Looking for alien life

Artist's impression of a planet orbiting a star

Scientists have been listening for possible signals from alien civilisations for 50 years, but so far nothing has been detected. Some think it is time to reconsider the approach currently being taken.

  • Listening for radio signals from aliens
  • Nothing found in the past 50 years
  • New approach has been suggested

For 50 years, humans have scanned the skies with radio telescopes for distant electronic signals indicating the existence of intelligent alien life. The search—centred at the SETI Institute in Mountain View, California—has tapped into our collective fascination with the concept that we may not be alone in the universe.

But the effort has so far proved fruitless, and the scientific community driving the SETI project has begun questioning its methodology, which entails listening to specific nearby stars for unusual blips or bleeps. Is there a better approach?

UC Irvine astrophysicist Gregory Benford and his twin, James—a fellow physicist specialising in high-powered microwave technology—believe there is, and their ideas are garnering attention.

In two studies published in the June issue of the journal Astrobiology, the Benford brothers, along with James’s son Dominic, a NASA scientist, examine the perspective of a civilisation sending signals into space—or, as Gregory Benford puts it, “the point of view of the guys paying the bill.”

“Our grandfather used to say, ‘Talk is cheap, but whiskey costs money,’” the physics professor says. “Whatever the life form, evolution selects for economy of resources. Broadcasting is expensive, and transmitting signals across light-years would require considerable resources.”

Assuming that an alien civilisation would strive to optimise costs, limit waste and make its signalling technology more efficient, the Benfords propose that these signals would not be continuously blasted out in all directions but rather would be pulsed, narrowly directed and broadband in the 1-to-10-gigahertz range.

Astrophysicist Gregory Benford

Astrophysicist Gregory Benford believes an alien civilization would transmit “cost-optimized” signals rather than the kind sought for decades by the SETI Institute.

“This approach is more like Twitter and less like War and Peace,” says James Benford, founder and president of Microwave Sciences Inc. in Lafayette, California.

A new approach suggested

Their concept of short, targeted blips has been dubbed “Benford beacons”. Well-known cosmologist Paul Davies, in his 2010 book The Eerie Silence: Renewing Our Search for Alien Intelligence, supports the concept.

This means that SETI—which focuses its receivers on narrow-band input—may be looking for the wrong kind of signals. The Benfords and a growing number of scientists involved in the hunt for extraterrestrial life advocate adjusting SETI receivers to maximise their ability to detect direct, broadband beacon blasts.

But where to look? The Benfords’ frugal-alien model points to our own Milky Way galaxy, especially the centre, where 90 percent of its stars are clustered.

“The stars there are a billion years older than our Sun, which suggests a greater possibility of contact with an advanced civilisation than does pointing SETI receivers outward to the newer and less crowded edge of our galaxy,” Gregory Benford says.

“Will searching for distant messages work? Is there intelligent life out there? The SETI effort is worth continuing, but our common-sense beacons approach seems more likely to answer those questions.”

The following is a lecture given by James Benford on the Benford beacon concept:

Adapted from information issued by the University of California, Irvine / Steve Zylius / University Communications / SETI Institute.

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