I was wondering what sort of advances it would take for making artificial gravity seem within reach for ships (not based on spin). I was thinking something along the lines of maybe using extremely pressureized gas. I realize the contribution from pessure is generally small compared to mass-energy, and so I assume a high enough pressure to start having noticeable gravity would be beyond the limits of our material technology to contain, but I don't know the specific numbers. Can someone well versed in the details of GR run some numbers for me on this to give me a feel for the scale of the problem? Thanks.