Membranes in the Kaluza-Klein theory

In the context of multidimensional theories with the extra dimensions extended and noncompact, we address the question of why the extra directions are not perceived. We show that the supplementary directions can be rendered unobservable if our four-dimensional world is considered a null membrane moving in D>4 dimensions. While a pure null membrane meets with some difficulties, a timelike membrane which becomes asymptotically null fits all our requirements