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confessions of an alien hunter

8 january 2010

Seth Shostak is evidently a scientific celebrity, with a web presence and frequent appearances on radio and TV. It's a measure of my 19th-century lifestyle that I never heard of him till I picked up his book Confessions of an Alien Hunter in my public library. I can't claim full Luddite credentials if I'm reviewing books on my own website, but I have distinctly antiquated ways of becoming hip to the passing scene.

At one point in his chronicle of a career spent in SETI (Search for Extra-Terrestrial Intelligence), Shostak muses that aliens might have media predilections not unlike mine. Most SETI efforts focus on picking up broadcasts from space. But it might be far more efficient to blanket the galaxy with interstellar junk mail. Physical messages in astronautical bottles might be the way we finally hear from ET, phones be damned.

It's a relief to hear that beings of superior intelligence might like to read material texts, just like I do. But of course they might prefer radio, TV, microwaves, visible light, gravity waves, or some more outlandish variety of wireless. One of the few things we know about possible extraterrestrial intelligences is that we don't know what we don't know about them. They could have invented media far beyond our powers to decipher.

Or they might not be writing because they don't exist. Enrico Fermi, the brooding genius behind the harnessing of nuclear fission, speculated that humans were probably alone in the Universe. This wasn't just pessimism. Fermi had good logical grounds for believing us to be exceptional. If the cosmos is full of advanced sentients, then we ought to observe their presence all around us, astronomically speaking.

Of course, except for a vocal minority who believe that the truth is out there, we don't observe aliens at all. Shostak, however, is not surprised by this apparent absence. Interstellar distances are relativistically vast. Faster-than-light communication, let alone travel, seems to be flat-out impossible (not to mention the weird time paradoxes involved). So any messages from space are going to arrive, at best, at the speed of light. Unless advanced civilizations are immortal, and saturate every corner of the galaxy, their transmissions are going to be few and far between.

We're in the position of sailors at sea who have just invented the ship-to-shore radio. There may be bunches of stations out there, but we don't know where to tune the dial or how to direct our primitive antennas. We don't know if ET will be broadcasting continuously or just sending the occasional hailing message; we don't know if she's sending the sum of alien knowledge or the equivalent of a test pattern.

One thing likely is that the aliens haven't heard from us. A staple of science fiction shows extraterrestrials becoming familiar with us by watching Milton Berle or Galaxy Quest or Olympic curling or something, which may be to our advantage or not. But our earliest radio broadcasts are only 90 light-years out from Earth. And unless the aliens have somehow invented the most perfectly-tuned radio sets imaginable, our broadcasts are not going to make a hell of a lot of sense to them. For one thing, they're weak. It was difficult enough sometimes to pick up the Mututal Broadcasting System from across town, back in the day; the static involved in listening from Alpha Centauri would be crazy. For another, as Shostak notes, reception of interstellar signals is going to be a matter of merely hearing that a signal exists. The technical requirements of downloading and decoding its message might well be beyond possibility. And for all that, let's say that some alien ham operator 70 light-years away has just picked up Bing Crosby and would like to write in with his opinions on our musical taste. Even if he e-mails us back tomorrow, we aren't going to hear his remarks till the year 2080. Interstellar IM isn't going to be exactly I.

Confessions of an Alien Hunter is a chatty book of the kind I adore, and I basically ate it up. Shostak is well-placed to deliver a state-of-the-art account of SETI in the early 21st century. He writes with self-deprecatory common sense and is well-attuned to pop culture – though the snappy simile is his fatal Cleopatra, and in time his deadpan tropes come to seem as flat as I-20 between Sweetwater and Odessa.

Overall, if Confessions is a little disappointing, it's only because so much of it seems to be addressed to the underinformed crowd that calls in to talk-radio shows. Almost half the book is taken up with basic exposition of the kind familiar to anyone who has ever watched Carl Sagan. Another long chapter follows, debunking UFO believers – necessary, I suppose, but rather like a book on lunar geology that devotes a chapter to exploding the green cheese hypothesis. Finally, in his last three chapters, Shostak explores recent developments and gives a sketch of his own career (the promised "confessions" of the title). This is good stuff, and I shouldn't carp that it could have been better. Three cheers for Seth Shostak, and . . . keep watching the skies.

Shostak, Seth. Confessions of an Alien Hunter: A scientist's search for extraterrestrial intelligence. Washington, DC: National Geographic, 2009.