“If we are not alone in the Universe, why have we never picked up signals from an extraterrestrial civilisation? This long-standing puzzle, known as the Fermi paradox after physicist Enrico Fermi, who first posed the question, is still one of the strongest arguments against the existence of intelligent aliens.
But two physicists have come up with an intriguing solution. They suggest a way in which aliens could send messages to each other across space that not only disguises their locations but also makes it impossible for a casual observer to even distinguish the messages from background noise. Messages sent by this method could be criss-crossing our Galaxy without us ever knowing.
At first glance, sending a message without giving away your location appears impossible. If a signal – a stream of photons – comes from a single source, its origin can always be determined by measuring the direction of recoil of a detector struck by the photons. But Walter Simmons and his colleague Sandip Pakvasa from the University of Hawaii at Manoa have come up with a cunning way around this.” New Scientist [via EurekAlert!]
[It doesn’t seem very plausible to me; read the article. “I want to believe…”]