Basic observed parameters Age: 13.7 By measured by the spacecraft WMAP Data from the cosmic...
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Transcript of Basic observed parameters Age: 13.7 By measured by the spacecraft WMAP Data from the cosmic...
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 Ω = 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)
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
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
Quarks
Make up the particle family known as hadrons which include two families
Baryons – composed of three quarksProtons and neutronsStable
Mesons – composed of two quarksShort lived
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
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
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
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
Particle and force details, including spin (upper right) and rest mass energy (bottom)
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
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
T + 10-20 sec - Baryonic particles form
p+, e-, no, ν (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)
T + 1 sec - Nucleus formation begins
Temperatures sufficiently low to begin forming proton-neutron pairs and triplets
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
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
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)
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
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)
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
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
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
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
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
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)
Comparison maps of the older COBE data and the newer WMAP data
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
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
CMBR Spectral Fit
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
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
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
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
<1 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
Evolution of the universe
Standard Model baryonic content stable since protons have >1033 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
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
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 Λ, 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
Standard Model of particles and forces
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)?
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
3. What is dark energy and what are its physical laws?
All that is known is that dark energy:
Dominates the universe’s total mass and energy
Is measurable over the largest scales
Appeared approximately 5 By after the Big Bang
4. What is the nature of the inflationary event that expanded the initial universe and that continues today?