Investigation of the selection of original universe proposal

2006

Phys. Rev. D

Self Cite

We show that the inclusion of backreaction of massive long wavelengths imposes dynamical constraints on the allowed phase space of initial conditions for inflation, which results in a superselection rule for the initial conditions. Only high energy inflation is stable against collapse due to the gravitational instability of massive perturbations. We present arguments to the effect that the initial conditions problem cannot be meaningfully addressed by thermostatistics as far as the gravitational degrees of freedom are concerned. Rather, the choice of the initial conditions for the universe in the phase space and the emergence of an arrow of time have to be treated as a dynamic selection.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Why the Universe started from a low entropy state

Holman

2006

Phys. Rev. D

Self Cite

“…Backreaction shifts the energy of the wavepacket therefore its classical trajectory on the landscape. The shifting of the classical path for our wavefunction can be seen by integrating out the Master Equation presented for this case as was described in [8,10,12].…”

Section: Motivating the Class Of Oscillating Curvature Modelsmentioning

confidence: 99%

“…This model is inspired and motivated from the proposal for a dynamic selection of the initial conditions for our universe from the landscape phase space [8,9] as summarized below.…”

Section: Motivating the Class Of Oscillating Curvature Modelsmentioning

confidence: 99%

See 1 more Smart Citation

Nontrivial geometries: Bounds on the curvature of the universe

Kafexhiu

2008

Astroparticle Physics

Self Cite

Probing the geometry of the universe is one of the most important endevours in cosmology. Current observational data from the Cosmic Microwave Background anisotropy (CMB), galaxy surveys and type Ia supernovae (SNe Ia) strongly constrain the curvature of the universe to be close to zero for a universe dominated by a cosmological constant or dark energy with a constant equation of state. Here we investigate the role of cosmic priors on deriving these tight bounds on geometry, by considering a landscape motivated scenario with an oscillating curvature term. We perform a likelihood analysis of current data under such a model of non-trivial geometry and find that the uncertainties on curvature, and correspondingly on parameters of the matter and dark energy sectors, are larger. Future dark energy experiments together with CMB data from experiments like Planck could dramatically improve our ability to constrain cosmic curvature under such models enabling us to probe possible imprints of quantum gravity.

The Arrow of Time In a Universe with a Positive Cosmological Constant Λ

2011

Cosmic Update

Motivated by the mounting evidence for dark energy, here we explore the consequences of a fundamental cosmological constant Λ for our universe. We show that when the gravitational entropy of a pure DeSitter state ultimately wins over matter, then the thermodynamic arrow of time in our universe must reverse in scales of order a Hubble time. We find that due to the dynamics of gravity and nonlocal entanglement, a finite size system such as a DeSitter patch with horizon size H −1 0 has a finite lifetime ∆t. This phenomenon arises from the dynamic gravitational instabilities that develop during a DeSitter epoch and turn catastrophic. A reversed arrow of time is clearly in disagreement with observations. Thus we are led to conclude: Nature forbids a fundamental Λ. Or else general relativity must be modified in the IR regime when Λ dominates the expansion of the Universe.