All the responses saying “Maybe they are avoiding us because we’re made of meat” or “Maybe they avoid us because of the Prime Directive” misses the part of the Fermi paradox that there should be lots of advanced civilizations out there. The civilizations on Earth can’t agree on anything, there is no way I can believe that every advanced extraterrestrial culture out there chooses to avoid us. There has to be another resolution to this paradox.
I’m of the opinion that intelligent life is much much rarer that we could possibly think, and that interstellar travel (and/or communication) is much much more difficult. And then you’ve got billfish’s “rowboats in the Atlantic” analogy, which I like very much. Space is unbelievably huge (there’s a Hitchiker’s guide reference in there somewhere but I’ll let someone else quote it), and technology can’t overcome everything.
If they really are a billion years ahead of us, it’s worse than that. We think the first insects appeared during the Silurian, the beginning of which was only 443 million years ago. That’s not even half a billion years. A billion years ago, you’re talking unicellular life.
a) We are in our infancy. A mere 10,000 years ago we weren’t even leaving written records behind. If our species had 14,217,000 years of fairly complete recorded history, we would be in a somewhat better position to say “If they exist why haven’t we run into them yet?” but at the moment it’s a bit like saying “I’ve been waiting for space aliens to contact us since 5 PM, where the heck ARE they?”
b) There’s a reason people use the adjective “astronomical” to refer to incredible scales of size and distance. When our species is in its 14,217,000th year of civilization, I would not be terribly surprised * to discover that we still don’t have the technology to scoot around amongst the stars and colonize planets orbiting other stars and explore the galaxy and whatnot. We may never discover a fuel source sufficient to propel us at sufficient speed to make even the tiniest of exploratory journeys feasible.
c) The corollary to b is that if the next 10 million years or so of technological advances do give us the stars, they will probably also usher in revolutions in communication technologies as well. Just as our neolithic ancestors could not have made note of hypothetical advanced civilizations using radio broadcast signals, we could be fully unable to intercept whatever communications modalities are in use by the types of species that flit around the galaxy colonizing and exploring planets.
well, except for my astonishment at my own longevity, I suppose
That works if the assumption is there is only one or two other intelligent civilizations out there. But, in a universe with an infinite number of possibilities the odds of every single other civilization having significantly different motives from us is highly unlikely, IMO.
It only takes one civilization like us to fill a galaxy in 10-50 million years.
There’s also the assumption that we ourselves are going to colonize that galaxy if things go well but that’s a hell of an assumption. By the time we have the power and technology to go out colonizing, colonizing could well be a silly outdated concept.
Well, it only takes that long if you’re not the one doing the colonizing – if you’ve got a sufficiently powerful spaceship able to maintain a constant acceleration (something like 1 g for convenience) for a long enough time, thanks to special relativity, you can pretty much get halfway across the visible universe in your lifetime; nevermind that a gazillion years pass ‘on the outside’.
However, I think that, as technology advances, it becomes less and less important to actually physically go anywhere – something the beginning of which we’re starting to see right now: video conferences instead of flying all the way to China, virtual/augmented reality, interplanetary missions completed by robots creating virtual experiences of other worlds with the data they send back (mostly pictures and videos at this point, but I’ve heard Huygens descend through Titan’s winds, too), heck, message boards!
So, I’m not really sure there ever will be a need to colonize the galaxy – explore, maybe, but that can be done with small, automated probes; those same devices could also be used for communication (in the form of Bracewell probes), seeing how any direct interstellar communication takes far too long to be feasible, generally, which probably means that nobody bothers sending jiggawatts of radio energy just off into space in the hopes that somebody listens.
Indeed, if I wanted to explore the galaxy, make contact in the best feasible form with other intelligent lifeforms, that’s what I would do: Build a Bracewell probe possessing full artificial intelligence (alternatively, upload/copy my own intelligence into it, should such a thing ever become feasible), have it be able to replicate itself in the manner of a von Neumann probe, and just send it on its merry way, with the instruction to seek out candidate star systems with worlds on which intelligent life might evolve (in lieu of directly encountering any alien life, in which case a contact could be made immediately), and settle comfortably in some Lagrange point, just waiting around to be discovered.
This, I think, explains both flavours of the paradox – they aren’t here because they don’t really go anywhere anymore, and we don’t hear them because they aren’t talking (the way we expect them to, at least).
Of course, another possibility would be that whatever they do is much more advanced compared to the things we do then what we do is to what Homo Erectus did, and hence, there isn’t even the possibility of mutual understanding, but that’s just no fun to speculate about.
Yeah, but what is Drake’s equation, except Fermi’s Paradox written down as a pusedo-equation? I always figured Drake’s equation was what Fermi was trying to say, too many semi-known variables ruin your ability to make predictions.
Yeah, but well before you reach the speed of light, you run into issues like (a) how much fuel you can bring and (b) the fact that running into sparse interstellar hydrogen atoms at 1/10 of the speed of light can do some serious damage. If you don’t take biological life along, you can save yourself a lot of mass and get a lot further, but I’d still want some heavy shielding (which would have to be, you know, heavy) for my AI core if I was going to have hydrogen atoms shooting at me at 1/10 the speed of light (never mind .99 c) for several years.
Well, given that the energy of a hydrogen atom at 0.99 c is about 10[sup]-9[/sup] Joule, I think appropriate shielding can be constructed.
(Snark aside, your point is obviously correct when it comes to even slightly macroscopic objects, small dust grains or micrometeorites; but I don’t know the appropriate population numbers in interstellar space, nor do I have any clues as to what kind of impacts one can effectively develop shielding against, so I’m not even gonna speculate on whether or not this is going to be an insurmountable hindrance to interstellar travel.)
Well, just packing up a single ship and sending it on its way would be a daunting task, but thinking big and long-term a fleet of power stations and electromagnetic or electrostatic ram scoop spaceplows could be deployed in advance of lighter, faster, safer ships.
Well they touch on the same general subject, sure. But I believe Drake was specifically trying to estimate how many alien civilizations we might hope to detect, by radio signal, as we started an earnest search for them. Fermi, in contrast, was arguing that there’s been plenty of time by now for any one alien civilization to have colonized the whole galaxy, yet we see no sign of this having happened — which strongly suggests (to Fermi anyway) that the aliens simply aren’t out there at all.
I’m glad at least one person mentioned Von Neumann and Bracewell probes! here’s a good link. At any rate, our machine offspring are far more likely to explore the universe than we ever are, although with our DNA, they could certainly reconstitute us wherever they go if they’d want to.
I’ve wondered if somehow Dark Matter / Dark Energy might just be the glow of a vast universe-spanning civilization. (Counter to that there is this though.) Maybe one that can exist away from stars and create matter and energy ex nihilo the way virtual particles and antiparticles pop up and annihilate each other from the vacuum energy. Or perhaps the majority of stars are surrounded by concentric, nested Dyson Spheres and are perfect blackbody objects.
I’ve also wondered if the entire universe is just one of many that was purposely created for the purpose of studying how civilizations develop and expand. In this case we could intentionally be the only planet with sentient life in the universe. Or, perhaps the study is to see how civilizations interact, in which case there may be a few others. Wouldn’t it be fascinating to observe how two space-faring civilizations first come into contact and what happens afterwards? Maybe even do some interventions along the way to keep them at roughly the same technological levels until they do meet? It could even be a form of art!
Everyone has heard the old if one in a million. . . . etc. arguments for other intelligent life. No one likes to do the math the other way.
I did it, in a thread a while ago.
Here it is again.
Suppose a trillion civilizations, in the universe have each been expanding for an average of ten thousand years. Suppose these civilizations expand at the speed of light. Suppose further that this state of affairs is more or less constant, with new civilizations replacing fallen ones over the fifteen billion years of universal history. So, where are they?
Well, given that:
(1.5 x 10[sup]10[/sup])[sup]3[/sup], x 4/3 pi = 1.413 x 10[sup]31[/sup] cubic light years in the universal neighborhood.
And these trillion civilizations occupy
4.189 x 10[sup]24[/sup] cubic light years,
the percentage of space occupied by those civilizations is
I’ve highly suspected for the longest time that our universe and us in particular were created by the Nth dimensional equivalent of FOX network executives. That or Ted Turner.
That’s true. And there’s a finite amount of time since the Big Bang; even if you argue that there must be some civilizations much older than we, they can only realistically be so old (and have had time to evolve).
If the speed of light truly limits communication (let alone actual expansion) of even the most advanced civilizations, then it would be extremely unlikely for us to have found any yet. We’ve been looking an extremely short time, and through extremely limited means.
It’s not really feasible to determine how much life there is, let alone speculate on intelligent life. Who knows what life that evolved on the other side of the galaxy would be like? We have only one closed system to examine.
Lastly, I think the issue of priority is an important one. It’s not a particularly large priority here, to us, in isolation, to search the galaxy, in terms of expenditure of resources; if there were civilizations meeting each other, isn’t it likely (based on what we know of life) that they would be competing for survival? Why is the universe like Star Trek and not like nature that we know (red in tooth and claw)? Given the huge barriers to communication and the (presumable) natural urges to survive, there’s no reason to assume that advanced civilizations cooperate peacefully. Unless one species had dominance of their area of influence, as we do of our planet for the most part, maybe they just don’t have the time to spend on matters that don’t increase their chances to survive. We don’t believe the universe to be all that hospitable, really; what if life-bearing planets are extremely rare commodities? Look at what we do to each other over limited resources here, and that’s with our own species!
Unnatural spectra. That’s what I will look for, when I win the lottery and found the elucidator Institute for Deranged Research. Stole the idea from Larry Niven, in his Protector book, where Phss-ptok searches the skies for evidence that the bad guys are coming for him. He looks for spectra that would derive from likely propulsion systems, shifted either red or blue, depending on relative trajectory, towards or away.
Then we would know that they’re out there, and that they travel. Not information that goes into the Useful category, but sure fits well in the Cool! category.
True, but civilizations are unlikely to be equidistributed within it – most will probably have originated within galaxies. Estimates vary, but there are probably about 100 billion galaxies within the visible universe, and, if our galaxy serves as a benchmark, each of those has, on average, a volume of around 4 * 10[sup]13[/sup] cubic light years, making for a total habitable volume of around 4 * 10[sup]24[/sup] cubic light years, which, according to your calculation, should all be rented out by now.
or “Maybe they avoid us because of the Prime Directive” misses the part of the Fermi paradox that there should be lots of advanced civilizations out there. The civilizations on Earth can’t agree on anything, there is no way I can believe that every advanced extraterrestrial culture out there chooses to avoid us. There has to be another resolution to this paradox.