Lex, <br>You are on the right path. Your ideas about alternate ways those advanced civilizations may use to communicate with each other is a spot on. They don't use radios. They simply can't. EMW are too slow even for communications inside of our Solar system. This is why all of those SETI (Silly Efforts To Investigate - Stanton Friedman) efforts are doomed. <br>Talking about Drake's equation - he doesn't take in account the fact that advanced civilizations spur to other planets inside and outside of their star systems and establish colonies. As a matter of fact, we are one of them.<br>As per my sources, there are 700+ discovered intelligent civilizations / colonies in a Milky Way alone with at least one known interstellar / interplanetary union.<br>Keep digging this subject and your "IF" and "MAY BE" will become solid "IS".