How Do We Know If There’s a Message?
As we have seen, radio waves can be excellent candidates for interplanetary communication, due to the fact that our galaxy is transparent to them. The problem lies in properly identifying the origin – artificial or natural – of an arriving signal. When we tune a radio receiver and we turn the antenna toward the cosmos, we gather hundreds of different signals. Even some of the natural signals are quite suggestive, and one can be tempted to consider them emissions from other civilizations.