For all those folks out there who are counting the days until we hear from some intelligent creature on another planet, researchers now say we're not going to be able to eavesdrop on the space alien equivalent of "I Love Lucy."
During the few decades that scientists have searched systematically for life elsewhere in the universe there has been some hope that electromagnetic "leakage" from communications systems on other planets -- such as television broadcasts -- might be detectable from Earth. If that's the case, then radio telescopes sweeping the sky might pick up those signals, giving us a window onto other worlds, and finally answering that increasingly overworked question, "Are we alone?"
Don't count on it, say researchers from three institutions. Any advanced civilization would likely encode and compress its communications to make its systems more efficient, just as your computer compresses files that you send over the Internet, the researchers argue in a report in the American Journal of Physics.
And that, they say, would make those signals indistinguishable from the thermal radiation of stars, and thus impossible to detect because it would seem like part of the universe's background noise.
Even if we did somehow capture such a signal, we wouldn't know it, says physicist Mark Newman of the University of Michigan in Ann Arbor.
"If you don't know how to decode it, then you can't make out what's going on," Newman says.
A computer can't show a picture that has been compressed by another computer unless it knows how to decompress it, and likewise we couldn't decode a television signal that had been compressed unless we already knew the code. And, Newman and his colleagues argue, any advanced civilization that has used wireless communications for even a few decades would surely have figured out that it makes sense to encode.
We're already doing it, and we're just barely in the communications age.
"This is something we already do in many of our transmissions," Newman says. "We encode (compress) them so they take up less space and we can send them faster and send more messages."
To be fair, the Search for Extraterrestrial Intelligence has never been wedded to the idea that we could somehow tune in to alien television broadcasts. Astronomer Frank Drake, who many consider the father of the current effort, told me years ago that any such signal would probably be far too weak to detect on Earth.
Thus the primary aim is to find signals that are intentionally sent in our direction by another life form, and thus designed to be easily detected by us. Newman has been informed of that by many irate readers of his report who maintain that the search is viable because no one is really listening for Lucy.
Yet much of the SETI literature does suggest that ordinary communications signals might be detectable.
And that's what compelled Newman and biologist Michael Lachmann of the Max Planck Institute in Leipzig, Germany, and computer scientist Christopher Moore of the University of New Mexico in Albuquerque to take a closer look.
The three built on the pioneering research of Claude Shannon, an electrical engineer with Bell Labs who published two seminal papers in the 1940s on information theory. Shannon demonstrated that it is possible to compress data and thus distribute far more information than would otherwise be possible. That work is the foundation for much of today's communication technology.