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.

# posted by Gerry Canavan @ 10:52 PM  |