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  • richardmitnick 12:39 pm on June 23, 2018 Permalink | Reply
    Tags: "Stop looking for ET: modelling suggests we’re alone in the universe", , , Fermi Paradox, Future of Humanity Institute,   

    From Future of Humanity Institute at University of Oxford via COSMOS: “Stop looking for ET: modelling suggests we’re alone in the universe” 

    U Oxford bloc

    From University of Oxford

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    Future of Humanity Institute

    COSMOS

    20 June 2018
    Andrew Masterson

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    Contact, Jodi Foster. No image credit found

    Despite the small matter of lack of evidence, most astrophysicists and cosmologists today are persuaded that extra-terrestrial intelligent life must exist.

    The logic behind the assumption seems compelling. There are billions of galaxies in the universe, each containing billions of stars, around a proportion of which orbit billions of planets. Given the vastness of those numbers, it would be statistically perverse to suggest that intelligent life evolved only once in the entire system.

    But what, however, if the startlingly improbable is nevertheless the truth? What if Homo sapiens is, in fact, the only species ever in the entire history of the universe to invent radio, build an X-ray observatory, and send a ship into space?

    What if – the existence of exoplanets coated in blue-green slime notwithstanding – we are utterly on our own?

    That’s the contention of physicists Anders Sandberg, Eric Drexler and Toby Ord, all of the Future of Humanity Institute at Oxford University in the UK. In a paper lodged on the pre-print server Arxiv, and thus still awaiting peer review, the trio model what happens when two touchstones of astrobiology – the Fermi Paradox and the Drake Equation – are combined and subjected to mathematical rigour.

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    The Fermi Paradox, named for Dr. Enrico Fermi, describes the apparent contradiction between the lack of evidence of extraterrestrial civilizations and the high probability that such alien life exists. AP

    Frank Drake, SET Institute. No image credit

    Drake Equation, Frank Drake, Seti Institute

    The results, it must be said, aren’t good, at least for people hopeful that somewhere, out there, at least one alien civilisation is bubbling along.

    Existing calculations for the probability of extra-terrestrial intelligent life, they report, rest on uncertainties and assumptions that lead to outcomes containing margins for error spanning “multiple orders of magnitude”.

    Constraining these, as much as possible, by factoring in models of plausible chemical and genetic mechanisms, results, they conclude, in the finding “that there is a substantial probability that we are alone”.

    The Fermi Paradox is named after physicist Enrico Fermi, who noted in 1950 that there are so many stars, just in the Milky Way, that given the age of the universe even a small probability that intelligent life has evolved would mean that their existence should be plain to humanity by now.

    Yet, he continued, in terms of evidence, we have squat, which, given the probability of intelligent life emerging, is odd. Hence the paradox. “Where are they?” he asked.

    The Drake Equation, formulated by American astronomer Frank Drake in 1961, attempts to place an analytical framework around Fermi’s contention, by estimating the number of intelligent civilisations that exist in the universe, regardless of the fact that we can’t see them.

    In the equation, N represents the number of civilisations within the Milky Way capable of emitting detectable electromagnetic signals. The number is determined by the other factors in the model, which express the rate of suitable star formation, the fraction of those stars with exoplanets, the number of those planets suitable for life and the number on which life actually appears.

    That total is then further reduced by adding in other refinements – the number of life-bearing planets on which intelligence emerges, the number of those that produce technology capable of emitting signals into space, and the number of those that actually go ahead and do so.

    It’s all very impressive, but “sciencey” rather than scientific. Sandberg, Drexler and Ord gleefully quote US astronomer Jill Tarter, who described the Drake Equation as “a wonderful way to organise our ignorance”.

    The problem with the way the equation is usually wielded, the researchers argue, is that the parameters assigned to most of the various elements represent simply best guesses – and those guesses, furthermore, are heavily influenced by whether the person making them is optimistic or pessimistic about the chances of intelligent life existing. The result, they note, often involves well-estimated astronomical numbers multiplied by ad hoc figures.

    They quote another US astronomer, Steven J. Dick: “Perhaps never in the history of science has an equation been devised yielding values differing by eight orders of magnitude … each scientist seems to bring his own prejudices and assumptions to the problem.”

    Dick, they note, was being nice. Many outcomes from Drake Equation calculations yield probabilities that range over hundreds of orders of magnitude.

    In a not altogether unrelated sidebar, the researchers acknowledge a recent calculation by Swedish-American cosmologist Max Tegmark, estimating the chances of intelligent civilisations arising in the universe.

    Tegmark assumes there is no reason two intelligent civilisations should be any particular distance from each other, and then argues that – given the Milky Way is a minuscule fraction of the observable universe, which is itself only a tiny part of the universe beyond what we can see – it is unlikely that two intelligent civilisations would arise in the same observable universe. Thus, to all intents and purposes, we are very probably alone.

    Sandberg, Drexler and Ord use a different approach in their modelling, incorporating current scientific uncertainties that produce values for different parts of the equation ranging over tens and hundreds of orders of magnitude. Some of these concern critical questions regarding the emergence of life from non-living material – a process known as abiogenesis – and the subsequent likelihoods of early RNA-like life evolving into more adaptive DNA-like life.

    Then there is the essential matter of that primitive DNA-like life undergoing the sort of evolutionary symbiotic development that occurred on Earth, when a relationship between two different types of simple organisms resulted in the complex “eukaryotic” cells that constitute every species on the planet more complicated than bacteria.

    The results are depressing enough to send a thousand science-fiction writers into catatonic shock. The Fermi Paradox, they find, dissolves.

    “When we take account of realistic uncertainty, replacing point estimates by probability distributions that reflect current scientific understanding, we find no reason to be highly confident that the galaxy (or observable universe) contains other civilizations,” they conclude.

    “When we update this prior in light of the Fermi observation, we find a substantial probability that we are alone in our galaxy, and perhaps even in our observable universe.

    “‘Where are they?’ — probably extremely far away, and quite possibly beyond the cosmological horizon and forever unreachable.”

    See the full article here.


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  • richardmitnick 1:50 pm on June 22, 2018 Permalink | Reply
    Tags: Fermi Paradox, , , Where are they?   

    From SETI Institute: “If Extraterrestrials are out there, why haven’t we found them?” 

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    From SETI Institute

    Jun 18, 2018
    Seth Shostak, Senior Astronomer

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    The Fermi Paradox, named for Dr. Enrico Fermi, describes the apparent contradiction between the lack of evidence of extraterrestrial civilizations and the high probability that such alien life exists. AP

    “Where is everybody?”

    For those who want to understand why we haven’t found any space aliens, the Fermi Paradox is as popular as cheeseburgers. First proposed by physicist Enrico Fermi in 1950, this perennial head-scratcher rests on the idea that it would take only a few tens of millions of years for an advanced civilization to colonize the Milky Way — leaving their mark on every last star system in the galaxy.

    So why hasn’t some ambitious race of aliens done that? After all, the Milky Way is three times older than Earth, so they’ve had plenty of opportunity to finish the project. We should see outposts of someone’s galactic empire in every direction. Why don’t we?

    As Fermi put it, “Where is everybody?”

    A Russian physicist named A.A. Berezin recently addressed this cosmic conundrum in a short paper. He thinks he knows why we haven’t espied aliens. Mind you, he’s not the first. The Fermi Paradox has prompted dozens if not hundreds of explanations. One possibility is that colonizing the galaxy is simply too costly. Or maybe alien societies are out there, but we lack the instruments to find them. Others favor the idea that extraterrestrials find Homo sapiens inconsequential and juvenile — so they keep a low profile and avoid us.

    Berezin suggests something else. He presumes that at some point in the 13.8 billion years since the Big Bang, an extraterrestrial civilization managed to develop the capability to travel between the stars. Soon thereafter, they embarked on a project to spread out. But as they — or their robot underlings — took over the galaxy, they eradicated everyone else. Some of this might have been inadvertent, in the same way that construction crews mindlessly obliterate ants.

    Does this sound like a variation on Douglas Adams’ “Hitchhiker’s Guide to the Galaxy,” in which Earth is unintentionally destroyed to make way for a hyperspace bypass? Well, it’s the same basic idea. But unlike Adams’ story, Berezin’s doesn’t make much sense. To begin with, it’s unclear how this suggestion really differs from the original paradox. If some ancient society of Galactans took over our galaxy (and maybe all the nearby galaxies too — there’s been time enough), why don’t we see evidence of that?

    By 200 A.D., the Roman Empire had infested nearly all the lands edging the Mediterranean. If you were living within the empire, you’d definitely know it — you could find fluted architecture just about everywhere. So if the Galactans have been all over the place, why don’t we notice? In addition, these hypothesized alien colonists couldn’t just sweep through the Milky Way once and leave it at that. A new species — such as Homo sapiens — might arise at any time, offering a new challenge to imperial dominance and forcing the Galactans to clean house again.

    Keeping control of the galaxy would be an endless project, and one that couldn’t be managed from some central “headquarters.” Even at the speed of light, it takes tens of thousands of years to get from one random spot in the Milky Way to another. Compare that to the response time for Rome — the time between learning that there was trouble afoot and getting their armies in place to confront it. That was typically weeks, not tens of thousands of years.

    Ask yourself: Would the Roman Empire have existed if the legions took centuries or more to trudge to Germania every time the troublesome Alemanni crossed the Rhine? Germania would cease being Roman before you could say “barbarian.”

    It seems clear that Galactans would have to adopt the Roman strategy: Station some defensive infrastructure throughout the Milky Way so it’s possible to deal with problems quickly. Sounds easy, but it would present a difficult logistical problem. How do you adequately maintain and update such a massive network when travel times are measured in millennia?

    Berezin’s idea of how to resolve the puzzle presented by the Fermi Paradox seems neither more convincing nor more plausible than many of the others. It replaces one paradox with another by arguing that the galaxy is, indeed, inhabited everywhere by a pervasive culture that presumably sprang up billions of years ago but somehow manages to evade all our detection efforts.

    The paradox continues to fuel many lunchtime conversations, which at least is a nice diversion from gossip or politics. But if we someday find a signal from space, Fermi’s question will become nothing more than an historical curiosity — a bit of misplaced musing that confounded Homo sapiens for a few decades.

    Meanwhile the aliens — and who could doubt they exist? — keep their own company.

    Originally published at https://www.nbcnews.com/mach/science/if-space-aliens-are-out-there-why-haven-t-we-ncna881951

    See the full article here .


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  • richardmitnick 10:43 am on February 2, 2017 Permalink | Reply
    Tags: , , Atmospheres can protect and nurture or they can destroy, “L” is for the longevity of a potentially civilized intelligent world, , , , , Fermi Paradox, , , The fate of Earth is indeed in our hands   

    From Many Worlds: “Do Intelligent Civilizations Across the Galaxies Self Destruct? For Better and Worse, We’re The Test Case” 

    NASA NExSS bloc

    NASA NExSS

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    Many Worlds

    2017-02-01
    Marc Kaufman

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    The Eastern Seaboard as seen from the International Space Station in 2012. (NASA)

    In 1950, while working at Los Alamos National Laboratory, renowned physicist Enrico Fermi was lunching with colleagues including Edward Teller, Herbert York an Emil Konopinski. The group talked and laughed about a spate of recent UFO reports during the meal, as well as a cartoon about who might be stealing garbage can top.

    A bit later in the meal Fermi famously asked more seriously, “Where are they?” Sure, there were many bogus reports back then about alien flying saucers, but Fermi was asking what has turned out to be a significant and long-lasting question.

    If there are billions of exoplanets out there — as speculated back then but proven now — why have there been no bona fide reports of advanced extraterrestrials visiting Earth, or somehow leaving behind their handiwork?

    Many answers have been offered in the following decades — that we are alone in the universe, that the distances between solar systems are too great to travel, that Earth became home to life early in the galaxy’s history and other planets are only now catching up, that life might be common in the universe but intelligent life is not.

    I would like to focus on another response, however, one that came to mind often while reading a new book by the former holder of the astrobiology chair at the Library of Congress, planetary scientist David Grinspoon.

    This potential explanation is among the most unsettling: that intelligent and technologically advanced beings are likely to ultimately destroy themselves. Along with the creativity, the prowess and the gumption, intelligence brings with it an inherent instinct for unsustainable expansion and unintentional self destruction.

    I should say right off that this is not a view shared by Grinspoon. His Earth in Human Hands, in fact, argues with data and conviction that humans are more likely than not to ultimately find ways to work together and avoid looming global threats from climate change, incoming asteroids, depleting the ozone layer and myriad other potential sources of mass extinction.

    But his larger point is the sobering one: that the fate of Earth is, indeed, in our hands. We humans are a force shaping the planet that is as powerful as a ring of volcanoes, a giant impactor from space, the long-ago rise of lifeforms that could, and did, dramatically change our atmosphere and along the way caused near global extinction.

    It may sound odd, but as he sees it we are now the planet’s most powerful and consequential force of nature.

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    Since the Industrial Revolution and the spread of technology over the past 200 years, humans have become the dominant force on the planet, says David Grinspoon, the first Chair in Astrobiology at the Library of Congress. (Credit: Tony Steele)

    “What I’ve sought to do is describe what is reality on our planet,” Grinspoon told me. “Some people have been hostile and told me it’s arrogant to say humans have so much control over the fate of the planet, and I agree that it’s a sobering thing.”

    But the Earth has been and will be dramatically changed by us. The big question for the future is whether change can be for the better, or will it be unsustainable and for the worse.”

    While Grinspoon’s major themes involve competing paths for the future of our planet, they consistently are based on and informed by knowledge gained in recent decades about planets in our solar system and those very far away. The logic and track record of the search for intelligent life beyond Earth (SETI) also plays a role, as does the author’s relationships — initially via family in childhood — with Carl Sagan and some of the scientists he mentored.

    For instance, Grinspoon has studied Venus and the evolution of its atmosphere. He says that an understanding of the runaway greenhouse effect that created surface temperatures of 800 degrees F has been instumental in the study of climate change on Earth.

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    David Grinspoon is a senior scientist at the Planetary Science Institute, and the author of “Earth in Human Hands.”

    Similarly, the disappearance of much of the Martian atmosphere left the once warmer planet frigid and likely lifeless. Sagan’s work on the dust storms of Mars, which have the effect of making the planet colder still, was an early scientific foray into understanding the importance of atmosphere and climate on a potential biosphere. So was Sagan’s work on the possible effects of atomic war — the globally life-destroying “nuclear winter.”

    The clear inference: Planetary atmospheres can change, as ours is doing now with major buildups in carbon dioxide. Atmospheres can protect and nurture, or they can destroy.

    And Exhibit A is the three rocky solar system planets in what is a slightly expanded habitable zone. But only one supports life.

    The buildup of carbon dioxide in the atmosphere and oceans since the onset of the industrial revolution, Grinspoon writes, is a prime example of how intelligent people and their technology can unintentionally have a huge impact on nature and the planet. The jury remains out as to how humanity will respond.

    But Grinspoon also points to the way that nations around the globe responded to the discovery that the ozone layer was being depleted as an example of how humanity can repair unintentional yet potentially extinction-threatening challenges.

    It took a while, but the artificial refrigerants — chlorofluorocarbons (CFCs) — causing the damage were ultimately curtailed and then banned, and there are signs that the worrisome holes in the ozone layer are if not shrinking, at least no longer growing.

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    The Drake equation, created by astronomer Frank Drake in 1961, assesses the probability of how many planets in our galaxy might have civilizations that can communicate. The last factor — the “L” for longevity — is considered key. Drake was one of the founders of SETI, and its effort to detect signals from intelligent life beyond Earth.

    This brings us back to the Fermi paradox, and the apparent absence of signs of extraterrestrial intelligence.

    Fermi, and many others, have assumed that successful, technological civilizations elsewhere would have the desire and ultimately know-how to expand beyond their original planet and colonize others. Indeed, early SETI gatherings here and in the former Soviet Union took that drive to expand for granted, a reflection of attitudes of the times.

    This presumed drive to colonize was often discussed as either a kind of biological imperative or an acknowledgement that these “intelligent” civilizations are likely to have seriously damaged their own planets through unsustainable and hazardous growth. Either way, they would be on the move.

    Yet after more than a half century of listening for signals from these presumed intelligent and mobile beings, the SETI effort to detect such life via radio telescopes has come up empty. There are many potential reasons why, but let’s focus on the one introduced earlier.

    The pioneering Drake equation, first put forward in 1961, attempts to assess the probability of finding intelligent civilizations beyond Earth based on factors such as rate of star formation in the galaxy, the number of planets formed and then the percentage with life, then the number with complex life and finally intelligent and technologically-sophisticated life. But it’s the “L” at the end of the equations, says Grinspoon, that is widely considered the most important.

    SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA
    SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA

    The “L” is for the longevity of a potentially civilized, intelligent world, or “the length of time over which such civilizations release detectable signals.”

    Of all the components of the Drake equation, which is filled with unknowns and partially known estimates, L is no doubt the least well defined. After all, no extraterrestrial life, and certainly no intelligent life, has ever be detected.

    Yet as describe by Grinspoon, “L” — which for Earth is about 200 years now — is the key.

    “Let’s say that it’s impossible for a civilization with very powerful technology to last for 10,000 years, or even 1,000 years. That makes the likelihood of ever making contact with them vanishingly small even if life and intelligence are out there. The chances of them being close enough to detect and communicate with are pretty much nil.”

    If the opposite is true, if it’s possible for a civilization to get over their technological adolescence, then they ought to be detectable. Actually, they could last for millions of years using their technology to enhance and protect the planet.”

    Planets face all kinds of dire threats, and catastrophes and extinctions are the rule. But if technology can be used intentionally for the benefit the planet — like protecting it from an asteroid or avoiding the next Ice Age – longevity would clearly improve greatly.”

    This interstellar view, he says, helps to see more clearly what is happening on Earth. Now that through our technologies we have become the prime movers regarding the planet’s health and safety, it is really up to us as a species to choose between allowing these “advances” to knowingly or unintentionally harm the planet, or to consciously use technology to make it better.

    Grinspoon does not see our current century as one when the effects of technology are likely to be intentionally positive. But he does see the movement towards a more sustainable planet to be irreversible, whatever blips might come our way. What’s more, he said, fossil fuels will be largely gone by 2100 and there’s reason to believe the world’s human population will have stabilized — two enormous changes that favor a longer-lived human civilization.

    “The long-held view that humans will always expand, that they will maintain that biologically primitive imperative, that growth is always good — it’s interesting to wonder if those assumptions aren’t inherently wrong,” he said.

    “I suggest that true ‘intelligence’ able to sustain itself involves an inherent questioning of those values, and that a more measured and strategic growth pattern, or even material stasis might be values that come with a more universal intelligence.”

    Whether that intelligence is on Earth or many hundreds of light years away.

    See the full article here .

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    About Many Worlds

    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 2:58 pm on January 18, 2015 Permalink | Reply
    Tags: , , Fermi Paradox,   

    From NYT: “Is a Climate Disaster Inevitable?” 

    New York Times

    The New York Times

    JAN. 17, 2015
    ADAM FRANK, University of Rochester

    OUR galaxy, the Milky Way, is home to almost 300 billion stars, and over the last decade, astronomers have made a startling discovery — almost all those stars have planets. The fact that nearly every pinprick of light you see in the night sky hosts a family of worlds raises a powerful but simple question: “Where is everybody?” Hundreds of billions of planets translate into a lot of chances for evolving intelligent, technologically sophisticated species. So why don’t we see evidence for E.T.s everywhere?

    1
    Patrick Leger

    The physicist Enrico Fermi first formulated this question, now called the Fermi paradox, in 1950. But in the intervening decades, humanity has recognized that our own climb up the ladder of technological sophistication comes with a heavy price. From climate change to resource depletion, our evolution into a globe-spanning industrial culture is forcing us through the narrow bottleneck of a sustainability crisis. In the wake of this realization, new and sobering answers to Fermi’s question now seem possible.

    Maybe we’re not the only ones to hit a sustainability bottleneck. Maybe not everyone — maybe no one — makes it to the other side.

    Since Fermi’s day, scientists have gained a new perspective on life in its planetary context. From the vantage point of this relatively new field, astrobiology, our current sustainability crisis may be neither politically contingent nor unique, but a natural consequence of laws governing how planets and life of any kind, anywhere, must interact.

    The defining feature of a technological civilization is the capacity to intensively “harvest” energy. But the basic physics of energy, heat and work known as thermodynamics tell us that waste, or what we physicists call entropy, must be generated and dumped back into the environment in the process. Human civilization currently harvests around 100 billion megawatt hours of energy each year and dumps 36 billion tons of carbon dioxide into the planetary system, which is why the atmosphere is holding more heat and the oceans are acidifying. As hard as it is for some to believe, we humans are now steering the planet, however poorly.

    Can we generalize this kind of planetary hijacking to other worlds? The long history of Earth provides a clue. The oxygen you are breathing right now was not part of our original atmosphere. It was the so-called Great Oxidation Event, two billion years after the formation of the planet, that drove Earth’s atmospheric content of oxygen up by a factor of 10,000. What cosmic force could so drastically change an entire planet’s atmosphere? Nothing more than the respiratory excretions of anaerobic bacteria then dominating our world. The one gas we most need to survive originated as deadly pollution to our planet’s then-leading species: a simple bacterium.

    The Great Oxidation Event alone shows that when life (intelligent or otherwise) becomes highly successful, it can dramatically change its host planet. And what is true here is likely to be true on other planets as well.

    But can we predict how an alien industrial civilization might alter its world? From a half-century of exploring our own solar system we’ve learned a lot about planets and how they work. We know that Mars was once a habitable world with water rushing across its surface. And Venus, a planet that might have been much like Earth, was instead transformed by a runaway greenhouse effect into a hellish world of 800-degree days.

    By studying these nearby planets, we’ve discovered general rules for both climate and climate change. These rules, based in physics and chemistry, must apply to any species, anywhere, taking up energy-harvesting and civilization-building in a big way. For example, any species climbing up the technological ladder by harvesting energy through combustion must alter the chemical makeup of its atmosphere to some degree. Combustion always produces chemical byproducts, and those byproducts can’t just disappear. As astronomers at Penn State recently discovered, if planetary conditions are right (like the size of a planet’s orbit), even relatively small changes in atmospheric chemistry can have significant climate effects. That means that for some civilization-building species, the sustainability crises can hit earlier rather than later.

    Even if an intelligent species didn’t rely on combustion early in its development, sustainability issues could still arise. All forms of intensive energy-harvesting will have feedbacks, even if some are more powerful than others. A study by scientists at the Max Planck Institute in [ for???]Jena, Germany, found that extracting energy from wind power on a huge scale can cause its own global climate consequences. When it comes to building world-girdling civilizations, there are no planetary free lunches.

    This realization motivated me, along with Woodruff Sullivan of the University of Washington, to look at sustainability in its astrobiological context. As we describe in a recent paper, using what’s already known about planets and life, it is now possible to create a broad program for modeling co-evolving “trajectories” for technological species and their planets. Depending on initial conditions and choices made by the species (such as the mode of energy harvesting), some trajectories will lead to an unrecoverable sustainability crisis and eventual population collapse. Others, however, may lead to long-lived, sustainable civilizations.

    Such research is, however, more than prospecting for scientific curiosities.

    One answer to the Fermi paradox is that nobody makes it through — that climate change is fate, that nothing we do today matters because civilization inevitably leads to catastrophic planetary changes. But our models may show that isn’t the case.

    By studying sustainability as a generic astrobiological problem, we can understand if the challenge we face will be like threading a needle or crossing a wide valley. Answering this question demands a far deeper understanding of how planets respond to the kind of stresses energy-intensive species (like ours) place on them. It’s an approach no different from that of doctors using different kinds of animals, and their molecular biology, to discover cures for human disease.

    With this perspective, we also gain an essential truth. We are one form of life, on one planet, in a universe of countless planets. Through hard-won scientific gains, we’ve begun discovering the patterns and laws governing planets together with the life they host. Ten thousand years from now the Democrats and the Republicans and their squabbles over climate change will be long gone. But the laws of planets and life we’re now revealing won’t have changed. Not on this world or any other.

    See the full article here.

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