III. Ecosmos: A Revolutionary Fertile, Habitable, Solar-Bioplanet, Incubator Lifescape

I. Our EarthMost Distinction: A Rarest Planetary Confluence of Life in Person Favorable Conditions

Scharf, Caleb and Leroy Cronin. Quantifying the Origins of Life on a Planetary Scale. arXiv:1511.02549. The Columbia University astrobiologist and University of Glasgow biochemist scope out an advanced 2010s theoretical update of the 1960s Drake equation for better estimates of the likelihood of habitable abodes for organisms and peoples. See also A Probabilistic Framework for Quantifying Biological Complexity by Cronin, Stuart Marshall, and Alastair Murray at arXiv:1705.03460.

In this paper, we describe an equation to estimate the frequency of planetary “origin of life”-type events that is similar in intent to the Drake Equation but with some key advantages—specifically, our formulation makes an explicit connection between “global” rates for life arising and granular information about a planet. Our approach indicates scenarios where a shared chemical search space with more complex building blocks could be the critical difference between cosmic environments where life is potentially more or less abundant but, more importantly, points to constraints on the search. The possibility of chemical search-space amplification could be a major variance factor in planetary abiogenesis probabilities. (Significance)

Schwieterman, Edward, et al. A Limited Habitable Zone for Complex Life. arXiv:1902.04720. UC Riverside and NASA Astrobiology Institute scientists quantify another significant variable with regard to biospheric and atmospheric concentrations of carbon dioxide and carbon monoxide. While aerobic life from microbes to mammals requires a viable, stable CO2 range over time, CO levels are highly toxic for all organisms. Since numerous K and M-type dwarf stars are prone to CO, they are less habitable. Our G-type sun is a better place to be, if CO2 can be sustainably kept in a safe, conducive range.

The habitable zone (HZ) is defined as the range of distances from a host star within which liquid water may exist at a planet's surface. Substantially more CO2 than present in Earth's modern atmosphere is required to maintain clement temperatures. However, most complex aerobic life on Earth is precluded by CO2 levels of just a fraction of a bar. At the same time, most of the HZ volume resides in proximity to K and M dwarfs, which are more numerous than Sun-like G dwarfs but have greater abundances of atmospheric CO, a toxic gas for organisms. Here we show that the HZ for higher fauna is significantly limited relative to that for microbial life. These results cast new light on the likely distribution of complex life in the universe and the search for biosignatures and technosignatures. (Abstract excerpts)

Secco, Luigi, et al. Habitability of Local, Galactic and Cosmological Scales. arXiv:1912:01569. University of Padova astroscientists consider these near and far domains by way of the latest exoplanet and exosolar findings and again reach an auspicious conclusion. An “Earth peculiarity” appears due to features such as an optimum orbit around the sun, benign solar system, magnetic field strength, good nitrogen to oxygen ratio, ocean to land plate tectonics, an ideally placed large moon, obliquity tilt, and more. Akin to Planetary Astrobiology by Victoria Meadows, et al (2019, 2020 herein), as the second quotes alludes out of a concatenation of some 1020 candidate worlds, our emergent person/sapiensphere progeny could very well be its first, best, or last universal opportunity to observe, read, affirm self-select and begin a new creation.

The aim of this paper is to underline conditions necessary for the emergence and development of life. They are placed at a local planetary scale, a Galactic scale and within cosmic evolution. We will consider the circumstellar habitable zone (CHZ), a Galactic Habitable Zone (GHZ), and also a set of strong cosmological constraints to allow Anthropic life. Some requirements are specific to a single scale and their physical phenomena, while others are due to cumulative effects across scales. A surmise is that all the habitability conditions here so detailed must at least be met. Thus, some sixty years later a human-like presence may appear as "a monstrous sequence of accidents" as (Fred) Hoyle (1959) thought, or as a providential collaboration which can imply how finely tuned is the architecture within which precious Life is embedded. (Abstract edits)

Starting from the local scale, life leads to connect us with the largest scale, that of Universe. From this analysis a possible scenario arises in which links among the different scales are advanced. Even if possibly partial, a large set of minimum conditions has been identified which must be met for allowing life. The consequence of these conditions is that if we look at life from the probability point of view and then regard it as a complex phenomenon composed, by compatible and independent events, the probability to get it tends drastically to zero. But here we are! (24)

Seppeur, Sonja. Impact of Gas Giant Instabilities on Habitable Planets. arXiv:1802.05736. A Goethe University, Frankfurt, astrophysicist posts an extensive study to date of the better or worse effect that gaseous worlds can have by their common presence and temporal movements upon solar system habitability zones. In regard, as Alessandro Morbidelli (search) and colleagues have found, our own hot Jupiter has been quite conducive by moving inward and then back so as to clear out the usual crunch of close-in rocky planets. The outward served a well-spaced orbit for Earth. One more feature amongst the cosmic contingencies is added to an especial significance for this home bioworld.

The detection of many extrasolar gas giants with high eccentricities indicates that dynamical instabilities in planetary systems are common. These instabilities can alter the orbits of gas giants as well as the orbits of terrestrial planets and therefore eject or move a habitable planet out of the habitable zone. In this work 423 simulations with 153 different hypothetical planetary systems with gas giants and terrestrial planets have been modelled to explore the orbital stability of habitable planets. Planetary systems consisting of two giant planets are fairly benign to terrestrial planets, whereas six giant planets very often lead to a complete clearing of the habitable zone. Observed gas giants with eccentricities higher than 0.4 and inclinations higher than 20 degrees have experienced strong planet-planet scatterings and are unlikely to have a habitable planet in its system. (Abstract excerpts)

Simpson, Fergus. An Anthropic Prediction for the Prevalence of Waterworlds. arXiv:1607.03095. As myriad orbital objects of every possible kind are being detected, the University of Barcelona, Institute for Cosmic Sciences, researcher notes that in contrast to a default state of wholly wet or dry surfaces, Earth’s mottled mantle of ocean and land is a rare anomaly. By way of a “planetary fecundity,” life has been able to evolve from primitive rudiments to human observers, thus an anthropic explanation. We include longish quotes to catch the gist, which appends another reason why this home Earth is so uniquely precious.

Should we expect most habitable planets to share the Earth's marbled appearance? Terrestrial planets within the habitable zone are thought to display a broad range of water compositions, due to the stochastic nature of water delivery. Such diversity, taken at face value, implies that the surfaces of most habitable planets will be heavily dominated by either water or land. Convergence towards the Earth's equitably partitioned surface may occur if a strong feedback mechanism acts to regulate the exposure of land. It is therefore feasible that the Earth's relatively balanced division of land and sea is highly atypical amongst habitable planets. We construct a simple model for the anthropic selection bias that may arise from an ensemble of surface conditions. Across a broad class of models we consistently find that (a) the Earth's ocean coverage of 71% can be readily accounted for by observational selection effects, and (b) due to our proximity to the waterworld limit, the maximum likelihood model is one where the majority of habitable planets are waterworlds. This 'Dry Earth' scenario is consistent with results from numerical simulations, and could help explain the apparently low-mass transition in the mass-radius relation. (Abstract)

On a purely statistical basis, one naıvely expects to find a highly asymmetric division of land and ocean surface areas. A natural explanation for the Earth’s equitably partitioned surface is an anthropic selection process. We have highlighted two mechanisms which could be responsible for driving this selection effect. First of all, planets with highly asymmetric surfaces (desert worlds or waterworlds) are likely to produce intelligent species at a much lower frequency. Secondly, planets with larger habitable areas are capable of sustaining larger populations. Both of these factors imply that our host planet has a greater habitable area than most life-bearing worlds. (7) It has been argued that the apparently unique and special properties of the Earth is indicative of the sparsity of life in the Universe - the so-called ‘Rare Earth hypothesis’. However this interpretation fails to account for one of the factors which controls the fecundity: the number of observers produced by each planet. This amplifies the already considerable observational selection effects associated with the emergence of life. The parameters of an observer’s host planet are heavily skewed in favour of those conditions which maximize the abundance of life, not just the probability of its emergence. The apparent fine-tuning of the Earth’s parameters need not reflect the sparsity of life in the cosmos, but on the contrary, it may be driven precisely because we are a small piece within a vast ensemble. (8)

Simpson, Fergus. The Longevity of Habitable Planets and the Development of Intelligent Life. International Journal of Astrobiology. 16/3, 2017. The University of Barcelona cosmologist applies mathematical finesse to figure how much duration is actually necessary for life to evolve and emerge from microbes of a collaborative sapience able to do this. As a result, another vital condition is added of an extended length of time it seems to require, some billion years in our Earthly case.

Why did the emergence of our species require a timescale similar to the entire habitable period of our planet? Our late appearance has previously been interpreted by Carter (2008) as evidence that observers typically require a very long development time, implying that intelligent life is a rare occurrence. Here we present an alternative explanation, which simply asserts that many planets possess brief periods of habitability. We also propose that the rate-limiting step for the formation of observers is the enlargement of species from an initially microbial state. In this scenario the development of intelligent life is a slow but almost inevitable process, greatly enhancing the prospects of future SETI experiments such as the Breakthrough Listen project. (Abstract)

The formation of the Earth did not require billions of years because it was an improbable event - many other planets formed on a similar timescale - it required billions of years because it involved fundamentally slow processes. These include the collapse of cosmic structure, the life span of the first stars, and the growth of planetesimals. Similarly, the development time for mankind may have been limited by a slow process rather than a difficult one. (268)

Slijepcevic, Predrag and Chandra Wickramasinghe. Reconfiguring SETI in the Microbial Context: Panspermia as a Solution to Fermi's Paradox. Biosystems. August, 2021. As our conceptions of what constitutes intelligence and the modes from which it can appear expand in scope, veteran Brunel University and University of Buckingham, UK life and mind investigators (search each) consider ways that a newly fertile cosmos which fills itself with micro-organisms can also possess a relative modicum of comprehension.

All SETI (Search for Extraterrestrial Intelligence) programmes that were conceived and put into practice since the 1960s have been based on anthropocentric ideas concerning the definition of intelligence on a cosmic-wide scale. Brain-based neuronal intelligence, augmented by AI, are currently thought of as being the only form of intelligence that can engage in SETI-type interactions, and this assumption is likely to be connected with the dilemma of the famous Fermi paradox. We argue that high levels of intelligence and cognition inherent in ensembles of bacteria are much more likely to be the dominant form of cosmic intelligence, and the transfer of such intelligence is enabled by the processes of panspermia. We outline the main principles of bacterial intelligence, and how this intelligence may be used by the planetary-scale bacterial system, or the bacteriosphere, through processes of biological tropism, to connect to any extra-terrestrial microbial forms, independently of human interference. (Abstract)

Smith, Howard. Alone in the Universe. Zygon: Journal of Religion and Science. 51/2, 2016. In an Exoplanets and Astrotheology section, the Harvard-Smithsonian Center for Astrophysics scientist and philosopher updates his conclusion, as broached in American Scientist for July-August 2011, that based on a 2010s multitude of cosmological findings we human beings are most likely the only sapient personage. As this section along with Astrobiology, ExoEarths and elsewhere reports, such an epochal realization is in fact dawning upon us. A May 2016 Scientific American article Born of Chaos (Batygin), for example, describes our own solar systems as a uniquely ordered anomaly well suited for a long term habitable Earth. And from a Jewish perspective, the author notes that in his 2006 book Let There Be Light he evoked John A. Wheeler to say that we peoples might be the universe’s way of self-observation so as to bring into full creation.

We are probably alone in the universe—a conclusion based on observations of over 4,000 exoplanets and fundamental physical constraints. This article updates earlier arguments with the latest astrophysical results. Since the discovery of exoplanets, theologians have asked with renewed urgency what the presence of extraterrestrial intelligence (ETI) says about salvation and human purpose, but this is the wrong question. The more urgent question is what their absence says. The “Misanthropic Principle” is the observation that, in a universe fine-tuned for life (“Anthropic Principle”), the circumstances necessary for intelligence are rare. Rabbis for 2,000 years discussed the existence of ETI using scriptural passages. We examine the traditional Jewish approaches to ETI, including insights on how ETI affects our perception of God, self, free-will, and responsibility. We explore the implications of our probable solitude, and offer a Jewish response to the ethical lessons to be drawn from the absence of ETI. (Abstract)

Smith, Howard A.. The End of Copernican Mediocrity: How Modern Astrophysics Has Reinvigorated the Spiritual Dimension. Zoe Imfeld and Andreas Losch, eds.. Our Common Cosmos. London: Bloomsbury, 2018. The Harvard Smithsonian astronomer and author (search) claims that the long “misanthropic” removal of Earth and human beings from any central place, lately into a multiverse, has been way overdone. In the later 2010s, two features can help us recover a new identity and significance. The first, familiar reason is atomic and cosmic parameters which are precisely set for life and people, aka the Anthropic principle. A second factor, to which the author has contributed, is that our home planet where intelligent observers can evolve seems to be a rarest cocatenation of favorable galactic, solar, geologic, chemical, and atmospheric conditions, as our Earthropic section documents. A vital 21st century Copernican revolution could then be in our very midst, akin to this sourcesite, if we might only be of a mind to ask and see.

Even if the formation of life were inevitable on every planet in the universe with liquid water, and even if the Milky Way galaxy has millions of water=bearing Earth-sized planets, my conclusion is that for all practical purposes we and our descendants for at least 100 generations are living in solitude. We are most probably alone. To recognize this state is to have a renewed appreciation for our good future and to acknowledge that life on Earth is precious and deserves supreme respect. Humanity is not mediocre. (9)

But conscious life appears to be a remarkable achievement of the universe – not an attribute one would have predicted for an ensemble of atoms. Even if we are not unique we should admit that the bias underlying the modern preference for mediocrity – that we are nothing more than a random accident – may no longer be viable. The Anthropic Principle intimates that some feature of nature endowed the cosmos with this capacity from the big bang and over eons of evolution. If so, we are representatives of that teleological end point, and serve a cosmic purpose of extraordinary significance. (17-18)

Spalding, Christopher, et al. The Resilience of Kepler Systems to Stellar Obliquity. arXiv:1803.01182. Cal Tech planetary scientists CS, Noah Marx and Konstantin Batygin add still another highly variable feature of solar systems whence an axial tilt of its sunny star has a controlling impact on the number, orbital paths, and stability of any entrained worlds.

The Kepler mission and its successor K2 have brought forth a cascade of transiting planets. Many of these planetary systems exhibit multiple members, but a large fraction possess only a single transiting example. This overabundance of singles has lead to the suggestion that up to half of Kepler systems might possess significant mutual inclinations between orbits, reducing the transiting number. Here, we investigate the ubiquity of the stellar obliquity-driven instability within systems with a range of multiplicities. We find that most planetary systems analysed, including those possessing only 2 planets, underwent instability for stellar spin periods below ~3 days and stellar tilts of order 30 degrees. (Abstract excerpts)

Spohn, Tilman. Special Issue: Planetary Evolution and Life. Planetary and Space Science. 98/1, 2014. An introduction to this edition with six co-editors including Helmut Lammer and Frances Westall as we Earthlings began our near and far cosmic census of habitable ecobiospheres. With this home world as a measure, the 21st century project going forward involves quantifying an array of features such as core composition, geochemistry, outgasings, atmospheres, mantle hydration, and much more. See for example herein Plate Tectonics on Rocky Exoplanets, Earth-Like Habitats in Planetary Systems, and Biotic vs. Abiotic Earth. But an inkling seems to carry through the papers that this precious animate orb looks increasingly special and maybe unique.

Stern, Robert and Taras Gerya. The importance of continents, oceans and plate tectonics for the evolution of complex life: implications for finding e. Nature Scientific Reports. 14/8552, 2024. A UT Dallas Earth system scientist and an ETU Zurich geochemist make a latest strong case that our past billion years of drifting surface forms with a general land/sea ratio of 30/70 ratio is especially conducive for a life’s developmental emergence and also seems to be a rarest habitable planet occasion.

Within astronomical and biological parameters, the Drake Equation predicts that there should be many exoplanets in our galaxy with active communicative civilizations (ACCs). This optimism, however, is not supported by evidence, often referred to as the Fermi Paradox. Here, we elaborate on the importance of planetary tectonics for biological evolution by adding two additional terms to the Drake Equation: foc (the fraction of habitable exoplanets with continents and oceans) and fpt (the fraction of habitable exoplanets with continents and oceans that have had plate tectonics operating for at least 0.5 Ga). We propose that an absence of ACCs reflects the scarcity of continents and oceans on exoplanets with primitive life. (Excerpt)

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