If Loud Aliens Explain Human Earliness, Quiet Aliens Are Also Rare

If life on Earth had to achieve n “hard steps“ to reach humanity's level, then the chance of this event rose as time to the nth power. Integrating this over habitable star formation and planet lifetime distributions predicts >99% of advanced life appears after today, unless n < 3 and max planet duration <50 Gyr. That is, we seem early. We offer this explanation: a deadline is set by loud aliens who are born according to a hard steps power law, expand at a common rate, change their volume appearances, and prevent advanced life like us from appearing in their volumes. Quiet aliens, in contrast, are much harder to see. We fit this three-parameter model of loud aliens to data: (1) birth power from the number of hard steps seen in Earth’s history, (2) birth constant by assuming a inform distribution over our rank among loud alien birth dates, and (3) expansion speed from our not seeing alien volumes in our sky. We estimate that loud alien civilizations now control 40%–50% of universe volume, each will later control ∼ 105–3 × 107 galaxies, and we could meet them in ∼200 Myr–2 Gyr. If loud aliens arise from quiet ones, a depressingly low transition chance (<∼10−4 ) is required to expect that even one other quiet alien civilization has ever been active in our galaxy. Which seems to be bad news for the Search for Extraterrestrial Intelligence. But perhaps alien volume appearances are subtle, and their expansion speed lower, in which case we predict many long circular arcs to find in our sky.

Interstellar Overdrive

‘Oumuamua was the first known interstellar object to visit the solar system. Avi Loeb’s Extraterrestrial attempts to make the case not only for ‘Oumuamua as a lightsail spacecraft created by extraterrestrial intelligence, but also for the notion of extraterrestrial intelligence itself.

Astrotheology’s contribution to public theology: From the extraterrestrial intelligence myth to astroethics

Public theology is conceived in the church, reflected on critically in the academy and addressed to the world for the sake of the world. The development of a theology of nature is included in the public theologian’s list of tasks of nature that is scripturally based and heavily informed by the natural sciences. Astrotheology is one product. Astrotheology engages astrobiology and other space sciences, firstly, by critically exposing the extraterrestrial intelligence (ETI) myth at the heart of science and secondly, by partnering in thinking through public policy proposals with astroethicists.Contribution: The HTS collection on ‘Theology and Nature’ sparks theological discussion both within and beyond the church. By developing the fields of astrotheology and astroethics, this article contributes to a ‘Theology of Nature’ as an exercise in Public Theology.

Intelligent Messages in Bacterial DNA – a Sequel to SETI?

It is proposed that the future trajectory of SETI (Search for Extraterrestrial Intelligence) and our exploration of alien planets and alien intelligence could be to consider the possibility of receiving and transmitting coded messages embedded as DNA inserts in bacteria and/or viruses. Physical space-travel and ambitions of space colonisation may well give way to a new era of “cultural” microbial colonisation of our galaxy.

Podcast: A Modern Way to Look for Aliens

The search for extraterrestrial intelligence is undergoing a 21st century transformation. The field is poised to lead the way as an example of interdisciplinary research and inclusive science.

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

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 (λA); (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.

From Interstellar Imperialism to Celestial Wayfinding: Prime Directives and Colonial Time-Knots in SETI

This article traces parallels between James Cook’s 1768 Endeavour voyage to measure the transit of Venus and current initiatives searching for extraterrestrial intelligence (SETI). While separated by vast time and space, both are united in their appeal to celestial frontier science in the service of all humanity, and contain discrepancies between their ethical protocols and probable outcomes. Past, present, and future colonial projects are interwoven by drawing on Dipesh Chakrabarty’s “time-knot,” Star Trek’s “prime directive,” and firsthand experience in SETI’s Indigenous studies working group. This analysis cautions against the current trend toward unabated interstellar imperialism and suggests alternative approaches for engaging outer spaces and beings through celestial wayfinding.