- It takes a very short time in comparison to the age of the galaxy for a single self-replicating probe to result in a descendant probe visit to every star. A few million years. This means that you cannot really argue plausibly that all civilizations fail to do this - it would take trivial effort for just one faction within just one advanced civilization to set this underway. It's quite clearly the case that we will do it when we can.
- There is a proposal I recall reading that suggests all colonization/self-replicated expansion is patchy in a sort of fractal way. You're always going to get sparse frontiers and empty real estate.
- The Great Filter.
- The Simulation Argument (Bostrom variant).
- The Drake Equation
- Where are the macrostructures? We don't see Dyson spheres or other evident macroscale engineering. Everything we can see so far looks natural. This is more troubling than an absence of detectable communications. There are any number of ways we can think of for interstellar communication networks to exist and yet be undetectable by us at the moment, and then there are no doubt all the ways that we can't think of.
- Agents responsible for the Fermi Paradox through suppression of nascent intelligence are a popular science fiction trope. First one to the top kills off the rest as they turn up. (Berzerkers, Wolves, etc). It makes for good plotting, but in reality this suffers from all the same issues as economic monopolies and monocultures - i.e. without some sustaining outside influence they are fragile and short-lived, prone to defection, being undercut, and out-innovated from a blind spot. So it's not plausible to suppose that we are randomly in a period of suppressive monopoly.
The scare quotes for advanced here are that two incompatible definitions for civilization quality compete for the nominative "advanced." In the current context advanced means we've developed machines that carry us into space, we can create habitats to survive in even when our surrounding habitat is inhospitable and we leverage natural resources to create excess food. An alternative context for "advanced" is that your civilization exists in balance with the other processes on the planet, you don't create anything that that wouldn't be created by natural processes inherent in the system, and your resource utilization is at a rate that does not exceed its replenishment rate. Further you explicitly do not use any resource that is not naturally replenished.
In the context of that dichotomy, the question might be "Why didn't the Dinosaurs develop space flight?" They lived on the planet for millions of years before we got here, there is evidence that their cognitive capacity was at least as large as ours, and some species had the ability to manipulate matter at least as well as our paleolithic ancestors did. So why didn't they build giant Dinosaur cities, grow Dinosaur food, and build institutions of higher learning? Depending on your timeline we went from struggling ape to SpaceX in 3 - 5 million years. They had 165 million years to figure it out. Why were they even on the planet when the asteroid hit, and/or why didn't they do something about it before it hit? Using Dinosaur lasers or something.
Depending on how you count we've gone through 5 to 7 nearly total extinctions on this planet. What made this last one special? What is the key set of things that have to be true in order for life to go from being intelligent to manipulating everything around it in its environment to serve the will of that intelligence?
They are complex questions. Great fun to contemplate on camping trips, while under the influence, and when you've run out of other 'safe' conversational starters.
There might be billions of worlds full of dinosaur analogs running around happily eating and growling till their star burns out...and that might be all that you can expect out of life in the general case when it happens.
"Why didn't the Dinosaurs develop space flight?" Why don't we? Again, in absolute terms of the characteristics we're requiring of an alien civilization, we're not really any closer (in measurable absolute terms) to visiting Vega than a struggling ape is. The furthest distance a human has ever traveled off of the Earth is very slight navigational/rounding error when going to another Star.
"There might be billions of worlds full of dinosaur analogs running around happily eating and growling till their star burns out...and that might be all that you can expect out of life in the general case when it happens."
This is the essence of the Fermi paradox I believe. (And I've ordered a copy of the book mentioned below, it looks intriguing) So what hypothesis could support billions of iterations of 'life' evolving into the multicellular form we see today and in our past, and so few evolving technology?
I totally agree it is a somewhat useless question to ponder but I can't help it.
Probably just a function of environmental input and enough generations optimizing along directions that matter more for species propagation than a large, energy burning cognitive organ. Keep in mind, it appears that Human level intelligence seems to have (so far) only evolved maybe a handful of time maximum in planetary history...and AFAWK only along a fairly specific mammalian family line that happened to live on part of the planet with fairly specific thermal/environmental and energy availability properties.
On a planet slightly warmer than the Earth, the dominant species might be selected to have heat management organs we're not even aware of; or a planet with more landmass vs. ocean, the ability to handle dry climates; or a planet with two moons and higher gravity an efficient metabolism and ambulatory system...some kind of reptilian slug perhaps?
Are savannas necessary to culture space faringness? Or could a planet with no moons, shotgunned with equally dispersed Guam sized islands provide the necessary conditions?
It's useless, but an incredibly fun thought experiment.
Philosophically, even an Ark ship, with technology capable of sustaining a population of humans for a million years wouldn't fit the bill since I'd argue that by the time the descendants arrive they:
a) would probably not be the same species anymore, having evolved over thousands of generations for ship life
b) wouldn't be the same civilization anymore, having developed their own micro-civilization in the intervening years -- they'd no longer be representatives from their home civilization...any more than I as an American can be a representative for the European civilizations I am descended from when I travel to Asia
c) their home population and civilization will have evolved and diverged from the Ark's population and civilization regardless of the Ark's conditions. Even if the population on the Ark was put into some kind of suspended animation for the length of the trip (preserving the both the original species and civilization) they'd be representing a species and civilization that no longer existed
There is a hyper specific (perhaps overspecific) theory by a geologist named Matthias Kuhle with many publications from vaguely the 80s thru the 90s. He's probably the most "famous" of the proponents of the whole plate arrangement theory.
The general idea that plate tectonics causes the overall cycle of ice ages doesn't seem very controversial. What the geologist types seem to fight over a lot is Exactly which of numerous causes contributes Exactly what percentage of the positive feedback loop in Exactly which numerical model.
For example Kuhle has a lot of publications about the tibetan plateau being a great place to bootstrap the glacial positive feedback loop. There's others who get all excited about the precise location of the continents affecting the flow of ocean currents pushing warmth up north... The current that pushes warm water to England so its warmer than alaska, the current that used to flow over Panama but can't anymore, the current that used to not exist over the Bearing straits in Alaska but exists now. Then theres the other folks who get all wound up about continents being over a pole (like antarctica) or landlocking a polar ocean (like the other side, the north pole) leading to glaciers. There's something of a minority opinion about "really big continents with mountains in the middle covered in glaciers"... think America's Glacier National Park as visual model, other than its all melting right now.
I don't know anything about the book you linked to, although it's reviews make it look interesting.
The other possibility is that there's not much more technology for us. Can we build self-replicating probes that can operate, without maintenance, for thousands of years? No we can't.
So we have this wacky set of assumptions -- that alien civilizations will be more advanced than us in certain peculiar ways (able to build self-replicating probes and/or Dyson spheres) but not in others (having the primitive needs and side-effects that we do). This is a tiny corner of a very large set of possibilities.
Maybe the aliens simply build new Universes to order and leave their birth universe behind because it's (a) less hospitable than their new "air conditioned" universe, and (b) it's unethical or boring or pointless to colonize a universe full of new potential civilizations.
Folks need to read some less mainstream SF. I like Clifford Simak's "City" where the vast majority of the human race emigrates to Jupiter to live as hunter-gatherers (because Jovian life is so much more pleasant than human life) leaving Earth to the dogs, robots, and ants.
Or think about actual humans, something large that we'd recognize as a starship, and a vast amount of antimatter. Much more spectacular, and much less likely, because of the amounts of energy involved in getting the job done - and all that just to ship things that could be build on site.
The point being that even if you say that we'll never build self-replicating technology (which is essentially the same as being a vitalist) then given the time scales involved - if every step in the probe network takes 1,000 to 10,000 years of resting time to build a complete organic human civilization before kicking off the next series of probes - it still requires a short time span to visit all stars in the galaxy in comparison to the age of the galaxy.
The idea that you can seed the universe with civilizations in the manner described is highly dubious. You're assuming someone advanced enough to do this yet primitive enough to want to do it and that "it" works at all. Suppose that the galaxy produces one star system in a thousand with a suitable planet, and the seed has a one in a thousand chance of actually producing a successful replication. (Both of these one in a thousands seem to me to be quite optimistic.) The equations look a lot less deterministic.
This might be a stupid question, but could the Red Square Nebula be considered a candidate? http://en.wikipedia.org/wiki/Red_Square_Nebula
Then I tidily put away the thought because I know it is not even falsifiable, I don't bother assigning probabilities like unlikely. But the short moment (following such news) of delight at contemplating exotic entities so foreign, that words like conscious and alive are inapplicable is a healthy pastime I much enjoy.
Though, I'd also put three planes intersecting the conical surface and showing off the three different conical intersections, then inscribe their equations on a planet orbiting the star at the centre.
We don't see any of these things. And the amount of "space" left in physics for some sort of true escape hatch that might let us escape fully into an impregnable universe of our own devising or something keeps going down and down.
I consider the lack of cosmic-scale engineering to be a much bigger problem than mere inability to detect signals. A lot of it isn't even that "hard" per se, because what's impossible on the year or century scale becomes feasible with only very realistic projections of what self-replicating technology can do if you can put in millions of years of continuous effort. And a lot of this stuff would both be visible, and essentially necessary; if life is so inevitable and intelligent civilizations so likely, quite a few of them will find themselves dangerously close to an incipient supernova on an uncomfortable time frame, and they ought to be doing things about that. Very visible things. It's just too perfectly quiet out there.
But it's fun to speculate since any number or combination of events might be responsible for the absence of fellow civilizations.
There is a Great Filter argument that tries to say that we're really, really, really special or that our civilization-ending event might still be in the future. Since we're speculating, I don't think the biological filter argument is very plausible. Historically, we have always been proven utterly wrong after presuppositions of specialness. On the other hand if the Filter is ahead of us, it would have to happen very soon - good candidates for this remain AI, nano tech, or plain apathy. But then again assuming these would be an issue for every advanced civilization seems a stretch.
The simulation argument only makes a difference if the simulation is specifically targeted and limited to simulating us humans. If it's just a universe in a box, it wouldn't tip the scales either way.
The Drake equation and its cousins are nice, but they contain a lot of unknowns. Still, it's a good tool that shows how easy it would be to have statistical fluctuations resulting in a dark epoch.
I personally like the Agents of Suppression theory as well. It wouldn't even have to be another civilization suppressing everything directly - it could just as well be a completely automated armada of leftover killer robots. In my opinion it's one of the more plausible hostile alien invasion-stories as well: one day, we'll fulfill a set of unknown criteria and are simply tagged for extermination. But again, they would have to come our way pretty soon, like in the next 1000 years (which is not a lot of time). This would require a pangalactic drone network for observation and a fast local strike capability. Not completely unfeasible, but not exactly obvious either.
The absence of large-scale artifacts is also interesting, but we have to ask ourselves if we could even detect, say, a ring world or a Dyson sphere if it was in our direct neighborhood (and chances are, it wouldn't be that close). Also, intelligent civilizations would not necessarily produce them. However it would be enough if a few did build huge structures. Again, I don't think we're advanced enough to detect them (or their absence) with any confidence.
I am no expert, but I remember reading somewhere that our Sun is among the first generation of solar systems that were born with enough heavy elements to make life based on carbon, oxygen, nitrogen, occasional iron etc. possible.
That there first needs to be some generations of starts going nova so that the stars have generated the heavier elements, and then the supernova explosions have to spread these around to that then the new interstellar clouds have enough of these element when they collapse to next generation stars and solar systems.
A loglinear graph tracing the genetic complexity of life reaches zero about seven billion years. Obviously this implies an extraterrestrial origin of life theory. But it would also say life came into existence half-way into the big bang expansion and has been gaining complexity ever since. We are the result of this. But there's no reason to think there are other lifes that have that much of a head start. Thus it is not surprising that the manifestations of other intelligences haven't appeared.
Perhaps gravity is the only radiation they cant hide, so all we could detect of them is 'dark matter'?
Assuming a Dyson sphere was nearby, how would we detect it? What would it look like? If it's able to make use of most of a star's radiation output, wouldn't that make it very difficult to see? It wasn't until recently that we were able to detect black holes and I'd have to guess a Dyson sphere's star would be much less massive and energetic than that.
In the end, it's certainly not impossible that a civilization would go to extreme lengths in order to hide its enormous artificial structures. But the real issue is: why would all civilizations hide in this way? And if it turns out they do all have elaborate stealth tech in operation, that means there must be an incomprehensibly huge threat out there - which in itself might be the answer to why nobody is calling us up.
Throughout the novel there's alien civilizations that use different kinds of way to cloak constructs and settlements. Examples include devices like artificial moons and holographic, multi-spectral holograms that emulate gas giants to hide stuff inside.
The one I think andrewflnr may be referring to is a device that one race used to cloak entire regions of space to hide their civilization from technologically superior aggressors. Essentially they set up variable-gravity devices at strategic points around their region of space, and had the devices resonate to build 'waves' of gravity that would constructively interfere at a massive scale at the borders of their space, which would essentially tear any intruders apart using the amplified+alternating gravity waves. Several million years in the future, observers/scientists of other races on the outside would dismiss these chaotic space regions as an unexplained anomaly.
Now the interesting question is, is the energy you capture from the star sufficient for running this cooling system of yours. I have no clue.
Not a giant leap to imagine for a species that's been able to construct a Dyson Sphere in the first place ;)
The sphere would be dynamically unstable in the gravity field of the star and station-keeping would be expensive and hard to coordinate over the lightspeed delay.
And stars are terrible energy sources--they're huge, diffuse, inefficient, and not portable. It would be much more useful to build fusion generators to order.
Some archeologist, 20 millions years hence: "Oh god, not /these/ forerunners again."
It wouldn't be all bad, being first.
Then you've got the fact that the env for coms has been becoming increasingly hostile anyway. Long term quantum computing is pretty much a certainty, and when that happens quantum encryption seems like it's going to be the only workable form of coms for anything you want to keep quiet. Even if you assume that in the West it'll only be places like NSA and GCHQ and so on who have one - China's going to have one too, and do you really think they're not going to use it against commercial systems? People will have to move to quantum encryption - you're just not going to be able to do business without it.
So, I wouldn't expect us to keep using the airwaves very much. I expect the future of airwave use to be primarily relatively short ranged point to point transmissions.
The visibility for radio transmissions, even if humans survive a million years isn't, I think, going to be a million years, I'd expect it to be more like 100. Thus - though I don't know how they calculated their number - I'd make the back of the hand odds that someone examining our planet randomly would pick us out not 1 in 5,000 but, instead, 1 in 50,000,000.
And since we're not going to get 50,000,000 civilisations within the handful of lightyears before our signals have attenuated down to the background... I'd put the odds heavily against anyone seeing us on that basis.
Whether someone will pick up the composition of our atmosphere and aim a more powerful beam in our direction I don't know. But it makes it ... something that the other civilisation would have to decide to do. And then you're dealing with - does it actually make sense to let other civilisations know that you exist? What are your potential gains when balanced against the risk of relativistic weapons and the like?
The radio detection of the earth by broadcast analog NTSC TV carriers has already ended. The article author specified it as a million years. We got about fifty instead. If the LGM are watching our analog TV carriers and the SNR is less than 20 dB or so, there is no way they'll see digital as a discrete signal, nor will they likely randomly guess the correct signalling types/codes.
The meta issue is as a species we're really good at thinking our time is special. 100 years ago watching a spectrogram of analog AM video carriers would have been unthinkable futuristic not even rational to discuss, 25 years ago it would have been a pretty good idea, today its ancient nothing but static, no body would do something so anachronistic.
This misbelief in the importance of your time is closely related to one of the funniest atheist arguments, which is so intellectually unthinkable its rarely discussed. Even the slightest gaze on religious history of the species shows that before the birth of a prophet or whatever, people really thought they had it all figured out almost as well as after. Because this mis-design-pattern has repeated itself with pretty much all religions in the past, I'm sure it will happen again in the future, so simply deciding to believe in nothing until the true prophet is born in 100000 years is the most rational decision. In fact over 100000 years we'll probably have about 100 prophets, all of which, however temporarily, being considered the last word in religion... Its sometimes called the patience atheist argument, or a few other things... Why, everyone knows the best and most important and most correct culture to ever exist, in the past, or more importantly in the future, is now, of course.
My conclusion is, if you don't see that, you're the first.
If this is true, we were likely destroyed a long time ago, and we now live in one of those simulations. Any cosmic activity outside of our solar system is a mere fuzzy approximation, and even if we develop interstellar travel technology, we'll hit some sort of "Truman Show" wall if we try to leave our imaginary sandbox.
Makes you curious to keep watching the Voyager probes, does it not? :)
You say it like it wouldn't be fascinating just by itself. About 70% of Earth's surface is covered by water and more than 90% of the ocean still remains unseen by human eyes. We don't even know what incredible creatures could be living deep in the ocean let alone on another planet!
Oh and by the way, even the fact that we can't have a "decent conversation" with other species doesn't mean they are not intelligent (whatever that means). Most people would considered dolphins stupid but it seems that they could be communicating with each other using some kind of sono-visual language and maintain quite complicated social structures.
However, as you point out, we live in the middle of an enormously rich biota need not stare at the stars to find new life forms. That's quite amazing.
We just don't know enough about all the variables, such as noted by others in this discussion the probability of evolving to sentience, to state with any confidence that we can't be the first in our galaxy or the portion of it that we're looking at.
According to whom? See https://en.wikipedia.org/wiki/Relativity_of_simultaneity
no :). That is the beauty of this Universe - global full order of things on timeline isn't possible. Specifically space-like separated events don't have a preferred order, i.e. given 2 space-like separated events A and B, both statement - A precedes B and B precedes A - have the same validity, basically it is meaningless to talk about their timeline order.
Rather than go down to Planck level granularity, if reaching space flight, or better, serious engineering works in space that are visible from afar is a low probability thing, with time scales say in the millions of years, then "first" will I think do for our purposes.
as long as special relativity is applicable, for space-like separated events A and B, there exist frames of reference such that A is at x time units after Big Bang and B is at y in one frame of reference, and A is at y and B is at x in the other frame, ie. in reversed order.
It would suggest cognitive thought or at least, competence is a "mutation" forced upon the life-form by environment(s).
Time would only play a miniscule, but essential part in that process until the life-form figured out time doesn't seem to matter too matter.
PS: Birds have limited brains because of weight issues but their neurons are just as evolved and capable as primate neurons.
Perhaps we shouldn't discount the possibility that's a universal evolutionary stage, and that there's just some sort of 'prime directive' type thing keeping any life from contacting us yet?
This doesn't really apply to the self-replication wave, but it is an argument against active SETI.
The truth is, technology is incompatible with species.
As soon as a race becomes able to competently engineer genes (or whatever serves to encode their form) suddenly there is no more 100% cohesive 'species', but also a number of self-engineering unique entities. Who's interests typically conflict violently with the remaining original species. When one or more of these entities survive they eventually become space faring individuals, wholly transcended from their original species-derived intellectual nature and physical form. Of course there are many pitfalls, and in some cases the outcome is 'everyone dies'. But in NO case, can a technology wielding species ever do so for more than a very brief period.
Space is full of intelligent life. All of whom are immortal, universe-roaming individuals, none of whom have any kind of species-survival related instinctive thought habits. There are no interstellar empires, no expand and conquer instinct-driven behavioral rubbish. Only Travelers.
And most certainly, from moral principles deriving from the fundamental nature of information, intelligence and fun, NO passing of significant information to any instances of embryonic planet-borne life forms. No more than you'd consider poking a fetus with a pointy stick. Horrible idea, nothing useful could come of such actions.
Btw, the 'Grays' are open-source gene-ware, manufactured intelligent semi-independent remote manipulator/observer peripheral units of visiting Travelers. They are not 'species', rather a range of production models. When they do interact with humans they lie about their nature and origin, since humans are not supposed to be handed the truth. It would interfere with humans' natural progression towards transcendence (or self annihilation.) The only thing that matters is that the human 'story' remains uninfluenced by exposure to external truth.
But there's nothing wrong with you working it out for yourselves.
Here's a little story: http://everist.org/texts/Fermis_Urbex_Paradox.htm
Meanwhile, we miss a bigger definition of life right under our noses. Unfortunately reductionism is ingrained in science.
Astronomers should be the first to propose that, since they know how the carbon molecules in them can be traced back to a nebula, just like mitochondria can be traced back to a life form from Earth's early days. The parallel is obvious to me.
The Gaya hypothesis, for instance, gives a saner view of how the biota and biome are the same thing, and still, gets dismissed as New Age stuff. And that's talking just about Earth, mind you. Expand the theory to the entire Universe and you will be ridiculed by Dawkins himself, even though this "hunch" is persistent.
Many past thinkers had a gut feeling about this, with less data than we have today. Read about "Anatta" (Buddha's concept of "not self"). Or read about "Tao" (Lao Zi's concept that has surprisingly parallel to what we now call "Big Bang" and how nature works out of pure probability). This is all surprisingly insightful knowledge, made out of pure intuition.
But because post-illuminism abolished holism, we end up looking for analogous of humans with radio antennas, Dyson spheres, among other increasingly ridiculous things, and that gets called science. Meanwhile, ideas like Universal Darwinism are ignored.
Well, that's why I find that amusing.
There might be billions of rockballs in the galaxy with life and intelligence at some level, maybe even up to the level of say a dolphin or a dog or even a chimpanzee on the high end. This might be the status today, or for the last hundred million years and the next hundred million. But those planets (and other orbs of lifebearing rock) aren't going to be sending spaceships our way anytime soon.
But let's suppose there's a million space capable intelligences spread out equally in the Milky-Way...what's the probability of them giving our particular system any interest whatsoever? The Drake equation is a fine estimate for the number of civilizations, but not for the probability that they'll contact us.
It would be a thrilling feeling to know that there, maybe 20 or 100 light-years away, is such a planet, hosting at least microbial or algal life.
What's great is, we're about to get a whole lot more data with which to do astrochemistry.
As a result we're sending a lot less stray analog RF out into the universe. And the stuff we are sending looks a lot more like noise.
Of course, it has taken us about 1/4 the lifetime of the entire universe to get this far, so YMMV. :D
What an absurd idea!