why outer space?

Al Globus wrote:

> Unfortunately, I think rotating cylinders want to precess until they
> rotate end-over-end (assuming equal mass distribution, any real
> physicist out there, please check).

I'm not a Real Physicist (TM) but I do have a degree in physics.

I'm pretty sure that pairs of habitats don't have this problem,
the system has no angular momentum so there's no way its
going to gain any without an external force.

> Stability is important, so I think we'd better stick with Tori.

Tori can wobble too, according to a CD I just tossed in the air ;-)

Actually probably all axially symmetric masses can wobble at a multiple of
the rotation rate (I think for small wobbles its exactly a factor
of two forget which way.)

Still, the advantage of a Torus is that the wobble doesn't get worse
over time. With a single cylinder it will. Double tori can't wobble
either. Moving mass from one to the other will mess things up, but
that can be compensated for by keeping the angular momentum
constant (moving heavy counterweight masses out and in.)