  The ostwald ripening of bubbles is studied by molecular dynamics simulations
involving up to 679 million Lennard-Jones particles. Many bubbles appear after
depressurizing a system that is initially maintained in the pure-liquid phase,
and the coarsening of bubbles follows. The self-similarity of the bubble-size
distribution function predicted by Lifshitz-Slyozov-Wagner theory is directly
confirmed. The total number of bubbles decreases asymptotically as $t^{-x}$
with scaling exponent $x$. As the initial temperature increases, the exponent
changes from $x=3/2$ to $1$, which implies that the growth of bubbles changes
from interface-limited (the $t^{1/2}$ law) to diffusion-limited (the $t^{1/3}$
law) growth.
