Multiverse Predictions for Habitability: Fraction of Planets that
  Develop Life
  In a multiverse context, determining the probability of being in our
particular universe depends on estimating its overall habitability compared to
other universes with different values of the fundamental constants. One of the
most important factors in determining this is the fraction of planets that
actually develop life, and how this depends on planetary conditions. Many
proposed possibilities for this are incompatible with the multiverse: if the
emergence of life depends on the lifetime of its host star, the size of the
habitable planet, or the amount of material processed, the chances of being in
our universe would be very low. If the emergence of life depends on the entropy
absorbed by the planet, however, our position in this universe is very natural.
Several proposed models for the subsequent development of life, including the
hard step model and several planetary oxygenation models, are also shown to be
incompatible with the multiverse. If any of these are observed to play a large
role in determining the distribution of life throughout our universe,
the~multiverse hypothesis will be ruled out to high significance.
