# The Real No-Boundary Wave Function in Lorentzian Quantum Cosmology

## TL;DR

This paper demonstrates that the no-boundary wave function can be naturally expressed through a Lorentzian path integral using Picard-Lefschetz theory, predicting classical, inflationary universes with Gaussian fluctuations.

## Contribution

It introduces a Lorentzian path integral formulation of the no-boundary wave function, providing a real solution satisfying the Wheeler-DeWitt equation.

## Key findings

- Wave function is real and satisfies the Wheeler-DeWitt equation.
- Predicts an ensemble of classical, inflationary universes.
- Universes exhibit nearly-Gaussian fluctuations.

## Abstract

It is shown that the standard no-boundary wave function has a natural expression in terms of a Lorentzian path integral with its contour defined by Picard-Lefschetz theory. The wave function is real, satisfies the Wheeler-DeWitt equation and predicts an ensemble of asymptotically classical, inflationary universes with nearly-Gaussian fluctuations and with a smooth semiclassical origin.