Also, who knows how long the window would last where a civilization uses electromagnetic waves to communicate, in the ways we would look for them? We've only us

Also, who knows how long the window would last where a civilization uses electromagnetic waves to communicate, in the ways we would look for them? We've only used them for a hundred-plus years or so, maybe in another hundred we will be using something else. That would mean there is only a 200-year period where we emitted detectible radiation, which is only detectible within a certain radius, and the detector would have to be within that radius and listening during that 200-year window at exactly the right distance and time to catch it.