E.T., don't phone home, a letter may work better

A Rutgers University expert in wireless communications says he knows the best way to contact aliens in deep space.

Send a message in a bottle.

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He isn't kidding.

Lobbing inscribed objects across the universe is more energy efficient than broadcasting into the void, computer science professor Christopher Rose contends in today's cover story for the journal Nature.

"If you're going to think about transmitting large messages over long distances, you really want to look at inscribed matter as a possibility," the scientist says in an interview.

That would seem to border on heresy for Rose, a 47-year-old associate director of the Wireless Networks Laboratory at Rutgers in Piscataway. He has worked at Bell Labs, which pioneered satellite communications for AT&T. He even shared an award last year named for Guglielmo Marconi, dubbed the father of radio.

But Rose and physicist Gregory Wright of Fair Haven, another former Bell Labs employee, say the numbers don't lie. After crunching a galaxy of them, they conclude the odds of a message reaching some far-flung space creature are greater if the missive is catapulted on a sturdy rock than by electromagnetically beaming it.

That is because radio waves disperse and weaken as they travel. Think of a flashlight beam or laser pointer.

And if E.T. happens to be listening to a ballgame instead of scanning for our radio messages, it means we must keep retransmitting.

A physical message, on the other hand, is permanent -- assuming it can be shielded from cosmic radiation and aimed where someone or something might find it. Say, onto a planet or into an asteroid belt.

It's still a needle-in-a-haystack proposition, of course.

"Space is really big," says Rose, whose findings emerged from his studies of ways to pack more bits of information into wireless signals.

Physical messages already are wending their way through the cosmos. Twin Pioneer spacecraft each bear metal plaques with their return address. Voyagers 1 and 2 carry time capsules compiled by the late scientist Carl Sagan and others. Gold-plated copper phonograph disks on each Voyager contain more than 100 earthly images, along with sounds ranging from wind and whales to Bach and Chuck Berry. There is even a written greeting from Jimmy Carter.

Astronomers say the only broadcasts aliens are likely to receive these days are TV re-runs and other stray signals leaking into space.

In 1974, the Arecibo radio telescope in Puerto Rico beamed a three-minute message toward star cluster M13 at the edge of the Milky Way. The message consisted of binary code -- ones and zeros, indicated by shifting frequencies -- that if properly decoded would yield a simple picture depicting our solar system, DNA and a stick figure of a human. For three days in 1999, a Houston company used a radio telescope in Ukraine to pulse a similar pictorial at four stars roughly 60 light-years away.

Nobody has answered so far.

"Those were mostly in the nature of demos, to show how you could do it," said astronomer Seth Shostak of the SETI Institute, a California nonprofit group that has pursued the search for extraterrestrial intelligence for two decades. "We think the odds they're out there are 100 percent."

Radio signals from Earth peter out quickly and might reach a few stars at best, said David Anderson of SETI@home, a research project based at the University of California, Berkeley, that uses the power of millions of home PCs to search for radio signals from space.

Still, hope dies hard. A focused radio beam possibly could reach the far side of the galaxy. "And advanced aliens might have the ability to send much more powerful signals than we do" in response, says Anderson in an e-mail.

But physical messages start making practical sense for distances beyond Saturn, says Rose, a graduate of the Massachusetts Institute of Technology. He suggests alien calling cards may be encoded and embedded all around us.

"Impact craters might be advertisements," he jokes.

Despite the lofty title of his Nature article -- "Inscribed matter as an energy-efficient means of communication with an extra-terrestrial civilization" -- Rose's manner is down-to-earth. A fan of "2001: A Space Odyssey" and "The Matrix," his Rutgers Web site features student cartoons of aliens and humans shooting books and paper airplanes at each other. One entry from a colleague depicts a man flattened by a rock.

"A simple hello would have sufficed," the victim mutters.

Actually, simple hellos probably would serve no useful purpose, according to Rose. Stars are so distant that human senders would be long dead before any reply arrived.

So he and Wright favor lengthier statements, for celestial posterity. Short-lived civilizations could help others avoid the same fate, by describing natural or self-inflicted calamities. Humans even might attempt to seed the heavens with their DNA. The theory of panspermia -- germs or spores spreading life through the universe--was touted by the late Nobel laureate Francis Crick.

Kevin Coughlin covers technology. He can be reached at kcough lin@starledger.com or (973) 392-1763.