A Statistical Estimation of the Occurrence of Extraterrestrial Intelligence in the Milky Way Galaxy (2012.07902v2)

Abstract: In the field of Astrobiology, the precise location, prevalence and age of potential extraterrestrial intelligence (ETI) have not been explicitly explored. Here, we address these inquiries using an empirical galactic simulation model to analyze the spatial-temporal variations and the prevalence of potential ETI within the Galaxy. This model estimates the occurrence of ETI, providing guidance on where to look for intelligent life in the Search for ETI (SETI) with a set of criteria, including well-established astrophysical properties of the Milky Way. Further, typically overlooked factors such as the process of abiogenesis, different evolutionary timescales and potential self-annihilation are incorporated to explore the growth propensity of ETI. We examine three major parameters: 1) the likelihood rate of abiogenesis ({\lambda}A); 2) evolutionary timescales (Tevo); and 3) probability of self-annihilation of complex life (Pann). We found Pann to be the most influential parameter determining the quantity and age of galactic intelligent life. Our model simulation also identified a peak location for ETI at an annular region approximately 4 kpc from the Galactic center around 8 billion years (Gyrs), with complex life decreasing temporally and spatially from the peak point, asserting a high likelihood of intelligent life in the galactic inner disk. The simulated age distributions also suggest that most of the intelligent life in our galaxy are young, thus making observation or detection difficult.

• The paper uses a sophisticated Monte Carlo galactic simulation model incorporating astrophysical and biological parameters to estimate the spatial-temporal variation of extraterrestrial intelligence (ETI) in the Milky Way.
• Simulation results indicate that the peak occurrence of ETI is likely in an annular region about 4 kpc from the Galactic Center around 8 billion years ago.
• The probability of self-annihilation is identified as a critical determinant for ETI prevalence, suggesting the Galactic inner disk as a key target for SETI and offering a possible explanation for the Fermi Paradox.

Statistical Estimation of the Occurrence of Extraterrestrial Intelligence in the Milky Way

The investigation of extraterrestrial intelligence (ETI) within our own galaxy presents a daunting challenge due to inherent uncertainties and the complex interplay of variables influencing the emergence and survival of intelligent life. This paper attempts to extrapolate the spatial-temporal variation of ETI across the Milky Way using a sophisticated galactic simulation model. Combining astrophysical and biological considerations, the authors provide a comprehensive framework to address traditionally unexplored parameters concerning ETI.

Methodological Approach

The authors adopt a Monte Carlo simulation approach, employing a Lagrangian model enriched with extensive astrophysical data to simulate conditions favorable for the emergence of intelligent life in the galaxy. The model integrates various factors: the process of abiogenesis, evolutionary timelines, and the probability of self-annihilation of life. Its foundation lies in simulating Sun-like stars with Earth-like planets capable of harboring life, taking into account the initial mass function and chemical evolution.

Key parameters analyzed include:

• Abiogenesis likelihood (λA): Modeled as a Poisson process, simulating the emergence of life under Earth-like conditions.
• Self-annihilation probability (Pann): Acknowledging the potential self-destruction scenarios for intelligent civilizations, thus impacting their prevalence.
• Evolutionary timescales (Tevo): Considering variability in the time required for life to evolve into intelligence on Earth-like planets.

Results and Implications

The simulation results underscore that the spatial-temporal distributions of ETI peak in an annular region approximately 4 kpc from the Galactic Center around 8 billion years ago. Furthermore, the probability of ETI self-annihilation emerged as a critical determinant for the prevalence of intelligent life.

The implications of these findings are profound for the Search for Extraterrestrial Intelligence (SETI):

• Practical Considerations: The Galactic inner disk, especially approximately 4 kpc from the center, should be a focal point for SETI efforts, as it may harbor the maximum potential for intelligent life.
• Theoretical Speculation: The possibility of widespread self-annihilation suggests a potential explanation for the Fermi Paradox, where the expected ubiquity of intelligent life remains undetected. While the abiogenesis rate appears not to significantly influence the prevalence of ETI within the tested range, self-annihilation presents a plausible filter impacting the evolutionary trajectory of intelligent civilizations.

Future Outlook

This research provides a blueprint for future astrobiological studies, highlighting the importance of incorporating probabilistic models to gauge the existence of complex life forms. The authors acknowledge the limitations inherent in their model, particularly the coarse nature of galactic simulations lacking stellar kinematics considerations. Nonetheless, the paper suggests an optimistic outlook for the abundance of young ETI that may yet evolve into detectable civilizations.

Further advancements in astronomical observations and model refinement will likely enrich our understanding of complex life within the galaxy, progressively illuminating the pathway forward for detecting ETI. The dynamic interplay of critical parameters such as self-annihilation presents intriguing prospects for clarifying the conditions conducive to sustainable intelligent life in the cosmos.