Optical SETI

R3 writes "BBC News is running this story, about SETI's renewed efforts to find ETs who might be flashing us with light, instead of radio-waves:"

Comments

Re:optical detection sounds hard

[Mark Hood]

> wouldn't we have to depend on the fact that
> the other civilization know that we are right
> here, and that we are able to pick up their
> signals?

Yes, that's true if we assume they're trying to contact US specifically. If they've just got a huge laser on the top of their local Everest-sized mountain & are relying on their planet's rotation to turn it into a beacon we have a better chance of spotting it.

If we try to pick up radio we can (in theory) spot their TV signals, satellite communications & Star Wars ABM radars :)

> No matter what kind of transmission ET is using
> he will have to hope that we are able to pick
> up the signals

Of course - and that's why the Seti League (http://www.setileague.org/) advocate lots of smaller dishes. Their argument is that while an Arecibo size dish can look further, this comes at the cost of seeing a smaller area of the sky. Their favourite statistic is 'even if we're looking on the right frequency at the right time, there's a 99.999% chance that when the call comes in, we'll be looking the wrong way'.

Of course, they're talking about radio waves, but the same argument holds for optical SETI.

Mark
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