Related papers: Is there anybody out there?
Bit strings rather than byte files can be a mode of transmission both for intelligent signals and for travels of extraterrestrial life. Kolmogorov complexity, i.e. the minimal length of a binary coded string completely defining a system,…
We motivate the \^G infrared search for extraterrestrial civilizations with large energy supplies. We discuss some philosophical difficulties of SETI, and how communication SETI circumvents them. We review "Dysonian SETI", the search for…
We introduce a mathematical framework for statistical exoplanet population and astrobiology studies that may help directing future observational efforts and experiments. The approach is based on a set of differential equations and provides…
Artificial broadcasts from extraterrestrial intelligences (ETIs) are a hypothetical class of celestial phenomena. Unlike known astrophysical objects, the societies that generate them may be able to replicate on galactic scales through…
Despite great advances in our understanding of the formation of the Solar System, the evolution of the Earth, and the chemical basis for life, we are not much closer than the ancient Greeks to an answer of whether life has arisen and…
Because cosmic rays are charged particles scrambled by magnetic fields, combining direct measurements with other observations is crucial to understanding their origin and propagation. As energetic particles traverse matter and…
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…
The preponderance of white dwarfs in the Milky Way were formed from the remnants of stars of the same or somewhat higher mass as the Sun, i.e., from G-stars. We know that life can exist around G-stars. Any technologically advanced…
We discuss how visions for the futures of humanity in space and SETI are intertwined, and are shaped by prior work in the fields and by science fiction. This appears in the language used in the fields, and in the sometimes implicit…
The Search for Extraterrestrial Intelligence (SETI) has thus far failed to provide a convincing detection of intelligent life. In the wake of this null signal, many "contact pessimistic" hypotheses have been formulated, the most famous of…
The Optical Search for Extraterrestrial Intelligence (OSETI) attempts to detect collimated, narrowband pulses of electromagnetic radiation. These pulses may either consist of signals intentionally directed at the Earth, or signals between…
We combine a semi-analytic model of galaxy evolution with constraints on circumstellar habitable zones and the distribution of terrestrial planets to probe the suitability of galaxies of different mass and type to host habitable planets,…
We estimate the relative likelihood of success in the searches for primitive versus intelligent life on other planets. Taking into account the larger search volume for detectable artificial electromagnetic signals, we conclude that both…
The Fermi Bubbles are giant Galactic structures observed in both gamma-rays and microwaves. Recent studies have found support for the hypothesis that the gamma-ray and microwave emission can both be understood as arising from a hard…
The search for extraterrestrial intelligence includes efforts to constrain populations of artificial broadcasts in other galaxies. Previous efforts use individualist methods, searching for single broadcasts with high signal-to-noise ratio.…
The observed value $\Lambda_{\rm obs}$ of the cosmological constant $\Lambda$ is extremely smaller than theoretical expectations, and the anthropic argument has been proposed as a solution to this problem because galaxies do not form when…
With no firm evidence for life beyond our solar system, inferences about the population observers such as ourselves rests upon the Earth as a single input, at least for now. Whilst the narrative of our home as a 'humdrum' system has become…
The notion of a Galactic Habitable Zone (GHZ), or regions of the Milky Way galaxy that preferentially maintain the conditions to sustain complex life, has recently gained attention due to the detection of numerous exoplanets and advances…
One of the major goals for astronomy in the next decades is the remote search for biosignatures (i.e.\ the spectroscopic evidence of biological activity) in exoplanets. Here, we adopt a Bayesian statistical framework to discuss the…
For centuries, humanity wondered if there were other worlds like ours in the Universe. For about a quarter of a century, we have known that planetary systems exist around other stars, and more than 3800 exoplanetary systems have been…