FERMI WAS RIGHT: SO WHERE ARE THEY?
Via Glenn Reynolds, this piece in Technology Review on a new twist to the Fermi Paradox makes the case that there may be an incredibly small number of intelligent, space faring civilizations in the entire universe - perhaps as few as 10:
The absence of alien probes visiting the solar system places severe limits on the number of advanced civilizations that could be exploring the galaxy.
The Fermi paradox focuses on the existence of advanced civilizations elsewhere in the galaxy. If these civilizations are out there–and many analyses suggest the galaxy should be teeming with life–why haven’t we seen evidence of them?
Today Carlos Cotta and Álvaro Morales from the University of Malaga in Spain add another angle to the discussion. One consideration is the speed at which a sufficiently advanced civilization could colonize the galaxy. Various analyses suggest that using spacecraft that travel at a tenth of the speed of light, a colonization wave could take some 50 million years to sweep the galaxy. Others have calculated that it may be closer to 13 billion years, which may explain why we have yet to spot extraterrestrials.
Cotta and Morales take a different tack by studying how automated probes sent ahead of the colonization could explore the galaxy. Obviously, this could advance much faster than the colonization wave front. The scenario involves a civilization sending out eight probes, each equipped with smaller subprobes for studying the regions that the host probe visits.
This is not a new scenario. One previous calculation suggests that in about 300 millions years, those eight probes could explore just 4 percent of the galaxy. The question that Cotta and Morales ask is this: what if several advanced civilizations were exploring the galaxy at the same time? Surely, if enough advanced civilizations were exploring simultaneously, one of their probes would end up visiting the solar system. So that fact we haven’t seen one places a limit on how many civilizations can be out there.
This is not only fascinating stuff, but a lot of fun as well. Next to politics, the search for extraterrestrial intelligence has been a favorite subject of mine since childhood. It parallels my fascination with space but, due to the speculative nature of the subject matter, forces me to stretch my thinking beyond facts and embrace a world of the mind unlike no other of which I am familiar. When contemplating the unimaginable distances and time periods that are necessary to give ETI serious thought, you exercise a part of the brain that is usually dormant - at least in rational laymen with an abiding interest in science but not the aptitude to get it down by the numbers.
Fermi’s Paradox, first uttered by Enrico Fermi at a lunch with several Los Alamos scientists in 1949, takes the statistical probability that there must be other intelligent species in the universe due to sheer numbers of possible planets, and asks an obvious question: So, where are they? Why haven’t they visited us? Why is there no physical evidence of them ever having been here?
Sorry, but as reliable as eyewitness accounts have been, there is no physical evidence that we’ve ever been visited - and that includes idiotic and insulting questions regarding who built the pyramids or carved the Easter Island statues. We humans are a very clever species and hardly need aliens to help us overcome small technical problems like how to haul a 10 ton block of stone the 4 miles from the Nile River to the Valley of Kings. It is insulting to humans to ascribe our ability to overcome these obstacles to anything except our own, native intelligence.
As for other “evidence,” no reputable scientist has ever come forth with physical evidence that could withstand the scrutiny of their peers. And even eyewitness accounts cannot confirm that what they report came from another planet. In short, as a scientist, Fermi was asking a perfectly legitimate question. We have no evidence of ET’s probes, or spaceships, or any other alien artifact despite the statistics that point to a universe that should be teeming with intelligent life.
And beyond that, there is the idea that a truly advanced civilization would probably require unlimited amounts of energy and would tap every atom and erg they could possibly get out of their own sun. Freeman Dyson speculated that such a race of beings would enclose their entire sun - perhaps their entire solar system - in a sphere in order to capture every atom of power possible (”Dyson Sphere”). The sphere would so alter the radiation signature of the star that it would be detected by even our crude by contrast instruments.
(A great treatment of a Dyson Sphere in pop culture was a Star Trek Next Gen episode that featured Scotty being trapped in a transporter loop for 70 years after becoming stranded on the surface of the sphere.)
A civilization that is advanced enough might attempt to re-engineer their entire galaxy. In Carl Sagan’s book Contact, Ellie Arroway sees a black hole at the center of the Milky Way galaxy “eating” stars in copious amounts. It turns out that the aliens who brought her to this particular planet were trying to alter the mass of the galaxy to keep if from flying apart - a nice trick if you can do it. Again, statistics say there should be civilizations capable of such a feat but so far, we have been unable to detect such an obvious beacon of intelligence elsewhere.
So, where are they? This one should send chills down your spine:
Another possibility is that intelligent species beyond a certain point of technological capability will destroy other intelligence as it appears. The idea that someone, or something, is destroying intelligent life in the universe has been well explored in science fiction[35] and scientific literature.[3] A species might undertake such extermination out of expansionist motives, paranoia, or simple aggression. In 1981, cosmologist Edward Harrison argued that such behavior would be an act of prudence: an intelligent species that has overcome its own self-destructive tendencies might view any other species bent on galactic expansion as a kind of virus.[36]
This hypothesis requires at least one civilization to have arisen in the past, and the first civilization would not have faced this problem.[37] However, it could still be that Earth is alone now. Like exploration, the extermination of other civilizations might be carried out with self-replicating spacecraft. Under such a scenario,[35] even if a civilization that created such machines were to disappear, the probes could outlive their creators, destroying civilizations far into the future.
If true, this argument reduces the number of visible civilizations in two ways - by destroying some civilizations, and forcing all others to remain quiet, under fear of discovery. (see They choose not to interact with us) as we have seen no signs of them.
So are we being incredibly stupid in sending out signals into the void announcing our presence as an intelligent species? Some scientists have actually advanced that argument and indeed, common sense caution might be the better part of valor in this case. I can just imagine these thousands, perhaps millions of civilizations out there who are cowering in fear of some Borg-like race of bloodthirsty aliens. Very kewl. But not likely.
What is much more likely is that Einstein is right, that light speed cannot be exceeded, and that intelligent species are reduced to building multi-generational ships if they wish to explore. The biggest problem with that idea is one of technological development on the home planet outrunning the technology that built the ship originally.
Suppose we built a ship that could travel at one tenth the speed of light. We send them off to Barnards Star 10 light years away, a trip that theoretically would take 100 years (relativistic effects on time don’t become obvious unless you are traveling above 90% the speed of light).
But let’s say 10 years after the ship leaves earth, we build a vehicle that can travel at 1/5 the speed of light (2/10ths). That ship would pass the first ship in about 40 years, in which case you have expended an enormous amount of effort to build the first ship basically for nothing.
Much more likely is the probe idea outlined in the article linked above. It would take much less effort to deploy probes to search the galaxy for that “needle in a haystack.” Even given the time frame allowed - 50 million years or more - a truly advanced civilization would no doubt have overcome many mundane problems that we deal with like ecological disasters, or perhaps even death itself.
Time is an artificial construct anyway. To beings so advanced, it may even be meaningless.
The probability is, we can’t detect the aliens because we don’t even know what we’re supposed to be looking for. And the thing that always bothers me about pop culture treatment of ET is that just because the probability of life on other planets is fairly good (we may even find life in our own solar system before too long), it doesn’t necessarily follow that intelligent life - self aware, cognizant abilities, etc.) would arise.
There is even a question as to whether complex life forms beyond viruses and bacteria could ever develop elsewhere except in extremely rare cases. But intelligence itself is not where evolution on any planet would be required to end up. That’s because intelligence is simply one of a million adaptations made by living creatures, no more surprising or necessary than a giraffe’s long neck or a cheetah’s speed. It eventually made us into a super-predator, but that was only after millions of years.
So despite what the statistics tell us about life elsewhere, the Fermi Paradox might indeed apply. At any given time in the existence of the universe, perhaps no more than a handful of intelligent beings exist who have the industrial know how, engineering skills, and scientific knowledge to leave their home planet and go exploring. It certainly would answer the question “Where are they,” although it will never put the issue to rest as long as we continue to reach for the stars ourselves.
Before ET visitations are dismissed outright see Edgar Mitchell, Gordon Cooper, and Buzz Aldrin and their experiences with UFOs.
Granted there is no hard evidence. Yet some really smart people, including dozens if not hundreds of pilots have seen something that can’t be explained as normal occurances.
Just sayin’.
You are correct and I am not saying those people didn’t see something. But there is absolutely no physical evidence that what they saw was extraterrestial. Occam’s Razor still applies as does Carl Sagan’s common sense observation that “Extraordinary claims require extraordinary proof.”
I would like to believe that we’ve been visited. But belief doesn’t cut it for scientists, nor should it. That is not the scientific method and therefore, UFO’s most remain in the realm of a scientific mystery.
Such has not been forthcoming as yet.
ed.
Comment by Increase Mather — 8/1/2009 @ 11:31 am
Rick, excellent article!! I have mentioned my opinion on this before so no need to reiterate it. But why do most people assume that because we rely on BRUTE FORCE AND MASSIVE IGNORANCE that the entire universe does as well. Perhaps there is something outside of the box (limits) we have constructed that we have not learned yet that could open up the universe for us. To make it seem no larger than the Wall Mart down the street.
Perhaps I am being abysmally stupid today but how would a race know that there is a deadly foe awaiting them? If they learned of the deadly foe then the deadly foe learned of them and would have destroyed them.
Good question. One must assume that once we achieve a certain level of technological sophistication, we will be able to detect the menace and understand it. Those poor unfortunates who detected it too late or not at all would be destroyed.
ed.
Comment by Wramblin' Wreck — 8/1/2009 @ 12:43 pm
Charles Pellegrino co-wrote a very good novel about the option that sent chills down your spine: “The Killing Star”. Good info at about it: http://en.wikipedia.org/wiki/The_Killing_Star
The rules the aliens, and we, probably should follow are:
1. THEIR SURVIVAL WILL BE MORE IMPORTANT THAN OUR SURVIVAL.
If an alien species has to choose between them and us, they won’t choose us. It is difficult to imagine a contrary case; species don’t survive by being self-sacrificing.
2. WIMPS DON’T BECOME TOP DOGS.
No species makes it to the top by being passive. The species in charge of any given planet will be highly intelligent, alert, aggressive, and ruthless when necessary.
3. THEY WILL ASSUME THAT THE FIRST TWO LAWS APPLY TO US.
Comment by tps — 8/1/2009 @ 6:26 pm
Oh and the problem with any potential threat is that we might not see it until its too late. A relativistic kill vehicle could be upon us with no warning whatsoever. A kilo of matter, just plain rock, moving at .9 the speed of light will have a yield of 130+ megatons. A few hundred of those could ruin our day.
Comment by tps — 8/1/2009 @ 6:40 pm
Well, I, and ten or so others saw an unexplained event, here on earth, in a canyon setting, about 25 years ago. This Football Field sized thing, Shining light that was not regular for aircraft, passed right over the ridge line above us. No one had a camera, Plus it only took five or six seconds to be gone. No engine sound, (common, I know what a plane or coppter sounds like) Football Field sized- rectangular. dont know what it was. Prolly not a sputnic. Ten or more uf us saw it. Dont Know.
Comment by The Modocer — 8/1/2009 @ 7:45 pm
Nice article. I also enjoy thinking about things like this.
I read something at http://news.nationalgeographic.com/news/2008/11/081105-dark-flow.html
that raises some questions about what is tugging at the universe. Pretty interesting I thought.
Comment by Brad — 8/1/2009 @ 8:14 pm
SETI…the only part of mainstream science where it is permissible to believe in intelligent design.
Comment by oneblankspace — 8/1/2009 @ 8:43 pm
TPS:
Depends what you mean by top dog. Are you sure we’re top dog on planet earth? Only by our own standards, by our own cultural standards. Ants do rather well. Bacteria and viruses do quite well.
It’s the Jack London fallacy: that it’s about wolves chasing bunnies. The fact is wolves are a charity case kept alive by h. sapiens, whereas we have a hell of a lot of rabbits.
The rabbits did a better job of surviving than did the wolves. And if I were betting the mortgage money I’d say the viruses and bacteria and insects will out-survive us. After all, as Rick points out, intelligence is not the only path or the best.
Comment by michael reynolds — 8/1/2009 @ 9:49 pm
Rick:
Very cool post. Made me want to be reading science fiction.
You have really good non-fiction writing skills. Maybe fiction, too, you don’t show that hand. Despite the fact that you and I get on each other’s nerves, if you ever want some conversation on the practicalities of getting into book writing, drop me an email.
Comment by michael reynolds — 8/1/2009 @ 9:52 pm
All your speculation is wrong. Think ‘worm holes’.
Comment by daveWI — 8/1/2009 @ 10:48 pm
Cool post indeed, but you’re overlooking several important considerations, the main one being size.
Don’t forget - until Edwin Hubble in the ’30s, the universe was thought to be what we now know is only our galaxy. It was Hubble who discovered that there were other galaxies - thousands of them, maybe tens of thousands of them, he thought.
By the time Fermi propounded his theorem, the number of observable and estimated galaxies - each with hundreds of millions of suns - was still thought to be a countable number, perhaps in the millions.
By 1970, the estimated number of galaxies was in the billions.
Then (appropriately named) came the Hubble Space Telescope. Their most recent estimate is that there are 125 billion galaxies, give or take - as many galaxies as there are stars in our galaxy.
Fermi had no idea of the size of the universe, so the usefulness of his theorem is moot.
Now, since the universe is expanding, it is for all practical considerations of this sort infinite - and the infinite number of monkeys theorem steps up. That theorem as usually stated is widely misunderstood.
To refresh memories, it used to state that if you had an infinite number of monkeys randomly typing blindly on an infinite number of typewriters in an infinite amount of time, sooner or later some monkey would quite randomly type perfectly the complete works of Shakespeare (or the Bible or any other book you can imagine). Well and good - it’s a cute illustration of what infinity means.
However…the rules of randomness and logic also apply. What infinity and the theorem suggests is this - if an infinite number of monkeys etc result in the random creation of a phenomenon once - that random phenomenon will continue to recur randomly - an infinite number of times. THAT’s what infinity means.
If the evolution of intelligent life on earth is a random accident of a large (or infinite) number of occurrences, then in infinity it is a logical necessity that such an event recurs infinitely.
This is of course part and parcel of the alternate universe theories (as opposed to parallel universe theories that derive from Heisenberg and suggest that there is an infinite number of other universes in the same space we occupy) - that in a universe so vast as to be limitless, an exact and nearly exact example of myself exists “elsewhere” (no meaning to the word) - except that in some of them I’m handsome and left-handed.
So where are the aliens? Out there in a universe so teeming with life that the numbers would stagger out pitiful human conceptions of mathematics - but out there in a universe so vast and silent that even if after developing the Star Trekkian ability to warp out at ten times the speed of light we will never find each other except by the randomest of chances.
Don’t forget that Star Trek Voyager was humming along at warp 7 much of the time - 7xthe speed of light - and it was going to take them fifty years to get back from the Delta quadrant to our own Alpha quadrant - in the same pitifully insignificant galaxy.
So they’re out there all right, maybe even with their “To Serve Man” cookbooks - but the fact that they haven’t come calling yet is simply a matter of its mathematical unlikelihood and is yet another blow to our anthropocentric perception of All That Is.
Comment by Your Brother Jim — 8/1/2009 @ 11:48 pm
Michael: Actually being like a rabbit is the way to ‘win’.
You spread as far and as fast as you can so even if they wipe out one planet they haven’t killed off the entire race. That way they know there will be others to go after them if they try it.
Its a pretty good reason to get off this planet I think. Even if you don’t believe in alien attacks there are things like comet impacts, etc. The more spread out the human race is the safer it is.
Good points from both of you. One possible explanation for the apparent dearth of intelligent civilizations may be that many of them get wiped out by rogue comets, asteroids, gamma ray bursts, black holes, or even just massive solar flares from their own sun before they develop the ability to get off their rock.
Or, they destroy themselves. This is why Drake’s equation is pretty much full of crap. You can’t quantify stupidity.
ed.
Comment by tps — 8/2/2009 @ 6:23 am
Brother Jim,
Just a small correction. Warp speed is not x times the speed of light but x3 (or x^3) times the speed of light. Therefore, Warp 7 is actually 343 times the speed of light. I don’t remember where I read the original attribution but it was used in the Original Series, TNG and DS9 for certain. I don’t know about others or movies.
Comment by Wramblin' Wreck — 8/2/2009 @ 12:35 pm
Thanks, WW! That makes the point of distance even more forceful - 50 years at 343x the speed of light - to go across part of one anonymous galaxy.
Comment by Your Brother Jim — 8/2/2009 @ 5:18 pm
in Asimov’s 3 major SF series - robots, galactic empire, and foundation - Earth was indeed unique - the only planet to develop such a diverse biosphere - at the end of foundation series, he attributed it to the tides from our moon and the fact that a normal-sized planet (non-gas giant) with such a large moon was so completely rare, and hence the only planet with strong tides - churning up the oceans and radioactivity for higher rates of mutations. Anyway, it took the opposite view - that we are exceedingly rare.
Comment by Rick — 8/3/2009 @ 9:08 am
I highly recommend that you read “Rare Earth: Why Complex Life is Uncommon in the Universe,” by Peter Ward and Donald Brownlee. Ward and Brownlee argue that the presence of intelligent life on Earth is the result of an astoundingly unlikely set of circumstances. While microbial life is probably common throughout the universe, complex metazoans may be vanishingly rare. That would explain Fermi’s paradox.
Someone else recommended that book to me after I wrote a similar post to this one last year. Or maybe it was early this year.
At any rate, even if it isn’t “vanishingly rare” it is probably rare enough that it may arise every couple of hundred million years. And then all the things that could destroy it come into play so that a fully mature species capable of space travel might have occurred only 2 or 3 times in the entire history of the universe.
Then again, an alien may be sitting right next to you right now and you’d never know it because he chooses not to have you see him. But he and his buddies in the Galactic Federation are scoping us out, seeing if we’re worthy of membership.
I would not be surprised at either scenario.
ed.
Comment by Jonathan — 8/3/2009 @ 3:24 pm