Infinite growth is absolutely possible as long as it’s combined with regular terrifying contraction and reduction; When growth slows down, engineer genocide until there’s plenty of room to grow. It’s a long embraced human tradition.

Get this if you put enough matter in one spot the mass of the matter acts as the piston compressing the material until it begins fusing enough to resist the inward pressure. This lasts as long as there are enough fuse-able materials in the mix, be aware they can get a little unstable when fuel gets low.

Stretchy kitties!