Searches for extraterrestrial intelligence are about
to expand into new realms, thanks to new advances
in technology — and new thinking.

Adapted from Sky & Telescope, April 2001

As far as we know, we're alone in the universe. Sure, it's conceivable that bacteria-like organisms live in wet, underground soils on Mars. Maybe alien sea creatures even swim the dark waters beneath Europa's icy crust. But nearby life, if it exists at all, is undoubtedly dumb. If we want to look for smarter extraterrestrial biology — the kind that could rival or perhaps far surpass us humans for reasoning, inventing, and building — we have to look much farther afield, among the stars. And we don't know where.

Planets inhabited by high technologies (if they exist at all) are surely much rarer than planets inhabited by bacteria. After all, microbes were Earth's most advanced life forms for nearly a million times longer than the span of written human history. But a tantalizing prospect fires the imagination: the rare technological worlds may actually be the easiest to find. Unlike bacteria, intelligent creatures could choose to make themselves known across vast interstellar distances. They could do it with radio transmitters or lasers not much bigger than our own. Maybe they are doing it right now.

Searches for extraterrestrial intelligence (abbreviated SETI) have no obvious hunting ground and no clear route to discovery. Instead, after more than 40 years researchers have amassed a mountain of speculation and only a small hill of experiment. If sentient beings exist among the stars, they have remained beyond the grasp of our instruments.

But perhaps not for long.

New ideas are stirring in the world of SETI. A small group of scientists and engineers have been busy for several years discussing how to expand our ability to detect artificial transmissions from deep space. Their task was to reason out what new instruments should be used and how best we might rake the skies for plausible alien signals.

The task is daunting. To begin with, the sky is huge — with 400 billion stars (and possibly as many planets) in our galaxy alone. The radio spectrum is also huge — with roughly 10 billion channels to scan per star, and that's just in the "microwave window" of frequencies that come in best through Earth's atmosphere. The distance any signal has to travel is astronomical — so it will be weakened by an astronomical amount squared. It has been said that SETI is like looking for a needle in a haystack. But if the instruments proposed by this group are built, SETI scientists will stop sifting the hay with spoons; they'll have a pitchfork.

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