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Published byElinor Welch Modified over 9 years ago
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Has inflation fulfilled its promise?
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the classical view the quantum view “ordering” “disordering”
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unpredictability problem Linde, Linde, Mezhlumian, PRD 50, 2456 (1994) persistence of memory problem geodesic incompleteness entropy problem transplanckian problem
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Either: - solve these problems, or - seek alternative models that avoid them Observers & experimentalists will help: - conduct tests that enable us to distinguish among inflation and its alternatives
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H smoothing > H normal >> H today 1) Inflation is fast 2) Quantum physics is random
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H smoothing << H normal Suppose Unpredictability Persistence of Memory Entropy Problem Singularity Problem ?
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How do we go from small H to large H ? a bounce i.e., confront the singularity rather than ignore it
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w ~ -1 Inflation: ultra-rapid expansion
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w w >> 1 N.B. Do not need finely tuned initial conditions or inflation or dark energy … ekpyrotic/cyclic: ultra-slow contraction Erickson, Wesley, PJS. Turok Erickson, Gratton, PJS, Turok
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w w >> 1 … and avoid chaotic mixmaster behavior … ekpyrotic/cyclic: slow contraction Erickson, Wesley, PJS. Turok Erickson, Gratton, PJS, Turok
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w w >> 1 … and makes scale-invariant perturbations of scalar fields … ekpyrotic/cyclic: slow contraction Erickson, Wesley, PJS. Turok Erickson, Gratton, PJS, Turok
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w w >> 1 … without encountering transplanckian fluctuations. ekpyrotic/cyclic: slow contraction Erickson, Wesley, PJS. Turok Erickson, Gratton, PJS, Turok
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V inflation ekpyrotic/cyclic V Khoury, PJS, Ovrut, Turok Buchbinder, Khoury, Ovrut
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“bang” radiation matter dark energy “ekpyrotic” contraction “crunch” How do we convert scalar field fluctuations into curvature perturbations?
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Entropic approach: two ordinary scalar fields and NO extra dimensions: entropic curvature Buchbinder, Khoury Ovrut, Creminelli and Senatore Koyama, Mizumo, Wands Wesley and Tolley, Finelli & Brandenberger Lehners, McFadden, Turok, and PJS AdS/CFT approach: (see Turok’s talk) Turok, Craps, Hertog
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Gravitational waves? Non-gaussian fluctuations?
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Gravitational waves? Non-gaussian fluctuations? Primordial amplitude proportional to H smoothing 2
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from Baumann, PJS, Takahashi, Ichiki see also Mollerach, Harari, Mattarese Ananda, Clarkson, Wands
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Gravitational waves? Non-gaussian fluctuations?
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Buchbinder, Khoury Ovrut, arXiv:0706.3903 Creminelli and Senatore, hep-th/0702165 Koyama, Mizumo, Wands, to appear Entropic mechanism can produce significant non-gaussianity: (WMAP team) (Yadav & Wandelt) compatible for w < 30 conversion during ekpyrotic phase
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J-L. Lehners & PJS Entropic mechanism can produce significant non-gaussianity: (WMAP team) conversion after ekpyrotic phase compatible for w < 3000 and with tilt (Yadav & Wandelt)
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(WMAP team) (Yadav & Wandelt)
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