Let me draw your attention to two interesting stories this morning, one harking back to the night in August of 1977 when the Big Ear radio telescope at Ohio State University recorded the famous ‘Wow!’ signal. For those unfamiliar with it, the ‘Wow!’ signal gets its name from Big Ear volunteer Jerry Ehman’s annotation (several days later) on the signal’s printout. ‘Wow!’ seemed appropriate for a signal that was 30 times stronger in volume than the background noise and took up a single 10 kilohertz-wide band on the receiver, an enigmatic 70-second narrow-band burst at almost precisely 1420 megahertz, the emission frequency of hydrogen.
A message from an extraterrestrial civilization? ‘Wow!’ seemed to fit the bill, but it disappeared and despite more than 50 repeated searches by the Big Ear team, it never recurred. In this article for The Planetary Society, Amir Alexander calls the signal “…the single most intriguing result ever produced by the Search for Extraterrestrial Intelligence,” one made all the more frustrating because of the lack of any follow-up signal. Alexander’s story alerted me to the fact that Bob Gray, a data analyst with a passion for radio astronomy, has just published a book on the ‘Wow!’ signal based on three decades of study and observation using a wide variety of equipment.
Image: A 70-second burst that came to be known as the ‘Wow!’ signal. Credit: Columbus Dispatch.
The Elusive Wow: Searching for Extraterrestrial Intelligence (Chicago: Palmer Square Press, 2011) caught my eye not only because of ‘Wow!’ but also because of my love of travel books — Gray’s journeys in support of his SETI research have been globe-spanning. Having built a radio telescope of his own using a 12-foot dish and a steerable mount from a World War II radar installation, he began by operating his own SETI program for fifteen years, looking at the region of the spectrum and the specific coordinates where ‘Wow!’ had first appeared. Then he started expanding the hunt, traveling to the Oak Ridge Observatory near Harvard, Massachusetts.
Alexander’s article tells the tale and I won’t do anything more than hit the highlights here, but suffice it to say that Gray worked with Paul Horowitz at the observatory using a 25-meter radio telescope running META (Million Channel Extraterrestrial Array). He later went to the Very Large Array in New Mexico, whose 27 dishes mounted on rails were put at his disposal for a four hour stretch in September of 1995 (this followed a lengthy proposal submission process). Still later, he wound up in Tasmania at the Mount Pleasant Observatory, working with Simon Ellingsen.
The result: No trace of the ‘Wow!’ signal despite the presence of unknown (and presumably natural) radio sources close to where it had originated. ‘Wow!’ remains a mystery and Gray’s book will keep its tantalizing story alive as he continues his personal quest to nail it down. Alexander quotes him as calling ‘Wow!’ ” “…a pretty strong tug on the cosmic fishing line,” about as charming an image as can be imagined for this most intriguing of all SETI results to date. Gray’s book is in my reading stack and I’ll be offering my own review in the near future.
Money and Commitment at the ATA
The 42 radio telescopes of the Allen Telescope Array, located near Lassen Peak in Hat Creek, California, are one day to be joined by more than 300 more if the original plan is followed, but at the moment the installation’s financial problems are what occupies its supporters even as they continue their observations. New York Times science writer Dennis Overbye tells the tale in a late January story that looks at the ATA and its possibilities, examining what he calls “…a dream deferred by politics, a lack of money and the technological challenges of searching what astronomers call ‘the cosmic haystack’: 100 billion stars in the galaxy and 9 billion narrow-band radio channels on which aliens, if they exist, might be trying to hail us.”
Image: The Allen Telescope Array continues its work as funding issues are temporarily resolved. Credit: ATA.
Centauri Dreams readers will recall that the University of California’s own funding for the ATA ran out last spring, sending the telescopes into forced hibernation until a funding appeal sent out over the SETI Institute’s Web site brought in enough money to fund about two more months of operations. The US Air Force is also interested in the array’s possibilities in terms of tracking satellites and space debris, an agreement that is still being negotiated. The ATA is back in business (since December), but the financial shortfalls ahead are sizable for an installation that needs $1.5 million per year for operations and another $1 million for the staff of astronomers.
Microsoft founder Paul Allen ponied up $25 million to launch the original project, which would be owned by the University of California at Berkeley as well as the SETI Institute, but fleshing out the remaining 300 or so antennas will require a cool $55 million, making the ATA a site in search of philanthropists. As Overbye recounts, SETI has never been robustly funded and has been controversial from the start, particularly with alarming price estimates like the $10 billion a 1971 NASA workshop came up with for a giant telescope array that would have been called Cyclops. The infamous 1978 ‘Golden Fleece’ award from Wisconsin senator William Proxmire only added to the problems, leading to the cancellation (in 1993) of NASA’s SETI survey work.
Taking SETI private was the only option, but the tough-minded scientists who continue this work soldier on despite the challenges. Writes Overbye:
Astronomers now know that the galaxy is teeming with at least as many planets — the presumed sites of life — as stars. Advanced life and technology might be rare in the cosmos, said Geoffrey W. Marcy, the Watson and Marilyn Alberts in the Search for Extraterrestrial Intelligence professor at the University of California, Berkeley, “but surely they are out there, because the number of Earthlike planets in the Milky Way galaxy is simply too great.”
A simple “howdy,” a squeal or squawk, or an incomprehensible stream of numbers captured by one of the antennas here at the University of California’s Hat Creek Radio Observatory would be enough to end our cosmic loneliness and change history, not to mention science. It would answer one of the most profound questions humans ask: Are we alone in the universe?
I like the way Overbye frames this story, highlighting a band of astronomers depending on “…the stubborn strength of their own dreams,” a description which goes a long way toward explaining Bob Gray’s own persistent hunt for the ‘Wow!’ signal as well. It takes passion, and a hide as tough as a Texas longhorn’s, to fight through budget shortfalls, political maneuvering and the sheer intractability of the technical problems involved in pulling an intelligent signal out of the cosmos. But things are happening again at Hat Creek and have been since December, while the question of how long the site will stay operational hovers over SETI like an ominous cloud.
@Alex:
Then what are we? A fluke? Special, somehow? Or doomed to become a low tech, planet bound civilization ourselves?
“Well, yes, but life formed spontaneously, while self-replicating machines will be designed. ”
That is an assumption, a belief, not a scientific statement.
I am treating it like a fact. You are welcome to propose an alternative that makes sense.
Bob (February 6, 2012 at 19:55)
Eniac:
“Well, yes, but life formed spontaneously, while self-replicating machines will be designed. ”
That is an assumption, a belief, not a scientific statement.
On the contrary, the first part, about life’s origin, is a very scientific statement, for which there are many direct and indirect scientific indications.
Your counter-statement is unscientific and reminiscent of creationism and the creationist way of argumentation, who call any scientific theory that does not fit in with their own views, ‘just an opinion’, ‘a matter of viewpoint’, ‘just a theory’, etc.
(The second part, about machines, is self-evident).
spaceman:
“The existence of mere ingredients sheds no new light on how they would come together in the prebiotic Earth to produce the first living cells no more than the existence of silicon explains the existence of laptop computers.”
Emphatically no, wrong (with all due respect for the rest of your argumentation): this is a typical creationist faulty argument (mind: I am not at all implying creationist sympathies here!, just the line of argumentation):
the former depends on natural processes, organic- and biochemistry, whereas the latter is clearly and inevitably inorganic, artificial, and will always be.
@henk’s reprint of RK’s article;
apart from the fact that it is absurdly arrogant in tone, and despite the fact that I myself am extremely cautious with regard to ETI, I was surprised by its naivety, it shows again that people often make the bluntest assertions with the greatest brawl but without evidence:
The entire argument hinges on a few very (VERY) weak assumptions, presented as facts, namely (apart from the discussion ‘does life always lead to intelligence’):
– intelligence leads to technology and civilization.
– technology and civilization lead to interstellar capabilities.
– an (interstellar) spacefaring civilization will always colonize the entire MW galaxy within a 100 thousand years (in fact, this is ridiculously fast even by the most optimistic estimates).
– a galactic civilization will always cross over to other galaxies to coloniza those as well.
Clearly very feeble assumptions, not facts.
The last paragraph made me laugh, it largely refutes the previous argumentation: if chances for ETI are that good, even with all the foregoing negativism, it’s definitely woth a search!
A lot of serious scientific research, and every major lottery-prize, are based on smaller chances :-)
Further I agree with ljk: we’ve hardly begun scratching the cosmic surface and are already making all sorts of claims and assertions concerning life and intelligence in the universe that verge on religious zeal.
We are like a native on his remote Pacific island claiming that he is all alone, simply because no one has answered to his shouting in the dark (and besides, there can be no other inhabitable place in the vast ocean than his own island).
Let’s first do a complete spectro-analysis of all planets of the nearby MW galaxy (say up to a few hundred light years, a couple of hundred thousand stars) for biosignatures, before even daring to make such absolute and ridiculous claims.
Eniac said on February 6, 2012 at 17:14:
[Quoting LJK]: I get the strong feeling that a lot of this pull towards the side of a Cosmos devoid of any life beyond Earth is a wistful harking back to the simpler days when most everyone (except for a handful of annoying ancient Greek and Medieval natural philosophers) considered humanity and our planet (or should I say the big flat disk of dirt surrounded by water with a big dome overhead with pinpricks of light visible at night when the Sun actually set that were holes in the sky where Heaven was shining through) to be the Focus of Everything and God(s).
“And I get the feeling I hear wistful harking back to the simpler days when most everyone thought there were people on the moon and canals on Mars. Until, that is, improved telescopes and space probes drove them away and they became aliens from other stars riding around in cloaked flying saucers and being kept prisoner in the New Mexico desert.”
LJK replies:
The days of the Martian Canals were indeed a scientifically romantic and exciting time, when it seemed we were on the verge of finding ETI, ones right next door cosmically speaking, no less. Misguided as it all ultimately was, they certainly got a lot of people thinking about astronomy, alien life, and humanity’s place in the Universe. We can even thank (or not) the canals and their proponents for bringing about the idea and numerous stories of aliens invading Earth for our resources, etc., via H. G. Wells novel The War of the Worlds.
Nevertheless, I am not “harking back” for the Martian Canals and certainly not for UFOs, though there are a few reports which are interesting and not easy to dismiss, but the mainstream scientific community will not recognize or investigate them seriously due to peer pressure and public ridicule.
This is one reason among several as to why you will find it so hard to get any solid evidence for visitations from ETI. Most UFO stories are bogus hoaxes, outright lies, and untrained people mistaking natural and human-made phenomena for alien spaceship, often while caught up in a form of mass hysteria. Nevertheless, there have been a few stories over the years which do require more proper attention, especially since SETI is slowly coming around to the idea of alien probes monitoring us from within our Sol system. They could also spread nanotech all over this planet and we would not have a clue to its existence.
If I am “harking” for anything (thanks for making me start to regret using that word, Eniac) when it comes to alien life, it is that people recognize that we have barely scratched the surface when it comes to truly searching for extraterrestrial beings of all stripes and should not declare them non-existent because they haven’t come calling. The galaxy and the Universe are much, much, MUCH bigger than Earth-bound humanity can truly appreciate, and we are not exactly standing out on a cosmic scale.
Get just a few parsecs from Sol and our sun is just another star among the 400 billion in the Milky Way. Our electromagnetic signals make a sphere just 200 light years across in a galaxy 100,000 light years wide, and most of those signals are oh so faint.
Eniac said:
[Quoting LJK] All we need to do is prove that the Wow! signal really was from an ETI and all these claims of our being alone in the Universe go out the window.
“That sounds pretty wistful to me….”
LJK replies:
Why and how exactly? It is a plain and accurate statement. If it is wistful, then a lot of people who have been investigating it for years are also wistful, including Mr. Gray who just wrote a whole book on the subject and has literally traveled the planet and beyond in search of this signal.
By the way, as I asked way back in one of the first comments in this thread, does anyone know anything more about a report of a radio detection from Australia in 1990? Apparently it was even better than the Wow! signal but I can find virtually nothing else on this event. Someone must know something about it.
Eniac said:
“I get the thing about “we haven’t looked enough” and “aliens out there might not be interested in us”. What I do not get is why all the hypothetical spacefaring aliens are so lazy or sessile that they never once in 4 billion years decided to come here, our perfectly usable solar system. Well before we existed, or anything else worth being put in a zoo.
“Statistically, even the most sluggish of random walks from star to star would have long since brought them here. Unless they actively avoided our system, with extraordinary efficiency. Why? Is there anything special about that soup of blue-green algae that was the Earth for most of its history? I thought we were not so special?
“RK is not the most polite person around, but in this he is right: The vastness of time trumps the vastness of space. By far. If the aliens existed, in the vastness of time they would have made their way here. If they had been here, we would be their descendants. It is not a matter of finding them, or recognizing them: it is a matter of our very existence.”
LJK replies:
In addition to such reasons for a lack of evidence as: If ETI came here eons ago their evidence might be long gone, humanity would not have recognized an alien artifact until a few centuries ago and even now may still not depending on what it is the visitors left behind, and most professional scientists would not dare risk ridicule and career loss to declare they found an alien relic even if they felt they had strong evidence for such a claim, I add these ideas to the mix:
1. You and others say that it just takes one species to spread throughout the galaxy. Well, what if there was just one ETI in the Milky Way who tried so far? Do you think one effort could actually manage it and last millions of years in the process? And again, you may think Earth is just a dandy place for a visit or stay, but would an ALIEN species think the same?
I wonder if there are some Jovian gasbags floating in the clouds of a gas giant exoworld or some smart sea creatures swimming in the global ocean of some Europa-type place asking why haven’t they been visited by beings from other planets, too?
2. I was just reading a fascinating paper on how Westerners tend to view robots and AI compared to the Japanese. Even though we are both of the same species from the same planet, our cultural viewpoints differ in important ways: Westerners tend to see capable machines (and by extrapolation ETI) as potential threats to our way of life, while the Japanese embrace them as kindred spirits and see machines as a vital part of their society.
I bring this up because if members of the same intelligent species can have such significant differences of opinion on a similar subject, perhaps the same goes for colonization. We think spreading ourselves to new worlds is the way to go, and it probably is for our species and certainly our culture, but aliens may not or may literally think exploring their inner selves is the way to go. And see above for my comments on why just one ETI that does want to colonize the galaxy may not be enough to attain such a goal.
Now, to grab from Eniac’s comment to Alex:
Eniac said on February 6, 2012 at 17:20:
@Alex:
The essay is still a rehash of the Drake equation. Conflating intelligent civilizations arising with colonizing the galaxy is also a huge assumption. The galaxy might be littered with low tech, planet bound civilizations, and therefore be silent.
“Then what are we? A fluke? Special, somehow? Or doomed to become a low tech, planet bound civilization ourselves?”
LJK replies:
Why not a combination all three? Or something else entirely that we have not yet thought of? There is more than one answer to the question of alien life.
Here’s another less than optimistic wiev of a mecanism that might be capable of preventing a toolmaking species from getting of its planet :
The Breeding Frenzy !
By inventing contraceptives , it SEEMS that humans have managed to free themselves from one of the more destructive parts of their own nature .
Cheating nature is a dangerous thing to do though , because the mecanisms involved are parts of anybodys and everybodys consiousnes , and therefore impossible to perchieve objectively . The human breeding-fenzy is far from over , actually it might right now be in the proces of finding a way around the obstacle of contraceptives . Any religion or ideology which preach a moral -religious-etnic demand for breeding frenzy , might eventualy get to be a dominant majority in a former well functioning “sane” society .
Take walk around the slums of London or Paris…
Another more long range possiblity is that evolution have an effective backup plan in case sexual atraction should somehow fail (by being Cheated) :
If a population i selected over many generations for the tendency to have lots of babies ,in spite of contraceptives being avaible , it might be the case that humans could develop a GIGANTIC nesting-instinkt of the kind that we have so far only seen after major wars …and Voila! the breeding frenzy can go on , and so all the planets raw materials will be consumed and or destroyed in a combustion-like exponential growth , which would leave no chance for ever acumulating the critical surpluss needed to achieve starflight.
I was interested in the replies to Bobs comment of 6 Feb because it address the heart of science. As I expected none commented on how mysterious science really is, after all it is irrational to a priori believe that EVERY phenomena in this universe has rational explanation. It is wishful to an absurd degree to believe that the rules of this universe would be simple enough to be comprehensible to the human mind.
I will admit it even if no one else will. When Einstein said “The most incomprehensible thing about the world is that it is comprehensible” he was right. There is no explaination!
Ronald, why would Earths contemporary SETI be trying to contact non-technological ETI. Surely it makes more sense to restrict the argument to those groups we could contact, whereupon the conclusion is that it is delusional to look outside Sol.
@Ronald:
Sorry, Ronald, I think you got these wrong. These are the assumptions that are actually needed:
– intelligence MAY lead to technology and civilization. [This is a proven fact]
– technology and civilization MAY lead to interstellar capabilities. [We certainly think so]
– an (interstellar) spacefaring civilization will [always]SOMETIMES colonize the entire MW galaxy within [a 100 thousand years] MUCH LESS THAN A BILLION YEARS (in fact, this is ridiculously fast even by the most optimistic estimates [you are right in this comment]). [To me, this is obvious]
– a galactic civilization [will always] MAY EVENTUALLY cross over to other galaxies to coloniza those as well. [This last one is really not necessary and a little bit beside the point]
@LJK:
You have not understood the argument. Any lifeform that can and sometimes does colonize other systems WILL eventually fill the galaxy. Not because of some “effort” that “lasts millions of years”. The only thing that would need to last that long (billions, actually) is an effort NOT to spread, or to avoid certain locations. Spreading is natural, it happens in small, momentary episodes, whenever lifeforms on one system decide to send a seed to a neighboring system. No grand plan, or million year effort is needed. Just as bacteria growing in a Petri dish have no plan, no long lasting “effort”, just a propensity to keep dividing as long as there is food and space.
Your argument that ALL aliens will somehow FOREVER avoid settling our solar system is hard to swallow. It would require our system to be very special in some way. This is against the Copernican principle, and also contradicted by the accumulating evidence that ours is fairly ordinary as stellar systems go.
@Rob Henry
The Einstein quote is need very poignant, as is your statement about the pursuit and assumptions of science.
I’d like to add a thought, primarily that we are part of this universe and therefore party to its rules. Should we not therefore try to determine what they are?
While I’m at it, here are a few more thoughts:
1. There is an evolutionary advantage to the pursuit of science.
Understanding the physical nature of the locale give a species an advantage
over others that do not.
2. What is maybe more surprisingly, at least to me, is why more people do
not pursue science. The fraction that actually does is vanishingly small.
3. Societies have to in the long run move towards a more technocracy based
existence as most problem will increasingly require very sophisticated
solutions.
@Rob Henry, February 7, 2012 at 16:01;
“Ronald, why would Earths contemporary SETI be trying to contact non-technological ETI. Surely it makes more sense to restrict the argument to those groups we could contact, whereupon the conclusion is that it is delusional to look outside Sol”
I presume you are responding to my comment to henk’s reprint of RK’s article (Ronald February 7, 2012 at 10:56).
Well, simple answer: I was not at all suggesting that “SETI be trying to contact non-technological ETI”, logically it could/would/should not.
I was rebutting RK’s suggestion that (intelligent) aliens do not exist at all, based on his own weak argumentation.
One simply cannot make such an absolute claim, and certainly not based on those very shaky arguments.
And yes, I think we should definitely be looking for signs of life outside our solar system, even make it a scientific priority, but first and foremost not SETI but spectro-analysis of (terrestrial) planet atmospheres for biosignatures.
With the first two, you are giving up the Copernican principle, the only thing (apart from wishful thinking) compelling you to postulate the existence of ETI in the first place. With the third, you are giving up the chance that we will ever meet any ETI. Either way is not what you seem to be looking for.
Something else? Logically, there is not much room between being special and doomed to stay local. If neither is true, some ETI should have spread by now.
I suppose it is possible that interstellar colonization does not happen, for whatever reason, and that the universe is full of locally confined ETI communicating by some means we have not yet discovered. That would be the SETI researcher’s dream, and it is somewhat plausible, except for that missing reason.
The astrobiologist’s dream would be that technology is a fluke, for some reason. Again, somewhat plausible, except for that missing reason.
Not being either a SETI researcher nor an astrobiologist, my bet is on abiogenesis being the fluke, it having the most reason, in my eyes.
Rob Henry said on February 7, 2012 at 15:49:
“I was interested in the replies to Bobs comment of 6 Feb because it address the heart of science. As I expected none commented on how mysterious science really is, after all it is irrational to a priori believe that EVERY phenomena in this universe has rational explanation. It is wishful to an absurd degree to believe that the rules of this universe would be simple enough to be comprehensible to the human mind.
“I will admit it even if no one else will. When Einstein said “The most incomprehensible thing about the world is that it is comprehensible” he was right. There is no explaination!”
LJK replies:
Rob, whoever told you that science says it has all the answers not only does not understand science but is also deluding themselves as well as you.
Of course science does not have all the answers and it is constantly reworking itself as it makes new discoveries. However, as much as I am often disappointed with human behavior and limitations, we obviously do know some factual things about the Universe, otherwise we would be unable to understand it or function in it at all. Certainly we understand some fundamentals such as quantum physics which were virtually unknown not all that long ago.
Science is not perfect and probably never will be, but when it is used properly and objectively it is one of our best tools to learn about the true nature of the Cosmos. Maybe there is something better out there but so far science has done a lot of good for our awareness and improved many aspects of our society such as learning the true nature of diseases and how to combat them. Want to go back to the eras before vaccinations and public sanitation? Didn’t think so.
Here, you will like reading about this guy:
http://philosophyofscienceportal.blogspot.com/2012/02/misplaced-assumptions.html
Eniac February 7, 2012 at 23:25;
I think you are mistaken or we are not understanding each other well.
Particularly with regard to the first two, where you write MAY, I had, in retrospect, actually even wanted to write WILL ALWAYS.
Rationale is reason of logic: if you are right and RK just meant MAY, SOMETIMES, and hence intelligence MAY or MAY NOT lead to civilization, technology and interstellar travel and colonization, then there is no real Fermi paradox and no question necessary concerning ‘where are they?’. Then it is even more unsubstantiated to state ‘there are no aliens’.
No, RK’s point is that an intelligence will inevitably “rise and colonize the entire galaxy”.
But in fact it gets even worse, RK makes himself quite suspect by bluntly stating that it takes only 100,000 years to colonize at least half of the MW galaxy, because (here it comes): “the galaxy is 100,000 light-years in diameter and civilization arose on Earth a mere 10,000 years ago. Even under the most pessimistic assumptions, within 100,000 years of its rise, an intelligent technological species will have colonized half of the galaxy”.
This is simply astounding in its fallacy and bone headedness!
And I just found another bold assumption: an intelligence will always “colonize the planet and use it productively” (instead of preserving it).
In fact, the whole article is so wrought with unfounded assumption, false (circular) reasoning and false logic, that it hardly deserves attention. It reminds me of a recent article by a philosopher, who asserted that god must exist, because 1) we cannot say with certainty that he does not exist (reasonable), and 2) if it is impossible to know for sure if a statement is true, then that statement is untrue, hence god must exist. Clearly a logical fallacy.
Whose ossified brain, Mr. RK?
Eniac February 8, 2012 at 9:36:
“my bet is on abiogenesis being the fluke, it having the most reason, in my eyes”.
Although I often agree with you, here you go even further than RK, (again) equating (any biological) life to intelligence, etc.
As you may know by now, I strongly disagree with that viewpoint for scientific (biological) reasons, but remarkably we still probably agree on the outcome: intelligence (and civilization, technology, etc.) are simply vanishingly rare, with a good chance of us being the only ones in the MW at present.
Where your way of reasoning (abiogenesis and hence life are flukes) and my viewpoint (primitive life is common, higher life uncommon, intelligence etc. extremely rare) differ in consequence is that if I am right, we will eventually find lots of planets with life (by means of spectroanalysis, biosignatures), but SETI would still be fruitless.
I also add, that my viewpoint would still be compliant with the Copernican and cosmological principles and at the same time, yes, we would be ‘special’ as an intelligence, although I prefer the phrase ‘extremely rare’.
Rarity is not against mentioned principles, working about the same way spatially (we being the first intelligence in the MW galaxy) as temporally (we being the first intelligence in the history of the earth).
A smart observer (like Eniac) may now note that I seem to contradict my previous criticisms against the RK article, in which I stated that one cannot assert that we are the only intelligence *on the basis of RK’s arguments*. However, I was merely rebutting RK’s argumentation and absoluteness.
I do agree with Eniac’s standpoint of extreme rarity (to the point of uniqueness ?) of intelligence, but just not with equating that to life in general.
Eniac, I apologize if I have given you the impression that I do not think anyone has ever even attempted to colonize the Milky Way galaxy or any other galaxy. I agree that the effort has probably been made at least a few times, assuming there is intelligent extraterrestrial life of course.
What I do question is whether these intrepid ETI would want or need to colonize every single solar system in the galaxy. This includes our Sol system and Earth. As I have said before, I find it very doubtful that there is another world out there so similar to ours that an organic alien being could just step out on our soil unprotected without any physical issues. I can see an ETI stopping by to check us out and resupply in our planetoid and comet belts, but this presumes the beings in question are organic and operating on some version of the Worldship we got all excited about a few months ago.
I will in fact go you one better than your persistent question about the lack of obvious evidence for aliens in our celestial backyard and ask why haven’t we seen evidence for other solar systems taken apart and reassembled in an orderly fashion? So far every alien star system we have come across appears to be untouched at the very least by advanced ETI capable of making the natural resources into something more efficient for their perceived purposes. I know one can argue that we have barely begun to find the many billions of solar systems that probably inhabit the Milky Way, but the scale I am talking about should be much more noticeable than even a super Jovian planet.
To be honest, the more I think about a group of organic beings in some big ol’ starship colonizing every planet in the galaxy, the more I think it is a concept that is in need of updating just like current SETI methods and a serious reevaluation as to what kind of intelligent beings would be the best-suited type to utilize the galaxy. The answer I keep coming back to is the artificial kind of the type that thinks and acts on very large scales in terms of space and time, where interstellar colonization of the type most people consider is irrelevant to them.
Another plausible scenario for the perceived absence of ETI is the one put forth in Robert J. Sawyer’s SF novel from 2000 titled Calculating God: Technological species which invent virtual reality abandon the external world to spend their days in paradisiacal settings of their own making. In the novel, the ones who go VR go so far as to hide the evidence of their past and present physical existence from any outsiders to remain undisturbed indefinitely. If such sophisticated VR were available to humanity now, it is a sure bet that many people would opt out of “real” life to dwell in an artificial fantasy world forever.
Just to add some final points: If aliens did ever come to Earth, the odds are it happened a long time ago and if they did leave any evidence, it could be destroyed or deeply buried. Oh heck, it might be staring us in the face right now and nobody recognizes the artifact for what it is. This leads to my second point, that an advanced ETI could be here and monitoring us right now and it wouldn’t take much to avoid being detected by us.
Eniac – To add: I also disagree with the SETI folks who do not think anyone ever bothers to attempt interstellar travel or that it is somehow impossible. That attitude may be changing a bit, but I distinctly recall during a SETI lecture I attended at Harvard in 2000 how a group of SETI professionals started off the talk (it was a panel discussion) by displaying one hand-drawn rendition of a starship concept on the overhead projector screen (this was before Power Point – shocking!) that looked like something out of Star Trek. This means it was very complicated and probably something that would not be built by humanity for a very long time, if ever.
The panel threw in how much such a starship would cost to build (Answer: Ridiculous amounts of money and resources) and how much energy it would require to operate properly (Answer: More than our whole civilization would use in thousands of years) and summarily dismissed the idea that anyone would ever build such a thing.
Of course mainstream SETI used similar thinking to dismiss Optical SETI for decades until the late 1990s, claiming that this method of communication was just too sophisticated for us to handle, even though we could a laser transmission easier than digging through millions of radio frequencies and hoping to find the one artificial one amongst all the natural radio noise of the Universe.
For the record, I tried arguing in the Q&A that one did not need a big fast ship with a complex star drive to cruise the galaxy, but it became quite clear that the panel was not interested in discussion interstellar vessels, period. As I said, I think and hope we have gotten just a bit more open-minded and sophisticated since that distant, primitive year of 2000 A.D. when it comes to SETI and starships.
“I attended at Harvard in 2000 how a group of SETI professionals started off the talk (it was a panel discussion) by displaying one hand-drawn rendition of a starship concept on the overhead projector screen (this was before Power Point – shocking!)”
Tsk! I first used PP in the 80’s, from before the company was purchased by the evil ones. Sad to say, I still use it, though not to draw pictures of starships.
No, Ronald, it is not necessary that EVERY intelligent race colonize the galaxy. One is sufficient. Thus the “may” or “sometimes” instead of “always”. You only get out of the Fermi conundrum if you postulate “never”, which is a worse assumption than “sometimes”.
Equate life to intelligence? I would never do such a thing. However, obviously there can be no intelligence without life. While there can be life without intelligence, I consider it unlikely that intelligence will not eventually develop, given enough time. We have seen it happen, in plain view of paleontologists, and there is no clear bottleneck that we could point a finger to and say: This here was a fluke, it will never happen anywhere else.
There must be some bottleneck, though, somewhere between a habitable planet and a galaxy colonizing race. Otherwise, the solar system would have been settled long before our ancestors crawled out of the sea. Abiogenesis is where I point my finger, you may chose a different point. What we know for sure is there are no galaxy-colonizing ETI. All of the steps before that are fair game. I dislike all those coming after our present, because they spell doom for our interstellar ambitions. I dislike those between abiogenesis and technology because they discount the amazing ability of life to develop and fill every available niche. We now know that the bottleneck is not a lack of habitable planets. That really leaves abiogenesis as the most acceptable option. By process of elimination, if nothing else.
@Ronald: I see that our viewpoints appear to have converged to almost perfect agreement, without me noticing until now…. :-)
Except for the microbial life is common, thing, of course. :-))
@LJK:
If you do, you will have to come up with a plausible scenario of how the expansion would be stopped. Every daughter colony will, in time, develop into its own world, independent of the mother world. Much more independent than, say, the American colonies, because of the greater difficulty in travel and communications.
To me, it is far from obvious what mechanism would cause ALL the daughter colonies to refrain FOREVER from colonizing the next available star system, like their ancestors did. Can you name one?
This is a very good point. If you look over my arguments, you may see that I have tried to avoid making any assumptions about the nature of the colonizing entities. No assumptions are needed, except that they replicate, require space and resources, and are able to bridge the gaps between stars. By definition, they will be life. By necessity, they will be descendants (in the widest sense) of organic beings, but they themselves may be machines or something else entirely, without affecting the argument.
On your first point: I am not talking about visits. I am not sure if visits make sense at all, but in either case, what we are talking about are colonizers. People who will go to a new star system to live there, and have babies there (even if they are baby machines), without plans to leave. You seem to assume that all such colonies are temporary. I say: Life is never temporary. Wherever it goes, it stays. Occasional extinction events notwithstanding: those will just leave new niches to fill. It has been like that on Earth, for billions of years. Why not in the galaxy?
On your second point, I am with Nick: If your belief in the existence of ETI is based on their skill at hiding, I’ll go with elves and fairies any day.
Do Alien Civilizations Inevitably ‘Go Green’?
by Paul Scott Anderson on February 8, 2012
In the famous words of Arthur C. Clarke, “Any sufficiently advanced technology is indistinguishable from magic.” This phrase is often quoted to express the idea that an alien civilization which may be thousands or millions of years older than us would have technology so far ahead of ours that to us it would appear to be “magic.”
Now, a variation of that thought has come from Canadian science fiction writer Karl Schroeder, who posits that ”any sufficiently advanced technology is indistinguishable from nature.” The reasoning is that if a civilization manages to exist that long, it would inevitably “go green” to such an extent that it would no longer leave any detectable waste products behind. Its artificial signatures would blend in with those of the natural universe, making it much more difficult to detect them by simply searching for artificial constructs versus natural ones.
The idea has been proposed as an explanation for why we haven’t found them yet, based on the premise that such advanced societies would have visited and colonized our entire galaxy by now (known as the Fermi Paradox). The question becomes more interesting in light of the fact that astronomers now estimate that there are billions of other planets in our galaxy alone. If a civilization reaches such a “balance with nature” as a natural progression, it may mean that traditional methods of searching for them, like SETI, will ultimately fail.
Of course, it is possible, perhaps even likely, that civilizations much older than us would have advanced far beyond radio technology anyway. SETI itself is based on the assumption that some of them may still be using that technology. Another branch of SETI is searching for light pulses such as intentional beacons as opposed to radio signals.
But even other alternate searches, such as SETT (Search for Extraterrestrial Technology), may not pan out either, if this new scenario is correct. SETT looks for things like the spectral signature of nuclear fission waste being dumped into a star, or leaking tritium from alien fusion powerplants.
Full article here:
http://www.universetoday.com/93449/do-alien-civilizations-inevitably-go-green/#
Eniac said on February 9, 2012 at 0:24:
“On your second point, I am with Nick: If your belief in the existence of ETI is based on their skill at hiding, I’ll go with elves and fairies any day.”
How hard would it be for an ETI in the Sol system to hide from us? It wouldn’t take magic. Just plant yourself on the lunar farside or stay out in the Planetoid Belt. And if they use nanotech or something even more sophisticated as sensors to track our activities, which is an actual technology and makes sense for an advanced species, they could be just about anywhere on Earth and no one would detect them, let alone bother to look for them.
Just like a zoologist studying the natural habits of creatures on Earth, if the ETI want to examine us as we truly behave and function, they are not going to want to make themselves obvious, even if most people are at least aware of the concept of alien life.
I just don’t quite get why you think an ETI wanting to be unobserved by a less advanced species like us is somehow ridiculous?
And see the article I just posted in this thread on the possibility for advanced ETI to “go green”. I actually don’t have such a problem with aliens coming to the Sol system as you think, I just don’t think they would necessarily leave the equivalent of Kilroy Was Here all over the place for numerous reasons.
Eniac said on February 9, 2012 at 0:24:
[Quoting LJK] I agree that the effort has probably been made at least a few times, assuming there is intelligent extraterrestrial life of course.
“If you do, you will have to come up with a plausible scenario of how the expansion would be stopped. Every daughter colony will, in time, develop into its own world, independent of the mother world. Much more independent than, say, the American colonies, because of the greater difficulty in travel and communications.
“To me, it is far from obvious what mechanism would cause ALL the daughter colonies to refrain FOREVER from colonizing the next available star system, like their ancestors did. Can you name one?”
LJK replies:
It would be darkly ironic but in keeping with the nature of the Universe that some ETI did establish intertstellar colonies, including on Earth, in the past but it was one of the few from that species that somehow got wiped out and then had all traces disappear, such as under a lava flow or washed out to sea by a flood.
Between my logical assumption that no mortal species is perfect and impervious and the unpredictable actions of nature, there should be at least a few instances given the odds of multiple colonization efforts that a certain fraction of colonies will fail. Earth could have been one of those failures in light of the lack of obvious evidence for ETI.
Though I still say even if an ETI were inclined to act like us on some kind of galactic version of Manifest Destiny that they might not exactly act as we would or leave remains in the same manner, if at all. Plus see again my arguments about nature removing their artifacts and/or current humans ignoring or hiding such evidence out of ignorance or fear of ridicule.
And I am actually much more intrigued in wanting to know why we don’t see alien solar systems or even other galaxies obviously reshaped by a high intelligence. Now why is that when we live in a galaxy ten billion years old with at least one estimate that some Earthlike planets might be 1.8 billion years older than ours on average?
Eniac, have you seen some of those recent television programs and books about what would happen to our civilization if humanity suddenly disappeared and we left all our artifacts to the whims of Earth?
See here, for example:
http://www.history.com/shows/life-after-people
The answer is that most of our current cities and other artificial objects would disappear in a matter of centuries, buried and decaying under thick forest growth or sheets of ice depending on the era. Ironically, cell phones would remain intact for thousands of years, but even the Great Pyramids of Egypt would become piles of dust in about 125,000 years.
The only human artifacts that will last for many millions of years are the ones we left on the Moon and in deep space. The two Voyager Interstellar Records are conservatively estimated to survive intact over one billion years if left undiscovered in interstellar space.
So if a colonizing ETI ever did establish a base on Earth, our planet has likely either long ago destroyed it or swallowed it up somewhere deep. Now try to get some professional archaeologists to go searching for it.
Here is the point you are missing in plain sight: Why would humanity suddenly disappear? It would not. I thought I had made this abundantly clear: We are not missing perishable artifacts. We are missing the living descendents.
But wouldn’t it just be a matter of time until ETI showed up again to settle that newly empty system?
I did not mean to say it would be difficult. I just meant to say that skill at hiding is such a versatile justification for the existence of anything that it works for elves and fairies as well. In other words, I don’t find it convincing.
http://www.messagetoeagle.com/mystsignals.php
Mysterious Signal From Outer Space
Is Someone Trying To Contact Us?
30 January, 2012
MessageToEagle.com – A mysterious signal coming from a region of space between the constellations Pisces and Aries has been picked up on three different occasions by the Arecibo radio telescope in Puerto Rico.
The signal is very puzzling and does not resemble any known astronomical phenomenon. Researchers who have studied its frequency pattern do not believe it is natural interference or noise.
Was the signal transmitted deliberately by an extraterrestrial civilization on a distant planet? Scientists remain cautious but we cannot dismiss the possibility.
Astronomers believe there are about 10,000 intelligent civilizations in our galaxy alone.
Lets not forget that there are hundreds of billions of galaxies in the Universe, which means the Universe may actually be teeming with life.
Some years ago, in 2008, astronomers announced they picked up a mysterious signal from outer space. It was not the last time they heard the mysterious sound.
SETI and other astronomers were excited about the news, but they were also worried the signal may never be completely decoded.
“We probably won’t be able to decode it. We’ll know something’s out there, but we won’t know much about their civilization, ” said Dan Wertheimer of the UC Berkeley SETI Project.
SHGb02+14a, as the signal has been named has been heard on three occasions adding up to about a minute. This is not long enough firmly to establish its source, but its frequency of 1420 megahertz has interested scientists, as it is a main frequency at which hydrogen, the most common element in the Universe, absorbs and emits energy.
Scientists have various opinions about the nature of SHGb02+14a.
Eric Korpela of Berkeley, who has analyzed the signal, said: “We are looking for something that screams out artificial. This doesn’t, but it could be because it is distant.”
Dr. Korpela point out that the interference with the Arecibo telescope could also make the signal look like it is always coming from the same point. “Perhaps there is an object on the ground near the telescope emitting at about this frequency.”
David Anderson, director of Seti@home, said: “It is unlikely to be real, but we will definitely be re- observing it.”
Jocelyn Bell Burnell, of the University of Bath, said that the signal could be a previously unknown astronomical phenomenon, such as a pulsar she detected in 1967. “It may be a natural phenomenon of a previously undreamt-of kind like I stumbled over,” she said.
Woodruff Sullivan, of the University of Washington in Seattle, said the research suggests that a message from an advanced alien civilization could already be lurking undetected in the solar system.
“This scenario is reminiscent of Arthur C. Clarke’s 2001: A Space Odyssey, in which a monolith discovered on the Moon has been left by extra-terrestrials. If archaeologists were to find such an object, it would hardly be the first time that science fiction had become science fact,” said Sullivan
Of course, even if astronomers somehow manage to decode the signal, they will face another problem – What should we reply to an alien civilization? How can we communicate with these beings?
We still don’t know if someone has been trying to contact us, but the signal coming from a galaxy very away remains intriguing and we hope we may one day find out whether it is of artificial origin or an unknown natural phenomenon.
Finally, the answer to the Fermi Paradox: the shy green entities have visited us after all:
“These are messages I have gathered over several years, from fairies, elves, gnomes, sprites and other nature spirits. Though often shy with humans, many of them are eager to work with us to heal the damage we have done to nature. If we are patient and open-hearted, we can sometimes catch a glimpse of them in our gardens and especially in the wilderness.”
http://fairysource.com/fae.html
Eniac, yes quite reassuring that we largely agree on most points, just before the weekend :-)
Except still for one thing, but maybe we mean the same thing in a different way, reasoning alongside eachother:
“No, Ronald, it is not necessary that EVERY intelligent race colonize the galaxy”, etc.
If that is so, Eniac, then there is no Fermi paradox, which is what I was trying to say the whole time.
Then there could be scores of intelligences which have just never made it to the stars (yet), because interstellar travel poses such enormous obstacles that the *chance* of achieving it is simply very very small, or, in other words, from a perspective of natural selection, interstellar species are extremely rare, too rare to have appeared among the relatively small number of intelligences.
Again, my conclusion remains that the issue may not be so black-and-white (no aliens), but one of extreme rarity.
Therefore also, my conclusion also remains that your abiogenesis bet for the Fermi paradox is at least a bit premature. There are countless obstacles to overcome from habitable planet (through first life) to interstellar species and any of those obstacles reduces the remaining set of candidates, to the point where interstellar civilization may become rare even beyond one or a few per galaxy.
Eniac , ljk
If a ETI is hiding , has gone estinct ,or for som reason doesnt want to comunicate with us , it doesnt matter too much , because it has no effect , and there is nothing we can do about it without wasting resources better invested elsewhere.
That leaves us with only three relevant possibilities :
1 . life on earth is unike , a statistical almost-imposibilty
2. single cell lifeforms or otherwise LIMITED lifeforms exist on an unknown proportion of exoplanets.
3. toolmaking ETIs exist on other planets , but unknown factors prevent both comunication and interstellar flight.
When it is boiled down to these three possiblitiies , it seems that Eniac has a good case in arguing for number one as the most probable one , and perhabs also as the most logicly simple explanation .
With any luck at all , it should be possible to distinguish between 1. and 2+3 inside the next 30 years . The answer will then decide what the next question should bee .
One more thing about life in the universe and abiogenesis. Some here argue that the ‘belief’ in life in the universe also almost seems religious in nature, in view of the (perceived) minute chance of abiogenesis.
I strongly object against that for the following reason;
The real reason to be optimistic about life in the universe and to keep searching for it (a search which has hardly begun anyway) is not primarily its humongous size, as some would argue, but what we are incrementally discovering about its very *nature*.
Size alone would hardly or not be a comfort if the (rest of the) universe were fundamentally different from earth and hostile to life, e.g. the way people viewed it in the early middle-ages. In that case it would be like keeping on searching for (living) whales in the Sahara desert, simply because it is such a vast place. Even if it were endlessly larger, there would be no hope in this.
However, the more we learn and discover about the universe, the more we learn that it is fundamentally comparable to ‘our place’ and conducive to life: cosmological and Copernical principles, sunlike stars, terrestrial planets, water, organic compounds, …
There may be hurdles to take, but no real showstoppers. As I have argued before, everything seems to be a matter of graduality (more and less similar, ranges).
This is what makes the search for life in the universe a real and fascinating scientific possibility, and NOT a belief system.
It is an enormous quest, but not hopeless like looking for whales in the Sahara, but rather like looking for oases.
I admire your faith in this, especially when it comes to abiogenesis. I hope we will soon discover evidence that shows you are right.
from ljk’s link: “its frequency of 1420 megahertz has interested scientists, as it is a main frequency at which hydrogen, the most common element in the Universe”
In other words, it’s extremely likely to just be some natural assemblage, a cloud or similar, containing hydrogen, and temporarily or periodically energized by some other natural phenomenon to give off the detected radiation. It’s a very stupid idea to transmit at a naturally common frequency, as I’ve already stated. An intelligent species actually trying to communicate would use frequencies not given off by common molecules, to avoid interference and allow their signal to be picked out from the natural din. But I guess again like elves and fairies, they are trying to look perfectly natural rather than actually trying to communicate.
Ronald said on February 10, 2012 at 11:20:
“One more thing about life in the universe and abiogenesis. Some here argue that the ‘belief’ in life in the universe also almost seems religious in nature, in view of the (perceived) minute chance of abiogenesis.”
That is another tactic the fundamentally religious use on the concept of alien life and science in general, by trying to turn them into just another form of religious belief. This shows they either do not get what science is all about, or they do not care as they conduct their propaganda campaign – a kind of scorched earth policy as they continue to lose ground to real scientific discoveries since at least the era of Copernicus and Galileo – or a combination of both.
Equating aliens with fairies, elves, and other mythological creatures is another tactic. This also displays more evidence that many comparatively primitive, provincial humans are actually afraid of what real aliens might mean in regards to our species’ place in the Cosmos and what the advanced ones could do to us – even though we appear to have been left alone by any and all ETI so far as we can tell.
Eniac – I know you may consider this heresy (yikes, shouldn’t use that word!), but I believe – I mean think/conjecture! – but just because an ETI may have the mindset and ability to explore and colonize the entire Milky Way galaxy, that does not mean they necessarily would or could do it.
400 hundred billion star systems separated by light years of deep space is a lot of worlds to reach, I don’t care how much time one has on their hands (or whatever appendages). Earth and the Sol system could have been one of those places that the ETI just did not get to either on purpose or because there were so many more interesting and appropriate worlds to explore and settle.
Now, granted, we have not really explored our celestial neighborhood with the kind of detailed approach required to see if any ETI left something tangible behind, so the game is still afoot – or whatever appendage.
ljk: “Equating aliens with fairies, elves, and other mythological creatures is another tactic. ”
I assure you that I am not doing it just for the chuckles. I am doing it to demonstrate that you, like the believers in elves and fairies, are not doing science. You are merely believing and trying to find any shred of extremely indirect evidence (e.g. the commonality of simple molecular “building blocks of life”, the frequency of “habitable planets”, and so on) to bolster your preconceived opinion.
In particular by putting forth, like the believers of elves and fairies, that ETI are good at hiding, and leave their natural environment undisturbed, as an excuse for why in petabytes of astronomical data we observe not a shred of evidence for artificial surfaces or radiations, you make your “theory” profoundly unscientific. Here is what Karl Popper (whom scientists respect right up there with Occam as describing how to do science) had to say about it:
“it must be possible for an empirical scientific system to be refuted by experience.”
“Irrefutability is not a virtue of a theory (as people often think) but a vice. Every genuine test of a theory is an attempt to falsify it, or refute it. ”
“In so far as a scientific statement speaks about reality, it must be falsifiable: and in so far as it is not falsifiable, it does not speak about reality. ”
So what is the experiment you are proposing that if it goes as you do not expect will make you change your mind about your theory? I have put forward my theory: that civilization density is less than one per hundred galaxies. The test to try to refute it: look for evidence of ETI following the Malthusian imperative by engineering the surfaces and radiation emissions of other galaxies. If we discover artificial surfaces or illuminations in more than one per hundred galaxies then I am obviously wrong and must revise my theory to more common civilizations. And obviously if we found ETI in our own galaxy, extremely unlikely as that is, it would also change my mind in an even more radical way. My theory, being scientific, is open to all this.
But for your part, you haven’t proposed any experiments that would make you change your mind on your beliefs. As the negative evidence keeps piling in, you can keep hiding your religious faith, that we live in a galaxy full of aliens, in the supposed universality of ever more nature-loving and ever more cleverly hiding aliens. Until they become indistinguishable from elves and hobbits.
We have already established that the singular act of colonizing only a few (not billions, just the few nearest) stars, when repeated at reasonable intervals of thousands of years, will have the galaxy filled in mere millions of years. No intent, plan or long-term program beyond each single colonization event are necessary. Only a propensity among the daughter colonies to eventually do as their ancestors did. Your comments persistently appear to show a profound lack of understanding of this concept.
After sufficient time (a fraction of a billion years), there will be few uninhabited worlds left, and chances are that those will not be uninhabited for long.
@Eniac: I wonder, what the impact would be on the total colonization process of a galaxy, if the continuing ‘chain’ of colonizing nearby star systems was broken, either by local extinction of the civilization (and repeatedly so after any re-colonization due to unfavorable local conditions), or because the gap between neighboring inhabitable systems is too large to bridge. There may be significant consequential differences whether there is say 3 ly between two neighboring systems or 30 ly.
Could this result in parts of the galaxy remaining uncolonized?
@Ronald: “Chain” is the wrong image here, rather we have a 2-dimensional frontier between inhabited and uninhabited space. Each uninhabited system near the frontier will have multiple neighboring inhabited systems. Whichever of those decides to colonize first will get the prize. Any failure to colonize, even if widespread, can always be “outflanked” by other regions of the frontier. In extreme cases of failure, there might be an uninhabited bubble for a while, which would eventually be filled by colonization from any of the surrounding inhabited worlds. Note that failure will only have significant consequences when it is coordinated over dozens of worlds, an unlikely occurrence given the difficulties in travel and communication.
It is, of course, conceivable that there are barriers in the form of large empty spaces (as you suggest) or dense interstellar medium or the like. These would eventually be completely surrounded, unless they bisect the entire galaxy.
Another thing to consider is that the galaxy is not static, but stars are being mixed up quite a lot. Even if my above reasoning were to leave open the possibility of partial colonization, mixing will ensure that any initially local configuration of inhabited space will be distributed over the entire galaxy in not too long a time. AFAIK it takes a small fraction of a billion years for complete mixing.
@LJK:
It is not heresy, in fact it is quite reasonable. I, too, do not expect all ETI to go on and colonize the galaxy, necessarily.
But let us go through your thoughts/conjectures: You think that we may one day contact ETI, perhaps even visit them. That would mean that there must be some in our immediate vicinity of the galaxy. This in turn means that there must be thousands or tens of thousands, at least, in the entire galaxy. Furthermore, according to your thoughts/conjectures, not a single one of them would go on to spread over the galaxy. Not one. Without exception, for billions of years. I am still looking for a plausible scenario for that. It seems like an enormous leap of faith to me.
@Ronald:
I’ll give you “scores”. Yes, it is possible that ETI exist but are sufficiently rare that none has gotten around to colonize neighboring worlds. We could be the first. First out of 20, that’s reasonable, somewhat. First out of 10,000 seems incredibly lucky. BUT, the 20 are likely spaced out over billions of years. Most optimitistically, let us assume that they are all still there, living their intellectually advanced lives for billions of years, forever constrained to their own planet and/or stellar system. They would still be spaced too far apart for us to make any meaningful contact with them. Things get even much worse if we assume that failure to spread may entail or be caused by a demise of the ETI, such that brief periods of intelligence are interspersed with long periods of “regular”, unintelligent life. Then each such period would have to be counted as a separate ETI, another “try” if you will, and there could have been only scores of those throughout billions of years of galactic history. Those would definitely be way out of reach to us, in time as well as space.
In the best case, to go with Nick’s very relevant comment on falsifiability, we will have evidence of such rare ETI only after we are well into our own expansion into the galaxy, having covered a sufficiently large fraction of it to be likely to encounter one.
To save SETI it is time for me to reiterate my rare Sol hypothesis. This is based on three simple premises, and would solve the Fermi paradox.
1 Abiogenesis is rare.
2 Lithopanspermia works efficiently within one system
3 Eniac’s magnificently bold suggestion the evolution always leads to intelligence [if physical conditions allow].
Many things arise from these assumptions. We see that there must have been life on Venus, Mars, and Europa billions of years ago. More importantly, in the distant past each of those worlds has been postulated to have gone through a phase of high oxygen levels. If one of them really did, and if it lasted for long enough, intelligent life would had developed there, and most probably gone on to colonise the galaxy.
Now Eniac has also pointed out that sites of failed colonisation could only temporarily disrupt the colonisation process, and would eventually be recolonised from other locations. However, in my rare Sol hypothesis, there is one location that every single independent colony will think is already colonised, and they might even share a religious prohibition of returning to – Sol.
Surely that is the least implausible scenario that would re-enable SETI so far.
Let me just preempt the impression that I am against SETI. To the contrary, SETI is an important experiment that, if successful, would immediately and thoroughly falsify my theories and conjectures. It therefore needs to be pursued.
“rare Sol hypothesis.”
Very entertaining, but I’m afraid I find a number of questionable parts of it that multiply out to overall implausibility. First, I’m skeptical that the ancient timeframe of metabolic innovations, all prerequisite of the later rise of higher life forms (nitrogen fixation, photosynthesis, aerobic metabolisms, etc.) would all have occurred independently on the other planets — or if the occurred on one planet and then spread, if that leaves enough time for higher life forms and intelligence to evolve on Venus and Mars before they took their more modern life-hostile forms.
Another reason is it assumes that all the ETI, despite a predilection to spread across the galaxy, don’t like to alter their stellar environments to build Dyson structures or anything similar. The capability to build starships large enough to carry a self-sufficient economy very strongly suggests the capability to capture most of the sunlight that natural solar systems so profligately waste. But we see no evidence for this in our galaxy. It all looks very natural, i.e. very empty.
Yet another reasons is no plausible mechanism is given for why these ETI would have gone extinct in our own solar system.
Furthermore, trillions of trillions of trillions of photons per second, containing detailed spectroscopic information about the surface material composition and illumination given off in one solar system are available for observation in nearby solar systems. And they could of course park probes in our own solar system. So if there are any of these ETI still around anywhere in our galaxy, it’s highly implausible that they are not monitoring their solar system of origin closely. So they would certainly know that it was no longer colonized, they would have followed the progress of the dinosaurs, the mammals, and would currently be very familiar with ourselves. I find it highly unlikely that any religious or legal taboo against contacting us, building religious shrines here, or even conquering us could be enforced. Cf. our own Holy Land, full of both shrines and conflict.
Yet another problem is that lithopanspermia is a very difficult process — it requires an entire closed ecosystem, not just an individual organism, to survive the radiation, reentry, and hard landing, and then synchronously disperse in an environment very similar to the one they left. Too much improbability is involved there.
Still, it shouldn’t be too hard over the next several decades to rule out that Mars, Venus, and Europa ever hosted higher (or any) forms of life, much less civilizations, so in that sense it’s a nice falsifiable scientific theory. (It’s already highly implausible that a civilization capable of building starships wouldn’t have left artifacts all over the solar system in place of the very natural looking surfaces of asteroids, comets, and planets that we actually see — in that sense it’s already basically been falsified — but further evidence further falsifying the theory can soon be readily found).
As for radio SETI, it’s a fool’s errand, not least of the reasons being that it can’t falsify the shy-green-elf theory that its proponents already rely upon. When we keep discovering nothing, the ETI just get ever more shy, ever more able to prevent each other from altering even a smidgen of their natural environment, and ever better at hiding. (Except of course for their odd preoccupation with an inefficient form of communications that briefly dominated Earth communications during half of one century). But probably the biggest reasons is the scope of the search: the odds of finding ETI somewhere in a hundred billion galaxies is trillions of times higher than the odds of finding them in our own galactic neighborhood. Radio is to infrared/optical spectroscopy for SETI as donkey carts are to the sailing ship as a vehicle for discovering new worlds.
Eniac:
“In extreme cases of failure, there might be an uninhabited bubble for a while, (…).
It is, of course, conceivable that there are barriers in the form of large empty spaces (as you suggest) or dense interstellar medium or the like. These would eventually be completely surrounded”.
Yes, this is exactly what I meant, simple and straightforward (too great) distance between habitable planetary systems may create uncolonized ‘bubbles’ as you call them (I like the expression).
In your next comment you rightly and interestingly mention the mixing up of stars during their galactic orbits. However, although I do not have any figures and am willing to be corrected here, my impression is that stars, especially those with more or less circular orbits in the galactic disc, can stay in their stellar groups for quite a while and do not mix so rapidly.
Those uncolonized bubbles might form a (partial) explanation for the Fermi Paradox, at least with regard to physical colonization, of course not with regard to communication.
If this is true then one may expect more K1/2 civilization and colonization in multiple stellar systems, (open) star clusters and toward the inner galaxy (but still safely far away from the core).