  We construct a configurational entropy measure in functional space. We apply
it to several nonlinear scalar field models featuring solutions with
spatially-localized energy, including solitons and bounces in one spatial
dimension, and critical bubbles in three spatial dimensions, typical of
first-order phase transitions. Such field models are of widespread interest in
many areas of physics, from high energy and cosmology to condensed matter.
Using a variational approach, we show that the higher the energy of a trial
function that approximates the actual solution, the higher its relative
configurational entropy, defined as the absolute difference between the
configurational entropy of the actual solution and of the trial function.
Furthermore, we show that when different trial functions have degenerate
energies, the configurational entropy can be used to select the best fit to the
actual solution. The configurational entropy relates the dynamical and
informational content of physical models with localized energy configurations.
