  It is widely believed that the standard model is a low energy effective
theory which may have higher dimensional non-renormalizable operators. The
existence of these new operators can lead to interesting dynamics for the
evolution of the universe, including the appearance of new vacuum states. If
the universe today exists in a false vacuum, there will be a non-zero
probability to tunnel to the true vacuum state of the universe. Should this
transition occur elsewhere in the universe, bubbles of true vacuum will
nucleate and expand outwards. Bubbles that nucleate in the hot dense plasma of
the early universe will feel a friction from the plasma that acts against the
expansion of the bubble, until the bubble eventually reaches a steady state
expansion. Unlike many bubble formation scenarios where the bubble wall
velocity rapidly approaches the speed of light, friction from the hot
primordial plasma can cause the expanding bubble wall to reach a terminal
velocity while gravity waves are free to propagate through the hot dense plasma
at the speed of light. We analyze the effects of friction on the spectrum of
gravity waves caused by bubble collisions. We find that a phase transition in a
model with $\phi^6$ and $\phi^8$ operators that proceeds via a detonation in
the hot plasma of the early universe is unlikely. In the case of a
deflagration, the gravity wave spectrum is small and would likely require a
post-LISA experiment such as the Big Bang Observer, but is in principle,
observable.
