- I consider these initiatives inexcusably reckless. It may well be that their most likely outcome is that the messages never reach any extraterrestrials - either because the extraterrestrials do not exist, or because our messages remain needles in the cosmic haystack - but if they do, it could well be terribly dangerous. Both in classical SETI [Search for Extraterrestrial Intelligence] and in METI, there is a more or less explicit assumption that extraterrestrials are friendly. But how do we know that? What if there are civilizations (one or more) out there with the capacity for interstellar travel and the policy of preemptively wiping out newcomers? [...]
I'm not saying METI will always be the wrong way to go, just that we currently know too little to go ahead with it. [...]
A common response to fears about METI signals informing hostile aliens about our existence is that they already know about us, because of detectable leakage of our more everyday radio and radar activities, artificial night-time lighting of large urban areas, or the anomalously rapid changes in the composition of our atmosphere. (See Haqq-Misra et al. (2013) for a survey of such considerations.) Settling this issue is far from straightforward, because detectability of Earth-originating signals depends on signal strength, on distance, and on the size of the aliens' telescopes. But suppose, for the sake of argument, that METI signaling does not impose any added risk of aliens detecting our existence, above and beyond what our other activities reveal. What, then, is the point of METI? Or, as Brin (2014) asks "If the horses are gone, why are they so eager to open the barn door?", to which he adds that this exposes the hypocricy of METI advocates. To which I agree.