A little over half a century ago, saw the beginning of project Ozma (named for the princess ruling the fictional country of Oz), which continued with the SETI program (Search for ExtraTerrestrial Intelligence). Assuming that there must be many cases of extraterrestrial intelligence, most of which will undoubtedly have reached a technology capable of communicating by means of electromagnetic waves, surely some of them are sending messages that perhaps we can detect and answer. Initially it was thought that we could take the initiative, sending messages to stars that might harbor planets with life similar to ours, but this was soon considered too expensive, so all efforts were allotted to intercept messages, not necessarily addressed to us. After half a century of efforts, nothing has been achieved. There have been a few false alarms, but none that has been confirmed.
In a previous article I mentioned the Fermi paradox, which holds that we must be alone in the galaxy, because otherwise any extraterrestrial intelligence with several million years advantage would by now be here, because it would not take long to colonize the whole galaxy, even at the interstellar speeds we will reach in the next few centuries.