Orion’s Arm is a game for physicists and like minded people that my son Josh mentioned to me. Apparently the game can be won if you can design a Dyson Sphere that could be built with known technologies and theoretically possible materials. My preliminary proposal to solve this problem is called a “Sellnow Cylinder” Megastructure and it may have several variations depending on how the mathematics works out.
What is a Sellnow Cylinder Megastructure? Josh mentioned that Isaac Arthur (A futurist on youtube) has come up with a way to dynamically keep a Ringworld type structure from destroying itself. Larry Niven developed the Ringworld concept in several science fiction books. Given a functional design for a Ringworld it should be possible to upscale a Ringworld design and make a Sellnow Cylinder. A Sellnow Cylinder is a space based megastructure with dynamic controls that encloses an entire star with a Cylinder providing living space for humans on parts of the inside similar to a Dyson Sphere or Ringworld.
A Sellnow Cylinder is simply a large ringworld using dynamic controls with the ends of the cylinder capped off. The internal volume of the cylinder would not have to be entirely empty but could be filled in part to provide physical stability or for other purposes. Continuous circular ridges could be made similar to mountain ranges to increase livable surface area and to hold air/water in place. Exotic future materials with extraordinary physical properties would make this more feasible but it may be possible to make the Cylinder with known materials provided some type of dynamic controls are applied to stop it from flying apart or crashing into the star while rotating around a moving galaxy orbiting star. This concept could provide equal livable surface area to a hypothetical Dyson Sphere design which is desirable in the Orion’s Arm discussions as described to me.
I am a retired Electrical Engineer with cancer and it has been a long time since I have taken an advanced mathematics course in college. A rigorous mathematical investigation of a conceptual Sellnow Cylinder is beyond my capabilities at this point in my life. If any qualified person is interested in working out the math for this conceptual idea please contact me and I will give you joint credit with me for this idea.