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Fewer Than 10 ET Civilizations In Our Galaxy? 642

Posted by kdawson
from the black-rectangles dept.
Al writes "The Fermi Paradox focuses on the existence of advanced civilizations elsewhere in the galaxy. If these civilizations are out there — and many analyses suggest the galaxy should be teeming with life — why haven't we seen them? Carlos Cotta and Álvaro Morales from the University of Malaga in Spain investigate another angle by considering the speed at which a sufficiently advanced civilization could colonize the galaxy. Various analyses suggest that using spacecraft that travel at a tenth of the speed of light, the colonization wavefront could take some 50 million years to sweep the galaxy. Others have calculated that it may be closer to 13 billion years, which may explain ET's absence. Cotta and Morales study how automated probes sent ahead of the colonization could explore the galaxy. If these probes left evidence of a visit that lasts for 100 million years, then there can be no more than about 10 civilizations out there."
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Fewer Than 10 ET Civilizations In Our Galaxy?

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  • by eldavojohn (898314) * <eldavojohn.gmail@com> on Friday July 31, 2009 @10:18AM (#28895767) Journal

    Fewer Than 10 ET Civilizations In Our Galaxy?

    All this is assuming that we would know immediately if there were a 50-100 million year old alien probe in our solar system's backyard. Stack that on top of all the non-empirical data based percentages that go into the Fermi paradox and ...

    *puts on Twilight Zone music*

    Human beings are the alien probe!

    And man, we had better start compiling that report that's due when Quetzalcoatl/Jesus/Osiris/Thoth/Viracocha get back here. He's gonna be pissed when he sees that we just threw a huge party and trashed the place instead of assessing the resources!

    • Re: (Score:3, Insightful)

      by Ihlosi (895663)
      All this is assuming that we would know immediately if there were a 50-100 million year old alien probe in our solar system's backyard.

      Yes. There could be half a bajillion alien probes in the Kuiper belt, transmitting the latest antics of the Earthlings right to GalaxyTV, and we'd have no idea.

      • Re: (Score:3, Funny)

        by lorenlal (164133)

        I at least hope they're getting a good laugh.

      • by Anonymous Coward on Friday July 31, 2009 @10:34AM (#28895971)

        Why doesn't Ross, the bigger of the 'Friends', simply just EAT the other two?! - Omicron Persei 8

      • by bazorg (911295) on Friday July 31, 2009 @10:54AM (#28896257) Homepage
        So you are saying that our whole freaking planet is a reality show? agh!
      • by eldavojohn (898314) * <eldavojohn.gmail@com> on Friday July 31, 2009 @10:55AM (#28896269) Journal

        All this is assuming that we would know immediately if there were a 50-100 million year old alien probe in our solar system's backyard.

        Yes. There could be half a bajillion alien probes in the Kuiper belt, transmitting the latest antics of the Earthlings right to GalaxyTV, and we'd have no idea.

        I disagree. I shall propose what will be known as The eldavojohn Paradox which states that: If extraterrestrial life were watching our TV, surely Fox and the WB would have been attacked by now ... or at least a very harshly worded intergalactic message would have been delivered to the Fox executives about their nonsensical canceling of shows like Firefly and Futurama while promoting unadulterated drivel.

        You see, my assertion that extraterrestrials would enjoy the same television as I is just as utterly inept as assuming that their primary goal is establishing contact with other extraterrestrials. Who knows? Maybe they're too busy jumping between parallel universes to waste time talking to the Corky from Life Goes On of the Milky Way Galaxy? (that being us)

        Maybe they showed up and watched World War I and II and said, "Wow, that is some heavy shit. We'll ... we'll just come back later when you're not busy, ok?"

        Isn't the Maybe Game fun? It's like I'm a sci-fi writer with me as my own audience.

        • by thedonger (1317951) on Friday July 31, 2009 @11:31AM (#28896827)
          I propose thedonger Paradox:

          If there exists another race like earth-based humans, it proves our evolution is completely random because no intelligent, higher being would make us on purpose twice. On the other hand, if we are here our of sheer randomness then it is most probable we are, in fact, alone.
          • by loafula (1080631) on Friday July 31, 2009 @01:18PM (#28898419)
            I know you were joking here, but evolution only seems random from the outside looking in. In any given environment, life will evolve to take advantage of the available natural resources in the most efficient manner possible. Granted, the environment differs greatly from planet to planet, but I think we can agree that any planet hosting life as we know it will have some remarkable similarities to earth. Life will evolve in the best way to take advantage of that environment- two eyes to see in 3D, bipedal for mobility, upper limbs to manipulate things physically, brains to control it all, a mouth at the top and an ass at the bottom because gravity only knows down, some sense of smell to detect fuel(food), ears (or something similar) to detect predators, and some form of genitalia to reproduce.
            I often wonder if we are Earth's end-of-the-line inhabitant. Animals evolve to adapt to their environments. Us humans adapt the environment to suit us. Have we stopped evolving? It's a dangerous situation if we have, because then we become a non-changing environment for all the creepy-crawlies we are host to. Bacteria will rule the world in 100 million years! /rant
            • by thedonger (1317951) on Friday July 31, 2009 @01:39PM (#28898743)

              I meant random in the sense that a higher being wasn't planning our existence.

              Evolution is so slow I doubt we have the patience or longevity to observe it. In addition to "changing out environment to suit us," we also seek to prevent change from happening to our environment. I'm sure there are millions of people out there who would go to great lengths to ensure the survival of all extant species. Ironically, their logic is that man is changing things and endangering those species, yet not allowing them to become extinct is at odds with our changes. Of course, they'll argue that our changes are not natural, which is impossible. We occurred naturally, therefore whatever we do is part of nature, for better or worse.

              Perhaps we have reached a dead end for physical evolution, and given no other changes we'll outgrow this planet long before we figure out how and where to move off of it. But I suspect social evolution will intervene before that happens. Logan's Run, Soylent Green, 1984, Brave New World...Pick your future.

              In closing, I leave you with the words of the great prophets Fishbone: "Give a monkey a brain and he'll swear he's the center of the universe."

        • Maybe Firefly was too close to the truth...

          "[Shut down Firefly or we wipe out the planet.]"

          "[What? It's a good show, and the ratings are...]"

          "[NOW!]"

          Joss Whedon doomed us all with Serenity.

    • You know how we all get really mad at meteorologists and economists because they routinely get wrong the thing they predict with high certainty?

      I have the same feelings about astronomers.
    • by jgostling (1480343) on Friday July 31, 2009 @10:59AM (#28896323)
      We've trashed nothing. The whole point of sending us here is the development of global warming technology so they can actually inhabit the planet when they get here. We're not probes. We're just an alien-forming device.

      Cheers!
    • by r_jensen11 (598210) on Friday July 31, 2009 @11:10AM (#28896515)

      Human beings are the alien probe!

      Oh no! I don't want to be shoved up anything's ass!

  • What if... (Score:3, Interesting)

    by Anonymous Coward on Friday July 31, 2009 @10:18AM (#28895769)

    Sumary of the article: we pull numbers out of thin air and imagine stuff in consequence. I did a lot of that kind of "what if" as a kid with friends.

    • Give it time... (Score:5, Informative)

      by Dare nMc (468959) on Friday July 31, 2009 @10:39AM (#28896049)

      A good summary. Especially since they assume because we sent out a "identifier" once, that it is logical that all other civ's would continuously do that, just in case things change, and some youngsters show up. Instead of 1) send probes, get the info you want (or trash your orbit with satellites and crap so you can't lunch anything else) and give up, staying in your own solar system.

      Not to mention we only see stuff at the speed of light, if they only send stuff at 1/10 the speed of light. Anyone over a thousand light years away hasn't even seen any signs of life in our galaxy yet, let alone had a chance to respond in a manner that we will then be able to see for a few thousand more light years.

  • Cotta and Morales study how automated probes sent ahead of the colonization could explore the galaxy. If these probes left evidence of a visit that lasts for 100 million years, then there can be no more than about 10 civilizations out there

    Maybe there are more, but the rest are afraid of running into an advanced civilization who'll treat them as cattle

  • Why (Score:3, Interesting)

    by courteaudotbiz (1191083) on Friday July 31, 2009 @10:19AM (#28895793) Homepage
    I wonder why should one consider a colonisation of the whole Galaxy? Isn't it a too damn big territory to defend - explore - colonize? Without talking about the astronomical (ha ha) amount of human (E.T.) resources it would take to launch such an enterprise!
    • Re: (Score:3, Insightful)

      by Ihlosi (895663)

      I wonder why should one consider a colonisation of the whole Galaxy?

      Because someone else might have the same idea, and you need to beat them to it.

      Isn't it a too damn big territory to defend - explore - colonize?

      Well, if you manage to colonize the whole galaxy, you probably don't have to worry about defending it from external threats for quite a while.

      Without talking about the astronomical (ha ha) amount of human (E.T.) resources it would take to launch such an enterprise!

      Yes, it takes quite a bit of re

      • Re:Why (Score:5, Insightful)

        by SatanicPuppy (611928) * <Satanicpuppy@ g m a i l . c om> on Friday July 31, 2009 @11:13AM (#28896559) Journal

        "Well, if you manage to colonize the whole galaxy, you probably don't have to worry about defending it from external threats for quite a while."

        Okay, that's the funniest thing I've ever heard.

        Q: What's the biggest threat humanity has ever faced?
        A: Itself.

        Creating thousands of splinter civilizations with no emotional investment in the species homeworld is a recipe for galactic war if I've ever heard one.

        • Re: (Score:3, Insightful)

          by stwrtpj (518864)

          Creating thousands of splinter civilizations with no emotional investment in the species homeworld is a recipe for galactic war if I've ever heard one.

          What would be the point?

          Consider two "rival" worlds separated by a modest distance of 50 light years. Now assume that the top speed that ships can go remains 1/10 light speed as mentioned in the article. That's 500 years for your fleet to get to the other world. The time dilation at that speed would be small enough to be insignificant. Multi-generational warships anyone?

          So let's instead consider that we push the speed envelope. We're still limited in how fast we could go. Say we push it to 80% or maybe 90%

    • by bjourne (1034822)
      They assume that alien civilizations would grow exponentially like humanity. To maintain exponential growth the civilization would inevitably have to colonize other planets, other solar systems and even other galaxies. So if it only takes 50 million years to colonize the whole Milky Way then there can't be that many other intelligent life forms in the galaxy because we would have seen evidence of them.
      • Re: (Score:3, Insightful)

        by maxume (22995)

        You need to throw in a bunch of hand waving about statistics.

        It is at least possible that we are the first, most advanced civilization, out of some huge number in this vicinity (even if it is extremely unlikely...).

      • Mind the gap! (Score:5, Insightful)

        by rlseaman (1420667) on Friday July 31, 2009 @11:38AM (#28896921)

        bjourne points out: "They assume that alien civilizations would grow exponentially like humanity. To maintain exponential growth the civilization would inevitably have to colonize other planets, other solar systems and even other galaxies."

        What they really assume is that the laws of physics apply broadly across the cosmos. Darwin and Malthus do the rest.

        The real question is how hard it is to jump the gap from one world to the next. Science fiction authors assume this is not only possible but relatively easy, because otherwise they would have no story to write. Travel (of the few) within the solar system seems plausible. Travel (of the many) to neighboring stars is far beyond daunting.

        Consider Malthusian growth: Our population today is 6.602 billion souls. The current growth rate is 1.167% per annum. (Numbers are a couple of years old - it doesn't change the result.) Do the math.

        Today there were 210,000 more souls and 6000 tons more human flesh pressing inward on Mother Earth than yesterday. Tomorrow there will be 210,000 more. The day after - another 210,000. In six months that will be 211,000 per day - in a year, 212,000 per day, and so forth and so on. Less than a year from now there will be another 1.8 million tons of human flesh literally shouldering other species into extinction. That's not 1.8 million tons total - that's just the additional growth of skin and hair and sinew and good red meat locked up in your mama's Soylent Green recipe.

        For space travel to matter in the solution of this problem, we have to build a fleet of ships capable of offloading 210,000 people - a new space fleet every day, year after year - forever. A space shuttle carries a crew of seven - so we need 30,000 space shuttles a day. (Of course, that only gets you to low Earth orbit.) Each year we would have to move at least that 1.8 million tons of human cold cuts - that's the equivalent of 18 Nimitz class aircraft carriers - to some other distant, unwelcoming world.

        And then, of course, you've just shifted the horizon of the always looming catastrophe to a collection of planets rather than a single planet. Since this is a doubling issue, colonizing another planet - say, a terraformed Venus - just buys you an additional 60 years.

        • Re:Mind the gap! (Score:5, Interesting)

          by Anonymous Coward on Friday July 31, 2009 @01:20PM (#28898465)

          For space travel to matter in the solution of this problem, we have to build a fleet of ships capable of offloading 210,000 people - a new space fleet every day, year after year - forever.

          No we don't.

          We need robots, breeding tanks, freeze-dried embryos. Put a few thousand of 'em (along with DNA samples of a few thousand other humans) on a spaceship, and let the ship take care of the rest.

          The goal isn't to offload Earth's population at some linear rate.

          The goal is to spawn self-replicating colonies. If the ship travels at 10% of the speed of light (500 years to find a habitable planet within 50 light-years), but the ship can be made cheaply enough (suppose by the year 2200 we can do it for the GDP equivalent of an aircraft carrier and its support fleet), you just fire off a ship in a random direction every 10 years.

          The ship finds a suitable world, sets up shop, and the colonists spend the next 1500 years bootstrapping themselves from a Serenity-like Wild West settlements into million-person planetary civilizations capable of building their own seedships. Lather, rinse, repeat.

          Some colonies fail. Big deal. Sometimes you'll spread at 0.01c (500 years travel time, 4500 years of playing Sid Meier's Alpha Centauri). Sometimes you'll get lucky - (A ship that lasts for 4500 years and travels 450 light-years - and the lucky colonists reboot after only 1000 turns of gameplay :). Net effect is a wave of colonization spreading out at around 2-3% of c.

          The colonies are largely independent of each other; it's unlikely that they're all going to annihilate each other, or simultaneously annihilate themselves. The galaxy's 100,000 light-years wide, or about 300,000 light-years in circumference. The whole thing should be colonized within 10 million years. At less than half a percent of c, we're still talking about a hundred million years.

          That's an eyeblink, astronomically speaking. If it was going to have happened, it should already have happened. The universe has been around for 13.6 billion years. Life's been feasible for around 10 billion of those years, after the first wave of hydrogen/helium stars went supernova and gave the universe enough heavy elements to form planets and to do interesting chemistry. Our little rock has been around for around 4.5 billion years, and inhabited for 3.6 billion years of that time. It's hardly a stretch to think that something else started 0.1 billion years ahead of us. (or got started later, but skipped the billion-odd years of time that our biosphere spent dicking around with unicellular life in the precambrian era.)

          We're talking about 0.1 billion years to colonize the galaxy. Trivial for an advanced technological civilization. Assuming we're not the first, it should have happened by now. The fact that it hasn't happened is an indication that we're the first. (And as a corollary, that however common life may be in the universe, intelligent life must be mind-bogglingly, astonishingly rare. We've only been sentient for a million years, and smelting metal for a few thousand. An eyeblink of an eyeblink of an eyeblink.)

    • Re:Why (Score:5, Insightful)

      by fastest fascist (1086001) on Friday July 31, 2009 @11:16AM (#28896615)
      You can't really think of colonizing a galaxy in the way you might think of colonizing a new continent. The distances alone would make sure whatever reaches the far end of the galaxy would be a completely different species than the originator of the "colonization". Barring faster-than-light travel or some kind of extreme (from our point of view) psychology and genetics, I see no way a civilization spanning an entire galaxy could exist. If we colonized Mars now, it wouldn't be very long before they started to go their own way. Hell, the Americas were lost to the parent countries in a few centuries, and that's on the same planet.

      It just doesn't make much sense to take an expansionist view of space travel, unless maybe your species is very, very patient and stable. Any colonists you send far out, you will never have meaningful contact with again. At that point you might wonder what the point of "conquering" new systems is, in terms of nationalist-type expansionism.
      • Re:Why (Score:4, Insightful)

        by fastest fascist (1086001) on Friday July 31, 2009 @11:28AM (#28896775)
        Thinking about this this takes me to some kind of conclusion:

        Most civilizations would not expand very quickly at all, probably not much faster than they absolutely have to. Granted, you might imagine a very adventurous species that would send ark ships thousands of light years away just for the hell of it, but for the most part that seems unlikely, perhaps used as a last chance for survival. If any faraway colony is, in essence, as good as a different civilization, it makes little sense to send ships out very far. Moving out of a solar system would be a rare incident, mostly only taken up when the survival of the species is threatened. Just as you can't currently think of colonizing other planets as a solution for overpopulation on the earth - you just can't lift enough people off the planet for it to make a difference - you can't with any reasonably conceivable technology think of colonizing new solar systems as a solution for lack of resources or living space. You can send colonists out, but that's the last you'll see of them, and any problems you have in your own system, you will need to deal with there.
      • Re: (Score:3, Insightful)

        by Nimey (114278)

        Depends on how long it takes a Martian colony to become self-sufficient. Stuff can grow pretty well in the Americas, and it's not overly hard to extract natural resources. The same cannot be said of Mars, with its lack of atmosphere and magnetic field.

    • One of the reasons why we might not see the galaxy as teeming with life is beacuse all the life out there might not be capable of generating advanced technology. One of the assumptions in the equations is that all live will evolve to the point of sentience and begin building transistors. Why would this be the case?

      The dinosuars were doing pretty well as the dominant species for 100 million years without advanced technology, and if it were not for the KT event, they might have been the dominant species fo
  • by hort_wort (1401963) on Friday July 31, 2009 @10:21AM (#28895809)
    We've known there to be at most 10 civilizations ever since Master of Orion. A typical scenario is more like 6 though.
    • by u38cg (607297) <calum@callingthetune.co.uk> on Friday July 31, 2009 @10:36AM (#28895997) Homepage
      Personally, I'm still waiting for evidence there is *one* civilisation in this galaxy.
      • Re: (Score:3, Interesting)

        by b4upoo (166390)

        The logic of the story is faulty. To assume that capable civilizations would desire space travel is foolish in itself. Next if we do use the assumption that advanced critters would want to explore there is a second problem in assuming that they would not be unusually covert in those explorations. The next huge assumption is that craft or devices sent out to explore would be recognizable as such by humans.
        My own perfectly irrational assumptions include

      • Re: (Score:3, Funny)

        by euxneks (516538)

        Personally, I'm still waiting for evidence there is *one* civilisation in this galaxy.

        OH SNAP! You certainly told humanity! On a post on Slashdot no less!

    • Re: (Score:3, Funny)

      Funny, that's the first thing I thought, too. I hope the friggin' Meklars aren't playing.

  • Nonsense... (Score:2, Funny)

    by Vectronic (1221470)

    We should start bumping into Vulcans in about 54 years... Zefram Cochrane should be born pretty soon... then we'll know.

  • Nice point in general, but worthless without estimating the chances of finding these probes. A 100 million year old probe would not necessarily be easy to find even if it wants to be found and landed on earth.
    • ... that these probes already have and are seen by old ladies and drunks in the Arizona desert all the time!

    • Re: (Score:3, Interesting)

      by craagz (965952)
      It is possible that the probes lying at the bottom of the ocean were not designed to get wet because the host planet does not have water at all. Now these probes might be short circuited or something of that kind.
      • by Bakkster (1529253) <Bakkster@man.gmail@com> on Friday July 31, 2009 @12:25PM (#28897543)

        It is possible that the probes lying at the bottom of the ocean were not designed to get wet because the host planet does not have water at all. Now these probes might be short circuited or something of that kind.

        Expanding on this, what if they were looking for a planet like Mars or (harder to detect) Venus? Maybe the probe arived billions of years ago and saw three planets in adjacent orbits with water. Who's to say it would have picked the correct planet?

        As for detection, a single object sitting under the dense atmosphere of Venus for 100 million years doesn't exactly pop out at us.

  • by Dotren (1449427) on Friday July 31, 2009 @10:25AM (#28895855)

    I remember reading an interesting book called "The Science of Star Wars" that discussed the real life issues with the technology and situations in the original trilogy. This covered everything from the theoretical sciences behind the technologies like lightsabers, blasters, and lightspeed to the possibilities of existence of other life out there. I haven't read this book in a very long time and I don't have access to it at the moment, but I seem to remember it indicating that the odds of finding another planet with water, breathable air, and the exact distance from a sun necessary to help life flourish were so extremely low as to be laughable.

    I remember thinking even then how short-sighted that was and how arrogant it seemed.

    I realize these things are supposed to be scientific so they use only what they know to be fact, however, I think when dealing with complete unknowns such as the type of life out there or what their technology level may be at, you have to start thinking outside the box and be a bit more imaganitive.

    Who is to say, for example, what form other life will take? Would we even recognize it as life if we were standing right next to it? What about their technology? Who is to say that they haven't gotten past the lightspeed issues with relativity and energy required? Perhaps they have stealth technologies... would we even be able to detect them? Just because we don't know how to do it now, and just because our current science says it probably isn't possible, doesn't mean it can't be done.

    • by Ihlosi (895663) on Friday July 31, 2009 @10:29AM (#28895893)
      Would we even recognize it as life if we were standing right next to it?

      We pretty much know what rocks and ice look like. If the aliens aren't spectacularly good at masquerading as rock and ice, we'll recognize them.

      • Re: (Score:3, Insightful)

        by Artifakt (700173)

        I don't remember the novel it came from, but one SF writer had a bunch of human explorers run across pretty, slowly shifting, crystaline patterns floating as thin films on the surfaces of otherwise sterile oceans in a chemically exotic environment. Human initial response was pretty much limited to 'Ooooh shiny!" After weeks of scanning the whole planet and crunching numbers, one of the ship's scientists announces there is a sophisticated civilization with billions of participants encoded in each crystal mat

    • Re: (Score:3, Interesting)

      by geekoid (135745)

      Not laughable.

      there are over 70 sextillion stars. If the chance are 1 in a trillion we would ahve a galaxy teaming with intelligent life; however, That's over the period of 13 billion years.
      All evidence point to species becmoing ectinct sooner or later. so what are the odds of an intellegent species surviving to a point where they can send out probes?
      Even if a civilization created a probe that is trying to be fouind, it would still be very, very, very hard to detect, assuming it gets close enough to be dete

  • by ground.zero.612 (1563557) on Friday July 31, 2009 @10:29AM (#28895895)

    That's a great line from the lyrics of a Clutch song, and it's forced me to ask the question: "What would life be like today, if the moment we invented radio/television we started receiving 60yo broadcast transmissions from another planet?"

  • by midifarm (666278) on Friday July 31, 2009 @10:30AM (#28895913)
    This assumes that said ET's operate only in the 3D realm. What about wormholes, space folding and other theoretical methods that our limited understanding of physics doesn't allow us to see? Quit being such a downer. If Tesla was still alive I'm sure we'd have commerce with these ET's. Cheers...
  • by acehole (174372)

    So when did this mysterious 50 million years mark start? yesterday? 10 million years ago? 49? 65 million years ago?

  • Greed Effect (Score:2, Interesting)

    by Weeksauce (1410753)
    Why would thsee ET like civilizations would be any different in their evolutionary development than humans? If this is the case, than many intelligent species will most likely follow the path that we seem to be on. With varying religious factions/greed/war/and depletion of natural resources reaching a point where they kill themselves.

    Maybe there was a civiliation considerably more advanced than us, but whose to say they didn't destroy themselves by electing leaders who entered into wars over natural res
    • Or, perhaps created their own doomsday scenario. The nature of technology is that in order to do most anything worthwhile, you have to create self feeding processes. For man / life, the first one was reproduction. We've got that down pat; there's more than 8 billion of us. Then comes fire. This was the first technology that could really escape our control in a way to be immediately harmful. Now, we have nuclear reactors, bio-engineering, and potentially micro-black holes. And we're working on nanites
    • Re: (Score:3, Informative)

      by Utini420 (444935)

      You're thinking of the Drake equation:

      N = R* x Fp x Ne x Fl x Fe x Fi x Fc x L

      http://en.wikipedia.org/wiki/Drake_equation

      Without giving a lengthy description, at the beginning of the project that would grow into SETI, they asked more or less the same questions and decided that it really came down to, "What are the odds that after a given species invents radio, they invent nukes and destroy themselves?" The equation is intended to predict the number of advanced civilizations in the galaxy at any given time,

    • FYI... (Score:3, Informative)

      by denzacar (181829)

      We still haven't killed ourselves.

  • Probes (Score:5, Insightful)

    by UncleWilly (1128141) * <UncleWilly07&gmail,com> on Friday July 31, 2009 @10:34AM (#28895973)

    I am curious as to what evidence these alien probes would leave if they don't land and stay on a planet. If they just fly around, collect data and phone it home we would never see them.

    Even landing, unless they landed on Earth, our Moon or Mars, how would we see it? I'm not even certain our own probes can spot our own rovers on Mars. Lets say they did put a probe down on earth (like our mars rover) say recently, like 100,000,000 years ago; it could easily be hidden under a kilometer of dirt and rocks and never be found. Time, like space, is vast.

    • by Ihlosi (895663)
      I'm not even certain our own probes can spot our own rovers on Mars.

      Yes they can. At least some of those that are in Mars orbit. There are some nice pictures of the landers, the parachutes, etc.

  • Assumptions (Score:3, Insightful)

    by I.M.O.G. (811163) <spamisyummy@gmail.com> on Friday July 31, 2009 @10:42AM (#28896085) Homepage

    This assumes a sufficiently advanced civilization could survive itself for a sufficient span. Taking the only advanced civilizations we know into account - the human race - I don't see how its realistic to expect survival into the "millions of years" range.

    I'd put forth that any civilization advanced enough to develop such technological advances, would kill itself long before such technology develops. Our current modus operandi is not sustainable millions of years out, and using the human race as a basis, I think it laughable to consider the possibility of survival for millions of years. The oldest human remains are what, about 160,000 years old? Might we be getting ahead of ourselves speaking about intelligent life colonizing the galaxy?

    Crocodiles on the other hand - those bastards are believed to be around 200 million years old. They've exhibited a much better understanding for what it takes to survive long term (of course we're doing a pretty good job of killing them too - you can say people are bad at somethings, but everyone has to admit we're really good at killing other stuff). If crocs could somehow work space travel into their lifestyle, this could lead to something...

    • Re: (Score:3, Funny)

      by Chris Burke (6130)

      you can say people are bad at somethings, but everyone has to admit we're really good at killing other stuff

      Or we'll kill them.

  • by logicnazi (169418) <logicnazi@gmail. ... minus herbivore> on Friday July 31, 2009 @10:43AM (#28896097) Homepage
    It's always seemed to me that the major hole in the Fermi paradox is the assumption that technologically advanced alien civilizations would be emitting signals we would recognize.

    I mean it's kinda hubristic to assume they want to talk to us. After all we may study chimps but we don't go out of our way to show up in the middle of nowhere to say hello. That leaves the question of why we don't detect communication leakage, e.g., radio signals they use for communication. However, not only is it not obvious that they would use radio to communicate, or that we could recognize such signals, but it's not even obvious they would bother to colonize the galaxy or communicate between planets.

    For example suppose that sufficiently advanced civilizations transform themselves into some form of 'computational' life. Such a civilization couldn't care less about planents or minerals. What would matter to them is processing power per unit volume. It would therefore make sense for such civilizations to seek out the regions with the highest energy density that would allow them to access the most processing power. Rather than racing around the galaxy in starships and living at the same crawlingly slow pace we do such civilizations might exist entirely in the high energy regions in neutron stars or around black holes. So why would we expect to meet them. Hell, even if they care about meeting aliens too the aliens they care about are probably the ones who already inhabit similar regions.

    Even if we think it's reasonable to assume aliens are sending messages all over the galaxy the more efficiently such messages are encoded the harder it will be for us to identify them. The closer such transmissions approach the Shannon limit for the communications channel the harder they would be to distinguish from random noise (and we don't know enough to rule out a natural source). Also the more effective use they made of their communications equipment the less stray signal that would wash the earth, even if it was encoded in radio instead of neutrinos or something weird (some papers have suggested neutrinos would be a better long range communication method).

    The point is that even if we take for granted that there a fucktons of advanced alien civilizations around it just doesn't follow that we should be able to detect them.
    • Re: (Score:3, Insightful)

      by tzhuge (1031302)
      I would say the assumption isn't so much based on hubris as on practical considerations. We only really know our civilization, so we can only make these kinds of conjectures based on what an advanced version of our own civilization would be like (we would so trash the place with probes). If we don't make those assumptions, then there really is no starting point to get very far on this kind of 'what-ifs'. Maybe the planets are sentient...
    • Re: (Score:3, Insightful)

      by Swizec (978239)

      However, not only is it not obvious that they would use radio to communicate, or that we could recognize such signals, but it's not even obvious they would bother to colonize the galaxy or communicate between planets.

      Exactly, why would you want to communicate between planets when in a few thousand years after having populated one everybody you left there will forget they're still the aliens? Even their technology would probably start diverging from what you left them with and eventually they'd become a group of organisms looking into the sky to find aliens and wondering why there aren't any ...

      ... maybe that's why we're so adamant about finding them. Deep down somewhere we know we're aliens and would like to go home no

    • It's always seemed to me that the major hole in the Fermi paradox is the assumption that technologically advanced alien civilizations would be emitting signals we would recognize.

      In common with authors the wrote the cited paper, and most commentators on the subject (and virtually everyone who claims to have a "resolution" for the Fermi Paradox), the above comment fails to understand the essence of the Fermi Paradox -- what actually makes it profoundly paradoxical.

      The Fermi Paradox does not assume that "technologically advanced alien civilizations" (in general) "would be emitting signals we would recognize". The paradox lies in the fact that the Universe is a very big, and very old

  • by Ktistec Machine (159201) on Friday July 31, 2009 @10:44AM (#28896117)

    ...and we haven't been back since. Beyond the question of how long it would take a motivated civilization to expand throughout the galaxy, there's the question of "would they bother?". We don't seem to be bothering.

    • Re: (Score:3, Insightful)

      by interval1066 (668936)

      @Ktistec Machine: "We don't seem to be bothering."

      Chastising ourselves for our lack of will regarding space exploration is all well and good but the fact of the matter is that space exploration is no light matter. It currently requires a great amount of effort, will, economic consumption, and resolve.

      That the US was able to go to the moon during the cold war should not be taken lightly. Of course, the only reason we were able to do both things is that we were still coasting on our fortunes gained from WWII

    • by scorp1us (235526) on Friday July 31, 2009 @11:29AM (#28896799) Journal
      I think a better question is "could they bother" or the "Battlestar Galactica" problem. (Honorable mention to Trigun) Any craft, unless capable of near-luminal speeds will take a large amount of time and energy to get there. This craft will require maintenance over the duration, and after arriving at a a destination will be limited by the lack of industry at the destination. Meaning, once you get somewhere, all your technology goes away eventually, unless you transport a population large enough to build the most complex part on a ship (for us a microprocessor) You can cheat for a little while and take a small chip fab plant with you, but eventually that will need parts too. What you'll end up with ia a devolution of society. Given the problems the pilgrims had at Plymouth rock, (on the same planet) the survival of the group is far from assured. i.e. Jamestown and the the other colonies. Meanwhile your source civilization is capable of being wiped out by an asteroid or comet. Sure it may take 30 or 100 years to get the part delivered, but it to too long of delay. I think any civilization out there would focus on the much more down-to-earth effort of population and resource management. We should also be looking at populating the oceans, because given an asteroid impact, that is the safest place to be overall.
      • Re: (Score:3, Interesting)

        by schmiddy (599730)

        once you get somewhere, all your technology goes away eventually, unless you transport a population large enough to build the most complex part on a ship (for us a microprocessor)

        The only absolutely vital thing to transport is information (since it can't easily be reconstructed from scratch). And hard drives are small these days. There's absolutely no fundamental reason why the technology to build, say, a chip fab needs to take up a lot of room. It's certainly conceivable that you could send a few nanobots

      • Re: (Score:3, Insightful)

        by geekoid (135745)

        "all your technology goes away eventually, "

        Only if they are incredible stupid and short sighted.

        Since they have space flight, I will presume they are neither.

        You know when you get there you will need to build an infrastructer.
        So you takes some fundamental resource with you.
        For example, take what is needed to build a nuclear reactor*.
        Build it, now you have power. Then you mine to replenish resources and build.
        You don't go through all the technology phases again.

        *what ever technology you are using to power t

  • by gurps_npc (621217) on Friday July 31, 2009 @10:44AM (#28896121) Homepage
    1. Prime Directive like rule.

    2. War on. Radio silence.

    3. Wrong physics. Outside the bow-shock of a sun, radio works a lot different than we thought.

    4. Cheap FTL communication happens to be just around the corner.

    5. They are life, but not-as-we-know it and don't know about radio. Examples: Dark Matter, Live on a sun, live on a black whole. Note all three of these things are more common (on a mass basis) than planets.

    6. Powerful, rich, major religion/government objects to radio and shuns those that use it, trades freely with those that avoid it.

    7. Radio is deadly poison to one of the major alien species.

    8. Most races are born telepathic.

    9. Radio turns out to to cause global warming. (OK, this one is a bit silly.)

    10. Industrial processes moved off world act as a radio scrambler/jammer. Races still use radio within their world, but their signals are jammed by the intereference from say the cheap production of anti-matter scramble the signals.

    • by bashibazouk (582054) on Friday July 31, 2009 @11:05AM (#28896425) Journal

      To add to that:

      If you took a completely alien language, encrypted it. Compressed the hell out of it, then applied 10,000 to a million years of technological advancement to the sending of it, would we even be able to notice it from background noise? Even if radio was still used to send it?

    • by kalidasa (577403) on Friday July 31, 2009 @11:45AM (#28897035) Journal
      1 and 2 are both well known hypotheses. 3 is very unlikely, since we pick up radio emissions from natural sources all the time. 4 is very unlikely, but possible. 5 well known hypothesis 6 interesting! 7 very, very unlikely, given the natural sources we know about 8 what transmission medium does the telepathy use? Is it EM based? Is the range infinite so you don't have to use EM for long distance comm? 9 Yes, it's a bit silly. Radio isn't all that powerful. 10 Yeah, heard that one before once or twice, but not a well-known one. Good job! 11 well known hypothesis : all we can find at this point is beacons, and nobody is using them 12 well known hypothesis : optical works better, but of course is highly directional, and we're not on line of sight
    • Re: (Score:3, Insightful)

      by qwerty shrdlu (799408)
      11. Detecting radio signals at interstellar ranges is _hard_, unless the source is as powerfull as a star.
  • Calvin (Score:5, Insightful)

    by residieu (577863) on Friday July 31, 2009 @10:54AM (#28896251)
    "Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us."
    -Calvin
  • Orion's Arm (Score:3, Interesting)

    by Rashdot (845549) on Friday July 31, 2009 @11:01AM (#28896371)

    Visit Orion's Arm for an idea what populating the galaxy might be like.

    http://www.orionsarm.com/ [orionsarm.com]

  • by John Hasler (414242) on Friday July 31, 2009 @12:06PM (#28897335) Homepage

    Let alone evidence that would last a million years. A probe could have come through a thousand years ago, hung around taking pictures and measurements for a few years and moved on. We'd never know.

  • by wilder_card (774631) on Friday July 31, 2009 @12:17PM (#28897459)
    The only civilizations still surviving in our galaxy are extraordinarily powerful and consider humanity beneath notice. Which is a Good Thing, because when they notice you, it does not go well. Really, Miskatonic University is the only institution doing useful work in this area. Unfortunately they have trouble keeping research staff on.
  • We Are In Quarantine (Score:3, Interesting)

    by johnos (109351) on Friday July 31, 2009 @03:55PM (#28900973)
    Fermi's Paradox came up in a dream once. The explanation, according to the dream, is that Earth is in quarantine. The powers that be in the Galaxy put a communications blocking bubble around the solar system of all new technological civilizations for 10,000 or 15,000 years. The point of the exercise is that new civilizations are like teenagers, dangerous and unaware of their power to wreak havoc. This is especially true of newcomers that discover inter stellar travel while not yet having complete control over their atomics. So they just wall us off until we either 1) destroy ourselves, or 2) grow out of our galactic adolescence.

    The dream went on to explain why we see UFOs that don't communicate with us. They are outlaws breaking the quarantine. Humans, said the dream, have unique language abilities unknown elsewhere in the galaxy. A single human could write more and better code than teams of hundreds in the next-best software civilization. So the UFOs are from some of the shadier civilizations out there and they come to kidnap code slaves. They have to stay stealthy or they will get caught.

    This was a real dream I had about 10 years ago. And yes, I was asleep at the time. The story is obviously full of holes, it was only a dream after all, but intriguing.
  • techy (Score:3, Interesting)

    by Merovign (557032) on Friday July 31, 2009 @04:04PM (#28901153)

    I know I'm just being techy, but you can't actually STUDY something until you have at least one example of it.

    A lot of cosmological science and just about all exobiological science is completely made-up, maybe I'm just tired of "science news" that is 100% fictional.

    Frankly, we have nearly zero knowledge of life in the rest of the universe - it's okay to speculate, just call it speculation.

  • by blurker (1007141) on Friday July 31, 2009 @04:33PM (#28901711) Homepage
    Call it the blurker hypothesis. Think about it. The universe is maybe 14b years old. Our own planet is about 4b years old. For Earth to form, there had to be a giant dust cloud full of iron and other heavy elements, which can only have come from novae/supernovae. So at least one generation of stars had to form, burn out, explode, cool to ash, and then reform into new gravity wells to form this solar system. Since this one is about 4b years old, and can be expected to make it another 4b or so, then that leaves a tidy 10b years for a previous star cloud to seed our local region of space. Seems like just enough time. So we haven't seen other intelligent life yet because we are among the first ones to emerge from the ash...
  • 1: God-like* alien intelligence is all around us and they're enjoying the show --or completely disinterested.
    2: FTL or even near light speed travel is impossible and we're limited to contact with close neighbors.
    3: We're the first technological species in the neighborhood (maybe life and/or intelligence is just incredibly unlikely).

    -----
    *They would have tech perhaps millions of years ahead of us

  • is that the number of planets that can host life forms is so low in number, that some sort of Terraforming technology would have to be made to make the Mars and Venus type planets more like Earth.

    Right now we cannot even control the pollution on Earth that is making Earth less hospitable to current lifeforms.

    If there is more advanced life in the universe, they'd have to find a solution to their own pollution as well as invent Terraforming technology. If they don't, eventually they will go extinct.

    There is also a good chance that Earth is the most advanced life forms in our galaxy and if other life exists, it hasn't even invented radio devices yet so we can detect them, or they are too far away that radio waves from their planet has not reached Earth yet.

    There is also another possibility that maybe life on other planets skipped radio if they are advanced enough and use some other way to communicate that we cannot detect, or they use radio and use an encryption that makes it look like natural random signals to less advanced life forms.

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