Multiverse Predictions for Habitability: Planetary Characteristics

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.

Automated summary

Recent discoveries of potentially habitable exoplanets around sunlike stars have prompted increased exploration of the physical conditions necessary for life. By considering the multiverse hypothesis, researchers can evaluate various habitability criteria and their compatibility with the existence of multiple universes, providing guidance for the search for extraterrestrial life and testing the multiverse hypothesis. This study examines different aspects of planetary habitability and demonstrates that the multiverse strongly influences these aspects, challenging previous assumptions about the necessity of a large moon for habitability and favoring certain mechanisms for water delivery to early Earth.