[XorNot]

A truly advanced society might be investing significant effort into making itself detectable to other civilizations though. Any civilization experiencing a substantial post-scarcity phase would be likely to have at least some off-shoot groups which use their substantial resources to engage in this activity.

i.e. if energy was functionally free for the average man (because we had the Dyson swarm up and running or something), then what are the odds that some group wouldn't have used their time to build a transmitter to act as a beacon? Could we even stop them if they wanted to (i.e. even if we didn't want to broadcast locally, sending probes to Alpha Centauri and broadcasting from there would be a good way to conduct intelligence gathering on potential interstellar threats).

[ggm]

We've been broadcasting at quite detectable volume for "contact" (sagan) 100 light- years in a radiating spherical radius. We didn't even have to argue about it.

Beaconing, assumes random dice throw (of who to beacon at) pays off. I'd say the odds are worse than lotto winning: Higher input costs, lower chance of success.

[XorNot]

You don't need to though: directed radio can be switched to point at different targets. In fact this would be preferable: i.e. blinking prime numbers out into the universe could be by switching radio targets to create the message.

[ggm]

Again, you assume that point-source RF which beacons to many places by switching aligns with when they're looking. You have to do a LOT Of hand waving around "better wiser Aliens can listen everywhere all the time" for this to pay off, and I would observe if this is such a brilliant technique, how come we haven't received the beams sent to us?