  A significant fraction of the hot Jupiters with final circularized orbital
periods of less than 5 days are thought to form through the channel of
high-eccentricity migration. Tidal dissipation at successive periastron
passages removes orbital energy of the planet, which has the potential for
changes in semi-major axis of a factor of ten to a thousand. In the equilibrium
tide approximation we show that, in order for high-eccentricity migration to
take place, the relative level of tidal dissipation in Jupiter analogues must
be at least 10 times higher than the upper-limit attributed to the Jupiter-Io
interaction. While this is not a severe problem for high-e migration, it
contradicts the results of several previous calculations. We show that these
calculations of high-e migration inadvertently over-estimated the strength of
tidal dissipation by three to four orders of magnitude. These discrepancies
were obscured by the use of various parameters, such as lag time \tau, tidal
quality factor Q and viscous time t_V. We provide the values of these
parameters required for the Jupiter-Io interaction, tidal circularization and
high-e migration. Implications for tidal theory as well as models of the
inflated radii of hot Jupiters are discussed. Though the tidal Q is not, in
general, well-defined, we derive a formula for it during high-eccentricity
migration where Q is approximately constant throughout evolution.
