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Challenges for Early Universe Cosmology - 2011

Challenges for Early Universe Cosmology

 

Mercredi juil 13, 2011
Speaker(s): 

Inflationary cosmology not only provided a simple solution to various cosmological problems, but also made predictions later confirmed by observations. Despite of its success, a straightforward extrapolation of the theory to higher energy scales led to new problems and seems to require new physics. In this talk I review the new problems, discuss their possible resolutions and speculate on possible predictions of the new physics.

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Mercredi juil 13, 2011

I will introduce a simple 6d model of flux compactification that shows a remarkable rich landscape of vacua with different number of large and compact dimensions. I will then describe the instantons interpolating between these different vacua as well as some the implications of a transdimensional multiverse of this form.

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Mercredi juil 13, 2011
Speaker(s): 

In its best understood version, the Steinhardt-Turok cyclic universe contains two crucial ingredients: an unstable field trajectory during the ekpyrotic phase, and the subsequent brane collision corresponding to the crunch/bang transition. These two features act as strong selection principles and determine the broad physical properties of the universe emerging from the bang. As such, they significantly alleviate (and perhaps resolve) the measure problem that is inherent to all cosmological models that produce universes with a range of physical properties.

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Mercredi juil 13, 2011
Speaker(s): 

If the universe is a quantum mechanical system it has a quantum state.
This state supplies a probabilistic measure for alternative histories of the universe. During eternal inflation these histories typically develop large inhomogeneities that lead to a mosaic structure on superhorizon scales consisting of homogeneous patches separated by inflating regions.

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Mardi juil 12, 2011
Speaker(s): 

In this talk, I will describe how the collision of Minkowski or crunching bubbles can re-start inflation in a portion of the bubble interior. Consistent with various singularity theorems, such collisions can only seed a lasting inflationary phase with energy density lower than that of the parent vacuum.

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Mardi juil 12, 2011
Speaker(s): 

The eternal inflation scenario predicts that our observable universe resides inside a single bubble embedded in a vast inflating multiverse. Collisions between bubble universes imprinted in the CMB sky provide a powerful observational test of this idea. I will describe a robust algorithm for non-Gaussian source detection in massive datasets, and present its application to the search for bubble collision signatures in CMB data from WMAP.

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