Connecting Quarks to the Cosmos

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1 Connecting Quarks to the Cosmos Institute for Nuclear Theory 29 June to 10 July 2009 Inflationary Cosmology II Michael S. Turner Kavli Institute for Cosmological Physics The University of Chicago Michael S Turner

2 Successes of Standard Hot Big Bang Cosmology Big-bang nucleosynthesis Expansion of the Universe CMB Structure formation Tested account from 10-5 sec on Consistent age for the Universe (expansion, stars, radioactive elements)

3 Big Unanswered Questions Just like the questions raised by the SM, not a logical inconsistency but clues about Origin of baryons/large entropy per baryon Dark Matter the grander theory Dark Energy, Cosmic Acceleration, Λ Dynamite behind the big bang Heat of the big bang Isotropy, homogeneity and flatness (not generic initial conditions) Origin of seed inhomogeneity Before the big bang Addressed by Inflation

5 Two Horizon Problems

Two Horizon Problems Said Another Way Said Another Way Horizon at last scattering subtends only 1 degree on the sky; what mechanism causes the temperature to be so uniform on

6 Two Horizon Problems Said Another Way Said Another Way Horizon at last scattering subtends only 1 degree on the sky; what mechanism causes the temperature to be so uniform on scales» 1 degree? Galactic-sized masses entered the horizon about 1 year after the big bang; what causal physics created density perturbations that late in the history of Universe?

7 Cosmic Inflation Addresses isotropy, homogeneity & inhomogeneity, flatness, dynamite, and before the BB Paradigm, not a model Most important idea since big bang Strong evidence supporting inflation (CMB, large-scale structure)

8 Key Elements of Inflation Period of exponential expansion (constant Hubble Constant and horizon size) Tremendous entropy production (called reheating)

9 SOLVING SOLVING

10 Inflation Implemented as Scalar-field Dynamics Theorists: When in doubt, just add a scalar field

11 Homogeneous Scalar-field is Just Like a Fluid -1 Slow roll (flat part of potential): w -1 Rapid oscillation: particle production and conversion of potential energy to particles (heat) aka decay of φ particles

12 Entropy Production/Reheating Adiabatic: Constant Number of Photons per co-moving Volume, i.e., RT = const

13 Solving the Flatness, Horizon Problems

14 Quantum Fluctuations Seed Density Perturbations

15 Given scalar potential V(φ), can compute all observables in terms of V, V and V

16 Q: Where did the almost perfectly smooth quark soup come from? A: Decay of False Vacuum Energy!

17 Q: Where did the small lumps in the quark soup come from? A: Quantum Fluctuations!

19 Important Facts About Inflation 1. Paradigm, no standard model, many viable models (new, chaotic, ) 2. Key predictions Flat Universe: Ω 0 = Almost scale-invariant adiabatic, almost power-law, Gaussian adiabatic fluctuations n-1 ~ 0.1, dn/dlnk ~ 10-3 Almost scale-invariant spectrum of gravitational waves n T ~ 0 to -0.1 (i.e., negative) 3. Consistency relation: T/S = -5n T Unfortunately, T/S not related to n

20 Important Facts About Inflation, cont d 4. Measuring GWs immediately gives scale of inflation! 5. But, no robust prediction for T/S (=r) 6. Inflationary perturbations + Cold Dark Matter + Λ = ΛCDM scenario for structure formation (another test)

21 T/S > if n > 0.9? Hoffman/Turner, PRD 64, (2001)

23 Comments about models 1. Many viable models, non-compelling 2. All based upon a weakly, coupled scalar field with small parameter (e.g., m ~ 10-6 m Pl or λ ~ ) 3. Weakly coupled re-heating is a challenge, perturbations almost Gaussian 4. Very flat potentials 5. No hint about cosmological constant

25 Serious Testing of Inflation Began with WMAP and SDSS

26 CMB anisotropy is a non-trivial map of density inhomogeneity to temperature fluctuations: Mapping depends upon cosmological parameters (good news!) Ω M h 2 Michael S Turner

27 Serious testing of Inflation has begun Key Predictions Flat Universe Almost scale-invariant, Gaussian perturbations: (n-1) ~ 0.1 and dn/dlnk ~ Gravity waves: spectrum, but not amplitude Cold Dark Matter Scenario Key Results Ω 0 = 1.0 ± (n-1) = ± 0.014*; dn/dlnk = ± 0.02; no evidence for nongaussianity r < 0.2 (95% cl)* *Depends significantly upon the priors assumed

28 CDM explains all the structure that exists in the Universe today and all measurements of it only theory that does (circumstantial proof)

32 The Largest Things in the Universe Began from Subatomic Quantum Fluctuations! WOW!

33 Quantum World Projected Across the Sky by the Expansion of the Universe < one billionth the size of a proton

34 GWs: : The Smokin Gun Test of Inflation Directly reveals epoch of inflation Spectrum provides consistency check: T/S=-5n T Reconstruction of scalar potential NB: n T = -(T/S)/5 Direct detection: LIGO & LISA unlikely Big Bang Observer (NASA Beyond Einstein concept) B mode of CMB polarization

35 Reconstruction small T/S large T/S small n-1 large n-1

36 CMB Anisotropy from Gravity Waves ΘΘ = GW temp EE = E mode (scalar) g lensing: grav lensing of EE BB/g waves = GW B-mode

38 Inflation: The Challenges Precision testing: measure and Ω 0 & n-1 (to ±0.001), dn/dlnk (±0.001), search for nongaussianity Detection of GW: T/S (B modes or directly) Measure n T (need direct direction) Fundamental theory of inflation: Who is φ? Successor to inflation ( it seems like duct tape) Laboratory test of inflation (e.g., produce a φ)

39 Summary Inflation is a central part of the consensus cosmology ( most important idea since the big bang itself ) Strong, but not compelling evidence for inflation Important tests and challenges remain

40 Inflation might be the dynamite of the Big Bang, But what happened before the Big Bang?

41 neat & tidy! but Einstein s theory does not incorporate quantum mechanics. and the conditions at the beginning are precisely where quantum effects should be critical!

42 Einstein got the right answer for the wrong reason! = Emergence of space and time

44 THE MULTIVERSE

45 IS IT SCIENCE IF IT IS NOT TESTABLE?

46 We Can Test Whether or Not Our Piece of the Multiverse Originated From Inflation well on our way to doing so

Structures in the early Universe. Particle Astrophysics chapter 8 Lecture 4

Structures in the early Universe Particle Astrophysics chapter 8 Lecture 4 overview Part 1: problems in Standard Model of Cosmology: horizon and flatness problems presence of structures Part : Need for