with enough
  sensitivity to determine the small variations
  imprinted by the early universe

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Universe - Cosmic Background Radiation

• The first maps made of the CMBR were done in
  patches using balloon-borne instruments
• The first dedicated satellite used to map the
  CMBR was the Cosmic Background Explorer (COBE)
  launched in November 1989
• A more accurate and sensitive spacecraft named
  the Wilkinson Microwave Anisotropy Probe (WMAP)
  was launched in 2001 and placed in the Sun-Earth
  L2 Lagrange point (WMAP shown on the right)

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Universe - Cosmic Background Radiation

• Comparison maps of the older COBE data and the
  newer WMAP data

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Universe - Cosmic Background Radiation

• While the data presented in the full-sky map of
  the WMAP output appears chaotic, plotting a power
  spectrum of the positions, angle of separation,
  and number of data peaks produces a curve
  representing the influences of various states of
  mass and energy, as well as time
• The power spectrum shown on the right includes
  the compiled data from WMAP (blue continuous
  line) in addition to data from earlier spacecraft
  and balloon-borne missions

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Universe - Cosmic Background Radiation

• By fitting the influence of various parameters to
  the actual day, specific values for the age of
  the universe, the density of the universe, the
  composition of the universe, and a host of other
  physical characteristics can be determined
• The plot shown on the right for example shows an
  obviously poor fit of an open universe in which
  the universe continues to expand forever to the
  actual CMBR data

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Universe - Cosmic Background Radiation

• CMBR Spectral Fit

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Universe Fitting the Big Bang Theory to the Data
Interpretation Observations
Earliest dataUniverse is limited in age Night sky is dark (Obler's paradox)

Early quantitative results
Edwin HubbleUniverse is expanding Galaxy expansion increases with distance
Penzias WilsonCosmic fireball exists Heat left behind by the Big Band is now the cosmic microwave background radiation (CMBR) at 2.73 K

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Universe Fitting the Big Bang Theory to the Data
Interpretation Observations
Recent results
Universe expansion is inflationary CMBR pattern, accurate supernova measurements in distant galaxies
Dark energy dominates universe (73 of mass/energy) CMBR pattern, accurate supernova measurements in distant galaxies
Age of universe is 13.7 0.1 By CMBR pattern, universe expansion rate, oldest stars
Small percentage of atomic (visible) material makes up the universe CMBR pattern, galaxy dynamics, galaxy clusters, H/He ratio, inflationary expansion
Dark matter dominates galaxies and clusters CMBR pattern, galaxy dynamics, galaxy cluster dynamics, galaxy evolution
The first stars formed after approximately 400 million years CMBR pattern
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Universe - Other Components
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Universe Other Components

• Dark energy
• Details unknown, but is contained in empty
  space
• Accelerates expanding universe after first 5 By
  that was first slowing down from self-gravity
• Dark matter
• Details of material unknown
• Contained in large galaxies and clusters of
  galaxies
• Makes up roughly 90 of all large galaxies mass
• Both dark energy and dark matter are observed by
  their gravitational effects on both light (EM
  radiation) and on baryonic (atomic) material

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Universe Other Components

• First stars
• Universe expanded and cooled sufficiently to
  allow gas concentrations to form massive stars
• Approximately 400,000 My after Big Bang
• First stars were 100 Mo to 500 Mo (solar masses)
• Pure hydrogen and helium (75/25)
• Short lifetimes
• lt1 My
• Created first atoms heavier than He
• Can be observed indirectly by their bright UV
  light ionizing the surrounding gas
• May be observed in the James Webb Next Generation
  Telescope that replaces the Hubble space Telescope

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Simulated galaxy supercluster structure
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Universe Other Components

• Evolution of the universe
• Standard Model baryonic content stable since
  protons have gt1033 yr
• This means that there is a lifetime of the
  universe with three possibilities for its end
• 1  Open universeDensity is less than that
  required to recollapse the universe after its
  explosive beginning and continues to expand
  without limit - not supported by the WMAP data
• 2  Closed universeDensity of the universe is
  greater than critical density and will recollapse
  to produce one or possibly many cycles - not
  supported by the WMAP data
• 3  Inflationary (flat) universeThe universe is
  exactly balanced in potential and kinetic energy
  and continues expanding, but only until it
  reaches an infinite radius at infinite time -
  supported by the WMAP data

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Universe Other Components

• Standard Model
• The Standard Model of particles and forces does
  have limitations
• The simplicity of the model cannot account for
  quantum gravity, one of the most difficult
  problems confronting physicists today
• The Standard Model provides no insight into the
  matter-antimatter asymmetry of the universe (all
  particles, few or no antiparticle mass remains)
• Extensions of the Standard Model have been more
  successful at reaching a successful theory of all
  particles and forces

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Universe Other Components

• Standard Model
• Even with the more comprehensive treatment of
  gravity and mass, and with other important
  details from super symmetry, string and
  superstring theory, and inflation theory, have
  not yet answered the question of dark energy and
  dark matter, nor of quantum-scale gravity
• What first surfaced as Albert Einstein's
  controversial cosmological constant ?, the dark
  (vacuum) energy that permeates empty space has a
  profound implication for the model of mass,
  energy and forces
• Understanding dark energy and dark matter may
  lead to the successful theory of "everything a
  complete set of consistent equations of
  particles, forces, and energies

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Universe Other Components

• Standard Model of particles and forces

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Universe Unanswered Questions
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Universe Unanswered Questions

• 1. What is gravity?  
• How does it relate to the other forces?
• What determines gravitational mass?
• How does gravity relate to dark energy?
• How does gravity relate to dark mass?
• How is gravity defined in collapsed matter (black
  holes)?

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Universe Unanswered Questions

• 2. What is dark matter and what are its physical
  laws?
• To date, what is known is that it
• Can be measured by its gravitational affect  on
  galaxies
• Collects in galaxies, galaxy groups, and galaxy
  clusters
• Is not observed in small galaxies or on a scale
  smaller than a galaxy
• Has a "cold" character since it would quickly
  dissipate if it were warm/hot

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Universe Unanswered Questions

• 3. What is dark energy and what are its physical
  laws?
• All that is known is that dark energy
• Dominates the universes total mass and energy
• Is measurable over the largest scales
• Appeared approximately 5 By after the Big Bang

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Universe Unanswered Questions

• 4. What is the nature of the inflationary event
  that expanded the initial universe and that
  continues today?

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And More Questions!