Quote:
Originally Posted by kennyc
And yes that's the "concerning" part. If you look at the timeline from the beginning of the universe and allow for the time for intelligent species to develop and play that into the distances and power of radio waves and technology to detect weak signals etc. etc. It may not be too unusual that we have not detected anything.
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The time for which a civilization wastefully transmits EM radiation - radio and TV signals - into space is probably very brief. The Earth now is a lot "quieter" in the radio spectrum than it was 20 years ago, since so many more broadcasts are directional satellite transmissions, rather than unidirectional broadcasts, which go off into space.
If our own experience is typical, there may be no more than a 100 year "window" in which a civilization is detectable in radio frequencies; that really is a vanishingly brief interval in the lifetime of a planetary system.