Related papers: Too Damned Quiet?
Vickers et al. (2025) established that 58.20% of astrobiology experts believe intelligent extraterrestrial life likely exists, providing the first empirical baseline for public comparison. We surveyed 6,114 highly educated and…
According to the "hard-steps" model, the origin of humanity required "successful passage through a number of intermediate steps" (so-called "hard" or "critical" steps) that were intrinsically improbable with respect to the total time…
In a previous paper we addressed the question "Does the Rapid Appearance of Life on Earth Suggest that Life is Common in the Universe?" The non-observability of recent biogenesis is a self-selection effect that needs to be considered if…
One of the beneficial outcomes of searching for life in the Universe is that it grants greater awareness of our own problems here on Earth. Lack of contact with alien beings to date might actually comprise a null "signal" pointing humankind…
A considerable fraction of multi-planet systems discovered by the observational surveys of extrasolar planets reside in mild proximity to first-order mean motion resonances. However, the relative remoteness of such systems from nominal…
Following on from ideas presented in a recent paper by Schneider et al. (2010) on "The Far Future of Exoplanet Direct Characterization", I argue that they have exaggerated the technical obstacles to performing such 'direct characterization'…
One primary reason for the formulation of the term Earth-like planet and the search for such planets in the galaxy is because life has arisen in such a world. Thus, this search seems justifiable as it is known here what one is looking for.…
No present observations suggest a technologically advanced extraterrestrial intelligence (ETI) has spread through the galaxy. However, under commonplace assumptions about galactic civilization formation and expansion, this absence of…
Our ability to explore the cosmos by direct contact has been limited to a small number of lunar and interplanetary missions. However, the NASA Starlight program points a path forward to send small, relativistic spacecraft far outside our…
For about the last 60 years the search for extraterrestrial intelligence has been monitoring the sky for evidence of remotely detectable technological life beyond Earth, with no positive results to date. While the lack of detection can be…
The observable universe is necessarily hospitable for life. There are indications, however, that the laws of physics and cosmological parameters need not take the form and values observed, and if they were slightly different life could not…
The results obtained in these experiments have revealed a remarkable resistance of extremophilic bacteria and archaea against different radiation sources (VUV, solar wind simulants, X rays) whenever protected by microsized carbonaceus…
We use a statistical model to investigate the detectability (defined by the requirement that they are in causal contact with us) of communicating civilizations within a volume of the universe surrounding our location. If the civilizations…
In the last few years, a number of planets have been proposed to orbit several post main-sequence binary star systems on the basis of observed variations in the timing of eclipses between the binary components. A common feature of these…
The detection of exoplanets orbiting other stars has revolutionized our view of the cosmos. First results suggest that it is teeming with a fascinating diversity of rocky planets, including those in the habitable zone. Even our closest…
If life is sustained by a process of photosynthesis, not necessarily the same existing on Earth, the surface temperature of the star and the orbit of the host planet cannot be whatsoever. In fact the global life cycle, no matter how…
Earth-like planets are expected to provide the greatest opportunity for the detection of life beyond the Solar System. However our planet cannot be considered a fair sample, especially if intelligent life exists elsewhere. Just as a…
This paper attempts to provide an estimation of the prevalence of hostile extraterrestrial civilizations through an extrapolation of the probability that we, as the human civilization, would attack or invade an inhabited exoplanet once we…
The probability that an exoplanet transits its host star is high for planets in close orbits, but drops off rapidly for increasing semimajor axes. This makes transit surveys for planets with large semimajor axes orbiting bright stars…
Sex is considered as an evolutionary paradox, since its evolutionary advantage does not necessarily overcome the two fold cost of sharing half of one's offspring's genome with another member of the population. Here we demonstrate that…