Predicting a Prior for Planck

TL;DR

This paper calculates the prior for CMB observables using the no-boundary wave function in a landscape model, showing predictions align with Planck data and disfavoring high-potential inflation scenarios.

Contribution

It provides a novel computation of the prior for cosmological observations based on the no-boundary wave function within a landscape framework.

Findings

Primordial spectra match Planck data for concave potentials

High-potential inflation scenarios are disfavored

Classical cosmology emerges from eternal inflation regions

Abstract

The quantum state of the universe combined with the structure of the landscape potential implies a prior that specifies predictions for observations. We compute the prior for CMB related observables given by the no-boundary wave function (NBWF) in a landscape model that includes a range of inflationary patches representative of relatively simple single-field models. In this landscape the NBWF predicts our classical cosmological background emerges from a region of eternal inflation associated with a plateau-like potential. The spectra of primordial fluctuations on observable scales are characteristic of concave potentials, in excellent agreement with the Planck data. By contrast, alternative theories of initial conditions that strongly favor inflation at high values of the potential are disfavored by observations in this landscape.