Stopping the signal

Does the universe harbour other intelligent lifeforms? According to this NYT article it could do but they may be a whole lot quieter than we first supposed. It makes the point that as older broadcast technology is phased out and replaced by more efficient cable and satellite options we beam less powerful transmissions into space: and if we are getting quieter then it's likely our galactic neighbours are too.

It's perhaps a useful reminder that detecting anything in the wider universe (as well as here on Earth) depends on signals getting through. Scientists are developing some clever tricks to squeeze more information out of these signals - for example gravitational microsensing, recently used to detect two extrasolar planets - but we still rely on 'listening' to the universe. Just as archaeology is not about what was there but what survives, so the search for life is not about what's out there but what reaches us. And of course it may be quiet because there's nobody else out there.