Precision CosmologyThe End Of Cosmology?Horizon ProblemFlatness ProblemInitial Conditions ProblemSolution: InflationInflation 101Quantum Physics on a Cosmic Scale!Is Inflation a Testable Theory?Towards a "Theory of Everything"The Oldest Light In The UniversePhysics of CMB PolarizationSource Terms for PolarizationPolarization PatternsPolarization and InflationShow Me The … Polarization?Angular Scale For PolarizationA Polarized Gold Mine for CosmologyA Polarized Gold Mine for CosmologyA Polarized Gold Mine for CosmologyA Polarized Gold Mine for CosmologyExperimental ChallengesFirst Generation MeasurementsWMAP Full-Sky PolarizationWMAP and Inflation2nd Generation: Add ModulationRotating Quarter-Wave PlateFaraday RotationPhase-Sensitive DetectionPolarimeter On A ChipState Of The Art 2007Towards a B-Mode MachineKilo-Pixel Detector ArraysFuture MissionsExperimental Probe of Inflationary Cosmology (EPIC)Einstein Polarization Interferometer for Cosmology (EPIC)CMB Polarimeter (CPMPol)Plausible AchievabilityPolarization of the Cosmic Microwave Background:Are Those Guys Serious?Al KogutGoddard Space Flight CenterPrecision CosmologyΛCDMLensingGalaxy SurveysCMBStructure formation seeded by adiabatic scale-invariant perturbations6 Parameters get you all this!The End Of Cosmology?Breakfast of TheoristsHorizon ProblemT0= 2.7 K< 10-4ΔTT10,000 Causally disconnected regions: Why is the CMB so uniform?TimeSpaceObserverLast ScatteringBig BangΔt2cΔt1.5ºFlatness ProblemWhy is the universe so flat?Ω = 1 Is Unstable!Now: 0.98 < Ω < 1.02Then: 0.99999999999999999999999999999999999999999999999999999999999 < Ω < 1.00000000000000000000000000000000000000000000000000000000001Primordial Scale-InvariantPower SpectrumCompressionRarefactionCompressionWhat generated primordial density fluctuations?Observed Power SpectrumInitial Conditions ProblemCompressionSolution: InflationInflation BeginsInflation EndsTimeSpaceSmall region in causal contactSame region stretched to macroscopic sizeSolves Flatness ProblemSolves Horizon ProblemStretch e60Stretch e23Stretch e5Scale-Invariant FluctuationsGuth 1981, Linde 1982, Albrecht & Steinhardt 1982Inflation 101T » TcT < TcΦV(Φ)Phase transition at T=Tc drives exponential expansionCase 1: Matter-DominatedCase 2: Vacuum Energy DensityM = Const, d2R< 0dt2dt2M = -V0R3, d2R= RR(t) = R0exp(t)Rd2R GM= -dt2R2Need ~60 e-foldings before inflation endsQuantum Physics on a Cosmic Scale!Quantum Fluctuations …Stretched to Cosmic ScalesIs Inflation a Testable Theory?Prediction Inflation EkpyroticFlat (Ω = 1)Yes YesNo Monopoles Yes YesGaussian Fluations Yes YesScale-Invariant (ns ~ 1) Yes YesSuperhorizon Modes Yes YesGravity Waves Exist Don't ExistSearch for Primordial Gravity Waves via CMB Polarization!Towards a "Theory of Everything"StrongElectro-magneticWeakElectroweakGravityM Theory Quantum TheoryTOETOEM THEORYACCELERATINGUNIVERSEIntersection of Particle Physics and CosmologyThe Oldest Light In The UniverseFossil Relic of Early Universe• GUT Physics at 1016GeV• Inflation/Phase Transitions•Geometry of Space-Time• Contents of Universe• Gravity & Structure FormationPhysics of CMB PolarizationxyzScatteredPhotons• Thomson scattering of anisotropic photon distribution by free electrons• Quadropolar temperature anisotropy produces net linear polarization• Expect few percent linear polarizationIncidentPhotonsWhole New Look at Early UniverseSource Terms for PolarizationGravity WaveTensor SourceGradient (“E mode”) PatternCurl (“B mode”) PatternTemperature QuadrupoleScalar SourceGradient (“E mode”) PatternB-Mode Polarization "Smoking Gun" For Inflation!Polarization PatternsE ModesEven ParityB ModesOdd ParitySuperposition E + BPolarization and InflationInflating Space-Time …Which Sources CMB PolarizationModel-Independent Result:Polarization ~ [ Inflaton Potential ]1/4Creates Gravity-WaveBackground …Show Me The … Polarization?Isotropic CMB-45 dB-60 dB-80 dBTemperature AnisotropyPolarizationE ModesB Modes2.7 K80 μK3 μK3 μK30 nKHierarchy for CMB SignalsB-Mode Detection:• Inflation is real• Determine energy scaleParameterize using Tensor/Scalar ratio rWMAP Prediction: Signal should exist at 30--100 nK!Angular Scale For PolarizationSpaceTimeDecouplingz ~ 1089θ ~ 1ºReionizationz ~ 15θ ~ 30ºIonizedIonizedNeutralBig BangObserverTodayA Polarized Gold Mine for CosmologyA Polarized Gold Mine for CosmologyPhysics at DecouplingA Polarized Gold Mine for CosmologyPhysics at DecouplingReionization& First StarsA Polarized Gold Mine for CosmologyPhysics at DecouplingReionization& First StarsGravity Waves GUT PhysicsExperimental ChallengesFaint Signal• Photon Statistics Limit• Large Arrays of DetectorsAvoid Aliasing Unpolarized Light• Control Stray Light• Modulation/ChoppingPolarized Galactic Foregrounds• Multiple Frequency BandsExEyExEyEyFirst Generation MeasurementsEach detector measures single linear polarizationDifference detectors to get Stokes Q = Ex-EySky rotation maps Q and U22Ex2Ey2Incident LightWMAP, BOOMERanG, QUaD, Planck, …WMAP Full-Sky Polarizationλ = 13 mm050T (μK)7 mm5 mm3 mm9 mmForegrounds brighter than CMBE-mode comparable to B-modePage et al. 2006, ApJ in press, astro-ph/0603450WMAP and InflationHorizonSuper-Horizon ModesTemperature-Polarization Cross-Correlation∂ρ/∂t + ∇•(ρv) = 0Continuity:Observe beating between ρ and vv ≠ 0 on super-horizon scales requires super-horizon potential: Inflation!Peiris et al. 2003, ApJS, 148, 2132nd Generation: Add ModulationTemperature Anisotropy: ΔT/T ~ 10-5Difference 2 beam spots on single detectorExEyMany Approaches In Development!TATBPolarization: ΔP/T < 10-6Difference 2 polarizations on single detectorRotating Quarter-Wave Plateβ2βIncident LightWave PlateRotated LightEBEX schematicRotate polarization on each detector• Macroscopic moving parts• Achromatic plate possible but hard• MAXIPOL, EBEX, SPIDER balloon instrumentsFaraday RotationRotate polarization in magnetic medium•No moving parts• Hand fabrication, high power• BICEP ground-based instrumentBICEP at South Poleβ =e3λ22ε0mec2∫ ne(z) B(z) dzPhase-Sensitive DetectionSwitch Pu= 〈 (Ex+ Ey)2〉Up = Ex2+ Ey2+ 2 ExEySwitch Pd= 〈 (Ex-Ey)2〉Down = Ex2+ Ey2-2 ExEyOutput Pdc= 1/2 〈 Pu+ Pd〉 = Ex2+ Ey2Pac= 1/2 〈 Pu-Pd〉 = 2 ExEyDemodulated Output ~ Linear Polarizationλ/2EyExChopped Phase DelayEx, Ey2ExEy (Stokes U)Ex + Ey(Stokes