A note on 4-dimensional traversable wormholes and energy conditions in higher dimensions

We show explicitly that traversable wormholes requiring exotic matter in 4-dimensions nevertheless have acceptable stress-tensors obeying reasonable energy conditions in higher dimensions if the wormholes are regarded as being embedded in higher dimensional space-times satisfying Einstein's field equations. From the 4-dimensional perspective, the existence of higher dimensions may thus facilitate wormhole and time-machine constructions through access to "exotic matter".