[lloeki]

Over such timescales since you'd aim at another galaxy wholesale you coud bet on Drake equation plus hope a civilisation has survived long enough for a wide enough window to be able to receive the transmission.

> probably wouldn't bother with broadcasting lowly radio waves into the universe.

I bet we would be very glad to receive such a transmission, even when knowing full well "replying" isn't a realistic option (both due to technology limitations and the RTT meaning that even if the reply receives were descendants, they'd be so far removed as to be entirely another ship-of-theseus civilisation)

A gift in a cosmic dying sigh could be motivation enough.

"Should anyone receive this, know that, as far as life forms go, you were not quite alone and life existed beyond yours. We're sending this knowing full well we'll be long gone, but during all of our civilisation history we could only hypothesise that we were not. We hoped but never knew, may this transmission relieve you of the doubts we had; you now unambiguously know."

[usrusr]

At that point you might just as well send out a high power broadcast of Never Gonna Give You Up and congratulate yourself on a job well done, indulging in imaginations of fantastic ways of how it might get received somewhere half a universe lifespan later.