for National Geographic News
Are we alone in the universe?
In pursuit of an answer to that formidable question, scientists have for decades been searching the skies with radio waves to pick up any signs of alien life.
They may be looking in the wrong place.
A new study suggests it is more energy efficient to communicate across interstellar space by sending physical material—a sort of message in a bottle—than beams of electromagnetic radiation. Solid matter can hold more information and journey farther than radio waves, which disperse as they travel.
Researchers behind the study speculate that other life-forms may have already sent us messages, perhaps even as organic material embedded in asteroids that have struck Earth.
"Any contact that we might establish with extraterrestrial life-forms is more likely to occur from a physical artifact than from electromagnetic communication," said Christopher Rose, a professor of electrical and computer engineering at Rutgers University in New Brunswick, New Jersey. Rose is a co-author of the study.
The theory is not new, but it is the first time it has been quantified. The research is described in this week's issue of the science journal Nature.
Diluted Signals
Humans have already sent inscribed information into outer space in the hope of reaching alien life.
The Voyager 1 spacecraft has traveled more than 13.5 billion kilometers (8.4 billion miles) since its launch in 1977. It is carrying a 12-inch (30-centimeter) disk containing a message from Earth: sounds and images selected by the late astronomer Carl Sagan and spoken greetings in 55 languages.
But the main focus among alien-hunters has been on electromagnetic radiation—radio and optical waves.
The private SETI Institute in Mountain View, California—its name is an acronym for Search for Extraterrestrial Intelligence—is the most prominent organization involved in the search for intelligent life beyond Earth.
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