  Light nuclei fall within a regime of universal physics governed by the fact
that the two-nucleon scattering lengths are large compared to the typical
nuclear interaction range set by one-pion exchange. This places nuclear physics
near the so-called unitarity limit in which the scattering lengths are exactly
infinite. Effective field theory provides a powerful theoretical framework to
capture this separation of scales in a systematic way. It is shown here that
the nuclear force can be constructed as a perturbative expansion around the
unitarity limit and that this expansion has good convergence properties for
both the binding energies of $A=3,4$ nuclei as well as for the radii of these
states.
