Re: How long have humans been intelligent enough to be detected by

Hi Kivi,

That's sort of an impossible question to answer !
It depends on how advanced the extraterrestrials are, which is something we don't know. If their technology is just like our own, the answer is that humans can not yet be detected by extraterrestrials. If you took the best equipment currently in use here on Earth, moved it to the nearest star outside our Solar System, and tried to detect life on Earth, you'd fail. We produce a lot of radio waves, and some lights, and so forth, but the distance between the stars is so great that even our best telescopes wouldn't be big enough to detect this accidental "leakage" radiation. Right now humans have no active program to try to signal extraterrestrials, but if we did, and if we used our biggest transmitter (at Arecibo, Puerto Rico), and if we knew where to aim it, and if the estraterrestrials were on one of the 1000 or so closest stars, and if they were looking in the right direction at the right time, and if their technology were similar to our own, then they would be able to detect us.

If you assume that extraterrestrials have much better technology than our own, but still use radio waves, then perhaps the answer would be that we've been "detectable" ever since the radio transmitters (TV and radio stations) became widespread, which is about 50 years, give or take a decade or two.

If you're looking for more information about extraterrestrial intelligence, you can find it on the web or in the library, but you should be careful. There's a lot of complete nonsense out there from people claiming to know all the answers. Be skeptical, and ask yourself if what you read makes sense. A couple of good places to find more are http://www.seti.org and http://seti.planetary.org .

I hope this helps. Please feel free to E-mail me (stevenlevin@we.mediaone.net) if you have more questions about this.