[analog31]

I think we're quickly moving towards living in a sort of poor man's Dyson sphere. More and more of our communications are being enclosed in optical fibers that leak virtually no radiation. Our free space comms are increasingly designed to operate on diminishing amounts of power, and to be practically indistinguishable from noise. We may be a dark planet by a couple centuries from the invention of radio.

Chemical changes to our atmosphere might be detectable from afar.