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Surprisingly, Some Dyson Spheres and Ringworlds Can Be Stable
Slashdot reader Required Snark shared this article from Phys.org: In the realm of science fiction, [sun-energy capturing] Dyson spheres and ringworlds have been staples for decades. But it is well known that the simplest designs are unstable against gravitational forces and would thus be torn apart. Now a scientist from Scotland, UK has shown that certain configurations of these objects near a two-mass system can be stable against such fractures... [A] rigid ring around a star or planet, as in Larry Niven's "Ringworld" series of novels, is also unstable, as it would drift under any slight gravitational differences and collide with the star. So [engineering science professor Colin] McInnes considered a restricted three-body problem where two equal masses orbit each other circularly with a uniform ring of infinitesimal mass rotating in their orbital plane. The ring could enclose both masses, just one or none... McInnes also investigated a shell-restricted three-body problem with the shell also of infinitesimal mass, again with the shell enclosing two masses, one or none. For the restricted ring, McInnes found that there are seven equilibrium points in the orbital plane of the dual masses, on which, if the ring's center were placed, it would stay and not experience stresses, akin to the three stable Lagrange points where a small mass can reside permanently for the two-body problem... McInnes restricted this research to a planar ring (in the plane of the circularly orbiting masses) but says it can be shown that a vertical ring, normal to the plane, can also generate equilibria... These results can aid the search for extraterrestrial intelligence, McInnes said, "If we can understand when such structures can be stable, then this could potentially help direct future SETI surveys." An important technosignature would be one bright star orbiting in tandem with an object showing a strong infrared excess. Shells around a sun-exoplanet pair or an exoplanet-exoplanet pair could also be possible. A nested set of Dyson spheres is also a feasible geometry. In 2003 Ringworld author Larry Niven answered questions from Slashdot readers... Read more of this story at Slashdot.
Slashdot reader Required Snark shared this article from Phys.org:
In the realm of science fiction, [sun-energy capturing] Dyson spheres and ringworlds have been staples for decades. But it is well known that the simplest designs are unstable against gravitational forces and would thus be torn apart. Now a scientist from Scotland, UK has shown that certain configurations of these objects near a two-mass system can be stable against such fractures...
[A] rigid ring around a star or planet, as in Larry Niven's "Ringworld" series of novels, is also unstable, as it would drift under any slight gravitational differences and collide with the star. So [engineering science professor Colin] McInnes considered a restricted three-body problem where two equal masses orbit each other circularly with a uniform ring of infinitesimal mass rotating in their orbital plane. The ring could enclose both masses, just one or none... McInnes also investigated a shell-restricted three-body problem with the shell also of infinitesimal mass, again with the shell enclosing two masses, one or none.
For the restricted ring, McInnes found that there are seven equilibrium points in the orbital plane of the dual masses, on which, if the ring's center were placed, it would stay and not experience stresses, akin to the three stable Lagrange points where a small mass can reside permanently for the two-body problem... McInnes restricted this research to a planar ring (in the plane of the circularly orbiting masses) but says it can be shown that a vertical ring, normal to the plane, can also generate equilibria...
These results can aid the search for extraterrestrial intelligence, McInnes said, "If we can understand when such structures can be stable, then this could potentially help direct future SETI surveys." An important technosignature would be one bright star orbiting in tandem with an object showing a strong infrared excess. Shells around a sun-exoplanet pair or an exoplanet-exoplanet pair could also be possible. A nested set of Dyson spheres is also a feasible geometry.
In 2003 Ringworld author Larry Niven answered questions from Slashdot readers...
Read more of this story at Slashdot.
