Galactic settlement of low-mass stars as a resolution to the Fermi paradox (2210.10656v1)

Abstract: An expanding civilization could rapidly spread through the galaxy, so the absence of extraterrestrial settlement in the solar system implies that such expansionist civilizations do not exist. This argument, often referred to as the Fermi paradox, typically assumes that expansion would proceed uniformly through the galaxy, but not all stellar types may be equally useful for a long-lived civilization. We suggest that low-mass stars, and K-dwarf stars in particular, would be ideal migration locations for civilizations that originate in a G-dwarf system. We use a modified form of the Drake Equation to show that expansion across all low-mass stars could be accomplished in 2 Gyr, which includes waiting time between expansion waves to allow for a close approach of a suitable destination star. This would require interstellar travel capabilities of no more than ~0.3 ly to settle all M-dwarfs and ~2 ly to settle all K-dwarfs. Even more rapid expansion could occur within 2 Myr, with travel requirements of ~10 ly to settle all M-dwarfs and ~50 ly to settle all K-dwarfs. The search for technosignatures in exoplanetary systems can help to place constraints on the presence of such a "low-mass Galactic Club" in the galaxy today.

• The paper proposes that extraterrestrial civilizations may preferentially settle around long-lived low-mass stars (like K and M dwarfs), offering a potential resolution to the Fermi paradox.
• Using a modified Drake Equation including expansion, the model shows that even modest interstellar travel allows extensive settlement across the galaxy, prioritizing sustainable stellar environments.
• This hypothesis suggests future technosignature searches should focus on low-mass star systems, which could be home to a 'low-mass Galactic Club' of advanced civilizations.

Galactic Settlement of Low-Mass Stars as a Resolution to the Fermi Paradox

The paper by Haqq-Misra and Fauchez presents a novel perspective on the classic Fermi paradox by exploring the possibility that advanced extraterrestrial civilizations may be inclined to settle around low-mass stars, particularly K-dwarf stars. This hypothesis provides a potential resolution to the paradox by suggesting that while these civilizations expand through the galaxy, they choose not to settle systems like ours, originating from G-dwarf stars.

Core Hypothesis

The authors posit that the absence of extraterrestrial settlers in the solar system may be due to preferential expansion towards low-mass stars, K-dwarfs, and M-dwarfs, as these provide more sustainable environments for long-term habitation. This premise is grounded in the longevity of low-mass stars, which can significantly exceed the lifespan of G-dwarfs. Therefore, technological civilizations would logically aim to maximize their durability in the galaxy by prioritizing such stars for colonization.

Drake Equation with Expansion

To substantiate this hypothesis, the paper employs a modified form of the Drake Equation that includes a factor for expansion across stellar systems. The model takes into account the average navigable radius a civilization can cover, combined with interstellar travel capabilities. The authors demonstrate that settlements can occur extensively with modest interstellar travel, requiring less than a few light-years to reach adjacent stars. This suggests that even with current technological boundaries, a civilization can effectively spread across the galaxy within the purported 2 Gyr timeframe.

Implications for Galactic Expansion

The consideration of stellar movement and waiting times for close stellar passages presents a significant advancement over static expansion models. This dynamic allows for reduced travel distances and efficient spread across suitable stellar environments. In more rapid expansion scenarios—with timelines condensed to millions of years—a civilization could settle substantial portions of the galaxy if willing to undertake long-distance voyages.

Theoretical Postulates

Haqq-Misra and Fauchez highlight K-dwarf stars as particularly favorable destinations. These stars offer environments more closely aligned with those provided by G-dwarfs, yet escape the pitfalls of high energy output and short lifecycles. Their relatively stable spectral characteristics and the likelihood of sustaining planets within habitable zones make K-dwarfs attractive for civilizations originating from G-dwarf systems.

Future Prospects in Technosignature Searches

While the hypothesis proposed offers a viable explanation for the quietness of the cosmos, it also directs future search efforts towards low-mass stars. The search for technosignatures could be concentrated around K- and M-dwarf systems, which may be home to a "low-mass Galactic Club." Current observing capabilities, although limited in scope, provide initial weak constraints. However, with advancing telescopic technologies and refined detection methodologies, these searches may yield more definitive evidence of extraterrestrial technological activity.

Concluding Remarks

While the paper does not claim to conclusively resolve the Fermi paradox, it articulates a coherent argument that challenges the traditional assumptions about galactic settlement. It advocates for a nuanced approach to SETI, encouraging a focus on low-mass stellar populations and cautioning against assumptions based solely on observable phenomena within our solar system. This perspective reinvigorates discourse on extraterrestrial intelligence, emphasizing the necessity of continued exploration and theoretical modeling.