Seeking Messages from Aliens
We are seeking messages from an ancient and exotic civilisation, hidden from us not only in time but also in space. But if we should receive a radio message from an extraterrestrial civilization, how could it possibly be understood? Extraterrestrial intelligence will be complex, internally consistent and utterly alien. Extraterrestrials would, of course, wish to make a message sent to us as comprehensible as possible. But how could they?
Is there in any sense an interstellar Rosette stone? We believe there is. We believe there is a common language that all technical civilizations, no matter how different, must have. That common language is science and mathematics. The laws of Nature are same everywhere. The patterns in the spectra of distant stars and galaxies are the same as those for the Sun or for appropriate laboratory experiments: not only do the same chemical elements exist everywhere in the universe, but also the same laws of quantum mechanics that govern the absorption and emission of radiation by atoms apply everywhere as well. Distant galaxies revolving about one another follow the same laws of gravitational physics as govern the motion of an apple falling to Earth, or Voyager on its way to the stars. The patters of Nature are everywhere the same. An interstellar message, intended to be understood by an emerging civilizations, should be easy to decide.
There may be effective methods of communication that have substantial merit: interstellar spacecraft; optical or infrared lasers; pulsed neutrinos; modulated gravity waves; or some other kind of transmission that we will not discover for a thousand years. Advanced civilizations may have graduated far beyond radio for their own communications. But radio is powerful, cheap, fast and simple.
They will know that a backward civilization like ours, wishing to receive messages from the skies, is likely to turn first to radio technology. Perhaps they will have to wheel the radio telescopes out of the Museum of Ancient Technology. If we were to receive a radio message we would know that there would be at the very least one thing we could talk about; radio astronomy.
But is there anyone out there to talk to? With a third or half a trillion stars in our Milky Way Galaxy alone, could ours be the only one accompanied by an inhabited planet? How much likely it is that technical civilizations are a cosmic commonplace, that the Galaxy is pulsing and humming with advanced societies, and, therefore, that the nearest such culture is not so very far away - perhaps transmitting from antennas established on a planet of a naked-eye star just next door.
Is there anyone out there to talk to? Image : © Megan Jorgensen