As the world of wireless communication gets bigger and bigger, the signals are getting smaller and smaller. We are cramming millions of devices in a small area and by necessity we are using Uber Wideband QAM-16384 Mulipathing Spread Spectrum (OK, that isn't a real modulation form, but it will be next week, and then it will be obsolete the week after that).
The point I am trying to make is as population density and technology reach a peak, the "radio sphere" our planet is emitting is eventually going to be undetectable. AM radio and other broadcasting will eventually cease to be. Broadcasting will still be around, it is just going to be directed at individual devices. This really isn't going to take a long time to happen. Even the poor 3rd world contries will eventually progress, they will be forced to from population density. 100 years would be VERY conservative. This will give our planet a detectable radio spere less than 300 light years wide. RF emitted from the Earth will soon be indistinguishable noise especially when compared to all the other cosmic radiation.
We can assume any Extra Terrestrial Intelligence that has entered the wireless era will take the same path if their population density increases enough and they have the technology to match.
It will be like trying to find your lost kid in Disneyland. Your brat was at the Haunted Mansion 20 minutes ago, but by the time you get there, he has already moved on to It's a Small World. It is quite likely that our radio sphere will never cross another planet's during an era in which it is able to detect it. The aliens would have the same problem trying to detect us. If they miss the 300 light year or so window (extremely short in cosmic terms), they will never know we are here by listening to whatever version of SETI they are running.
The bottom line is we not only need to keep listening, but we need to direct high power AM and CW transmissions out into space for as long as we can.
The point I am trying to make is as population density and technology reach a peak, the "radio sphere" our planet is emitting is eventually going to be undetectable. AM radio and other broadcasting will eventually cease to be. Broadcasting will still be around, it is just going to be directed at individual devices. This really isn't going to take a long time to happen. Even the poor 3rd world contries will eventually progress, they will be forced to from population density. 100 years would be VERY conservative. This will give our planet a detectable radio spere less than 300 light years wide. RF emitted from the Earth will soon be indistinguishable noise especially when compared to all the other cosmic radiation.
We can assume any Extra Terrestrial Intelligence that has entered the wireless era will take the same path if their population density increases enough and they have the technology to match.
It will be like trying to find your lost kid in Disneyland. Your brat was at the Haunted Mansion 20 minutes ago, but by the time you get there, he has already moved on to It's a Small World. It is quite likely that our radio sphere will never cross another planet's during an era in which it is able to detect it. The aliens would have the same problem trying to detect us. If they miss the 300 light year or so window (extremely short in cosmic terms), they will never know we are here by listening to whatever version of SETI they are running.
The bottom line is we not only need to keep listening, but we need to direct high power AM and CW transmissions out into space for as long as we can.