Free Astronomy Magazine November-December 2020

45 NOVEMBER-DECEMBER 2020 ASTROBIOLOGY about nine million other living species (of which only 14% are identified), we feel alone as if we were a single organism de- tached from all others. Discovering around another star someone more similar to us than other terrestrial animals and plants whould mitigate our sense of solitude, as well as have heavy implications of a scien- tific, philosophical and religious nature. Based on the principle of mediocrity (dis- cussed in the July-August issue), this senti- ment should be typical of all technological civilizations, or at least those that attempt contact. Therefore, given the insuperable difficulties of an interstellar conversation and considering that the primary purpose should be to simply be sure of the existence of the other, the content of the message sent or expected could be the equivalent of a simple “you are not alone” or “we are here too.” More than anything else, it should be an altruistic act of one civilization towards another civilization, of which the sender of the message sensed the existence by analyzing a planetary atmosphere. Since we are not yet able to let others know that they are not alone, we just have to look for messages of that type arriving at Earth, hop- ing they will be receivable with our instru- ments. If they were sent with more advanced technologies than ours, they could go unnoticed or unheard. Our own technological development does not trend towards the kind of simplified messaging that would be most desirable for a success- ful contact attempt. Therefore, is it not per- haps more reasonable to assume that those who decide to send a message into space would want to do so in a part of the elec- tromagnetic spectrum that is essential to in- telligent life – so essential as to be the reason for a species’ basic awareness of the universe itself? We obviously refer to the light visible to the eyes of ourselves and other evolved animals, light that generally occupies the 400-700 nanometer range of the electromagnetic spectrum. It is difficult to imagine life forms that look at the stars, and therefore the universe, in a totally dif- ferent light than our own. For example, can intelligent life develop on a planet by see- ing the environment in which it evolves in gamma, X or UV rays? A simple “no” may be enough. Similarly, it could not do so by I n the previous page, the fa- mous message from Arecibo sent to unknown be- ings on Novem- ber 16, 1974. Its content is exces- sively anthro- pocentric and childish. After that naive under- taking, another thirty messages were sent with other antennas to individual stars. One of them, the Altair (Morimoto − Hirabayashi) Message, has al- ready reached its destination. The rest will reach different stars be- tween 2022 and 2450. A hypothetical light curve of a star in which an artificial signal has been added, here represented by short peaks emerging from the scatter of the measurements. In a real scenario, the intensity and duration of the peaks, as well as the intervals that separate them, could hide an alien message.