Alberto said: > Stable Macroscopic Wormholes violate _causality_.
Stable macroscopic wormholes can certainly be used to violate causality, yes. However, not all configurations of such wormholes do. Furthermore, it may be that wormholes become unstable as they approach causality violation. I think that, roughly speaking, you're okay as long as the mouths move away from each other. However, there are various theorems in GR that say that a change in topology (for example, the production of a wormhole) necessarily leads to the production of closed timelike curves. We'll be okay if there are primordial microscopic wormholes that we can blow up though. Or perhaps we'll be able to contain the CTCs behind event horizons somehow - after all, there are black hole geometries that contain CTCs within the horizon. Rich, who really must finish reading Visser's _Lorentzian Wormholes_.
