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I've made my first novel, Ventus, available as a free download, as well as excerpts from two of the Virga books.  I am looking forward to putting up a number of short stories in the near future.

Complete novel:  Ventus


To celebrate the August, 2007 publication of Queen of Candesce, I decided to re-release my first novel as an eBook. You can download it from this page. Ventus was first published by Tor Books in 2000, and and you can still buy it; to everyone who would just like to sample my work, I hope you enjoy this version.

I've released this book under a Creative Commons license, which means you can read it and distribute it freely, but not make derivative works or sell it.

Book Excerpts:  Sun of Suns and Pirate Sun

I've made large tracts of these two Virga books available.  If you want to find out what the Virga universe is all about, you can check it out here:

Major Foresight Project:  Crisis in Zefra

In spring 2005, the Directorate of Land Strategic Concepts of National Defense Canada (that is to say, the army) hired me to write a dramatized future military scenario.  The book-length work, Crisis in Zefra, was set in a mythical African city-state, about 20 years in the future, and concerned a group of Canadian peacekeepers who are trying to ready the city for its first democratic vote while fighting an insurgency.  The project ran to 27,000 words and was published by the army as a bound paperback book.

If you'd like to read Crisis in Zefra, you can download it in PDF form.

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The Deepening Paradox

A new paper on the Fermi paradox only adds to the mystery: are we alone?

Okay, Keith B. Wiley's new paper does have a somewhat daunting title: The Fermi Paradox, Self-Replicating Probes, and the Interstellar Transportation Bandwidth. But it's a pretty easy read and hugely well worth it--because in this paper Wiley provides what may be the clearest discussion yet of the core puzzle Fermi first proposed sixty-two years ago: if alien technological civilization is even possible, then they should be here; at the very least, such civilizations should be visible to us. That we are instead faced with 'the great silence' is one of the most troubling and, yes, paradoxical, results of modern science.

I addressed the Paradox in my novel Permanence, coming up with a possible new solution for it; although Milan Cirkovic and other astrophysicists haven't disproved my central contention, they've since shown that it's not a show-stopper. As Wiley points out in this paper, even if the lifetime of an interstellar civilization is short; even if they're all doomed; there is no credible argument as to why they couldn't create self-reproducing probes (SRPs) to investigate the entire galaxy that, collectively, outlive the originating civilization. This is the very scenario I paint in Permanence. SRPs are a cheaper solution than one-off expeditions. In fact, SRPs are so efficient a solution to exploration and colonization that, plugging in some highly conservative numbers of how many civilizations there might be out there, Wiley shows that hundreds to billions of such probes should actually be here, in our solar system, right now!

Wiley blows up some of the keystone explanations for the Paradox, including Geoff Landis's percolation model, which previously I'd considered a pretty solid argument. Wiley is so good at demolishing easy explanations, in fact, that he brings us almost all the way back to square one, where Fermi had us in 1950. Where are they? We haven't a clue.

The mystery deepens almost by the day, because we've now identified 700 extrasolar planets and the count is increasing rapidly. We should shortly be racking up lists of Earthlike worlds, and we're closing in on good estimates of how many there must be in our galaxy. And the number is in the billions. So one central argument against the existence of alien life--the 'rare Earth' argument that environments to host it must be rare--has been more or less disproven. And that, just this year.

As possible explanations dwindle, we are being drawn inexorably toward the one explanation that is no explanation: that we really are alone. Why should this be? As Wiley shows, all it would take would be one alien species with our capabilities appearing, sometime in the past couple of billion years, and for that species to surpass where we are now technologically by, oh, say, a couple of hundred years... and the evidence for their existence should be present right here in our own solar system. It's an astonishing conclusion.

So are we alone? Well, there is one other possibility, at this point. I've lately been trumpeting my revision of Clarke's Law (which originally said 'any sufficiently advanced technology is indistinguishable from magic'). My revision says that any sufficiently advanced technology is indistinguishable from Nature. (Astute readers will recognize this as a refinement and further advancement of my argument in Permanence.) Basically, either advanced alien civilizations don't exist, or we can't see them because they are indistinguishable from natural systems. I vote for the latter.

This vote has consequences. If the Fermi Paradox is a profound question, then this answer is equally profound. It amounts to saying that the universe provides us with a picture of the ultimate end-point of technological development. In the Great Silence, we see the future of technology, and it lies in achieving greater and greater efficiencies, until our machines approach the thermodynamic equilibria of their environment, and our economics is replaced by an ecology where nothing is wasted. After all, SETI is essentially a search for technological waste products: waste heat, waste light, waste electromagnetic signals. We merely have to posit that successful civilizations don't produce such waste, and the failure of SETI is explained. 

And as to why we haven't found any alien artifacts in our solar system, well, maybe we don't know what to look for.  Wiley cites Freitas as having come up with this basic idea; I'm prepared to take it much further, however.

Elsewhere I've talked about this particular long-term scenario for the future, an idea I call The Rewilding. Now normally one can't look into the future; in the case of the long-term evolution of technological civilization, however, that is precisely what astronomy allows us to do. And here's the thing: the Rewilding model predicts a universe that looks like ours--one that appears empty.  The datum that we tend to refer to as 'the Great Silence' also provides the falsification of certain other models of technological development. For instance, products of traditionally 'advanced' technological civilizations, such as Dyson spheres, should be visible to us from Earth. No comprehensive search has been done, to my knowledge, but no candidate objects have been stumbled upon in the course of normal astronomy. The Matrioshka brains, the vast computronium complexes that harvest all the resources of a stellar system... we're just not seeing them. The evidence for that model of the future is lacking. If we learn how life came to exist on Earth, and if it turns out to be a common or likely development, then the evidence for a future in which artificial and natural systems are indistinguishable is provided by the Great Silence itself.

Check out Wiley's paper. And just think: the Great Silence may turn out to be no paradox at all, but positive data about what our own future will look like.

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I hasten to add...

Posted by Karl Schroeder at Nov 30, 2011 04:31 PM
...That SRPs aren't the only way to explore. A judicious use of gigantic telescopes at gravitational lensing locations would be cheaper, permitting the study of city-sized objects from a distance of light-years.

This doesn't falsify my basic argument, of course. What it does suggest is a modified SRP scenario, in which new probes first examine local stars for good candidate planets, and then only visit these. Ironically, while not every star is visited in this scenario, ours definitely would be.

The point is that there's a lot more to be said about these ideas.

Cheaper how?

Posted by Anonymous User at Dec 03, 2011 05:32 PM
Haven't read the paper yet, but cheaper in what sense? Giant telescopes at lensing locations are obvious extremely expensive, and even city-wide resolution is still way worse than going into orbit and getting resolution down to inches and feet. How do the costs scale? The point of the self-replicating probes is that after you make the first batch, they're free, I thought, while any giant telescope will quickly be limited and continue to cost money/energy for every time you use it.


Re: Cheaper how?

Posted by Bruce Cohen at Dec 05, 2011 12:47 AM
You can build the telescopes by sending out intelligent probes based on the same technology you use for the interstellar SRPs, but with considerably less payload and fuel load. IIRC, the lensing locations using the sun are about 500 AU out; it would be nice if you could find the material to build the scopes out there, but even if you can't depend on that, you can build factories for the scopes and probes using autonomous robots in the asteroid belt where metals and volatiles are easy to find and launch from there.

Alternately, use smaller scopes in solar orbit in pairs and groups as parallax imagers and interferometers. A Neptune-orbit sized interferometer should be able to image detail on a planet within at least 30 lightyears, I'd think, and that's hundreds of solar systems.


Posted by Thomas Andrew at Dec 07, 2011 04:06 AM
Greetings. I wonder about the idea of SRP. Is the premise that these devices would travel at something less than light speed? If so, and if civilizations have a finite lifespan, would they be able to get far enough away from their point of origin to find anything that couldn't have been learned by sensing instruments at home...before the civilization died or lost interest? And if the civilization had a practical FTL drive, would they send SRP or people? It's a personal view but I wouldn't willingly send a device to explore if I could do it in person, so to speak.

Somehow I have the image of these devices travelling away from their point of origin and sooner or later falling out of contact with their creators. Assuming that they are made sufficiently stealthy, do they then travel forever, acquiring data that their creators will never see? How sadly ironic if the last trace of a civilization was the probes sent out to explore.


Posted by mark wilson at Aug 06, 2012 10:10 AM
given the speed of light is not an issue for communication( entanglement) and the use of biological forms for structure of the craft and dark energy as power then the abilities are endless. think of how nature can cloak itself, how nature can evolve. We are talking way out of the box. We would just pass off the alien contact as a natural "ball lightning" event or a jelly fish in our atmosphere just feeding on ions and ozone and pooping out oxygen.

We are the SRP's?

Posted by Mirik Smit at Nov 30, 2011 06:30 PM
Well, what about panspermia? What if we ARE the SRP's?


Posted by Karl Schroeder at Nov 30, 2011 08:00 PM
Sure, in the extreme instance where we identify ourselves simply as life, rather than just as the human species. This is similar to the ultimate choice of the Chixulub in Permanence.

Or we just can’t see them...

Posted by Max Kaehn at Nov 30, 2011 08:57 PM
Given current speculations on femtotechnology, I have to wonder if the probes are already here, but too small for us to notice.

One notion I came up with years ago was that since perfectly compressed information is indistinguishable from noise, a species saturating its local electromagnetic spectrum for lightspeed communications might be hard to distinguish from a star.

incommensurability and indeterminacy

Posted by Lee Malatesta at Dec 01, 2011 01:15 PM
I think a judicious application of a bit of Duhem, Quine, Kuhn, Feyerabend, or van Fraasen would be a bit more parsimonious then positing that technology moves towards the appearance of natural objects.

Put simply, the presupposition made in Fermi's paradox is that alien artifacts are observable from within our current paradigm of science, conceptual schema, worldview, or whatever one wants to call it. But there are many possible reasons why this might not be so. That their technology may be so advanced as to be indistinguishable from nature is one reason why this may be so. It could also be that their mode of life is simply so foreign to the way that we look at the universe that we are simply unable to detect sentience within it.


Posted by Karl Schroeder at Dec 01, 2011 08:16 PM
Yes--but to say we are "unable detect sentience in it" means that it appears natural to us, i.e., not artificial. Unless you mean that there could be artifacts that are recognizably technological in origin but not recognizably artificial? Aren't these ideas the same? (Not, that is, in philosophical terms, but in terms of how we would classify them when encountering them.)

Not quite

Posted by Lee Malatesta at Dec 02, 2011 12:24 AM
When a bona fide scientific revolution occurs, explanatory increases in three ways.

1. Previously inexplicable phenomena are now explicable.
2. Existing phenomena are re-interpreted in a new and more complete fashion.
3. Previously unknown phenomena come to light.

If I understood your thesis properly, it most accurately describes (2). While I think a hearty debate could be had as to whether it describes all of (2) or not, I'll concede for the purpose of discussion that it does cover all of (2).

(1) is a bit more problematic. If by "natural" you are going to include phenomena previously written off as "instrumental error" or "background noise", then you've got (1) mostly covered. But I'm not really convinced that this does justice to the way scientists work. An anomaly isn't necessarily construed to "natural." It's, simply put, inexplicable. In fact, an anomaly might be presumed to be an artifact, an artifact of our own instrumentation!

But (3) can't be argued to be "natural" in any way because the observations are entirely new. From the old paradigm, these phenomena were simply unobservable. It takes a shift in the way that phenomena are observed (or an improvement in instrumentation) to make previously unobservable phenomena observable.

So, your thesis is one way our present state of knowledge might underdefine the way things are relative to extraterrestrial life. But it is not the only possible way that things might be underdefined.

I get it

Posted by Karl Schroeder at Dec 03, 2011 02:15 PM
Ah, now I see what you're saying! Yes, that's an excellent point, and you're right it opens up new possibilities that have nothing to do with the binary categorization of artificial/natural. Thanks.

Thank you for reviewing my paper

Posted by Anonymous User at Dec 01, 2011 10:16 PM
Thank you very much for your kind and thoughtful review of my paper. I'm glad it's getting some attention.


Keith Wiley


Posted by Karl Schroeder at Dec 03, 2011 02:21 PM
Well, if I hadn't jumped on it, one of my peers would have. For me, it was interesting because it puts a final nail in the coffin for my own assault on the Fermi Paradox (as described in Permanence); Milan Cirkovic did some fine work dissecting my selectionist approach but SRPs do a better job of getting around it.

I think the major contribution your paper makes is to point out that, if we can think of a way around a particular limitation to spreading throughout the galaxy, then 'they' can too--so what is required in addressing the Fermi Paradox is more *design*. We should be designing ways to do it, and designing around the so-called 'solutions' because, if we accept that alien intelligences do exist, this is precisely what they will do.

Lem's 'New Cosmogony'

Posted by Anonymous User at Dec 02, 2011 05:12 AM
Very interesting idea, I mean revision of Clarke's Law.

Lem in his 'New Cosmogony' said something alike this, heaven't you read it?


Lem always gets there first

Posted by Karl Schroeder at Dec 03, 2011 02:16 PM
I have read the New Cosmogony, but not for a while. You're right, that's essentially his message there, he just didn't sum it up in a pithy aphorism. Now you have me thinking about Lem, who's by far the most relevant SF writer for our current world. what fun!


Posted by Anonymous User at Dec 27, 2011 10:21 PM
Lem's books "Golem XIV" and "His Masters Voice" are also quite relevant to this discussion.

More background on Fermi

Posted by Anonymous User at Dec 02, 2011 09:33 AM
Karl, David Brin here signing in as anonymous.

Self-Replicating probes go way back. Indeed, at the Los Alamos conference on Interstellar Migration, back around 1982, I worked with Jones and Finney suggest that ONE such probe might fill the galaxy with it descendants in just three million years. An eyeblink that really pushes the Fermi Question hard.
(Circovic cites this paper.)

I doubt you've seen my 1983 paper on The Great Silence. It happens to STILL be the most thorough on the topic, even till now. In fact, it's the only truereview article about alien contact ever published. Quarterly Journal of Royal Astronomical Society, fall1983, v.24, pp283-309

Ranking the possibilities by plausibility is fun, but still pretty airy stuff.

Ever see my story "Lungfish" with 40 different types of SRPs? It'll be incorporated in my new novel EXISTENCE>

Keep up the good work.

 With cordial regards,

David Brin

In fact, my paper cites The Great Silence

Posted by Anonymous User at Dec 02, 2011 04:10 PM
Did you read my paper or just Karl's article (which I think is a fine review)? I would love to hear your thoughts on it.


Hi, David!

Posted by Karl Schroeder at Dec 03, 2011 02:25 PM
I haven't actually read the Great Silence paper, you're right. I shall check it out. Wiley clearly has, though. I do think he's made a major contribution by addressing ideas like percolation theory and by putting SRPs back on the table.

Contradiction: Fermi Paradox versus "UFOs can't get here."

Posted by Anonymous User at Dec 03, 2011 03:01 PM
One thing that bothers me about the "Fermi paradox" - it is contradictory to be astonished "why aren't they here" implying they should be, but then use "they wouldn't be able to get here" as an argument against the ET theory (that some ...) of UFO sightings! Sure, "why do they run around and scare people on farms at three AM and never contact the 'authorities' ..." but that isn't the point: it's the *argument* that they wouldn't be able to get here, versus the argument they should be here.

And sure, easier for robots than live beings, but then maybe the "real UFOs" are robotic and whatever you would imagine is responsible for the alien sightings anyway if you *are* a UFO skeptic, is the explanation for that.

- Neil Bates

Why Expand Infinitely?

Posted by Anonymous User at Dec 03, 2011 05:46 PM
But if we're going to believe in SRPs, why the very naive assumption that any civilization wants their SRPs to expand endlessly? Consider the following factors:

We don't want our probes to annoy the neighbors, who may be territorial, paranoid, greedy, or possessed of some other quality which means they would decide to make war on us once our probe started using their solar system for building materials. (One relativistic bomb can ruin your whole day.) This means that probes will be discreet and stealthy, and they won't eat too many resources the local civilization might want.

We don't want probes to expand beyond a distance where they could successfully send data. (Yes, I know probes could relay for each other, but at limited bandwidth/interstellar distances congestion problems multiply.)

We don't want probes to use all the available resources, thus taking them from us during our next step of expansion. Absent really amazing nano, an interstellar probe would be very large and use many rare substances. Assuming stealth, we don't build laser farms (they are not stealthy due to large size, infrared emissions, robots digging up asteroids, etc.) Further the probe must be able to maneuver independently, which also means no laser farms.

If we must (sigh) assume SRPs, the instruction set probably looks something like this:

Go the next star system away from Earth. Make sure it does not have intelligent life. If so, report back to us then leave he area at once. (At the very least, we'll want to transmit the latest stealth designs to the probe and have it build those before we explore that system.)

If there is no intelligent life, plant your replication factory on a discreet place well away from the local star. Then begin more serious explorations. The replication factory makes five copies of the original probe, then pushes the asteroid it is based on into interstellar space so it can't be found by anyone, then acts as a router for its ancestors and descendants.

If you are more than 100 light years from Earth, do not replicate, stop and request instructions.

Assuming we don't explore brown dwarfs we end up with around 500,000 1,000,000 highly stealthed probes in an area of more than 4,000,000 cubic light years. Detectability is NOT assured.

Two quick thoughts

Posted by Andrei Timoshenko at Dec 03, 2011 06:42 PM
On Re-wilding, in order for sentience to evolve, must there not be an advantage to sentience over non-sentient nature (whether in its pre-sentient state, or its functionally indistinguishable, re-wilded post-sentience state)? Wouldn't a condition in which non-sentient nature is inferior to sentience at a certain class of problems (namely those with *very precise* desired outcomes) be required for the emergence of the latter? If so, wouldn't re-wilding to the point of indistinguishability necessitate the giving up of these advantages? Put otherwise, we do not really ever see (or expect) evolution backtracking onto itself so precisely as to erase all vestiges of intermediary developments. Dolphins, for instance, quite clearly are not sharks...

All of which actually also leads to my second point, more related to the Fermi Paradox.

I think think the core concept underlying Re-wilding is spot on – non-sentient nature does do almost everything right. By the argument above, this leads to only a very, very narrow scope for the emergence of intelligence or sentience. If an organism can get by well enough without intelligence, there would be no pressure for it to evolve towards intelligence. And if an organism cannot get by well enough without intelligence, chances are its evolutionary branch will die off before it gets there. As a result, while hundreds of millions of species have probably inhabited the Earth at one time or another (hence, life should be relatively common) we are the only ones to be sentient, and our closest relatives, the Great Apes, aren't exactly the evolutionary success that, say, cockroaches are (so, to some extent, we lucked-out to evolve intelligence because we were a failure in every other way). Thus, while Earth is probably not so rare, could we not be grossly over-estimating the f_i in Drake by virtue of nature almost always being able to generate solutions which are superior to even 'magic' levels of advanced technology (let alone basic rock-on-a-stick)?

In other words, the incredibly perceptive observations that led you to the re-wilding of sentience, lead me to to the incredible rarity of the emergence of sentience in the first place. It's just simpler and more efficient that way! ;-)

Also, I'll admit to having only recently been exposed to (actually, through a very serendipitous reading of Son of Suns, before which I had little interest in sic-fi... or futurology – so thank you!), and, therefore, only a very dilettante grasp of these topics, so forgive me if I am rehashing old territory here...

Curious for Kalr's answers

Posted by Attila Szegedi at Dec 07, 2011 06:33 AM
I think Andrei raises some very valid questions -- would love to hear your take on them, Karl!

Re. Two Quick Thoughts

Posted by Karl Schroeder at Dec 14, 2011 04:03 PM
To the first point, sentient beings must be sufficiently fit to co-evolve with their peers; but that in no way means that they need to have an "advantage" over any other life form. In any case, my argument in Permanence has to do with the use of technology, rather than with sentience or intelligence as such. I confuse matters a bit with my language, but that's the crux of it: technological use has not yet been proven to be superior to direct adaptation *over the long term.* Yet there's no reason why technology couldn't be tried to varying degrees by many species; in fact, it is (eg. ravens build tools). When considering creatures like ravens, in fact, the balance of the evidence suggests that technology supplementing but not replacing direct adaptation is the best strategy.

To the second point, there could be other evolutionary pressures than tool-use driving increasing sentience; this seems to be the case on the Earth, because the increase in cephalization over the past hundred million years or so has not been driven nor accompanied by increased use of tools. We're the startling exception. Once again, it's tool-use that is the issue. Of course, we could be the leading edge of a "Cambrian explosion" of tool-use on Earth, but we can't know that at this point. So you're right, but the rare term in Drake's equation would not seem to be intelligence as such, but tool-use. It's not wise to conflate those two qualities.


Posted by Richard York at Dec 03, 2011 07:21 PM
I don't believe it's been mentioned here but, I do think the following is relevant.

Given all the factors mentioned so far, direct contact between Kardashev Level 2 and up civilizations will be difficult. As you've said, the sheer numbers make it difficult.

More importantly, when it comes to detection, any deeply compressed signals coming from technologically advanced civilizations may well be indistinguishable from noise. SETI may even now be hearing such signals but, without the appropriate algorithms, we will never know.

When it comes to sentience, one needs to keep Peter Watts' Blindsight in mind. Antonio Damasio has posited the existence of non-sentient intelligence. It's a concept which is very difficult to get one's head around (kind of like quantum indeterminacy) but, some really smart folks have discussed it.

Great discussion.

Rick York

Non-sentient intelligence?

Posted by Anonymous User at Dec 05, 2011 04:00 PM
I'm not sure that makes any sense at all -- Peter Watt's story seemed to me to be just nonsense.

First of all, what is sentience? It's either the old meaning, which just means awareness. Then it applies to people and cows and fish -- anything with a nervous system. The other choice is the abuse of sentience, where someone merely means "self-awareness".

Now, how could you have a high-level of intelligence without have "self-awareness"? If we eliminate souls & ghosts, "self-awareness" merely means a self-model. Any entity that is highly intelligent and interacts with other highly intelligent entities is obviously going to have a model for themselves. How the hell else can you play chess? Even the stupidest min-max checkers player has a self-model.

So what do you have left? A highly intelligent entity that lacks a self-model because it never interacts with any other intelligent being. Why would it be intelligent? Can't imagine what selective force could both make an entity "intelligent" in any way we would call intelligent and yet not give it a self-model.

Microsize Me!

Posted by Derek C. F. Pegritz at Dec 03, 2011 07:54 PM
The "Rewilding" concept is an interesting extension of the basic principles governing biomimetic design applications...but I still don't buy it as a reason we haven't found evidence of large-scale nonhuman technology in our Galactic neighbourhood (by which I mean, more or less, the Orion Arm of the Milky Way). I *do* think that biomimetic--and, by extension...uhhh, naturomimetic?--design is a necessary *feature* of extremely advanced technologies, specifically micro- and nanotech. However, if a technologically super-advanced civilization is largely composed of nanotech devices or other technological artifacts built on a tiny scale (and by tiny I mean anything smaller than, say, a moon or any other body large enough to be spotted by its EM radiation or inferred as being there due to its gravitational effects), then spotting that civilization at a distance of even a handful of lightyears would be INCREDIBLY difficult. It would, in effect, be like trying to spot a particular handful of dust in a nebula.

I tend to think that extremely advanced civilizations wouldn't even necessarily be interested in mega-engineering projects, because those kind of efforts aren't even worth considering when you can manipulate matter at the molecular or subatomic level. A Matrioshka brain doesn't *have* to be a giant cloud completely encompassing a star--it could be a wire-thin belt around the waist of a gas giant, a hoop of billions of quantum microprocessors basking in the abundant power of a jovian flux tube. Dyson spheres, in fact, and other megascale engineering projects seem to me to be a profligate waste of matter that can be better used.

I fancy that the reason the entire galaxy hasn't been swamped with robot probes is simple: advanced civilizations quickly realize that colonizing other star systems and exploring the wastelands of interstellar space is pointless. Once a civilization goes fully-digital, or produces a machine-based successor civilization, it becomes trivial to explore nearby star systems using billions of tiny, disposable probes. But why waste the time and the matter when a telescope will show you that the surrounding systems are full of planets prettymuch like those in your own system? Unless there's a life-bearing world nearby that's worth checking out--provided you have any interest in other lifeforms by that point--exploring other stellar systems is a pointless exercise when you've got plenty of matter and energy here in your Home System to fuel processing for millions, if not billions, of years? In other words...if you're living on an oasis in the middle of a boring, hostile desert, and you can see through your spyglass other oases more or less just like your own all around, why bother investigating them? All you're going to find is more examples of terrain you're already familiar with.

But, of course, any star or planet has a lifespan, even if it's a long one. What does a digitized, micro-scale civilization do when its power sources are reaching the end of their productivity. Simple: pack up and move en masse to a single nearby oasis (that is, energy-rich stellar system) where you set up shop just as you did before. Even if your civilization decides to metastasize and move to *many* nearby systems, the only things distant observers would be likely to see is what appears to be clouds of warm dust blowing away from a dying star.

Why would you expect to see them?

Posted by Anonymous User at Dec 03, 2011 08:16 PM
SRPs would not be designed to be noticed. I don't expect they'd be exactly stealthed, bute they wouldn't be designed to be noticed. And they wouldn't come in close to the sun. Analysis from a distance is much cheaper than digging yourself out of a gravity well. They get all the resources they need from the Oort cloud. I've got to presume at least controlled fusion...but I don't feel that's too much of a presumption. And given that I'm talking about Self Replicating Probes, they don't need a fast inter-system drive. So they probably never hit more than 0.05c, and perhaps even slower.

Colony ships are a real interesting case. My assertion is that they will also be travelling relatively slowly, though possibly as fast as 0.1c. But after a bunch of people live in an environment for that long, they won't be eager to get out and rough it. And they have all the tools and equipment that the SRPs do, so what they'll do is build a couple of larger and fancier colony ships and move off again. We won't find out that they've been here until we discover strip-mined asteroids out in the Oort clouds.

So why would you expect to notice that they were around?

... from Nature.

Posted by Anonymous User at Dec 03, 2011 09:07 PM
" ... any sufficiently advanced technology is indistinguishable from Nature " ( Olaf Stapeldon said this )


Posted by Karl Schroeder at Dec 03, 2011 10:12 PM
Can you provide a citation for this? Because I may have cryptomnesia, but I don't recall it coming from him.

Momentary lapse of evolution

Posted by Anonymous User at Dec 03, 2011 11:24 PM
Broadcasting the existence of your species seems more a sign of arrogance than intelligence.

By Extension:

Posted by Anonymous User at Dec 04, 2011 01:34 PM
One 'could' argue that a natural system isn't just on a macro scale, If any sufficiently advanced technology is indistinguishable from Nature, then planetary systems and indeed galaxies 'could' be constructs by this definition.

But this is an enigma, which suggests that humanity is lacking the crucial perception to recognize its existence as part of an advanced civilization. Are we faulty in some way or is the expression of baryonic life one of the pursuits of this sentience ?

In context of this discussion, humans and biological systems make for great self replicating probes. :)

zoo hypothesis

Posted by Anonymous User at Dec 06, 2011 04:58 AM
In light of the track record of advanced human culture meeting less advanced cultures.. and that every contact has been dismal for the junior partner.. the Zoo Hypothesis or a variation on that theme is as likely as jumping to the 'we are alone' at this stage of the game. With the Universe almost 14billion yrs old and technological humanity only a few thousand years old or even less .. depending on your defining moment of technology... it wouldn't be at all difficult for a Billion or Million or 100k year old empire/race/federation/whatever to keep us in a sphere of incommunicado to be doled out with tid bits of information leaks as they see us fit or able to handle them.

The only deepening paradox is the insistence of calling the universe empty after only a few decades of feeble and human investigation.

Would SETI find us, even now?

Posted by Anonymous User at Dec 06, 2011 01:49 PM
That's about it, really :-) The "window" when we were broadcasting in all directions at high power and low compression is coming to a close after about 100 years? Another 50, and I doubt much of what we send will have any obviously discernible carrier, and it will be highly directional and highly compressed. That's just extrapolating current technology, and saying nothing of complete changes of technology.

Assuming other civilisations (or we) will build things with interstellar visibility reminds me of an old cartoon I saw of a future house where everything in it was powered by a single huge electric motor up in the attic with motive energy fed out by a system of belts :-)

Still, it's good to speculate! The re-wilding idea is cool.

  - Benjohn

Intelligent design

Posted by Anonymous User at Dec 06, 2011 10:46 PM
aaaaand so: the universe was created by sufficiently advanced beings, so that we are simply living on the proof that fermi was wrong....

Brain-pops aside: I think there might be something to someone mentioning Kuhn earlier, that the fermi paradox resides on a specific understanding of "technology" and "natural"... Which your idea in a way is an expression of tackling. Thanks for that.

/David Birk
twitter @abekonge


Posted by Anonymous User at Dec 07, 2011 10:33 AM
@David: "aaaaand so: the universe was created by sufficiently advanced beings, so that we are simply living on the proof that fermi was wrong..."

The thing with Fermi was the Paradox, not the yes/no to aliens. Still I value the proposition that we're literally running around on intelligent ground. My sense is that something doesn't quite add up though, if intelligence had/has already excelled so completely then why go through the rigmarole of nursing evolution along on Earth? Maybe a bit like we can nurse a plant to see how it grows and feel proud if it makes it through a few years?


Dark Matter is the no emission hiding place of alien technology and probes

Posted by Anonymous User at Dec 07, 2011 04:36 AM
Dark Matter is the no emission hiding place of alien technology and probes

Going with your conjecture that advanced civilization's technology would not be visible by their emissions becuase they would be ultimately efficient and have no emissions to discover that means...

Dark Matter is the no emission hiding place of alien technology and probes.

The other thought I have often had is alien technology would be on the nanoscale. Why would you create larger probes if you didn't have to? a network of nanoprobes could act as any kind of resolving focusing array imaginable.

Lastly think entangled electrons. A network/aray of quantum electrons entangled with pairs in a far and distance world would be the ultimate surveillance network.


Lastly think entangled electrons. A network/aray of quantum electrons entangled with pairs in a far and distance world would be the ultimate surveillance network.

Posted by Anonymous User at Dec 07, 2011 04:38 AM

Lastly think entangled electrons. A network/aray of quantum electrons entangled with pairs in a far and distance world would be the ultimate surveillance network.

furthermore an advanced civilization would likely have discovered how to make entangled electrons pop out of the subspace in any location they needed without "traveling there" in the 3d space sense.



Posted by Anonymous User at Dec 08, 2011 07:09 AM
"Lastly think entangled electrons. A network/aray of quantum electrons entangled with pairs in a far and distance world would be the ultimate surveillance network."

According to the laws of quantum mechanics, it is absolutely impossible to use entangled particles for faster-than-light communication. The paper that proved this (assuming QM as currently understood is correct, of course) is at

Cloaking technologies...

Posted by Anonymous User at Dec 09, 2011 05:41 PM
You have an excellent point in terms of dark matter as a possible hiding place for alien probes.

Another possiblity that hasn't been explored in this excellent discussion thread are cloaking technologies. Given our own rapid advances in this field it would seem to me that any sufficently advanced civilization could use this type of technlogy to cloak not only probes but achieve this on a macro-scale and hide all radation from their home system(s). In fact, given the previously mentioned typically less than positive outcome for the junior partner in an encounter between civilizations, any advanced civilization might in fact rush towards hiding their existence as soon as possible in order to mitigate the risk of a hostile take-over. At our current technolgical trajectory, we might get there within 100-200 years ourselves - thus keeping our non-cloaked broadcasting window down to less than 250 years of outside observability - a mere blink of an eye on the cosmological timescale. It would thus be exceedingly rare to be able to catch another developing civilization just during this very short window IMO.


strange model

Posted by Anonymous User at Dec 07, 2011 04:41 AM
The past 100 years of human development is a spec compared to the 1 billion years life has been on this planet (give or take). Why assume that it is representative of life elsewhere when it doesn't even represent life here? Why assume that it is indicative of what life is like elsewhere? That is statistically improbable.

Simulation Argument

Posted by Anonymous User at Dec 07, 2011 06:06 PM
The first colonizing civilisation to arise in each galaxy colonises it and engineers it for longevity and efficiency ie something like Matrioska brains. Everyone else evolves in simulations, and they all seem to have the universe to themselves. The really ugly ones get deleted and the really nice ones are invited up for tea and biscuits and to meet the neighbours - Dirk Bruere

Rare Earth

Posted by Anonymous User at Dec 08, 2011 07:06 AM
Thanks for the link to the paper, haven't read through it yet but looks like it'll be interesting reading. I just wanted to comment with a nitpick on one issue in your post: you wrote "So one central argument against the existence of alien life--the 'rare Earth' argument that environments to host it must be rare--has been more or less disproven"--but I think you are actually misunderstanding the nature of the "rare Earth" argument here. The argument is not that planets with broadly Earthlike conditions--rocky, water-bearing worlds in their stars' habitable zone--are rare, but rather that there are a bunch of plausible candidates for <i>additional</i> conditions beyond this (like a planet where continental drift continues indefinitely, or one that has a large moon to stabilize the tilt) that would be needed to have an environment stable enough for <i>multicellular</i> life to evolve and flourish. Ward and Brownlee's hypothesis was that broadly Earthlike planets with microbial life may be quite common, but multicellular life could nevertheless be exceedingly rare, rare enough so that there'd be no other worlds where it evolved in our galaxy (I do wonder to what extent it's plausible to extend the self-replicating probe argument to intergalactic travel though...could one design a self-replicating probe that could go dormant for hundreds of million or billions of years while coasting from one galaxy to another?)

Thanks for commenting on my paper

Posted by Anonymous User at Dec 08, 2011 04:32 PM
Thanks for commenting on my paper. You're absolutely right that it is conceivably possible to send probes to other galaxies. The reason I don't consider it relevant to the Fermi Paradox is that the travel times are high enough that the argument that they haven't arrived yet is more valid, unlike in the intragalactic example. In fact, as I argue at the end of the paper, we should make some effort to look for signs of intelligence in other galaxies specifically because the Fermi Paradox doesn't inform us about them one way or the other.



Posted by Anonymous User at Dec 10, 2011 12:18 AM
I've read the paper now, it's excellent! I'll have to refer people to it whenever I get into discussions of this subject. On the subject of other galaxies, even though the travel time is large, could considering this issue be used to put some further constraints on the likely probability of technological civilizations arising if we assume self-replicating probes are feasible, and that there's a good chance that civilizations capable of building them would be interested in building very long-term ones to send to other galaxies? In this case we could consider something analogous to our past light cone, except with the boundaries defined not by the speed of light but by a plausible estimate for the speed of intergalactic SRPs, call it our "past SRP cone". If we assume few if any civilizations capable of building SRPs have arisen in our past SRP cone, wouldn't that give a much more stringent upper bound on the probability of such civilizations arising in any given star system, lending strength to the Rare Earth hypothesis? The number of stars in our past SRP cone should be quite a bit larger than the number of stars in our galaxy. Of course, you can't extend the cone back too far, because for life I think you need a second-generation (or more) star system with a lot of heavy elements produced by a previous star's supernova, and I don't know how rapidly the number of heavy-element star systems would decline as you go back to times before the birth of our own solar system, maybe the chance of a civilization existing even a few billion years before ours would be drastically lower. But if not, extending our past SRP cone out a few billion years back would end up including a vastly larger number of stars than exist in our galaxy, suggesting civilizations may be very unlikely indeed.

Rare Earth

Posted by Karl Schroeder at Dec 14, 2011 04:09 PM
The Rare Earth camp's theories are increasingly falsified by the current planet-hunting effort. Although nobody can speak to the likelihood of life itself coming into being, much of their argument actually does have to do with the likelihood of finding life-friendly environments in the galaxy. The likelihood of finding moons around Earth-like planets is an example of this; but recent studies provide a probability of approximately 12% for an Earth-like planet in the habitable zone to have a moon large enough to sustain its rotation; and even without that, spin-axis wandering doesn't seem to be as bad a problem as it used to be. This goes also for the likelihood of a planet maintaining a strong magnetic field, for the climate of tidally-locked planets, etc. The many problems they refer to in their book have mostly been systematicaly eliminated since it was published.

Re: Rare Earth

Posted by Anonymous User at Dec 14, 2011 09:26 PM
<i>but recent studies provide a probability of approximately 12% for an Earth-like planet in the habitable zone to have a moon large enough to sustain its rotation; and even without that, spin-axis wandering doesn't seem to be as bad a problem as it used to be. This goes also for the likelihood of a planet maintaining a strong magnetic field, for the climate of tidally-locked planets, etc.</i>

OK, I thought you were talking about direct observational evidence like the Kepler mission, but it sounds like you're talking more about theoretical studies (since Kepler hasn't told us anything directly about the moons of Earthlike planets, the magnetic field, or the climate). Can you point me in the direction of the studies? And "Rare Earth" mentioned quite a variety of conditions other than the ones you brought up, like the need for continuing plate tectonics, the danger that a typical Earthlike world may get locked into a "snowball Earth" type state, the possibility that without a Jupiter-like gas giant at the right distance the planet may get hit by huge mass-extinction causing asteroids too frequently, etc. I doubt that we can say anything very non-tentative about whether the overall claim--that the conditions needed for long-term evolution of multicellular life may be very rare--is correct or not.

There's also the possibility that even if the conditions aren't that rare, there may be a bunch of evolutionary "hard steps" required to get to organisms like us that are each fairly unlikely purely in terms of typical evolutionary pathways, so even if you rewound history and played things out again on our own Earth they probably wouldn't all happen again. Have you read Hanson's "Great Filter" paper? It's at: or[…]/greatfilter.html if the original page doesn't load (it wasn't loading for me just now). One interesting aspect of that paper is his "safecracker" argument (a variation on an argument Brandon Carter made in a 1983 paper listed in the references) suggesting that if there are a bunch of hard steps on the way to intelligence (like the origin of life, the origin of eukaryote-like cells via symbiosis, the origin of sexual reproduction, the origin of multicellular life) then on the small subset of planets where they do all occur, even if their probabilities are fairly different we should expect them to be about equally-spaced in time. And what's more, probabilistic arguments suggests that if each step takes about X years, the final hard step (probably the evolution of a language-using intelligent species capable of technology) should typically occur about X years before the point where it'd be too late (either because life dies out, or biodiversity declines steeply). If you take the Cambrian explosion as one hard step, and the evolution of intelligence as another (or possibly some landmark between the two, like the evolution of the amniotic egg), you get the conclusion that if we hadn't evolved when we did, the Earth would probably only have in the neighborhood of another 500 million years to evolve intelligence before it'd be too late. That may seem far too short given the lifetime of the Sun, but as discussed in Ward and Brownlee's "Life and Death of Planet Earth" (though they don't make the connection to the anthropic argument above), it turns out that via geophysical processes the increasing brightness of the Sun has been creating a long-term trend towards decreasing CO2 in the atmosphere, and it's expected that CO2 levels will get too low for plants to continue carrying out photosynthesis in around 500-800 million years, and meanwhile that "biological productivity" (the rate that inorganic carbon is turned into biological molecules) should continually decrease until then, perhaps making the evolution of intelligence 400 million years in the future much more unlikely than it would be now. So, I think this is suggestive as a possible piece of "evidence" for the Carter/Hanson "hard steps" model.


Posted by Anonymous User at Dec 08, 2011 10:33 PM
If the inidications are that there shoudl be zillions of other civlilizations out there, and they theory is they have all re-wilded back into somethign we cannot differentiate from nature...

Then I don't buy the theory at all. It would seem that it would require that we exist in a strange period of time where all other civilizations are either so young as to be unobservable, or so old as to have returned to unobservability.

I don't have the math, but what are the odds of that particular situation being true? I would think, given an expected large number of other civilizations, we should be seeing them all throughout the lifecyle - some becoming noisier or more observable (as we are) and others busy fading from observability.

So, unless you leave occam's razor even more in the read view mirror and postulate some previous civilization achieved a rewilded state before we started looking, and then used its technology=magic powers to rewild everybody else in the universe except for us... We are alone.

Re. Huh?

Posted by Karl Schroeder at Dec 14, 2011 04:13 PM
There was a paper on just last week about this... but I'm having trouble finding it right now. It's about the probability of our being in a position to receive messages at the same time that any alien civilization is broadcasting them. The probability is fairly low, even for a galaxy that's constantly overflowing with young active civilizations.

self-reproducing probes and sustainability

Posted by Anonymous User at Dec 09, 2011 09:00 AM
Why don't we see billions of SRPs?

3 possibilities for novels:
1) SRPs are undetectable
2) we are incorrectly interpreting their presence (as dark matter?)
3) SRPs do exist but have some inherent limits to their population density, which were put in place by their creators to protect the universe from a run-away spread of SRPs; echoes here of the computronium visions of converting the universe into "useful" components

Thanks for commenting on my paper

Posted by Anonymous User at Dec 09, 2011 05:39 PM
In my paper I specifically address the topic of run-away SRPs and suggest that the threat is probably very very low. Therefore it is unlikely to be a motivation for intentionally handicapping an SRP mission.

More to the point, suggestion 3 prescribes an unjustified homogeneity of motive and behavior across presumably thousands or even tens of thousands of utterly independent and alien species and societies. I don't find that very plausible. Such a theory only accounts for the subset of SRPs missions that follow its precepts (apoptosis, forcibly imposed by the creators), but it does not account in any way for the numerous remaining missions (assuming vast heterogeneity of mission design) that do not incorporate intentional probe death, especially in light of the fact that run-away SRPs notions are realistically very unlikely in the first place.


"anthropptropic" media evolution

Posted by Paul Levinson at Dec 10, 2011 10:23 PM
I agree completely with your "My revision says that any sufficiently advanced technology is indistinguishable from Nature," Karl. Indeed, this is what I had in mind when I developed my "anthropotropic" theory of media evolution back in 1979 ("Human Replay: A Theory of the Evolution of Media," PhD dissertation, New York University") - which argues that, as media (and by extension, all technologies) evolve, they get increasingly natural not artificial (black-and-white photography gave way to color, silent movies replaces by talkies, etc). Your application of this to the Fermi paradox, however, is original and brilliant! For more recent (than 1979) discussions and applications of my theory, see just about any of nonfiction books - The Soft Edge (1997), New New Media (2009), and these blog posts[…]/anthropotropic%20media


Posted by Karl Schroeder at Dec 14, 2011 04:19 PM
Thanks for the comments, Paul. I'd like to find out more about it; the link you added takes us to your website but not to any article specifically talking about the idea. I'll try a general Google search...

the Anthropic Principle angle?

Posted by Jim Moskowitz at Dec 11, 2011 02:25 AM
While I don't hold in high regard the various levels of Anthropic Principle about which I've read (which seem to me to transition from tautological statements to mystical faith-based ones with precious little interesting intermediate levels), I do want to know if you have thoughts about what I think the A.P. implies regarding the Fermi Paradox:

Just as we must conclude that we're living in a universe capable of creating conscious organisms, because we're here, and no universe that isn't capable of generating conscious life can ever have that question asked in it... is it possible to conclude that we're the first life form ever to reach the technological level we're at, because only the first ever gets to ask "where is everybody?" -- every later-developing civilization already has probes there (if it's even able to develop after the First Civ deals with it)

Anthropic reasoning

Posted by Anonymous User at Dec 11, 2011 06:38 PM
I think you're using the anthropic principle in a way that *is* purely tautological--by the same logic, no matter what bizarre observation we are confronted with (say, a "thermodynamic miracle" like a shattered egg spontaneously reassembling itself), we could always say "only the tiny fraction of individuals in the multiverse who happen to make that observation will be able to ask 'why did I just observe that?' so there is really nothing to explain!" In that way, one could "explain" absolutely anything.

The way the anthropic principle is actually used is not so obviously tautological, IMO. Nick Bostrom is a philosopher who's written a lot about the anthropic principle, you can read an introduction at ...his basic point is that anthropic reasoning should be based on something he calls the "self-sampling assumption", which says that we should reason *as if* we were randomly selected from the "reference class" of all observers. (But he points out that there is some room for debate about the exact nature of the reference class--all "conscious" beings including animals? All "humanlike" intelligences? All intelligent beings capable of formulating questions about their situation and engaging in probabilistic arguments? But definitely the reference class would not consist of all observers who whatever precise observation that you just made, or it would be tautological.) The case that this sort of assumption seems compelling in certain situations is illustrated in the following thought-experiment in the "Doomsday Argument FAQ" on that page:

"A firm plan was formed to rear humans in two batches: the first batch to be of three humans of one sex, the second of five thousand of the other sex. The plan called for rearing the first batch in one century. Many centuries later, the five thousand humans of the other sex would be reared. Imagine that you learn you’re one of the humans in question. You don’t know which centuries the plan specified, but you are aware of being female. You very reasonably conclude that the large batch was to be female, almost certainly. If adopted by every human in the experiment, the policy of betting that the large batch was of the same sex as oneself would yield only three failures and five thousand successes. ... [Y]ou mustn’t say: ‘My genes are female, so I have to observe myself to be female, no matter whether the female batch was to be small or large. Hence I can have no special reason for believing it was to be large.’ (Leslie 1996, pp. 222-23)"

Suppose you were a member of this experiment, and the evil creators of the experiment told you that you were required to guess the sex of the larger batch, and if you guessed wrong or refused to guess at all they would kill you (they also mention that they chose which sex was the 3-person batch and which sex was the 5000-person batch by the flip of a balanced coin). With your life depending on getting the right answer, wouldn't you be inclined to use the self-sampling assumption here, and figure that if everyone bets the larger batch was their own sex, then 5000 of them will live while only 3 will die, and there's no reason to think of yourself as "special" so it makes more sense to bet this way yourself? In spite of the fact that a priori (before using any anthropic arguments) it seems either answer has a 50% chance of being correct?

The Deepening Paradox

Posted by Stephen Michael Stirling at Dec 13, 2011 02:00 AM
Wouldn't Occam's Razor suggest that the most parsimonious explanation for the absence of evidence of advanced civilizations is simply that there aren't any?

After all,-someone- has to be first. Although we're not actually launching any probes yet, we have created evidence of our existence detectable at intersteller distances (eventually).

The scenario would run: most worlds capable of supporting life don't produce any; most life-supporting worlds don't get beyond very primitive organisms (Earth didn't for a long time, after all); most worlds with complex organisms don't get sentience; most worlds with sentience don't produce civilizations; most civilizations never get to their equivalent of the Scientific Revolution; most that get to the Scientific Revolution don't survive long (after all, we might not).

For various values of "most".

Hence, we're the first one in this galaxy, or nearly the first -- there might be others just getting started.

As the saying goes, someone has to win the lottery.

On being the first

Posted by Karl Schroeder at Dec 14, 2011 04:23 PM
Of course! Yes, *of course* the most parsimonious explanation of the Fermi paradox is that we're the first. But that in itself has huge implications and raises more questions than it solves. What we have here is a bare field where there should be a jungle. That's highly suspicious, even disturbing, and demands an explanation. Yet nobody has one.

The Fermi Paradox

Posted by Anonymous User at Dec 16, 2011 04:31 PM
There is a possible biological explanation for the paradox:

John Lambshead

The Deepening Paradox

Posted by Stephen Michael Stirling at Dec 16, 2011 07:51 PM
Pardon if this is a repeat, I'm not sure if I posted the first attempt.

>But that in itself has huge implications and raises more questions than it solves.

-- I don't see why. My hypothesis, -if true-, solves everything quite neatly.

That something is low probability doesn't mean it can't happen; it just means that it's less likely. Low-probability events happen all the time. No matter how bad the odds, someone will always win the lottery.

>and demands an explanation. Yet nobody has one.

-- I gave a hypothesis, which accounts parsimoniously for all the observable facts.

Why multiply hypotheses? We're just re-masticating the same data set. We need more information, or we're just tossing around non-falsifiable ideas.

If true, my hypothesis also solves a lot of other 'questions'. For example, the Paradox now says absolutely nothing as to the practicality of self-replicating probes, FTL, or anything else. These things just haven't been tried.

It also means in the very long term that we have a clear run at the field and that we're extremely important.

Begging the question

Posted by Anonymous User at Dec 17, 2011 05:24 AM
To say "there should be a jungle" assumes your conclusion, I think. The counter argument is that we shouldn't expect a jungle of multiple species and civilizations. Precisely because SRP are so powerful, we should expect the first spacefaring civilization to sweep its galaxy in an evolutionary eyeblink, and perhaps beyond, like bacteria in a fertile petri dish. It's not bare field vs. jungle, but bare field vs. monocrop that excludes competitors. If we can evolve, we're in the bare field.

Another angle: this rebuts the Copernican principle of assuming mediocrity, of our middleness in a distribution. That only works if there's a non-degenerate, ideally somewhat normal, distribution, for us to be selected from. If the distribution of civilizations is [1], then our getting this far suggests we're it. We *are* the middle. And first, and last.

I don't think it's suspicious at all, or raises more questions. It solves all the questions. It's just not emotionally satisfying, if you want there to be aliens out there.

As for Rare Earth, a pessimistic view of Earth's history could suggest that it's more common for there to be total mass extinctions along the way, and we're the lucky case where life never got totally set back, just had close calls. "Life is common!" but so are mass extinctions, some of them near total. With only one data point it's not really testable.

Of course, we're hardly out of the woods yet, still vulnerable to methane burps and supervolcanoes and mucking up our own environment. But that would still fit there being only one galactic civilization someday... just not us.

On Begging the Question

Posted by Karl Schroeder at Dec 28, 2011 04:04 AM
My point is that we don't actually have any reason to think that we should be alone. We have the apparent observation that we are alone, but absent a reason why it should be so. So, yes, that really IS a big question. It's not remotely sufficient to say 'life is rare.' WHY is it rare? The Rare Earth hypothesis isn't holding up well according to the current data and associated theoretical models. Although we don't know how life started, it's not looking that unlikely either. If these things weren't puzzles, there would be no Fermi paradox. They are puzzles, and deep ones, and cannot be dismissed by simply taking our uniqueness at face value.

Virtual Reality

Posted by Anonymous User at Dec 19, 2011 11:04 PM
I'm surprised there's no mention of another possible explanation of the great silence. The possibility that we are not, in fact, inhabiting the real universe. We are, rather, inhabiting something else's virtual reality or simulation.

It's probably pointless speculating on the motives of that entity which lead to the creation of our virtual reality. One possibility is that it is descended from creatures like us, and wants to find some answers about its own ancestors.

Maybe it wants to know what would have happened if we hadn't discovered the SRPs with which its own solar system was liberally sprinkled?!

virtual reality

Posted by Stephen Michael Stirling at Dec 20, 2011 02:27 AM
The possibility that we are not, in fact, inhabiting the real universe. We are, rather, inhabiting something else's virtual reality or simulation.

-- that is a non-falsifiable hypothesis. It can't even be theoretically disproven; anyone running such a simulation could simply edit it to prevent us from doing so.

It's like the argument that the world was created .5 seconds ago, complete with all the evidence of 13.5 billion years.

That is to say, it's not just wrong, it's -worse- than wrong; it's a semantic null set.

virtual reality

Posted by Anonymous User at Dec 20, 2011 11:58 PM
Non falsifiable - certainly, what's the problem? Godel proved that every self-consistent formal system contains unprovable but true propositions. You can't actually prove that the world wasn't created 0.5 seconds ago. You can only wave Occam's razor at the hypothesis, or say that the hypothesis lacks any predictive power compared to accepting the evidence of 13.5 billion years of history as real evidence of real past events.

At a future time, the virtual reality hypothesis might become the simplest and most acceptable under Occam's razor, if the programming is less than perfect. We might spot evidence of the bugs or approximations in the simulation.

As of now, VR is an oddball hypothesis with little to support it, but it does provide one possible explanation of the great silence.

Great Silence

Posted by Anonymous User at Dec 21, 2011 08:21 PM
Non falsifiable - certainly, what's the problem?

-- I agree with Popper; there's simply no point in discussing a non-falsifiable hypothesis.

You can't actually prove that the world wasn't created 0.5 seconds ago.

-- I don't have to.

Sufficiently advanced

Posted by Anonymous User at Dec 30, 2011 07:07 PM
We are already on the cusp of cloaking materials in ever-widening ranges of the electromagnetic spectrum, and are probably at least 100 years off from viable SRPs, and who knows how many millenia from our first dyson sphere. Taking our paranoia over the unknown into account as probable for any sufficiently advanced life, why on earth do we keep assuming that these highly advanced civilizatins will not be self cloaking? Especially if it just means patterning the outside of the sphere or probe with a fractal metamaterial pattern.

We're close to using quantum entanglement for communications (i'd say about the time we can make SRPs), so assuming advanced civilizations take a tech trajectory similar to ours, looking for electromag as signs of their civilizations, we'd only detect them in a 200 year span of time in their pre-celestial exploraton period.

A couple of thoughts

Posted by Anonymous User at Dec 30, 2011 07:47 PM
SRP may or may not be possible, it remains to be seen if we ever will build one.
The point that they are most efficient ways to explore universe doesn't seem that likely. Telescopes can be used to pinpoint candidates for life and even image alien planets-you could then simply send probes to the areas you want to, without wasting time on other solar systems

Here is a funny idea about whole galactic life imager, although I am not certain that it is completely possible:[…]?disc=159729;article=102431

Ultimately I believe the Fermi Paradox to be more of an reflection of certain early technological mindset from the era when we expected mountains to be moved, rivers diverted, and continents engineered.
Logically moving the stars, dyson spheres and immense radio signals to all other stars would be the next step. But as we develop we minimize our influence on the environment, and colonization has been stopped(nobody is settling Antarctica and some islands in Pacific have been abandoned although they are habitable), instead of spreading we concentrate in urban areas. Perhaps similar paths will be reflected scale.

In the end the answer to Great Silence probably will be banal, the distances in time and space are too great for communication, SRP's are too wasteful method and too inefficient or perhaps even unworkable, and our extend of observation of universe was limited(maybe in 100 years with better astronomy we will discover some astro-engineering or city lights on other exoplanet)


Extrasolar Angel ;)

Dyson Spheres-interesting

Posted by Anonymous User at Dec 30, 2011 07:57 PM
Also I forgot to add that contrary to popular belief about no possible signs of alien civilizations, there have been searches for Dyson Spheres, and they actually DID find ambiguous candidates.[…]/Other_searches.htm[…]/Fermilab_search.htm

Of course the general opinion is that these are some kind of stellar objects, but nevertheless they are considered candidates.

does this mean...

Posted by Anonymous User at Jan 09, 2012 10:52 AM
that water-bears/tardigrades are probably alien data gathering probes? Cos it is a bit odd to mostly live on moss while also being able to survive in outer space.

missing point

Posted by mark wilson at Aug 06, 2012 10:07 AM
given the speed of light is not an issue for communication( entanglement) and the use of biological forms for structure of the craft and dark energy as power then the abilities are endless. think of how nature can cloak itself, how nature can evolve. We are talking way out of the box. We would just pass off the alien contact as a natural "ball lightning" event or a jelly fish in our atmosphere just feeding on ions and ozone and pooping out oxygen.

The new explain of Fermi paradox

Posted by Anonymous User at May 27, 2013 12:50 PM
Why we are so alone in the universe,this is impossible in’s always confused us for a long time.but if we solve the following qusetions.maybe we can find the answer obviously.
Can we read our memory from our brain by some kind of technology?and can we write it to a new brain of a new body we make it by genic technology or others.let’s assume it’s there are a series of questions coming.they are divided three parts.
Part one: personal
1:if your memory have been removed,who are you?
2:if your memory have been replaced another one’s memory,who are you?think this question carefully,you can image that when you wake up in every morning.
3:do you think the memory actually is your soul.( It doesn't matter if you don’t think so)
4:do you want to prolong your life by this way that read and write your memory?if not,how about the time you will die very soon.I think if I will died and I will try it because I have nothing could be lost.
Part two:Human
1:if someone among us want prolong their life by the way read&write memory,does their life have huge advantage to normal person.because they are immortal,they can choose their body and etc.
2:if 1% person in the world want prolong their life by this way,can they finally replace all human’s life form like now .
3:if you can be immortal and change your body if you live in the world a few thousands years after.what do you think about the meaning of the live.I have thought this question and I get a result that we will become observer from participator for nature.just watch,hear and feel the running of nature.
4:can you image where the genic technology or other technology lead us to.the standard of body we choose is more strong, pretty or simple but can receive enough information from the nature that we can feel it better to be a observor.
Part three: nature
1:why every one in the earth thought they have soul and the soul is they real one had ever seen or heard it.whatever they have different faith,education,nationality or etc.why this theory is infused into every one’s brain?can we define it is instinct.and every intelligent creature in the universe like or better than human have this instinct?
2:if we calculate the length of human civilization from the birth of words.there have already been a few thousands years till now.let’s assume we will be observer within 5000 years.(it’s a very long time for human).so current human civilization is totally ten thousands years. The extinction of the Dinosaurs had occurred 66 million years ago.then you can image a scene that you have a book have 6.6 thousands pages.the kind of civilization of human just is one page among it.and we look for it in infinite space and time.the chance that we meet is very impossible.
3:we all aware not every creature can be intelligent like human.human thing just is occasionaly maybe other “human” had appeared in the earth in other page.we just dose alien.the civilization like human that we look for just is a transition stage from participator to observer,the length is very short for the universe.and if we become observer,we just feel the running of the nature.don’t want to interfere in it.
4:if we don’t like this future,can we stop it?I don’t think so.because no one can stop the science go forward.and there must have someone to try it when the read-mind technology is matured.
5:Is there other way we can go?no,because the memory is the only answer for the soul,not DNA,face or something else.and the soul is human real one can deny if we can ,we must do.
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About Me

I'm a member of the Association of Professional Futurists with my own consultancy, and am also currently Chair of the Canadian node of the Millennium Project, a private/public foresight consultancy active in 50 nations. As well, I am an award-winning author with ten published novels translated into as many languages. I write, give talks, and conduct workshops on numerous topics related to the future, including:

  • Future of government
  • Bitcoin and digital currencies
  • The workplace in 2030
  • The Internet of Things
  • Augmented cognition

For a complete bio, go here. To contact me, email karl at kschroeder dot com

Example: The Future of Governance

I use Science Fiction to communicate the results of actual futures studies. Some of my recent research relates to how we'll govern ourselves in the future. I've worked with a few clients on this and published some results.

Here are two examples--and you can read the first for free:

The Canadian army commissioned me to write Crisis in Urlia, a fictionalized study of the future of military command-and-control. You can download a PDF of the book here:

Crisis in Urlia

For the "optimistic Science Fiction" anthology Hieroglyph, I wrote "Degrees of Freedom," set in Haida Gwaii. "Degrees of Freedom" is about an attempt to develop new governing systems by Canadian First Nations people.

I'm continuing to research this exciting area and would be happy to share my findings.


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    A Young Adult Scifi Saga

    "Lean and hugely engaging ... and highly recommended."

    --Open Letters Monthly, an Arts and Literature Review

    Sheer Fun: The Virga Series

    (Sun of Suns and Queen of Candesce are combined in Cities of the Air)

     “An adventure-filled tale of sword fights and naval battles... the real fun of this coming-of-age tale includes a pirate treasure hunt and grand scale naval invasions set in the cold, far reaches of space. ”
    Kirkus Reviews (listed in top 10 SF novels for 2006)

    "With Queen of Candesce, [Schroeder] has achieved a clockwork balance of deftly paced adventure and humour, set against an intriguing and unique vision of humanity's far future.
    --The Globe and Mail

    "[Pirate Sun] is fun in the same league as the best SF ever has had to offer, fully as exciting and full of cool science as work from the golden age of SF, but with characterization and plot layering equal to the scrutiny of critical appraisers."

    "...A rollicking good read... fun, bookish, and full of insane air battles"

    "A grand flying-pirate-ship-chases-and-escapes-and-meetings-with-monsters adventure, and it ends not with a debate or a seminar but with a gigantic zero-gee battle around Candesce, a climactic unmasking and showdown, just desserts, and other satisfying stuff."