Optical SETI in OZ

[LongTomH]

A number of SETI (Search for Extra-Terrestrial Intelligence) researchers don't think ET signals will come in the form of radio. They think intelligent species will prefer to use laser beams to signal over interstellar distances. This approach: Optical SETI is gaining adherents.

One of those is Dr.Ragbir Bhathal:

AFTER you've spent more than 20 years hunting for an alien signal, you think you'd be celebrating if you noticed a mysterious pulse suddenly rising up on your computer readouts. A regular pulse, amid the random clatter of the cosmos, suggests that someone very smart at the other end is sending a message.

But when Ragbir Bhathal, an astrophysicist at the University of Western Sydney, who teaches the only university-based course on SETI (search for extraterrestrial intelligence) in Australia, detected the suspicious signal on a clear night last December, he knew better than to crack open the special bottle of champagne he has tucked away for the history-making occasion.

Instead, he's spent the past few months meticulously investigating whether the unrecognised signature was caused by a glitch in his instrumentation, a rogue astrophysical phenomenon, or some unknown random noise.

Even if he picks up the signal again - he's been scouring the same co-ordinates of the night sky on an almost daily basis since - the scientific rule book dictates he'll need to get it peer-reviewed before he can take his announcement to the world. "And that is a lot of ifs," he concedes.

Dr.Raghal's caution is certainly justified; after all there have been other false alarms. The most famous of those was the "Wow! signal" received by the Big Ear radio telescope at Ohio State University in 1977. It had all the earmarks of a signal from intelligent life: narrow bandwith, and it was within 50 kHz of the hydrogen line (1420.406 mHz). Also, it lasted for 72 seconds, the 'window' expected for the Big Ear as it scanned across the heavens. It was also right off the scale on intensity!

However, it has never been repeated; even after 50 searches of the same area. Still, some SETI researchers can't help still wondering if this might have been a genuine signal from other intelligence.

There's a good chance that this latest 'event' will turn out to be similar to the Wow! event: an intriguing, but unprovable and unrepeatable will-o-the-wisp.

[Duer 157099]

1. Seriously. I mean, look how quickly we moved from radio to internet

like the blink of an eye.

[Phoonzang]

2. I don't know why they assume a signal would be repeated.

Unless they're intentionally blasting a signal at us to get our attention (which means they'd know we're here, which is unlikely), any stray signals we received would probably be short lived.

[joshcryer]

3. There are two important papers about this, METI and SETI beacons:

http://arxiv.org/abs/0810.3966

http://arxiv.org/abs/0810.3964

Basically, "accidents" are unlikely to be discovered, you *need* to send a signal, and then, it has to be periodic over a span of a little while, across the galatic arms. So this is the right way to go about searching for beacons.

[Phoonzang]

5. Thanks for the links.

So far I've only had time to skim those papers, but they're pretty interesting. I especially found the part where they said that we might be in the "backwater" of the galactic habitable zone interesting. Anyway, I assume these beacons won't be omnidiretion but instead will be narrow focused? So from what I gathered, if the aliens creating these very expensive beacons wanted someone to hear the signal, they'd be using educated guesses. Focus on one area, move to another, then eventually cycle back to the original area?

Edit: Ok...like you said...a lighthouse.

[joshcryer]

4. Note that the idea of sending beacons isn't predicated on "knowing" of others being out there.

Think of it more like a lighthouse rather than a concerted effort to contact a single civilization. Basically saying "we are here."

[Orsino]

7. I don't think that's their assumption.

They do realize, however, that unless it repeats, there's no chance of confirmation.

[Ganja Ninja]

6. I think what we really should be doing is asking what signals we produce

would be most detectable from another planet. If intelligent life is out there it's probably going to be living under similar conditions as us. So we need to decide what signals carry the farthest and concentrate on them.