Arecibo Observatory, a 305-meter-wide radio telescope (courtesy of the NAIC – Arecibo Observatory, a facility of the NSF)Owing to radio’s aptitude in transporting information, our planet is endlessly peppered by man-made low-frequency radiation. Phone conversations, computer data, text messages, radar echoes, sitcoms, and morning DJ chatter are all electromagnetically belched in every direction at the speed of light– including straight up into outer space.
Purveyors of science fiction are fond of exploring the ramifications of this radio leakage, suggesting that someday an advanced alien race might materialize to befriend, enslave, or destroy humanity after a little electromagnetic eavesdropping from afar. Indeed, if there happen to be any radio-savvy civilizations within 114 light years of Earth– an area which encompasses roughly fifteen thousand stars– humanity’s earliest meaningful transmissions will have already reached them.
Similar speculation appears in science non-fiction, such as the Search for Extra-Terrestrial Intelligence (SETI) project, which strains its giant radio ears for extraterrestrial signals. When consulting the wisdom of probability, one finds that the universe ought to be teeming with technology-toting aliens; but aside from a couple of interesting-but-inconclusive detections, no discernibly intelligent patterns have ever been observed by Earth’s space-listening instruments. One might surmise that the conspicuous silence is “evidence of absence,” but such a conclusion might be a bit premature under the circumstances.
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