Emergence of life in an inflationary universe
  Abiotic emergence of ordered information stored in the form of RNA is an
important unresolved problem concerning the origin of life. A polymer longer
than 40--100 nucleotides is necessary to expect a self-replicating activity,
but the formation of such a long polymer having a correct nucleotide sequence
by random reactions seems statistically unlikely. However, our universe,
created by a single inflation event, likely includes more than $10^{100}$
Sun-like stars. If life can emerge at least once in such a large volume, it is
not in contradiction with our observations of life on Earth, even if the
expected number of abiogenesis events is negligibly small within the observable
universe that contains only $10^{22}$ stars. Here, a quantitative relation is
derived between the minimum RNA length $l_{\min}$ required to be the first
biological polymer, and the universe size necessary to expect the formation of
such a long and active RNA by randomly adding monomers. It is then shown that
an active RNA can indeed be produced somewhere in an inflationary universe,
giving a solution to the abiotic polymerization problem. On the other hand,
$l_{\min}$ must be shorter than $\sim$20 nucleotides for the abiogenesis
probability close to unity on a terrestrial planet, but a self-replicating
activity is not expected for such a short RNA. Therefore, if extraterrestrial
organisms of a different origin from those on Earth are discovered in the
future, it would imply an unknown mechanism at work to polymerize nucleotides
much faster than random statistical processes.
