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Space Science

New Study Shows Solar System Is Uncommon 290

Posted by kdawson
from the isn't-that-special dept.
Iddo Genuth writes "Research conducted by a team of North American scientists shows our solar system is special, contrary to the accepted theory that it is an average planetary system. Using computer simulations to follow the development of planets, it was shown that very specific conditions are needed for a proto-stellar disk to evolve into a solar system-like planetary system. The simulations show that in most cases either no planets are created, or planets are formed and then migrate towards the disk center and acquire highly elliptical orbits." The research was published in Science magazine; here's the paper on ArXiv (PDF).
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New Study Shows Solar System Is Uncommon

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  • Great! (Score:5, Funny)

    by vigmeister (1112659) on Tuesday September 02, 2008 @05:16AM (#24839983)

    Ever since mothers were allowed into academia, all their research has been telling us is that we are SPECIAL.

    Cheers!

    • Re:Great! (Score:5, Insightful)

      by tomtomtom777 (1148633) on Tuesday September 02, 2008 @05:20AM (#24840005) Homepage

      I wouldn't read it like that

      Space is still the big unknown. If this "shows' anything, it seems more probable that this 'shows' that the simulations aren't complete enough yet.

      If they would deduce this from actual statistical data, it would show something, but deducing this from simulation seems a a bit to trustful to the current state of science if you ask me

      • Re:Great! (Score:5, Insightful)

        by 4D6963 (933028) on Tuesday September 02, 2008 @05:38AM (#24840111)

        I agree. Basing conclusions off simulation models is risky, mainly considered how in the domain of planetary simulations, well established models get entirely questioned every once in a while.

        And at this point even actual statistical data is hard to use to conclude anything about our solar system, because of our limited observation capabilities, what we know has a heavy statistical bias.

        • Climate Science (Score:5, Insightful)

          by bencollier (1156337) on Tuesday September 02, 2008 @05:45AM (#24840143) Homepage
          I dislike pointing this out, but that's an interesting parallel with climate science. I remember hearing recently (on Slashdot?) that climate models primarily base their data on one or two sources that, if altered slightly, would throw the simulations pretty severely, one way *or* the other.
          • Re:Climate Science (Score:5, Informative)

            by asc99c (938635) on Tuesday September 02, 2008 @06:22AM (#24840335) Homepage

            It's an interesting parallel with anything where you base a conclusion off a simulation. But with climate science there are very significant differences.

            With our own planet we have reasonable records of how conditions changed in the past and the results of that. We've got extremely detailed recording of the current situation and the recent past. We've got firmly established science showing why those changes would cause those results. The world's climate is a little chaotic and the simulations match that state of affairs.

            When modelling planetary discs, we're nowhere near as sure of the physics. We can only get decent observations of our own solar system, and there isn't a disc of dust to observe. Even the best telescopes can barely see the discs of dust around stars. We could barely detect our own solar system around another star, let alone watch it form.

            • Re: (Score:3, Interesting)

              by peragrin (659227)

              Actually no we don't have a lot of reasonable data. We have a few hundred point sources from before 1920, and it slowly goes up from there. indeed according to climatologists this past summer should have been warmer than average, yet instead it was cooler. climatologists will need to be right more than 50% of the time if they want me to believe them. Heck just this past weekend the only thing they predicted correctly was the daily highs and lows. They were so far off the mark with wind, clouds and rain

              • Re:Climate Science (Score:5, Insightful)

                by Ihlosi (895663) on Tuesday September 02, 2008 @07:16AM (#24840611)
                climatologists will need to be right more than 50% of the time if they want me to believe them. Heck just this past weekend the only thing they predicted correctly was the daily highs and lows.

                And you'll need to stop confusing climatologists with meteorologists.

                • by sleeponthemic (1253494) on Tuesday September 02, 2008 @08:24AM (#24841095) Homepage

                  climatologists will need to be right more than 50% of the time if they want me to believe them. Heck just this past weekend the only thing they predicted correctly was the daily highs and lows.

                  And you'll need to stop confusing climatologists with meteorologists.

                  What does a meteor have to do with this weekends weather?

                  Leave science to the scientologists I say..

                  (They're the authentically named 'ologists for the job).

                • by sm62704 (957197)

                  And you'll need to stop confusing climatologists with meteorologists.

                  I'be always wondered, why do they call them meteorologists when they don't study meteors? Do they call people who study asteroids and comets "weatherologists"?

              • Re:Climate Science (Score:5, Informative)

                by vidarh (309115) <vidar@hokstad.com> on Tuesday September 02, 2008 @07:41AM (#24840775) Homepage Journal
                Climatologists are now working with reasonable proxy data for the last 1300 years, not just "a few hundred point sources". These proxies are things we can measure today but that reflect past temperatures, such as sediments, growth rate of coral etc.
                • Re: (Score:3, Interesting)

                  Growth rate of coral. Wow, talk about drinking the kool-aid. How does anyone know what else might have affected the growth rate of coral at the time? And "sediments"? I know this is difficult for people who want/need to believe in the latest fad, but you can't tell someone what the temperatures were without a measurement of said temperatures with an accurate temperature measurement device installed and calibrated to our modern specifications being used by people of whatever time period you are wondering

                  • Re:Climate Science (Score:5, Informative)

                    by asc99c (938635) on Tuesday September 02, 2008 @08:09AM (#24840963) Homepage

                    Growth rate of coral is one data point. You can also look at ice cores, tree rings, stalactites, isotope analysis of rocks. And sediments can refer to all kinds of interesting information, both organic and inorganic in nature.

                    You might be able to cast doubt on coral growth rings, but when everything is pointing in the same direction, you've got to pay attention to the most obvious reason for that.

                    • Re: (Score:3, Insightful)

                      Which will not give you anything resembling exact temperatures. Which you would actually need to plot "data" points.

                  • Re:Climate Science (Score:5, Informative)

                    by Ambitwistor (1041236) on Tuesday September 02, 2008 @08:31AM (#24841161)

                    How does anyone know what else might have affected the growth rate of coral at the time?

                    For one, they look at corals of the same species from around the world which grow in regions of different temperature, salinity, etc., and see how those factors are affect the coral's growth.

                    The other poster has a more complete answer to the broader question.

                    but you can't tell someone what the temperatures were without a measurement of said temperatures with an accurate temperature measurement device

                    That's manifestly false. Oxygen isotope proxies in ice cores are one of the prime examples of good paleothermometers, when they can be used; they depend on the rate at which heavier isotopes are transported in warmer or colder air, which is just physics. You don't need to worry about biological fractionation and such. Other proxies do good or fair jobs, depending on the type and the circumstances. Ocean proxies often do better than land proxies, since conditions are more stable. Almost all proxies are better at measuring temperature changes than absolute temperatures, though.

                    We have no reasonably accurate measurement of temperature before the existence of reasonably accurate measurement devices.

                    I'm sure you came to that conclusion from a thorough reading and analysis of the paleoproxy climate literature.

                  • Re: (Score:3, Informative)

                    by SETIGuy (33768)

                    It's like the Zero-population gain folks, with their Malthusian scenarios.

                    You do realize that population growth will have to hit zero at some point, don't you? It doesn't matter whether growth is exponential or linear. Positive growth for infinite time is not possible.

                    The question is only whether population growth goes to zero in a controlled manner, or goes very negative in an uncontrolled manner.

                    Do you remember people talking about high food prices earlier this year? Do you remember people talking about high old prices? There is no food crisis. There is no oil crisis

              • by Splab (574204)

                Sigh. Why does people still insist on thinking global "warming" means it gets warmer?

                No we have no conclusive fact that humans are the ones causing _climate change_ but the climate change is very real.

                Travel around Europe and all will tell you same, weather isn't as it used to be.

                It might be that we have no chance of changing the course - perhaps the sun is getting warmer and we can do squat about that - but what if taking the bike/public transport, turning off your equipment instead of standby did make a d

                • by rohan972 (880586)

                  Sigh. Why does people still insist on thinking global "warming" means it gets warmer?

                  It's because of the word "warming" I think. Some people are still clinging to the outdated notion that it means "to raise in temperature". I blame dictionaries.

                  Travel around Europe and all will tell you same, weather isn't as it used to be.

                  Just like language, it would seem. But you are right, England isn't wine producing country like it used to be, and Greenland hasn't yet regained the viable farming production it once had. Patience, Splab, all in good time.

          • by Candid88 (1292486)

            Whilst I see the comparison there are some major differences. We have climate records going back thousands of years and more (ice samples, tree rings, fossilized plant growth, crystal growth, geological formations etc.) and the ability to perform direct observation on the climate.

            Other solar systems however are an almost complete unknown. We have no past data to validate anything against and we have only recently started indirectly detecting the existance of extra-solar planets through very complex means.

            I

          • Re:Climate Science (Score:5, Interesting)

            by v1 (525388) on Tuesday September 02, 2008 @07:41AM (#24840781) Homepage Journal

            That sort of situation is commonly called "the butterfly effect". As the saying goes, a butterfly flapping its wings over a highway in australia could be the deciding factor as to the path of a hurricane in the gulf three weeks from now.

            While that's a little extreme, it's meant to illustrate the point of highly interactive systems that are "extremely sensitive to initial conditions". For example, a single microbe that hitchhiked on Spirit or Opportunity could lead to the terraforming of mars a millennia later.

            Weather has always been considered highly sensitive to initial conditions, meaning very subtle differences in the weather conditions today can have a profound effect on the weather a week later. The interesting thing about weather is that it doesn't take a millennia to change things miles away, it can do it in a couple hours.

          • I don't know what data sources you're talking about, but that doesn't appear to be the case for the climate models I'm familiar with. You need a pretty large change in radiative forcing to significantly alter the simulation output, at least on the large scales that such models are typically used for (global and continental multidecadal trends). Alternatively, you can monkey around with the feedbacks, which is why the models have climate sensitivities which range over maybe 2-4 degrees. But to get a feedb

        • Re: (Score:3, Informative)

          by Tom (822)

          I disagree. Simulation is a good method to check your basics and verify patterns. Like all things, it's a tool that you need to know how to use and what to use it for. Only in very well understood fields do simulations give you good numbers to work with. But even in poorly understood fields, then are a way to check your theories, by letting them "run" and see if the results coincide with the expectations and/or actual observations.

          So if, for example, you have a theory about how planets are formed, and put i

          • Re:Great! (Score:4, Interesting)

            by JasterBobaMereel (1102861) on Tuesday September 02, 2008 @08:05AM (#24840933)

            Number of Planetary systems we have completely explored - None! - We found a new (dwarf) planet Eris 2,500 kilometres in diameter and 27% more massive than Pluto in 2003

            All the other planetary systems we have found have massive sampling bias (we can only detect large planets, and easily detect close orbiting large planets)

            All of the systems like ours are undetectable or nearly undetectable at present

            It's a black swan problem - Until the 17th century a black swan was a metaphor for something that did not exist ... then Australia was discovered along with Cygnus atratus

        • Re: (Score:3, Insightful)

          by khakipuce (625944)
          It is always difficult (impossible?) to extrapolate from a single point. We don't know the shape of the curve or the direction to draw it in.

          Add to that a lot of speculation about planetary formation and who can have any degree of certainty about where our solar system sits in the scheme of things.

          We need to observe many more planetary systems before we have a clue.

      • Space may be unknown, but by commonly accepted theories the universe is also pretty damn big. Some people even throw around the word 'infinite' Regardless, even if space is some twisted doughnut shape, there are still a few hundred billion other galaxies out there that we can see just in the visible universe. This little fact, at least in my tiny world, equates to a rather large potential for similar types of solar system being out there.

        I concur with the parent poster. This makes us very much not special a

        • by Firethorn (177587)

          Just because we're a 'one in a million' or even 'one in a billion' doesn't mean that we're unique, especially as there are so many stars out there.

          Still, it does give us poor prosepects for colonizing other stars in the future. At least until we become independant of planets.

          Heck, that leads into my theory why Earth wasn't colonized by intelligent life in the past - travel times are so long that by the time an alien race can make the journey, they're purely space bound, other than their home system. They

      • If this "shows' anything, it seems more probable that this 'shows' that the simulations aren't complete enough yet.

        Of course. They did not even mention Great A'Tuin, so how could their model be complete?

      • Re: (Score:2, Insightful)

        by Dahlgil (631022)
        Hehe. Yes, if the computer models show something other than what we already know to be true (that we can't possibly be special...because you know what that would mean), then their models must be incomplete and reworked until such time as they agree with what we know to be true.
      • I wouldn't read into the article title so negatively "uncommon" when talking about stars is a pretty big number.

        Also if you read the linked PDF with the paper, the graph shows what kind of numbers they are talking about, about 6 out of 100 simulations resulted in solar system like configurations.

        M

    • Ever since mothers were allowed into academia, all their research has been telling us is that we are SPECIAL.

      You mean like this [slowdays.org]? Or...?

    • In Isaac Asimov's Foundation series, our solar system was special. In it, humans were the only sentient life forms in the galaxy. It had a "scientist" (who only did book research) discussing the "owigin question" of where humanity started ("...some say sol, oah Alpha Centuri...").

      In (IIRC, it's been a while since I read the books) Foundation's edge the story had Earth, where humanity started, a radioactive wasteland, and it was revealed that having two gas giants in the center orbits and our giant moon were

  • What is rare? (Score:5, Insightful)

    by kinabrew (1053930) on Tuesday September 02, 2008 @05:28AM (#24840047) Journal

    If even one thousandth of one percent of stars form solar systems similar to this one, that would still be quite significant.

    • Re: (Score:3, Funny)

      by RuBLed (995686)
      Maybe our solar system is a pre-BC (Before Creation) universe drop; nobody is farming those anymore...
    • by Neuropol (665537)
      exactly. And the general tone of this article seems to want to steer people from thinking just that, when in fact just the opposite, as you've stated is true. Planetary systems are not uncommon, maybe the ones that have the exact same properties and chemical energy structures as ours, but most certainly not entirely uncommon. That's absurd.
    • Re: (Score:3, Insightful)

      by antirelic (1030688)

      1/1000th of 0.01%

      I think that statistic is a bit hopeful. My current understanding of how the "earth" came to be a hospitable place, is due to a cosmic collision on such a scale that it changed the entire ecosystem of earth. The impact was so massive that it made the event that caused the dino's to be wiped out to look like a pin prick.

      I'm sure cosmic collisions of that size occur all the time (speaking astronomically), but what are the chances that "large objects" (earth sized), at the right distance from

      • You say tomatoe, I say tomatoe, you say unusual, I say inevitable.

        I hear God did it. That's what they're teaching the kids in school these days, right?

        Honestly, who gives a shit what these people have to say? They're so far removed from credibility, they may as well be quoting Nostradamus.

  • ok. (Score:2, Insightful)

    by thhamm (764787)
    but keep looking, please.
  • Under which model? (Score:5, Insightful)

    by Xiroth (917768) on Tuesday September 02, 2008 @05:33AM (#24840081)
    I have to ask: Under which solar formation model was this conclusion drawn? Because from what I understand, there are a number of competing theories, none of which have come anywhere near being conclusively proven. I actually studied under the creator of one of the models, Andrew Prentice [wikipedia.org], and was in a position to watch as the predictions of various hypotheses were proven true or false. We've got a long way to go in the field, from what I understand.
    • Anybody who has been following this stuff knows that it is a field in very active development. One problem for all models is that you need more than one actual example to test the model - which is one of the things that makes climate prediction so challenging.

      The article linked to also seems to have been written with Creationist bias, because it suggests our solar system is "unique". The authors don't claim that, and if they did it would be junk, not science.

    • by rasman1978 (1158339) on Tuesday September 02, 2008 @07:53AM (#24840853) Homepage
      You were an apprentice under A. Prentice?
    • by Kjella (173770)

      I have to ask: Under which solar formation model was this conclusion drawn?

      No idea, but I'm at least sure there's a selection bias on who gets headlines with models leading to spectacular conclusions == publicity and more research money. I really doubt this hunk of rock is really that special, yes we have a large gas giant in a distant orbit, yes we are in the right orbit, yes we have a magnetic field and yes we have a satellite, surely not many planets have that but... there's also a farking great universe out there. Maybe our closest neighbors aren't habitable, but if we could h

  • special. (Score:2, Insightful)

    by bronney (638318)

    The question isn't whether it is special, but HOW special. And TFS failed to even give a fake number to calm us data freaks down.

    • The question isn't whether it is special, but HOW special.

      Exactly. What's the probability of forming a "solar system like" planetary system ? 1:10? 1:1000? 1:1000000? 1:1000000000? The first two would still give us "lots" of hits inside our galaxy, while still being "uncommon".

      Dangit, get some more planet-finding telescopes out there, on the double! We need data to back up the hypothesis.

    • by dave420 (699308)
      8.5/10. Is that ok? :)
  • by Brain Damaged Bogan (1006835) on Tuesday September 02, 2008 @05:49AM (#24840171)
    ... then what chances do we have of finding a solar system populated entirely by hot large-perky-breasted nymphomaniac supermodels that love nerds?
  • by Layth (1090489) on Tuesday September 02, 2008 @05:51AM (#24840177)

    Just what are the odds that every alien encounter will be with bipeds that have vocal communication!

  • by Dan East (318230) on Tuesday September 02, 2008 @06:23AM (#24840347) Homepage Journal

    Solar Systems Like Ours Are Likely To Be Rare [slashdot.org]

    KentuckyFC writes
    "Astronomers have discovered some 250 planetary systems beyond our own, many of them with curious properties. In particular, our theories of planet formation are challenged by 'hot Jupiters,' gas giants that orbit close to their parent stars. Current thinking is that gas giants can only form far away from stars because gas and dust simply gets blown away from the inner regions. Now astronomers have used computer simulations of the way planetary systems form to understand what is going on (abstract [arxiv.org]). It looks as if gas giants often form a long way from stars and then migrate inwards. That has implications for us: a migrating gas giant sweeps away all in its path, including rocky planets in the habitable zone. And that means that solar systems like ours are likely to be rare [arxivblog.com]."

  • by Spit (23158) on Tuesday September 02, 2008 @06:38AM (#24840415)

    Modelling has indicated that the solar-system isn't as common as previously thought. Scientists estimate that only 2^2340987890 similar solar systems exist in the local group.

  • Special one (Score:5, Insightful)

    by Anonymous Coward on Tuesday September 02, 2008 @06:43AM (#24840431)

    Research conducted by a team of North American scientist shows our solar system is special

    ... therefore, God created this solar system specially for man, which is the center of the Universe.

    I love this based-on-new-studies "science".

    Just because we can't see (yet) any other kinds of solar systems, doesn't necessarily mean ours is "special" !

    • Re: (Score:3, Informative)

      by Spatial (1235392)
      They always do that. That's the typical idiotic phrasing in science stories, not the fault of the scientists.
    • Re: (Score:2, Insightful)

      by Anonymous Coward

      You seem to have some sort of bias. Nowhere in the paper, or even the article, is there any mention of GodDidIt.

      The paper doesn't use the word "special" anywhere, though the article does. However, "special" itself doesn't mean goddidit either. One of the dictionary definitions of "special" is "distinguished or different from what is ordinary or usual" which pretty much means the same thing as "uncommon".

      Yes, there are those people that would use the idea that our solar system is uncommon as "proof" that god

    • Re: (Score:3, Insightful)

      by 1800maxim (702377)
      Just because we can't see (yet) any other kinds of solar systems, doesn't necessarily mean ours is "special" !

      Actually, because of current findings, our solar system is quite special.

      When we find other similar solar/planetary systems, ours will lose the special status.

      Sort of like if you have a "special" child in a classroom. Once this child is removed from regular school and placed into a "special" school where all kids are "special", he is no longer "special".

      P.S. What a way to get mod points
  • by jools33 (252092) on Tuesday September 02, 2008 @06:54AM (#24840493)

    From what I've read here: http://exoplanets.org/aasjune07s/pr_280507.htm [exoplanets.org] there have been some 236 exoplanets detected to date. I believe that they have the ability to see if these exoplanets are in highly eliptical orbits or not - so how does this simulation tie with the observed reality?
    The description of Gliese 436 for example seems to also be an exception to this simulation model - so if out of 236 finds we are already finding systems similar to sol - then this simulation model must be at fault or?

  • by w4rl5ck (531459) on Tuesday September 02, 2008 @07:35AM (#24840739) Homepage

    ... currently?

    It's just "educated guessing", nothing more.

  • by HuguesT (84078) on Tuesday September 02, 2008 @07:51AM (#24840835)

    The article says that for a wide range of parameters protoplanetar disks produce a solar system-like outcome relatively rarely.

    The research says nothing about the distribution of parameters in real situations, i.e. is the range of considered parameters realistic?

    This is nice research but only preliminary.

  • "accepted theory" (Score:5, Interesting)

    by JetScootr (319545) on Tuesday September 02, 2008 @07:57AM (#24840879) Journal
    contrary to the accepted theory that it is an average planetary system.
    IIRC, ours is considered typical only because no data existed to show it wasn't. That doesn't make the idea into a 'theory'. Discoveries of extrasolar planets and improved models on more powerful supercomputers are bound to evolve this "Unintelligently Defined Theory" into a better creation story.
    ;)
  • by fireheadca (853580) on Tuesday September 02, 2008 @08:13AM (#24841007)
    ...but slashdot articles about it aren't.
  • by Ngarrang (1023425) on Tuesday September 02, 2008 @08:23AM (#24841087) Journal

    Given the limits of our technology to detect extrasolar planets, how are "they" able to make this conclusion, especially when it is based on simulation? We are able to detect Jupiter-sized planets right now, yes? How about we wait for some better technology that can detect Earth-sized planets more accurately before we go rushing to the idea that we are "special". While the that idea intrigues me, it would certainly make the galaxy a more boring place.

  • They performed 100 simulations and got a result compatible with our solar system. If only 1% of solar systems ended up similar to ours with planets, there would still be tremendous number of similar solar systems out there. I don't think this is anything to be worried about.

  • by paniq (833972) on Tuesday September 02, 2008 @08:43AM (#24841259) Homepage
    our solar system isn't special, it's orbitally challenged.
  • I can just imagine the groans of intelligent life on the elliptical orbit: "Oh boy, here comes the HOT season again!"

  • the only real data we have on planet development to use in a simulation comes from our planets.

    therefore, we can't know about other solar systems until we visit them.

    I'm sure that in the trillions of star systems out there, ours is special. It's special to us. However, I think it's quite common.

  • by argStyopa (232550) on Tuesday September 02, 2008 @09:56AM (#24842269) Journal

    The summary != TFA. Surprise!

    "Due to the complexity of the developing system, which includes the disk-planet and planet-planet interactions described, the simulations resulted in random systems. Nevertheless, two dominant cases were detected.

    In a disk with low mass and high viscosity, the gas in the disk is removed before a planet can form, resulting in a system that has only rocky, icy bodies. At the other end, in a disk with high mass and low viscosity, planets are formed but are pulled towards the center of the system and acquire highly elliptical orbits around the star.

    In the intermediate case, planets form but undergo only modest migration towards the star and their orbits don't become as elliptical. This seems to be the case of the solar system. The simulation showed that this case is realized in a small number of systems, meaning the solar system does not resemble most planetary systems. "

    The report is saying that along a spectrum of possibilities, there are a number which produce results different than our system.
    1) It says nothing about the real life DISTRIBUTION of these alternatives. If only a narrow band of X values produce the results you want, this isn't necessarily a problem if you're in the high point of a steep bell curve. Look at a H-R diagram - there are clearly 'sweet spots' in stellar development across the range of possibilities. Nothing says planetary development is any different.
    2) This of course means little. There is no evidence either way to suggest that life (which is the point of looking for solar systems - I don't think we just have some weird fetish for similar solar systems) can or can't develop on those alternate results. Hell, we may find that solar systems with nearly circular orbits are rare but that's good because they produce the Galaxy's retarded civilizations, and everyone ELSE out there is laughing/pitying us.

    FWIW run your own particle/gravity simulation, and find the same results yourself: http://www.spore.com/comm/prototypes [spore.com]. It's awesome, and finally a use for that uber-mega-cpu you just bought.

  • Converted (Score:3, Interesting)

    by Brass Cannon (882254) on Tuesday September 02, 2008 @10:49AM (#24843237)
    I was once one of the believers. I was sure that Star Trek like civilizations were out there just waiting to shake my hand one day. Then I heard about the Fermi Paradox and the missing link hit me. All of those people who point at the Drake equation are only seeing half of the story. The Drake equation tells us that because of the incredible size of the galaxy, even if the probability of intelligent life is very small, there would still be millions of smart planets. What it fails to address is that not only is the galaxy very big, it is also very old. Assuming that there are lots of intelligent planets out there, and that given our own technology level we could colonize the entire galaxy in about 50 million years if we put our minds to it, we should have seen evidence of some colonization effort from some other civilization by now. Try reading "Rare Earth" to see the long list of things that had to happen to make intelligent life on Earth possible. The basic premise of that text is that basic life (bacteria etc) is common but complex life (plants and up) is either very rare or we are it. There is no paradox. They are not there. We are special.

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