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Should we be phoning E.T.?

This plaque, placed on
NASA probes in 1972 and 1973, depicts humans
and Earth's location.

We've been listening for the signs of extraterrestrial civilizations for nearly 50 years - and if E.T.s are out there, they just might have picked up on the radio signals that we've been transmitting for even longer. More recently, some broadcasters have been sending intentional shout-outs to the aliens.

Is that so wrong?

Yes, in the opinion of physicist-novelist David Brin and other scientists who say such transmissions could bring unwelcome consequences.

For years, Brin has been concerned about the idea of phoning E.T. - a practice he calls METI. That stands for "messages to extraterrestrial intelligence," as opposed to SETI, or the search for extraterrestrial intelligence. In an essay titled "Shouting at the Cosmos," written for the Lifeboat Foundation, Brin said the idea of sending high-powered messages to E.T. represented a worrisome turn in the SETI search:

"If aliens are so advanced and altruistic ... and yet are choosing to remain silent ... should we not consider following their example and doing likewise? At least for a little while? Is it possible that they are silent because they know something we don't know?"

One worry might be that the aliens who respond to the phone call won't look like the cute little fellow in the movie "E.T.," but more like the villains of "Independence Day" or "War of the Worlds." (Or, for that matter, "The X-Files," which returns to the big screen next week.) Brin doesn't explicitly mention an alien invasion, but he does voice deep concern about "shouting into an unknown jungle that we do not understand."

Over the past couple of years, there's been a good deal of cosmic shouting - or, more accurately, singing and shilling:

TV broadcasts probably don't make that much of a dent in the cosmos, as the SETI Institute's Seth Shostak reported in a 2004 research paper. But Brin is worried that the high-powered signals just might get the wrong kind of attention, and for the past couple of years he's been trying to get something done about it.

This schematic shows the
coded message sent out
from the Arecibo Observatory
in 1974. Click here for
the graphic's meaning.

One opportunity came and went in 2006, when a study group for the International Academy of Astronautics discussed SETI issues at a meeting in Spain. Brin and other participants hoped that the group would come up with a procedure for considering and clearing messages meant for E.T., but the issue wasn't addressed to his satisfaction.

Since then, retired U.S. diplomat Michael Michaud and John Billingham, former chief of NASA's SETI office, reportedly resigned from the study group in protest - and Brin is gearing up for another opportunity to get some exposure for the issue. The IAA is due to discuss active SETI and other topics during a September symposium in Paris.

"It looks likely to be yet another staged, Potemkin exercise," Brin told me in an e-mail exchange. "Those who are not present will be ridiculed as 'panicking over Cardassian war fleets' and seeking 'censorship' (neither of which have even remotely been mentioned)."

The possibilities could include setting up a procedure for transmitting messages to target star systems, just as there is an IAA-approved procedure for spreading the word about a confirmed message from E.T. The process might bring in the United Nations or the International Astronomical Union, but the important thing for Brin is that the issue gets a serious airing.

He's already gotten some support from some corners of the blogosphere as well as from space exploration advocates such as Space Policy Consulting's Charles Miller. In an e-mail, Miller said transmissions to E.T. risked exposing Earth to catastrophic consequences, and thus could constitute "crimes against humanity."

Most experts on SETI would reject that indictment. They argue that Earth is already signaling its presence through high-powered military radars, that the vast distances between star systems would insulate civilizations from each other, and that any civilization capable of communicating with others would likely have already gone through its awkward phase.

I realize this is starting to sound like a "Star Trek" episode. It might seem crazy to be concerned about the coming alien invasion when there are more immediate problems to worry about, such as the price of gasoline and the housing crisis.

Even when you consider cosmic threats from space, there's a big distinction between the threats that are already known to occur - such as huge asteroid impacts or supernova blasts - and the threats that depend on what appears to be a string of unlikely propositions. How do you weigh the chances that inimical intelligent life exists on other planets that are close enough to possibly pose a threat?

Brin himself has written about some way-out doomsdays, such as the possibility that a microscopic black hole could destroy the earth. He used that plot device in his 1990 science-fiction novel "Earth." Since then, scientists have gone through a lot of effort to argue that such a scenario couldn't happen in reality.

In one of his e-mails, Brin drew a parallel between the black-hole controversy and the discussion over sending messages to extraterrestrial intelligence:

"The mini-black hole threat is similar to the METI threat in that both are examples of 21st-century quandaries concerning low-probability, high-consequence potential failure modes.

"There is an active discussion site concerning 'existential threats' on the Lifeboat site.  And Nick Bostrum and others have been cataloguing such threats in a way that might lead to improved risk analysis. But we are still in early days and it seems a devilishly vexing problem.

"At one end, you have Bill Joy, Michael Crichton and Ted Kaczynski, variously proposing 'renunciation' as our only way to avoid a 'bad singularity.'  The far right turns anti-science while the far left despises Big Engineering.

"At the other extreme are those who blithely assume that troglodyte-luddites will be proved wrong by accelerating intelligence.

"For more, see: http://lifeboat.com/ex/singularities.and.nightmares

"It puts pragmatic-enlightenment civilization in a bind.  One that I am portraying in my new novel.

"It really ought to be the topic of a major, major conference. Ah, well. Let me know if possibilities occur."

What do you think? Should there be a First Amendment right to phone E.T.? Should broadcasts to the aliens be regulated? Or is this an issue not worth caring about? Feel free to weigh in with your comments below.

Update for 3:30 p.m. ET July 15: Seth Shostak, senior astronomer at the SETI Institute, got back to me and pointed out that the issue of detecting our signals is really a question of how big a detector the aliens might have. If the antenna is sensitive enough, even early TV signals could be picked up tens of light-years away from Earth.

There's also the question of Earth's unconcealable atmospheric signature: Click through the comments below for insights from Brian McConnell, author of "Beyond Contact: A Guide to SETI and Communicating With Alien Civilizations."

Right now, the controversy is playing out over theoretical what-ifs, and it's hard to tell whether any intentional signals would have an effect. The discussion would have a sharper focus if a signal from an alien civilization were ever detected.

"If you find a signal, then you know where you would want to send a response," said Shostak, who chairs the IAA's SETI Permanent Study Group. The proposed reply would become the subject of intense scientific - and political - discussion.

The procedures for handling any messages to and from E.T. would likely be discussed at the September symposium in Paris, as well as a meeting that will follow in Glasgow, Scotland.

"The current protocols are in fact a gentleman's agreement among some of the SETI folk, and they really don't have the force of international law," Shostak pointed out. "In fact, not all practitioners of SETI have signed onto the current protocols. The fundamental purpose of the protocols is merely to reassure the public that there will be no secrecy, and they will know what's going on."