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Space Science

SETI Finds Interesting Signal 816

Posted by michael
from the ding-dong-ditch dept.
Several readers sent in notes about an interesting signal discovered by SETI. No real evidence of Someone Out There, but not fully explainable either. Another reader submits a blurb suggesting that aliens should send spacemail, not signals: "Rutgers electrical engineering professor, Christopher Rose, has an article on Nature magazine's cover today describing the most efficient way for our civilization to be discovered by aliens. On this question of better to 'write or radiate', his conclusions: better not to send radio transmission, when physical media like DNA on an asteroid can declare a terrestrial presence. Similar to what motivated Voyager scientists to attach a plaque for the outbound trip. Rose has some great information payload sizes as examples (like the entire information equivalent for our global genome fitting on a 100 pound laptop!)."
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SETI Finds Interesting Signal

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  • Every time... (Score:5, Interesting)

    by keiferb (267153) on Wednesday September 01, 2004 @07:26PM (#10134111) Homepage
    ...I hear about something like this, I just have to wonder how we know what we're looking for. I mean, seriously... life outside of our solar system is probably not at all like the life we find here on Earth. At least, I sure hope it's not. In any case, how do we even know what to start looking for?
  • Re:DNA Over Signal (Score:5, Interesting)

    by ThisNukes4u (752508) <> on Wednesday September 01, 2004 @07:31PM (#10134141) Homepage
    Well, the problem with radio signals is that they degrade so fast, and the fact that what we transmit will probably not be intelligible to any foreign species, they may get the drift that we are semi-intelligent, but probably not enough information to decipher where we are from or our purpose. With physical artifacts, as long as the beings can see visible light, there is a good chance that they can get a good jist of what we are trying to convey. We can draw pictures of humans and animals and plants on our planet, and possible draw basic symbols and graphs to make out basic mathematical concepts, and possibly the general location of Earth. While it would be much more difficult to locate a physical object than a radio signal, the short range of a radio way probably makes it impractical for long distance communication in space. Of course, there is the possibility of physical objects degrading with time, but with proper materials this should be pretty limited.
  • Is it just me... (Score:3, Interesting)

    by Veridium (752431) on Wednesday September 01, 2004 @07:31PM (#10134144) Homepage
    ...or does hurling an asteroid at a distant planet sound like a good way to piss ETs off? On a more practical note, it also sounds like a good way to infect a planet with some such bug. And if they weren't talking about targeting a planet with that "communication medium", then it seems really absurd that that could be a better way to communicate than radiating. Radiating allows you, with relatively little energy expenditure, to send your message out in many different directions hoping someone gets it. I'm sure someone will correct me if I'm wrong.

    I didn't read any of the articles yet because they all appear to be slashdotted. Nice going everyone.
  • One question (Score:2, Interesting)

    by geneing (756949) on Wednesday September 01, 2004 @07:34PM (#10134179)
    Why do we think that extraterrestrials wouldn't use spread spectrum method for communication? After all it's a more efficient and noise resistant method.

    As I understand, a spread spectrum signal won't appear as a strong peak in fourier space (that's what seti is essentially looking for).

    Any thoughts?

  • by Trespass (225077) on Wednesday September 01, 2004 @07:40PM (#10134223) Homepage
    Any civilization using radio may be using a lot of encrypted digital signals to communicate among themselves. Wouldn't a sufficiently advanced spread spectrum scheme seem like noise?

    Perhaps I am naive, but I think about the things human beings could always see, but couldn't understand until their knowledge progressed past a certain point.
  • by smclean (521851) on Wednesday September 01, 2004 @07:42PM (#10134239) Homepage
    Where's the data? I want to see the signal data. I'm sure it would be confusing to see without the proper perspective and backgrounds into the physics behind their radio telescope and ambient radio noise and whatnot, but I want to look at it anyway.
  • by ArcticCelt (660351) on Wednesday September 01, 2004 @07:52PM (#10134316)
    Ok, now if they can't decipher or get anything out of that signal I think they should made available a file with the data to anyone who want to try to poke and study the thing. They found it with the help of the collectivity so they should give to the collectivity the option of working on it. They should also give the exact coordinates of the signal.
  • Re:One question (Score:5, Interesting)

    by Kiryat Malachi (177258) on Wednesday September 01, 2004 @07:52PM (#10134318) Journal
    Actually, the other problem (probably bigger, even) is that more and more of our communication has gone wireline or low-power line of sight. We're no longer radiating quite as much easily detectable RF, and the SETI guys assume that there's only a finite amount of time where a civilization would unintentionally radiate.

    Basically, I've heard it called the window and door problem - we have a window of 50-100 years (I forget whose estimate) when a civilization is accidentally radiating to find them, and then we have to wait for them to open the door by transmitting intentional beacons.
  • Re:Every time... (Score:3, Interesting)

    by Vesperi (10991) on Wednesday September 01, 2004 @08:17PM (#10134501) Homepage
    The other big thing is water based early evolution favors symmetrical body plans with the mouth at one end and the anus at the other. Intelligence is most frequently found in carnivores, or herbivore descendants of carnivores.

    Also environmental conditions favor body styles. The 'wolf' body form and ecological role has evolved over and over in the placental and marsupial lines.

    Intelligence also favors omnivores that can rapidly move into new areas and are not specialized to any food and can readily adapt to the environment. As soon as humans developed tool use and could make clothing and specialized weapons we could out 'evolve' any other animal because we no longer needed natural selection to factor in to changes.

    So we're likely to find any civilization is going to be derived from symmetrical linier body plan. Number of paired manipulating appendages would be up in the air. As we as sensory, and reproductive organ placements.

  • by gardyloo (512791) on Wednesday September 01, 2004 @08:27PM (#10134568)
    Besides which, if you're the source of some [relatively] monochromatic signal, to account for doppler shifting, you have to know in which direction others will be viewing the signal. If they're above or below your plane of rotation (i.e., on your axis of rotation), there will be a transverse doppler shift, but it won't be modulated (at whatever Hz is mentioned in the article). On the other hand, if they're NOT right on the axis, they'll notice the modulation, but the amount of shift will be dependent on the azimuthal angle, from zero on-axis to maximum at 90 degrees from the axis. Finally, to *properly* account for doppler shifting, you'd have to know from which direction (exactly) the signal will be viewed. If you think it'll be viewed from the other side of whatever you're orbiting, that's a whole 180 deg phase shift in the correction you have to make, compared to the correction you'd make if the viewer were on the line connecting object-orbited --> you --> viewer, in that order. You can "correct", in fact, to the tune of overcorrecting by 2x too much!

    Short version of above: correcting for doppler shift when the viewer's direction is unknown is impossible -- it makes much more sense to NOT correct at all.
  • Re:DNA Over Signal (Score:2, Interesting)

    by Mindragon (627249) * on Wednesday September 01, 2004 @08:38PM (#10134648) Journal
    Well....Considering that we can detect "winks" of planets orbiting other stars from pretty vast distances, why don't we build a giant jupiter-sized mesh that is solar powered and use it to block out or amplify the sunlight at varying intervals?

    It would give new meaning to S...O...S...
  • good idea why?? (Score:3, Interesting)

    by Anonymous Coward on Wednesday September 01, 2004 @08:43PM (#10134694)
    lets talk about israel and palistine..or at least remind people of it. Two groups wanting something the other groups are of the same species from the same planet and yet they fight and kill. Who are the fucking idiots who come to the conclution that any "advanced" civilization will automaticaly be peaceful and nice and like us just the way we are. This is obsured. There is no correlation between aliens being avanced = nice and fuzzy. We should not be sending signals in any form telling the universe who we are and where we live....listening might be a good idea. Hell that might be the reason we havn't found anything yet....the aliens don't want to advertise their presence becouse what might find them might not be so nice.

    If any "advanced" alien culture finds us I for one am hoping that we have nothing they want.
  • Re:Every time... (Score:5, Interesting)

    by Snocone (158524) on Wednesday September 01, 2004 @09:02PM (#10134835) Homepage
    The first assumption I make is that it has to be water-based organic life. It has to be water...

    Not necessarily. On a somewhat cooler world than ours with 4-5% flourine in the atmosphere, water would be immediately broken down into oxygen and hydroflouric acid, which is liquid in the -83 to 19.4 C range.

    This works because "plants" could function by photosynthesis with HF in place of water and carbon tetraflouride in place of carbon dioxide to produce H-C-F chain compounds and liberate free flourine, with nickel as the catalyst in place of the magnesium in chlorophyll. We'd have to postulate higher UV energy levels as well to provide enough decomposition energy, but that goes along with a thinner atmosphere and lower temperatures without much of a stretch.

    "Animal" soft tissues in this scenario would be about the same as the plants, but hard tissues would be produced by the reaction

    { H-C-F } + F2 -> { F-C-F } + HF

    resulting in a teflon boned and shelled organism, probably one muther-tough sonofabitch. His main energy reaction would be

    { H-C-F } + F2 -> CF4 + HF

    with a blood catalyst metal of titanium, which would result in colorless arterial blood and violet veinous, as the titanium flips back and forth between tri- and tetra-valent states. So he'd probably be a good deal more energetic than us 02-running organisms as well.

    Given what we know about vulcanism on the outer moons and so forth, I wouldn't be surprised to find that a scenario along these lines is rather more probable around the universe than the local one we're familiar with.

    Their technology would be rather different than ours too, since no terrestial style organic matter is possible, and there wouldn't be much around except flourides; no oxides, sulfides, silicates, or chlorides. All metallurgy would have to be electrical. Oh, and they probably wouldn't be good mountain climbers either, since flourides are structurally weak; nothing tough like granite to make mountains out of. So technological progress seems a trifle unlikely. But *shrug* they'd probably think that about Earth, too...
  • Re:Power supply (Score:2, Interesting)

    by cot (87677) on Wednesday September 01, 2004 @09:07PM (#10134865)
    Keep in mind that radio transmissions from the earth fall off as 1/R^2, so as the probe gets very distant from the earth, the probe's signal will be significantly stronger for the local area at even a low power. A radiostation typically goes at 50kW or so I believe. Even a meager 1-10W transmitter on a probe would vastly outshine that radio station to the local area around it once it's outside the solar system.

    the probe could be programmed to start transmitting whenever it got power to its solar cells and keep going until the power's gone. At least it would be talking whenever it's near another star
  • Re:DNA Over Signal (Score:1, Interesting)

    by Anonymous Coward on Wednesday September 01, 2004 @09:17PM (#10134928)
    The range of the electromagnetic force may NOT be infinite. (The range of a photon is, however; I'll explain below).

    Between two electrons, A and B, there exists a repulsive force that reduces in strength by the 1/r^2 ratio we all know and love.

    The repulsive force is described as an exchange of a virtual photon between the two. The virtual photon has a mass/engery associated with it, such that it cannot be more than A+B's rest mass/energy (violation of law of conservation). The closer the particles, the closer the virtual photon's rest/mass energy is to A+B, and the stronger the force is. The further away, the weaker it is.

    The problem is that energy is quantized. At some distance r, the rest mass/energy of the virtual photon is less than plank mass. Since plank mass is the smallest possible mass, anything less is zero. Zero = it doesn't exist!

    (Note I say mass/energy in terms of the massless photon to note that it still has energy due to E=mc2 yada yada)

    IIRC the calculated range of EM between two isolated electrons is roughly the size of the milkyway, so it's not as big as you'd think!

    This also has only to do with the EM component of a particle. A photon itself has infinite range. Two particles however cannot "feel" each other over infinite range as it would require a virtual particle with less energy than plank mass/energy.

  • by Long-EZ (755920) on Wednesday September 01, 2004 @09:33PM (#10135022)

    Disclaimer: I am not a SETI scientist, but I play one on my home computer [].

    Named SHGb02+14a, the possible alien communication has a frequency of about 1420 megahertz - one of the main frequencies at which hydrogen, the most common element in the universe, readily absorbs and emits energy.

    If the signal was some multiple of a prominent hydrogen line, I'd be more inclined to think it's ET. The hydrogen line would be a universally understood reference frequency, and a frequency that is a multiple of that frequency by a factor of 2, 3 or pi would be a frequency that wouldn't have a lot of naturally occurring interference. When the signal is the prominent hydrogen emission line, it seems a lot more likely that this is a previously unknown natural phenomenon. Some hydrogen out there is being excited by some form of naturally occurring energy. That's still not a bad discovery, and is a good example of the surrendipity that's always been at work in science, and it shows that SETI is doing *real* science, despite what SETI's detractors might argue.

    The unexplained signal appears to be emanating from a point between the constellations of Pisces and Aries, where there is no obvious star or planetary system within 1,000 light years, and the transmission is also very faint.

    That seems a bit suspicious too. It would require an enormous amount of power to broadcast a signal we could detect over that large distance. Wishing doesn't make these things true, but I'd certainly prefer a signal from a closer neighbor, so we could have a meaningful conversation.

    So far, the telescope has managed to pick up the signal for only about a minute in total, which is not sufficient for astronomers to analyse it fully.

    That's the problem with a fixed dish. It points where it points, and it moves as the Earth rotates. SETI gets "leftover" time on Arecibo, making it difficult to do the research they'd like to do. That should change soon when SETI has access to their new large array of dishes forming an interferometer that they can point where they want, and dwell on an area for a much longer period of time. Paul Allen may have been instrumental in creating the evil Microsoft empire (see how I worked in the mandatory /. anti-MS bias?), but he's provided adequate contrition for that sin by funding Scaled Composite's X-Prize hardware and the SETI interferometer. What a dude.

    Other questions arise over the signal's frequency, which oscillates by between eight and 37 hertz a second. Paul Horowitz, a Harvard University astronomer who looks for alien signals using optical telescopes, believes that the drift in the signal makes it "fishy".

    OK. He's an optical guy. But he's never heard of Frequency Modulation (FM radio)?

    Assuming it's a natural phenomenon, this might be Doppler shift? I don't know how quickly the frequency drifts, but large planets have been observed close to stars with orbital periods of a couple of days. With weird objects like black holes and neutron stars, which definitely have the power to produce signals we could detect from that far away, who knows what type of weird celestial mechanics might be involved?

    This unexplained phenomenon has now attracted the attention of radio astronomers. It'll get the instrument time required to collect a lot more data, and we'll probably learn what's causing this signal fairly soon. Man, ya' gotta' love science.

  • by Psychofreak (17440) on Wednesday September 01, 2004 @10:17PM (#10135194) Journal
    OK, one of the articles states that the "Break Even Point" for sending energy vs physical data is around 10^14 bits of data. With this in mind, and text being ASCII as 7 bit, or binary as 8 bit (easier math for me at least) that is 1.25x10^13 charcters. Lets assume a 5 charcter average word ( I know this is slightly small, six and a half is probably better, but close, again easy math.) This gives 2.5x10^12 words that can be used. If I remember my History and english classes (been a few years) a typical page is around 300 to 500 words. Again, lets be easy with the math and use 500. This gives 5x10^9 pages of info. I remember most of my textbooks cecking in at around 1500 pages so we have a whole library (3.33x10^6) of books that can be transmitted toa location for the approximate price of shipping those books. How about we choose a few good texts that explain our learning and run with that. The data needed to convey intelligence and civilizatin is much less than a whole library.
    On the other hand without a whole library to sift though who is going to make sure the picture is fair and balanced... lets touch that when they are ready to visit.

    Hope this picture helps a bit
  • Re:DNA Over Signal (Score:4, Interesting)

    by morcheeba (260908) * on Wednesday September 01, 2004 @11:53PM (#10135713) Journal
    The modulation would just have to be very slow so they don't integrate the whole modulation over the "staring" period.

    Excellent point, but not necessarily true. Sure, you'd need a long integration time, but that doesn't mean that the code rate would have to be slow. If the signal is periodic (and it'll be hard to be noticed unless it is), you or the aliens can integrate bits from different cycles. That's assuming that the receiver knows the period, but with enough compute power, they can try all possible periods.

    The Arecibo bit rate is 10 per second -- much faster than most deep space star exposures, but decipherable with the above method.
  • by Bora Horza Gobuchol (585774) on Thursday September 02, 2004 @12:24AM (#10135869)

    This is really, really exciting. I can think of several possible reasons for the anomalies found in the signal thus far. I'm also aware I'm twisting the facts to fit a theory.

    The signal originates where there is "no known star system". Of course. You (advanced alien culture) place the radio source outside your own system, for several reasons - so that the signal won't be confused with a natural source (pulsar, etc); so it won't interfere with radio reception on your own planet; and (for those of an especially paranoid bent) so that if anyone does try to physically investigate the source of the signal, they're not lead directly to your home planet. Instead, set a "tripwire" up on the device - if it's disturbed, send a signal back to the home planet (a scenario explored in Clarke's short story "The Sentinel", which became the basis for "2001").

    The frequency is wavering? Of course! Set the signal to repeat over as broad a frequency range as possible, to attract as much attention as possible - not everyone will be looking at the "waterhole".

    Did I mention I was excited?

  • Re:good idea why?? (Score:3, Interesting)

    by Schwarzchild (225794) on Thursday September 02, 2004 @12:35AM (#10135921)
    Mod parent up. He has a good point.

    If we do find an advanced alien civilization then they may merely decide that we are a violent race and decide to exterminate us for their own safety on the other hand if we were to find an alien race that was technologically inferior to us then no doubt some country or some people would either try to destroy them or abuse them because they could.

    Consider how many wars are ongoing right here on Earth right now. There is no reason why we would necessarily have peaceful relations with aliens.

  • by artao (648799) on Thursday September 02, 2004 @12:38AM (#10135923) Journal
    Just now, listening to Coast to Coast with George Noory (formerly Art Bell), he had Seth Shostak of the SETI Institute on discussing this story. He said, basically, that the reporter (at NewScientist) was kinda lookin for a story, so he found one, if you know what I mean.
    Mr.(Dr.?)Shostak said the first he heard of this was within the last couple days, and when he contacted the SETI@Home folks(which is NOT part of the SETI Institute, but they certainly have a working relationship) to find out what was going on, they also weren't really sure what the hoopla was about.
    Apparently the reporter didn't fully understand the intricacies of the signal hunt, if you will, and got WOWed by a marginal-to-non wow.
    Oh well. But if Coast to Coast isn't buying it ...

    sorry to burst the bubble. i'm disappointed, too.
  • Re:Every time... (Score:4, Interesting)

    by deglr6328 (150198) on Thursday September 02, 2004 @12:49AM (#10135981)
    I'm afraid can't see how this would work. In an atmosphere of HF and F2 how could reaction catalyzing complex molecules ever exist for more than a few seconds, they would be broken down and oxidized very quickly, rendering them useless. Fluorine is just too hungry for electrons! :) Also the HF would quickly dissolve various minerals etc. and form insoluble salts thereby sequestering all the F out of the atmosphere and into the lithosphere in solid bonded form in a short (geological) time period.
  • by Lord Bitman (95493) on Thursday September 02, 2004 @12:50AM (#10135986) Homepage
    Any civilization which has survived long enough to get to Earth and kick our monkey asses has probably figured out enough that they dont need to exploit anybody. And even if they did, they'd probably wait until we got over our pesky nuclear weapon phase- no point in stealing an irradiated planet.
    Of course, if they don't have FTL travel, they may just be patient enough to wait out a little radiation.
  • by MobyTurbo (537363) on Thursday September 02, 2004 @12:58AM (#10136020) Homepage
    What I really want to live to see is how the world's religions suddenly reinvent their "sacred history" to deal with proof of the existence of intelligent alien life. My ideal scenario would be:

    - they're much more advanced that we are
    - they couldn't give a stuff about us, either way

    That would give many established religions a big PR problem.

    Well, I recall reading an essay from an Orthodox Jewish Rabbi. Essentially he said that unless the aliens claimed to be Jews, there's no theological problem.
  • Re:DNA Over Signal (Score:5, Interesting)

    by Christopher Thomas (11717) on Thursday September 02, 2004 @01:02AM (#10136032)
    Its not a problem of the actual signals degrading.

    They get completely overpowered by the huge great big solar radio emitter, so that by the time they reach another starsystem, all thats resolvable is the signal from our sun itself.

    This actually turns out not to be the case, for a couple of reasons. First, Earth outshines the sun on several radio bands - the sun's dumping most of its energy as visible light, and while electrical effects in its atmosphere are noisy, they don't cover the entire radio spectrum. Second, we could launch solar-orbit radio telescope arrays _now_ that would have enough angular resolution to pick out individual thunderstorms on the superjovian planets we've detected nearby. Resolving a beacon from a star spatially, for any star system near enough to matter, is do-able (though we aren't going to do it ourselves until we decide a space-based radio telescope array is worth the money).

    I also question the parent post's assertations that radio signals are degraded to unintelligability. We can pick up millisecond pulsars just fine, meaning we could at the very least broadcast a beacon with data modulated at kHz rates. My understanding is that there are relatively clean frequency windows in the interstellar medium that would let us transmit intelligeably at far higher bandwidth.
  • by Christopher Thomas (11717) on Thursday September 02, 2004 @01:23AM (#10136146)
    See, that's my problem. I'd like to go with your EM theory of communication, but I can't find any way of telling whether it's biased. So, how can I tell if what I've picked is subject to bias or not?

    Please spell out how! That's all I'm asking.

    The "can't possibly be biased" element from my original post was the frequency of the light being transmitted, not the use of EM in the first place. Hydrogen emission lines are fundamental constants of nature (at least in our neck of the woods; ObCaveats about very, very distant parts of the universe possibly having different values for these constants). Choosing a blatant derivative of one would be an unambiguous way of saying "look, I'm intelligent!" that is not tainted by human biases (except in the definition of "intelligence").

    The argument for EM is that we seem to understand virtually all of the observable universe now, unlike your proposed witchcraft-using primitives, and EM looks like the _only_ choice for long-distance communication. The only possible objection is that we can't be sure that we understand the universe well enough to label alternate communications modes "unlikely".

    I consider it likely that we understand the universe well enough to do this, as the relevant bits of physical theory have been around arguably even since Newton's day, and have stood despite very aggressive challenging (new models are best viewed as extending, not overturning, old, as they tend to reduce to the old models in the old models' domains of applicability). Your opinion may vary (and apparently does).
  • by RedLaggedTeut (216304) on Thursday September 02, 2004 @02:36AM (#10136410) Homepage Journal
    Why not mix the suggestions and have a spaceship with an ion drive that has a transmitter which can be aimed at the closest star ?

    You wouldn't need to correct trajectory much, since you'd just be aiming at getting away from your earth and you would reduce the transmission power requirements.

    Might explain why the signal found by S.E.T.I. is coming from nowhere. You'd have to check the parallax shift to determine the actual signal distance.

    I'd have no explanation for the shift in frequency though, if it came from a spacecraft.
    Maybe the data is in the change of frequency, not intensity, or frequency is intentionally shifted to make the signal noticably by planets that rotate themselves.
  • by Minna Kirai (624281) on Thursday September 02, 2004 @02:54AM (#10136470)
    I'd like to go with your EM theory of communication,

    The progress of science has gradually reduced the number of entities/objects/forces required to explain all existence. If you don't think electromagnetism is appropriate, then there are exactly two other choices: gravity or "strong" (atomic cohesion bonds, aka physical matter).

    Of the 3 fundamental forces, EM seems the best way to communicate.

    So, how can I tell if what I've picked is subject to bias or not? Please spell out how! That's all I'm asking.

    How do you know that you're not completely insane, and everything you see around you is a delusion?

    Questions of that form cannot be answered, but it doesn't matter. If you're right you're right, and if you're wrong, you have no way of ever knowing. If our knowledge of physics is so far off as to be missing something so important it could be used for communication (quantum telepathy waves?), then there's no hope for us.
  • Re:Waste of time (Score:2, Interesting)

    by 1arkhaine (671283) <<moc.liamg> <ta> <rehellek.naimad>> on Thursday September 02, 2004 @03:02AM (#10136483) Homepage
    Of course, St Thomas *does* owe this 're-discovering' to the Arabs, who for centuries were the only people studying Aristotle - and a few other Greeks, also even Plotinus! John the Scot (an Irishman) was also familiar with the man's work, probably through the Arab's, although not much is known about all that, and he was around in the 9th century.
  • by jez9999 (618189) on Thursday September 02, 2004 @04:45AM (#10136820) Homepage Journal
    This inspires confidence that our current understanding of reality is correct, at least for the domains where the models are intended to apply (important caveat).

    Indeed it is - and doesn't it apply here? If EM signals take hundreds of years to reach us from nearby stars, don't you think aliens wouldn't even bother trying to send them out, realising how pointless a means of interstellar communications these signals are? They're likely to be either working on a more appropriate/speedy technology for communications or have already developed it, and we don't have a clue how to pick it up.
  • Re:DNA Over Signal (Score:3, Interesting)

    by Idarubicin (579475) <allsquiet@hotm a i l .com> on Thursday September 02, 2004 @08:30AM (#10137914) Journal
    It's a moot point--you can indeed throw your hundred rocks out towards the nearest stars, or towards the stars that you feel are most likely to be life-bearing, or whatever.

    On the other hand, you can also focus your radio transmission. The inverse square law only applies if you are emitting in all directions. If you send a relatively well collimated beam out from Aricebo, you're going to have a very well-behaved signal that you can detect a long way off. Indeed, this was done decades ago.

    The chief advantage of throwing rocks is that it requires no maintenance at this end. If you want to use a radio beacon, then you have to maintain it for as long as you want to transmit, and you're limited quite a bit in terms of the number of targets you can point to with each dish. Meanwhile, radio signals will get to your target a lot faster (whether this is a good thing or not is open to discussion) and are probably easier to detect than a rock.

  • Figures (Score:3, Interesting)

    by CBob (722532) <> on Thursday September 02, 2004 @08:45AM (#10138077)
    I just dropped SETI about a month ago after 2k workunits and one candidate.

    I got tired of the information void that they were presenting on server/app status when rolling out BOINC. They got numerous offers from a range of supportive folks from students to users to faculty at OTHER colleges to keep the web page up to date and ignored them.

    The newsgroups that allegedly supported the project looked like text book examples of bad usenet w/the flaming and "screw you, you're a volunteer" msgs. The user/support forums on the website were seemingly user run w/little input from the project as well.

    After losing my old my-deja email and credit for those units and all this warm fuzzy support, I decided to take my CPU cycles elsewhere.

    (and bask in the glory of being ignored there too no doubt)
  • by Oligonicella (659917) on Thursday September 02, 2004 @09:02AM (#10138266)
    That depends. If they are posting "beacons" for others to see, they probably (intelligently) would shoot for the largest audience. These beacons wouldn't use the transmission medium of the "advanced" messages, just provide a way of focusing attention in the appropriate area. Then, those who found those beacons could winnow down as far as their technologies allowed them.

    Kind of a self-limiting process on who who want to communicate with on what level, as well.
  • Re:DNA Over Signal (Score:3, Interesting)

    by julesh (229690) on Thursday September 02, 2004 @12:47PM (#10141101)
    Huh? Who says you have to fling them out in an even distribution? Why not send those 100 rocks out towards the 100 nearest stars?

    Well, why not use a focused EM signal pointed toward the 100 nearest stars? Exactly the same argument applies. If you focus it tightly enough you will lose very little power.

    Your rocks, by the way, will either make it or not make it (perhaps because they crash into something else orbiting the destination star before they're noticed). Admittedly, the star's gravity means you have a large target to aim for.

The most exciting phrase to hear in science, the one that heralds new discoveries, is not "Eureka!" (I found it!) but "That's funny ..." -- Isaac Asimov