QS2
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Detecting Civilization in our Universe
So I was thinking until recently that there was no way you could detect an Earth like civilization within our Galaxy without a ridiculously large array of Radio Telescopes, when I saw this
, which as it says in the Wikipedia article is the planned Square Kilometer Array.
What really caught my attention though and I found some other references to is, is that this array will have the sensitivity to detect a current Earth for up to a few hundred to thousands of light years range. As usual I suppose this is an example of reality surpassing your imagination. However this also probably means that any advanced alien species could easily make an array that could I suppose detect Earth from anywhere in this Galaxy, well once our radio signals get there of course... 
So what do you think, will the aliens from SF learn about humans via radio waves long before say a human spacecraft could arrive, or is this just something that has little importance within SF?
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1/9/2008, 8:14 pm
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QS2
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Re: Detecting Civilization in our Universe
There is a standard answer to that opinion Corvus, very simple when you think about it. You do what you can, not necessarily what you should. Mainly because you really can only do what you can, as such we will for now try with Radio and optical and hope we get lucky.
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1/9/2008, 9:06 pm
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Reythia
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Re: Detecting Civilization in our Universe
Interesting. I hadn't heard about that before.
Okay, so before I say any more, let me note that I'm interested in the topic and think the array is a good idea. I just want to point that out here and now because I suspect that otherwise I'll come out sounding like a cynic!
See, the reasons I think it's a good idea is mostly astronomical, and have very little to do with finding alien signals. It's not that it's impossible to concieve of hearing an alien broadcast, but I see a few flaws in using it as a SETI tactic:
1.) Unless an alien culture is consciously transmitting a continuous and probably repeated signal, could we determine that the signal was non-natural in origin? At best, we could become curious, which could lead to further investigation. But if it was a "local" alien signal, like a TV signal, it wouldn't repeat (much), and it might not be comprehensible to us. We could probably CLAIM it was an alien signal, but it'd be hard to prove. Also, given the amount of radio noise in the area, it might be difficult to make out the full message. Could you determine that Morse Code was a language if you only heard intermittant dots and dashes, and if noise had erased half of them and added false blips in incorrect places? Maybe, if you know Morse Code, you could make a decent stab at it. But what if you'd never heard of even the idea of Morse Code? Would you listen to it for a while, then finally decide, "Well, maybe that's someone, or maybe it's just the interference of pulsars farther away"? Either way, it would likely be hard to prove (though, either way, it would be worth further study!)
2.) If the aliens were intentionally broadcasting a signal to us (rather than a locally-used signal), there's hopefully a better chance of us understanding that it is a signal. So in this scenario, let's pretend that we've recieved a reasonably-long radio series and have determined that it is most likely alien (and non-natural) in nature. Sweet! Talk about a huge boost to moral on Earth: we are not alone! ...And yet, from a practical standpoint, what could we do about it? Obviously, we could point a big radio source in their direction and start beaming them our encyclopedias. But unless their star is relatively near ours (or they have FTL travel, I suppose), the short- and mid-term effects of this will likely be nil. If it takes a hundred years for our signal to get to them, and a hundred years for their reply to get back to us (assuming they even caught our signal, that is), well... that's a heck of a way to hold a conversation! What should we do in such a situation? What if we didn't understand their original message, even?
Anyhow, I'm done with my tangent. Like I said before, I agree that this SKA is a good idea. I am just skeptical that it (or any other SETI) will accomplish a great deal at this point in time. Then again, I could be wrong.
---  -- YAR! |
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1/9/2008, 9:16 pm
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QS2
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Re: Detecting Civilization in our Universe
Obviously an array this large isn't going to be built for SETI, however it is known I believe that Jupiters and Super Jupiters can have considerable radio noise, probably not as much as we produce, if I remember correctly, but a lot.
As such the array might be used to try and listen in on gas giants around nearby stars to learn more about planets. But obviously if by some odd lucky chance some idiots like us are nearby irradiating the entire space with their own radio waves, we'd detect that as well I guess. 
I can't say I have my hopes up, but hey, finally we will have something that can actually hear the aliens without them having to send to us on purpose. At the very least it will let us further refine the minimum limits of the Drake Equation as well if we find nothing at all, which I think is what everyone expects these days. 
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1/9/2008, 9:58 pm
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Reythia
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Re: Detecting Civilization in our Universe
Agreed, on all accounts.
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1/9/2008, 10:20 pm
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