The Search for Extraterrestrial Intelligence (SETI) has been dominated for its first half century by a hunt for unusual radio signals transmitted by an advanced civilization. Writing exclusively in March’s Physics World, Davies, director of BEYOND: Center for Fundamental Concepts in Science at Arizona State University in the US, explains why the search for radio signals is limited and how we might progress.
Questioning the idea of an alien civilization beaming radio signals towards Earth, Davies explains that even if the aliens were, say, 500 light years away (close by SETI standards), the aliens would be communicating with Earth in 1510 – long before we were equipped to pick up radio signals.
While SETI activity has been concentrated in radio astronomy, from Frank Drake’s early telescope to the more recent Allen Telescope Array, astronomers have only ever been met with an (almost) eerie silence. Within the next decade, Frank Drake says that the Earth will go "radio silent" due to the advent of underground fiber optic delivery of Internet and wireless traffic and sateliite transmission that beams its signals back to Earth, rather that out to the Milky Way at large.
Davies suggests that there may be more convincing signs of intelligent alien life, either here on Earth in the form of bizarre microorganisms that somehow found their way to Earth, or in space, through spotting the anomalous absence of, for example, energy-generating particles that an alien life form might have harvested.
“Using the full array of scientific methods from genomics to neutrino astrophysics,” Davies writes, “we should begin to scrutinise the solar system and our region of the galaxy for any hint of past or present cosmic company.”
The Daily Galaxy via the Institute of Physics