FAILURE OF STANDARD CONSERVATION-LAWS AT A CLASSICAL CHANGE OF SIGNATURE

The divergence theorem as usually stated cannot be applied across a ch ange of signature unless it is reexpressed to allow for a finite sourc e term on the signature change surface. Consequently all conservation laws must also be ''modified,'' and therefore insistence on conservati on of matter across such a surface cannot be physically justified. The Darmois junction conditions normally ensure conservation of matter vi a Israel's identities for the jump in the energy-momentum density, but not when the signature changes. Modified identities are derived for t his jump when a signature change occurs, and the resulting surface eff ects in the conservation laws are calculated. In general, physical vec tor fields experience a jump in at least one component, and a source t erm may therefore appear in the corresponding conservation law. Thus c urrent is also not conserved. These surface effects are a consequence of the change in the character of physical law. The only way to recove r standard conservation laws is to impose restrictions that no realist ic cosmological model can satisfy.