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Traditionally, secular evolution is defined as evolution of systems where the internal growth of structure and instabilities dominates the growth via external drivers (e.g. accretion/mergers). Most study has focused on 'isolated' galaxies,…
It is shown that space travel, even in the most distant future, will remain confined to our own planetary system, and a similar conclusion will hold forth for any other civilization, no matter how advanced it might be, unless those…
A key result of hydrogravitational dynamics cosmology relevant to astrobiology is the early formation of vast numbers of hot primordial-gas planets in million-solar-mass clumps as the dark matter of galaxies and the hosts of first life.…
This paper reviews selected aspects of the growth of cosmological structure, covering the following general areas: (1) expected characteristics of linear density perturbations according to various candidate theories for the origin of…
We present a model of the Galactic Habitable Zone (GHZ), described in terms of the spatial and temporal dimensions of the Galaxy that may favour the development of complex life. The Milky Way galaxy is modelled using a computational…
We investigate the effects of correlated global regulation mechanisms, especially Galactic gamma-ray bursts (GRBs), on the temporal distribution of hypothetical inhabited planets, using simple Monte Carlo numerical experiments. Starting…
We analyze the evolution of the potentially habitable planet Proxima Centauri b to identify environmental factors that affect its long-term habitability. We consider physical processes acting on size scales ranging from the galactic to the…
In this work, we aim to answer one crucial question behind the discrepancy between chemical trends of field stars and clusters in the Galactic disk: is the chemical gradient mismatch driven by cluster migration and differential…
The quest for life in the Universe is often affected by the free use of extrapolations of our phenomenological geocentric knowledge. We point out that the existence of a living organism, and a population of organisms, requires the existence…
(Shortened) We have used the measured properties of the stars in the 79 exoplanetary systems with one or more planets that have been observed in transit, to estimate each system's present habitability. The measured stellar properties have…
This article reviews the prevailing paradigm for how galaxies and larger structures formed in the universe: gravitational instability. Basic observational facts are summarized to motivate the standard cosmological framework underlying most…
Inflation has been the leading early universe scenario for two decades, and has become an accepted element of the successful `cosmic concordance' model. However, there are many puzzling features of the resulting theory. It requires both…
The breadth of topics that encompass the search for life has expanded and evolved significantly since the emergence of the field of astrobiology. Initial astrobiology centered investigations focused on detecting biosignatures in the Martian…
This paper investigates the possible use of space probes to explore the Milky Way, as a means both of finding life elsewhere in the Galaxy and as finding an answer to the Fermi paradox. I simulate exploration of the Galaxy by first…
The Solar System hosts the most studied and best understood major and minor planetary bodies - and the only extraterrestrial bodies to have been visited by spacecraft. The Solar System therefore provides important constraints on both the…
The habitable zones of main sequence stars have traditionally been defined as the range of orbits that intercept the appropriate amount of stellar flux to permit surface water on a planet. Terrestrial exoplanets discovered to orbit M stars…
This paper proposes a long term scheme for robotic exploration of the galaxy,and then considers the implications in terms of the `Fermi paradox' and our search for ETI. We discuss the parameter space of the `galactic ecology' of…
Astrophysical evidence suggests that the Sun was born near 5 kpc from the Galactic center, within the corotation radius of the Galactic bar, around 6-7 kpc. This presents challenges for outward migration due to the Jacobi energy constraint,…
We review how tides may impact the habitability of terrestrial-like planets. If such planets form around low-mass stars, then planets in the circumstellar habitable zone will be close enough to their host stars to experience strong tidal…
One of the most fundamental questions in exoplanetology is to determine whether a given planet is habitable. We estimate the relative likelihood of a planet's propensity towards habitability by considering key physical characteristics such…