we have outlined the main consequences of 5D relativity with signature [+(−−− )+]. Though technically referred to as “two-time” metrics, there is no problem with closed timelike paths because the second timelike coordinate is related to the (inertial) rest mass of a particle in both induced-matter and membrane theory [2,7]. To derive physical results requires the specification of a gauge, as in (1) or (2). However, we have given the components of the 5D Ricci tensor RAB for a general non-electromagneticgauge in (3)–(5). These for field equations RAB =0 lead to expressions for the embedded 4D Einstein space, namely (6) for the curvature scalar and (7) for the energy–momentum tensor. The exact solution (8) illustrates the new physics derivable from two-time metrics: it describes a wave moving through a de Sitter vacuum. The general twotime metrics (9) describe waves in the fifth dimension that oscillate around the hypersurface we call spacetime. This can be used as a model for multiply-imaged particles. The dynamics of the latter are governed by relations (10)–(12), which show that the fifth force typical of induced-matter and membrane theory is absent if the weak equivalence principle is invoked as a symmetry of the metric.