  We derive the rate for transitions between de Sitter vacua by treating the
field theory on the static patch as a thermal system. This reproduces the
Coleman-De Luccia formalism for calculating the rate, but leads to a modified
interpretation of the bounce solution and a different prediction for the
evolution of the system after tunneling. The bounce is seen to correspond to a
sequence of configurations interpolating between initial and final
configurations on either side of the tunneling barrier, all of which are
restricted to the static patch. The final configuration, which gives the
initial data on the static patch for evolution after tunneling, is obtained
from one half of a slice through the center of the bounce, while the other half
gives the configuration before tunneling. The formalism makes no statement
about the fields beyond the horizon.
  This approach resolves several puzzling aspects and interpretational issues
concerning the Coleman-De Luccia and Hawking-Moss bounces. We work in the limit
where the back reaction of matter on metric can be ignored, but argue that the
qualitative aspects remain in the more general case. The extension to tunneling
between anti-de Sitter vacua is discussed.
