In visions of the future, colonists in the asteroid belt live in O'Neill cylinders.

In the future, there could be space cities in the asteroid belt. In visions, That cylinder-shaped space colony creates artificial gravitation using the centripetal force created by rotational motion. 

Wild visions are interesting. And one of the most interesting things is space cities called O'Neill cylinders. In that kind of cylinder-shaped space station rotating motion causes a centripetal force that creates artificial gravitation. That kind of solution makes it possible that humans can live in those space cities in the gravitational field. 

The artists' vision of the O'Neill cylinder and space city is humbler than the original visions of the O'Neill cylinders. There is a hollow core that rotates around its central axle. And that motion makes the artificial gravitation to the colony. 

When we think that the rotation speed of that kind of space colony must be very high that can create the same gravitation as Earth some people say that the motion will break the structure. The fact is that the gravitation must not be the same as it's on Earth. 

There are two possibilities where gravitation can use. 

1) Slowly rotating space station can make weak gravitation that can just anchor objects on the table. That is the more conventional way to make artificial gravitation than the fast-rotating space station. 

2) Fast rotating space station creates gravitation that is so strong as on Earth. The structures of that kind of space station must be very strong or there could be a magnetic system that pulls the core of that structure inside.

That magnetic structure keeps the space station in one piece even if the centripetal force is very strong. And without that magnetic pulling, they rip the space station to pieces. 

Image 2) NASA's vision of a large-scale O'Neill cylinder where plantations produce food for colonists. There are also forests that make the colony more comfortable. (Image: Wikipedia: O'Neill cylinder) 

Weak gravitation is better than without gravitation. And the purpose of gravitation can be just to anchor objects on the table. But if we think that the gravitation must be strong as on Earth. There is the possibility that in the middle of the cylinder is a magnet. That pulls its structure to the middle of it. The magnetic system will keep the structure as one piece. 

Well, somebody says that rotating motion makes people sick. That thing is not quite right. If there are no windows in that cylinder people would not see the rotation motion. There is also the possibility to use anti-nausea medicine on board that kinds of stations. 

When we think about the sickness that the rotation movement causes, we always forget that this station would be outside space. So people who would live on board that O'Neill cylinder is not living in regular houses. The selection process for those people would be very accurate. Those people are not moving to a regular house, and renting a flat. They are astronauts who are carefully selected. 

Those space people would move to space. The situation would be the same as we compare an astronaut who goes to the space station with a person who buys a bus ticket. The selection process of that astronaut is more accurate than a regular passenger in some city buses. 

https://scitechdaily.com/wild-research-project-reveals-how-future-cities-on-asteroids-could-work/

https://en.wikipedia.org/wiki/O%27Neill_cylinder