Subspace

Subspace is the idea of “space between space”. When a spacecraft is at warp, it is contained within an isolated bubble of spacetime that fits “in-between” the rest of spacetime, without exhibiting any apparent external geometry or effects. This region is referred to as subspace. Warp drives that enter subspace cannot communicate or interact with the rest of the universe via any normal means, but they do exert ripples throughout spacetime that propagate much faster than the speed of light, which are detectable both within and outside of subspace.

Any matter that “enters” subspace - i.e. anything that is pushed outside of an active warp bubble - is lost to oblivion.