Hoping Phoenix finds life? Read this 1st!

[Usonian]

I wasn’t going to do this but ............ “Hey, Johnny. If you so smart, WHERE ARE THEY?”

and also,

It's not, by any means, that ............ I leave what else they might do as an exercise for the reader.

The length of your posts must violate some Forum rule or other. They are consequently inadmissible. Thus, I win this debate!

Although childish, I hope you appreciate the lawyerly nature of my rejoinder - when all else fails, fall back on the strict form of the law, or resort to Roberts Rules of Order, or just change the subject. (Tactics used in Congresses, Parliaments and on playgrounds the world over.)

...

Given the brain power of the sources you are quoting, and my own very ordinary powers, the logical move would be to throw in the towel. But I like the sound of my own keyboard clicking...

First, by way of verifying that I understand, let me reduce your point to a three-year-old level I can grasp:

1. Start with the premise that our galaxy is loaded with Earth-like worlds and technical civilizations.
2. A self-replicating von Neumann probe is within the realm of possibility, even for techno-newbies like us (or just a few decades more advanced than us). Thus, in the course of Galactic history there were many, many opportunites for at least one of those civilizations to have created von Neumann probes.
3. Since the spread of the (maybe nanotech?) von Neumann probes is unstoppable, they should by now be pervasive and we should see some evidence of there existance.
4. Since that evidence is lacking, we must call into question the initial premise (ala Fermi) and conclude that our galaxy is NOT loaded with sentient beings and technical civilizations. If evolution naturally drives toward sentients, then there must be some filter that prevents the galaxy from being loaded up. Or, the galaxy isn't loaded up because sentients is a rare evolutionary oddity, maybe even one-of-a-kind.

I should read up on this stuff before trying my hand a replying, but my own clicking draws me on. Just a couple of the objections that leap to mind:

Isn't there something essentially looney in creating a self-replicating machine? Given that the Homo sapien bio-machine is self-replicating at an unsupportable rate, why would we (or any other sentient "out there") create a whole new brand of thoughtless self-replicators? And if we (or they) did such a looney thing, why would we send them off into interstellar space? What's to be gained? I'm not convinced that this brand of lunacy is inevitable.

What constitutes a galaxy "loaded" with sentient life? 1,000 sentient species seems like a lot to me, but compared to 100 billion stars it isn't much. Are 1,000 sentient species enough to make it inevitable that one of them will venture into self-rep tech lunacy? I'm not convinced.

Come to think of it, when Fermi asked, "If you so smart, where are they?" Was he "dissing" the notion of a "loaded" galaxy, or the notion of inevitable von Neumann probes, or both?

Where there is construction and replication, there is error. Wouldn't a von Neumann probe be just another life form - mutating, evolving and eventually expiring into extinction, just like every other living species? Even if one (or a few) instances of von Neumann probes are inevitable in a galaxy "loaded" with sentients, isn't it just as likely that those few von Neumann probe "species" would sink into extinction before they filled the galaxy?

I am guessing that my objections are nothing new to this debate - you probably have ready answers to each. Well, in the words of your fellow Texan, "Bring it on..."

BTW, Greg, your posts may be long, but they're engaging - you tell a great story. I suppose you can employ those talents in a court room, but you may have missed your real calling. Write a book - and tell John Grisham, Esq. to look out.

 

[reekchaa]

I don't think anyone can have a clue what the real future holds for intelligently evolving beings.
The more we search for the constraints on anything, the more our children will strive to bypass those constraints and render them obsolete. Fantastical revelations await new minds and methodologies of learning/thinking/computing, free of the imperceptible cage that comes from popularistic thought.
Simple natural optimism is our best clue.
(so Let's all take a whiff of what the rock is cooking :yu

 

[Andy44]

Isn't there something essentially looney in creating a self-replicating machine? Given that the Homo sapien bio-machine is self-replicating at an unsupportable rate, why would we (or any other sentient "out there") create a whole new brand of thoughtless self-replicators? And if we (or they) did such a looney thing, why would we send them off into interstellar space? What's to be gained? I'm not convinced that this brand of lunacy is inevitable.

I don't think it's lunacy, I think it's a good way to spread out and colonize. Even if you want to colonize something close, like Mars, say, or even the moon, it makes sense to send machines like these to set things up for you before you arrive in numbers.

Later, if interstellar travel proves to be just too much for biologicals, your only shot at near-immortality may be to send pure machines out to spread through the galaxy and become the "new you", which was of course, the premise behind the story of 2001: A Space Odyssey.

In that story, the monoliths were extremely advanced von Neumann devices which contained the individual and collective consciousness of the biological species which had spawned them and which was now presumed to be long biologically extinct.

4. Since that evidence is lacking, we must call into question the initial premise (ala Fermi) and conclude that our galaxy is NOT loaded with sentient beings and technical civilizations. If evolution naturally drives toward sentients, then there must be some filter that prevents the galaxy from being loaded up. Or, the galaxy isn't loaded up because sentients is a rare evolutionary oddity, maybe even one-of-a-kind.

Yeah, I'm guessing the answer is the first sentence: galaxy NOT loaded with sentients. That famous Drake equation has always been far too optimistic for me; there are too many numbers just made up in there. The idea that there are lots of Earth-like planets just doesn't square with what we've observed so far. Every spheroidal celestial body in our solar system has proven to be fantastically unique and no two are the same. We have four gas giants and they are all significantly different; we have 3 terrestrial planets aside from our own and none of them turned out like this one. Every moon is different, every one of them! I have no reason to believe that any of the planets we see around other stars will look anything like Earth, complete with a circular, habitible-zoned orbit, and a nice moon to keep it from wobbling too much and cycling the climate so that life has no time to evolve, and with all the correct ingredients.

I'd like to believe otherwise, but show me the evidence!

---------
ETA: As an aside, it just struck me that the Cylons in Battlestar Galactica are an example of man-made von Neumann devices...which puts the show in a new light for me...

 

[GregBurch]

The length of your posts must violate some Forum rule or other. They are consequently inadmissible. Thus, I win this debate!

As I’m sure you’re aware, many courts (all courts of appeal, as for as I know) have limits on the length of briefs. Believe it or not, I’m somewhat infamous for filing very brief briefs. It freaks out the other side when I file a one or two paragraph motion.

Given the brain power of the sources you are quoting, and my own very ordinary powers, the logical move would be to throw in the towel. But I like the sound of my own keyboard clicking...

It is something to think about: The folks who have been troubled by this problem may well count as some of the smartest people in the world. I just tag my angst along with theirs – it makes feel smart just worrying about the same things they worry about.

First, by way of verifying that I understand, let me reduce your point to a three-year-old level I can grasp:

1. Start with the premise that our galaxy is loaded with Earth-like worlds and technical civilizations.
2. A self-replicating von Neumann probe is within the realm of possibility, even for techno-newbies like us (or just a few decades more advanced than us). Thus, in the course of Galactic history there were many, many opportunites for at least one of those civilizations to have created von Neumann probes.
3. Since the spread of the (maybe nanotech?) von Neumann probes is unstoppable, they should by now be pervasive and we should see some evidence of there existance.
4. Since that evidence is lacking, we must call into question the initial premise (ala Fermi) and conclude that our galaxy is NOT loaded with sentient beings and technical civilizations. If evolution naturally drives toward sentients, then there must be some filter that prevents the galaxy from being loaded up. Or, the galaxy isn't loaded up because sentients is a rare evolutionary oddity, maybe even one-of-a-kind.

By Newton, I think you’ve got it.

I should read up on this stuff before trying my hand a replying, but my own clicking draws me on. Just a couple of the objections that leap to mind:

Isn't there something essentially looney in creating a self-replicating machine? Given that the Homo sapien bio-machine is self-replicating at an unsupportable rate, why would we (or any other sentient "out there") create a whole new brand of thoughtless self-replicators? And if we (or they) did such a looney thing, why would we send them off into interstellar space? What's to be gained? I'm not convinced that this brand of lunacy is inevitable.

Well, first, and as an aside, I question the common belief that “the Homo sapien bio-machine is self-replicating at an unsupportable rate.” It’s certainly true with the way we currently go about things that we’re pooping in our crib quite a bit. But it’s not hard at all to imagine ways of doing things that could support far more bio-humans on Earth than we currently do, in high style, and without doing much damage at all to old Mama Earth.

But more to the point, the power of replication is, I’m afraid, irresistible. The things we can already do with it (agriculture, for instance), are good things. Working at a more subtle level will provide technological riches beyond the wildest dreams of Croesus before too long. There are those (Bill Joy, most famously, but others are lining up as they wake up to the possibilities) that would stop the development of self-replicating molecular machines. But the proposals to do so are just as chilling – if not more so – than any “grey goo” fear one might conjure. Basically, you have to lobotomize the human race to excise this knowledge, and then keep it lobotomized – forever. And believe me, there are plenty of not-so-nice people who look forward to harnessing the destructive power of such technologies. So, I’m afraid the only way forward is … forward.

What constitutes a galaxy "loaded" with sentient life? 1,000 sentient species seems like a lot to me, but compared to 100 billion stars it isn't much. Are 1,000 sentient species enough to make it inevitable that one of them will venture into self-rep tech lunacy? I'm not convinced.

Physics is physics, and large numbers are large numbers. The evolved human meat-brain isn’t too good at dealing with either. But consider this: The potentiality of self-replicating automatons (as Johnny von N called them) is inherent in the nature of chemistry and life. It seems inevitable to me that any sentient species that gets to the point of having a scientific world-view will eventually realize the power of this set of ideas. It will take enormous self-control not to use it.

And it may well be in the very nature of evolved life itself that it finds such a step irresistible: To get to the point that it can know about this possibility, it has to have been a successful competitor in its own evolutionary environment. In other words, species that can turn away from the power of self-replication probably don’t evolve to the point of even knowing about it.

As for the large numbers, I’m thinking of TIME. Over the long stretch of a billion years or so that we’re looking at as the period in which life would have evolved to the point of launching a probe-wave, it seems to me inevitable that at least one would.

Come to think of it, when Fermi asked, "If you so smart, where are they?" Was he "dissing" the notion of a "loaded" galaxy, or the notion of inevitable von Neumann probes, or both?

I don’t know. It’s a paradox.

Where there is construction and replication, there is error. Wouldn't a von Neumann probe be just another life form - mutating, evolving and eventually expiring into extinction, just like every other living species? Even if one (or a few) instances of von Neumann probes are inevitable in a galaxy "loaded" with sentients, isn't it just as likely that those few von Neumann probe "species" would sink into extinction before they filled the galaxy?

Well, this begs the question of whether an evolutionary process that works itself out over the space of a galaxy and time spans of millions of years will necessarily “sink into extinction” over such a period. I don’t think there’s any good reason to think so.

On the other hand, your point about replication error is a good one. Time to talk to Mr. Darwin. Again, I leave the implications of that to the reader.

I am guessing that my objections are nothing new to this debate - you probably have ready answers to each. Well, in the words of your fellow Texan, "Bring it on..."

No – they’re not new, but it’s good to see someone come to this fresh and develop the same questions that very, very smart people have been asking about Fermi’s little quip for over 60 years.

BTW, Greg, your posts may be long, but they're engaging - you tell a great story. I suppose you can employ those talents in a court room, but you may have missed your real calling. Write a book - and tell John Grisham, Esq. to look out.

I do love to explain things in the courtroom. But as for the book, well, events keep overtaking my writing. And there’s the small distraction of making a living in the meantime and creating the odd Orbiter addon along the way.

GB

 

[MattNW]

I wasn’t going to do this but since someone as smart as Scott “doesn’t get it,” I’m going to go ahead and crap on everyone’s parade.

As a historian, I like to think of Fermi’s paradox in the context in which it was actually developed. It all happened during what may be the greatest single concentration of human brilliance that has ever been managed, the Manhattan Project. Out there in the high desert, the best minds of a generation of geniuses were brought together to solve some really hard problems. One of them was John von Neumann. Over the space of a few months he did what I call “figure everything out.” He went from the basic insights of Turing to what we still to this day call “von Neumann Architecture,” the basic layout of the computer you are using to read these words. Immediately upon designing the modern computer, von Neumann realized that Turing’s insights led inevitably to the conclusion that the development of machine intelligence was a probability and that informatics could be applied to matter in the form of “self-replicating automata,” i.e. robots that build copies of themselves.

Armed with all this great insight, Johnny (as he was called) sprang his vision for real, working computers and self-replicating robots, built in the form of space probes, on the gathered geniuses at one of Robert Oppenheimer’s famous nighttime, beer-fueled rap sessions out at Los Alamos. Everyone was suitably impressed: Given just realistic sub-light velocities, the exploration of the entire galaxy within the space of a short few million years at most would be possible – with technologies barely beyond the reach of those who were in the process of building the first nuclear weapons.

As the story goes, later that night, Johnny von Neumann was out on the porch of Oppenheimer’s house, enjoying his last beer and looking up at the millions of stars in the crystal-clear desert sky. He was savoring the grand vista of the expansion of intelligence out into the universe. But then little Enrico Fermi wandered out. He looked at von Neumann and said quietly, in his heavy Italian accent: “Hey Johnny, if you so smart, WHERE ARE THEY?”

The last stragglers from the party were just leaving at that moment, and heard Fermi’s question. Given the project they were all working on, it didn’t take but a moment for all present to realize the import of Fermi’s question.

Ever since that night, Fermi’s little question has been festering beneath the surface of the great age of technological advance in which we live. But his simple question – “where are they?” – took on new import in the 1980s. During that decade, a young MIT grad student named Eric Drexler began to fill in the broad swaths of von Neumann’s presumptions about technology. This resulted in Drexler’s PhD dissertation at MIT, which was in turn reworked into a book called “The Engines of Creation.” In that book, Drexler laid out the foundations of what is today known as the science and technology of nanotechnology.

Over the next few years, Drexler’s work attracted a number of people into a group who began to consider how his work might be translated into real, working technology and how the incredible power of molecular-scale manufacturing might affect society. Among that group were Robin Hanson, the originator of the idea of “the Great Filter,” people like Ray Kurzweil and Marvin Minsky, and later Nick Bostrom, the author of the article which started this thread. One minor figure in that group was an obscure lawyer from Texas, who played a small part in developing the first set of guidelines for the safe and ethical development of nanotechnology, yours truly.

The connection to Fermi’s Paradox is this: Based on Eric Drexler’s work, it was possible starting in the mid-1980s to see a very real pathway of scientific, technical and engineering development that could realistically lead to the building of real “von Neumann Probes.” During the 1990s, people in Drexler’s orbit began to sketch in the details of that pathway, so that it began to be reasonable to make at least somewhat realistic projections of how long it might take to reach the level at which someone could build a real von Neumann probe. During those heady days, there were projections of as little as ten years. But even the most conservative saw the achievement of that goal within, at most, a hundred years or so.

Yes, there were skeptics. Foremost among them was Richard Smalley of Rice University, the man credited with the development of the C60 family of carbon materials, i.e. buckmisterfullerenes, “bucky-tubes,” etc. Smalley’s objections to Drexler’s work resulted in a famous face-off in the pages of Scientific American, in which Smalley and Drexler argued for some time about the actual feasibility of the kind of general-purpose, programmable, molecular-scale manufacturing machines Drexler had described in “Engines of Creation” and later works. Smalley died without ever admitting defeat, but I believe the consensus today is that he was wrong and Drexler was right: “machine phase” molecular “mechanosynthesis” is possible, and progress toward achieving it continues at a rapid pace.

So … with that little bit of historical perspective, we return to the basic question. If we can do it, so can “they”. If we aren’t unique, then some other species of intelligent life, somewhere else in the galaxy should have – LONG AGO – done what we are on the threshold of doing. And if they did – if just one among however many species there might be – began the process of seeding the galaxy with intelligence, then the process would produce unmistakable signs. Just as you can’t fly over any part of the world in which people have lived for a long time without seeing their imprint on nature, so we should see clear evidence of the seeding of the galaxy with intelligent artifacts.

In his early work, Robin Hanson explored these questions, and demonstrated with some pretty compelling reasoning and mathematical modeling that it only takes one tiny spark to start this process, and that evolutionary processes would favor those efforts at seeding the galaxy that would produce the most detectible results. His paper “Burning the Cosmic Commons” has become a classic on this subject and is, by now, at least a decade old. It basically works out the mathematics of the Fermi Paradox in chilling detail.

“Hey, Johnny. If you so smart, WHERE ARE THEY?”

Interesting but has anyone considered that a civilization may have risen, searched for extra-non-terrestrial life and given up. Look at the problems SETI has encountered with funding. How many here are running the little program in the background to help that search? We've only been searching for extraterrestrial life for 40 years or so and already people are ready to call it quits.

Consider the vastness of space. If a civilization arose on a time scale similar to our own and if that civilization started searching around the same time as we and instead of listening like we do they actively broadcast powerful radio signals the best we can hope for is that they lie within 40 or so lightyears of us. If they live farther away we wouldn't be able to receive their signals yet. Even with the best of circumstances a civilization within 40 lightyears of us is hugely improbable. Note I'm saying a civilization not life. The factors that can lead to a self aware technological civilization with the intent, resources and wherewithal to try to contact us must be rare but even if they are rare with all those stars and all the time they may have had to develop there is a good possibility they still do exist or have existed and we just haven't noticed yet.

Also consider the rise and fall of civilizations. Many civilizations have risen here on Earth and decayed into barbarism. Maybe it takes several ups and downs for people to get their acts together. Maybe we are on course for a downfall.

While we are speaking of sci-fi stories I remember one where a race contacted us and we busted our tails to build a ship capable of going to them for a face to face. As the ship traveled at relativistic speeds and closed in on the planet they kept intercepting new and newer messages. The final message only ten years or so out from the planet was a, "Do not land here" message. When they finally reached orbit around the planet all they found was a lot of radiation and destroyed cities.

I won't even go in to the possibilities of life unlike our own. Life who may be intelligent but an intelligence so unlike ours that we have no way for the two lifeforms to interact. It boggles the mind.

 

[movieman]

Regarding point 1: I think that 50 years of searching through a 100-billion-star galaxy barely passes for a beginning.

If there was a species out there a million years ahead of us, we wouldn't need SETI to find them; their existence would be as obvious to us as our existence would be to a cave-man living in Central Park. We might not understand what they were doing, but we wouldn't be able to miss them.

And a million years is a tiny fraction of the lifespan of the universe; if intelligent life is common, then a million year old civilisation would be considered young. Just look at how far we've come in the last thousand years, and imagine progressing for another thousand times that long; do you really think that kind of technology could be hidden from us?

In reality, though, everywhere we look the galaxy appears to be a wasteland; there's nothing that even remotely requires an artificial explanation, though I'd agree that some of the oddities we see in other galaxies might be huge engineering projects by creatures far more advanced than us.

Someone has to be the first technological society in the galaxy, and, as I said, if we start colonising it then there's probably not going be time for a second.

 

[GregBurch]

In reality, though, everywhere we look the galaxy appears to be a wasteland; there's nothing that even remotely requires an artificial explanation, though I'd agree that some of the oddities we see in other galaxies might be huge engineering projects by creatures far more advanced than us.

Relating to this very good point, one idea that seemed to hold promise was suggested during the glory days of the late 1990s. The idea proposed by this fellow (who is, as it happens, Ray Bradbury's nephew) was that the answer can be found in the "missing mass" problem. His theories about this were quite well developed, and he even offered some observational tests that could be done to make a first-order determination of whether the artifacts of intelligence in the universe were there among the missing mass.

Unfortunately, those tests haven't borne out his theories, and it now seems probable that there are completely "natural" explanations for much, if not all of the missing mass.

Oh well ...

GB

 

[MattNW]

If there was a species out there a million years ahead of us, we wouldn't need SETI to find them; their existence would be as obvious to us as our existence would be to a cave-man living in Central Park. We might not understand what they were doing, but we wouldn't be able to miss them.

How obvious are we to the microbes on a slide? Do the ants in a grade school science project have an awareness of the school and classroom?

Look at our track record so far. Wars, famines, African slaves, Native Americans, Australian Aborigines, nuclear weapons, M.A.D. and I could go on and on.

People ask the question, "Why haven't they come to see us?" but I ask, "Why would they?" We are just a bunch of badly behaved children.

 

[Usonian]

Having done the minutes and minutes of researching "the internets" I come up with this:

http://www.rfreitas.com/Astro/FermiHowler1984.htm

Just one of thousands of Fermi Paradox "con" sites. The bottom line is that currently there is no bottom line! There is so little actually known that one can argue any side of the Paradox all day long. And besides, isn't irreducible doubt the essence of a paradox?

One thing I picked up from my minutes of research of the "con" side is that, however stated, the Paradox appears to always contain a statement of "should" or "ought" (see Step 3 in my own formulation above). Those words reek of opinion, value judgement, prejudice and assumption. They are no better than "maybe" or "I reckon." The argument is that you can not arrive at a firm declaration - Sentient Alian Cultures Do Not Exist - when the train of thought runs through assumptions like "they ought to have overrun the galaxy" and "we should be able to detect them." Those aren't facts.

MattNW's makes the point. Is the bacteria aware of us? Maybe, but problably not. Would we be "bacteria" to interstellar travelers? Maybe. Should we be able to detect them? Not necessarily. Is it hubris and arrogance that dismisses the notion that we could be like bacteria to "them?"

If a bunch of Manhattan Project geniuses - shootin' the sh-t and knockin' back some beers - aren't arrogant... well, who is?

But what fun to discuss:lol:

 

[Scarecrow]

About the "Where are they?" question, I think there is one possibility that we've all overlooked:

We are von Neumann style self-replicating automata. Think about it: In the lab, scientists have simulated conditions on primordial earth, and been able to synthesize all the essential molecules of life, with one exception: nucleic acids. Suppose that all these organic molecules were floating around on Earth, but without nucleic acids. Suddenly, an alien reentry vehicle enters the atmosphere and seeds it with nucleic acids in some arrangement likely to result in bacteria of some description, which would then be likely to evolve into multicellular, and eventually intelligent life, which turns out to be us. We are now considering sending out von Neumann style self-replicating automata. A simple way to do this would be to come up with some genetic arrangement(s) of synthesized nucleic acids (or equivalents likely to react appropriately with other potential life forming chemical mixes found on other planets), and then freeze dry the whole collection, load this material on a bunch of relatively simple spacecraft, and send them out to colonize other worlds. Assuming that this is the correct explanation for the origin of nucleic acids on Earth, we are the answer to the "Where are they?" question.

However, I personally believe that there is some Earthly explanation for the origin of nucleic acids that we simply haven't thought of yet.

 

[tomek]

Tangential to this conversation: http://projectrho.com/rocket/rocket3aa.html#killingstar

 

[Andy44]

Tangential to this conversation: http://projectrho.com/rocket/rocket3aa.html#killingstar

I have read that before back when I first found that site, and it is a fascinating, anf frightening discussion. But I don't think it's a good reason to lose any sleep. It's based on as many assumptions as all the other stuff we've talked about in this thread.

Does make you think, though.

 

[Tschachim]

It's not, by any means, that "every form of life must build fancy replicating space probes" -- but rather that any do. The problem is this: Once started, the process carries on by itself, and grows at a geometric rate. As Hanson demonstrated, all one needs to know is 1) what the doubling time for a von Neumann probe is, 2) what the average distance between the stars in the galaxy is and 3) what the transit speed is to calculate how quickly every star system in the galaxy gets at least visited. As it turns out, even very conservative values for 1 and 3 yield very, very short time frames for such a result, something Fermi figured out in a few minutes in a less rigorous way.

OK, thanks for clarification, but - mainly agreeing with Usonian - I still think it's wrong. You use a lot of premises to build the "von Neumann" theory, this theory predicts von Neumann probes all around, we don't observe that, so the theory is wrong, which means that one or more of the original premises are wrong. That's fine so far, but now you pick out a certain premise ("there are aliens") and claim that this is the wrong one (and all others are correct), and this is logically not correct. The only fact you have are the missing probes, everything else is assumed, especially all the arguments for ruling out that the other premises could be wrong, and from that fact only you just can't conclude that there are no aliens, it's not paradox, it's wrong.

More specifically I wonder if the assumtion of exponential growth of a von Neumann population is correct. I don't know which models you and the other guys ran, but - as explained in the link Usonian posted - a lot of systems like bacteria etc. have this basic growth schema and we do observe that under certain conditions, but because of a vast amount of reasons they don't do that very often. ... and no, you can't conclude from the fact that we're not wading in a thick layer of bacteria that bacteria don't exist.

But it's an interesting idea worth to discuss and think about, of course, for my part I like Scarecrow's "We are they!" idea most.

Cheers
Tschachim

 

[GregBurch]

I just wrote a lengthy post here, but mistyped my login and discovered to my chagrin that the forum software doesn't save the text past a single login attempt. Perhaps I'll come back to this tomorrow .... damn!

-- aha -- it's saved in my local browser cache -- see below.

 

[GregBurch]

First, thanks to Andy for starting this thread. As I said early on, this "issue space" is one that I spend waaaay too much time thinking about, and have for decades. I haven't written much about it in a long time because, frankly, I haven't encountered a genuinely new idea on the subject in a long time. But it's nice to open the doors and windows and let some fresh air into the dark once in a while.

With all due respect to the "Fermi skeptics" here, I honestly think you're not giving the basic idea time to really germinate in your head. The web page at the "Atomic Rockets" site linked above really does a superb job of working through all the issues. The most important points there are the ones focusing on game theory -- interestingly, an area in which John von Neumann's work was seminal. To my way of thinking, either the relatively straightforward mathematics underlying those ideas is right, or its not. If it's right, then there's a real problem. Again without meaning to give offense, it seems to me that ignoring the power of the simple but clear insights from the game theoretic analysis of the question amounts to little more than "whistling past the graveyard."

To flesh that out a little more, I think you have to do more than say "We don't know enough to even really think about this problem: There are too many assumptions about how alien species might behave." I think you have to point out the actual flaws in the reasoning and develop plausible alternative theories. To be blunt, I don't see them.

Initially, the objection about how replicators don't achieve unbounded geometric growth "in nature" seems plausible. As is said above, the fact that the Earth isn't covered in an ocean of bacterial slime doesn't disprove the existence of bacteria. But consider this: In a very real sense, the Earth IS covered in an ocean of bacterial slime. It only took the development of the microscope to begin the process of determining that bio-replicators exist at basically all possible scales and in essentially all possible places on Earth. This was what I meant when I made the cryptic comment above, "Time to talk to Mr. Darwin."

The point is that there very likely WOULD be evolution of von Neumann probes over astronomically relevant time scales. But that would only result in what we know resulted from biological evolution on Earth: A rich and diverse biosphere teeming with life. At this point in the chain of reasoning, the question presents itself of whether we possess the analog of "the microscope" to detect the ecologies these entities ought to have created by now. It seems to me that we have.

At any rate, the flickering little sparks of optimism I still manage to keep kindled in my brain actually cling to one scenario in which extraterrestrial intelligence may exist (if not commonly), but be undetectable with our current instrumentalities. This is that the passage through the technological phase in which intelligence would spawn von Neumann probes is very swift, and that what lies beyond on the natural trajectory of life is still undetectable to us. This would mean that macro-engineering on the scale we could detect is something that is universally uninviting to ALL intelligence in the universe. This is a big conclusion to swallow, but I can at least barely imagine it. Again, to be cryptic, the answer may lie with the dark matter, but the testable criteria for this scenario become narrower with every passing year.

GB

 

[Tschachim]

Initially, the objection about how replicators don't achieve unbounded geometric growth "in nature" seems plausible. As is said above, the fact that the Earth isn't covered in an ocean of bacterial slime doesn't disprove the existence of bacteria. But consider this: In a very real sense, the Earth IS covered in an ocean of bacterial slime. It only took the development of the microscope to begin the process of determining that bio-replicators exist at basically all possible scales and in essentially all possible places on Earth. This was what I meant when I made the cryptic comment above, "Time to talk to Mr. Darwin."

Yes, there are bacteria all over the place, but they DO NOT achieve unbounded geometric growth (and I don't see why von Neumann probes should, in contrary to all the other really existing, naturally growing systems).

Also, the "microscope argument" is interesting: Despite the fact that bacteria exist in essentially all possible places on Earth, they are not obvious to us, it took a long time until we discovered them. So since we're able to miss something that obvious and all-present like bacteria for a million of years or so, it seems to be quite possible that we're missing the aliens, too.

Cheers
Tschachim

EDIT: But perhaps things are getting clearer for at least for me if you elaborte a little bit on the game theoretic analysis you did...

 

[GregBurch]

Yes, there are bacteria all over the place, but they DO NOT achieve unbounded geometric growth (and I don't see why von Neumann probes should, in contrary to all the other really existing, naturally growing systems).

Also, the "microscope argument" is interesting: Despite the fact that bacteria exist in essentially all possible places on Earth, they are not obvious to us, it took a long time until we discovered them. So since we're able to miss something that obvious and all-present like bacteria for a million of years or so, it seems to be quite possible that we're missing the aliens, too.

Cheers
Tschachim

EDIT: But perhaps things are getting clearer for at least for me if you elaborte a little bit on the game theoretic analysis you did...

1. "The Microscope." Yes, it took a long time to develop the microscope, but the question is whether we can see NOW with the tools we have NOW down/out to the level that would reveal "cosmic replicators." One can waive one's hands and say that "they" are using some kind of technology that tales advantage of physics that we can't even imagine, but that's really no different from a kind of "god of the gaps" spirituality. If, like me, you think we're well along with the program of understanding the basic physics of the universe, then you can't resort to this kind of "magic physics" argument.

2. Game Theory. Basically, we're talking relatively simple Prisoner's Dilemma analysis here. The discussion at the Atomic Rockets site:

http://projectrho.com/rocket/rocket3aa.html#prisonersdilemma

explains this in terms of the most radically negative implications. One need only substitute the option of unleashing a probe wave for the "destroy" option to see how this works.

You can easily combine the "destroy" and "probe wave" scenarios to arrive at a scenario of "unleash probe wave that transforms the galaxy into something we like" -- or even more benignly, "unleash a probe wave that just reports what's out there without giving away our location."

BTW, it might be interesting to take a look at this:

http://computerworld.co.nz/news.nsf/tech/2F5C3C5D68A380EDCC257423006E71CD

 

[Tschachim]

If, like me, you think we're well along with the program of understanding the basic physics of the universe, then you can't resort to this kind of "magic physics" argument.

Well, I think there's a lot "out there" we don't understand yet and we're having no change to figure out how much we know already and what's still missing, but that's only my opinion, of course.

2. Game Theory. ...

Thanks for the links; I may be dumb, but I don't see how this models the dynamics of a von Neumann population in the universe?

Cheers
Tschachim

 

[GregBurch]

Thanks for the links; I may be dumb, but I don't see how this models the dynamics of a von Neumann population in the universe?

It doesn't, actually -- I mistook your question as relating back to the earlier discussion of whether a probe-wave gets started in the first place. There's no better discussion of how a probe wave might work than Hanson's:

http://hanson.gmu.edu/filluniv.pdf

GB

 

[Andy44]

First, thanks to Andy for starting this thread. As I said early on, this "issue space" is one that I spend waaaay too much time thinking about, and have for decades. I haven't written much about it in a long time because, frankly, I haven't encountered a genuinely new idea on the subject in a long time. But it's nice to open the doors and windows and let some fresh air into the dark once in a while.

You're very welcome!

But I now also feel like I'm in over my head arguing with super-brains that have hashed this out for decades prior to my being hatched.

I guess what I'm trying to figure out amounts to this:

We have this thing called "Fermi's Paradox", but we only call it a paradox until we come up with a way to explain it logically, and unless you are superstitious, you know that there is an explanation, even if it's beyond our grasp for the time being, and it's in our best interest to come up with theories to fit the observables.

1. Theory First. Lonlieness: The easiest explanation; that we are the Only Ones, or at least One of the Few, the Proud. That neatly answers the question, "where are they"; they don't exist, or there have been very few and none of them made it as far as we can see. It also fits the observables we have. It's weakness is that there are many who argue that the odds don't favor it, given the number of stars and the large amount of time that has passed since the creation (Big Bang if you like).

2. Theory Second. Pessemism: we are not the Only Ones or the Few, we are just one of many, and so far, the rest have all met with some catastrophe before succeeding in making their mark on the galaxy, the "Great Filter". This suggests that either natural disasters are statistically too frequent to allow civilizations to flourish, or that there is something inherently self-destructive in all sentient space-faring species. Gamma-ray bursts, meteor impacts, and nuclear wars, etc. I think this has a weakness, too, that being that surely among all these myriad civilizations someone must be able to survive these disasters.

3. Theory Third. Paranoia: we are not alone at all, that would be too good. Indeed, we are under the threat of alien civilizations who themselves fear other aliens so much that they actually attenuate their observable footprint, such as curtailing radio signals, and that upon detecting our presence will immediately move to destroy us, possibly using relativistic rockets. Under Fermi's Paradox, this theory must hold that all civilizations are this paranoid, including, ultimately, our own. He who launches his relativistic rocket first wins, damn the ethics, and meanwhile turn off the radios and shut down the von Neumann device projects in order to protect ourselves. This is the game theory discussed on the Atomic Rocket website, and while it's based on cold survivalist logic, we Americans already violated it after WWII when we had the chance to nuke the Soviet Union for a brief window and chose instead to, for once, try not to murder entire populations. Surely other sentient species would develop ethics along similar lines as they evolve, but I may be wrong. I also have a hard time believing that they would go to the trouble of building such an interstellar weapon and at the same time not explore space and use powerful radios.

I'm sure I've missed a few, so feel free to add in what's missing. Once we have a list of possible explanations for Fermi's Paradox, we can estimate which one is most likely and what the best solution might be for our own survival.

I still feel too dumb to argue with such minds, but I can't help it, this stuff is fun to talk about.