arXiv subjects

Colin R McInnes

Publications and source records attributed to Colin R McInnes.

2 recordsLinked to original sources

arXiv2026

Stellar engines and Dyson bubbles can be stable

A range of speculative space ventures envisage the use of ultra-large structures for the collection and reflection of light. Given the length-scale of such structures they cannot be considered as point masses for the calculation of gravitational and radiation pressure forces. Using a simplified model it will be demonstrated that ultra-large reflectors in static equilibrium levitating above a central star (so-called stellar engines) are always unstable if the reflector comprises a uniform disc. However, if the reflector has a non-uniform mass distribution, specifically a ring supporting a reflect or, a stellar engine can in principle be passively stable. Moreover, while it can be shown that static swarms of reflectors levitating above a central star (so-called Dyson bubbles) are unstable, in principle they can become passively self-stabilizing if arranged about the star as a dense cloud. While such ventures are clearly speculative, understanding the orbital dynamics of ultra-large structures, and in particular the conditions for passive stability, can provide insights into the properties of potential technosignatures in search for extraterrestrial intelligence studies.

astro-ph.SR↗

arXiv2025

Ringworlds and Dyson spheres can be stable

In his 1856 Adams Prize essay, James Clark Maxwell demonstrated that Saturn's rings cannot be comprised of a uniform rigid body. This is a consequence of the two-body gravitational interaction between a ring and planet resulting in instability. Similarly, it is also known that a so-called Dyson sphere encompassing a single star would be unstable due to Newton's shell theorem. A surprising finding is reported here that both a ring and a sphere (shell) can be stable in the restricted three-body problem. First, if two primary masses are considered in orbit about their common centre of mass, a large, uniform, infinitesimal ring enclosing the smaller of the masses can in principle be stable under certain conditions. Similarly, a Dyson sphere can, be stable, if the sphere encloses the smaller of the two primary masses, again under certain conditions. These findings extend Maxwell's results on the dynamics of rings and have an interesting bearing on so-called Ringworlds and Dyson spheres from fiction. Moreover, the existence of passively stable orbits for such large-scale structures may have implications for so-called techno-signatures in search for extra-terrestrial intelligence studies.

astro-ph.SR↗