L13GUT

Astronomy 350Cosmology: 

Professor Lynn Cominsky Department of Physics and Astronomy Offices: Darwin 329A and NASA EPO (707) 664-2655 Best way to reach me: lynnc@charmian.sonoma.edu Astronomy 350 Cosmology

Group 13: 

Group 13 Philip Domenici Kimberly Doyel Schell Scivally

Extra credit: 

Extra credit You can earn one extra point for each Space Mystery that you try out and evaluate at http://mystery.sonoma.edu Evaluation forms are found at: http://mystery.sonoma.edu/resources/teachers/evaluation.html The mysteries are: Live! From 2-alpha Alien Bandstand Starmarket Evaluation forms must be turned in by 5/27/03 (day of final exam)

Big Bang Timeline: 

Big Bang Timeline We are here Today’s lecture

The Vacuum Era: 

The Vacuum Era Planck era (lecture 11) 10-43 s after the Big Bang Temperature (kT) ~1019 GeV Beginning of time – time and space are no longer separate entities Emergence of spacetime Inflationary era (lecture 11) < 10-10 s, kT ~ 100 GeV Vacuum energy dominates, driving Universe to enormous size Fluctuations may be formed that eventually turn into large scale structure

Radiation Era: 

Radiation Era Creation of Light >10-36 s after Big Bang - kT ~ 100 GeV Vacuum energy turns into light, and equal amounts of matter vs. anti-matter Gravitational attraction begins Background radiation energy originates Dark matter may be formed (lecture 8)

Radiation Era: 

Radiation Era Creation of Baryonic Matter (Baryogenesis) >10-36 s after Big Bang Temperature (kT) ~ 100 GeV A small excess of quarks and electrons is formed (compared to anti-quarks and anti-electrons) Electroweak (Unification) Era 10-10 s after the Big Bang, kT ~ 100 GeV Forces and matter become distinguishable forms of energy with different behavior Masses of particles are defined May include baryogenesis

Radiation Era: 

Radiation Era Strong Era 10-4 s after the Big Bang - kT~ 0.2 Gev Quark soup turns into neutrons and protons Dark matter may be formed Electroweak Decoupling 1 s after the Big Bang - kT ~ 1 MeV Neutrons and protons no longer interchange (leaving 7 p for each n) Cosmic neutrino background is formed Electrons and positrons annihilate, adding energy to the cosmic background radiation, and an excess of electrons

Radiation Era: 

Radiation Era Creation of light element nuclei 100 s after the Big Bang – kT ~ 0.1 MeV Nucleosynthesis begins as neutrons and protons are cool enough to stick together to form Helium, some Deuterium, and a little bit of Lithium Precise elemental abundances are established Radiation Decoupling 1 month after the Big Bang – kT ~ 500 eV Interactions between matter and radiation are fewer and farther between Blackbody background spectrum is determined

Field Theories: 

Field Theories 1865 – James Maxwell unifies electricity and magnetism in the first field theory Fields were proposed to explain how forces are carried between particles Einstein’s theory of General Relativity is another example of a field theory electromagnetic wave

Particles and Fields: 

Particles and Fields Fields carry energy through spacetime Fields are present everywhere, including the vacuum (which is the lowest energy state of all the fields) Fields can act like both waves and particles Wave-like fields are called forces Particle-like fields are called matter or photons Matter interacts with other matter through forces

Quantum Electrodynamics: 

Quantum Electrodynamics Quantum mechanics describes the laws of motion of sub-atomic particles Interactions between sub-atomic particles are described by quantum field theories QED is the quantum field theory which describes electromagnetic interactions at the sub-atomic level Predictions from QED calculations are accurate to one part in a trillion

Quantum Electrodynamics: 

Quantum Electrodynamics The 1965 Nobel prize for QED was awarded to Richard Feynman, Julian Schwinger and Sin-Itiro Tomonaga Feynman diagrams are used to show the relation between particles and force carriers for all four forces

Electro-weak Unification: 

Electro-weak Unification 1979 Nobel Prize awarded to Steven Weinberg, Abdus Salam, and Sheldon Glashow for the development of a unified field theory of electroweak interactions They predicted the W and Z bosons (which were discovered in 1983, Nobel in 1984 to Carlo Rubbia and Simon van der Meer)

Electro-weak Unification: 

Electro-weak Unification Q: If the electromagnetic and weak interactions are really two sides of the same coin, then why are the W and Z particles so massive (80 GeV) while the photon is massless? A: In the early Universe, when the characteristic energy kT > 80 GeV, the electromagnetic and weak forces were united. As the Universe cooled out of the electroweak era, spontaneous symmetry breaking occurred which split out the W and Z

Symmetry Breaking: 

Symmetry Breaking Here is an example: it is unclear which glass goes with which place setting until the first one is chosen

Spontaneous Symmetry Breaking: 

Spontaneous Symmetry Breaking Balance a pencil on its tip – it has an equal chance to fall over in each direction. But when it falls over, it chooses a specific direction, and breaks the initial symmetry Hydrogen and oxygen are symmetric molecules, yet when they combine to make water, the molecule has a characteristic angle of 105 degrees between the Hydrogen atoms.

Symmetries: 

Symmetries Physical laws display mathematical symmetry Rotate a square through space by 90o - it will look exactly the same Rotate a circle by any angle – it will also appear the same Because a circle has more choices of rotation angle, it is said to have a larger symmetry Physical laws can be invariant with respect to changes in location, time or other types of transformations (rotation, velocity, etc.)

Symmetries: 

Symmetries Patterns in the properties of particles can be described by mathematical symmetries which act on internal spaces – properties of the particles themselves, rather than its spacetime environment Protons and neutrons are regarded as two different directions in an abstract internal space – although their charges are different, they have identical strong interactions (“nucleons”) This is another example of a broken symmetry which is thought to be unified at higher energies

Quantum Chromodynamics: 

Quantum Chromodynamics QCD is the quantum field theory which describes the interactions between quarks and gluons It is difficult to use QCD to make predictions because the gluons carry a color charge and interact with each other QCD is a non-linear theory which can only be calculated approximately - 10% accuracy for mass of proton – calculations take months of supercomputer time

Quantum Chromodynamics: 

Quantum Chromodynamics 1969 Nobel to Murray Gell-Mann for quark classification scheme Internal symmetry in the pattern of quarks predicted the W- particle and its mass

Gauge Theories: 

Gauge Theories Gauge theories are quantum field theories that have local symmetries  physical laws remain the same when particle properties are exchanged at different locations in spacetime Local internal symmetries actually require force carrier particles whose interactions create the forces QED is an Abelian gauge theory Electro-weak Unification is a non-Abelian gauge theory (1999 Nobel to t’Hooft and Veltman)

Abelian Transformations: 

Abelian Transformations 2D rotations are the same in either order

Non-Abelian Transformation: 

Non-Abelian Transformation 3D rotations are not the same in either order

Beyond the Standard Model: 

Beyond the Standard Model Standard model describes every particle and interaction that has ever been observed in a laboratory It has 18 arbitrary constants that are put in “by hand” – where do these come from? The masses of the W and Z particles are not easily predictable from the Standard Model The Standard Model also does not predict the pattern of masses and the generational structure – is a new symmetry needed?

18 Free Parameters: 

18 Free Parameters Fundamental electroweak mass scale (1) Strengths of the 3 forces (3) Masses of e-, m and t (3) Masses of u, c and t quarks (3) Masses of d, s and b quarks (3) Strength of flavor changing weak force (3) Magnitude of CP symmetry breaking (1) Higgs boson mass (1)

Grand Unification of Forces: 

Grand Unification of Forces Strengths of three forces depend on the energy at which the observations are made Supersymmetric theories can unify the forces at higher energies than we can observe

Relativistic Heavy Ion Collider: 

Relativistic Heavy Ion Collider Brookhaven National Laboratory Collides gold ions to form quark-gluon plasma to simulate Big Bang conditions QGP has never been made on Earth but should exist inside neutron stars

Relativistic Heavy Ion Collider: 

Relativistic Heavy Ion Collider

RHIC Quark-Gluon Plasma: 

RHIC Quark-Gluon Plasma RHIC collision simulations

RHIC Quark-Gluon Plasma: 

RHIC Quark-Gluon Plasma

Supersymmetry: 

Supersymmetry Supersymmetry is a larger symmetry that treats the 3 forces as broken pieces of a larger whole, and can predict all the properties and interactions of the particles Predicts a combination of coupling constants that agrees with what is measured in the electroweak unification regime Predicts supersymmetric particle partners for each existing particle (the lightest “sparticle” is also known as a WIMP)

Supersymmetry: 

Supersymmetry Sparticles have not yet been seen, but require experiments which can get to energies near 1 TeV GUTs allow the conversion of quarks to leptons through the exchange of a very massive particle Since protons are made of quarks, this interaction would cause protons to decay Non-supersymmetric GUTs predict short lifetimes for protons, and have been ruled out

Proton Decay: 

Proton Decay Supersymmetric predicted proton decay rate is a few per year per 50,000 metric tons (SuperK volume) SuperKamiokande finds a proton lifetime > 1033 years (no events are seen in over three years study of a huge volume of protons) – can eventually reach 1034 years

Proton Decay: 

Proton Decay p  e+ po po  2g, each produces an EM shower e+ also produces an EM shower

Neutrino Oscillations: 

Neutrino Oscillations A pion decays in the upper atmosphere to a muon and a muon neutrino Neutrinos oscillate flavors between muon and tau

Neutrino Oscillations: 

Neutrino Oscillations High energy neutrinos that travel a short distance do not change their flavor Low energy neutrinos that travel a long distance have a 50% chance of changing flavors

Neutrino Oscillations: 

Neutrino Oscillations K2K (KEK to SuperK) is an experiment testing neutrino oscillation results Neutrinos produced at KEK are measured at near detector and then shot 250 km across Japan to SuperK detectors First events reported from run during 1999-2001: 64 expected, 44 detected  oscillations!

Origin of Mass: 

Origin of Mass Electroweak unification predicts the existence of yet another particle, the Higgs boson The Higgs boson is a neutral particle with zero spin which is the force carrier for the Higgs field The Higgs boson breaks the electro-weak symmetry which gives the W and Z much heavier masses than the photon Interactions with the Higgs field are theorized to give mass to all the other particles

Higgs Boson: 

Higgs Boson Supersymmetry predicts the Higgs mass should be less than 150 GeV Present CERN LEP limits are that it must be greater than 90 GeV – hints of finding it at 115 GeV right as LEP was turned off Fermilab limits will be 130 GeV by 2003 CERN’s LHC can reach 150 GeV by 2010 Looking for the Higgs was the goal of the (now-cancelled) Superconducting SuperCollider Higgs boson is aka the “God Particle”

CP Violation: 

CP Violation CP means “charge-parity”, aka time-reversal symmetry – the symmetry that results from interchanging a particle with its anti-particle and sending it through a 3D mirror CP violations were first observed in decays of K-mesons vs. anti-K-mesons – the decays happened at different rates (1980 Nobel, James Cronin and Val Fitch) Studies of flavor changing interactions with K and B mesons should tell us more about CP physics

CP Violation: 

CP Violation Strongest part of the weak force does not change generations Weaker parts of the weak force allow changes in quark generations There are 3 parameters which describe the strength of generation (“flavor”) changing weak force

CP Violation: 

CP Violation Kaons oscillate between two types– short-lived (green) which decay into 2 pions and long-lived (red), which decay into 3 pions Both indirect and direct CP violation have now been observed, The weak force is being held responsible

CP Violation song: 

CP Violation song Written by Logan Whitehurst (formerly of the Jr. Science club, and more recently in the Velvet Teen) for my Cosmology class several years ago Available on mp3.com http://artists.mp3s.com/artists/cds/57/57220.html Sid Sheinberg sings! CP Violation Song

Theory of Everything: 

Theory of Everything Mathematical unification of gravity with the other 3 forces (which are governed by quantum mechanics) Einstein was the first to try (and fail) to develop a ToE – unifying general relativity with quantum mechanics Supersymmetry + quantum gravity and string theory are two attempts to develop a ToE

Anthropic Principle: 

Anthropic Principle Anthropic principle - physical forces and constants are precisely balanced to allow life Is this balance an accident or part of a grand design by a grand designer? If the laws of physics completely explain the creation of the Universe, then what role would there be for a Creator? (Hawking) If there really is a ToE, then the beauty and order of the physical laws indicate that a Creator must have originated the laws (Davies)

Web Resources: 

Web Resources The Particle Adventure http://particleadventure.org/ Georgia State University Hyperphysics http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html National Research Council study of Elementary Particle Physics http://www.nap.edu/readingroom/books/particle/#contents Boston University HEP site http://hep.bu.edu Nobel Prizes http://www.nobel.se Brookhaven National Laboratory (RHIC) http://www.rhic.bnl.gov