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New Paper Offers Additional Reasoning for Fermi's Paradox
KentuckyFC writes "If the universe is teeming with advanced civilizations capable of communicating over interstellar distances, then surely we ought to have seen them by now. That's the gist of a paradoxical line of reasoning put forward by the physicist Enrico Fermi in 1950. The so-called Fermi Paradox has haunted SETI researchers ever since. Not least because if the number of intelligent civilizations capable of communication in our galaxy is greater than 1, then we should eventually hear from them. Now one astrophysicist says this thinking fails to take into account the limit to how far a signal from ET can travel before it becomes too faint to hear. Factor that in and everything changes. Assuming the average communicating civilization has a lifetime of 1,000 years, ten times longer than Earth has been broadcasting, and has a signal horizon of 1,000 light-years, you need a minimum of over 300 communicating civilizations in the Milky Way to ensure that you'll see one of them. Any less than that and the chances are that they'll live out their days entirely ignorant of each other's existence. Paradox solved, right?"
We humans are God's only children. That's why there's no one else in the universe. And the universe was created 6k years ago. Duh! Scientists... what useful things have they ever done other than bring up heresy?
I thought it was because as they reach our level of civilisation, they built giant particle accelerators for research and turned their planets into black holes.
Maybe we are the first to achieve this capability. If life did create itself from a universe that created itself, ONE of the life forms which achieved this interstellar communication would have to be first. Why not us?
...it means that civilizations that spread out and last longer than 1K years are exceedingly rare. Which would mean that our odds of achieving any meaningful interstellar travel are quite low. (We might make a space probe or two, but like how we got to the moon but haven't done anything with it, apparently nobody puts out space colonies.) There are other posible theories, though.
PHEM - party like it's 1997-2003!
This is hardly a new idea. It's so not new that I think I remember saying something similar about two years ago, and I'm not exactly an expert.
Analog signals degrade quickly, and digital signals are worse, in their way, because they don't tolerate degrading as well. Couple that with broadcast limitations imposed by local governments to keep signal strength down, and I can't see how our signal could be reliably detected more than a few light years away without a HUGE radio antenna array.
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
And if they're communicating by some mechanism that we can't read? E.g. the equivalent of "subspace radio".
Or maybe it's a point to point via laser (see Niven's Known Universe).
Fascism starts when the efficiency of the government becomes more important than the rights of the people.
Did you read the summary? The point is that outside of our galaxy no intelligible signal is going to reach us. Therefore, the rest of the universe doesn't even enter into it.
You are using English. Please learn the difference between loose and lose; they're, there, and their; your and you're.
We humans are still a bunch of young, angsty teenagers. We desperately want to make the "first contact", crying and yelling and suffering from the depressive thought of loneliness.
Other galactic civilizations simply matured and stopped worrying about such pointless things. They make themselves busy with real business.
Grow up, humans.
Colorless green Cthulhu waits dreaming furiously.
Exactly. Maybe all those "crazy" people are actually talking to aliens.
Maybe there really is no FTL, and other alien races are as leery of sending out giant seedships that they themselves can't ride in as we are, and are thus still hanging out in their home starsystem.
Maybe aliens are everywhere, aware of us, and simply choosing not to communicate.
Disproving aliens deductively is the opposite of science. The lack of easily obtained evidence for alien life is far from damning given the area that we are capable of observing with any real scrutiny.
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
True. The calculation of 1000 years seems a bit too long. We can't figure out how to shorten it because we don't know how long we're going to be using broadcast signal based communication as opposed to some other more direct means.
Besides . . . attempting to extrapolate with so many unknowns is, at best, an exercise in postulation. At worst, it is dangerously misinforming.
Unless it's been vastly misrepresented in mainstream presentation (like TFS), Fermi's Paradox sounds pretty ridiculously simplistic.
Other bad assumptions it makes, just off the top of my head:
1. Other intelligent civilizations want to engage communications with aliens who, for all they know, might try to blow them up or eat them.
2. Those civilizations are willing to spend resources to beam electromagnetic radiation out into space in the vague hope of someone noticing.
3. Other intelligent civilizations "capable" of "communication" will follow the same technological arc as us and develop electromagnetic communications rather than, say, quantum communications or something we haven't even thought of yet.
4. Those aliens will assume that WE (or some unknown aliens) will be listening carefully for extrasolar broadcasts.
5. Those aliens even have a concept of "communication" and aren't just some hive-mind that never needed to evolve social skills.
6. They didn't cut their Alien-SETI funding to pay for medical research or an Alien-Wall-Street bailout package or something. (I mean, what do you think the chances are that WE will broadcast for a thousand years?)
And so on.
Really, Fermi's Paradox sounds like me saying that if I sit on a lonely beach for a week and don't find a bottle with a message in it in proper English, there are no other intelligent beings in the world.
"Paradox solved, right?"
No. Some planets suitable for life have almost certainly existed in this galaxy for billions of years longer than the Earth. By now, one would expect there to have been civilisations that spread throughout the galaxy and therefore brought Earth within detection range of their signals...
But they would have to be within earth's range in the last 100 years or so for them to detect us. "Billions of years" means they could have existed on Venus before humanity ever showed up, for all we know. If they were that close, the signals would have long since passed us by at the point we were discovering fire.
Or they could have been reasonably nearby, but too far for the signal to reach us without fading out completely.
Or they could be using a different form of communication than we are able to perceive.
So, honestly, "expecting" anything is a little silly and assumes far too much.
No - Those people really are crazy.
The aliens talk only to me and I have the good sense not to answer them (at least not out loud). I just carefully carry out their instructions and try to get mixed up with those crazies.
He's getting rather old, but he's a good mouse.
It's not like we're located close to Downtown Galaxy. We live out on the edge. There's probably some galactic equivalent of AT&T or Comcast that is telling everyone else "We'll be providing them with service 'soon'. So our monopoly is justified."
Either that or the installer showed up and we were too busy/unaware to answer the door. So they said they'd be back later.
Invalid Checksum. Retrying.
Not necessarily. It may just be that interstellar travel isn't feasible, the ardent wishes of sci-fi writers everywhere notwithstanding. Remember, it's never enough to simply be able to do something: it has to make economic sense if you expect to get anybody else on board, too.
Assuming you can't skirt around the light barrier then that basically means sending small groups of people (or aliens or whatever) across trillions of miles, probably in some kind of hibernated state, in the hope that they'll bump into a habitable somewhere, set up shop, and begin to populate. Any returns on investment will be very intangible indeed- physical goods have to come back the same way they came (meaning it would have to be extraordinarily valuable to merit the shipping and handling on an interstellar ark) and information is cheap. You'd need to expect a very valuable treasure-trove of knowledge indeed for information to start making sense as an expected ROI.
I know many people just assume that interstellar travel is the "next step" in the development of societies but the longer I look at it the less it seems to offer tangible benefits for the people who have to invest in this.
I expect a society thinking in the long-term would obviously see the benefits of spreading one's seed across multiple star systems... but you have to postulate the existence of a society that takes the long view. Considering how easily a society as advanced as ours (not saying we're very advanced: just a society at the same level of advancement as us) is busily undermining its own biome, knows it's doing it, and doesn't care, and took pains to smother other societies which might have taken the longer view, I don't think we should expect many societies to reach the "long-view" stage before they wiped themselves out or got wiped out.
I don't know about you, but I prefer a link to a blog over the actual paper. Mostly because I don't speak Astrophysicsese.
I went ahead and clicked on the blog for you, and the link. Here's the paper (You can get a PDF if you want), it was submitted to the International Journal of Astrobiology.
http://arxiv.org/abs/0901.3863
I understand your reluctance, after all you're the one who posted:
http://slashdot.org/comments.pl?sid=1112493&cid=26694469
Don't worry, you can continue to click on links out of curiosity. I put one above, go ahead, click it. You know you want to. everyone else is clicking it. Now with more fiber, and it cures Alzheimer's too.
Hence, gamma-ray bursts. The advanced-technology equivalent of flaming laptop batteries.
Welcome to the Panopticon. Used to be a prison, now it's your home.
The 1,000 year thing seems like the weak point of this theory. Sure, most communicating civilizations may not last more than 1k years (and this is an idea based entirely on observation of our own civilization). But as soon as you get interstellar travel, how likely is it that the species manage to die off entirely in a short span? Its easy enough to wipe out one planet, but what about the next? And every spacecraft that manages to escape?
Right now our civilization is like a closed source application running on a dev box off the network. If the hard drive dies, the code is toast. But as soon as you get that code in Git, its a whole lot harder to kill.
Ok, so that was a terrible analogy.
Hello (hello, hello)
Is there anybody in there?
Just nod if you can hear me
Is there anyone home?
(See this wiki article as an example of a slightly technical description of why)
The point is you don't need to have a population that is astoundingly wedded to the idea of spreading out across the stars. You need a tiny, tiny fraction of the population to be wedded to the idea - just a handful of pioneering types who are okay with being placed in stasis for a few centuries, or raising their children and grandchildren inside a giant hollow cylinder. If you can find 500 people every few years who are willing to do something like the above, you will eventually become a pan-galactic civilization.
If libertarians are so opposed to effective government, why don't they all move to Somalia?
The calculation of 1000 years seems a bit too long. We can't figure out how to shorten it because we don't know how long we're going to be using broadcast signal based communication as opposed to some other more direct means.
My own contribution to the debate:
As technology advances the limited amount of available bandwidth becomes more valuable, while costs of utilizing it drop. The civilization migrates its bandwidth use from simple, extremely redundant, coding schemes (like AM and FM) to subtle, highly-efficient schemes that are virtually indistinguishable from thermal noise (like OFDM). They also use spacial multiplexing to re-use the same bandwidth over and over at various locations. This buries the few redundant parts of the signal (like the pilot subchannels used for synchronizing the receiver) in interfering noise.
The result is that, after a fairly short time, at a distance they are virtually indistinguishable from a hot black body - and lost in the sagans of other hot things in the galaxy.
Our first AM voice radio broadcast was at the end of 1906. 102 years later we're taking a big step in the transition to OFDM-or-CDMA-everywhere by shutting down "analog TV" and replacing it with OFDM-based digital. AM and FM are already using digital variants to squeeze more out of their spectrum. Any bets on how long until they switch, too?
Once the simple-modulation blowtorches are switched over the few remaining detectably-patterned signals will be soft voices crying in a wilderness of high-noise-floor. If we don't DELIBERATELY send some intended-to-be-noticed beacons we'll again be lost in the background - our own and the galaxy's.
A thousand years? In our case the detectability sphere looks to be only a tad over 100 years deep.
Don't blink!
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
The 1,000 years isn't time from broadcasting to die-off. It is time from broadcasting to narrowcasting (using lasers or some other communications method that directly targets the intended receiver). Once narrowcasting is in use, we wouldn't expect to hear them unless they know we are here and are specifically targetting us.
Think about the transit time, think about the number that would be lost. You can't really assume a straight geometric progression for something so incredibly fraught.
Well, almost, at least for the purposes of ballpark calculations.
Now, we have to make a couple of assumptions -- such as that they have the technology to send out self-replicators that will last long enough to get to the next star, which is a function of speed and durability. For the sake of argument, let's assume that the Voyager spacecraft (which just left the Solar System) are capable of self-replication, have a very long-lived power supply (long half-life radioisotope, for example) and their electronics will survive long exposure to galactic cosmic rays. (All big assumptions, but imaginably within range of our technology.)
Also assume an average spacing of about five light years apart for stars.
At the current speed (about 16 km/sec), it would take a Voyager about 90,000 years to reach the next start. Allow 10,000 years for the laborious process of self-replicating from raw materials and launching another of itself on its way, for a total of 100,000 years per generation. Assume each vehicle replicates itself only twice, and stays put (perhaps assembling large black monoliths on the local planets for the mystification of any eventual inhabitants). So we have a doubling rate of once per 0.1 million years.
Assume about 100 billion stars in our galaxy (this is the number I found most frequently mentioned), it would take between 36 and 37 doublings to send a probe to every star in the galaxy (less because stars are closer nearer the core). Call it 40 to allow for probe loss.
So in a mere four million years, self-replicating probes travelling no faster than Voyager could visit every star in the galaxy -- except for the speed problem. That growth rate can be maintained initially, but like any spreading colony (such as bacteria in a petri dish) the edge of the colony can only advance at a certain speed, and the doubling rate has to fall off (it's ludicrous to think that the number of visited stars could go from half the galaxy to the whole galaxy in a mere 100,000 years, the probes would have to be approaching lightspeed for that).
Take the galaxy diameter as 100,000 light years, it'd take nearly 2 billion years for a Voyager-speed probe to cross it, or near 3 billion to go around half the circumference (to avoid the black hole at the core). The galaxy is old enough that there probably sun-like stars (our Sun being a second-generation star, necessary if you want enough heavy elements for terrestrial planet formation) a couple of billion years older than ours. (And if we assume faster travel speed, say 0.01 c instead of 0.000055 c, the numbers get a lot better.)
So Fermi's question was simply "where are they?". If they're really not around (vs simply ignoring us or being undetectable to us), then the above assumptions are too optimistic.
-- Alastair
Building a generation ship will easily be one of the most expensive and large-scale projects that our species has ever undertaken. A couple of willing colonists can't afford this alone. They need the entire population behind them.
If you want a vision of the future, imagine a youtube comments section scrolling - forever.
The 1,000 year thing seems like the weak point of this theory.
Actually, the estimate of the probability of the kind of intelligence that makes complex machines is a bigger problem, and a plausible solution to the paradox.
We have ample evidence that if a thing is possible at all, evolution will reproduce it many times. Wings, fins, eyes... all of these optima have been found many times, across genera and families and whatnot. By one estimate the eye has evolved independently a couple of dozen times, based on the proteins used in the retinal structure.
There was an article here on /. a while back pointing out that two birds previously believed to be related were the result of convergent evolution. Evolution finds the same optima over and over again.
The kind of intelligence that makes complex machines has evolved on Earth exactly once, and that is the only kind that is of interest in Fermi's Paradox.
Furthermore, the current best guess at the evolutionary driver of kind of intelligence that makes complex machines is that it's a peacock's tail, and extravagant sexual display that had relatively little utility outside of attracting a mate or two. Therefore the whole "making complex machines" aspect of our intelligence is more-or-less an accident, not the result of direct selective pressure at all.
Men are very slightly better at some spacial reasoning than women because we hunted more, maybe, but that very slight difference is a measure of how little practical, non-sexual, selective pressure their actually was.
So based on what we know at the moment about the kind of intelligence that makes complex machines it seems likely that the resolution to Fermi's Paradox is that it is unbelievably rare. We may well be the only species to have such an intelligence in our galaxy, although even I have a hard time believing we're the only one in the universe. It could be, though.
Blasphemy is a human right. Blasphemophobia kills.
...Why are we soooo certain that we *want* to be found?...
Anybody intelligent enough to be able to travel throughout this galaxy or beyond, or even just communicate, would certainly study us for awhile. They would have learned by now that we humans are a warlike race that cannot get along with one another even on our own world. Even in our fictionalized scenarios, with imagined technology, such as Star Trek or Star Wars, there is nothing but war and death, such as the destruction of entire planets by some of our imagined technology. Human history provides an absolute guarantee, that if we would meet such an advanced civilization, we would use their technology against them and one another.
All theory is gray
The flip side of this argument is that a species comes to dominance over its own planet through competitive behavior, i.e. aggression. Just because they have superior technology doesn't make them morally superior.
As for what we have to offer? There are a plethora of movies that spell this out: natural resources, a habitable planet, an enslavable population. What do you think our own warlike, inferior race would do if, say, Mars were humanly inhabitable tomorrow? Crossing the ocean in the 1500s to settle the New World was a scary proposition, and yet the Europeans didn't let that stop them. It was precisely their ambition, competition with their neighbors, and their desire to claim the wealth of those new lands that drove them to do it, even with primitive technology.
Peaceful races may fail to contact us not because of their moral superiority, but because they lack the incentive to bother.
"Give a man fire, and he'll be warm for a day; set a man on fire, and he'll be warm for the rest of his life