The distribution of Omega_k from the scale-factor cutoff measure

  title={The distribution of Omega\_k from the scale-factor cutoff measure},
  author={Andrea De Simone and Michael P. Salem},
  journal={Physical Review D},
Our universe may be contained in one among a diverging number of bubbles that nucleate within an eternally inflating multiverse. A promising measure to regulate the diverging spacetime volume of such a multiverse is the scale-factor cutoff, one feature of which is bubbles are not rewarded for having a longer duration of slow-roll inflation. Thus, depending on the landscape distribution of the number of e-folds of inflation among bubbles like ours, we might hope to measure spacetime curvature… 

Figures from this paper

New scale factor measure
The computation of probabilities in an eternally inflating universe requires a regulator or ``measure.'' The scale factor time measure truncates the Universe when a congruence of timelike geodesics
Four-volume cutoff measure of the multiverse
Predictions in an eternally inflating multiverse are meaningless unless we specify the probability measure. The scale-factor cutoff is perhaps the simplest and most successful measure which avoid
What can the observation of nonzero curvature tell us
The eternally inflating multiverse provides a consistent framework to understand coincidences and fine-tuning in the universe. As such, it provides the possibility of finding another coincidence: if
Observable effects of anisotropic bubble nucleation
Our universe may have formed via bubble nucleation in an eternally-inflating background. Furthermore, the background may have a compact dimension — the modulus of which tunnels out of a metastable
Geometric origin of coincidences and hierarchies in the landscape
We show that the geometry of cutoffs on eternal inflation strongly constrains predictions for the time scales of vacuum domination, curvature domination, and observation. We consider three measure
Accidental Inflation in the Landscape
We study some aspects of fine tuning in inflationary scenarios within string theory flux compactifications and, in particular, in models of accidental inflation. We investigate the possibility that
Phenomenology of the CAH+ measure
The CAH+ measure regulates the infinite spacetime volume of the multiverse by constructing a surface of constant comoving apparent horizon (CAH) and then removing the future lightcones of all points
Bubble collisions and measures of the multiverse
To compute the spectrum of bubble collisions seen by an observer in an eternally-inflating multiverse, one must choose a measure over the diverging spacetime volume, including choosing an "initial"
Spacetime Average Density (SAD) Cosmological Measures
The measure problem of cosmology is how to obtain normalized probabilities of observations from the quantum state of the universe. This is particularly a problem when eternal inflation leads to a


Predicting the cosmological constant with the scale-factor cutoff measure
It is well known that anthropic selection from a landscape with a flat prior distribution of cosmological constant {lambda} gives a reasonable fit to observation. However, a realistic model of the
Taming the Runaway Problem of Inflationary Landscapes
A wide variety of vacua, and their cosmological realization, may provide an explanation for the apparently anthropic choices of some parameters of particle physics and cosmology. If the probability
Boltzmann brains and the scale-factor cutoff measure of the multiverse
To make predictions for an eternally inflating 'multiverse', one must adopt a procedure for regulating its divergent spacetime volume. Recently, a new test of such spacetime measures has emerged:
Density perturbations and the cosmological constant from inflationary landscapes
An anthropic understanding of the cosmological constant requires that the vacuum energy at late time scans from one patch of the universe to another. If the vacuum energy during inflation also scans,
Density parameter and the anthropic principle
In the context of open inflation, we calculate the probability distribution for the density parameter $\Omega$. A large class of two field models of open inflation do not lead to infinite open
Probability distribution for omega in open universe inflation
The problem of making predictions in eternally inflating universe that thermalizes by bubble nucleation is considered. A recently introduced regularization procedure is applied to find the
Observational consequences of a landscape
In this paper we consider the implications of the ``landscape paradigm [1], [2] for the large scale properties of the universe. The most direct implication of a rich landscape is that our local
The cosmic variance of Omega
How much can we know about our Universe? All of our observations are restricted to a finite volume, and therefore our estimates of presumably global cosmological parameters are necessarily based on
Scale of gravity and the cosmological constant within a landscape
It is possible that the scale of gravity, parametrized by the apparent Planck mass, may obtain different values within different universes in an encompassing multiverse. We investigate the range over
Properties of the scale factor measure
We show that in expanding regions, the scale factor measure can be reformulated as a local measure: Observations are weighted by integrating their physical density along a geodesic that starts in the