# Multiverse Predictions for Habitability: Planetary Characteristics

## TL;DR

This paper explores how the multiverse hypothesis influences planetary habitability predictions, evaluating various criteria and mechanisms to identify which are favored or disfavored under multiverse assumptions.

## Contribution

It systematically assesses habitability factors within the multiverse framework, providing novel predictions and constraints on planetary features and water delivery mechanisms.

## Key findings

- Large moons are not necessary for habitability in the multiverse.
- Some water delivery mechanisms are strongly disfavored by multiverse-based Bayesian analysis.
- Multiverse considerations can significantly alter habitability predictions.

## Abstract

Recent detections of potentially habitable exoplanets around sunlike stars demand increased exploration of the physical conditions that can sustain life, by whatever methods available. Insight into these conditions can be gained by considering the multiverse hypothesis; in a multiverse setting, the probability of living in our universe depends on assumptions made about the factors affecting habitability. Various proposed habitability criteria can be systematically considered to rate each on the basis of their compatibility with the multiverse, generating predictions which can both guide expectations for life's occurrence and test the multiverse hypothesis. Here, we evaluate several aspects of planetary habitability, and show that the multiverse does indeed induce strong preferences among them. We find that the notion that a large moon is necessary for habitability is untenable in the multiverse scenario, as in the majority of parameter space, moons are not necessary to maintain stable obliquity. Further, we consider various proposed mechanisms for water delivery to the early Earth, including delivery from asteroids, both during giant planet formation and a grand tack, delivery from comets, and oxidation of a primary atmosphere by a magma ocean. We find that, depending on assumptions for how habitability depends on water content, some of these proposed mechanisms are disfavored in the multiverse scenario by Bayes factors of up to several hundred.