Follow Slashdot blog updates by subscribing to our blog RSS feed

 


Forgot your password?
Close
typodupeerror
×
Space Communications Science

New Telescope Array Goes Live For SETI 159

Posted by Zonk from the hello-is-there-anybody-out-there dept.
The Skinny writes "Today is a historic day for the SETI program. The New York Times reports that astronomers are flipping the switch today on the Allen Telescope Array — 350 antennas, each 20 feet in diameter — which will, among other things, extend the search for extraterrestrial life a thousandfold. From the article: ' There are some 200 billion stars in the galaxy, and a significant fraction of them have planets. Estimates of the number of intelligent civilizations in the galaxy have ranged from one (or none, if you are particularly discouraged about human affairs) into the millions. Dr. Shostak calculated that the full Allen array would be able to detect a signal from as far as 500 light years that is only a few times more powerful than what can now be sent by the Arecibo radio telescope, a 1,000-foot-diameter dish in Puerto Rico that is the world's largest (although it is in danger of being shut down to save money). That translates to about a million stars, which he said was getting into a promising number. Dr. Shostak described the expanded search as looking for the needle in the proverbial haystack with a shovel instead of a spoon.'"
This discussion has been archived. No new comments can be posted.

New Telescope Array Goes Live For SETI More

New Telescope Array Goes Live For SETI

Comments Filter:

  • Only 42 installed so far (Score:4, Informative)

    by Maddog Batty ( 112434 ) on Thursday October 11, 2007 @04:18PM (#20945997) Homepage
    Only 42 installed so far. They are looking for donations to complete the array.
    • How many millions of dollars have they "wasted?" Surely, that money could eve been put to better use. Are they following my president's paradigm with all the funds spent in Iraq?

      • Re: (Score:1, Insightful)

        by ed.mps ( 1015669 )
        IANAS but I think it will, sooner or later, catch some informations that can be useful to non alien-related studies

      • Re:Billions or millions, right? (Score:5, Insightful)

        by theguru ( 70699 ) on Thursday October 11, 2007 @04:34PM (#20946263)
        I always find it amusing when people say money is "wasted". If I took a stack of bill and burned them, or buried them never to be seen again, that would be wasting them.

        If they spent $100mill on a telescope array, where did the money go? It went to some firms who do that, who in turn paid their employees and their suppliers, who paid their employees, etc. Those employees bought groceries, sent their kid to the dentist, sent their kid to college, bought a new car.. the money flowed through the economy. Assuming a large percentage of the firms and suppliers are in this country, then the money stayed in the national economy.

        When the economy is flowing actively, more of those people downstream will be willing to donate their time and money to what you'd probably classify as "good things". When it slows down, or the Government is taking a big chunk at every step as taxes, then they'll be less inclined to do so.

        • What about deflation? (Score:5, Informative)

          by mangu ( 126918 ) on Thursday October 11, 2007 @04:54PM (#20946491)
          If I took a stack of bill and burned them, or buried them never to be seen again, that would be wasting them.


          Although I agree with the rest of your comment, I don't think burning money is wasting it. If you destroy currency you are removing it from circulation, which will cause prices to go down due to deflation.


          If you truly want to waste money, you should buy something of value to others and destroy that thing. The grandfather post would be right, if one assumes that scientific research has no value. However, that is very seldom the case. Research is almost always valuable, even if it turns up nothing. Negative results are also knowledge. If we find no sign of extraterrestrial intelligence in our search we will know more than we did before about the abundance or scarcity of intelligence in our galaxy.

          • The grandfather post would be right, if one assumes that scientific research has no value. However, that is very seldom the case. Research is almost always valuable, even if it turns up nothing. Negative results are also knowledge. If we find no sign of extraterrestrial intelligence in our search we will know more than we did before about the abundance or scarcity of intelligence in our galaxy.

            This is not scientific research. This is more like a lone nomad sifting through the Sahara looking for the Eternal

          • Re: (Score:3, Insightful)

            by 2short ( 466733 )
            "If you destroy currency you are removing it from circulation, which will cause prices to go down due to deflation.

            If you truly want to waste money, you should buy something of value to others and destroy that thing."

            Not at all. Either way, you remove value from the world. Whether in the form of a physical object of a particular value, or in the form of cash (a physical representation of abstract value), your destructive act has the same effect on the wider economy. Which is to say, not much unless it's

            • Re: (Score:2)

              by Copid ( 137416 )

              As far as whether money spent on SETI is "wasted", the point is not whether any good thing (like feeding the builders kids) comes out of it. The point is whether *more* good things would come out of spending that money on some other thing. That same builder could get paid, and feed his kids, building something in support of some more worthy cause. Is there a more worthy cause? Well, I think so, but it isn't my money.

              I think that your last point is the key. There's almost always a more "worthy" cause for

              • Re: (Score:2)

                by 2short ( 466733 )
                Well, I do think SETI is without value. Which does put it above many things we spend money on that actually make life worse for the world at large. But "not evil, just pointless" is not exactly a ringing endorsement. The point of noting that it's not my money is that I won't be protesting in the streets if someone else spends their money on it. I will however, consider them an idiot.

                • Re: (Score:2)

                  by Copid ( 137416 )
                  I assess it similarly to you in that I would be surprised if they actually find the signal that they're looking for, but I also don't see it as totally unlikely that the sheer quantities of raw data that they'll be producing will be useless for other research. Sure, I'd rather see it used on more directed data gathering that could be broadly useful in astronomy, but as I see it, as long as it's producing raw data for somebody to chew on and as long as it's not squeezing out some scarce resource, more power

        • Re:Billions or millions, right? (Score:5, Interesting)

          by Red Flayer ( 890720 ) on Thursday October 11, 2007 @05:02PM (#20946605) Journal
          A couple points to make.

          The first is that there is a concept of 'best-use'. That is, there are some projects (such as SETI) that some people feel are less worthwhile than other projects. Some people believe that the man-hours and capital used on SETI is wasted because nothing of value is produced by SETI (in their opinion) -- so yes, the money flows through the economy, but on a more worthwhile project, that money would flow through the economy while producing something of value. The money is in effect hoarded, which means that the opportunity to use it for growth is wasted.

          The second point has to do with your remark about taxes.

          When the economy is flowing actively, more of those people downstream will be willing to donate their time and money to what you'd probably classify as "good things". When it slows down, or the Government is taking a big chunk at every step as taxes, then they'll be less inclined to do so.
          Money paid as taxes also flows through the economy, for the same reason that money put into erstwhile "wasteful" projects flows through the economy. It's a bit of a double-standard to say that money that goes to taxes inhibits downstream spending, since that money is, in a very real way, redistributed to others, whether by government contract, to government employees, or otherwise. The exceptions would be foreign spending, which generally has benefit to the US as well, if less tangible.

          If anything, with today's government, money taken out as taxes actually produces more money in circulation, since the US government runs a deficit budget with a cap on borrowing based loosely on government receipts. Every $1.00 given to the federal government returns $1.00 * [1 + (annual debt)/(annual receipts) -- of course, that's financed at an as-yet-undetermined final cost, since who knows what interest rate we'll have to pay on it when we refinance through new debt offerings...

          • The first is that there is a concept of 'best-use'. That is, there are some projects (such as SETI) that some people feel are less worthwhile than other projects.

            In economic terms it's called "opportunity cost." The idea being that the cost of something is not just the price, but also the opportunity to use the resources towards something else.
            That is why you can have a business that makes monetary profit, but not economic profit (eg your business makes 3% profit, but you could have earned 4% on a CD)

            • I've learned that using economic terms on slashdot is pretty useless, since most people here have an incomplete or incorrect understanding of the terms. If discussing with someone with an economics background, I'd use terms like opportunity cost... but most of the time I try to use laymans terms here, so that the discussion doesn't get bogged down in corrections of terms usage.

              Prime example of this is how some people on slashdot believe a free market == a market that is free from regulation.

          • Re: (Score:2)

            by tyrione ( 134248 )
            Speaking of the term, 'best use' and what definitely isn't an example: The Iraq Conflict/War/Quagmire, whatever the hell you want to call it. Millions displaced, hate inflated and nothing but a deficit. Some might think it went to "best-use' but I'd rather 100,000 telescope arrays were developed before such a complete and utter waste of time.
        • At the same time, though, I think many people would argue that there is greater social value in spending $100 million on, say, textbooks for underprivileged students than spending $100 million on Internet pornography and rubber chickens. In both cases, the cash will flow through the economy providing benefit, but on the whole, society is likely value one scenario more highly than the other. Of course, this depends on your relative preferences for education, porn, and latex fowl, and I'm not necessarily conv
          • Well maybe SETI will inspire one of those underprivileged students to realise that the reason we can't hear anybody talking out there is because nobody has enough power to talk with and they invent the super-uber powerfull screw-thermodynamics generator and we have so much free power that the 6 billion people in the world all sit arround watch Television, getting fat and having heart attacks when they are not busy behaving badly like Paris Hilton and Britney Spears and talking too fast and running all of th
        • I suggest you brush up on the broken window fallacy (http://en.wikipedia.org/wiki/Parable_of_the_broken_window [wikipedia.org]). Just because money is flowing into the economy does not mean it isn't wasted.

          • Re: (Score:2)

            by theguru ( 70699 )
            I'm familiar with it, but I don't think it applies. It rings true in cases of unexpected, or undesired spending. I wreck my car, I have to pay a body shop. In this case, SETI didn't break their old antenna and have to buy a new one. They chose to. Instead of me wrecking my car, I voluntarily chose to spend the money on a new car, and sell my old one.

            The parable is better applied with the government in the role of the boy, and the public in the role as the shopkeeper. The government takes the public's choice
        • This is also used to talk to Stargate teams without tieing up the Stargate.

        • Re: (Score:2)

          by roystgnr ( 4015 ) *
          If I took a stack of bill and burned them, or buried them never to be seen again, that would be wasting them.

          That would be "wasting money" literally, but it wouldn't be wasting wealth, except insofar as paper money could be used as a scratchy substitute for toilet paper. Imagine if you destroyed 90% of the dollars in the world. Would it be a travesty? Of course not - the remaining 10% of dollars would just be worth 10 times as much.

          If they spent $100mill on a telescope array, where did the money go?

          It pa

        • If they spent $100mill on a telescope array, where did the money go? It went to some firms who do that, who in turn paid their employees and their suppliers, who paid their employees, etc. Those employees bought groceries, sent their kid to the dentist, sent their kid to college, bought a new car.. the money flowed through the economy. Assuming a large percentage of the firms and suppliers are in this country, then the money stayed in the national economy.

          You have confused $100M with $100M worth of resource

        • Re: (Score:2)

          by clambake ( 37702 )
          I always find it amusing when people say money is "wasted". If I took a stack of bill and burned them, or buried them never to be seen again, that would be wasting them.

          What about blowing crap up? i'm curious if the money we spent on the war was wasted or not.

    • At least they got the answer right... (Score:5, Funny)

      by mangu ( 126918 ) on Thursday October 11, 2007 @04:45PM (#20946373)
      42. Why would they need more?

      • Re: (Score:1)

        by ackthpt ( 218170 ) *

        42. Why would they need more?

        Because the 43rd would probably be the one what picks up that crucial signal:

        All your base are belong to us!

        Which would remove all doubt .. there is no intelligent life in outer space.

  • Shovel instead of a spoon? (Score:5, Insightful)

    by moderatorrater ( 1095745 ) on Thursday October 11, 2007 @04:21PM (#20946057)
    I think the better metaphor would be "trying to move a mountain with a spoon instead of a pen cap." Seriously, taking into account the number of stars, the number of planets orbiting the stars, and the span of time that they're likely to be spewing radio waves, the task is monumental compared to any resources that SETI may get. The work is still important, but let's not underestimate the task.

    • Re:Shovel instead of a spoon? (Score:4, Informative)

      by Zymergy ( 803632 ) * on Thursday October 11, 2007 @04:33PM (#20946233)
      Maybe not....
      Study Predicts Trillions Of Planets http://dsc.discovery.com/news/afp/20030922/universe.html [discovery.com]
      NASA estimates the number of terrestrial planets to be as high as 30 Billion: http://astrobiology.arc.nasa.gov/news/expandnews.cfm?id=1227 [nasa.gov]
      (And both articles are several years old...)

    • Seriously, taking into account the number of stars, the number of planets orbiting the stars, and the span of time that they're likely to be spewing radio waves, the task is monumental compared to any resources that SETI may get.

      The number of stars has no effect on the time taken to identify a civilisation. The population density of the galaxy does. It doesn't matter how many stars there are, if every hundredth star system has an earth-like planet, with a life-form that is emitting radio waves, chances a

    • This is an honest question: how is this work important? I really would like to know. Other than providing some work for skilled technical labourers like myself, what do these things do other than point at the sky?
      • Shhh! Speak too loud and you may scare that cat out of its bag.
      • It depends on who you are. If you don't give a shit if there's intelligent life other than us in the universe, then it's not too important. If you're interested in other intelligent life or in exploration for the sake of exploration, then this is what we can do now. I guess it's as important as anything else we do in space.
    • The best way to look for a needle in a haystack is with a magnet. (The worst way would probably be to set fire to the haystack.)
    • I think the first metaphor is perfectly accurate, provided you image the haystack to be the size of the known universe.
  • That's a good name for it!

    • Re: (Score:2)

      by Stanza ( 35421 )

      It's good to know that I'm not the only person to read "Allen Telescope Array" as "Alien Telescope Array".

  • Inverse Square Law (Score:1, Informative)

    by Anonymous Coward
    Inverse Square Law

  • To be honest (Score:2, Insightful)

    by Skiron ( 735617 )
    With 200 billion stars in OUR galaxy alone, and billions of other galaxies in our universe, anybody that thinks we are unique (usually religious type folks) are seriously fooled.

    There has to be hundreds of thousands of life forms out there (at least). The sooner science finds it, the better.
    • Yes but with 200 billion starts in our galaxy alone, how can we hope to find these life forms? Even if we received a signal, the society that generated it would likely have died out billions of years ago.

      • Re: (Score:2, Insightful)

        by Skiron ( 735617 )
        That isn't really relevant. Finding life (that existed) or perhaps still exists removes this silly charade of religion dogma that plagues our the whole world through no other medium than 'belief' and control.

        • Re:To be honest (Score:4, Insightful)

          by UncleTogie ( 1004853 ) * on Thursday October 11, 2007 @05:09PM (#20946699) Homepage Journal

          Finding life (that existed) or perhaps still exists removes this silly charade of religion dogma

          It surely does not. It just puts a different spin on it.

          that plagues our the whole world through no other medium than 'belief' and control.

          Anyone can choose a bad apple and attempt to infer that all apples are bad by it. Doesn't make it any more so...

        • Not really they'll just say the Bible said God created the Earth but it doesn't say he only created the Earth, the Mormons accommodated Turtle Island without too much trouble.

    • Rare Earth (Score:1, Informative)

      by WrongMonkey ( 1027334 )
      There are solid scientific reasons to believe that we are unique. Rare Earth Hypothesis [amazon.com]

    • Re: (Score:2, Interesting)

      by Daimanta ( 1140543 )
      Insert Fermi's paradox:

      http://en.wikipedia.org/wiki/Fermi_paradox [wikipedia.org]

      Tell me, if there is such a ridiculous high chance of other life, where is it? There is not a single clue of extraterrestrial life and this will be a huge moneypit. Well, that and the moonrace.

      • Re: (Score:3, Insightful)

        by Cro Magnon ( 467622 )
        It's a big universe. The odds that extraterrestrial life exists is high. The odds of us finding it in this big universe is not so high.

      • Re: (Score:2)

        by geekoid ( 135745 )
        "Tell me, if there is such a ridiculous high chance of other life, where is it? "

        You are overlooking time.

        Within the time span of the universe, it is certain there are forms of life that had existed but no longer.

        For example, there have been species on this planet that no longer exist.

        So what we could fine is a radio wave that was sent out 1000 years ago...or perhaps some species launched a dive that gives off a regular signal as it just travels across space.

        The moon race has generated a LOT of revenue, tec

      • There is not a single clue of extraterrestrial life and this will be a huge moneypit.

        Well... statistically it's very unlikely that we're alone, but it is possible. However it is infinitely more likely that deciding we must be alone after less than 50 years of research is a little naive.

        I'd rather spend a few percent of the money spend on weaponry on a wasted effort to detect alien life than to turn around in a decade or a century to discover that we're not alone... AND THEY DON'T LIKE US.

      • Re: (Score:2)

        by clambake ( 37702 )
        If the chance is so low that life exists out there in the universe, then that means the chance of US being here is quite low too... and yet, here we are! Which makes you wonder how rare life ACTUALLY is after all.
    • I highly doubt we are unique, or at least that self-replicating beings capable of problem solving are unique to our planet, but the Sagan-esque "billions and billions" argument is not an axiom. Unless and until we find other life, we don't know the actual odds. The probability could very well be lower than the number of atoms in the universe. Maybe intelligent life only pops up once every other universe or so. Maybe this is the first time ever.

      In other words, it is no more foolish to insist that we are

    • Re: (Score:3, Insightful)

      by sidb ( 530400 )
      It doesn't logically follow that, just because we exist, intelligent life is at all likely. It could be so absurdly rare that it would never be likely to happen even once in the life of the universe. The fact that we are here says nothing about the probability of it happening again because we're already a given. It's unintuitive, but it's also basic statistics. There is no solid evidence of how likely life is, just guesses. I wouldn't be surprised to somehow find out that intelligent life is fairly common,

    • With 200 billion stars in OUR galaxy alone, and billions of other galaxies in our universe, anybody that thinks we are unique (usually religious type folks) are seriously fooled. There has to be hundreds of thousands of life forms out there (at least). The sooner science finds it, the better.

      Nonsense. Your claim is as fact free and agenda driven as those whom you deride.

      We simply don't have enough information to evaluate the scarcity or commonality or worlds that will support life. We don't even

    • I agree. UFOs are REAL!!!!!!

      There is, however, no credible evidence supporting its existence of SETI.
    • Unfortunately the only way we seem to be able to look for it right now by attempting to detect radio signals. As others point out, the could mean we have a fairly small window of time to detect an alien civilization. For example, at any point in time we can only detect signals which were sent exactly N years ago from exactly N light years away. If their technology has progressed beyond radio signals 15 years ago, we will only find them if they keep sending out radio transmissions specifically to alert ot

    • Re: (Score:2)

      by 2short ( 466733 )

      Chances that that intelligence exists elsewhere in the universe: near certainty.

      Chances that SETI will find any: pretty small.

      Chances that there is intelligence close enough that we could exchange any communication during the lifetime of one of our species: practically zero.

      "The sooner science finds it, the better."

      Why? What possible benefit in knowing a radio-transmitting culture existed around a star impossibly far away sometime before the rise of dinosaurs?

      SETI has a very small chance to find something

  • See Seth Shostak if you can (Score:3, Informative)

    by G4from128k ( 686170 ) on Thursday October 11, 2007 @04:26PM (#20946143)
    Seth Shostak ( http://en.wikipedia.org/wiki/Seth_Shostak [wikipedia.org] ) is a very entertaining and informative speaker of SETI topcis. See/hear him if you get a chance. He's a fun combo of dry, acerbic, and self-deprecating.
    • Every April the University of Colorado in Boulder convenes a week long World Affairs Conference with luminaries in science, arts, and politics conducting about 300 panels on all kinds of topics. Its free and some people actually plan their vacations to attend this. Seth has been for several years.

  • ...or will the new antenna rollout use the same BOINC client [berkeley.edu] as I'm using now?

    • I can't imagine that you'd need a new client. If this is part of SETI@Home project, I'm sure they'll just make the data from the new array available for the current client to access. I don't know for sure, I'm just guessing, but it makes sense to me...
    • BOINC was designed with the purpose of being a meta client, so if the SETI people are going to make this new stuff under a different BOINC project, all you have to do is add it to your clients, and BOINC will download any necessary processing cores. I don't see why they wouldn't add it to the existing project after a testing phase though.

      • BOINC was designed with the purpose of being a meta client, so if the SETI people are going to make this new stuff under a different BOINC project, all you have to do is add it to your clients, and BOINC will download any necessary processing cores.

        I knew about BOINC being a metaclient, as I also run Einstein@home... Just wasn't sure if they'd count it as a different project or not. I remember the switch from the dedicated SETI client a while back...

        Thanks for the clarification!

    • Re: (Score:2, Interesting)

      by neuron2neuron ( 1080375 )
      Hardly. SETI@home is not 'SETI' - it is one small subgroup of it. If anything, it's more of a publicity stunt than serious science. As i've posted elsewhere, the processing power of SETI@home is dwarfed by a system Harvard retired in 1995, for a more powerfull system. The other problem is that the Aracebo telescope is not the best scope to be using for SETI work. It's not very steerable, it's a fixed dish in a depresion in Puerto Rico - the only aiming that can be done is by moving the receiver (the bit the

      • Re: (Score:3, Informative)

        by SETIGuy ( 33768 ) *

        If Berkley was really serious about SETI, they'd have fitted a META (MillionChannel, Extra-Terrestrial Array - http://seti.harvard.edu/seti/meta.html [harvard.edu]) or a BETA (BillionChannel Extra-Terrestrial Array - http://seti.harvard.edu/seti/setihist.html [harvard.edu]) to process it. It actually takes about as much hardware for a META as is needed for the backend of the BOINC client.

        I think this shows that you have a grave misunderstanding about how SETI@home, SERENDIP, META, and BETA work and how the are very interrelated. I

  • Pfft (Score:2, Informative)

    by neuron2neuron ( 1080375 )
    I wonder if this new publicised technology is better than seti@home, which was eclipsed by the jarvard META array, before it was even launched (the META array could do the job of SETI@home, in real time, and was retired in 1995 for the BETA, which has orders of magnitude more power). As long as SETI is dominated by PR stunts like seti@home, however, it'll never go anywhere

    • Re: (Score:3, Informative)

      by SETIGuy ( 33768 ) *
      I think this shows that you have a grave misunderstanding about how SETI@home, SERENDIP, META, and BETA work and how the are very interrelated. In fact, if you go the the BETA page, you will see "The FFT processor evolved from a design of the Berkeley SETI group."

      SERENDIP, META, and BETA are essentially simple FFT processors, with BETA essentially being four 80 million channel analyzers. That is proof that to an astronomer 240 million is equal to a billion. SERENDIP IV (the last one deployed) was a 168 mi

  • I for one... (Score:3, Funny)

    by Digitus1337 ( 671442 ) <(moc.liamtoh) (ta) (sutigid_kl)> on Thursday October 11, 2007 @04:32PM (#20946225) Homepage
    ...welcome our new alien overlords.

    It's so nice when that meme fits without having to be stretched. This certainly is exciting news (about the telescopes too).
  • having a bunch of small radio telescopes is better than one big one- other than the cost factor.
    • It's called Baseline interferometry. You combine the signals from multiple scopes, to get a scope with the effective size of the distance between them. There have been plans for years to put some in Earth's solar orbit, at various points ahead and behind. this would give a dish that, parallel to the plane of the ecliptic, has an effective size of about 1AU (8 light minutes) radius.

      There are other mutli-telescope arrays, apart from the VLA in New Mexico (made famous by films like Contact) although few are g

    • Re: (Score:3, Informative)

      by ChrisA90278 ( 905188 )
      It's not "a bunch of little telescopes". It is one large phased array. The signals from all the antenna are added in phase. By controlling the delay from each antenna before adding the signals they can point the beam around in the sky. By building more "adders" they can have multiple simultainious beams.

      Think of each dish antenna as an element of a single larger antennta

  • Not just the wrong band, the wrong everything (Score:4, Insightful)

    by Wingsy ( 761354 ) on Thursday October 11, 2007 @04:54PM (#20946485)
    I keep tellin em but they never listen. Aliens gave up on radio eons ago. Poor range, prone to interference, and a host of other disadvantages. If you want to eavesdrop on what's being said about us in the universe, you gots to gets your hands on one of them newfangled SHF gravity wave radios.
    • Maybe the aliens are encrypting their radio transmissions making them indistinguishable from background noise?

      Given the current US wiretap rules, that may not be a bad precaution.
  • Now we can finally use this new device to hack into the galactic internet. I am sure there are some dumb species (like the pakleds) that bought their Wireless Galactic Network Access Point, just plugged it in and left it on the defaults. We need to hook ourselves up with free Galactic Internet Access and then start downloading the Encyclopedia Galactica. Of course our once we start downloading it we better hope the ICFPPC (Intergalactic Copyright Federation for the Protection of Privlidged Content) doe

  • But... lets thing about this logically... (Score:3, Insightful)

    by Rooked_One ( 591287 ) on Thursday October 11, 2007 @05:00PM (#20946595) Journal
    with a spoon, you could easily see the needle... with a shovel of a hay, the needle becomes a little more hard to see.

    Did I mention its not backwards wednesday?

    • Well, then, maybe he should have said, instead of a spoon, it's a hundred spoon-gnomes, each with their own spoon. That would have been not only a better analogy, but amusing as well!

      --Rob

  • SETI is hopeless (Score:4, Insightful)

    by anethema ( 99553 ) on Thursday October 11, 2007 @05:03PM (#20946619) Homepage
    I dont mean to flame but...

    I'm in the EE field, specifically wireless/radio communications.

    The calculation for path loss is:

    Loss dB = 32.44 + 20 log (dist in km) + 20 log (freq in MHz)

    Lets take absolute optimal conditions..proxima centauri is roughly 4 light years away. This is roughly 3.78x10^13 km away. One of the most common frequencies monitored is the "hydrogen line" (1420.40575 MHz) since this is the resonant frequency of hydrogen and is more likely to be used by aliens since we'd most likely be looking there.

    So, lets fill in the equation:

    32.44+ 20log(3.78x10^13)+20log(1420.41)= 367.038 db of loss...

    So lets say they are transmitting with a million watts(90dBm), and there is a 60db dish on both ends(huuge dish)...This gives us a receive level of -157.038dBm. This is a good bit below what any normal radio will receive at. The noise floor is certainly higher than this. Now keep in mind this is the very closest star, which I don't think even has any livable planets.

    Our galaxy is 70-100 thousand light years across and we are right near the edge. So if you take a star not even close to that distance, say 500 light years (still somewhat close on a galactic scale) then the calculations work out to a receive signal of -198dBm. The equipment doesn't exist to pick the signal out of the noise at levels like that.

    God forbid trying to pick the signal out of another galaxy, the nearest being Andromeda. some 2.5 million light years away. Giving Rx signal levels of ~ -273dBm. Safe to say the noise floor is MUCH MUCH higher than this.

    I think SETI is a hopeless pipe dream. That being said, I DO think there is intelligent life out there, probably in our galaxy. There are just too many stars with too many planets to think otherwise.

    • Re: (Score:2)

      by pz ( 113803 )
      Loss dB = 32.44 + 20 log (dist in km) + 20 log (freq in MHz)

      Sorry, I've forgotten 90% of the EM I learned from 20 years ago, but I don't recall that there's a frequency dependence for transmission in vacuum. Is this the right equation to use?
    • Personally I prefer to run the World Community Grid [worldcommunitygrid.org] clients currently searching for drugs for AIDS drugs, Dengue fever and Muscular Dystrophy along with a more general investigation of the Human Proteome [wikipedia.org].

      I feel like SETI is an all or nothing approach at aquiring knowledge - if we are able to receive data from an alien civilisation we could learn far more in a short space of time than from research here on terra firma. It's a gamble and I think maybe we should spread our bets a bit more evenly by shifting CP
    • Don't forget the coincidental timing required for two civilizations to be looking and broadcasting in each other's direction. We cannot listen to them all simultaneously. And if we wanted to be a broadcaster, we certainly couldn't pump jiggiwatt lasers at them all, simultaneously. And if we did, it would only be this decade. That's 10 years out of 14 billion, last count.

      Seti is noble. It's good PR. But it's hopeless and doomed to failure even if the universe is teaming with sentient, space-faring life.

      Our e

    • Re: (Score:2, Informative)

      by AaronParsons ( 1172445 )
      I think you're underestimating the antennas involved here. Arecibo (which is the biggest telescope we've got) has a gain of approximately 140 dB. But the Allan Telescope Array will have a gain only about 10 dB down from that with 42 antennas, and with 350 antennas, it will have a gain of ~170 dB. So if they transmit with an Arecibo, and we listen with a 350 ATA, then Proxima Centauri will come in loud at 30 dBm, and we can see out probably a factor of 100 out past that. It's only a small part of the gal

    • Your calculations are wrong; SETI is viable (Score:5, Interesting)

      by Anonymous Coward on Thursday October 11, 2007 @10:46PM (#20949471)
      "I think SETI is a hopeless pipe dream."
      I assume you think your erroneous application of signal theory leads to that conclusion. More studious and clever people than you have already illustrated the viability of signal reception at these distances, and your analysis is quite simply wrong. Your "EE" expertise has led you astray: when you ask someone who only knows about whales a question about ducks, he talks about whales anyway. Radio astronomy has had these things down for more than 50 years, and you're a day late and a dollar short.

      We're interested in obtaining a signal against a background. The antenna temperature, Ta, determines this:

      Ta = [(pi^2)/16k] * (W/r^2) * (D1^2 * D2^2) / lambda^2
      where
      k is Boltzmann's constant
      W is the power per unit of bandwidth of the source
      D1 and D2 are the diameters of the receiving antenna and (hypothetical) transmitter antenna
      lambda is the wavelength

      The signal, per the common example, is 1420.4GHz => 21.1cm = .211m. The brightness temperature of the galaxy as viewed from Earth's surface is around 5-10 Kelvin at that wavelength.

      What about the noise temperature of the receiver? A receiver must have sufficiently low Tn, otherwise it's louder than the signal it tries to measure:

      Tn-rms = Tn / sqrt(t * Bw)
      where
      Tn-rms is the root-mean-square value in question
      Tn is the noise temperature of the receiver in question
      t is the integration time (how long we keep the lid off the photon bucket)
      Bw is the receiver's bandwidth

      The noise temperature of modern low-noise amplifiers is much lower. A rule of thumb for present-day: 1 Kelvin per GHz, plus 1 Kelvin, so 2~3 Kelvin for this LNA, and there are lower noise devices available for a price, but only to a point. The cosmic background noise is larger than the receiver noise!

      Let's combine them and rearrange, and see just what kinds of power and distance we need:
      r = (pi/4) * sqrt(W / k*Tn) * (D1 * D2 / lambda) * (t * Bw)^.25

      Suppose we have a 50kW transmitter, use the 300m Arecibo dish to transmit and receive, use a bandpass of 1Hz (this is reasonable), and an integration time of about 20 minutes (1,000s). Go ahead; do the math--

      r = (pi/4) * sqrt(50000 / [(1.38e-16)*3] * (300 * 300 / .211) = 4.63*10^18 meters

      Which is 489 light years.
      Yes, given currently manufactured technology, the Arecibo dish could communicate with an identical dish at exactly the distance in the article, given a modest 50kW transmitter. I picked numbers to contrive the distance in question, but all of them are available with current technology, and most of them are already installed and operational at Arecibo Observatory. What if we chose a MW transmitter (available), or halved the wavelength to 10cm, or used a bigger (perhaps virtual) dish, or a lower noise antenna? All of these things would MASSIVELY improve the resolvable range of the transmission. 5000 light years is well within our current technology-limited broadcast/reception range. The hard part, as discussed by others here, is justifying implementing this much hardware and employment (versus buying ONE SINGLE JET FIGHTER).

      If you think the problem with SETI lies in its technical shortcomings, you're sorely mistaken. The SETI program is a long shot for other, more difficult scientific and borderline philosophical reasons, but close examination of the physical problem at hand (which you clearly have not done) illustrates that it's not as long as your cynicism would have you judge in lieu of actual thought. You're welcome to argue your opinions, but don't mis-apply one inapt little corner of signal theory as proof that your perception of the world is, in fact, reality.

      +5 Insightful? The mods have been bamboozled by unfamiliar equations. As for my analysis? Go ahead-- verify it with your favorite relevant textbook, for a change; please.

    • Re: (Score:2)

      by Zoinks ( 20480 )
      You're "in the field," eh? Are you an EE? You learn this stuff in a senior level comm class.

      The "noise floor" (actually noise power spectral density) is determined by kT, Boltzmann constant times Kelvin temperature.

      Looking into empty space, the noise temperature is the magical 3 K. As far as the receiver noise floor, astronomical receivers are typically cryogenically cooled just to reduce the noise floor. So, assuming receiver noise is lower than space noise, the noise PSD is -193.8 dBm/Hz.

      And bandwidth
    • No no no, That equation does not work in a vacuum. The air loss needs something else...namely....air ;) How is it that we can pick up the little tiny signal coming from voyager which went so far beyond us is your equation worked in a vacuum? I guess we would not.
  • They are only using 6 meters wide dishes. Given that they are monitoring 2.4Ghz, this isn't a lot of gain they are getting, even if they inter connect all of the dishes. At least I think I got that correct. But a C-Band system uses large dishes, 2.4Ghz is close to that frequency range (3Ghz).

    Corrections are welcomed.

  • Needles in haystacks (Score:5, Funny)

    by barakn ( 641218 ) on Thursday October 11, 2007 @05:44PM (#20947031)
    Spoons, shovels? I always thought it would be easier to search for a needle in a haystack with a magnet, but what do I know?
  • Hey, if one is going to use a tool to look for a needle in a haystack, I would choose a *magnet*. Consider the amount of radio energy we're spewing into space, we've got a great magnet already. And considering that if there is any other life, it's probably more intelligent then us, the best thing to do is just *wait*. Let's not forget the fact that even if we did discover a radio emenation from 500 light years away, it would take *1000 years* for us to get a response. Surely in 1000 years we'll come up wit

    • Re:Laziness (Score:4, Informative)

      by ChrisA90278 ( 905188 ) on Thursday October 11, 2007 @07:48PM (#20948219)
      They are NOT listening for random signals like the type that are leaked out from Earth. The array is not sensitive enough for that. What they are hoping to find as a beacon. A huge transmitter beamed right at us. If they find such a thing then we might reasonably guess there is a signal on it. We would not have to wait for 2-way communication to learn a lot. Heck even if all we got was a "Hello Earth" greeting that in itself would be one of the greatest discoveries in all of history.

      I doubt there are any huge microwave beacons. If we do discover anyone out there it will only be after our arrays become powerfull enough to hear the "leakage" signals that only escape by chance, like the signals we are currently sending. But we could get lucky. It's like buying a lottery ticket.

  • That's Allen as in Paul Allen, you know.
  • Comment removed based on user account deletion

  • SETI Institute != SETI@home != SETI (Score:4, Informative)

    by SETIGuy ( 33768 ) * on Thursday October 11, 2007 @08:58PM (#20948777) Homepage
    More confusion in the media (and on Slashdot) about just what SETI is. SETI (the Search for Extraterrestrial Intelligence) is a field of study, like physics for example. You wouldn't say "Physics gets a new particle accelerator," would you? It is not a project or a program.

    The SETI Institute is an organization that employs many scientists. A few of the scientists there do SETI (i.e. they search for extraterrestrial intelligence). The vast majority do not. The SETI Institute, in collaboration with the University of California Berkeley, are building a telescope called the Allen Telescope Array. Some of the scientists at the SETI Institute will use it for SETI. Other astronomers will use it for non-SETI related projects.

    SETI@home is a project at the University of California Berkeley. It is neither funded by nor affiliated with the SETI Institute. In fact, some SETI scientists at the SETI Institute, dislike SETI@home because it directs attention (and therefore funding) away from SETI Institute projects. Competing projects also have some at the institute worried that someone else may be the first to detect extraterrestrial intelligence. For those reasons it is unlikely that SETI@home will ever be allowed to utilize data from the Allen Telescope Array.

    From my vantage point, it appears that this confusion is promulgated by the SETI Institute. They would like the world to think that they are in control of all SETI related projects, and they would very much like to control all SETI related funding. At this point they feel that there is no advantage to preventing this confusion. In fact, scientists at the SETI Institute often drop the word "Institute" when they mention their affiliation, and just say they are "from SETI" or "with SETI".

Slashdot Top Deals

Whoever dies with the most toys wins.

Close