That reminds me .. of one of the problems with SETI.
If you look at how our current civilization uses its large powerful radio broadcast telescopes, they are used mainly for radar imaging—where a powerful one shot pulse is used to image some distant object (such as an asteroid or moon). Naturally there is little point to repeating an imaging pulse.
SETI is designed to search for information carrying signals that are either permanent or repeat reliably, and thus would fail to detect most of the radar energy output for a civilization like our own. Ping-like radar signals are detected all the time by SETI, but they are not the long repeating signals that SETI is looking for.
THIS. It is so incredibly frustrating. The sorts of signals we are likely to see are exactly the ones that are unlikely to be confirmed.
I have the skeleton of a post in my head about the fermi paradox and these sorts of intermediate solutions—what we can observe, and have and have not, what we have excluded and what we have not.
Cool—sounds like a fun post.
At this point SETI can rule out some hypothesis classes—namely those involving colonization of the galaxy by bright hot civilizations. (energy limited stellar based civs)
However, from a pure future engineering perspective, the cold dark model for future civilizations seems more likely on first principles (temperature constrained civs). A galaxy populated by cold dark ET civs would more or less look like what we see now. Perhaps some future clever technique could detect cold dark ETs, but at the moment it seems difficult short of sending out a ton of probes and waiting centuries—probably faster to just create superintelligence on earth and use that to figure it out.
I’ve written a little about the cold dark model and the ‘fermi paradox’ - here.