Isn't size and speed the issue? For a 50m radius don't you need about 10 RPM (rotation once every 6 seconds!)? That's actually right at the maximum dimension

Isn't size and speed the issue? For a 50m radius don't you need about 10 RPM (rotation once every 6 seconds!)? That's actually right at the maximum dimension of the ISS, no? And you're going to feel the gravity differential if you aren't exactly on the rim. We'd have to get significantly better at building much bigger space structures before rotating them will be even remotely feasible.