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Chances of aliens finding Earth disappearing

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  • Chances of aliens finding Earth disappearing

    15:59 09 August 04

    NewScientist.com news service

    A pioneer of the search for extraterrestrial intelligence (SETI) has warned that for any intelligent aliens trying to search for us, "the Earth is going to disappear" very soon.

    Frank Drake's point, made at a SETI workshop at Harvard University on Friday, is that television services are increasingly being delivered by technologies that do not leak radio frequencies into space.

    But he added that in some ways the observation is good news for SETI, as it means that the failure of Earth-based observers to detect aliens so far may be less worrisome than it would otherwise seem.

    Most SETI efforts have focused on detecting radio signals that might be emitted by intelligent beings on planets around nearby stars. For humans, such signals "are the strongest signs of our existence", Drake said, thanks to television.

    Traditional television broadcast antennas put out one megawatt each, and this radio-wave bubble now extends about 50 light years out from the solar system.


    Straight down


    But that is changing fast, Drake says. More and more television is now delivered by cable, with no radio-frequency leakage to space, and by direct-broadcast satellites that put out just 20 watts per channel, all efficiently directed straight down the intended areas on the Earth's surface.

    So from the point of view of being detected through such inadvertent broadcasts, the longevity of humanity's detectability may be just 100 years.

    And longevity may be the most important figure in Drake's famous equation for estimating the number of detectable intelligent civilisations on other worlds. The best estimates show that all the other crucial factors nearly cancel out, so that the number of such civilisations in our Milky Way galaxy is roughly equal to their average longevity of detectability in years.


    Laser beacon


    Drake's insight has important implications for search strategies. It means that eavesdropping on unintended alien transmissions is unlikely to succeed and "argues for an emphasis on detecting beacons", i.e. signals intentionally sent our way.

    Some SETI strategies have already begun shifting toward that approach, including efforts to find optical beacons based on high-powered lasers deliberately aimed at nearby stars.

    While optical communications across interstellar distances was initially thought impractical, military research has led to lasers sufficiently powerful to make such signalling much more efficient than any radio beacon.

    Nuclear-powered lasers on the drawing boards could produce pulses that would outshine the sun by a factor of 10,000, said Harvard University physicist Paul Horowitz, who has already been searching for such pulses. He has designed a new telescope that will soon be dedicated full-time to that search.

    And other innovative ideas keep coming along. Planet hunter Geoffrey Marcy of the University of California, Berkeley, said someday we may learn to use the sun itself as a gravitational-lens telescope, with a detector parked at its focal length of 500 astronomical units.


    David L Chandler



    ...as it means that the failure of Earth-based observers to detect aliens so far may be less worrisome than it would otherwise seem.
    :roll:
    \'You know my destiny?\' said Elric eagerly. \'Tell me what it is, Niun Who Knew All.\'
    Niun opened his mouth as if to speak but then firmly shut it again. \'No,\' he said. \'I have forgotten.\'

  • #2
    Well, to attract more E.T.s we need to send more rock 'n' roll into space!

    We sent some Chuck Berry on Voyager, we gotta start sending some Hawkwind on future probes!
    Madness is always the best armor against Reality

    Comment


    • #3
      I had similar thoughts about SETI (posted on an earlier thread here).

      It wasnt that long ago that we made the first transatlantic radio transmissions, but we leap from that to thinking any advanced civilisation will be broadcasting radio, when it might just be a 200 year phase in our technology.

      SETI might be a bit like people 400 years ago looking for flag signals as a sign of civilsation.

      Comment


      • #4
        have I understoog Drake's theory correctly in that there may only be about 100 civilisations out there (based on the only example of longevity we have).

        that's not very many for the enitre galaxy.

        then again, if their behaviour is anything like human beings, I'm not sue I'd want to make contact. Apologies for the misanthropy, but feeling thoroughly disillusioned today with our species. Ho hum, I'm off to the pub for lunch!

        Comment


        • #5
          Considering that aliens crash landed in the desert of New Mexico in July of 1947, I think they ARE out there and already aware of us. Or even if what crashed in Roswell that day was a "weather balloon" I still think there's enough evidence to conclude that aliens have already been here at some point. Like the great pyramids, the more you look into it the more it seems that the egyptians just didn't have the capability to build them. Or the nasca lines in Peru, why the hell would people back then carve huge images and runways into the ground that can only be seen from the air? Call me crazy, but I think aliens are part of our history that has been lost and forgotten.

          Comment


          • #6
            Originally posted by morphine
            Call me crazy, but I think aliens are part of our history that has been lost and forgotten.
            http://www.thehallofmaat.com/maat/ar...?sid=70&page=1

            I don't think YOU are crazy. But i dislike most theories regarding these phenomenons, considering that they have been hijacked by the
            'lunatic fringe'. It's seems it's more a question of belief rather than evidence. When people who believe in 'The Greys' bring this up at parties et al. They can get really pissed when someone begs to differ.

            Comment


            • #7
              Eatees

              Originally posted by ReaveTheJust
              have I understoog Drake's theory correctly in that there may only be about 100 civilisations out there (based on the only example of longevity we have).

              Drakes theory was a back of a cigarette packet kind of "off the cuff" calculation.Not meant to be anything more than a scientifically informed guess.





              that's not very many for the enitre galaxy.


              They could be standing right next to you, or even be inside you.Technology far advanced is indistinguishable from magic (Clarke's law)!

              then again, if their behaviour is anything like human beings, I'm not sue I'd want to make contact.

              Too late mate, we've been beaming signals into space for donkey's years.All that radio,TV,radar and Lucifer knows what else may be like a signal beacon.


              Apologies for the misanthropy, but feeling thoroughly disillusioned today with our species. Ho hum, I'm off to the pub for lunch!
              Have a pint of iron tetracarbonyl for me please, human!

              Comment

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