 Physical bodies are gone from 4-D, but theoretically can be re-manifest as they were.Stuff is Unity's manifestation in 4-D, appearing as an atomically undistinguishable mass that responds to intense thought and adapts itself to satisfy implicit need or desire.For example, Stuff appears as an instantaneous transfer FTL engine to a stranded inter-stellar ship, and transforms into a weapon needed by a scientist to defend himself against torture.