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John D AnthonyProject Donor

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Message 1722858 - Posted: 6 Sep 2015, 18:01:03 UTC

There's something I'm having trouble understanding here. All this crunching helps to figure out which signals are the best candidates for reobservation, but the first two parameters for selection to the short list are association to a known planet or a known star.
Do we really think advanced civilizations would communicate with each other, or with us, using direct, line-of-sight planet to planet signaling like semaphore flags on an open sea?
I'm skeptical of any assumptions made about ETI, but it seems absurd to me that they wouldn't build and use physical networks to facilitate communication across the distances involved. Relays, repeaters, something that would pick up a signal and boost it and send it on, and we wouldn't find those close to any star or known planet - they would be out in the relative quiet between the stars. The signals they transmit would have similarities that could be screened for.
FTL travel and galactic empires don't work for me. I believe in relativity, and that means most, if not all, ETI would be isolated to their home systems. Communication is all they would have, and I'm fairly certain that any life, including life that has evolved beyond biology, would still need a system of some kind to make communication practical.
But if we're only going to relisten to stars and planets we may never hear it.
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Profile Bob DeWoody
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Message 1722908 - Posted: 6 Sep 2015, 20:51:42 UTC - in response to Message 1722858.  

Most likely you are right. Unless ET is sending out very powerful omni directional signals with the intent of finding us we will never pull a meaningful signal out of the noise. But it doesn't hurt to listen. I also feel that if ET has detected us and determined our ways they will never intentionally send a signal our way.
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Michael Watson

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Message 1722919 - Posted: 6 Sep 2015, 21:12:29 UTC
Last modified: 6 Sep 2015, 21:16:12 UTC

There could be an interstellar communications infrastructure, such as you describe. Unfortunately, we have no way of knowing where the relay stations would be located. We can't, in this instance, specify sites that should be given special attention.
It also occurs to me that to work effectively, such relay stations would need to be about midway between the sender, and the intended receiver. Doesn't that imply the ability to travel stellar distances in practical lengths of time? How else could the relays be placed among the stars?
Relativity theory prohibits conventional travel through space at speeds exceeding that of light. It does not seem to forbid the alteration of the structure of space-time, so that space moves around a vessel, and is compressed in the direction of travel. This could provide effective velocities much greater than that of light, while leaving the light speed limit of relativity theory intact.
Of course, if such travel were possible, conventional radio signaling would seem hopelessly slow, by comparison. It might be possible to send a radio message inside an envelope of warped space, at effective speeds much greater than that of light. Perhaps it could be arranged so that the space warp collapses once it reaches its destination, releasing the message for detection by ordinary receivers.
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rob smithProject Donor
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Message 1722920 - Posted: 6 Sep 2015, 21:16:08 UTC

Even if we were the "subject" of a signal aim directly at us it is highly unlikely that we would be able to decode it, and that given interstellar distances it is highly probable that the sender would have shuffled of the mortal coil by the time our response got back. What we are looking for is a sort of "wrong type of white noise" due to the unintentional radio emissions that accompany what we perceive as a sign of civilisation, and something the population of this planet has been doing for just over one hundred years.
Bob Smith
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Somewhere in the (un)known Universe?
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John D AnthonyProject Donor

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Message 1722942 - Posted: 6 Sep 2015, 22:31:49 UTC - in response to Message 1722919.  

I don't believe it implies interstellar travel capability because we've already done it - with the Pioneer and Voyager probes. We know where they'll be in hundreds or thousands of years. Sending out relays would take time but would require minimal effort beyond simple patience.
As I said, we may be able to identify and locate them by a common pattern or form in their signal, but not if we're not looking for it. An identical rate of drift, perhaps, something that wouldn't otherwise stand out unless you screened for it.[/code]
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Message 1722946 - Posted: 6 Sep 2015, 22:37:02 UTC

Galaxies teeming with intelligent life, all slyly eavesdropping on one another? :-)
We have nothing to fear but fear itself. Apart from pain. And maybe humiliation. And obviously death. And failure. But apart from fear, pain and humiliation, failure and the unknown and death - we have nothing to fear. Who’s with me?
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John D AnthonyProject Donor

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Message 1722950 - Posted: 6 Sep 2015, 22:44:03 UTC - in response to Message 1722920.  

At this stage I don't care about decoding or replying - all I'm interested in is a verifiable signal of any kind.
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John D AnthonyProject Donor

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Message 1722962 - Posted: 6 Sep 2015, 23:17:28 UTC - in response to Message 1722908.  

Evolution - as we know it - is a nasty business, but it's hard to conceive of another way that one species is going to get to the top of the chain on another world and have the drive to keep going.
I think it more likely that an ETI detecting and determining our ways would see themselves at an earlier stage of development.
In a relative universe it's not like they have anything to fear from us apart from the noise we make.
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Message 1722964 - Posted: 6 Sep 2015, 23:19:44 UTC
Last modified: 6 Sep 2015, 23:34:21 UTC

http://s591.photobucket.com/user/mittbilde32/media/Clipboard04_zpszwuxnzmx.jpg.html?o=0

Or possibly it is something like this.

It is supposed to be a masked Sirius (alpha Canis Majoris) at the bottom, but next I always thought I was seeing the Arecibo radio telescope floating in space.

For orders sake, I do not like to speculate about such things either.

I did not get any answers to this question here either, for that matter.

For now unable to edit the filename there.

Getting back to it.

Edit: Tried logging out of my Photobucket account, in order to see how things would be looking, but did not find the button.

Instead added /logout to the main address for that server and it worked.

Even there you may be able to see a couple of things, but for now I do not keep much worse than this there.
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Michael Watson

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Message 1722979 - Posted: 7 Sep 2015, 1:02:31 UTC - in response to Message 1722942.  
Last modified: 7 Sep 2015, 1:03:11 UTC

An interstellar radio relay station with a mechanism that could continue to work unattended for at least tens of thousands of years? That does not sound like a minimal effort. It would be something like an autonomous, self- maintaing Von Neuman machine.
What about a power source that would continue to work for that long? If it's to hold station in the voids between the stars, even stellar energy would be negligible.
It might well make more sense to place such relays in fairly close orbits of stars, but then the movements relative to Earth, and the doppler shifts of the signal would be of the same sort as ones from a planet orbiting that star. Nothing particularly distinctive about that.
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Message 1722982 - Posted: 7 Sep 2015, 1:07:36 UTC

My take on this.

You have no idea what works until you do what does not work. I don't think what we are doing at this time works but it is worth the effort to do it. Trial and error is what science is all about. At this early stage of looking for ET we are but barely crawling most likely creeping if that. Lets say you want to want to run a marathon but your 9 months old, gonna take a few more years. That is where I see us. Not even taking baby steps in the marathon to find ET. If that baby never starts crawling it will never do the marathon. You gotta start somewhere.

Hang around for another 5, 20, 50 or 100 years and I think it is very doable. I don't think I have enough years in my lifetime but by doing my small part others will stand on my shoulders.

My 2 cents
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John D AnthonyProject Donor

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Message 1723012 - Posted: 7 Sep 2015, 3:26:26 UTC - in response to Message 1722982.  

The scientific method is all we've got, but at this point I'm not too sure we've got 100 years to play with.
I'm hoping the Breakthrough Initiative means we're finally getting serious about it. Our abilities to search are growing exponentially along with the rest of technology but they have to be applied to be perfected.
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John D AnthonyProject Donor

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Message 1723018 - Posted: 7 Sep 2015, 3:58:56 UTC - in response to Message 1722979.  

People are seriously talking about looking for heat signatures of Dyson spheres and we can't envision autonomous machines?
A relay using nuclear fuel could operate for a very long time and wouldn't necessarily need to be parked to be used for boosting signals. Compared to light speed it would barely be moving. Throw another one in the same direction a hundred years later and you've got the start of an expanding network.
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Message 1723030 - Posted: 7 Sep 2015, 4:47:35 UTC

Mr Anthony, if as you say you believe no one will be able to get around the speed of light then the communication capability we already have will be sufficient to stay in touch throughout our solar system. So unless two civilizations emerge around stars that are only one or two light years apart there may be no need to build transmitters that can be detected at the ranges we need to find ET.

So in effect we are listening on the off chance that a stray signal is directed our way. It is much more likely we will find ET by analysing the chemical composition of candidate planets. What we will do if and when such a planet is found is beyond me. For a long time it will have to be enough that we know they are out there but beyond our capability to communicate with.

Typical scenario: Send a message to a star 50 ly away. Maybe 110-150 years later a reply is received, then it would take another 10-50 years to compose our response etc, etc, etc. And that's assuming we and they decide they want to communicate at all. Not very inspiring.
Bob DeWoody

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Message 1723074 - Posted: 7 Sep 2015, 8:10:50 UTC

I think talking about replies is putting the cart before the horse Bob. Lets worry about detecting any signal, be that 10LY or 500LY. The act of detection is 90 percent of the battle. I don't think a dialog is very viable unless the message instructs us how to communicate FTL. You never know.

First steps first. Find The Signal. Worry about everything else after.

Bob
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Message 1723092 - Posted: 7 Sep 2015, 9:48:55 UTC - in response to Message 1722858.  

There's something I'm having trouble understanding here. All this crunching helps to figure out which signals are the best candidates for reobservation, but the first two parameters for selection to the short list are association to a known planet or a known star.
Do we really think advanced civilizations would communicate with each other, or with us, using direct, line-of-sight planet to planet signaling like semaphore flags on an open sea?
I'm skeptical of any assumptions made about ETI, but it seems absurd to me that they wouldn't build and use physical networks to facilitate communication across the distances involved. Relays, repeaters, something that would pick up a signal and boost it and send it on, and we wouldn't find those close to any star or known planet - they would be out in the relative quiet between the stars. The signals they transmit would have similarities that could be screened for.
FTL travel and galactic empires don't work for me. I believe in relativity, and that means most, if not all, ETI would be isolated to their home systems. Communication is all they would have, and I'm fairly certain that any life, including life that has evolved beyond biology, would still need a system of some kind to make communication practical.
But if we're only going to relisten to stars and planets we may never hear it.

well, yes...we could hear those...but all signals which r candidates get checked also...even if there r no stars...

famous example: WoW signal came out of NOWHERE...didn't repeat it & we send a message back...
did it pick up? :/

so, if we can & find a signal of that sort...we could ease drop!
unless they use "subspace" signals, so it's out of our technological reach...
;)

non-profit org. Play4Life in Zagreb, Croatia, EU
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Message 1723132 - Posted: 7 Sep 2015, 14:27:10 UTC - in response to Message 1723018.  
Last modified: 7 Sep 2015, 14:43:11 UTC

I entertain some serious doubts about nuclear reactors that can operate for tens of thousands of years without refueling, or the need to resort to such measures to power an interstellar communications relay, given access to stellar radiation at close range.
We know so little of the practical details of setting up such a communications system that it's not really possible to say with confidence what would and wouldn't work.
It appears that a relay station, traveling at speeds on the order of several miles per second would emit signals with doppler shifts resembling those from objects gravitationally bound to a star.
In any case, welcome to SETI @ Home and its forum, Mr. Anthony.
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Message 1723179 - Posted: 7 Sep 2015, 16:15:19 UTC

All this crunching helps to figure out which signals are the best candidates for reobservation, but the first two parameters for selection to the short list are association to a known planet or a known star.
Do we really think advanced civilizations would communicate with each other, or with us, using direct, line-of-sight planet to planet signaling like semaphore flags on an open sea?
I'm skeptical of any assumptions made about ETI, but it seems absurd to me that they wouldn't build and use physical networks to facilitate communication across the distances involved. Relays, repeaters, something that would pick up a signal and boost it and send it on, and we wouldn't find those close to any star or known planet - they would be out in the relative quiet between the stars.



I didn't think the candidate signals had to be near anything.


What we are looking for is a sort of "wrong type of white noise" due to the unintentional radio emissions that accompany what we perceive as a sign of civilisation


That's what I thought, and that could mean smack dab in the middle of nowhere, not in a planetary system, right?
The mind is a weird and mysterious place
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Message 1723199 - Posted: 7 Sep 2015, 16:42:06 UTC - in response to Message 1723179.  

I'm referring to an article on the SETI@HOME site titled "Identifying SETI@HOME'S Best Signal Candidates For Reobservation".

It reads, "We consider a candidate exceptional if it exhibits one or more of the following characteristics:
Its location matches the location of a known star.
Its location matches the location of a known planet.
Its barycentric frequency is constant across time but cannot be attributed to RFI.
Matching up a candidate to a specific planet or star is like obtaining a return address. We want to examine these instances first before delving into candidates that don't have an obvious possible source."
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Message 1723266 - Posted: 7 Sep 2015, 18:50:25 UTC - in response to Message 1723132.  

I entertain some serious doubts about nuclear reactors that can operate for tens of thousands of years without refueling, or the need to resort to such measures to power an interstellar communications relay, given access to stellar radiation at close range.
We know so little of the practical details of setting up such a communications system that it's not really possible to say with confidence what would and wouldn't work.
It appears that a relay station, traveling at speeds on the order of several miles per second would emit signals with doppler shifts resembling those from objects gravitationally bound to a star.
In any case, welcome to SETI @ Home and its forum, Mr. Anthony.


The only thing we can say with confidence is that any ETI out there had to start with the same tools we did - the same elements. We can speculate that most encountered many of the same limitations and problems with technology we face and still be on fairly solid ground, as well.
I'm interested in the question of communication technology because it's something we know a little about, and speculation about how we might overcome the problems of setting up an interstellar network could produce clues that would help us detect one if it exists.
When I watch that cloud of signals fill up the box over and over I can't help but wonder if there are patterns in there that we don't see because we're not looking for them or don't have the computing power to make them stand out.
And when I look at the mountain of signal data we've accumulated over the last 50 years my gut tells me we've already heard them.
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