Chris Peterson wrote:Ann wrote:Like Owlice said, we can never prove a negative - that is, if we don't find anything at all, that doesn't prove much at all - so we can go on searching and searching and searching pretty much indefinitely without finding anything, and still say that we should go on searching.
An important, and often overlooked aspect of science, is that proof is not a requirement. The longer we search, and the more approaches we use (different frequencies, different sensitivities, different search protocols), the more information we have. That is, we don't just have a single piece of information, "no life detected", but we can have a lot of data which places constraints on what might be out there. For instance, we might say with near certainty that we know that there is no intelligent life on Star X which is using unfocused radio with a given power level and a given spectrum.
Suppose there are intelligent beings on a planet orbiting a star ten light-years away. Let us suppose that like us, they are not deliberately sending signals into space to draw attention to themselves, but like us, they are using a kind of SETI system to listen for signals from others. Coincidentally enough, their SETI system is incredibly similar to ours, with pretty much exactly the same capability of detecting signals.
Would they hear us?
If not, would they "almost hear us", or wouldn't they even come close to hearing us?
In other words, if there was a civilisation similar to ours ten light-years away, a civilisation that is not deliberately sending signals into space to call attention to themselves, what chances would we have to hear them?
Ann