"Any predatory civilization would probably have detected us by now simply by analyzing our atmosphere, they reason. Humans, Vakoch said, have been using radar,

"Any predatory civilization would probably have detected us by now simply by analyzing our atmosphere, they reason. Humans, Vakoch said, have been using radar, which can purportedly be detected 70 light-years away, since World War II. Television and radio signals would long ago have signaled our presence to malevolent space ruffians, he said." That's how he justifies the broadcasting of signals, but take the next logical step: It also indicates either that nobody is listening, or that they're unable or unwilling to contact us, or that they're already in the process of trying. In any case, it's hard to imagine the METI messages would change anything. By that same argument. And I mean why would the intentional/contrived message be any more persuasive than all our "honest" and un-self-conscious messages to each other over the years? Anybody who was curious could have learned everything by now. I also would like to call out the typical assumption of a "technically-advanced race of aliens" and whatnot. The aliens always seem to be technically advanced, don't they? In other words, like us, but more so. That's a mirror you're looking at, and it's how you recognize something man-made. Homo sapiens is the one with the fetish for techne. It seems the aliens we imagine are always either similar to us (which we like) but better, or else they're dissimilar, and predictably worse/more evil (and tend to look like combinations of creatures from THIS planet that we don't like... insects and reptiles figuring prominently). That's more a mirror of our dislikes, but still a mirror. Aliens are always created in our image, and that shows an embarrassing narcissism & lack of imagination. We're just projecting our hopes & fears. Keep your mind open. One more nitpick: "We won’t know for about 25 years, assuming the communique is sent at the speed of light." Pretty good assumption, given that it's not possible to send EM waves at any other speed!