Some day my long run will come

Brad DeLong asks: At what time scale, if any, does the long run come?

Some other answers besides the 3-6 years discussed by Krugman and DeLong:

• It's already here in the IT model (we're back on trend, just not the trend you were thinking of [1], [2]). The time scale governing nominal shocks is really short; the time scale for unemployment is a bit longer (probably governed by matching theory).

• Never if the current state is defined by expectations at infinity (unless we change them). This (oddly) encompasses the liquidity trap and neo-Fisher views.

• Whenever the central bank really wants it to come (Green Lantern theory).