  In the context of a homogeneous universe, we note that the appearance of
aggressively expanding advanced life is geometrically similar to the process of
nucleation and bubble growth in a first-order cosmological phase transition. We
exploit this similarity to describe the dynamics of life saturating the
universe on a cosmic scale, adapting the phase transition model to incorporate
probability distributions of expansion and resource consumption strategies.
Through a series of numerical solutions spanning several orders of magnitude in
the input assumption parameters, the resulting cosmological model is used to
address basic questions related to the intergalactic spreading of life, dealing
with issues such as timescales, observability, competition between strategies,
and first-mover advantage. Finally, we examine physical effects on the universe
itself, such as reheating and the backreaction on the evolution of the scale
factor, if such life is able to control and convert a significant fraction of
the available pressureless matter into radiation. We conclude that the
existence of life, if certain advanced technologies are practical, could have a
significant influence on the future large-scale evolution of the universe.
