[Arthur Wildfire! March]

I'm no rocket scientist, so this is just a low-informed stab at the issue. Dense mass seems to me to be the expensive way to solve the problem. We've all seen artificial gravity from spinning. Motion is the cheaper solution, IMHO. You could combine the two, but in the end, it should depend more on motion and less on mass. Enough energy for that motion is practically free in space, with unfiltered sunlight for solar collecters.

[Poincare]

You are correct. We have the ability to simulate gravity's effect by using spinning at reasonable cost. As of yet we have no suitable "dense matter" that we could use and the techiques of handling and using it would be engineering problems indeed.

It is those problems that I find most interesting. The suggestion of dense matter raises the opportunity for thought experiments--the most fun part of physics, IMHO. Back-of-envelope calcs show that a piece of "dense matter" at a distance of 5 meters would need to be (about) 1/2,000,000,000,000 the mass of the Earth to effect 1 g. Getting closer than say 3 meters would be very dangerous.