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Researchers Say The Aliens Are Silent Because They Are Extinct (theconversation.com) 559

HughPickens.com writes: The Conversation reports that according to research by Dr. Charles Lineweaver and Dr. Aditya Chopra, a plausible solution to Fermi's paradox is near universal early extinction of life on exoplanets, which they have named the Gaian Bottleneck. "The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens," says Chopra. "The mystery of why we haven't yet found signs of aliens may have less to do with the likelihood of the origin of life or intelligence and have more to do with the rarity of the rapid emergence of biological regulation of feedback cycles on planetary surfaces." According to the researchers, most early planetary environments are unstable. To produce a habitable planet, life forms need to regulate greenhouse gases such as water and carbon dioxide to keep surface temperatures stable. About four billion years ago, Earth, Venus and Mars may have all been habitable. However, a billion years or so after formation, Venus turned into a hothouse and Mars froze into an icebox. Even if wet rocky Earth-like planets are in the "Goldilocks Zone" of their host stars, it seems that runaway freezing or heating may be their default fate. Large impactors and huge variation in the amounts of water and greenhouse gases can also induce positive feedback cycles that push planets away from habitable conditions. The difference on Earth may be that as soon as life became widespread on our planet, the earliest metabolisms began to modulate the greenhouse gas composition of the atmosphere. "The emergence of life's ability to regulate initially non-biological feedback mechanisms could be the most significant factor responsible for life's persistence on Earth, conclude Lineweaver and Chopra. "Even if life does emerge on a planet, it rarely evolves quickly enough to regulate greenhouse gases, and thereby keep surface temperatures compatible with liquid water and habitability."
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Researchers Say The Aliens Are Silent Because They Are Extinct

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  • It's a f... (Score:4, Funny)

    by AchilleTalon ( 540925 ) on Wednesday June 08, 2016 @06:04AM (#52273255) Homepage
    It's a fucking good reason to be silent, I admit.
    • Re:It's a f... (Score:5, Interesting)

      by Rei ( 128717 ) on Wednesday June 08, 2016 @08:03AM (#52273663) Homepage

      Except that it ignores subsurface oceans, which seem to be quite stable over long timeperiods and quite likely to be very abundant in the universe.

      Sure, a species evolved to an undersea environment faces challenges in getting to their surface and beyond... but if we can get out of this deep gravity well after such a (geologically) short period of time after our species' evolution, sentient species in subsurface oceans with hundreds of millions or billion years on their "hands" would surely deal with the technical difficulties.

      And of course there's also the possibility of LNAWKI, but let's just stick with LAWKI for now.

      My personal suspicion is that a wide variety of factors work together to keep complex life rather rare on a per-planet basis, great distances dilute any signals from any that do achieve sentience, and the speed of light and difficulty of propagating a civilization outward at near that limit keeps the vast majority far away. Basically, rarity + dilution. But that's just my suspicion.

      • Re:It's a f... (Score:5, Interesting)

        by silentcoder ( 1241496 ) on Wednesday June 08, 2016 @08:44AM (#52273829)

        My personal theory is that the most likely thing for any intelligent and technologically capable alien race to be doing is exactly what *we* are doing. Listen, and with a small budget - so only listening to a very small part of the spectrum from a tiny part of the sky. That golden record on voyager 1 is about the last major attempt we made at sending anything and it wasn't a very sensible one.

        But if that was what economics led to here, why would we assume it would have other outcomes elsewhere ? Literally the only experimental sample of a technologically capable space-faring race we have - did this one.

        So it's perfectly likely that there dozens of alien races within easy communications range of us all making a half-hearted attempt at listening and waiting for one of the others to talk first. All of them, in fact, hoping the outsource the expense of sending high-powered signals into a void where you don't know if anybody is listening, don't know if anybody who was listening would be able to understand it and don't even know in which direction to aim - to one of the others.

        Exactly because sending messages is so incredibly difficult technically, and expensive, they may all have opted to just listen instead and, like us, hope that one of the others will figure out transmission first so they can justify the budget to build a transmitter to reply with.

        • Re:It's a f... (Score:4, Interesting)

          by robi5 ( 1261542 ) on Wednesday June 08, 2016 @11:42AM (#52275113)

          > My personal theory is that the most likely thing for any intelligent and technologically capable alien race to be doing is exactly what *we* are doing.

          Exactly - making ourselves go extinct over the cosmological blip of a few hundred years, by systematically undermining our own life conditions (us: global warming); by squandering non-replenishable resources (oil, gas, rare earth elements); by maintaining nation states that act like we don't share a planet (Putin's Russia, North Korea, China, Arab / Islam countries, USA etc.); by creating weapons that allow more and more destructive potential per user (nuclear, biological and autonomous weapons); and by resisting the completion of the surveillance police state and precrime, which are pretty much the only means to ensure that terrorists are killed before they can fake some nuclear attack, setting off WWIII, or release some plague that wipes out half of mankind and destroys economy as we know it.

          Once we global-warm, war or terrorism ourselves back into a pre-technological tribe, we'll no longer have the chance for an industrial and thus technological revolution, for we have already used up most of the easily accessible oil and gas; no more radio telescopes sent to space.

          Maybe we can't observe other intelligent life simply because chances are, any transmission is puny and fleeting on the cosmological scale, making reception incredibly unlikely. However maybe there are intelligent creatures that enjoyed their brief technological triumph, only to be followed by millions of years of an eternal Stone Age in the optimistic doom scenario when large bodied intelligent creatures can even survive their own technological windfall.

          The rare few civilizations that survive the high mortality rate of technological infancy might evolve to such superpowers that they have unimaginable matter manipulation and computational capabilities in their hand. We, at such premature stage, already build vast, large simulations even without really trying (called games or machine learning environments). They (and maybe we) then go on building new universes which themselves beget alife, some of which may become powerful to build their own simulations. Then, we can conclude that believing that we are World #1 is the same anthropocentric view and hubris as geocentrism was a moment ago. Most probably we're currently on the bottom of a deep stack, hoping for adequate power redundancy and backup procedures in all layers above.

          In conclusion, most of the fellow technological civilizations are behind us or ahead of us (time), or above us and maybe at some point, below us (simulation stack). All except the last of these are very unlikely to encounter and detect.

      • by DigiShaman ( 671371 ) on Wednesday June 08, 2016 @08:52AM (#52273849) Homepage

        Or we're all living in a simulator and the 'alien' expansion pack hasn't been released....yet.

      • Re:It's a f... (Score:5, Insightful)

        by Applehu Akbar ( 2968043 ) on Wednesday June 08, 2016 @08:58AM (#52273893)

        All speculation about alien life tends to founder on the issue of small sample size, but already we observe that our machines 'like' space and extraterrestrial surface environments much better than our squishy carbon-based bodies do. So perhaps the leading candidate for LNAWKI would be something like our silicon-based emissaries. If the same process has been going on elsewhere we may find that (a) the most likely aliens we encounter will be machines, and (b) the encounter will be by our own machines.

        • LNAWKI what is that supposed to mean?
          The only "useful" cough cough google results are two /. posts.

          • Re: (Score:2, Informative)

            by Rei ( 128717 )

            LAWKI = Life As We Know It
            LNAWKI = Life Not As We Know It

            There are lots of variants of the latter, while the former is pretty standardized.

          • Re:It's a f... (Score:5, Informative)

            by Applehu Akbar ( 2968043 ) on Wednesday June 08, 2016 @10:37AM (#52274581)

            Unfortunately, these geek acronyms tend to be English-specific. Some others you will encounter here:

            RTKBA - Right to keep and bear arms;
            TEOTWAWKI - The end of the world as we know it;
            DYKWIA - "Do you know who I am?"
            SJW - Social justice warrior

      • Sure, a species evolved to an undersea environment faces challenges in getting to their surface and beyond...

        It would be much easier for a sentient undersea creature like an octopus to colonize the surface of their own planet than it would be for us to colonize the moon. As an added advantage, once a creature like the octopus has colonized the surface of their planet, they would already have most of the required technology to colonize other worlds. They would already have space suits, self-contained habitats, etc... The biggest problem I see (with an obvious LAWKI bias) is that most of our technology is electri

        • Re: (Score:3, Interesting)

          by Rei ( 128717 )

          On the other hand, some things can be easier underwater - for example, moving heavy objects (with buoyancy), long distance communication, etc. And of course the main drivers for advancement still exist, things like farming, hunting, armaments, defense, etc.

          Electricity still works underwater (though AC not as well, and of course insulation is important). The same basic lines of progression work underwater. You can still make a "potato battery" type cell underwater with native copper, you can move lodeston

      • by Maow ( 620678 )

        Except that it ignores subsurface oceans, which seem to be quite stable over long timeperiods and quite likely to be very abundant in the universe.

        Agreed - and since it seems life on earth began in the oceans, it's a very likely proposition.

        Sure, a species evolved to an undersea environment faces challenges in getting to their surface and beyond... but if we can get out of this deep gravity well after such a (geologically) short period of time after our species' evolution, sentient species in subsurface oceans with hundreds of millions or billion years on their "hands" would surely deal with the technical difficulties.

        This I disagree with. An intelligent ocean-based life form is going to have to find a way to work with steel to get to space, and that can't be done below the surface in any way I've ever been able to imagine.

        Without the ability to smelt iron / steel, etc. they just aren't going to be able to migrate on to land, never mind into the atmosphere, never mind space.

        I'd be interested in any ideas you have on how they mi

    • by rtb61 ( 674572 )

      Apart from the illogic of an advance long lived species desire to remain bound to an unstable planetary surface, with variable stellar output and not being able to get out of the way of undeflectably large impacts. The greater stability of mobile orbital colonies and say city ships makes it logical, that while more primitive planetary bound elements of the society went extinct, the more advanced elements simply continued within more replaceable enduring environments. Not to mention the very strange idea, t

  • by invictusvoyd ( 3546069 ) on Wednesday June 08, 2016 @06:09AM (#52273263)

    The mystery of why we haven't yet found signs of aliens may have less to do with the likelihood of the origin of life or intelligence and have more to do with the rarity of the rapid emergence of biological regulation of feedback cycles on planetary surface

    Monty Python

    err .. I mean It's the distance .. the distance

    • Re:Its... (Score:5, Insightful)

      by khasim ( 1285 ) <brandioch.conner@gmail.com> on Wednesday June 08, 2016 @06:17AM (#52273283)

      Yep, it's the distance.

      And whatever constitutes "teeming with aliens". Is that 10 planets per galaxy? 100? 1,000?

      And the time involved. How long ago did life start on Earth? How many mass extinctions have there been? Would ANY of those have been detected by aliens on their home planet using technology equivalent to ours?

      The Fermi "paradox" is based upon alien expansion. Which is, in turn, based upon tech advances that we don't have.

      The galaxy could be "teeming with aliens" that we cannot detect and that we cannot reach with our technology. Nor can they detect us or reach us.

      • by Anonymous Coward on Wednesday June 08, 2016 @08:04AM (#52273665)

        For four billion years, life on Earth was microscopic blobs of goo.

        Then 600 million years ago - BAM - complex life emerged pretty much in the blink of an eye.

        We have no idea how likely that transition to complex life 600 million years ago was - we have a sample size of ONE.

        Now go back an read my first sentence: For four billion years, life on Earth was microscopic blobs of goo.

        That four billion years was about half the expected lifetime of the Earth. The probability that complex life evolves may very well be infinitesimally small. WE DON'T KNOW.

        Believing the universe must be teeming with intelligence is based on nothing more than faith.

        • Re: (Score:3, Interesting)

          by Dan1701 ( 1563427 )

          For four billion years, life on Earth was microscopic blobs of goo.

          Then 600 million years ago - BAM - complex life emerged pretty much in the blink of an eye.

          We have no idea how likely that transition to complex life 600 million years ago was - we have a sample size of ONE.

          Now go back an read my first sentence: For four billion years, life on Earth was microscopic blobs of goo.

          That four billion years was about half the expected lifetime of the Earth. The probability that complex life evolves may very well be infinitesimally small. WE DON'T KNOW.

          Believing the universe must be teeming with intelligence is based on nothing more than faith.

          Actually, the odds are worse than that. Mass extinctions have happened with monotonous regularity in the history of the world, and only comparatively recently have life forms evolved with internal skeletons that enabled them to get to be quite big. Insects and arthropods probably don't get big enough to carry large enough brains to become intelligent, but arthropods seem to evolve a lot more easily than do vertebrates.

          Even when you look at vertebrates, a tendency to evolve big brains seems to be exclusively

          • Dinosaurs seem to have been ancestrally warm-blooded, ditto crocodilians and so on, but dinosaurs plot right on the expected brain to body size ratio that reptiles have.

            You seem to be ignoring absolute brain size here. Especially since small dinosaurs (you know, like parrots) have a brain:body mass ratio considerably larger than humans do (1:12 for small birds, 1:40 for humans).

            In any case, brain to body mass ratio is just part of the answer, not a complete picture of the issue of intelligence.

      • Yep, it's the distance.

        And whatever constitutes "teeming with aliens". Is that 10 planets per galaxy? 100? 1,000?

        And the time involved. How long ago did life start on Earth? How many mass extinctions have there been? Would ANY of those have been detected by aliens on their home planet using technology equivalent to ours?

        The Fermi "paradox" is based upon alien expansion. Which is, in turn, based upon tech advances that we don't have.

        The galaxy could be "teeming with aliens" that we cannot detect and that we cannot reach with our technology. Nor can they detect us or reach us.

        To be fair, if we never hard the dark ages and big stretches of time that religion was in charge and very little actual progress was made we would probably be way ahead of where we are now.

      • They might even be communicating with each other but using a communications method that we can't detect. Imagine if you had a medieval civilization on a planet and an advanced civilization blasted radio waves all over to communicate. The medieval folks wouldn't have the technology to intercept and interpret the radio waves so the advanced civilization would be invisible to them.

      • Re:Its... (Score:5, Informative)

        by Dan1701 ( 1563427 ) on Wednesday June 08, 2016 @09:59AM (#52274289)

        One thing to bear in mind is that life here existed in the form of anaerobic bacteria for a staggeringly long time. Photosynthesis began as a way to split hydrogen sulphide into useful hydrogen ions and a useless waste product of elemental sulphur, which was also usefully inert. Early photosynthesis therefore didn't require much in the way of biochemical sophistication to operate; the waste sulphur is where some large sulphur deposits originated.

        That changed with a mutation which let the photosynthesis split not hydrogen sulphide, but water into useful hydrogen and (to anaerobic bacteria) highly toxic and dangerous oxygen. That initially wasn't all that big a problem to early water-splitters; the oceans they were in were rich in iron-II salts which readily absorbed oxygen to become insoluble iron-III salts (this is where the banded iron rock formations come from).

        Everything changed when most of the iron-II in solution in the early earth's oceans was used up. Oxygen levels slowly rose, and virtually all bacterial species either adapted or went extinct. Oxygen is toxic to most bacteria.

        I would hypothesise that most alien worlds either never make the switch from anaerobic atmosphere to aerobic one, or fail to establish a homeostatic oxygen-nitrogen atmosphere quickly enough and effectively enough to become self-regulating.

    • Re:Its... (Score:5, Funny)

      by PolygamousRanchKid ( 1290638 ) on Wednesday June 08, 2016 @07:06AM (#52273431)

      Monty Python

      Maybe the aliens aren't quite dead yet . . . they are merely resting?

      Tired and shagged out after a long squawk . . . ?

      Or it's intern-planetary censorship . . . their governments are blocking them from contacting us . . . ?

      • by Zocalo ( 252965 )
        No, that's not it. They are clearly pining for the fjords. It's not been quite the same since Magrathea shut up shop. That Slartibartfast fellow just to do some amazing work on the crinkly bits...
  • "Frastra In the fire storms of Frastra, they say, life begins at 40,000 degrees." - The Hitchhiker's Guide to the Galaxy
  • by dohzer ( 867770 )

    Or extinct because their suns have died. Either or.

  • Rarely Evolves?? (Score:2, Insightful)

    by Anonymous Coward

    "Even if life does emerge on a planet, it rarely evolves quickly enough to regulate greenhouse gases......"

    Rarely? What is the sample size for the statistics?

    • I wonder about that, too, because of data pointing to panspermia [technologyreview.com]. If they are evolved enough to survive interstellar travel, then they might also be evolved enough to help stabilize a planetary ecosystem.
  • "In the long run, we are all dead'. - John Maynard Keynes, A Tract on Monetary Reform
  • by hackertourist ( 2202674 ) on Wednesday June 08, 2016 @06:23AM (#52273305)

    'Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.'

  • by goarilla ( 908067 ) on Wednesday June 08, 2016 @06:26AM (#52273315)

    Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space.

    Coupled with the odds of being alive and intelligent at the right time
    and putting in the resources to make one noticeable (large laser irradiating the sun, dyson sphere, ...) long enough.
    I'm not really that surprised there is yet another plausible factor that makes it hard.

  • The reason is... (Score:5, Interesting)

    by Diac ( 1515711 ) on Wednesday June 08, 2016 @06:28AM (#52273319)

    A good theory I read about somewhere is that the reason we can not find evidence is simply to do with technology either other alien cultures at the point in time we are witnessing there systems have not developed the technology that we can detect or they have moved beyond the need to blast everything in the entire em spectrum out to space.

    How many years have we been detectable by other races and how many years left until our technology gets efficient enough that any trace of our race gets hidden by been simply cleaner with our em pollution.

    Will we cease to exist to other races out there when we become undetectable?

    • Re:The reason is... (Score:5, Interesting)

      by l0n3s0m3phr34k ( 2613107 ) on Wednesday June 08, 2016 @08:25AM (#52273759)
      Looking at our own "ability" to "regulate greenhouse gases", we just might "cease to exist" too. Technically, another civilization would have to be within 130 light-years of us to pick up on our radio signals. Those signals have actually been tamped down recently with the rise in fiber optics...aliens might be able to detect "life" here by spectrographic analysis of our atmosphere, especially if their within 200 light years they might see an unnatural rise of CO2 from the use of coal and the beginning of the Industrial Revolution. But, there aren't very many stars within that radius we think might have any life, much less an advanced technological civilization.

      As for the Fermi issue, IMHO radio signals just degrade too quickly across the vast distances for us to pick up currently (if ever). Even if the theoretical Alcubierre warp drive actually works, it's still only 10x the speed of light. In Star Trek terms, that's just a little over warp 2. Fermi was talking about a time period of millions of years though.
  • by pepsikid ( 2226416 ) on Wednesday June 08, 2016 @06:39AM (#52273349)

    They can be built around any reasonably stable star (especially very long-lived red dwarfs) which has some rubble to rebuild into spacious habitations. No need to seek a proper star or habitable/terraformable planet. No need to genetically warp ourselves or live in underground tunnels like morlocks. The Colonies provide the perfect living conditions for the builder species.

    Communication networks are likely via line-of-sight laser or some means we can't comprehend, so there's no transmissions for us to pick up. Hundreds of millions in number around each star, they're still too wispy to show up at distance as much more than asteroid fields or protoplanet belts. Being self-sufficient, it's no big deal when one colony decides to make the long, slow journey to the next uninhabited star. There, they get busy populating the colonies pre-built by robots sent ahead. The universe is old enough that there has been time for every star in the galaxy to be homesteaded by now.

    We can get started by dismantling our own moon for material, moving on to Mercury and Mars's moons (planets are too big and unhealthy for our biology) until all of the available floating rock has been utilized. The colonies aren't made of girders and sheet steel. They're built by sintering crushed rock in the beam of focused sunlight, building up the superstructure like a gargantuan 3D printer. To simplify energy collection, the second or third generation of colonies are probably towed close to the sun, to minimize the size of PV panels needed.

    • We can get started by dismantling our own moon for material,

      Don't you think we might want to keep it around for tides? Let's just use the asteroids, and maintain the planet as a park or something.

      • It will take millions of years to actually dismantle the moon, so Earth and its tidepool crabs are safe in the long run. We need to start with the moon since it's 12 orders of magnitude closer to home than anywhere else. Good practice for a few centuries. Local transportation can be done efficiently through orbital skyhooks. Then, Mercury is next because power is so accessible there. Other moons and asteroids come later since energy would be harder to collect to run operations.

        There's not going to be any te

        • Mars actually needs a much larger moon, to get it's internal dynamo running again. Without a magnetic field, any long-term habitation is not going to work. It needs something like the mass of Vesta in orbit to get it's core churning again.
          • We do not need Mars! We only need its moons - as an afterthought, at that. Mars is too light to provide proper gravity, too cold, and atmosphere too thin to protect from radiation and meteors. We cannot and would not want to live there. Ya gotta get your head out of the 1950's scifi assumption of living on alien planets. We have Earth, and we'll have manufactured orbital habitats.

    • by 110010001000 ( 697113 ) on Wednesday June 08, 2016 @12:22PM (#52275387) Homepage Journal
      Space nutter detected. Evidence: "Suggests dismantling our moon".
  • by Viol8 ( 599362 ) on Wednesday June 08, 2016 @06:41AM (#52273355) Homepage

    Just some of the things that had to happen for us to be where we are now:

    1) Life had to evolve
    2) Multicelluar life had to evolve (this took a billion years after life itself arose so is probably not a forgone conclusion)
    3) Life had to climb out of the oceans (dolphins might be smart but they won't be building any rockets with their flippers anytime soon)
    4) Suitable intelligence had to evolve. Had it not been for the asteroid the dinosaurs would still be in charge.
    5) Humans had to survive numerous climate changes and if the genetics is to be believed we almost died out and everyone today comes from a very small population who made it.
    6) Farming had to be created to allow people to do something other than hunting and gathering.
    7) For the industrial revolution plenty of freely available energy had to be lying around near the surface - ie coal. You can't melt iron with wood fires.
    8) Someone had to invent radio.

    I'm sure there are dozens of other things that could fit inbetween those points but my basic point is that a technological civilisation than can broadcast information out from his own planey is very VERY unlikely. IMO we could well be the only one surrounded by planets full of the equivalents of bacteria and jellyfish but little more.

    • You can't melt iron with wood fires

      Not in its raw form, however you can make charcoal from wood (burn it with insufficient oxygen) and then use that to smelt iron. The requirement is concentration of energy, but once you have one energy source then eventually you can concentrate it. You can smelt iron in a solar furnace too, though you need to make a lot of glass to a fairly high standard to do it.

      IMO we could well be the only one surrounded by planets full of the equivalents of bacteria and jellyfish but little more.

      The point of TFA is that this is unlikely. Without photosynthesis, early life here would have experienced a run-away greenhouse effect and died

      • Without the right balance after photosynthesis evolved, the oxygen content of the air would have become high enough to kill off all life.

        No. Absolutely not. It would have become high enough to kill off most life. Developing photosynthesis is the hard part. After that, there's a lot more organic matter to work with, and a lot more can happen. Something will mutate to adapt to the new conditions, which are not uniform across the globe.

      • by Viol8 ( 599362 )

        "however you can make charcoal from wood (burn it with insufficient oxygen) and then use that to smelt iron. "

        Yes, fair point. However there simply weren't enough trees around to do it - even in tudor times entire forests had to be grown just for ship wood - which is why the industrial revolution didn't really get going until mass coal production started.

    • You also need a large moon to stabilize the planet's axis, keep the core churning, etc.
    • Except by that measure, we too are fantastically unlikely.
      Humans are made up of hundreds of millions of specialized cells which, in the scant 3-ish billion years since prokaryotes showed up, had to learn to cooperate synergistically. And "learn" in a non-deterministic sense: basically they had to mutate (randomly) into combinations (randomly) and then be stressed (randomly) such that their offspring would demonstrate a competitive advantage...to the order of a hundred million cooperating.

      If you think about

      • All it takes is the right kind of evolutionary stress until civilization can take over. And, as odd as this may sound, religion. It's the only sensible way you can make more than 10 people work together without a strong cultural history in legal proceedings.

    • Just some of the things that had to happen for us to be where we are now:

      This is an interesting list, and as you note, there are all sorts of "other things that could fit in between those points."

      However, your conclusion CANNOT follow, i.e., a technological civilization that can broadcast information is "very VERY unlikely." You have no basis to say it is "unlikely" nor "likely," because we have one data point -- Earth. One cannot extrapolate from one data point.

      And that's why articles like this one always bug me a bit. "Researchers Say the Aliens Are Silent Because They

  • by joh ( 27088 ) on Wednesday June 08, 2016 @06:47AM (#52273375)

    I think there are two other points to consider: First, life and even intelligent life does not necessarily mean technology, or technology at an industrial scale. Maybe just THIS is very, very rare, with civilisations going this way separated by enormous gulfs of time and space. And maybe the universe is full of planets with aliens that have some sophisticated culture, but not at an technological scale that would lead to us being able to detect them.

    Then there's the bottleneck of how long a species can sustain a lifestyle of full-scale industrial technology. Without forking out into space as soon as they can resources will be depleted very soon and then it's too late. Either that culture will end then or will (have to) become much more efficient and low-key, which again lowers the chances of us detecting anything.

    I mean, one very useful aspect of thinking about this is thinking about what is going on here, not there. How long can we sustain this and what do we have to do to sustain it? Maybe we will learn how things tend to go with industrial-scale technological civilisations very quickly, even if too late...

  • Is this Slashdot... (Score:4, Interesting)

    by ControlsGeek ( 156589 ) on Wednesday June 08, 2016 @06:47AM (#52273377)

    Or National Enquirer ?

  • Without the industrial revolution CO2 may have continued its decline and eventually become too low to support life. 150ppm seems about the range where some plants start dying. We got to 180 ppm. Digging up an burning coal helped raise this amount back to a sustainable level.

  • The problem is we don't actually know what to look for. We currently look for worlds where life might be possible that is similar to ours. For all we know the universe is teaming with life but we have no idea how to recognise it as we can't actually get out there and look. It is like looking for a needle in a thousand haystacks when you have no idea what a needle actually looks like or is made of, you could step on it and have no idea you found it.
  • We don't even listen out for SOS morse messages any more, and that was only around for a hundred years or so.

    Any method of contacting an advanced civilisation isn't going to be listened for for more than a few generations before its obsolete and nobody's on the other end anyway. Like trying to send a fax will be in a few decades, or how pagers are all-but-dead, and how the first generation of mobile phones was largely incompatible with modern standardised SIMs, frequencies, codecs, etc.

    I don't know what we

  • If life arises at all, it stands to reason that evolution would take hold and life would either adapt to the environment or adapt the environment to suit it.
  • Even these researchers don't understand the concept of time on a galactic scale. We've been around for a mere fraction of a second in terms of time scale. We haven't been around long enough for aliens to find us, or us to find them. It's why endeavors like SETI are, well, a waste of time.

    • The galactic scale actually helps the pro-alien viewpoint. There are so many billions of planets in the galaxy that we would expect them to spawn life. Many systems in our galaxy are far older than Earth [wikipedia.org]. By the time the Earth was formed, the linked solar system had already had a chance to evolve from accretion disk->Kardashians.

      And yet the galactic scale is no impediment to colonization. Assuming a 0.0025*c travel speed, it would take only 50 million years to colonize the galaxy [sentientdevelopments.com]. That's nothing in

  • "Researchers make wild ass fucking guess" because that's pretty much all it is when you have a sample size of one.

    In this case I'd assert that the person sitting next to you on the bus has nearly the same chance of being right, so clothing their opinion in the false-authority of calling them researchers is rather misleading.

  • Could ants detect signs of human civilization from their ant hill in the forest? Probably not, but this doesn't change the fact that human civilization exists, and side from occasional lawn extermination are largely unconcerned with ants.

    We are not contacted because our civilization is likely not at all unique and not at all interesting to entities capable of contacting us.
  • This sounds an awful lot like the discussion surrounding habitable planets 25 years ago. There really wasn't enough to raise the discourse above idle speculation because we were dealing with a sample of one (the solar system). The situation wasn't much better shortly after the discovery of exoplanets since the sample was incredibly biased.

    The situation for planetary atmospheres is similar today. We have an incredibly small sample of planets where we have studied the atmosphere in any detail (again, the s

  • ...it rarely evolves quickly enough to regulate greenhouse gases...

    If it isn't greater than one, your blowing smoke out your ass.

  • Doesn't anyone else remember Lovelock and the Gaia hypothesis? I think his books on Gaia were very popular back in the late 1980's
  • For live to have a chance, the planet has to have a large body which shields from periodic life-wiping asteroids hitting it. Every crater on the moon was caused by something hitting it which would wipe life on earth if the moon's gravitation didn't pull it in. Because the moon is far enough from earth and rotates quickly around it, it's able to attract most of the asteroids with a stronger gravitational pull than the earth's pull.
  • by SkyLeach ( 188871 ) on Wednesday June 08, 2016 @10:07AM (#52274363) Homepage

    Consider this: particle physics shows us that entangled observation (not to be confused with human or intelligent observation) ties past and future events together into a causative vector of influence.

    Extrapolating from this using entangled observation similar to Einstein-Rosen bridges between quantum events suggests (mathematically) that there is a correlation between frames of references in real-space once a chain of events is initiated.

    This would have the effect of linking independent causative frames such that the 'arrow of time' would diverge, probabilistically, between relative frames.

    Or, attempting to explain this analogically:

    The light from a distant star contains a tremendous amount of observable information about a star, and a limited amount of information about exoplanets (Doppler shift, chronographic direct imaging, etc...). As technology advances, however, it should be possible to tease out (observe) direct evidence of extrasolar life from this meager data due changes over time to how life changes a planetary atmosphere (specific to biome, but similar divergence vectors).

    Depending on how one interprets causative entangled observation, this could actually have a strong anthropic effect on life. Evidence that alien life, intelligent or not, exists on an exoplanet would strongly influence the actions of any intelligent species towards visiting and exploring the planet. This would be very close to a strong motivational influence towards any intelligent social network, yielding a high probability outcome of events.

    Depending on distance between planets and assuming that technological development is generally rapid, there becomes a high probability chance that any technological species would, inadvertently, directly affect the development (probably adversely) of all emergent evolutionary biomes within observational range.

    As a species matures, they would probably realize this at some point, and take one of two divergent vectors: Some level of apathy (no empathy, just settle habitable planets or destroy competition) or avoidance (let them develop, don't interfere). Extrapolating those two motivational vectors, it's likely that there are those that would visit for nefarious reasons, and likely that there are those that would seek to prevent that type of interference due to social morays based on the above principles.

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