English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

I apply the thermodynamics of radiation to Dyson spheres as machines that dowork or computation, and examine their observational consequences. I identifyfour properties of Dyson spheres that complicate typical analyses: globally,they may do no work in the usual sense; they use radiation as the source andsink of energy; they accept radiation from a limited range of solid angle; andthey conserve energy flux globally. I consider three kinds of activities:computation at the Landauer limit; dissipative activities, in which the energyof a sphere's activities cascades into waste heat, as for a biosphere; and"traditional" work that leaves the sphere, such as radio emission. I apply theLandsberg formalism to derive efficiency limits in all 3 cases, and show thatoptical circulators provide an "existence proof" that greatly simplifies theproblem and allows the Landsberg limit to be plausibly approached. I find thatfor computation and traditional work, there is little to no advantage tonesting shells (as in a "Matrioshka Brain"); that the optimal use of mass isgenerally to make very small and hot Dyson spheres; that for "complete" Dysonspheres we expect optical depths of several; and that in all cases theLandsberg limit corresponds to a form of the Carnot limit. I explore how theseconclusions might change in the face of complications such as the sphere havingpractical efficiencies below the Landsberg limit (using the endoreversiblelimit as an example); no use of optical circulators; and swarms of materialsinstead of shells.

Application of the Thermodynamics of Radiation to Dyson Spheres as Work Extractors and Computational Engines, and their Observational Consequences