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Weird Ways to Search for ET

A look at the SETI Institute's Allen Telescope Array at Hat Creek Observatory about 290 miles northeast of San Francisco, Calif.
A look at the SETI Institute's Allen Telescope Array at Hat Creek Observatory about 290 miles northeast of San Francisco, Calif. (Image credit: SETI Institute)

Despite theaccusations of my correspondents, I try to keep an open mind about our searchfor ET.?

That?s notentirely trivial. Scientists, whose job description is to learn somethingwonderfully new, are just as human as the next haberdashed hominid. Afterpursuing an exploratory experiment for years or decades, they inevitably buildup both a psychological and monetary investment in their strategy. They caneasily become thoroughly marinated in their current approach, and dismiss otherideas with a sneer and a wave.

I try notto do that, and I credit my colleagues with the same.

It?s aconstant battle, as SETIscientists (and string theorists, for that matter) are often accused of fallingdown the wrong rabbit hole. If only they?d adopt a completely different researchtack, it?s said, they could look forward to stashing a Nobel medal in theirdesk drawer.

?Why wastetime looking for old-style radio signals,? many people have written me,?when the aliens will be shooting neutrinos our way?? Neutrinos are one of manytypes of suggestions for ?weird SETI? that make sense, but perhaps notoverwhelming sense. These ghostly particles have the advantage of barrelingright through such petty obstacles as planets, which means you don?t have toworry much about where to aim your ?telescope? ? the signal could even comefrom behind you. The problem with these particles is that they cost atremendous amount of energy to produce, and our neutrino detection efficiencyis really low.?

Quantumentanglement has become an oft-heard phrase at the low-grade parties I frequent.?The aliens will use entangled particles to signal us,? many tell me.?

At firstblush, this sounds like a nifty idea. QE could offer the gold standard forinterstellar chit-chat: inexpensive and instantaneous ? a kind of subspacecommunication channel a la ?Star Trek.??

Well, youcan put that thought away for now. A subtle piece of logic known as Bell?s theorem shows that, despite the spooky action at a distance of entangled particles,they?re not instruments for faster-than-lightshout-outs.

Anotherperennially popular refrain with correspondents is to suggest looking forgravity waves, probably because a lot of people make the unwarranted assumptionthat gravity propagates faster than light. As far as we know, it doesn?t, and (likeneutrinos) gravity waves are difficult to generate and painfully hard todetect.

There?s a raftof clever schemes for sending information from one place to the next if youdon?t demand a lot of bandwidth (which translates into the speed of information?conveyed). I?ve written before about how garrulous aliens might grab ourattention with a flash of laser light beamed our way. This might be aonce-a-month or even once-a-century signal, but that would be good enough. Afterall, if a periodic, bright flash were to be seen on some random patch of sky, legionsof astronomers would relentlessly study that position ? and perhaps turn up alow-power broadcast with gobs of useful information (such as the meaning oflife, or how to make a perfect souffl?).

Luc Arnold,a French astronomer, has suggested that aliens mightsignal us with giant shadow puppets. Possibly inspired by NASA?s Keplermission, which uses a space-based telescope to find small planets by the slightdimming they induce when passing in front of their home stars, Arnold opined thatthe aliens might produce a simple signal that Kepler ? or something like it ? couldeasily find. A signal that?s always ?on the air.?

The idea isthat the extraterrestrials would construct big, opaque polygonal structures,and sling them into orbit around their sun. Anyone observing stars using atechnique similar to the Kepler telescope could notice one of these lightblockers.? If the screens were some shape other than round, the time pattern ofthe observed dimming would tip off distant astronomers that they hadn?t found aplanet ? rather, they?d discovered a manufactured object.

None ofthese types of ?transmissions? is currently the subject of SETI scrutiny, and thatmight sound as if we?ve got deaf ears to new ideas. Well, not to worry. Theseschemes may be pursued by others.? Neutrino and gravity wave detectors arebeing deployed by physicists, and Kepler is collecting data as we speak. Andfrankly, there?s ample precedent for serendipity in exploration.? Think of the1967 discovery of pulsars.? They were found by a radio astronomer who wasn?tlooking for anything of the kind.? Quasars were also found by accident (as wasViagra).

So in somesense, traditional SETI ? which after all, involves only a few dozenprofessional researchers world-wide ? has backup; namely physicists, and justabout the entire field of astronomy. That?s a good thing, because SETI fundingis still too cramped to permit its practitioners to test a whole lot of differentstrategies.

As for me,I try to constantly reassess our work by keeping an open mind about new approaches.?So far, none has swayed me from our schemes to hunt for light or radio signals.But if a slicker idea comes along ? even if it?s weird ? well, I?m willing togive it an audition.

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Seth Shostak is the author of Confessions of an Alien Hunter.

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Seth Shostak is an astronomer at the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California, who places a high priority on communicating science to the public. In addition to his many academic papers, Seth has published hundreds of popular science articles, and not just for; he makes regular contributions to NBC News MACH, for example. Seth has also co-authored a college textbook on astrobiology and written three popular science books on SETI, including "Confessions of an Alien Hunter" (National Geographic, 2009). In addition, Seth ahosts the SETI Institute's weekly radio show, "Big Picture Science."