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Space Science

Billions of Habitable Planets? 479

Posted by michael from the every-one-of-them-filled-with-tribbles dept.
cbv writes: "MSNBC has an interesting article about new calculations by Charly Lineweaver and Daniel Grether, both of the University of New South Wales in Australia, which provides an interesting answer to the question on how many potentially habitable planets exist in our galaxy."
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Billions of Habitable Planets? More

Billions of Habitable Planets?

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  • Did they remember to subtract 1? (Score:5, Insightful)

    by blair1q ( 305137 ) on Wednesday January 30, 2002 @03:49PM (#2927068) Journal

    Because by the time we can find another one that is, this one won't be.

    --Blair
    "Keeping up with the Gbrtlrxzes."
    • Actually, we'll probably FIND one in less than 20 years. It'll probably take just as long again to confirm that its actually habitable and to what extent it might already be inhabited.

      Its the next leg of evolution, where we actually manage to amble our way across lightyears to get there. THAT... may take a significant fraction of the rest of civilization as we know it. And while it may take thousands of years to make that next huge step, the planet will be around for billions more yet.

      -Restil

    • Cute, but false. (Score:5, Interesting)

      by Nindalf ( 526257 ) on Wednesday January 30, 2002 @06:27PM (#2927956)
      No matter how badly we mistreat this world, it won't be worse than anything we find out there, unless one happens to have extremely Earth-like life on it already, the kind of place they find all the time on Star Trek, with lumpy-foreheaded humans and grass and spruce trees (foam boulders optional).

      By "habitable" they mean planets like Mars and Venus. Places you can live on in extremely well made air-tight shelters, and maybe eventually terraform.

      We could have a sustained nuclear war (presumably sustained from off-planet), stripping the planet of sophisticated lifeforms and blowing off half of its atmosphere, and it would still be a nicer place to live than anywhere else in our solar system or anything we're likely to find orbiting another star.

      In terms of human habitability, we're taking pretty good care of this one. Wiping out the wilds is sad, but a choice of farms or forests is easy for hungry people. Where it appears unnecessary, done too casually for convenience rather than survival, that is just staying ahead of what the population growth will demand in a generation or two. The pollution looks bad, but it's a feature of short-lived transitional technology, and will tail off before intolerable damage is done.

      On the whole, human effort is greatly increasing human habitability of Earth, not decreasing it. The pristine, wild world of a hundred centuries ago couldn't support half a billion humans, while today it supports well over 6 billion, and the way is being made for 10. Even one century ago, it probably couldn't have sustained half our current population. Things probably won't get tight here on Earth's surface until at least 100 billion, by which time we'll be seriously working on these other places to live. As it is, we haven't seriously dented the resources of our planet, just dug around a little at the choice bits on the surface.

  • The BIG question (Score:3, Interesting)

    by Spamalamadingdong ( 323207 ) on Wednesday January 30, 2002 @03:49PM (#2927074) Homepage Journal
    What will it take to get a program going to actually send people out to them?

    • Re:The BIG question (Score:5, Funny)

      by Scaba ( 183684 ) <<joe> <at> <joefrancia.com>> on Wednesday January 30, 2002 @03:54PM (#2927114)
      I think only telelphone sanitizers, hairdressers and middle management will get to go, if I remember correctly.

    • Re:The BIG question (Score:3, Informative)

      by medcalf ( 68293 )
      What will it take to get a program going to actually send people out to them?

      We appear to be waiting for a crisis, wherein the surface of Earth is sterilized by a marauding enemy. We'll then live underground long enough to retrofit the Yamato as a space battleship, and send her and her brave crew out as the last hope of mankind.

    • Re:The BIG question (Score:2, Insightful)

      by cmpalmer ( 234347 )
      As I mentioned in a previous comment, I think a nice high resolution picture of a cloudswept blue and green plant around, relatively, nearby star would probably be enough -- I just hate that I probably won't be around to find out what it discovers.

    • Re:The BIG question (Score:5, Interesting)

      by s20451 ( 410424 ) on Wednesday January 30, 2002 @04:21PM (#2927279) Journal

      Manned interstellar spaceflight would require:

      • A multi-trillion-dollar committment from the industrialized nations, complete with the political support for a project that could take centuries to implement
      • Propulsion technologies (large-scale solar sails, nuclear / anti-matter propulsion, etc.) and life support technologies that are currently only imagined
      • Orbital construction of a 10-100 thousand ton spacecraft - including shielding, centrifugal gravity, recycling, fuel ... possibly more than one spacecraft, for the sake of redundancy
      • Extensive space infrastructure -- you might want to construct the craft from lunar materials, since it would be easier to launch
      • A few dozen (or more) highly skilled, highly motivated people to operate the spacecraft, are willing to assume the risks of a 20-50 year journey in an untested spacecraft, who would be able to work together in extremely difficult conditions over decades without killing each other, and who would be willing to never return to Earth (maybe even willing to die before seeing the destination, with only their children arriving)

      Some have observed that the level of committment this would require of humanity would be like nothing ever seen before, and which would require devotion that has historically only been commanded by religious quests.

      • How many of these technologies would be worthwhile for other purposes and could be developed for scientific or even profit-making purposes in the mean time?

        (Of course, I'm asking this because nobody is going to devote such resources and focus on one far-off goal long enough to accomplish it; anyone who does will lose other competitions to groups which do not. On the other hand, if the goal can be accomplished via a number of short-term projects each of which is useful and even profitable in its own right, the grand goal follows almost inevitably.)

      • Some have observed that the level of committment this would require of humanity would be like nothing ever seen before, and which would
        require devotion that has historically only been commanded by religious quests.

        Fortunately, there's a "religion" with the right kind of funding to do so!

        Who would ever think something good would come out of Scientology? :>

  • you mean... (Score:5, Informative)

    by youngerpants ( 255314 ) on Wednesday January 30, 2002 @03:51PM (#2927079)
    N = R* × fp × ne × fl × fi × fc × L

    Where,

    N = The number of communicative civilizations
    The number of civilizations in the Milky Way Galaxy whose radio emissions are detectable.

    R* = The rate of formation of suitable stars
    The rate of formation of stars with a large enough "habitable zone" and long enough lifetime to be suitable for the development of intelligent life.

    fp = The fraction of those stars with planets
    The fraction of Sun-like stars with planets is currently unknown, but evidence indicates that planetary systems may be common for stars like the Sun. more info

    ne = The number of "earths" per planetary system
    All stars have a habitable zone where a planet would be able to maintain a temperature that would allow liquid water. A planet in the habitable zone could have the basic conditions for life as we know it. more info

    fl = The fraction of those planets where life develops
    Although a planet orbits in the habitable zone of a suitable star, other factors are necessary for life to arise. Thus, only a fraction of suitable planets will actually develop life.

    fi = The fraction life sites where intelligence develops
    Life on Earth began over 3.5 billion years ago. Intelligence took a long time to develop. On other life-bearing planets it may happen faster, it may take longer, or it may not develop at all. For more information, please visit Dr. William Calvin's "The Drake Equation's fi"

    fc = The fraction of planets where technology develops
    The fraction of planets with intelligent life that develop technological civilizations, i.e., technology that releases detectable signs of their existence into space.

    L = The "Lifetime" of communicating civilizations
    The length of time such civilizations release detectable signals into space.

    • Re:you mean... (Score:5, Informative)

      by LordNimon ( 85072 ) on Wednesday January 30, 2002 @04:11PM (#2927217)
      For those who don't know, the above equation is known as the Drake Equation [activemind.com]. What a lot of people don't realize is that the equation itself is more interesting than the answer, because no one can truly know what values to use for the seven unknowns. To quote the above link:

      The real value of the Drake Equation is not in the answer itself, but the questions that are prompted when attempting to come up with an answer. Obviously there is a tremendous amount of guess work involved when filling in the variables. As we learn more from astronomy, biology, and other sciences, we'll be able to better estimate the answers to the above questions.
    • I think "L" is the problematic one. The term "Lifetime" is deceptive, because it isn't the lifetime of the civilization, it's the span of time that the civilization wastes huge amounts of power broadcasting into space.

      It may well be that most civilizations go through a brief broadcast period and then learn to use point-to-point methods of communication that aren't easily detectable. One reason is simple economics: dumping energy into space is wasteful. But it may also be that successful civilizations actively avoid broadcasting their presence to avoid hostile encounters.

      Here's a depressing thought: they may also consider it prudent to quickly destroy nearby infant civilizations quickly, perhaps by accellerating small chunks of rock to near lightspeed and aiming them at noisy planets. Such an attack could obliterate life on earth with virtually no warning at all.

    • Re:you mean... (Score:5, Interesting)

      by Theodore Logan ( 139352 ) on Wednesday January 30, 2002 @05:32PM (#2927705)
      I've already posted a similar comment in this thread, but since I formulated it rather bad and not too many people seemed to notice I'll make another try. And this time I'll cut and paste from this [faqs.org] site.

      One of the problems that the Drake Equation produces is that if you take reasonable (some would say optimistic) numbers for everything up to the average duration of technological civilizations, then you are left with three possibilities:

      1. If such civilizations last a long time, "They" should be _here_ (leading either the the Flying Saucer hypothesis---they are here and we are seeing them, or the Zoo Hypothesis---they are here and are hiding in obedience to the Prime Directive, which they observe with far greater fiqdelity than Captain Kirk could ever muster). -or-

      2. If such civilizations last a long time, and "They" are not "here" then it becomes necessary to explain why each and every technological civilization has consistently chosen not to build starships. The first civilization to build starships would spread across the entire Galaxy on a timescale that is short relative to the age of the Galaxy. Perhaps they lose interest in space flight and building starships because they are spending all their time surfing the net. (Think about it---the whole point of space flight is the proposition that there are privileged spatial locations, and the whole point of the net is that physical location is more or less irrelevant.) -or-

      3. Such civilizations do not last a long time, and blow themselves up or otherwise fall apart pretty quickly (... film at 11). Thus the Drake Equation produces what is called the Fermi Paradox (i.e., "Where are They?"), in that the implications of #3 and #2 are not terribly encouraging to some folks, but the two flavors of #1 are kinda hard to come to grips with.

      An alternate version of 2 is that interstellar travel is far more difficult than we think it is. Right now, it doesn't seem much beyond the boundaries of current technology to launch "generation ships," which power systems. An
      alternative is robot probes with artificial intelligence; these don't seem so difficult either. The Milky Way galaxy is well under 10^5 light years in diameter and over 10^9 years old, so even travel beginning fairly recently in Galactic history and proceeding well under the speed of light ought to have filled the Galaxy by now. (Travel very near the speed of light still seems very hard, but such high speed isn't necessary to fill the Galaxy with life.) The paradox, then, is that we don't observe evidence of anybody besides us.
      • An even more elaborate discussion of the consequences of this line of reasoning can be read here [ndirect.co.uk].

        Too bad discussions on Slashdot die so quick. This one could have been fun!

      • Short lived civilizations could be good, not bad (Score:5, Insightful)

        by FreeUser ( 11483 ) on Wednesday January 30, 2002 @11:10PM (#2929149)
        3. Such civilizations do not last a long time, and blow themselves up or otherwise fall apart pretty quickly

        Or alternatively, civilizations progress at a geometric rate, transcending themselves in a few short generations, so that by the time intersteller travel becomes feasable they have lost interest and moved on to more compelling possibilities (perhaps departing this frame of reference entirely).

        Once one hypothesizes a civilization significantly more advanced than our own it becomes difficult to even imagine the technologies they may have, much less what interests they would find compelling, or what goals they might set for themselves. For all we know they are all around us, unrecognized because they operate at levels as far beyond us as we are beyond the simple microbe.
  • I want my own planet. Of course, you're all invited as guests - I should have plenty room.
    • If you want your own planet may I perhaps suggest you become a mormon?

      From this website [leaderu.com]

      Celestial (Heaven) - for Mormons who have kept ALL of the laws and ordinances of their church. What will the celestial heaven (kingdom) supposedly be like for a good Mormon? He will be a god, he will rule over a planet with his wives and spirit children.

      laugh, its a joke

  • this is a WAG, nothing more, nothing less. (Score:4, Insightful)

    by Em Emalb ( 452530 ) <ememalb@gm a i l . com> on Wednesday January 30, 2002 @03:53PM (#2927101) Homepage Journal
    "For now, no one knows whether our solar system represents a common method of formation and evolution. In fact, discoveries over the past six years seem to indicate otherwise. Most of the roughly 80 planets discovered outside our solar system are much more massive than Jupiter. They also orbit perilously close to their host stars, locations that would likely prevent rocky planets from forming in so-called habitable orbits.
    But experts attribute these findings to the limitations of technology. "

    Hmm, WAG anyone? Wild assed guess for those that are AC (Acronmyn-Challenged).

    I would bet a terabyte of New Zealand Sheep porn that tomorrow there will be 500 stories debunking this. More "proof by way of media" sounds like to me.

    I loved this comment:
    '?Our solar system is Jupiter and a bunch of junk,? as Lineweaver puts it.'

    Yeah baby, I live on a hurling mass of yesterdays dinner and some junk mail....wohooo.....
    • Hmm, WAG anyone?

      More properly, a SWAG. You seem to have acronyms on the brain, so you can figure that one out. :) Actually, they qualify it pretty well, I think - they state that the 80 or so planets they've discovered are far larger than Jupiter/closer to star system, yadda yadda. But they're right - the only reason they see these planets so frequently is because they're the only planets we can currently see. IIRC, the method they use to detect planetary objects is to subject the emissions of the star to very precise Fourier analysis, or other frequency analysis, and thereby detect very slight frequency shifts in detected emissions - Doppler shifts corresponding to slight motions of the star due to the influence of the planet on the star. Naturally, that influence is small, and it's only measurable above the noise floor, currently, if the planet is truly ginormous. Smaller planets don't influence stars enough that we can see it with current methods - so their statement stands, I'd say.

      I think the real question is this: why the heck do you posess terabytes of sheep porn? :)
    • > For now, no one knows whether our solar system represents a common method of formation and evolution.

      True. And as for habitability, has anyone considered the importance of plate tectonics and tides for life? Or the possibility of a causal relationship between massive collisions early in a planet's existence, and extended periods where plate tectonics continues?

      Compare Earth, Venus, and Mars:

      Venus: Probably no massive collision early in its life. Boring world, no way for CO2 to be recycled into a big liquid water carbon sink. Looks geologically-dead.

      Mars: A mostly-geologically-dead world, too small to retain much of its original heat, and, of course, no massive collision early in its life. Had liquid water once upon a time.

      Earth: Smacked by a Mars-sized impactor early in its life. Debris coalesced to form huge satellite called "the Moon". Frighteningly geologically-active. Big-ass oceans sink lots of CO2. Plate tectonics keeps it underground rather than letting it vent into the air.

      A sample size of "three" is pretty slim, but to my (untrained - any exogeologist-types out there care to comment?) mind, the facts that Earth got whacked and the fact that the Earth still has a thin crust (while Mars, and more interestingly, Venus, have cooled off) appear to be more than coincidence.

      Bring in an exobiologist -- perhaps "tides" (think "tidal pools" are handy for forming life. Also think about the impact that tectonic activity (and life) has in recycling CO2 on Earth.

      Does anyone know if Earth's core is "too hot" to be accounted for simply by heat from 4.5 billion years of radioactive decay of its initial components?

      I'm speculating that the impact that created the Moon also added a metric buttload of heat to the still-forming planet's core, while simultaneously stripping the proto-Earth of some of its lighter silicates. If the impactor came from "far enough away" in the solar system, it may have brought a metric buttload of water ice with it. The result was a glob of metal-enriched rock, water, water, everywhere, a double-planet system with tides (useful for future development of life) and recycling of crustal material via plate tectonics due to the planet's thin crust.

      (jumping off the deep end into wild-ass speculation now...)

      Perhaps this is another reason to go to Pluto. Perhaps the Pluto/Charon system formed in a manner similar to Earth/Moon. If we found evidence that Pluto had a metallic core, and that it was warmer than could be accounted for by radioactive decay...

      If we assume (or can demonstrate) that things like plate tectonics and tides are "good" for the formation of life (at least, they seem "better" than the situations on Mars and Venus that arose from the lack thereof), it'd be nice to know that early massive impacts were common. It'd be even nicer to know that there was a correlation between such impacts and "warm" planets with lots of water.

      (Sigh... still holding out for the day we see the spectrum of light reflected from a rocky planet in orbit around another star... a spectrum showing lots of oxygen that should have reacted itself away by now unless something on the planet's surface was replenishing the supply...)

      • Metrics... (Score:3, Offtopic)

        by DrCode ( 95839 )
        Can anyone tell me the difference between a 'metric buttload' and an 'Imperial buttload'? Thanks.
    • Yeah, no mention of the fact that the only way we've detected other planets is through their gravitational influence on the stars their orbiting. Obviously any planets we detect will have to be huge, until we have the technology to detect smaller planets. It's ridiculous logic to draw a conclusion then that most planets out their are huge.

    • Re:this is a WAG, nothing more, nothing less. (Score:4, Funny)

      by rho ( 6063 ) on Wednesday January 30, 2002 @04:42PM (#2927409) Journal

      I'm more interested in that terrabyte of NZ sheep porn, myself...

  • Why live on planets? (Score:2, Interesting)

    by Ectropy ( 546881 )
    By the time we have the sufficent amount of technology for exploring the billions of Eaths out there, I am sure we will have plenty of technology regarding space stations. The only purpose I see in colonizing planets is for just mineral mining and for exploration. There should be no need to try and terraform or have to shape the Earth-like planets to our needs, we should just build space stations. At least then we do not have to worry about having insuitable worlds, or worlds that are unproductive. Also, a space station would be customizable for purpose and for people. There is no need to colonize many planets!
    • I don't agree with this.
      After all, why invest all the time and resources and everything to build a floating planet?
      There's already one there, why not use it?
      My money is going to be more on habitat controls than planet-sized space stations.
      Here's what I see as a more likely scenario:
      We find a nice planet to inhabit, pick out the most strategic locations for civilization hubs, send in teams to build the hubs, and slowly expand the hubs as people come in.

      So to sum up:
      We're probably going to colonize planets one at a time, and live on a solid, natural surface. We are not going to build a zillion death star type space stations and live life zipping around the cosmos.
      but hey, I'm always up for a debate...:-)
      • But we only live on the surface of the planet, which catches only a tiny fraction of the energy the sun makes available; in the long run there's a lot more room out there between the planets than on them, and I hear the view is spectacular...

      • Re:Why live on planets? (Score:3, Interesting)

        by znu ( 31198 )
        I expect by the time we have useful interstellar travel, we will have reached the point that raw materials and construction are essentially free. Building space habitats is cheap with the right tech. All you do is set a few self-replicating robots loose in an asteroid belt. Of course, teraforming planets is cheap too, with that kind of tech (plus the sort of biotech we'd probably have by then), but it still takes a really long time.

        Maybe if the planet is earth-like enough that you can just land, go outside in your T-shirt, pitch a tent and stay the night, it'll get colonized. But there isn't much point if you have to do any serious work, like, say, replacing a reducing atmosphere or getting more water from somewhere.
        • Asimov's Nemesis? What about the Niven's RingWorld? Doesn't it make sence to live close to a star to derive as much energy from it as possible?

        • Just because resources are free, does not mean they ar eunlimited. There is a finite amount of bas emetals in the earth, such as iron and soforth. Removing enough to construct the space stations you describe (enough to hold a planet's worth of people) would require the resources of more than one planet.

    • Maybe people like those Big Blue Rooms?
    • I think we'd become the nanites in the Grey Goo [logica.com] scenario, only we'd be able to jump from planet to planet. We humans tend not to know when to quit exploiting something for its resources. Or is there nothing wrong with doing this to an uninhabited planet? (I'd like to hear opinions on that)
    • What a drag!

      Technically, I'm sure you're correct. By the time we are able to travel to other planets, they will probably not be a necessity; but what a bleak picture of life that presents.

      I guess I have too much affection for sunrises, rivers, mountains, cool breezes, etc.

    • Gravity.

      There are a number of problems with space colonization, but one of the killers is gravity.

      But what about oxygen, food, etc you may ask?

      Gravity takes care of the containment for you. Your gravity isn't going to spring a leak and start venting air away (assuming it is great enough to hold it in place at a proper pressure).

      Further, without physical stress (ie: weight) bones/muscles deteriorate requiring more maintanence to keep the human colonists functional.

      Food: A planet provides a MASSIVE surface area with which to grow crops (even if the soil is unarable, large hydroponics systems could deal with it). A self sustaining station would require massive amounts of materials to make a farm large enough to feed its inhabitants. Let alone if a small asteroid came along and broke the ceiling out of your greenhouse...

      Assuming you aren't eating nutritional pills by then.
    • Planets are much larger than space stations.

      Planets have more available resources than space stations.

      Planets with a proper ecosystem naturally recycle the elements needed for life, mainly in our case, Oxygen and water.

      While a 6 mile wide asteroid can cause serious damage to both space stations and planets, planets are pretty damn impervious to baseball sized rocks (of which in space there are many many more) where space stations can be quite devestated by them.

      The magnetic fields and atmosphere of planets filter out a lot of dangerous radiation which space stations need to take special care with.

      Planets aren't going anywhere quite yet I feel. :)

      -Restil

  • Old Hat (Score:3, Interesting)

    by stipe42 ( 305620 ) on Wednesday January 30, 2002 @03:57PM (#2927136)
    This article doesn't present anything more than the now cliched "well if just one percent of stars have planets and one percent of those are in a habitable zone and . . ."

    The only original take is that those 'one percents' are getting replaced with percentages actually based in reality.

    Speculations like this used to be popular because astronomy was nowhere near the technology needed to actually see planets out there. If I remember correctly, the first true proof of planets around other stars occurred around 1995 when these first gas giants started to be detected.

    With the detection methods getting better every year though, it's only a matter of time before we can directly detect terrestrial sized planets around other stars. That's the point where these statistical guesses get kind of silly.

    "I bet there's a thousand planets out there!"

    "Actually, there are 1422. We can just count them now."

    stipe42
    www.pcwatch.com [pcwatch.com]

  • more than half (Score:5, Funny)

    by Paradise Pete ( 33184 ) on Wednesday January 30, 2002 @03:57PM (#2927140) Journal
    The most remarkable fact from the article:
    We found that of all planets just reaching the dawn of their personal computing era, more than half of them have a whiney guy in glasses writing letters to magazines complaining about people not paying for his BASIC interpreter.
  • The guy is right that having Jupiter as a shield definitely has made a difference in Earth's ability to support life over the long term; however, he doesn't touch on what might the more significant fact: our solarsystem is located in the boondocks of our galaxy. What this means is there is a whole lot less debris floating around to smash into earth. The closer you move towards the galactic core, the more crap there is and the less effective a Jupiter shield would be.
    • Being out in BFE means a far smaller likelihood of another star passing close enough to perturb the orbits of all the planets in a system. The impact of comets can change climate briefly, but with a huge effect on life; think what a semi-permanent (until the next perturbation) change in climate could do to life which had evolved for a particular set of conditions. A few trips through an over-greenhoused state would be enough to wipe out most everything but extremophile bacteria, making it very unlikely that higher life forms (let alone intelligence) could develop.
    • This is true, however, as the outer layer of any shape has the largest volume, then there will be no shortage of solar systems out here in the boonies.

  • The population of the universe is 0... (Score:3, Funny)

    by Anonymous Coward on Wednesday January 30, 2002 @04:01PM (#2927161)
    From Douglas Adams...

    Number of Planets in the Universe = infinity
    Number of Populated Planets in the Universe = N

    n
    --------- = 0
    infinity

  • “A reasonable guess" (Score:3, Insightful)

    by CyberHippy ( 541868 ) on Wednesday January 30, 2002 @04:06PM (#2927190) Homepage
    "A reasonable guess is the same number of Earths as Jupiters," Lineweaver said.

    How the hell is that a "reasonable" guess? Even assuming the definition of "Jupiters" requires that it be exactly like ours, we can't assume that just because a "Jupiter" forms that an "Earth" will too!

    I agree that it is reasonable to assume that a habitable Earth requres a comet/asteriod blocker, but the presence of a Jupiter does not imply the presence of an Earth.

  • Asimov (Score:3, Interesting)

    by anti-snot ( 555305 ) on Wednesday January 30, 2002 @04:08PM (#2927199)
    This argument is oddly reminding of the one from Asimov's Robot Novels. In essence, he claimed that a relatively rare large moon constantly kneads the earth's surface, bringing radioactive materials to the surface and accelerating the rate of mutation enough to afford effective evolution.
  • so the argument goes that since jupiter in some manner made life possible for earth, and total destruction for many other planets . . . this doesn't sound like a very intelligent way of going about it at all! "Hey, let's find all the giant planet destroyers because they sometimes, in very rare and complicated circumstances, factor into making possible in their own limited way!" somehow, i don't think so.

  • How many? (Score:4, Funny)

    by Insightfill ( 554828 ) on Wednesday January 30, 2002 @04:12PM (#2927228) Homepage
    <sagan voice>

    ...Billions and Billions...

    </sagan voice>

    Boy, I'll miss that guy! One of the many people who triggered lots of tech interest in me and made me who I am!

  • High estimate... (Score:2, Insightful)

    by Arcturax ( 454188 )
    Very high... 30 billion jupiters != 30 billion earths. Just because there is a jupiter sized world (even assuming similar orbit instead of an insanely close orbit to the star) doesn't mean anything else useful formed inside its orbit. However if even .01% of those have conditions even approaching those required for life (like Mars) then chances are good for there to be hundreds of even thousands of intelligent species out of maybe a few tens or hundreds of million worlds of most likely algae and microbes.

    So in short, I think this guy is nuts to suggest billions of earths. Maybe millions (tens or hundreds) in the venus->mars range but not billions.

    • I suppose it depends on what you mean by "intelligent". Dinosaurs were intelligent, so were mastadons, so are dogs and cats and gorillas and birds. If you mean intelligent as in technologically adept as human animals are, there is no reason to assume that there are a lot of those.


      If it were not for an accident 65 bya, there would be no humans and dinosaurs might well STILL have run of the planet. There is NO imperative for technological intelligence or development for that matter. If not for the Europeans coming to the North America, the native Americans would still be quite healthy and happy living as the always had - they had no technological development beyond what was necessary and useful to them. The Commanche were not technologically superior to the people of Mesa Verde/cliff dwellers simply because they came later. I am not in any way dissing native Americans but am simply making a point...if not for the Europeans with THEIR accidental technologically-based society coming to North America, the natives would most likely STILL be living as they have for hundreds of years.


      So, there may well (and likely is) many habitable planets. There is likely MANY locations with some form of life. It does NOT follow that there must be lots and lots of technologically advanced societies. A few here and there, perhaps, with an unknown fraction of those killing themselves off due to war or polluting themselves out of a home, with the survivors being few and far between.


      That said, there is no reason to assume a priori that they would be any better about space exploration than we are. It is COSTLY to go into space. It is especially costly to put people into space. It is EXTREMELY costly to colonize space. I would also doubt that there is any spiffy way around basic rules like lightspeed barriers, etc, so it is not even a given that their spacecraft, robotic or not, can get very far in any reasonable amount of time. There is no reason to assume that machines can ever be produced that would be so much better than living things at self repair (EVERYTHING makes mistakes and they are usually detrimental - evolution isn't as simple as saying "machines will make mistakes self-replicating in a way that will permit evolution to occur there too). So some technical society launches a probe to a nearby star. Maybe it gets there within a reasonable amount of time so that those back home are still willing and able to listen to its transmissions back. Maybe they launch it and then collapse and the whole project was moot. Maybe they go for a while, expand a little within their solar system and then slowly crap out...millenia before WE came along. We just missed them by a few thousand years.


      The real possibilities are endless and at least some of what I am stating here addresses the Fermi Paradox (which is, of course, itself based on the false assumption/conceit that advanced intelligence means technology which means space travel, etc). Dinosaurs, et al, were HIGHLY intelligent and advanced compared to cyanobacteria. They were HIGHLY advanced and intelligent compared to virtually everything that came before (and many that came after).


      There is NO technological imperative in biology/evolution.

  • Puh-leez! (Score:3, Funny)

    by Cynical_Dude ( 548704 ) on Wednesday January 30, 2002 @04:13PM (#2927236)
    Thinking that Earth is the only inhabitable planet in the galaxy or even the universe is so last millenium.

    It doesn't take a genius (just a bit of open-mindedness) to figure out that in the vast reaches of just our own galaxy (not to mention the universe) the chances are good that additional systems similar to Sol were formed.

    Remember: The absence of proof is not the proof of absence.

    On a lighter note, I really hope they'd hurry up and colonize another planet. Then, next time some ecologist gets on my nerves by saying: "THINK OF THE PLANET!" I can retort: Sheesh, it's not like it's the only one we've got!".

    And yes, I know I stole that from Futurama ;)

  • Anyone who believes that there is not an assload of planets that could possibly support sentient life is incredibly arrogant.

    Anyone who believes that a "god-like being" would only create life on a singular planet is even more arrogant.

    Anyone who believes that we will be able to easily find them within the next century is naive.

    Anyone who thinks that people will be sent to any such planets found within the current century is a tool.

    Remember, the earth is not the center of the universe (unless of course, all points in the universe are equidistant from every other point, then every point is the center of the universe, which would really mean it has no center. But what are the odds of that...).

    That being said... I wouldn't mind taking a ride on a monkey fueled liquid nitrogen cooled rocket sleigh to some far off planet and get it on with alien chicks with 2 bellybuttons, like William Shatner.

  • Jupiter-like planets offer 2 chances for life (Score:5, Interesting)

    by Jason Levine ( 196982 ) on Wednesday January 30, 2002 @04:18PM (#2927259) Homepage
    As the article says, Jupiter-like planets can act like a debris-magnet to protect Earth-like planets from comets, asteroids, and the various other junk floating around solar systems. Their immense gravity can either force and object out of the solar system entirely or force it to collide with the large gas giant. (An impact which would leave Earth near-barran for centuries is barely felt on Jupiter gas giant.)

    The moons of the Jupiter-like planet offer another possibility for life. Like Europa, gravitational stresses from orbiting such a large planet can cause heat to warm up a normally frozen world. This heat might help melt ice into water (as is thought to be on Europa under the ice shell). And where there's water, life might not be far behind.

    Now this isn't to say that life=intelligence. We might be talking about the ET equivalent of bacteria, here. Still, the discovery of ET-bacteria would be a huge matter.
  • Another habitable planet might be a good idea but we (apparently) won't be needing it very soon (barring the actions of the Bush EPA).

    Frankly, I've always wondered why the rush to find other civilizations. Unless we confidently expect to be able to do to them what Cortez did to the Aztecs, I think the best idea is to hope the Earth stays hidden from prying eyes. Afterall, we may be Aztecs to them! And since when has a lesser civilization benefitted from meeting a superior one?

  • before you go bonkers about this (Score:3, Interesting)

    by Theodore Logan ( 139352 ) on Wednesday January 30, 2002 @04:26PM (#2927312)
    ...and deduce that there are quadrillion intelligent lifeforms out there, remember what Fermi said about all these fancy equations (and that has later become known as "The Fermi Paradox"):

    If there are aliens, where are they?

    Sounds silly? I agree. Sounds like "The Fermi Paradox" is too fancy a name for a natural objection? I agree on this too. However, when you think about it, it becomes fairly obvious that it really is the only argument in this debate that is somewhere between strong and very strong.

    • We've got chemical rockets. We can pretty accurately estimate what a fission rocket, fusion rocket and an anti-matter rocket can do (in order of increasing power), and frankly, it's not that damn impressive compared to the insane distances of space.

      Radio signals? How should we send, what solar systems, what frequnencies, what intensity, what signal type? Likewise goes for listening. SETI is looking at one extremely small area of the sky, and yet it needs an extremely powerful signal, only the most powerful of radars aiming precisely for earth would be detected. And even then it could be put off as static, or a burst by some natural phenomen.

      We could use a Warpdrive and a Sub-space communications system. But some sci-fi isn't going to be sci-fact ever, of course there's no telling which in advance.

      Kjella

    • Re:before you go bonkers about this (Score:4, Interesting)

      by sheetsda ( 230887 ) <doug DOT sheets AT gmail DOT com> on Wednesday January 30, 2002 @05:01PM (#2927512)
      If there are aliens, where are they? ... However, when you think about it, it becomes fairly obvious that it really is the only argument in this debate that is somewhere between strong and very strong.

      I don't know if there are any correlaries to this Fermi Paradox, but based solely on your post I think Fermi made waaaay too many assumptions. Lets see...
      • They're not advanced enough for us to locate?
      • They're too advanced for us to locate?
      • They don't want to be located or at least located by us? (as in actively seeking to hide)
      • They don't care to be located? (as in not hiding but not shouting "hey here we are!")
      • They don't care to locate others?
      • They have not yet been able to contact us because our ability to receive signals has only been around 100 years, and they're, oh, 500 lightyears away?
      • We still have no idea how to receive their signals?
      • They have no idea how to send signals?
      • They don't believe we exist?
      • They too have a Fermi Paradox?

      I could go on forever. I don't consider this a strong argument. I prefer the approach of statistics, even if it can yield no answers based our on current lack of information.
      • I can agree that all those are natural objections, as long as you presume that "they" are not too many. Otherwise, you may have a problem. The Fermi paradox could be said to be based on the following premise:

        Either only Earth have a technologically advanced civilization, or many planets do.

        It is, in other words, not the case that only "a few" planets have highly developed civilizations. By many is meant at least in the order of a billion or so. I'm sure you can figure out why this premise is not unreasonable for yourself. Now, the argument goes, maybe the objections you raise are valid for some of the civilizations, but it would incredibly naive to think that they (or, to be more precis, at least one) would be for all of them. Even if what you say would be the case for 99% of them, there would still be many millions left.

        This is, however, an interesting debate, albeit an old one. Feel free to reply if you think something is seriously wrong with the line of reasoning outlined above.

    • >If there are aliens, where are they?

      Perhaps they are waiting for us to grow out of our infancy. I mean, do you really think we're really to handle that sort of idea? Let's take a look a high level look at our planet:

      • Over 30,000 humans (mostly children) die each day of hunger when there is plenty of food for everyone.
      • We poison our environment (or world) and somehow expect this to not affect us. Clean alternatives are available but they aren't used.
      • We haven't learned to stop killing each other. The fact that we all really want the same basic things seems to escape us, as well as the fact that those things (happiness, peace, etc) require nothing except for our willingness to give up our deadly attachments to those things which really aren't doing us any good but that we think will make us happy (money, glamor, power over, etc).


      • It seems to me any highly evolved race would know well enough to keep their distance and wait to see if we destroy ourselves before initiating contact (especially if they knew, like a wise parent, that we have to figure these things out for ourselves).
  • If you are looking for billions of habital intelligent planets, your probably off the mark. I think that it is more likely that there are bacteria or something of that nature on some of these other planets. But that is just my opinion.

    Fact is that if there was life on another planet we would not be able to get there with current technology and understanding of physics. It would take to long traveling at what scientists today call the maximum speed limit 'the speed of light'. Maybe someday when we understand space and time better but not now.

    Watch Discovery channel now and then as they already went over alot of this stuff. They made a discovery a while ago and discovered how to detect the 'gas giants' as they call them (jupiter / sturn sized planets) orbiting a star by watching the stars wabble.

    And for you real space fanatics http://www.spaceref.com/ and www.space.com are great sites.

    Lastly I cant type and spell so don't point out my typoes and spelling errors it is really laim.

  • Great, as soon as they reveal their locations their going to get spammed.

  • Universal Sterilization program (Score:3, Interesting)

    by PaulGibson ( 552064 ) on Wednesday January 30, 2002 @04:40PM (#2927393)
    I saw a NOVA episode recently where the occurrance of pseudo or genuinely random bursts of radiation are visible from Earth. They (some very astute astronomers) have been figuring out what is up with them for some time. They have proven so far that they originate from a very long distance from our galaxy, and go on to say that any life that is in the beam will be immediately sterilized. The bottom line was that there may likely be other earths out there, but the likelihood that they are safe from this radiation is very small. It seems that they have discovered that we are safe enough, as the radiation is caused when massive stars collapse. The star size has to be something very much bigger than any star they have actually located in our galaxy. I can't remember the size estimation, but it was orders of magnitude larger than our sun (a medium sized star).

    Our universe is probably a mere atom inside a larger universe, and these radiation bursts are simply the efforts of their Einstein trying to split us.

  • Only discusses HABITABLE worlds. (Score:3, Interesting)

    by Restil ( 31903 ) on Wednesday January 30, 2002 @04:55PM (#2927475) Homepage
    But not the worlds that have developed life or advanced civilizations. There's a big difference.

    Its also fair to wonder, how many spacefaring civilizations are there? By that I don't mean, how many have launched someone into space, but how many have actually colonized worlds outside of their home solar system?

    It has been shown, that given extremely slow, but reasonable travel times between stars, and assuming it would take 500 years (for an already technologically advanced society) to develop a world and the rest of the solar system, then advance on to the next one. With this in mind, such a civilization would only require about 3 million years to completely colonize the galaxy. Considering the billions of years the galaxy has existed, 3 million years is but a brief moment in time. If it was going to happen, it would have already happened.

    Now consider our own situation. We're 4.3 light years from the nearest star. We're in the perfect location to drop off a few test subjects (humans with no technological knowledge) and see what happens. It would take a long time before they'd discover what really happened. And others could observe and reflect in that time.

    -Restil

  • Safety and Security. (Score:5, Funny)

    by Talinom ( 243100 ) on Wednesday January 30, 2002 @04:55PM (#2927477) Homepage Journal
    I don't care how many worlds there are in the Galaxy. I'm NOT going to wear a red shirt when I beam down to one of them.

  • Other factors (Score:3, Interesting)

    by jafac ( 1449 ) on Wednesday January 30, 2002 @04:56PM (#2927482) Homepage
    Don't forget that the degree of axial tilt AND periodicity of axial tilt oscillation are thought to play a huge role in climate change cycles, and therefore the formation and evolution of life.

    How many planets of the right size, right consitution, right size and distance and periodicity of large satellites, right distance from sun, right periodicity of solar orbit, right periodicity of rotation, right frequency of asteroid collisions, right strength of magnetic field, right type of sun, right stage of solar lifecycle, right stellar neighborhood (no local supernovae). . .

    Seems pretty farfetched to me.

  • .com flashback (Score:2, Insightful)

    by TheLastUser ( 550621 )

    The reasoning reminds me .com marketing.

    How many people surf the web?

    If only 1% of those people come to our site, WomenWithoutBras.com, then, at a $10cpm, we will make 42 billion dollars a month, wow!

    Want to buy some stock?

    Eventually, when we stop sending astronauts into orbit to monitor mice having sex, and put up some decent astonomical instruments, we will be able to image some Earth sized worlds, and then we will forget all about the statistics.

  • Rare Earth (Score:3, Interesting)

    by artemis67 ( 93453 ) on Wednesday January 30, 2002 @05:16PM (#2927623)
    Personally, I have to say that I lean towards the conclusions found in Rare Earth [amazon.com] by Peter Ward and Donald Brownlee. I think they make a very compelling argument for there being far fewer earth-like planets than all of these starry-eyed astronomers are predicting.

  • The Problem with Space Travel (Score:3, Interesting)

    by rudy_wayne ( 414635 ) on Wednesday January 30, 2002 @05:28PM (#2927686)
    Science Fiction has clouded our vision of reality. Consider:

    Nearest star is just over 3 light years away, so, traveling at 1/10 the speed of light, it would take you 30 years to get there.

    1/10 speed of light = 66.9 Million Miles per Hour

    Therefore, the problem becomes:

    You must somehow build a spacecraft that can travel at 66.9 Million Miles per hour, non-stop for 30 years, and can accomodate a crew for that same 30 years.
    • You must somehow build a spacecraft that can travel at 66.9 Million Miles per hour, non-stop for 30 years, and can accomodate a crew for that same 30 years.

      No, you dont. You must build a spacecraft that can _accelerate to 66.9 Million Miles per hour, and deccellerate a few decades later.
      Once you have picked up speed in space there is no additional effort to keep it, since there is very little friction in the near-emptyness of space.

      You are right about one thing though.
      Interplanetarry travel is a lot harder than most people think...

    • Read Nemesis (Isaac Asimov). BTW. by the time a large spaceship like that goes half way to the star we would have developed technologies allowing us to go back and forward to and from the star 100 times a day. Poor crew of that ship would have arrived to the star only to visit McDonald restaurant!
    • As soon as I start being dreamy about space travel, there's gotta be someone on /. to pull me back into reality.

  • the technical article (Score:4, Informative)

    by awhoward ( 108214 ) on Wednesday January 30, 2002 @05:31PM (#2927702) Homepage
    here's the technical article (on the preprint servers):

    http://xxx.lanl.gov/abs/astro-ph/0201003


  • Ever heard of a little something called binary black holes?


    This little thingies has two tightly focused, _really_ hot jetstreams of radiation going out in opposite directions, but doesn't emitt much in other directions (They're black holes after all, so they suck up pretty much everything that could make them detectable).


    Well, now imagine a spinning binary black hole.
    It'll be almost undetectable... until it happens to spin so that one of the jetstreams hit a planet and fry it to a crisp.


    We _could_ have things like this just around the corner (astronomically speaking) and not be aware of it.


    I don't know how common this type of celestial bodies are, but for life, they are definitly a Bad Thing, since they could effectivly "reset" a planet and life would have to start all over again...

  • Asimov has many life-capable planets out there in this Foundation universe (and several other stories). However, none have developed intelligent life. 90% of earths history was like
    that. You'd just see deserts and a little bit of scum in the water. Worms and such developed in the last 12% of the earth's age. Fishes and plants in the final 6%.

  • What about the Moon? (Score:4, Interesting)

    by roman_mir ( 125474 ) on Wednesday January 30, 2002 @06:10PM (#2927892) Homepage Journal
    Do we have all the facts to say for sure that the Moon had nothing to do with formation of life and maybe even of intelligent life on this planet? Our closest neighbour is only 300,000km away from us and it is also a HUGE satellite for our planet. It has a profound effect on this planet, an effect that Deimos and Phobos of Mars can only dream about. How about tides that Moon enforces on our largest pools of water? It is possible that life was created specifically because of these tides, in the puddles of water that were left behind a tide (well that's a theory anyway).

    So, how many of those planets have comparable Moons around them?

    • Re:What about the Moon? (Score:4, Insightful)

      by mperrin ( 41687 ) on Wednesday January 30, 2002 @07:44PM (#2928286) Homepage
      Tides aren't a substantial argument. The sun's gravity produces tides on the Earth as well. The amplitude of solar tides is about half that of lunar tides, so even the complete absence of the moon doesn't imply there would be no tides. They'd just be somewhat smaller.

      Beyond that, there's an increasing body of evidence that early life was highly extremophilic and more likely formed deep underground or near a deep-sea hydrothermal vent. I don't know of -any- hard evidence that tidal pools played a large role in biogenesis; it's all speculation as far as I know, though I'm admittedly only an astronomer, not an astrobiologist.

    • Re:What about the Moon? (Score:3, Interesting)

      by Corgha ( 60478 )
      [I'm no planetary scientist, so you'll have to forgive any inaccuracies, and maybe someone who knows a little more will correct me.] One possible reason for the importance of the Moon (if one believes it originated in an impact) is that it may contain a great deal of light outer-crust rock that would normally be on Earth.

      Earth has these little continents that leave the thin tectonic plates (made of denser rock and covered with vast oceans) free to move around. Imagine how different Earth would be if all the rock that currently orbits us were instead filling the ocean basins and keeping the plates from moving around.

      A few back-of-the-envelope (containing some stupid coupon from AT&T Broadband) calculations gives about 2x10^19 m^3 for the volume of the Moon, 5 x 10^14 m^2 for the surface area of the Earth, so, spreading the moon out evenly (and neglecting curvature), a layer 4 x 10^4 m thick. Granted, it might not all be silicate, but it's a lot of rock, especially considering that the average depth of the oceans is around 4 x 10^3 m, and the plates under the oceans are around 5 x 10^3 m thick (results of random web searches).

      Something to think about the next time you look up at the Moon.

  • Great offer!!! (Score:3, Funny)

    by Futurepower(tm) ( 228467 ) <M_Jennings @ not ... futurepower.org> on Wednesday January 30, 2002 @06:14PM (#2927914) Homepage

    I will give you half of my share of the planets if you can tell me how to get there and back, safely and for a reasonable price.

  • This is what we should do: (Score:4, Interesting)

    by rice_burners_suck ( 243660 ) on Wednesday January 30, 2002 @06:52PM (#2928048)
    Combine this discovery with technologies such as global computer networks, advanced robotics designed for many purposes, the ability to genetically engineer any kind of living creature and terraforming technology, and we'll be able to create entire ecosystems that produce some intended results. Call it a computer--or more accurately, a machine--the size of a planet, with its output being anything from mined materials to manufactured consumer and business products to medicines and chemicals that are hard or impossible to produce on Earth. Nobody said the atmosphere on those distant planets need to contain oxygen--they could be saturated mostly in carbon-dioxide so that genetically engineered plant life could thrive, making unbelievable things possible. Imagine... on a distant planet, where plants grow extremely fast, robots cut down millions of trees every day and ship them to Earth. No longer would it be necessary to kill trees on Earth for houses, furniture, or even paper! Materials could be mined from distant planets. Why use up our own oil, metals, minerals and whatnot, when we can mine and retreive it from another planet? Why pollute our own atmosphere to manufacture things if we can manufacture them on other planets and let those planets get polluted? If designed correctly, those planets won't even get polluted! But who cares if they do?! Garbage crisis? No problem! Put it on another planet. The beauty of it is that no human being would actually have to set foot there! The robots could fix each other when they break down, and could be remote controlled from Earth, just like the Mars lander. It would be very beneficial to all of mankind, and would open up unbelievable multitrillion dollar international businesses that deal in interplanetary sales and distribution.

  • Billions of Habitable Planets (Score:3, Interesting)

    by NeuroManson ( 214835 ) on Wednesday January 30, 2002 @07:44PM (#2928285) Homepage
    != Inhabited planets...

    Recall that a couple of decades ago, Carl Sagan hypothesized that planets that could spawn intelligent life could have equal potential to self destruction to Earth... Chances are, if we manage to visit some of these planets, we'll find some ancient broken down probes, and maybe some nuked out cities, devoid of life...

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