W. Kinney - Scale-Invariant Perturbations: is Inflation the only Way?
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The SEENET-MTP Workshop BW2011 Particle Physics from TeV to Plank Scale 28 August – 1 September 2011, Donji Milanovac, Serbia
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W. Kinney - Scale-Invariant Perturbations: is Inflation the only Way?
- 1. Inflation … Or What? Will Kinney SeenetMTP Workshop Balkan Summer Institute, Donji Milanovac 31 August 2011
- 2. CMB: Basic Properties Adiabatic density perturbations Superhorizon correlations Gaussian statistics Near scaleinvariance over a factor of 1000 in wavelength Q: What does this really tell us?
- 3. Generation of Perturbations Horizon Mode freezing
- 4. Generation of Perturbations Comoving horizon: Decelerating Expansion: Accelerating Expansion: Key ingredient for generation of perturbations: shrinking horizon
- 5. The Comoving Horizon in Inflation Decelerating Accelerating
- 7. Mode Exit and Reentry reentry classical exit quantum
- 10. The Horizon Is Not The Horizon The Hubble length is not the causal horizon in inflation. Mode freezing has absolutely nothing to do with causality.
- 11. The Horizon Is Not The Horizon In general, the Hubble length is not even the freezeout horizon: Scale invariance and freezeout:
- 12. Is Inflation the Only Way? Comoving Horizon (constant equation of state): Decelerating Expansion: Accelerating Expansion: Duality: (Boyle, et al., hepth/0403026)
- 13. The Comoving Hubble Horizon in Inflation Decelerating Accelerating
- 14. The Comoving Hubble Horizon in Bouncing Cosmology Expansion Bounce Contraction
- 15. The Cyclic Dual to Slow Roll Slow Roll
- 16. The Cyclic Dual to Slow Roll Slow Roll
- 17. The Cyclic Dual to Slow Roll Slow Roll DualSlow Roll Quasistatic contraction
- 18. Perturbations Slow Roll DualSlow Roll (WHK, Moradinezhad Dizgah, arXiv:1007.0753)
- 19. Ekpyrosis: Problems Shrinking proper Hubble length: blue spectra Instabilities: growing mode Negative potential Singular bounce Name sounds like a skin disease Buchbinder, Khoury & Ovru, PRD 76, 123503 (2007) Khoury & Steinhardt, arXiv:0910.2230 Linde, Mukhanov & Vikman, arXiv:0912.0944
- 20. Generating Superhorizon Perturbations New result: In an expanding universe, to generate perturbations consistent with observation, you must have one of: (1) Accelerated Expansion (2) Superluminal Sound Speed (3) SuperPlanckian Energy Density (Geshnizjani, WHK, Moradinezhad Dizgah, arXiv:1107.1241)
- 21. NonCanonical Lagrangians as Bimetric Theories Lagrangian with arbitrary kinetic term: Acoustic metric Light cone: Two horizons! Acoustic cone:
- 22. Light Cones in DBI Inflation Acoustic Cone: Light cone: x y
- 23. Mode Freezing and Horizons Tensor modes freeze out at the Hubble Horizon Scalar modes freeze out at the Acoustic Horizon Curvature perturbations generated by shrinking acoustic horizon! (Garriga & Mukhanov, arXiv:hepth/9904176)
- 24. Horizons in DBI Inflation Hubble Horizon Acoustic Horizon
- 25. Beyond Inflation For we still need inflation to generate superhorizon perturbations. Tachyacoustic Cosmology : generate superhorizon perturbations in a radiation or matterdominated universe ArmendarizPicon, arXiv:astroph/0606168 Piao, arXiv:grqc/0609071 Magueijo, arXiv:08030859 Bessada, WHK, Stojkovic, Wang, arXiv:0908.3898 Causally selfconsistent cosmology: no timelike loops. Babichev, Mukhanov & Vikman, arXiv:0708.0561
- 26. Light Cones in Tachyacoustic Cosmology Acoustic Cone: Light cone: x y
- 27. The Tachyacoustic Solution Decelerating Expansion: Decaying Sound Speed:
- 28. Horizons in Tachyacoustic Cosmology Hubble Horizon: Acoustic Horizon: Hubble Horizon grows (no tensor modes!) Acoustic Horizon shrinks
- 29. Horizons in Tachyacoustic Cosmology Hubble Horizon Acoustic Horizon
- 30. Perturbations in Tachyacoustic Cosmology Hubble Horizon: Acoustic Horizon: (Magueijo, arXiv:0803.0859) (Bessada, WHK, Stojkovic, Wang, arXiv:0908.3898)
- 31. Tachyacoustic Cosmology: Problems String embedding problematic Does not solve flatness problem Initial singularity Is it a dynamical attractor? (Preliminary: yes)
- 32. Summary The Hubble length is not the horizon. Expanding universe: only three ways to get scale invariance for a sufficient range of superHubble perturbations: Accelerated expansion Superluminal sound speed Transplanckian energy density Nothing works nearly as well as inflation.