Dec. 9, 2004 — -- 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."