Measure Problem for Eternal and Non-Eternal Inflation

  title={Measure Problem for Eternal and Non-Eternal Inflation},
  author={Andrei Linde and Mahdiyar Noorbala},
  journal={arXiv: High Energy Physics - Theory},
We study various probability measures for eternal inflation by applying their regularization prescriptions to models where inflation is not eternal. For simplicity we work with a toy model describing inflation that can interpolate between eternal and non-eternal inflation by continuous variation of a parameter. We investigate whether the predictions of four different measures (proper time, scale factor cutoff, stationary and causal {diamond}) change continuously with the change of this… 

Figures and Tables from this paper

The End of Eternal Inflation
We propose a new measure for eternal inflation that includes both conditions, large field fluctuations and smooth homogeneous domains, in the self reproducing probability estimate. We show that due
Dynamical systems of eternal inflation: a possible solution to the problems of entropy, measure, observables and initial conditions
There are two main approaches to non-equlibrium statistical mechanics: one using stochastic processes and the other using dynamical systems. To model the dynamics during inflation one usually adopts
Primordial perturbations from string inflation
In this work we explore the correspondence between the physical processes associated with inflationary models inspired by string theory and the subsequent non-Gaussian signatures imprinted in the
Stochastic ultra slow roll inflation
We study the ultra slow roll model in the context of stochastic inflation. Using stochastic $\delta N$ formalism, we calculate the mean number of $e$-folds, the power spectrum, the bispectrum and the
Exploring a string-like landscape
We explore inflationary trajectories within randomly-generated two-dimensional potentials, considered as a toy model of the string landscape. Both the background and perturbation equations are solved
An introduction to inflation after Planck: from theory to observations
These lecture notes have been written for a short introductory course on the status of inflation after Planck and BICEP2, given at the Xth Modave School of Mathematical Physics. The first objective
Agnesi weighting for the measure problem of cosmology
The measure problem of cosmology is how to assign normalized probabilities to observations in a universe so large that it may have many observations occurring at many different spacetime locations. I
Volume weighting the measure of the universe from classical slow-roll expansion
One of the most frustrating issues in early universe cosmology centers on how to reconcile the vast choice of universes in string theory and in its most plausible high energy sibling, eternal
Tensor modes on the string theory landscape
A bstractWe attempt an estimate for the distribution of the tensor mode fraction r over the landscape of vacua in string theory. The dynamics of eternal inflation and quantum tunneling lead to a kind
How unitary cosmology generalizes thermodynamics and solves the inflationary entropy problem
We analyze cosmology assuming unitary quantum mechanics, using a tripartite partition into system, observer, and environment degrees of freedom. This generalizes the second law of thermodynamics to


Eternal inflation and its implications
I summarize the arguments that strongly suggest that our universe is the product of inflation. The mechanisms that lead to eternal inflation in both new and chaotic models are described. Although the
Stationarity of inflation and predictions of quantum cosmology.
A new mechanism is proposed which may help solve the cosmological constant problem and is given examples of models where each of these possibilities can be realized, and some implications for quantum cosmology are discussed.
Holographic probabilities in eternal inflation.
It is proposed to estimate the probability for observers to emerge in a given vacuum by the entropy that can be produced in a local patch, which allows for prior-free predictions.
Predictions in eternal inflation
In generic models of cosmological inflation, quantum fluctuations strongly influence the spacetime metric and produce infinitely many regions where the end of inflation (reheating) is delayed until
The dynamics of a large-scale quasi-homogeneous scalar field producing the de Sitter (inflationary) stage in the early universe is strongly affected by small-scale quantum fluctuations of the same
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
Fluctuations of the gravitational constant in the inflationary Brans-Dicke cosmology.
It is found that in some inflationary models the probability distribution P_p rapidly approaches a stationary regime, and the shape of the distribution depends, however, on the choice of the time parametrization.
Anthropic Prediction for Λ and the Q Catastrophe
We discuss probability distributions for the cosmological constant A and the amplitude of primordial density fluctuations Q in models where they both are anthropic variables. With mild assumptions
What does inflation really predict
If the inflaton potential has multiple minima, as may be expected in, e.g., the string theory 'landscape', inflation predicts a probability distribution for the cosmological parameters describing
Recycling universe
If the effective cosmological constant is non-zero, our observable universe may enter a stage of exponential expansion. In such case, regions of it may tunnel back to the false vacuum of an inflaton