1. The Cosmological Slingshot Scenario A Stringy Proposal for Early Time Cosmology: Germani, NEG, Kehagias, hep-th/0611246 Germani, NEG, Kehagias, arXiv:0706.0023 Germani, Ligouri, arXiv:0706.0025 Germani, NEG, Kehagias, hep-th/0611246 Germani, NEG, Kehagias, arXiv:0706.0023 Germani, Ligouri, arXiv:0706.0025

2. What do we know about the universe? Standard cosmology It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small It is expanding It is accelerating The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum 4d metric WMAP collaboration astro-ph/0603449

3. Standard cosmology It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small It is expanding It is accelerating The space is almost flat 4d metric Einstein equations Hubble equation Energy density Curvature term The perturbations around homogeneity have a flat (slightly red) spectrum

4. Standard cosmology It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small It is expanding It is accelerating The space is almost flat 4d metric Hubble equation toto a  t  Plank t Plank Big Bang Solution The perturbations around homogeneity have a flat (slightly red) spectrum

5. Standard cosmology It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small It is expanding It is accelerating The space is almost flat toto t t Plank The perturbations around homogeneity have a flat (slightly red) spectrum  is constant in the observable region of 10 28 cm Causally disconnected regions are in equilibrium!

6. Standard cosmology It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small It is expanding It is accelerating The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum Isotropic solutions form a subset of measure zero on the set of all Bianchi solutions Perturbations around isotropy dominate at early time, like a -6, giving rise to chaotic behavior! Belinsky, Khalatnikov, Lifshitz, Adv. Phys. 19, 525 (1970) Belinsky, Khalatnikov, Lifshitz, Adv. Phys. 19, 525 (1970) Collins, Hawking Astr.Jour.180, (1973) Collins, Hawking Astr.Jour.180, (1973)

7. Standard cosmology It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small It is expanding It is accelerating The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum It is a growing function Since it is small today, it was even smaller at earlier time! (10 -8 at Nuc.)

8. Standard cosmology It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small It is expanding It is accelerating The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum What created perturbations? If they were created by primordial quantum fluctuations, its resulting spectrum for normal matter is not flat Their existence is necessary for the formation of structure (clusters, galaxies)

9. The perturbations around homogeneity have a flat (slightly red) spectrum  Plank t Plank Big Bang Solving to the problems Inflation  Plank Standard cosmology It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small It is expanding It is accelerating The space is almost flat t earlier < t Nuc  toto a t It is nearly homogeneous The space is almost flat It is nearly isotropic Guth, PRD 23, 347 (1981) Linde, PLB 108, 389 (1982) Guth, PRD 23, 347 (1981) Linde, PLB 108, 389 (1982)

10. The perturbations around homogeneity have a flat (slightly red) spectrum It is nearly isotropic The space is almost flat  Plank Bounce Standard cosmology It is nearly homogeneous The vacuum energy density is very small It is expanding It is accelerating The space is almost flat t earlier < t Nuc  toto a t Quantum regime It is nearly homogeneous

11.  Plank  toto a t Bounce  Plank  toto a t Inflation Standard cosmology It is nearly homogeneous It is nearly isotropic The vacuum energy density is very small It is expanding It is accelerating The space is almost flat The perturbations around homogeneity have a flat (slightly red) spectrum t earlier < t Nuc Quantum regime C a n t h e b o u n c e b e c l a s s i c a l ?

12. Mirage cosmology Higher dimensional bulk 4d flat slice 3-Brane Warping factor Matter Universe Cosmological evolution  Plank  toto a t t earlier Kehagias, Kiritsis hep-th/9910174 Kehagias, Kiritsis hep-th/9910174

13.  Plank t Plank Big Bang Mirage cosmology  toto a t t earlier Increasing warping Monotonous motion Expanding Universe How can we obtain a bounce? A minimum in the warping factor A turning point in the motion Solve Einstein equations Solve equations of motion

14. Slingshot cosmology 10d bulk IIB SUGRA solution 4d flat slice BPS Warping factor D3-Brane Cosmological expansion  Plank  toto a t t earlier XaüXaü x  || Germani, NEG, Kehagias hep-th/0611246

15. Slingshot cosmology XaüXaü x  ||  Plank  toto a t t earlier XaüXaü Dilaton fieldInduced metric RR field Turning point Bounce Burgess, Quevedo, Rabadan, Tasinato, Zavala, hep-th/0310122

16. 6d flat euclidean metric Warping factor Slingshot cosmology XaüXaü  Plank  toto a t t earlier XaüXaü Transverse metric AdS 5 xS 5 space Free particle Turning point Bounce Non-vanishing impact parameter Non-vanishing angular momentum l Heavy source Stack of branes Burgess, Martineau, Quevedo, Rabadan, hep-th/0303170 Burgess, NEG, F. Quevedo, Rabadan, hep-th/0310010 Burgess, Martineau, Quevedo, Rabadan, hep-th/0303170 Burgess, NEG, F. Quevedo, Rabadan, hep-th/0310010

17. Non-vanishing angular momentum l 6d flat Euclidean metric Slingshot cosmology XaüXaü  Plank  toto a t t earlier XaüXaü AdS 5 xS 5 space Free particle Heavy source Stack of branes There is no space curvature

18. Can we solve the flatness problem? Flatness problem is solved There is no space curvature Slingshot cosmology  Plank  toto a t t earlier Constraint in parameter space

19. Slingshot cosmology  Plank  toto a t t earlier What about isotropy? Dominates at early time, avoiding chaotic behaviour All the higher orders in r´ Isotropy problem is solved

20. Slingshot cosmology  Plank  toto a t t earlier And about perturbations?

21. Induced scalar Bardeen potential Slingshot cosmology  Plank  toto a t t earlier And about perturbations? Scalar field Harmonic oscillator Growing modes Oscilating modes Frozen modes Decaying modes Frozen modes survive up to late times Decaying modes do not survive Boehm, Steer, hep-th/0206147 Boehm, Steer, hep-th/0206147 Germani, NEG, Kehagias arXiv:0706.0023 Germani, NEG, Kehagias arXiv:0706.0023

22. Frozen modes Slingshot cosmology  Plank  toto a t t earlier Power spectrum = Created by quantum perturbations **

23. r   = kL  / l c Creation of the mode  = l c Creation of the mode Slingshot cosmology  Plank  toto a t t earlier Power spectrum **  > l c Classical mode  < l c Quantum mode Hollands, Wald gr-qc/0205058 Hollands, Wald gr-qc/0205058 = k  a  = kL / r We get a flat spectrum

24. Slingshot cosmology  Plank  toto a t t earlier Gravity is ten dimensional Late time cosmology Formation of structure Kepler laws Real life! Compactification AdS throat in a CY space AdS throat Top of the CY Mirage dominated era Local 4d gravity dominated era backreaction Mirage domination in the throat Local gravity domination in the top The transition is out of our control

25. Open Points The price we paid is an unknown transition region between local and mirage gravity (reheating) It is nearly isotropic The perturbations around homogeneity have a flat spectrum The space is almost flat Slingshot cosmology It is nearly homogeneous The vacuum energy density is very small It is expanding It is accelerating Nice Results Klevanov-Strassler geometry gives a slightly red spectral index, in agreement with WMAP Problems with Hollands and Wald proposal are avoided in the Slingshot scenario An effective 4D action can be found There is no effective 4D theory Back-reaction effects should be studied