04-17-2015, 06:05 PM
We do leave the lights on- that is part of the problem.
A lot of people talk about the undetectability of our own civilisation - how our radio and TV signals would be undetectable at a light-year range and so on. They seem to forget that this assumes that they aliens are using detectors comparable to the ones we have already built. It is not unreasonable to assume that an advanced civilisation might have built detectors that are more sensitive by many orders of magnitude. If they can't detect our radio wavelength transmissions then they could detect the lights from our cities using sufficiently large optical telescopes. In short- in there is an advanced civilisation anywhere within a thousand light year range they could (eventually) detect us - we don't need to send out METI or active SETI messages.
A lot of people talk about the undetectability of our own civilisation - how our radio and TV signals would be undetectable at a light-year range and so on. They seem to forget that this assumes that they aliens are using detectors comparable to the ones we have already built. It is not unreasonable to assume that an advanced civilisation might have built detectors that are more sensitive by many orders of magnitude. If they can't detect our radio wavelength transmissions then they could detect the lights from our cities using sufficiently large optical telescopes. In short- in there is an advanced civilisation anywhere within a thousand light year range they could (eventually) detect us - we don't need to send out METI or active SETI messages.