The Universe Characteristics –Expanding (Hubble’s Law) –Finite age –Cool now, hotter long ago –Composition 70% H, 28% He, 2% the rest – Why? –Most matter is dark (unseen) –Most content is dark energy > gravity Accelerates the Universe’s expansion

Universe Content Matter –Composed of elementary particles –QED – quantum electrodynamic theory –Quarks, leptons, lions, tigers, and bears, oh my! –These particles interact via force carriers 3 out of 4 forces covered – gravity not How did this stuff form? How does it behave under extreme conditions?

Quarks u – up +2/3 c – charm Mass > s t – top Heaviest  – photon E-M d – down -1/3 s – strange Mass > d,u b – bottom Mass>c g – gluonStrong Nuclear Lepton s e – electron neutrino  – mu neutrino  – tau neutrino Z – z bosonWeak Nuclear e – electron  – muon Mass>e  – tau Mass>  W – w boson Proton = uud Neutron = udd

Universe’s Energy Total Energy = Energy of motion + Energy of gravity Combined with other laws to get the Friedmann Equation - H = Hubble’s “constant”H, , R are  = density of the Universe time dependent k = curvature measure R = scale of the Universe

k > 0 Positive curvature, hyperbolic shape Kinetic Energy rules Open Universe Eventually…. –10 12 – years - Star formation ends –10 20 years – Galaxy mergers end –10 30 years – Galaxy death (massive black hole) – years – proton decay years – black hole evaporation –Eventually “heat death”

k < 0 Negative curvature, spherical shape Gravity rules Closed Universe Eventually… –Galaxy redshifts become blueshifts –Universe’s temperature increases –Cluster collisions –Black hole growth, matter evaporation –Total collapse

k = 0 No curvature, Flat Perfect balance between gravity, energy Marginally Open Eventually –Like the k>0 case, but slower Which is it? Define critical density

Other options? Einstein’s Idea –Static Universe –No motion requires anti- gravity effect –Change the formulae The Field Equations  = Cosmological Constant An “anti-gravity” term That can’t really exist, can it?

1997 West Coast – Supernova Cosmology Project East Coast – High-z Supernova Team Type I SN – best for great distances –Testing expansion rate of the Universe –How much is gravity slowing the expansion? –How fast was the expansion in the past? –Current expansion rate? (Hubble constant)

Low redshifts

Where is the SN?

Higher redshifts Best result is case Where  0! Also find k=0

 > 0 Universe  > 0 Accelerating Universe k =0 implies a Flat Universe Density of the Universe = Critical Density? What is the “density” –Matter Dark and regular –Energy (remember E=mc 2 ) Energy of light, radiation Energy of motion - gravity Energy of motion – anti-gravity!

Continual acceleration? –No, varies with z (distance) –Initial deceleration for z>1 –Acceleration took over later, z<1

Confusing terms k=curvature (0 = Flat, 0 Open) Define  Flat, 1 Closed)  =cosmological constant –Also written as   M = matter density (regular and dark) –Also written as  M General rule -  =   +  M

Universal Light - CMBR Cosmic Microwave Background Radiation –Everywhere –Black body temperature = K –First detected in 1963 by Penzias, Wilson

WMAP Results Launched 2001 First results – 2003 –Flat (k=0,  =1) –Age = 13.7 billion years –Hubble Constant = 72 km/s/Mpc –Most of the Universe = Dark Energy –  M =.27 –   =.73

Same results - Supernova projects CMBR projects Galaxy Cluster projects

Options for the Universe?

Big Rip   should increase with expansion Lead to a tearing apart of all matter? When? ~22 Billion years from now Galaxy cluster dissolve (1 Gyr before end) Galaxies dissolve (60 Myr before end) Solar systems dissolve (3 months before end) Planets dissolve (1/2 hour before end) Atoms dissolve ( seconds before end)