ABSTRACT
The fact that microscopic details seem to make very little
difference in crit ica l phenomena strongly suggests that the
observed general pattern should be interpetable as sym-
metry properties, even though it is not clear a priori what
the desired symmetry transformations are*
There has been some success in constructing the
desired transformations, although nothing as neat and
simple as the rotation group has been obtained. We shall
call the desired transformations the renormalization group,
abbreviated as the RG, There is no obvious motivation for
this name, but we shall see some justification for it at a
technical leve l later. There are many features of the RG
not shared by the familiar symmetry transformations. Its
application is not as simple as we suggested above. For
example, a system at a cr it ica l point w ill not be simply
invariant under the RG but w i l l have certain special
p roperties .
