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willstaruss22
2013-Apr-27, 12:26 AM
What is the likely hood of there being advanced civilizations in the Milkyway Galaxy? In my own opinion I believe that there could be hundreds of millions if not a few billion worlds including moons in our galaxy with simple single celled life however I believe that only 1,000-10,000 worlds have intelligent life on them. Is that unreasonable?

cjameshuff
2013-Apr-27, 02:02 AM
What is the likely hood of there being advanced civilizations in the Milkyway Galaxy? In my own opinion I believe that there could be hundreds of millions if not a few billion worlds including moons in our galaxy with simple single celled life however I believe that only 1,000-10,000 worlds have intelligent life on them. Is that unreasonable?

There's really no way to estimate that. We have one known example of a planet with life, intelligence, and a technological civilization. The probability of each of these is obviously something non-zero...the probability of us being alone in the universe is basically zero. The probability of us having a neighbor within any finite region of the universe is something we can only guess at.

I suspect Earthlike life is common. It has been on Earth for essentially as long as Earth could support it. There's many plausible ways for it to have formed, and an entire planetary environment gives a monstrously huge natural laboratory to form it in. If it's unlikely, we were extremely lucky.

I also suspect a lot of those planets never get past single-celled life. It took a long time for Earth to do so, a good 2.6 billion years of its 3.6 billion years as a life-supporting planet. If it took 1 billion years longer, it'd still be stuck with single-celled life. A bit longer than that, and Earth would be sterilized by the sun's red giant stage before developing multicellular life. Evolution doesn't follow a strict schedule, after all.

It has had complex animals with nervous systems that could potentially produce an intelligent species for about 500 million years, and our appearance was certainly not inevitable. When hominids did appear and made rapid increases in intelligence for whatever reason, they weren't the most successful bunch. For about 2.3 million years, they struggled to survive and most hominids went extinct. But in the end, the adaptability of a couple strains made up for their shortcomings.

And then Earth was a planet with intelligent life, essentially modern humans and a couple other surviving hominids...for 200 thousand years, with low, dispersed populations and near-static technology level. We could have gone millions of years without developing civilization, we could have died out at any time, and we very nearly did at least once...there's signs of severe population bottlenecks in the past of Homo sapiens. But a short time ago we went agricultural, started building big civilizations, developed high technology, visited the moon a few times, and are now debating whether it's worth the minor effort to look for anyone else out there.

Not enough data there to make a good estimate of the probability of an advanced civilization appearing on any one world, but I think it indicates it's on the low end. And more likely on cooler stars that live longer, and more likely on larger planets that can maintain life longer...meaning that many might not have any practical way to get off their planet and might not have a very good view of the sky. Or they might consider G-type stars hopelessly short-lived to consider as candidates for intelligent life.

neilzero
2013-Apr-27, 03:40 AM
1000 intelegent planets may be may be a mainstream guesstimate now that we think there may be a million times a million planets in our galaxy. I'd like to think more than one million planets with intelegent life including planets that were colonized. That would only be one in a million of the optimistic number of planets our galaxy may have.
The Pleides are a favorate example. Planets likely pass within a million kilometers about once per century, Allowing colonization of up to 10,000 planets in one million years of spacefareing from a single planet. On the negative side, the Pleides may only have 100 planets, but more seems likely if you count planets that are presently about 100 lightyears from the center, but traveling aproximately toward the center. How many tightly spaced clusters are known in our galaxy? Neil

willstaruss22
2013-Apr-27, 06:32 AM
Yes I agree with most planets and moons having single celled life. For more intelligent life my 1,000-10,000 civilizations is on the conservative side. Yes if an intelligent species were advanced enough I would think they would colonize. We however need to remember that intelligent life would most likely hangs on a delicate balance of conditions to survive.

Zwart Gat
2013-Apr-27, 10:24 AM
I hope that a big break through will happen within the next few years or decades, by increased understanding of how life first formed. Then it'll be possible to make estimations of its frequency. Science can't be too far from nailing that little mystery now. Today we're sadly clueless and without observation there's no good way to guess.

I like one proposed solution to the so called Fermi paradox, why we don't detect any ET. That once a civlization achieves enough economy, it is so satisfied with using the energy of its own star, and maybe a very few neighboring ones, that they stay at home and play with their super computers. If you understand all physics already, then what's the point of traveling far? There's nothing to discover there. It'd just be pointless geography about nowhere, they don't need to use interstellar space anymore. A galaxy of mutually uninterested civilizations, that's a thought.

antoniseb
2013-Apr-27, 12:43 PM
Plugging high and low end reasonable numbers into the Drake equation, and looking at the upper and lower limits you get numbers like 1 (us) to millions, but I think the big limit will be based on how long such a civilization could exist. If it is under 1000 years between having radio and self annihilation, the number will be pretty low.

Ara Pacis
2013-Apr-27, 02:34 PM
Biological evolution is not guaranteed. Escape from cataclysm is not guaranteed. Technological evolution is not guaranteed. The Greeks developed gear-work computers and tested steam engines yet we didn't see them enter production for about two millenia. Perhaps as important as mechanical technology will be the co-evolution of plants and animals suitable to creating a technological civilization. If they don't have farmable plants or animals that can be domesticated for prime movers, transportation and burden, then perhaps they won't do very far and do very much for a very long time.

ASTRO BOY
2013-May-02, 01:07 AM
I hope that a big break through will happen within the next few years or decades, by increased understanding of how life first formed. Then it'll be possible to make estimations of its frequency. Science can't be too far from nailing that little mystery now. Today we're sadly clueless and without observation there's no good way to guess.

I like one proposed solution to the so called Fermi paradox, why we don't detect any ET. That once a civlization achieves enough economy, it is so satisfied with using the energy of its own star, and maybe a very few neighboring ones, that they stay at home and play with their super computers. If you understand all physics already, then what's the point of traveling far? There's nothing to discover there. It'd just be pointless geography about nowhere, they don't need to use interstellar space anymore. A galaxy of mutually uninterested civilizations, that's a thought.



There are many reasons for scientists/Astro-physicists and Cosmologists to logically assume we are not alone.
Why there has been no contact also has many probabilities....
Ourselves, we have barely climbed out of the confines of our Earthly cradle, and detectable raido signals havn't been around that long...Time and distance are the prime reasons.
I would like to add the hypothesis that once civilisations have achieved inter-stellar travel abilities and become "super intelligent" and are able to access all the energy they will ever need, we just may well appear as rather insignificant to them to make contact with us.
And who knows, having super-intelligence I would surmise that they are also peaceful and co-operative....at least I would like to couple those qualities with super-intelligence!
They may even have a galactic type of "prime directive" about contacting ignorant barely intelligent savages such as humans.
Maybe it is also tied up with evolution and species of beings we are yet able to contemplate.

A whole lot of "if's" I know with the only real certainty being that it is a pretty pointless Universe, if we were to be really alone.
Something along with the initiator of this thread I find as hugely unlikely and illogical.

transreality
2013-May-02, 02:25 AM
A problem with the Pleiades and similar tight clusters is that they are quite young, possibly too young for life to have evolved, at least as it did on Earth. The Hyades is an older cluster that is closer to the age required but has already dispersed to the point where travel between the members is no longer convenient.



1000 intelegent planets may be may be a mainstream guesstimate now that we think there may be a million times a million planets in our galaxy. I'd like to think more than one million planets with intelegent life including planets that were colonized. That would only be one in a million of the optimistic number of planets our galaxy may have.
The Pleides are a favorate example. Planets likely pass within a million kilometers about once per century, Allowing colonization of up to 10,000 planets in one million years of spacefareing from a single planet. On the negative side, the Pleides may only have 100 planets, but more seems likely if you count planets that are presently about 100 lightyears from the center, but traveling aproximately toward the center. How many tightly spaced clusters are known in our galaxy? Neil

transreality
2013-May-02, 02:31 AM
I know with the only real certainty being that it is a pretty pointless Universe, if we were to be really alone.
Something along with the initiator of this thread I find as hugely unlikely and illogical.

If the Multiverse hypothesis is accepted that suggests there are many entire universes out there in which life could never arise. Or another way the particular cosmological factors that permit the existance of life, and other complex structures, seem so arbitarily unlikely and so contingent, that is considered to be unlikely that our universe is the only one. That would indicate that the universe is completely and utterly indifferent to our existance.

SphinxCore
2013-May-02, 08:06 PM
Odds are any truly intelligent species / civilizations out in the cosmos as may be aware of us would avoid us simply because humans haven't gotten beyond some very primitive behavior.

Once humanity has learned enough to be able to (a) reach the stars and (b) cooperate enough to actually do so without turning the galactic neighborhood into a cosmic ghetto / war zone then we may get a better understanding of how many civilizations currently exist out there.

Ara Pacis
2013-May-02, 08:42 PM
A whole lot of "if's" I know with the only real certainty being that it is a pretty pointless Universe, if we were to be really alone.
Something along with the initiator of this thread I find as hugely unlikely and illogical.

(emphasis mine)
Pointlessness would seem to be the null hypothesis.

ASTRO BOY
2013-May-02, 09:17 PM
That would indicate that the universe is completely and utterly indifferent to our existance.

My bad wording. The point I'm trying to make is that a Universe with the same extent conditions and numbers that we know of, it would be highly unlikely that we are it.

molesworth
2013-May-03, 12:08 PM
Plugging high and low end reasonable numbers into the Drake equation, and looking at the upper and lower limits you get numbers like 1 (us) to millions, but I think the big limit will be based on how long such a civilization could exist. If it is under 1000 years between having radio and self annihilation, the number will be pretty low.
A more useful or interesting number, at least as far as the Fermi paradox goes, is the length of time a civilisation will be detectable at a distance. I recall reading recently that Earth's broadacsts into space are already reducing in power as we start using more directed methods of communication and improved technology for transmitting and receiving.

If extra-terrestrial civilisations are only detectable for a few hundred years, that may mean our chances of spotting one are extemely remote. Likewise, if anybody out there misses our early broadcasts, they're very likely not going to see the re-runs / repeats (which may be a good thing... :) )

NoChoice
2013-May-05, 12:30 AM
What is the likely hood of there being advanced civilizations in the Milkyway Galaxy? In my own opinion I believe that there could be hundreds of millions if not a few billion worlds including moons in our galaxy with simple single celled life however I believe that only 1,000-10,000 worlds have intelligent life on them. Is that unreasonable?

While I agree with cjameshuff that there really is no way to estimate that, personally I believe this is a rather conservative estimate, given the abundance of stars and potentially habitable planets. The more we learn the more it seems that the prerequisites for intelligent life are quite common in the universe.

NoChoice
2013-May-05, 12:34 AM
I hope that a big break through will happen within the next few years or decades, by increased understanding of how life first formed. Then it'll be possible to make estimations of its frequency. Science can't be too far from nailing that little mystery now. Today we're sadly clueless and without observation there's no good way to guess.

I like one proposed solution to the so called Fermi paradox, why we don't detect any ET. That once a civlization achieves enough economy, it is so satisfied with using the energy of its own star, and maybe a very few neighboring ones, that they stay at home and play with their super computers. If you understand all physics already, then what's the point of traveling far? There's nothing to discover there. It'd just be pointless geography about nowhere, they don't need to use interstellar space anymore. A galaxy of mutually uninterested civilizations, that's a thought.

Not so sure about that. Even frequent travelers on earth do enjoy exploring new places, even close to home. It's that quest for exploration that drives any civilization I would imagine. Even if you've seen it all it is still quite conceivable that some of the beauty we have discovered in the universe provides such an attraction that you wouldn't get tired of seeing it again and again. I'm pretty sure I wouldn't get tired of it. There's music and other art forms that I indulge in again and again because the beauty of it just captures and fascinates me again and again.

NoChoice
2013-May-05, 12:43 AM
(emphasis mine)
Pointlessness would seem to be the null hypothesis.

Personally, I think the universe does not adhere to the concepts we superimpose on it with our little minds.
I believe the universe is beyond meaning, i.e. neither meaningful, nor bereft of meaning. The concept simply doesn't apply. The universe just is.

I believe the same is true for our concepts of time and space. They exist only in our minds and our little minds simply cannot begin to comprehend what is really "out there".
We don't even know what an electron really is. The closer we seem to get the more it slips away and presents us with conundrums (wave/particle duality for example).

We may have mathematical tools to describe them and their behavior, but math does not grasp their essence (whatever that may be) in any comprehensible way.

swampyankee
2013-May-05, 04:22 PM
A more useful or interesting number, at least as far as the Fermi paradox goes, is the length of time a civilisation will be detectable at a distance. I recall reading recently that Earth's broadacsts into space are already reducing in power as we start using more directed methods of communication and improved technology for transmitting and receiving.

If extra-terrestrial civilisations are only detectable for a few hundred years, that may mean our chances of spotting one are extemely remote. Likewise, if anybody out there misses our early broadcasts, they're very likely not going to see the re-runs / repeats (which may be a good thing... :) )

I suspect that technologies like air traffic control radars are much more important to the detectability of a civilization than are radio communications; these are likely to continue for the foreseeable future. They aren't easy to detect, as they are highly directional, and pulsed, as opposed to somewhat omni-directional (broadcast TV and radio are not omni-directional; both use antenna systems which concentrate their output to minimize energy going vertically upward. Not much audience up there) and continuous.

As for detectable broadcasts, they're probably only about 70 years old, not existing before the exploitation of radio frequencies that weren't reflected by the ionosphere, so this puts one hard limit on the size of the detectable radio sphere. I have read that the Earth emits more radio frequency radiation than the Sun, so, if that's correct, it may offer a way for a culture with sufficiently advanced radio telescopes a method to detect Earth, and a spectral analysis of the RF radiation may provide indications that it's not entirely natural. That's a lot of maybe, and it's likely to be very difficult, as it would require something akin to an RF version of Kepler staring at suspect stars.

Hlafordlaes
2013-May-05, 05:02 PM
Personally, I think the universe does not adhere to the concepts we superimpose on it with our little minds.
I believe the universe is beyond meaning, i.e. neither meaningful, nor bereft of meaning. The concept simply doesn't apply. The universe just is.

I believe the same is true for our concepts of time and space. They exist only in our minds and our little minds simply cannot begin to comprehend what is really "out there".
We don't even know what an electron really is. The closer we seem to get the more it slips away and presents us with conundrums (wave/particle duality for example).

We may have mathematical tools to describe them and their behavior, but math does not grasp their essence (whatever that may be) in any comprehensible way.

There seems to be a lot of consensus in many quarters that this is indeed the right take. Yet we all drive our cars like naïve realists, which I find to be a "kicker."

I am tempted to think of the quantum world as an "unreliable" generative substrate that provides a reliable, interactive, cause-and-effect macro space that life inhabits. How? Seems to be very much a work in progress.

I also observe that much confusion comes from changing definitions, not results. Even if the naïve realist's "solid" is actually an EM field and not continuous corpuscular matter, "solid" still operates the same, and we may continue to count on not falling through floors.

Couldn't agree more there is no "meaning" to be sought in the universe. Like a dictionary, all its elements in the end are defined by the others in the system, having no meaning independently of them, and so all definitions become circular.

iquestor
2013-May-05, 06:32 PM
I think detectability of Earthlife from an ET Civ would first be done through Spectroscopy, rather then intercepting EM transmissions which are likely too weak to provide useful data. I dont know if spectroscopy could provide proof of an intelligent civ on Earth, but it should be able to provide proof of a living biosphere.

NoChoice
2013-May-06, 02:16 AM
Even if the naïve realist's "solid" is actually an EM field and not continuous corpuscular matter, "solid" still operates the same, and we may continue to count on not falling through floors.

This is actually a beautiful example of how our minds translate aspects of "reality" into concepts that really have little to do with it and yet somehow "work" (within the invented framework of our mind) for our practical purposes.

As you point out there is really no "solidity" "out there". When you hit a wall it is basically EM fields interacting with each other.
So our concept of "solidity" is invented (and even wrong upon closer inspection) but it does relate to an aspect of "reality" and it works for our practical purposes.

And I believe the same is true for our concepts of time and space. They don't exists in the way our concepts and minds may suggest but they do relate to aspects of "reality" and they work for our practical purposes.


Yet we all drive our cars like naïve realists, which I find to be a "kicker."
Indeed. I agree, this is a "kicker"! :-)
It just shows how internally consistent the illusion invented by our minds is.

Welcome to the dream!

Centaur
2013-May-06, 04:18 AM
I highly doubt there are other technological civilizations in the galaxy. Obviously, some other folks believe (hope, wish) there are. If they want to spend their own money on a fairly scientific research program, so be it. Admittedly, I do benefit from learning about their negative results. On the remote chance that they are right, I would certainly learn something. Our collective resources could probably be invested more wisely, but that could be said about a great many things in a free society.

More than half a century ago when I was eleven I attended a planetarium lecture on the origin, age and future of the universe. At the bus stop going home I got to thinking that even if I lived to be a hundred, the chance of the current moment in the history of the universe also being a moment in my life was pitifully small. While the odds of my being alive at that moment were weak, nevertheless I knew I could only consider the problem during my lifetime. Despite ETI proponents promoting a rather dubious Drake Equation, logic trumps weakly devised probability estimates. Numbers like billions and trillions may dazzle the mind, but they are practically infinitesimal compared with number of possible arrangements of organic molecules for which very few could replicate and become something like DNA. Matter and energy may have had to jump through countless high and tiny hoops to produce mankind. But despite the odds, they obviously succeeded at least once. Although that it no way proves it happened twice or was even likely to have occurred elsewhere. There may be a zillion planets out there, but that does not imply that technological civilizations “must have” evolved on some of them.

Simply to assemble primordial molecules into the simplest DNA or RNA chain capable of reproducing is stupendously unlikely, although it had to happen once. Another planet crashing into early Earth was hugely unlikely, but it was necessary to produce the Moon which stabilizes the Earth’s rotation and produces significant ocean tides. These were necessary for complex life to develop and move to land. It’s highly unusual for a planetary system to include a Jupiter size planet in a low eccentricity orbit and much further from the central star than an earthlike planet, but it’s needed to eat up most rogue comets and asteroids that could destroy life on Earth. Every step leading to the quite recent development of humankind was beyond reasonable expectations. But it happened once despite the odds, and if only once then obviously Earth is the only place in which we could be having this discussion.

We are a result of a process of biological evolution. Genes protect their own kind and destroy those that directly threaten them or compete for resources. The fittest survive. Our own species has engaged in war and genocide right up to the modern era, not to mention what we do to other species. We likely disposed of the Neanderthals and other hominids. Yet we are more closely related to a blade of grass, than to any extraterrestrial, no matter how intelligent it might be.

I would be concerned about the designs of a race of technological extraterrestrials that became aware of our existence. It may be unfortunate, but those who assume (hope, wish) that evolution will eventually lead to harmony and brotherhood among all intelligent creatures are probably kidding themselves. Evolution has no “ultimate purpose”, no goal. Survival is what matters, and its means may not be what some Pollyanna thinks it should be. Yet I submit that it is often Pollyanna who is searching for extraterrestrial intelligence. Polly is relatively harmless as long as she only attempts to receive signals and not send them.

To some the notion that intelligent extraterrestrials would come to guide us, gives them almost religious comfort even if they have abandoned traditional religions. Yet this is a motivation for many SETI people. But would we really want to become like Eloi and have no need to think or provide for ourselves? Would we prefer to have learned the laws of mechanics from ET rather than Galileo and Newton? If ET really came "to serve man”, would we actually be better off? Would life be worth living?

The universe has existed for 13.8 billion years. One percent of one percent of that is 1.38 million years. It’s been estimated that the first technological species in our galaxy would completely colonize it within that period of time. I suspect it is rather unlikely that two intelligent species reached our technological level together in the galaxy within a time span less than that. We are probably either well ahead of whichever species (if any) is in second place, or well behind any other that might be in first place. And if there are tens of thousands of such species in our galaxy, as some ET promoters suggest, at least one of them at one time in its history could easily have had a leader who led a campaign of galactic cleansing. It only had to be done once for our species to be exterminated. I submit that if any species became technological before us, they would have wiped out our ancestors as vermin long ago, and we would not be holding this discussion.

So I would be worried and not pleased if SETI were successful in finding ETI. Yet since our ancestors were not destroyed by extraterrestrials long ago, that sets asides my fears and leads me to the happy conclusion that technological ETs never have existed in our galaxy. I suspect it will be our own descendants who colonize the galaxy. If there are to be any star wars, they will be among our progeny.

You might enjoy the collection of papers in a book that speaks to both sides of the question: “Extraterrestrials: Where Are They?”

Another good one that's more recent is: “If the Universe Is Teeming with Aliens... Where Is Everybody? Fifty Solutions to Fermi's Paradox and the Problem of Extraterrestrial Life”

Even more recent is: “Rare Earth: Why Complex Life is Uncommon in the Universe”

Centaur
2013-May-06, 04:21 AM
A whole lot of "if's" I know with the only real certainty being that it is a pretty pointless Universe, if we were to be really alone.

Why must there be a point?

molesworth
2013-May-06, 12:13 PM
I suspect that technologies like air traffic control radars are much more important to the detectability of a civilization than are radio communications; these are likely to continue for the foreseeable future. They aren't easy to detect, as they are highly directional, and pulsed, as opposed to somewhat omni-directional (broadcast TV and radio are not omni-directional; both use antenna systems which concentrate their output to minimize energy going vertically upward. Not much audience up there) and continuous.
Hmm, I hadn't really thought about ATC (and other) radar emissions. Even though they're much more directional, or swept, the pulsed operation may make them easier to detect as being artificially generated. I'll have to have a closer look at these, thanks.


As for detectable broadcasts, they're probably only about 70 years old, not existing before the exploitation of radio frequencies that weren't reflected by the ionosphere, so this puts one hard limit on the size of the detectable radio sphere. I have read that the Earth emits more radio frequency radiation than the Sun, so, if that's correct, it may offer a way for a culture with sufficiently advanced radio telescopes a method to detect Earth, and a spectral analysis of the RF radiation may provide indications that it's not entirely natural. That's a lot of maybe, and it's likely to be very difficult, as it would require something akin to an RF version of Kepler staring at suspect stars.
I think SETI searches to date have shown just how hard it is to build the kinds of systems neccessary to detect the very faint signals in the noise. And to be honest, I think it may be a while before we're at the stage where we could detect "earth-like transmissions" from more than a few light years away. A space-based observatory would probably be the best option, but that's unlikely to get funding in the short term.

Hlafordlaes
2013-May-06, 01:08 PM
Now that I think about it, shouldn't this thread be in LiS?


Despite SETI proponents promoting a rather dubious Drake Equation, logic trumps weakly devised probability estimates. Numbers like billions and trillions may dazzle the mind, but they are practically infinitesimal compared with number of possible arrangements of organic molecules for which very few could replicate and become something like DNA. Matter and energy may have had to jump through countless high and tiny hoops to produce mankind. But despite the odds, they obviously succeeded at least once. Although that it no way proves it happened twice or was even likely to have occurred elsewhere. There may be a zillion planets out there, but that does not imply that technological civilizations “must have” evolved on some of them.

Simply to assemble primordial molecules into the simplest DNA or RNA chain capable of reproducing is stupendously unlikely, although it had to happen once. Another planet crashing into early Earth was hugely unlikely, but it was necessary to produce the Moon which stabilizes the Earth’s rotation and produces significant ocean tides. These were necessary for complex life to develop and move to land. It’s highly unusual for a planetary system to include a Jupiter size planet in a low eccentricity orbit and much further from the central star than an earthlike planet, but it’s needed to eat up most rogue comets and asteroids that could destroy life on Earth. Every step leading to the quite recent development of humankind was beyond reasonable expectations. But it happened once despite the odds, and if only once then obviously Earth is the only place in which we could be having this discussion.

And the way it happened, which we a still unraveling, should indicate to us a bit more about probabilities given certain conditions. Two promising findings are the presence of DNA nucleobases in meteorites (http://www.space.com/12569-meteorites-dna-building-blocks-discovery.html), and the presence of a form of phosphorus needed for ATP (http://www.rdmag.com/news/2013/04/power-behind-primordial-soup-discovered) that, when reacting with volcanic acid pools, yields a possible precursor for chemical life ("primordial soup.") Finding those same conditions holding in a variety of other systems, at least to the extent we can detect from spectra etc., should help with further estimates. I just think these are early days to make hard estimates.

From there to technological civilizations is indeed a stretch, as so far it appears evolution is hardly directed, and can as easily result in a stable population of dinosaurs as it does tool-making primates. I think the probability estimates for advanced ET should remain at "fat chance" until such time as something definitive is detected or discovered.


.... I would be concerned about the designs of a race of technological extraterrestrials that became aware of our existence. It may be unfortunate, but those who assume (hope, wish) that evolution will eventually lead to harmony and brotherhood among all intelligent creatures are probably kidding themselves. Evolution has no “ultimate purpose”, no goal. Survival is what matters, and its means may not be what some Pollyanna thinks it should be. Yet I submit that it is often Pollyanna who is searching for extraterrestrial intelligence. Polly is relatively harmless as long as she only attempts to receive signals and not send them.

To some the notion that intelligent extraterrestrials would come to guide us, gives them almost religious comfort even if they have abandoned traditional religions. Yet this is a motivation for many SETI people. But would we really want to become like Eloi and have no need to think or provide for ourselves? Would we prefer to have learned the laws of mechanics from ET rather than Galileo and Newton? If ET really came "to serve man”, would we actually be better off? Would life be worth living?

Granted, ET is more likely to behave like Gordon Gecko than the Geico Gecko. However, I would not assume that another species would not have something to add in terms of approach, perspective, methods or observations. Learning interactively with another species is no different than learning with others of your own, only possibly more entertaining. Hey, what if they burp in Morse code? The adolescent male in us will have an excuse to play! And that's what life is really only good for, anyway.

iquestor
2013-May-06, 01:36 PM
I read "Rare Earth" as well as "How to build a Habitable Planet", "crowded Universe", "Why Aren't They Here", and many other books on the subject of ET Life and Intelligence.

The Odds that Earth's living biosphere is unique in the galaxy, let alone the Universe, seems very unlikely to me, and I don't think we know the whole story of our own planet's history to make conclusions that it takes an astronomical set of circumstances implemented in a correct order with impeccable timing to produce complex life.

It has been argued in the past that planetary formation was probably a fluke around our star because they couldnt get their math models to work and produce planets in simulation. Now we know of hundreds, with thousands more to be vetted after verification of Kepler Data incoming over the next few years.

Granted, the nearest intelligent life may be thousands of LY away, or it may be within 50 LY. In a few decades spectroscopy may well give us positive indications of living biospheres within a few hundred LY, and then maybe we can study further to see if Intelligence is also there.

I am hopeful that we will have confirmation of a living biosphere outside of earth before I pass on.

If you want some hope, watch Dr. Isrealian's TED Talk on spectroscopy (http://www.ted.com/talks/garik_israelian_what_s_inside_a_star.html)

I love this video!

kevin1981
2013-May-06, 02:02 PM
We could be the first intelligent species in the universe, someone has to be !

Hlafordlaes
2013-May-06, 02:34 PM
Make that, first species to regard itself as intelligent.:whistle:

Actually, you are quite right, tho. Could be.

iquestor
2013-May-06, 03:01 PM
Yes, we could be the first. However there is a lot of time before us where life could have arisen. Who knows?

Centaur
2013-May-06, 04:44 PM
It may be that the chain of events required to produce a technological civilization in only 13.8 billion years of a universe’s existence is ridiculously unlikely, almost impossible. Nevertheless, it happened here on Earth. Yet that in no way indicates it “must” have happened elsewhere. As has been said in this forum, someone has to have been the first. I suspect it is us.

Some ETI enthusiasts like to bring up Sagan’s “billions and billions” or even trillions of stars and planets. Carl must have known that was hype for his TV series. Those numbers may be considered the probabilistic equivalents of “a few”. Let’s look at how probability may be related to the current matter.

Say you have a deck of 100 cards with the numbers 1 through 100 on their faces. That’s a far simpler arrangement than the atomic sequence forming the genes of the most primitive virus. You shuffle the deck in a thoroughly random fashion. It’s been estimated that there are 10^80 (a 1 followed by 80 zeroes) atoms in the knowable universe. Now imagine that every atom contains an angel with his own little deck which he randomly shuffles. Utilizing the laws of probability, what is the expected number of decks in which their order would match yours?

A deck of cards can be shuffled in n! different ways, with n being the number of cards in the deck and ! being the factorial sign. 100! = 9.33262 x 10^157 (more than a 9 followed by 157 zeroes). That means roughly 9 x 10^77 (a 9 followed by 77 zeroes) universes, all of whose atoms represent shuffled decks of 100 cards, would be required for the expected number of matches to your deck to be 1.

Numbers of objects totaling billions (? x10^9) or trillions (? x 10^12) may boggle the minds of humans, but they can pale in significance compared with the numbers of possibilities resulting from the consideration of probabilities. While finding a match to your deck under the stated conditions may be considered possible, I hope you agree that it would not be much of a stretch to refer to it as being virtually impossible.

The point is that it was quite a trick for lifeless atoms to have once assembled themselves into a meaningful RNA/DNA-like sequence that could replicate. Nevertheless it was possible, and happened here on Earth long ago. A vast number of extremely unusual circumstances must have combined at least once in an unbroken chain to eventually produce a technological civilization, or else we would not be conducting this conversation. But our being here in no way implies that it also must have also happened elsewhere in the galaxy, especially when considering all of the negative findings so far. Some of the terms in a correct Drake Equation may be virtually infinitesimal.

Swift
2013-May-06, 04:58 PM
As is stated in the stickies for Q&A:

To elaborate, this section of the forum is for astronomy and space exploration questions with straightforward, generally accepted answers.

...

Questions that are likely to lead to extended discussion about the correct answer, or that have no clearcut correct answer, should be posted in the forum most appropriate to the topic of the question.
This question has no clearcut answer and is almost assured to have an extended discussion (as the many past threads on this topic will show). The thread is moved to LiS from Q&A.

cjameshuff
2013-May-06, 09:23 PM
The point is that it was quite a trick for lifeless atoms to have once assembled themselves into a meaningful RNA/DNA-like sequence that could replicate. Nevertheless it was possible, and happened here on Earth long ago. A vast number of extremely unusual circumstances must have combined at least once in an unbroken chain to eventually produce a technological civilization, or else we would not be conducting this conversation. But our being here in no way implies that it also must have also happened elsewhere in the galaxy, especially when considering all of the negative findings so far. Some of the terms in a correct Drake Equation may be virtually infinitesimal.

There's many theorized ways for life to form, and it didn't necessarily need to do so all at once or all in the same place. There's several ways metabolism could have preceded discrete replicators, or for replication to occur in some crude form without RNA or DNA to serve as genetic material. These processes could make the development of RNA and DNA as information-carrying materials and development of life as we know it much more likely. Also, the exact same combinatorial arguments apply to the systems life developed in...there were countless different interactions occurring on early Earth. Words like "trillion" don't come close to describing the number of "experiments" constantly going on, and we know for sure similar compounds can form.

Fossil evidence of life exists more or less as far back as evidence of an Earth that could support life. Either Earth got extremely lucky, or it's not actually all that unlikely.

However, if it took just 1.4 times as long to develop multicellular life...modern Earth wouldn't yet have any. If it took twice as long, life on Earth might go extinct first due to the warming sun. The jump to multicellular life was evidently a major hurdle. I suspect there's life in all sorts of odd corners of the galaxy, very possibly several examples in our solar system, but almost entirely microbial. Perhaps only relatively long-lived stars have any real chance at multicellular life, our sun being toward the short-lived end. And the steps from there to a technological civilization appear far from inevitable. I don't think it's too far-fetched that we're the first in the galaxy. However, it's also not clear how likely this is to be the case...there's just too little information to say.

Hlafordlaes
2013-May-06, 09:44 PM
A deck of cards can be shuffled in n! different ways, with n being the number of cards in the deck and ! being the factorial sign. 100! = 9.33262 x 10^157 (more than a 9 followed by 157 zeroes). That means roughly 9 x 10^77 (a 9 followed by 77 zeroes) universes, all of whose atoms represent shuffled decks of 100 cards, would be required for the expected number of matches to your deck to be 1.

Numbers of objects totaling billions (? x10^9) or trillions (? x 10^12) may boggle the minds of humans, but they can pale in significance compared with the numbers of possibilities resulting from the consideration of probabilities. While finding a match to your deck under the stated conditions may be considered possible, I hope you agree that it would not be much of a stretch to refer to it as being virtually impossible.

The point is that it was quite a trick for lifeless atoms to have once assembled themselves into a meaningful RNA/DNA-like sequence that could replicate. Nevertheless it was possible, and happened here on Earth long ago. A vast number of extremely unusual circumstances must have combined at least once in an unbroken chain to eventually produce a technological civilization, or else we would not be conducting this conversation. But our being here in no way implies that it also must have also happened elsewhere in the galaxy, especially when considering all of the negative findings so far. Some of the terms in a correct Drake Equation may be virtually infinitesimal.

This brings up the issue of discrete combinatorial systems and "valid" combinations. To take an example from human language, with a very restricted set of phonological elements, the varieties of expression (sound sequences) for the same concept within single languages is well known (e.g., auto, car), and if we take it across languages, vast. While chemistry has different combinatorial rules, it seems there must also be more than one way to make self-replicating systems. This reduces the limitations imposed by a single solution alone among all possible derivations.

Not being a chemist, of course, I really am just tossing metaphors around. However, just from tracking stuff in materials science, it seems to me there is a lot left to learn about the total possible set of atomic and molecular constructs. Some of the unknown ones might be amenable to self-replicating systems.

TooMany
2013-May-06, 10:54 PM
It may be that the chain of events required to produce a technological civilization in only 13.8 billion years of a universe’s existence is ridiculously unlikely, almost impossible. Nevertheless, it happened here on Earth. Yet that in no way indicates it “must” have happened elsewhere. As has been said in this forum, someone has to have been the first. I suspect it is us.

Some ETI enthusiasts like to bring up Sagan’s “billions and billions” or even trillions of stars and planets. Carl must have known that was hype for his TV series. Those numbers may be considered the probabilistic equivalents of “a few”. Let’s look at how probability may be related to the current matter.

Say you have a deck of 100 cards with the numbers 1 through 100 on their faces. That’s a far simpler arrangement than the atomic sequence forming the genes of the most primitive virus. You shuffle the deck in a thoroughly random fashion. It’s been estimated that there are 10^80 (a 1 followed by 80 zeroes) atoms in the knowable universe. Now imagine that every atom contains an angel with his own little deck which he randomly shuffles. Utilizing the laws of probability, what is the expected number of decks in which their order would match yours?

A deck of cards can be shuffled in n! different ways, with n being the number of cards in the deck and ! being the factorial sign. 100! = 9.33262 x 10^157 (more than a 9 followed by 157 zeroes). That means roughly 9 x 10^77 (a 9 followed by 77 zeroes) universes, all of whose atoms represent shuffled decks of 100 cards, would be required for the expected number of matches to your deck to be 1.

Numbers of objects totaling billions (? x10^9) or trillions (? x 10^12) may boggle the minds of humans, but they can pale in significance compared with the numbers of possibilities resulting from the consideration of probabilities. While finding a match to your deck under the stated conditions may be considered possible, I hope you agree that it would not be much of a stretch to refer to it as being virtually impossible.

The point is that it was quite a trick for lifeless atoms to have once assembled themselves into a meaningful RNA/DNA-like sequence that could replicate. Nevertheless it was possible, and happened here on Earth long ago. A vast number of extremely unusual circumstances must have combined at least once in an unbroken chain to eventually produce a technological civilization, or else we would not be conducting this conversation. But our being here in no way implies that it also must have also happened elsewhere in the galaxy, especially when considering all of the negative findings so far. Some of the terms in a correct Drake Equation may be virtually infinitesimal.

In combinations of shuffled cards, all combinations have equal probability. Since the possible combinations are extremely numerous, any specific combination is fantastically unlikely. However, chemistry is nothing like that. Instead certain combinations are favored due to the detailed physical behavior of different elements. We have indisputable evidence that under various conditions, more complex organic molecules form spontaneous from much simpler ones and do so rather quickly. Some of these molecules are identical to amino acids that we find in living things.

We don't know precisely what happened to bring about a reproductive molecule or collection of molecules, but we also don't have evidence that it is extremely improbable. There are hints that it is probable:


Life seems to have emerged on Earth at about the time it was cool enough not to destroy organic molecules involved in life.

There are variety of mechanisms used by living things to get the energy they need to grow and reproduce. In other words, there are multiple pathways to sustaining life.

Life is robust. It is found in all places on earth where organic molecules can be formed and persist and liquid water is present.

This is not proof that emergence of life is probable but rather hints. Some biologists and astrobiologist seem to believe that if conditions are within certain boundaries, life will emerge. As yet, we don't know what all these conditions are. Conditions are very different on Earth now than when life first emerged, but cleary life adapted to survive through 3.5 billion years of changes.

P.S I think I'm repeating points that cjameshuff already made above. I wonder if it's possible that multicellular life took a long time to emerge due to severe environmental disturbances such as asteroid impacts, which have since tapered off.

iquestor
2013-May-06, 11:50 PM
To me, the sudden emergence of life as soon as it was able to take hold on early earth doesn't mesh with the idea that "origin of life is extremely unlikley to happen" on other planets.

Large, complex life is certainly another matter, However, it would seem very unlikely to me that Earth is extremely special, even unique, in the Universe. That we are indeed the first intelligence would be way more astounding (to me, at least) than to find out there are a hundred intelligence civs in the milky way.

Selfsim
2013-May-07, 12:49 AM
… Some of these molecules are identical to amino acids that we find in living things. :confused: … Then they are amino acids, no? ...

Hlafordlaes
2013-May-07, 01:11 AM
Selfsim, I was wondering when you'd join us. Don't always follow your points, but I do enjoy their contemplation. [Exits stage left to find a tablet accessing 100 wiki pages...]

TooMany
2013-May-07, 09:59 PM
:confused: … Then they are amino acids, no? ...

Yes.