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Active SETI?

I think the fear about sending these signals into space is largely unjustified.

For it to be a danger requires:
a) something there to receive it
b) that can interpret it as an intelligent signal,
c) has the ability to get here,
d) cares enough to make the trip,
e) and want to kill us when they do.

If all of that were true, we'd likely have encountered them already.
 
I think most of this discussion is moot:
1--> Even the most powerful radio signals from decades ago have been lost as interstellar background noise by now. I haven't done the comparison, but I have a feeling that if you compared the energy loss of those signals to stellar background radiation, they probably weren't detectable by the edge of the solar system, much less at the nearest star system.
2--> Virtually every realm of the electromagnetic spectrum today is regulated. You can't make loud noise on the radio, or the FCC will shut you down. Ever own a walkie-talkie (or for that matter, anything that's electronic with a chance for transmission)? Remember that label on it? It meets requirement such-and-such from the FCC in that it can cause no harmful interference and it must accept any interference. Given how much companies are bidding for radio frequencies, you aren't going to be able to pull it off.
3--> Other means, such as lasers, aren't coherent enough to work.
4--> If one were so inclined as to go about this, the only realistic method is the detonation of multiple nuclear warheads in orbit in patterned succession. I don't think anybody's going to try that. The other alternative is... putting records and plaques on the side of interstellar satellites (e.g. Voyager). Based on Star Trek, it's pretty clear that one's going to come back to bite us in the @$$.

All kidding aside, I really don't think this is true. Joe-Bob ain't gonna raise ET's friends on his radio fashioned out of 80's electronics.
 
T-Diddy said:
All kidding aside, I really don't think this is true. Joe-Bob ain't gonna raise ET's friends on his radio fashioned out of 80's electronics.
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Well, T, its happening today. Not by joe-bob in his backyard, but by powerful radio antenna telescopes across the globe. We're (they're?) actively trying to contact alien civilizations by broadcasting targeted messages at probably points in the sky. That capability may not ever be entirely available to the average Joe - but maybe.
 
Loss Leader said:
According to the book The World Without Us, some scientists tried beaming a signal in the seventies and public reaction was extremely negative for reasons of people not wanting our location broadcast.
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That's because that Dick Nixon was the President and we were embarrassed to let the aliens see our leadership.

But now that we are under the enlightened leadership of George W. Bush we can...oh, wait. Never mind.

A
 
madurobob said:
Well, T, its happening today. Not by joe-bob in his backyard, but by powerful radio antenna telescopes across the globe. We're (they're?) actively trying to contact alien civilizations by broadcasting targeted messages at probably points in the sky. That capability may not ever be entirely available to the average Joe - but maybe.
Click to expand...



Umm..correct me if I'm wrong, but aren't those powerful radio telescopes (like that at Arecibo) "receivers" that collect information and not "transmitters" that send out information? I've always thought they were use solely as receivers.
 
madurobob said:
Well, T, its happening today. Not by joe-bob in his backyard, but by powerful radio antenna telescopes across the globe. We're (they're?) actively trying to contact alien civilizations by broadcasting targeted messages at probably points in the sky. That capability may not ever be entirely available to the average Joe - but maybe.
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I don't believe you. Prove it by citing at least one scholarly publication regarding actual use of a radio telescope for active SETI. It would certainly appear, since demand for time with radio telescopes is incredible, and only goes to real, publishing scientists. I couldn't find a single relevant hit on several pages of search engine results.

I also don't believe it because where the heck are you going to send it that has any elevated chance of a terrestrial planet? We're only starting to be able to detect gas giants, let alone smaller planets. (thus, it would probably be a waste of time for a radio telescope, thus they probably wouldn't do it since other scientists have better uses)

I also don't think radio 'telescopes' work as radio 'transmitters.' I may be wrong about that one, as I'm not an expert on them, but it would scramble most of the radio reception around it, and as I said before, it's big bucks. Note that Arecibo is an 'observatory,' not a 'transmitter.'

I'm actively calling out the folks who think this is a real phenomenon. Prove it or quite pretending to know what you're talking about. The reasons above are enough reason to question Active SETI.
 
http://www.seti.org/seti/seti-background/arecibo.php

That'll do for starters. They sent that one to a large bright group of stars that happened to be in the sky at that time; no intent to communicate, but it's a big bright beacon compared to the lost-in-the-background noise of our local transmissions.

Receiving and transmitting antennae are identical. A CB radio, for example, just has a switch on the microphone that lets you turn the receiver off and turn on the transmitter while you have it pushed down. The receiver is turned off to avoid damage, since a strong electrical impulse is required to transmit, but the receiver must be sensitive to weak ones and would be overloaded.
 
See, that's what I'm after. Please, folks, provide links like this when you make claims.

So it seems there's middle ground - it's been done once, maybe a couple more times, but it's not a frequent phenomenon.
 
No, it's more extensive than that. It's been done four times so far, and the other three were to likely stars in our near neighborhood (within 70 light years or so). An effort in 2001 sent a message composed by teenagers in Russia to six nearby stars: http://www.setileague.org/articles/tam.htm

There are people who are less than pleased with this in the scientific community. They have a point. It might not be such a great idea.
 
T-Diddy said:
See, that's what I'm after. Please, folks, provide links like this when you make claims.
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Well, you could have followed the links I posted earlier - post #8 I believe. Specifically David Brin's site has lots of data on this. You could have also googled "Active Seti" as I suggested in the OP. There is lots to be easily found there.

Need to be spoon fed more? How about these:

Seed magazine article "who Speaks for Earth"

Wikipedia's entry on Active SETI

SETILeage article identifies several transmissions made so far
 
I'll admit, I missed that when I skimmed through the articles, because they're pretty cracked in my opinion.

I'm also skeptical of their claim anyone looking could see the transmission. They say:

"The emission was equivalent to a 20 trillion watt omnidirectional broadcast, and would be detectable by a SETI experiment just about anywhere in the galaxy, assuming a receiving antenna similar in size to Arecibo's."

However, even if you assume they have such a telescope (no trivial assumption), the equivalent power of a 20 trillion watt broadcast means that a planet the size of earth, 1 light year away, would receive less than 3 x 10^-6 watts over the entire surface of the planet. I wouldn't be surprised if Arecibo can detect microwatts, but remember, that's across the entire planet.

For a real telescope at a real distance, that's not detectable. Period.
 
drzeus99 said:
Umm..correct me if I'm wrong, but aren't those powerful radio telescopes (like that at Arecibo) "receivers" that collect information and not "transmitters" that send out information? I've always thought they were use solely as receivers.
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Aricebo, at least, is a radar transmitter, as well. (I was just there a couple of weeks ago)

tsg said:
I think the fear about sending these signals into space is largely unjustified.

For it to be a danger requires:
a) something there to receive it
b) that can interpret it as an intelligent signal,
c) has the ability to get here,
d) cares enough to make the trip,
e) and want to kill us when they do.

If all of that were true, we'd likely have encountered them already.
Click to expand...

Exactly.

I find it hard to believe that aliens would find either value or threat enough to warrant an unfriendly trip.
 
Michael Redman said:
I find it hard to believe that aliens would find either value or threat enough to warrant an unfriendly trip.
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Yep - I tend to agree with you and TD that any intelligence out there would have visited us already if they had the means and desire. Our sending targeted signals is not likely to make any difference. But, there is some slim chance that it will make a difference.

Is there any dispute that the targeted signals being sent are more powerful and by their targeted nature more likely to be noticed?
 
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