  For the first time, we investigate the non-perturbative dynamics of single
field inflation with a departure from slow-roll. Using simulations, we find
that oscillatory features in the potential can drastically alter the course of
inflation, with major phenomenological implications. In certain cases, the
entire Universe gets trapped in a forever inflating de Sitter state. In others,
only some regions get stuck in a false vacuum, offering an alternative channel
for primordial black hole formation. Analogous to the flap of a butterfly,
these results show that small-scale phenomena can have profound consequences on
the evolution of the entire Universe. This demonstrates the necessity of a
non-perturbative approach in the exploration of the small-scale physics of
inflation, particularly in the regime relevant for gravitational-wave
astronomy.
