If we had an identical twin civilization in our galaxy, and Arecibo was pointing right at them (putting aside the issue of how long it would take signals to get here) would we find them? Would our search methods find our own civilization? If not, that would seem like a rather sizeable flaw. It would be like failing to see a person there when you looked in the mirror. Unless you're a vampire, that would suggest a problem.

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If they were located within about a 20 light year radius of us, then yes, we would be capable of finding them.

Our galaxy however, has a diameter of 100,000+ light years.

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www.onlinetasklist.com

Question is... would we want to find ourselves?... Nasty little critters..

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... within about a 20 light year radius of us, then yes ...

The signal stregnth is too weak beyond 20LY? Any way to overcome that short of building a bigger dish?

would we want to find ourselves?

Yes

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Any way to overcome that short of building a bigger dish?

Nope, have to build a bigger dish. We are working on it though.

Allen Telescope

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www.onlinetasklist.com

Even if ET is sending signals to us, it would take X years to get here, given that ET is X light years away.

For instance, for 300 light-years away, it would take 300 years to get to us...

How close is the nearest star?

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How close is the nearest star?

The smart-arse answer is 93 million miles, the star next being about 4 light years away.

Seriously though, when considering if we could find ourselves, we need to take into consideration the search techniques currently employed. Radio Seti is predominantly based on searching for narrow bandwidth signals at a very special part of the spectrum (the resonant frequency of Hydrogen, if I remember correctly).

This implies that we search for a beacon, rather than overspill of broadband chatter that we currently leak into space.

Also consider the effective radiated power off beam from all this chatter. This will be very much smaller, by several orders of magnitude, than a focussed transmission. Take for example the low power focussed narrow band signals from early probes such as Pioneer and [edit]Voyager. These have been detectable a few dB above noise, at the edge of the solar system. Compare these to a broadband communications signal, off the focussed beam. Such signals will have much lower detectability when measured in the same narrow bandwidth.

With this in mind, our current Radio Seti techniques are very unlikely to find "us".

However, even though the probability of finding a signal is very small, it is much greater than if we did not search at all.

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[quote]
However, even though the probability of finding a signal is very small, it is much greater than if we did not search at all.

Looking for a focused beam at the hydrogen frequency makes sense as a good place to start. Looking for another civilization that is sending out a beacon would probably find somebody else who is hoping to make contact, rather than stumbling onto who-knows-what. Further, given the limitations of technology and the amount of terrestial noise it seems to be the most efficient way to look. Maybe in the future we can look for any sort of radio leakage from another civilization, but it seems fair to start looking for an intentional trans-civilization signal.

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<a href="http://www.davidcthompson.com">David Thompson</a>, Intellectual Property Law

<a href="http://www.stanford.edu/group/slaps/">Stanford Law and Policy Society</a>

Here's a question - is anyone on earth operating a Hydrogen-Frequency Beacon that ET could detect?

If not, why not?

Also, where would the best place in space be to point said beacon?

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Here's a question - is anyone on earth operating a Hydrogen-Frequency Beacon that ET could detect?

If not, why not?

Also, where would the best place in space be to point said beacon?

I suspect the main reason is (1) money. (2) Some people, such Stephen Hawking, if I'm not mistaken (though a quick google search failed to turn up the quote), fear it might be dangerous to so callously announce our presence. (3) Others have suggested that, dangerous or not, putting up such a beacon is an important decision for humanity to make as a whole, and that it would be immoral for one group to go out and do it on their own. Good luck getting a consensus on that anytime soon!

Looking for an intentional beacon may be a good (and relatively easy) place to start, but it is funny to me how many times I come across statements about what any intelligent civilization would obviously do when our civilization seem to do so few of those obvious things, but maybe we will someday.

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>Here's a question - is anyone on earth operating a Hydrogen-Frequency Beacon that ET could detect?

You beat me to it. I was going to ask the same thing.
As far as I can find there is nobdy transmitting a constant beacon or signal. Since we are not then it would seem strange to assume that others out there are. Maybey those other civilizations out there have the same problem that Vodoo brought up. money and fear.
We did however transmit a message from Arecibo one time. I haven't done the math myself but from what I've read in Boinc and SETI classic forums it was about as fruitless as shooting rubberbands at the stars. The star or solar system that it was aimed at will not be in the location in space when it arrives and it's power will have dwindled so much that it would be very hard to be picked up by equipment equivalent to ours.
Take it for what it's worth. I didn't get this info from any observatories. It is just what I've read in forums. But we did transmit the signal. That is fact. There was also a "crop-circle" made near an observatory that was similar to the transmitted signal with one exception. It listed the lifeform as silicon based instead of carbon based. I thought it was a pretty coll crafted joke.

so, if we, the only intelligent life-forms in the universe (as far as we know) are NOT running a hydrogen beacon, why do we assume others are?

Am I wasting electricity crunching SETI numbers?

Are there other avenues to explore apart from the hydrogen frequency?

Dec.

(As an aside - it would be nice to know if anything has been made of the science of this project - i can't seem to find any results or conclusions about it anywhere)

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Well, we have some solid reasons to be afraid... and the main one is the state mankind is in right now. With such an immense range of often conflicting values and goals it's a miracle that we are still around. It's a safe bet to assume that we are in a pre-civilization period in the eyes of really sophisticated aliens. May be they think that we have to grow up a little on our own before there's any sense in contacting us.
We are not hopeless, of course. After all we do support projects like SETI-BOINC, don't we? :))

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so, if we, the only intelligent life-forms in the universe (as far as we know) are NOT running a hydrogen beacon, why do we assume others are?

Am I wasting electricity crunching SETI numbers?

Are there other avenues to explore apart from the hydrogen frequency?

Dec.

(As an aside - it would be nice to know if anything has been made of the science of this project - i can't seem to find any results or conclusions about it anywhere)

From here... (page 2):

If you point your radio telescope at the sky there are all kinds of signals. Some come from the galaxy itself. Some come from our atmosphere. If you made a diagram of this unavoidable noise, you would notice that it's really noisy at low frequencies because of the galaxy. It also becomes noisy at higher frequencies due to atmospheric noise. Between the two noisy regions you would find a relatively quiet region -- from about 1 GHz to about 10 GHz. (1 GHZ or 1 GigaHertz is 1 billion Hertz or 1 billion vibrations per second. This part of the radio spectrum is just above the part used for your electronic pagers and many wireless phones.)

Nature provides an even nicer way to further refine our frequency range. The simplest "stuff" of the universe, neutral hydrogen gas in interstellar space, emits radio signals at 1.42 GHz. Another molecule in space, the hydroxyl, or OH, emits at about 1.64 GHz. Now if you look at these two, H and OH, you would see that together they make up the compound of water HOH (or more commonly H2O). Life as we know it requires water to evolve and exist. The frequency range between these two emissions, from 1.42 to 1.64 GHz, is therefore a quiet region of the spectrum called "the water hole." Where would you expect water-based intelligent civilizations to meet? Around the water hole, of course! This would be a good, and nicely limited, range of frequencies to start our search. We can always broaden our net at a later date.

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An important fact to note here is that the narrower a signal (the more refined the frequency), the more efficient it is for our friends to send. A narrower frequency signal is also easier for us to pick up above the normal noise level. Unfortunately, very narrow frequency signals mean that we have to look at millions of very narrow frequencies to find just the right one. More on this later.

What kind of signals are we likely to receive? What should we be looking for? There are really two possibilities. Either the other civilizations are intentionally sending out a signal that is expressly meant to get our attention, or, like us, they just happen to be doing their own business and some of their signals are "leaking out." The earth broadcasts lots of stuff unintentionally. Our radio and television transmitters are very strong. Our military radars are even stronger. We've been leaking this stuff for at least 50 years, so our signals are about 50 light-years out. Not very far, but we are still technological infants. It seems like we should try to search for the leakage-type signal and assume that we will also pick up anything that is beamed at us.



We're searching at that frecuency because it's more efficient in terms of noise. As for why we're expecting THEM to transmit when we're not; if there's life out there, then there must be lots of civilizations out there.. chances are one of them are actually transmitting. If there's no life out there, then yes, we'll all just wasting electricity.


Hope this helps... I recommend reading the whole article, it's worth it.

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Am I wasting electricity crunching SETI numbers?

My humble opinion on that score is written in the bottom part of my profile.

Well, I suppose we have to start somewhere. The hydrogen "watering hole" is as likely place to start as any. Where else would be a good place to look?

so, if we, the only intelligent life-forms in the universe (as far as we know) are NOT running a hydrogen beacon, why do we assume others are?

Am I wasting electricity crunching SETI numbers?

Are there other avenues to explore apart from the hydrogen frequency?

Dec.

(As an aside - it would be nice to know if anything has been made of the science of this project - i can't seem to find any results or conclusions about it anywhere)

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