SETI Is 50 Years Old; No Sign of ET

EagleHasLanded writes "The Search for Extraterrestrial Intelligence is 50 years old next month, and still no sign of intelligent alien life. Paul Davies of the Beyond Center (also Chairman of the SETI Post-Detection Taskgroup) says it's time to re-think and expand the search for ET."

Comments

The problem is time

[Todd Knarr]

The problem's basically one of time. Think about this: the first radio transmission on Earth was in 1866. That's 144 years ago. That means that any alien civilization more than 144 light-years away from Earth can't see us in the radio bands. They'd have to be inside the bubble formed by our first radio transmissions to even have a chance of spotting us using the methods SETI does. And that bubble isn't a sphere either, it'll eventually have an inside surface as well as an outer one. We're getting more and more efficient, wasting less and less power beaming radio waves off in all directions. Eventually we'll be broadcasting so little that we won't be detectable at any reasonable distance. Anybody inside that inner surface won't be able to see us either. That'll leave probably a 250-300 light-year thick zone moving steadily outwards that any race looking for us will have to be in to see us by looking for radio transmissions. They won't have to just be looking for us, they'll have to be looking for us during the 3-century period when they're in that zone. Look too early or too late and we're invisible to them.

And the same applies to us: we can look all we want, but if we're not in the radio-transmission zone for another species they'll be invisible to us.

Re:The problem is time

[bill_mcgonigle]

They'd have to be inside the bubble formed by our first radio transmissions to even have a chance of spotting us using the methods SETI does.

No, SETI is looking for intentional beacons, not accidental leakage.

In your terms, our SETI-style space-time bubble is a very very very thin shell from the one (or was it two?) times we actually beamed out a signal. Actually not a shell, because it was directional. Interestingly the small handful of candidate signals fit this pattern.

Personally, I think until we're unafraid enough to light up a real beacon, any more advanced society won't pay us any attention. We're panicky and prone to irrational behavior, which probably makes us uninteresting peers. It seems none of us will live long enough to see humanity get over itself, though perhaps we can push it a bit in that direction.

Re:Patience!

[quisxt]

[citation needed] --cordially, a marine biologist