Making Habitable Worlds: Planets Versus Megastructures

TL;DR

This work reevaluates the Dyson Sphere concept by highlighting its fundamental assumptions and the ecological risks of a megastructure around a star. It proposes an alternative ETI signature: relocating planets into the Habitable Zone with high-power laser propulsion, supported by analyses of Hohmann transfers and continuous-thrust models, including quantitative energy scales such as $P = \dfrac{M_p r c}{t^2}$ and $\dfrac{d^2 r}{dt^2} = \dfrac{P}{M_p c}$. The authors argue that detectable technosignatures could arise from such laser beaming, and they advocate focusing searches on planetary systems with Strange Exoplanetary Architectures (SEA) where engineered orbital configurations may be evident. The study also discusses the notion of 'service worlds' and underscores the practical and observational importance of considering SEA-rich systems for biosignature and technosignature detection. Overall, it broadens the scope of technosignature searches beyond traditional megastructures to dynamic planetary engineering plausible for advanced civilizations.

Abstract

In 2016, a star KIC 8462852 caught the world's attention due to a paper by citizen scientists who noticed its seemingly unexplainable brightness variations. The forward theory was offered - KIC 8462852 is surrounded by a Dyson sphere, a megastructure made by an alien civilization to collect all energy output from their star. Finally, in 2018, its light curve showed chromaticity more characteristic of the dust (from comets or asteroids) rather than of something made from solid material, but the world was woken up to the idea of megastructures. But, in Dyson's time, only Solar System planets were known; it took more than 20 years to realize that nature has no problem making planets and does it with a flair -- the total number of planets in the Galaxy is estimated to be in billions. With such abundance of planets, there would be no need to destroy the entire planetary system to make one sphere. Instead, a civilization can expand to a system that has planet(s) in the habitable zone (HZ), or a planet can be moved into it. Alternatively, a free-floating planet (FFP) can be captured and moved into the HZ. These shifts can be performed at a constant low-thrust acceleration using high power directional lasers, resulting in a gradual spiral transfer from one orbit to another. We propose here to search for ETI by looking for high-power laser technosignatures and consider merits of such signatures. We suggest to specifically pay attention to the multiple planetary systems that have Strange Exoplanetary Architectures (SEA) - unusual planetary arrangements that cannot be explained by current planetary formation theories, because these could be the result of ETI moving planets intentionally to suit their needs.

Figures (2)

• Figure 1: Hohmann transfer of Mars using lasers (the image is not to scale). The representation of a single large laser is merely illustrative; in practice, the configuration might involve multiple lasers operating from various orientations.
• Figure 2: Axes of Merit for high-power laser technosignature.