Century-old radio link raises specter for future
By Amanda Jermyn



Reach for the Stars… Amanda Jermyn
December, 2010
Almost exactly 104 years ago, on December 24th, 1906, the first radio program was broadcast on the air by Reginald Fessenden, a Canadian engineer who had worked for Thomas Edison in his New Jersey laboratory. Fessenden’s broadcast from Ocean Bluff-Brant Rock, Massachusetts to ships at sea included him reading the Christmas story from the book of Luke and playing Gounod’s “O, Holy Night” on the violin. It’s a strange thought that since radio waves travel at the speed of light, Fessenden’s broadcast has since traveled 104 light years in all directions from Earth. An advanced alien civilization 104 light years from here might just be listening to this first broadcast right now. Aliens about 70 light years from here might be tuning in to Churchill’s speeches or Nazi propaganda from World War II. If they figured out that the signals they’d picked up in the radio spectrum could be converted to sound, they could hear us. Being aliens, of course, they’d be unlikely to understand our words, but if they had a telescope powerful enough, they could see us.
What aliens might be able to discover about our civilization would depend on the sophistication of their technology. If they’re bacteria or virus-like, forget it! What could be detected might also depend on how much radiation we’re sending into space. Our early radio broadcasts were AM, or amplitude modulation, which emitted much stronger radio waves than the later FM, or frequency modulation system. Today we also have satellite radio where the signals are directed towards Earth from satellites, rather than out into space. So we now emit far fewer radio signals into space than we used to, giving any alien civilization out there a narrow window of about 100 years to pick up strong signals, from the time we started broadcasting until today.
Here on Earth, for the past fifty years, we have been on the look-out for alien civilizations through a scientific organization called SETI, the Search for Extra-Terrestrial Intelligence. SETI uses radio telescopes with large radio antennas to sweep the skies for electromagnetic transmissions from civilizations on other planets. To distinguish such transmissions from naturally occurring radiation throughout the universe, SETI looks for radio signals that are repetitive and have narrow bandwidths, the type emitted by TV and radio communications here on Earth. So far, we have detected nothing, and our chances are slim. Given the vastness of the universe and the roughly 500 extra-solar planets discovered so far, it seems likely that some form of life exists out there other than our own. However, it may be too primitive, making it impossible, without direct contact, to detect, or it may be too advanced, broadcasting from satellites towards its planet so that not much broadcast radiation escapes. Even if there are civilizations out there using radio technology, they may be so far away that even radio waves traveling at the speed of light would take billions of years to reach us. For now, the search goes on, holding out the tantalizing possibility of making contact somewhere in the universe. One can only imagine the wonder and delight of those sailors who heard that first Christmas broadcast of the human voice a hundred years ago. What more awaits us?