ABSTRACT
Thus we have a "fast mode" q with a shorter relaxation
time and a "slow m ode" q with a longer one. These
simple results illustrate the important role of the mode-
mode coupling term s v^ in (11.4).
4. ELIM INATION OF FAST MODES
In our study of static cr it ica l phenomena, the e l im i-
nation of short-wavelength modes played an important part,
especially in the renormalization group. In critica l dynam-
ics, we are concerned mainly with modes with long re laxa-
tion times. The elimination of modes with short relaxation
times w ill again play an important part. In statics, the
elimination was effected by integrating out the unwanted
modes in the probability distribution. In dynamics, the
elimination process is effected very differently. As a
simple illustration, let us return to the harmonic oscillator
equations.
