A coherent approach to Spacetime Foam

A coherent superposition of N Schwarzschild wormholes is proposed as a model for spacetime foam. Following the subtraction procedure for manifolds with boundaries, we calculate by variational methods the Casimir energy. A proposal for an alternative foamy model formed by N Schwarzschild-Anti-de Sitter wormholes is here considered. Finally, a conjecture about the foam evolution is proposed.Comment: 3 pages. To be submitted to the proceedings of the 3rd Workshop of `Mysteries, Puzzles And Paradoxes In Quantum Mechanics' Gargnano (Italy), 17-23 September 200