Related papers: Is there anybody out there?
Based on numbers of stars, supernova rates, and metallicity, a prior study (Dayal et al. 2015) concluded that large elliptical galaxies contain up to 10,000 times more habitable planets than the Milky Way and are thus the "cradles of life".…
The history of astronomical discovery shows that many of the most detectable phenomena, especially detection firsts, are not typical members of their broader class, but rather rare, extreme cases with disproportionately large observational…
In the 20th century the scientific search for extraterrestrial intelligence began, and the Drake equation was proposed to estimate the number of extraterrestrial species humanity could attempt to detect, N. This paper discusses the need to…
The Search for Extraterrestrial Intelligence (SETI) has heretofore been a largely passive exercise, reliant on the pursuit of technosignatures. Still, there are those that advocate a more active approach. Messaging Extraterrestrial…
The consequences are explored of an observationally established relation of the star formation rate (SFR) of star-forming galaxies with their stellar mass (M) and cosmic time (t), such that SFR is proportional to M x t^{-2.5}. It is shown,…
'Most habitable worlds in the cosmos will have no remotely detectable signs of life' is proposed as a biological hypothesis to be tested in studies of exoplanets. Habitable planets could be discovered elsewhere in the Universe, yet there…
This paper is concerned with a natural variant of the contact process modeling the spread of knowledge on the integer lattice. Each site is characterized by its knowledge, measured by a real number ranging from 0 = ignorant to 1 =…
As our ability to undertake more powerful Searches for Extraterrestrial Intelligence (SETI) grows, so does interest in the more controversial endeavour of Messaging Extraterrestrial Intelligence (METI). METI proponents point to the SETI…
We introduce an interacting particle system which models the inherited sterility method. Individuals evolve on $\mathbb{Z}^d$ according to a contact process with parameter $\lambda>0$. With probability $p \in [0,1]$ an offspring is fertile…
Upcoming next generation galactic surveys, such as GAIA and HERMES, will deliver unprecedented detail about the structure and make-up of our Galaxy, the Milky Way, and promise to radically improve our understanding of it. However, to…
The number N of detectable (i.e. communicating) extraterrestrial civilizations in the Milky Way galaxy is usually done by using the Drake equation. This equation was established in 1961 by Frank Drake and was the first step to quantifying…
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…
The last two decades have seen the number of known exoplanets increase from a small handful to nearly 2000 known exoplanets, thousands more planet candidates, and several upcoming missions that are expected to further increase the…
Current research indicates that (sub)surface ocean worlds essentially devoid of subaerial landmasses (e.g., continents) are common in the Milky Way, and that these worlds could host habitable conditions, thence raising the possibility that…
Each of the individual factors of the Drake Equation is considered. Each in turn is either abandoned or redefined and finally reduced to a single new factor, fd, the fraction of technological life that is detectable by any means. However,…
Von Hoerner (1975) examined the effects of human population growth and predicted agricultural, environmental, and other problems from observed growth rate trends. Using straightforward calculations, VH75 predicted the "doomsday" years for…
Galactic outflows are ubiquitous in galaxies containing active star formation or supermassive black hole activity. The presence of a large-scale outflow from the center of our own Galaxy was confirmed after the discovery of two large ($\sim…
Is life most likely to emerge at the present cosmic time near a star like the Sun? We consider the habitability of the Universe throughout cosmic history, and conservatively restrict our attention to the context of "life as we know it" and…
Provided significant future progress in artificial intelligence and computing, it may ultimately be possible to create multiple Artificial General Intelligences (AGIs), and possibly entire societies living within simulated environments. In…
Ambitious civilizations that expand for resources at an intergalactic scale could be observable from a cosmological distance, but how likely is one to be visible to us? The question comes down to estimating the appearance rate of such…