  In a classically scale-invariant quantum field theory, tunneling rates are
infrared divergent due to the existence of instantons of any size. While one
expects such divergences to be resolved by quantum effects, it has been unclear
how higher-loop corrections can resolve a problem appearing already at one
loop. With a careful power counting, we uncover a series of loop contributions
that dominate over the one-loop result and sum all the necessary terms. We also
clarify previously incomplete treatments of related issues pertaining to global
symmetries, gauge fixing and finite mass effects. In addition, we produce exact
closed-form solutions for the functional determinants over scalars, fermions
and vector bosons around the scale-invariant bounce, demonstrating manifest
gauge invariance in the vector case.
  With these problems solved, we produce the first complete calculation of the
lifetime of our universe: 10^139 years. With 95% confidence, we expect our
universe to last more than 10^58 years. The uncertainty is part experimental
uncertainty on the top quark mass and on ${\alpha}s$ and part theory
uncertainty from electroweak threshold corrections. Using our complete result,
we provide phase diagrams in the $mt/mh$ and the $mt/{\alpha}s$ planes, with
uncertainty bands. To rule out absolute stability to $3{\sigma}$ confidence,
the uncertainty on the top quark pole mass would have to be pushed below 250
MeV or the uncertainty on ${\alpha}s(mZ)$ pushed below 0.00025.
