Should we be phoning ET ?

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: Signals ranging from whale songs to Craigslist classifieds have been sent upward via TV transmission dishes. In February, NASA used its Deep Space Network to send a Beatles tune toward Polaris. Just last month, a Doritos commercial was beamed to Ursa Major.