  Hamilton's principle does not formally apply to systems whose boundary
conditions lie outside configuration space, but extensions are possible using
certain "natural" boundary conditions that allow action extremization. With the
single conjecture that only such action-extremizing boundaries can be
physically realized, the classical relativistic scalar field becomes subject to
certain quantization conditions upon measurement. These conditions appear to be
analogous to Bohr-Sommerfeld quantization, and are derived explicitly for the
case of angular momentum measurements of a classical scalar field.
