How many alien civilizations are there ?

[theSOURCE]

psyche

I wrote a long dissertation as a reply, only to realize after listening to it that most of what I wrote was simply agreeing with what you posted. Here's the short version.

First off, I absolutely agree that programs like the SETI project should continue. I'm of the camp that subscribes to the possibility of not only life, but other civilizations exist in the galaxy, despite the fact that it's only speculation at this point.

One problem I have with SETI, however, is that their search is extremely limited due to the fact that they are listening specifically for radio signals (I may be mistaken, so please correct me if I'm wrong). I would consider that as a good starting point, but there are other much more efficient means of communication, especially for interplanetary and long-range space craft chatting. A laser communication system or one which uses microwaves would be two examples that an alien civilization might employ.

But there's the problem of signal degradation across such long distances that needs to be considered. Even if an alien civilization were to point a laser directly at Earth for the purpose of sending a message, the signal would be weakened considerably by the time it reached us. The signal may drop so close to noise level that even it were detected there would be no way to decipher any information from it.

Also, assuming that panspermia was the "spark" of life on a number of other planets, I see no problem with the possibility of convergent evolution taking place, at least in a biological sense.

What I do have a little trouble with is applying the concept of anthropomorphism to a completely alien intelligent species. Assuming that life on Earth and life on our distant neighbors' planet was the result of panspermia (and also assuming that our shared biochemistry is carbon based), there is still a vast number of environmental variables that would shape the development of that alien species intelligence. There are a number of theories that try to explain how human intelligence evolved, from the need for social relationships to avoiding mating with a diseased person. Link. But ironically, those traits can also be applied to forms of life on Earth that many consider to be operating under instinct alone.

Please bear with me while I speculate a bit. What if an alien species that resembles insects similar to those on Earth developed to the stage where they can construct and utilize advanced communication technology?

Take honeybees for example. Their hives are complex and highly organized social structures. Foragers gather nectar for the colony, workers build the comb and tend to the queen, drones mate with the queen, etc, etc. Now lets say that, for whatever reason, they evolved to the point where they needed to develop advanced technology. These high tech bees then come up with a way to communicate with each other on a planetary scale, using radio signals or other forms of technology. And yet, they would still adhere to their hive societal structure; their "lot in life" to use a quaint phrase. So the chances of deciphering whatever they're communicating to each other would be practically zero.

Yes, their colony would resemble many instances of human society; towns and cities where people work together as a whole for specific ends being the main one. But they would lack the individuality that we humans strive for (while it's true that we all sometimes feel like we're nothing more than drones and workers, we at least have BBQs and the occasional beer to look forward to).

My point is simply that even if and/or when we were to detect an actual, traceable, and perhaps continuous signal from an alien civilization, it's not very likely that they would be anthropomorphic, at least not in the strictest sense.

[bison]

OK. I am not sure what you are inferring to be honest. Unfortunately I agree, and I'd like it to be for the same reasons (that ET scans and only happens to "paint" Earth by accident), although it would be nice to have ET actually try and make contact. But honestly, I have serious doubts about that.

Cheers,

Badeskov

An extraterrestrial radio beam pointing our way by accident, briefly, and a sustained effort to communicate with us are not the only possibilities. A beam that sweeps through all possible angles repeatedly, on a regular schedule, is also worth considering.

The Ohio State University 'wow signal' has been listened for repeatedly since its original reception in 1977. It has not been listened for continuously, for a really substantial length of time. If the appropriate sky position were monitored in this way, something just might be turned up, given enough patience on our part.

A much shorter integration time than that used at OSU would be desirable, as they were only able to confirm a gaussian distribution of energy as the Earth's motion swept the dish past that sky position. Getting the content of whatever might be sent in this way would produce a weaker reading, but might still be adequate, given the reported high strength of the original 'wow signal'.

[keithisco]

Personally... I believe that the Human Race is the only dataset of intelligence to actually use Electro - magnetic radiation as a source of communication

"We" may indeed be the first civilisation to have advanced to this point in EM communications, aquatic intelligence would only use sonar communication,other intelligent life may use Light for communication, or acoustics..

Perhaps we are unique in being "curious", perhaps other civilisations (should they exist with EM communication capabilities) have no interest in communicating with other civilisations,

... perhaps we are "alone"... but does that really matter???

[bison]

Personally... I believe that the Human Race is the only dataset of intelligence to actually use Electro - magnetic radiation as a source of communication

"We" may indeed be the first civilisation to have advanced to this point in EM communications, aquatic intelligence would only use sonar communication,other intelligent life may use Light for communication, or acoustics..

Perhaps we are unique in being "curious", perhaps other civilisations (should they exist with EM communication capabilities) have no interest in communicating with other civilisations,

... perhaps we are "alone"... but does that really matter???

Past instances where the human race thought itself in a unique position have all proven to be mistaken. It was once believed that only humans made and used tools, until it was noticed that Chimpanzees do, too. Even planets were once suspected of being very rare; caused by stars passing each other in space and very nearly colliding. We begin to see now that they are quite common.

We seem to be on far safer ground, in assuming that we are a typical intelligent species, and in a typical situation, neither rare nor unique in many respects.

Of course we will not hear radio signals from those who have not developed them, no matter how intelligent they are otherwise.

Popular opinion and that of most scientists agree in counting the question: 'are we alone'? a very interesting and important one. Finding that we are not alone in the universe would be widely considered a profound discovery.

[MedicTJ]

Come on. There's nobody else out there. It's just us. Think about it. Out of all the BILLIONS of galaxies out there that receive light from, there HAS to have been not only one signal....but BILLIONS of signals. Is someone gonna tell me that we're the only ones that use radio frequencies to communicate?

As soon as SETI turned on, they should have found something....if anything was out there.

[bison]

Come on. There's nobody else out there. It's just us. Think about it. Out of all the BILLIONS of galaxies out there that receive light from, there HAS to have been not only one signal....but BILLIONS of signals. Is someone gonna tell me that we're the only ones that use radio frequencies to communicate?

As soon as SETI turned on, they should have found something....if anything was out there.

When we consider the very many combinations of the correct radio frequency, the correct time, during which we might receive a signal, and the required level of signal sensitivity, it is as if we have dipped a glass full of water out of the ocean, and finding no fish in it, conclude that none exist. The fact that an extraterrestrial signal was not found almost immediately may simply mean that the task of finding such a signal is not an especially easy one. Perhaps this is because the rest of the galaxy is not devoting a large part of its time and resources to the task of communicating with us, on this one small planet. Given the billions of stars in the galaxy, this should not be surprising.

[Space Commander Travis]

Come on. There's nobody else out there. It's just us. Think about it. Out of all the BILLIONS of galaxies out there that receive light from, there HAS to have been not only one signal....but BILLIONS of signals. Is someone gonna tell me that we're the only ones that use radio frequencies to communicate?

As soon as SETI turned on, they should have found something....if anything was out there.

You know that radio signals can only be discerned if they're specifically transmitted at us?; general background chatter or things like radio or TV broadcasts (this was where Carl Sagan was apparently wrong) wouldn't be discernible at interstellar distances. Until we started sending signals out, no one would have thought it worthwhile to transmit anything towards us, unless it was in the manner of a specualtive probing sweep, e.g. the WoW signal.

Edited December 13, 2012 by 747400

[TheMacGuffin]

You know that radio signals can only be discerned if they're specifically transmitted at us?; general background chatter or things like radio or TV broadcasts (this was where Carl Sagan was apparently wrong) wouldn't be discernible at interstellar distances. Until we started sending signals out, no one would have thought it worthwhile to transmit anything towards us, unless it was in the manner of a specualtive probing sweep, e.g. the WoW signal.

I think it would have to be a very powerful transmitter aimed in our general direction for us to be able to pick it up. That's why some people think that the 1977 Wow signal was an answer to the 1977 Arecibo signal. Of course, who was doing the signalling and from where is anybody's guess.

I would not be at all surprised if ET signals might be picked up from something much closer than we imagine.

[Dontlisten2me]

edit

Edited December 14, 2012 by kampz

[Dontlisten2me]

Come on. There's nobody else out there. It's just us. Think about it. Out of all the BILLIONS of galaxies out there that receive light from, there HAS to have been not only one signal....but BILLIONS of signals. Is someone gonna tell me that we're the only ones that use radio frequencies to communicate?

As soon as SETI turned on, they should have found something....if anything was out there.

Why do you believe there are billions of galaxies out there and why should there be intelligent life on it? Because you see pictures? Do believe in wood? I do because we have trees and pictures.

Edited December 14, 2012 by kampz

[Harte]

Come on. There's nobody else out there. It's just us. Think about it. Out of all the BILLIONS of galaxies out there that receive light from, there HAS to have been not only one signal....but BILLIONS of signals. Is someone gonna tell me that we're the only ones that use radio frequencies to communicate?

As soon as SETI turned on, they should have found something....if anything was out there.

Due to signal attenuation, your logic falls completely apart.

We'd be lucky to pick up anything beyond about 10 LY unless it was purposefully sent directly to us.

Any radio signal that could survive intact over much greater distances would require an amount of power that would make it not worth the effort, given (obviously) the time lag. That is, there couldn't be any meaningful communications. i.e. conversations.

Harte

[badeskov]

Due to signal attenuation, your logic falls completely apart.

We'd be lucky to pick up anything beyond about 10 LY unless it was purposefully sent directly to us.

Any radio signal that could survive intact over much greater distances would require an amount of power that would make it not worth the effort, given (obviously) the time lag. That is, there couldn't be any meaningful communications. i.e. conversations.

Harte

Harte,

It is very rare that I disagree with you, but here I'd like to offer a correction, albeit a small one. The strongest signals we emit into space are from the Ballistic Missile Early Warning System (BMEWS) radars and with our technology we should be able to detect those emissions out to about 200 LY before they drown in the background noise.

Cheers,

Badeskov

[Harte]

Harte,

It is very rare that I disagree with you, but here I'd like to offer a correction, albeit a small one. The strongest signals we emit into space are from the Ballistic Missile Early Warning System (BMEWS) radars and with our technology we should be able to detect those emissions out to about 200 LY before they drown in the background noise.

Cheers,

Badeskov

Okay. Knowing you, I'll take your word on that.

But the post I responded to appears to be talking about normal communications.

You see the claim all the time that aliens might have recieved (for example) our television broadcasts. Not long ago there was an internet claim that a nearby star system had responded to the very first radio broadcast!

I'm pointing out that such a belief is fatuous. It ain't gonna happen.

Harte

[bison]

Statements about how far away our signals could be heard in space are based on the capabilities of *our* technology. Given the age of the galaxy, and how much time there has been for other civilizations to develop, there could be races a billion or more years ahead of us, technically speaking. Why should our technical limitations apply to them?

There has been serious scientific discussion abvout the possibility of using the Sun as giant gravitational lens, which could focus interstellar radio waves. This method would enable its users to hear signals of even very modest power from throughout the galaxy.

Edited December 14, 2012 by bison

[Quaentum]

Time must also be taken into account. If a civilizations is say 10,000 years more advanced then us and their first signals were sent 10,000 years ago but their planet is 11,000 LY from ours, then we wouldn't even begin to receive the signals for another thousand years.

[Harte]

Statements about how far away our signals could be heard in space are based on the capabilities of *our* technology. Given the age of the galaxy, and how much time there has been for other civilizations to develop, there could be races a billion or more years ahead of us, technically speaking. Why should our technical limitations apply to them?

Noise to signal ratios are real things and are not amenable to "high technology."

If aliens that far away could dismiss the attenuation of EM waves so easily, they wouldn't be looking for anyone like us anyway.

There has been serious scientific discussion about the possibility of using the Sun as giant gravitational lens, which could focus interstellar radio waves. This method would enable its users to hear signals of even very modest power from throughout the galaxy.

"Serious" scientific discussion?

The method would present plenty of problems, not the least of which would be the inability to focus waves except in a relatively small volume of space, the same distance in every direction. Using gravitational lenses means manipulating gravity, which we can't do. So our lens (the Sun) would be "set" to the same focal length in every direction.

Harte

Edited December 14, 2012 by Harte

[bmk1245]

actually I do, and what you say above actually strengthens my point which seems to have been missed by most (except 747).

Yes 1LY is such a great distance we will not do it in a single lifetime rendering the distance of 1LY impossible right? so what difference is 1000LY to 10000 LY...both impossible in a lifetime? is one more impossible than the other??

[...]

First of all, I assumed we are talking about civilizations bit advanced than ours, i.e. capable of reaching significant ratio v/c (0.8, 0.9, 0.995, etc). That alone would give you a chance to travel long distances in your lifetime (energy requirements, though, are immense... ).

Now 1000LY vs 10000LY. That gives you 100 times bigger volume (disk of Milky Way is ~1000LY thick, so cylinder shape is of better use) to search. Which first civilization would find us, if:

1) civilizations, both 1000LY and 10000LY from us, are on comparable technological level? Best guess - 1000LY;

2) civilization 1000LY from us is far more advanced than civilization 10000LY from us? Best quess - 1000LY;

3) civilization 10000LY from us is far more advanced than civilization 1000LY from us? Best guess - 10000LY (though, how "far" is far?).

I know, thats very simplistic, but chances we would be found by civilization that is not that far from us rather than from Andromeda (just curious, did D.Sereda returned from Andromeda, or he's still building "galactic clock spaceship"?) are better.

[...]can I swim 1000 miles under water? is it less likely I can swim 10000 miles under water?

Ah, thats easy, grow the gills...

so something as definitive as 'impossible' you are suggesting has a range..i.e. 'more'??? impossible is impossible I thought...oh well...

I know, kinda optimaler/optimalest than optimal, but "impossible" in 747 post I understood as "impossible to us at the current state".

PS, sorry, 747, I did not replied to you post, since I was waiting for quillius for clarification.

[bison]

Noise to signal ratios are real things and are not amenable to "high technology."

If aliens that far away could dismiss the attenuation of EM waves so easily, they wouldn't be looking for anyone like us anyway.

"Serious" scientific discussion?

The method would present plenty of problems, not the least of which would be the inability to focus waves except in a relatively small volume of space, the same distance in every direction. Using gravitational lenses means manipulating gravity, which we can't do. So our lens (the Sun) would be "set" to the same focal length in every direction.

Harte

Yes, recognized scientists have written quite seriously about the idea. Perhaps the most prominent of these, Dr. Frank Drake. A good, brief outline of the idea is found in chapter 10 of his book: 'Is Anyone Out There'? A space probe could be sent to the distance of the focal point of a star, and moved about at that distance to receive signals from different directions, coming in from the point directly behind the star. An advanced civilization might maintain a number of such probes at the same time, each monitoring targets of interest. Yes the method presents problems from our point of view. It would first be necessary to send a probe out to at least 550 Astronomical units, preferably 1000 AU, and maintain a communications link with it.

[bison]

1000 Astronomical Units is roughly 8 times farther out than our most distant current space probe, Voyager 1. At Voyager's average speed it would take close to three centuries to reach 1000 AU. It would then be between 11 and 12 light days out. Its signal would be just under 2% as strong as that of Voyager is currently. Even if the probe was not maneuverable, if it were in orbit of the Sun it would slowly sweep across the focal point of various stars, at points directly opposite the Sun from its position.

Edited December 14, 2012 by bison

[badeskov]

Okay. Knowing you, I'll take your word on that.

But the post I responded to appears to be talking about normal communications.

I saw that afterwards, I apologize. I was in the lab on my phone, so maybe a little fast on the keyboard. However, normal communications could fall under the same umbrella was one to use a directional antenna and point it somewhere into space.

You see the claim all the time that aliens might have recieved (for example) our television broadcasts. Not long ago there was an internet claim that a nearby star system had responded to the very first radio broadcast!

That I completely agree with. The notion is utterly ludicrous. Nobody is going to respond to the Lucy broadcasts or what have you. And I have to make a small correction again. Detecting our broadcasts with technology we currently have and can envision in the near future would be possible maybe outside of our solar system, not much futher thanks to the omnidirectivity of the antennas used.

I'm pointing out that such a belief is fatuous. It ain't gonna happen.

Nope!

Cheers,

Badeskov

Edited to add a small blurp I wrote about this some years back.

Edited December 15, 2012 by badeskov

[Harte]

Yes, recognized scientists have written quite seriously about the idea. Perhaps the most prominent of these, Dr. Frank Drake. A good, brief outline of the idea is found in chapter 10 of his book: 'Is Anyone Out There'? A space probe could be sent to the distance of the focal point of a star, and moved about at that distance to receive signals from different directions, coming in from the point directly behind the star.

Imagine the distances such a probe would have to traverse in order to make the slightest difference in the direction to be scrutinized.

The vast distances to stars precludes much looking around using this method - assuming current limits on attainable velocities remain in force. On the other hand, any given position in the galaxy has the potential to "monitor" certain areas in various different directions simultaneously, considering that stars surround all interior positions in the galaxy.

I think that for the forseeable future, manufactured telescopes of different variety will provide more info than any gravitational methods.

Harte

[bison]

Imagine the distances such a probe would have to traverse in order to make the slightest difference in the direction to be scrutinized.

The vast distances to stars precludes much looking around using this method - assuming current limits on attainable velocities remain in force. On the other hand, any given position in the galaxy has the potential to "monitor" certain areas in various different directions simultaneously, considering that stars surround all interior positions in the galaxy.

I think that for the forseeable future, manufactured telescopes of different variety will provide more info than any gravitational methods.

Harte

Granted, we probably won't be using this method ourselves, any time soon. The discussion was originally about how far away our own signals could be heard by others. These others might consider even a look at a limited area of space to be worthwhile. Our own Kepler Space Telescope, looking for indications of extra-solar planets, can only examine a small patch of the sky. It has already detected many interesting planets, even with this limitation.

[Harte]

Granted, we probably won't be using this method ourselves, any time soon. The discussion was originally about how far away our own signals could be heard by others. These others might consider even a look at a limited area of space to be worthwhile. Our own Kepler Space Telescope, looking for indications of extra-solar planets, can only examine a small patch of the sky. It has already detected many interesting planets, even with this limitation.

Yes, and aliens could detect planets like Jupiter, and possibly Earth, in this same way.

What do you suggest, then? Should we all jump up and wave?

Without a directed signal aimed at them from Earth, the odds that signals from Earth could be recieved by other life forms at such distances are... wait for it,

Astronomical! LOL

Really. It ain't gonna happen.

Harte

[Kludge808]

Edited to add a small blurp I wrote about this some years back.

Bade, you keep aiming me toward cool threads like this and I may have to make you my UM Guide. ;-)

By the way, does all this discussion mean the voices from the Mothership hiding in the Kuiper belt - or maybe the scattered disk, I never could get where right - might not be from there at all? Darn!

[badeskov]

Bade, you keep aiming me toward cool threads like this and I may have to make you my UM Guide. ;-)

Kludge, old buddy...happy that you like it I am flattered, but I think there are much better guides than me - these days I am mostly lurking due to severe time constraints.

Cheers,

Badeskov