I'm writing a sci-fi story and I'd like to make it, at the very least, scientifically plausible (in the way that alcubirre warp drives are possible assuming we could get our hands on something with negative mass which, as far as we know, doesn't exist). The basic assumption for these questions is that we have the ability to curve spacetime to arbitrary specifications at will. Presumably this is done using a machine of some kind which may or may not be turned on and off, but the how isn't important to my story since it's "cleverly" hidden behind a spacer guild/cult (the real reason is that I don't give a crap and want the reader to just accept that its possible). The setup is this: a space ship (which, for the sake of simplicity, is a sphere) has a double external hull and a double internal hull. For simplicity assume spacetime outside is perfectly flat. Between the two outer hulls spacetime is curved so that between the inner and outer hulls the slope of spacetime is linear (rather than actually curved) and roughly equivalent to that on the surface of Earth. Between the two inner hulls spacetime is again curved such that it is again flat on the inside of the inner sphere. If I understand the idea of curved spacetime this would mean that, for someone between the inner and outer hulls they'd feel a gravitational force towards the inner hulls, while those outside outer hulls or inside the inner would be in freefall (if this interpretation is wrong please me know as my questions are all based on this). Now the questions. As I understand it if the transition from flat to angled spacetime was discontinuous (pointy) it would act like a domain wall. If this is correct what would be the result of crossing it by way of a ladder? (I imagine something really bad involving some immense tidal forces) Given that that's probably a bad idea what would the effect of passing through the transition if we made the gradient 1 cm in width? 1m? How wide would it have to be to make traversing the interface survivable? Comfortable? What would be the effect of something which lay permanently across the interface (such as power cables or support pylons keeping the hulls separated)? If the gradient were caused by a machine located at the very centre which could be turned on and off (instead of something intrinsic to the double-walled hulls which permanently bent spacetime), what would be the effect to people and objects within fields of shutting it off immediately? Presumably spacetime would rebound to its flat equilibrium state, but how fast would this be? Would it oscillate or just return immediately to flat? If it was reduced slowly what would the effects be? I would rather do this with an absolute bare minimum of equations, but if they're necessary I won't shy away from them (assuming I can understand them well enough to explain what they're doing).