to bring a little bit Action here
Is life common in the universe? Biologists today tend to think so.
Are intelligent, technological species of life ? like us ? common or long-lasting? No one knows, and the best scientific opinions are sharply divided.
Are any such civilizations broadcasting their existence to the cosmos? There's only one way to find out, and that's to listen.
Several large searches for extraterrestrial intelligence (SETI) are currently scanning the stars, looking for both radio and laser transmissions from distant civilizations. Either type of signal could be sent across interstellar distances fairly economically, scientists are convinced.
Radio searches have been going on the longest, and the theory behind them is well established. All radio searches follow the same basic strategy: they hunt through the microwave part of the spectrum for any extremely narrowband (single-frequency) signal coming from outside the solar system. According to conventional wisdom, this is the kind of broadcast that has the best chance of being detected across interstellar distances.
Of the entire radio spectrum, the band of frequencies from about 0.5 to 60 gigahertz has the least natural background interference in space. Any alien radio astronomers should realize this too ? and perhaps they would build interstellar transmitters accordingly. Our atmosphere tends to limit us to frequencies below about 12 gigahertz, but maybe other civilizations would have reason to choose the low end of the frequency range too.
Full Story
Sir Ulli
Is life common in the universe? Biologists today tend to think so.
Are intelligent, technological species of life ? like us ? common or long-lasting? No one knows, and the best scientific opinions are sharply divided.
Are any such civilizations broadcasting their existence to the cosmos? There's only one way to find out, and that's to listen.
Several large searches for extraterrestrial intelligence (SETI) are currently scanning the stars, looking for both radio and laser transmissions from distant civilizations. Either type of signal could be sent across interstellar distances fairly economically, scientists are convinced.
Radio searches have been going on the longest, and the theory behind them is well established. All radio searches follow the same basic strategy: they hunt through the microwave part of the spectrum for any extremely narrowband (single-frequency) signal coming from outside the solar system. According to conventional wisdom, this is the kind of broadcast that has the best chance of being detected across interstellar distances.
Of the entire radio spectrum, the band of frequencies from about 0.5 to 60 gigahertz has the least natural background interference in space. Any alien radio astronomers should realize this too ? and perhaps they would build interstellar transmitters accordingly. Our atmosphere tends to limit us to frequencies below about 12 gigahertz, but maybe other civilizations would have reason to choose the low end of the frequency range too.
Full Story
Sir Ulli
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