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Bobunf
2004-Aug-08, 05:16 PM
The probability of finding a civilization within a century of our development is extremely small. A model most favorable to civilizations close to us in development might constrain the period in which such civilization could arise to 200 million years. Dealing only with our galaxy for the moment, such a model might stipulate a million civilizations with radio technology.

Assuming an even distribution of these civilizations across the 200 million year time span, there would be only one civilization within three centuries of our development—us and one other. There would be only five within a thousand years. To put it in other terms, 99.9995% of the civi-lization would be more than one thousand years ahead of us.

If the time span in which radio technology civilizations could arise were greater than 200 million years, or, if the number of civilizations were less than a million (both of which seem very likely), the number of such civilizations would fall. At a billion years and a thousand civilizations, for instance, 100% of the civilization would be more than one million years ahead of us.

One way around this would be to constrain the life span of a technological civilization. But such an effort would produce the effect of reducing the number of such civilizations existing at any given point in time. I don't think such an adjustment is relevant to this analysis, since it wouldn't change the number of civilizations that are no more advanced than us.

In the next decade we may begin analyzing the atmospheric gases of extra-solar terrestrial type planets within 50 light years or so of Earth. By looking for water vapor and ozone we will get some very good ideas of the existence of life on these planets. Imagine what we’ll be capable of in a 100 years, let alone a thousand: detection of freon, direct imaging of the planets, uses of lead, isotopic and other analyses to determine energy sources, agricultural activity and industrial processes, and lots of things I haven’t thought of, and probably many things nobody has thought of yet.

To put it another way, doesn’t it seem very likely that nearly all of these 1000 advanced civilizations in the galaxy will know there is life here on Earth? And life using photosynthesis? A signal that's been broadcast from Earth for two billion years. Depending on how close they are, they will know something about the agricultural revolution, metal working, the industrial revolution, the use of refrigerants and nuclear processes, and, perhaps, a lot more. As well as radio and television. If super-luminal communication is possible, it won’t matter how close they are.

When we, for the first time, discover an extra-solar planet with photosynthesis, doesn’t it seem awfully likely that we will study that planet very closely for a very extended period of time? And, a few centuries from now, what about a flyby? An orbiter? A lander? Think of how advanced computers will be by then; and the software, even the hardware, can be continuously up-dated to take advantage of technological advances on the way, albeit with an increasing delay.

If we will be able to do this analysis and initiate this type of mission, doesn’t it seem likely that at least some of these advanced civilizations would do similar things?

Bob

ulgah
2004-Aug-24, 03:12 AM
Bob,
You may be overly optimistic. Living things have existed on Earth almost from the beginning, but multicellular animal life did not appear until about 700 million years ago. For more than three billion years, Earth was inhabited solely by single-celled microorganisms. This time lag seems to imply that the evolution of anything more complicated than a single cell is unlikely. Thus, the transition to multi celled animals might occur on only a tiny fraction of the millions of planets that are inhabited by single-celled organisms.

It could be argued that the long solitude of the bacteria was simply a necessary precursor to the eventual appearance of animal life on Earth. Perhaps it took this long--and will take a comparable length of time on other inhabited planets--for bacterial photosynthesis to produce the quantities of atmospheric oxygen required by more complex forms of life. But even if multi celled life-forms do eventually arise on all life-bearing planets, it still does not follow that these will inevitably lead to intelligent creatures, still less to technological civilizations. As pointed out by Stephen Jay Gould in his book "Wonderful Life," the evolution of intelligent life depends on a host of essentially random environmental influences.

This contingency is illustrated most clearly by the fate of the dinosaurs. They dominated this planet for 140 million years yet never developed a technological civilization. Without their extinction, the result of a chance event, evolutionary history would have been very different. The evolution of intelligent life on Earth has rested on a large number of chance events, at least some of which had a very low probability. In 1983 physicist Brandon Carter concluded that "civilizations comparable with our own are likely to be exceedingly rare, even if locations as favorable as our own are of common occurrence in the galaxy." :)

GOURDHEAD
2004-Aug-24, 03:34 AM
If we will be able to do this analysis and initiate this type of mission, doesn’t it seem likely that at least some of these advanced civilizations would do similar things?

Yes! If there are civilizations advanced to where we'll be 1000 years, they would very likely be detectable by the levels of energy they would be using; at least those within 500 light years of us. Since we haven't noticed them, I choose to believe we are among the more advanced in the MW...at least in this section.

The recent "discovery" that the MW is 13.6 billion years old may mean we're near the top of advancement in the entire universe. Remember it took a while for enough CHON to be spread about in the universe for living organisms to self organize.

zephyr46
2004-Aug-24, 05:22 AM
I have always though looking to globular clusters for advanced civilisation would be the natural thing to do, or the central bulge, areas of much older stars. Also, binary systems, Alpha centauri for instance, has a separation of about 23au, a distance easily traversed by probes, and I guess, life forms.

But yes, such distances, we would need something like tachyon communications , or subspace (whatever that is) or we will face eight year round conversations with theoretical beings on our nearest star system, it only gets worse the further you go.

I have been interested in the radio/TV footprint of our society, nearly a 100 lys is it?? I get real worried when I think about the consequences if a paranoid military/religious/ compulsively economic society picks up on us and has to meet us and sell us cars or paintings or beauty products, or convert us to some bizarre monotheistic religion.

There is a scientific quandary about the observer and subject /cause and effect, study effecting subject?

Relating to a different society is an experience, homogenising it is real risk. It is happening on earth now. Do we really want to travel four light years to drink coke and eat at Taco Bell?

Do we have to try and evolve a middle language that communicates both civilisations beliefs without subjugating the others? Nobel idea? We haven't managed it here amongst ourselves yet!

Typical greeny I guess, worrying about things that we can do very little about.

Bobunf
2004-Aug-24, 05:41 AM
Ulgah, you said to me, “You may be overly optimistic…”

Actually, I’m not optimistic in these maters at all. I put three things together:

A civilization just a little more advanced than us would easily be aware of our existence.
It could easily and very obviously communicate with us.
No evidence of life of any kind outside the solar has ever been seen

These observations, I think, lead to the conclusion that advanced civilizations must be very, very rare, if they exist at all.

Life has been broadcasting it’s signal of water vapor, methane, chlorophyll and ozone for billions of years. Agriculture for thousands of years. Industrialization for centuries.

The longer nothing is noticed the more I feel the number of civilizations more advanced than our own is dwindling towards zero.

I think we may be it. Period. What a monstrous responsibility.

Bob

eburacum45
2004-Aug-24, 05:47 AM
It's no good looking for civilisations in globular clusters-there are probably not enough stable planetary orbits in a globular cluster.

Tachyons would not work as interstellar communication carriers, by the way, as they are causally-reversed; that is they travel from the future to the past. All you would get would be messages from the people of the future talking backwards.

To detect radio and television signals at more than 50 light years would take gigantic radio telescopes many kilometers across; I suppose that there could be adavnced civilisations out there that would have built massive radio telescopes as a hobby...

As far as advanced civilisations go, one thing is mathematically very likely; they will almost certainly not be on the same developmental level as ourselves.
Humans spent hundreds of thousands of years in the palaeolithic age, we have had cities for ten thousand years, a technological society for perhaps three hundred;

if civilisation persists for hundreds of thousands of years, we have only one chance in perhaps a thousand of meeting a race at our level. If civilisations last longer we will have almost no chance of meeting our equals.

ulgah
2004-Aug-24, 11:53 PM
Originally posted by Bobunf@Aug 24 2004, 05:41 AM

These observations, I think, lead to the conclusion that advanced civilizations must be very, very rare, if they exist at all.


Bob,
Well said. Been reading some of your other posts, I think your beliefs are about the same as mine. As a young man, in my 20’s, I imagined many civilizations, and all UFO’s were Flying Saucers, here to save us from our folly. But something strange happened since then. “The more I learn about the cosmos, the less likely it appears, to me, that there are intelligent, technological civilizations out there!!”
:)

ASEI
2004-Aug-25, 02:29 AM
When we, for the first time, discover an extra-solar planet with photosynthesis, doesn’t it seem awfully likely that we will study that planet very closely for a very extended period of time? And, a few centuries from now, what about a flyby?

Maybe we'll find a few million and not know where to start. The sun is a common star type after all...


Yes! If there are civilizations advanced to where we'll be 1000 years, they would very likely be detectable by the levels of energy they would be using; at least those within 500 light years of us. Since we haven't noticed them, I choose to believe we are among the more advanced in the MW...at least in this section.

Not all energy produced is bled off in the form of radio waves. 100,000 GW of electricity turned to heat, turned to infra-red would not even make a visible dent against the light of the star such a planet would orbit.


A civilization just a little more advanced than us would easily be aware of our existence.


Not if they were more than 200 ly away. If they were, mankind would be emmitting nothing. They would be indistinguishible from the broad based fact that there is life here, due to the fact that our largest, most energetic constructions were nothing more than rearrangements of rock and a bit of iron thrown here and there. Low power fires that wouldn't increase the energy put out of the atmosphere one iota.

Plat
2004-Aug-25, 02:52 AM
ASEI, check your Private Messages

Bobunf
2004-Aug-25, 04:18 AM
Ulgah, you said, “The more I learn about the cosmos, the less likely it appears, to me, that there are intelligent, technological civilizations out there!!””

My opinion, that technological civilizations more advanced than our own must be very rare, came as a consequence of observing, over the last decade or so, what has been and will be accomplished with astronomical observations of star systems.

At the beginning of the 21st century, we’re on the verge of being able to determine the existence of life and of industrial civilizations within a few dozen light years of Earth. And this has been accomplished with comparatively little effort, and with few motives beside curiosity. Just think of what we will be capable in the 22nd century.

Advanced ETs would know we are here, would easily be able to contact us, and I find the various ideas as to why they might not contact us very much lacking in merit. I also didn’t credit the idea that these civilizations will be short-lived. I don’t think there’s any evidence at all for this assertion, and it ignores our own experience, and the existence of many hyper-stabilizing strategies, such as the use of independently operating advanced computers, or very extended life spans.

This lack of advanced civilizations is a little surprising considering the probable ubiquity of planetary systems, but every day that goes by without contact raises the probability that contact will not be made this century, if ever. If contact is made in the 22nd century, I think that’s likely to be completely irrelevant to any of us.

So, I guess Proxmire was right about SETI.

And Fermi was certainly right to ask, “Where are they?”

Bob

Bobunf
2004-Aug-25, 05:05 AM
ASEI, you said, “Not if they were more than 200 ly away.”

You establish several limitations for our hypothetical advanced ETs, some of which would probably not hold.

That super-luminal communication, or at least observation, is not possible.

That pre-17th century human activities would leave no trace which ET would be capable of detecting. Activities such as planet-wide agriculture for the last five thousand years, including both flora and fauna, re-shaping and regularizing the landscape and the vegetation patterns, irrigation with its attendant canals (In 1100 AD there were over a thousand miles of canals averaging four meters in cross-section in Maricopa County, Arizona), forest and grass land burning

There was also planet-wide architecture (such as the pyramids and the Great Wall); widespread metal, glass and clay working, the use of lead, arsenic and zinc. Such metal use produced pollution five thousand years ago in parts of what is now Italy to such an extent that health effects can be observed in fossils.

You assume no detection methods for changes in reflective or other indices from the agriculture, burning, deforestation, irrigation, architecture, slight changes or traces in atmosphereic gasses and other elements of civilization. No detection methods for human effects on the whole ecology of the Earth, which have been profound over at least the last five thousand years.

That there’s no way for ET to directly detect intellectual activity, such as language and other forms of symbol manipulation.

I’m sure others, and especially advanced ET, will think of lots of other ways to skin this cat.

I don't think I'd wite off their abilities so easily. What would a super Tri-corder detect at a distance?

Bob

ASEI
2004-Aug-25, 01:13 PM
Assuming that I'm an advanced ET pointing a telescope at earth, and that I have the extremely impressive ability to, say, photograph the continents at a detailed level rather (say resolution of 500 miles) than merely pick up it's generalized spectrum. There wouldn't be any visible continent wide impressions left by medievel humanity. Despite all our impressive effects on the local environment, our footprint was ridiculously small on a planetary scale. The pyramids would be well below the resolution of observation, as would symbols and other grand monuments of our design. The canals would be much too thin for observation, and their only visible evidence, the bloom of primitive agriculture, would probably be indistinguishible from other plant life surrounding it. How would we know which batch of green was natural and which wasn't, if it is all blurred together into a pixellated mass? The only fires and industrial processes that mankind had were feeble compared to natural fires and volcanic emmissions. The composition of the atmosphere would change so very little because of any metal forging, ect that would go on.

Perhaps if they looked hard they could detect modern man, with his unmistakable agricultural footprint and regular emmissions of light and heat when the planet is dark, but for most of the previous eras, our footprint was much much smaller.

Bobunf
2004-Aug-26, 04:23 AM
ASEI,

I think you've listed a lot of limitations from which we will suffer for at least the rest of the 21st century. But I think you underestimate the potential of technology. Two hundred years ago it was understood that the determination of the mineral composition of celestial objects other than Earth would forever be impossible.

A hundred years ago idea would have seemed preposterous that we would in the 21st century, relatively easily, be able to detect methane or oxygen producing life in any star system within a few hundred light years of Earth. The idea of dating fossils with confidence and accuracy through isotope analysis would have made no sense.

Until the mid-20th century, it was understood that significant astronomical observations using any part of the electromagnetic spectrum would be forever impossible except for a very narrow range centered about visible light and some radio frequencies, because of the generally opaque nature of the Earth's atmosphere.

Obviously, I can’t tell you how some new breakthrough technology will enable detection, not necessarily imaging, of the products of intelligence before radio signals. But I feel sure that very clever people will figure out how to tease out the effects large scale agriculture—detecting the diminution of species variation using some polarized isotope spectrum procedure; detecting the deviation from natural meander patterns of large scale irrigation from variations in water vapor spectra; and many, many way out and imaginative techniques.

Let’s not let our imaginations fail us in speculating about the abilities of advanced ET. Instead, I think it would be productive to consider how we would react, even today, if we were aware of a life bearing world 50 light years away.

Bob

zephyr46
2004-Sep-13, 05:45 AM
I said in an earlier post that I thought Globular Clusters would be a good place to look for et, well I am not the first;


Globular cluster M13 was selected in 1974 as target for one of the first radio messages addressed to possible extra-terrestrial intelligent races, and sent by the big radio telescope of the Arecibo Observatory

SEDS, M13 (http://seds.lpl.arizona.edu/messier/m/m013.html)

http://seds.lpl.arizona.edu/messier/Pics/More/m13msg_s.jpg


Of course, this message will take about 23,000 years to reach the cluster, so that an answer cannot be expected for 46,000 years !

http://seds.lpl.arizona.edu/messier/more/m013_msg.html

Sounds like it might be quicker to go to Proxima :D