James Blish hinted at this idea in his classic story Surface Tension. He described the difficulties an intelligent aquatic species would have developing technology in a liquid environment.
I’m pleased to say that Mr Arthur occasionally sees fit to use some of my renders in his videos (with permission, of course). But not in that particular video, as it happens.
Brin has written at least one academic paper on the Fermi Paradox, and he is always interesting on the subject. But a waterworld might not be a good place for abiogenesis at all - the vast, deep seas would not present much opportunity for local concentrations of organic chemicals, so complex life may never develop.
Everything we think about this is necessarily speculative, but I don’t agree with your point. The vastness of interstellar space is absolutely a major issue working against the happenstance of intelligent aliens crossing paths, and there are several distinct reasons why the age of the universe is no help at all but only makes the problem worse.
First of all the possibility of life requires precursors that take time to develop. The universe may be very old but its life-bearing epoch is less so; we don’t really know how much less, but at the very least second-generation stellar systems with heavier elements and stars with lifetimes long enough to allow life to evolve are necessary. Intelligent life took four and a half billion years to develop on earth, and it’s been suggested that the universe may be just beginning its life-bearing epoch and that life on earth may be among the earliest in the universe.
The second problem is that you’re assuming that intelligent life, once formed, is more or less permanent. In fact, technological civilizations may have finite and perhaps not very long lifetimes in cosmic terms, perhaps the technology itself – such as nuclear weapons – becomes a self-inflicted limiting factor to survival. For any number of reasons, the happenstance of us crossing paths with an extraterrestrial species is rendered extremely improbable not just by the incredible vastness of space and the SoL implications of relativity, but further exacerbated by the vastness of time – it requires, as I suggested earlier, an incredible coincidence not just in three vast dimensions but in four. For all we know, for instance, there might really have been reasonably advanced life on Mars – we just got there a few hundred million years too late. Perhaps aliens may someday visit earth and find the same kind of wasteland, and wonder if there was ever life here.
If the argument had been that SoL is a problem, and this, combined with other problems we can speculate about, may be sufficient to explain why there’s no evidence of ETs then…fine.
No-one would dispute that this is a possible (broad) answer to the Fermi Paradox.
But from the topic of this thread, and the context in which we were talking, the vastness of space was being proposed as an explanation in itself.
But it alone doesn’t work for this purpose, for the reasons I gave. And the fact that you’re adding on extra “What ifs” shows that you agree with me: it’s a tacit acceptance that the vastness of space is not sufficient explanation alone because there has been enough time for a species to colonize the galaxy.
As for “the age of the universe is no help at all but only makes the problem worse”, I think that’s a weird way of putting it.
As far as we know right now, there was plenty of time, even allowing for the requirement of a 3rd generation star. Now, we can speculate that there are additional constraints and requirements that mean that humans are the first. Maybe we were incredibly lucky that multicellular life took just a few billion years to arise? Sure.
But that can’t be used as support for the idea that the age of the universe “makes the problem worse”. We’ve made it a problem with ad hoc speculation.
It would be like saying the defendant is innocent, because he couldn’t have driven from his office to his home 3 miles away in a mere 5 hours.
Why not? Because…I dunno, maybe there was a herd of zebra blocking the road?
First of all, there probably isn’t A single “Great Filter,” but a series of them. We’ve probably knocked down oh close to a dozen by now, but some still undoubtedly lurk in our future.
I’d say the self-destroying one, which does exist for us, may not be an issue with a species who has a different evolutionary history (read specific and perhaps unique psychological complexes). Say they have more of a hive mind a la ants or The Borg or such, and they would not have to deal with all that.
It’s incredibly easy to underestimate the power of exponential growth. I mean, let’s take an intentionally low-balled example: assume that, within the next 100,000 years, we make it to two other star systems. For all we know, this is a very conservative assumption—even with existing, or theoretically plausible technologies, such as the Orion nuclear drive, we could reach the nearest star system in a time of the order of a thousand years. Then, assume that once we’re there, it takes another 100,000 years to build up some infrastructure, and send the next two ships to two star systems—that is, every 100,000 years, we double the number of systems we’ve visited.
How long would it take to visit all the star systems within our galaxy? Well, there’s some 300 billion stars making up the milky way, which we’re visiting at a rate giving us a factor of two every 100,000 years. So, after 100,000 years, we’ve visited two, after 200,000 years, four, after 300,000 years, eight, and generally, after n*100,000 years, we’ll have visited 2[sup]n[/sup] star systems. How long to visit all 300 billion? The base-2 logarithm of 300 billion is about 38; consequently, it’d take about 3,800,000 years to explore the galaxy.
So even with relatively conservative assumptions, it takes a space-faring civilization only about 4 million years to seed the entire galaxy with life; if we’re being ultra-conservative and just add an order of magnitude to be safe, call it 40 million years. (And here is a paper using a much more detailed model to arrive at a similar ~50 m year time for full colonization.)
Now, there are sun-like stars potentially harboring Earth-like planets a billion years older than our sun; the challenge is now to explain why it seems that, in all this time, no civilization has arisen on either of those to invest the—cosmologically speaking—relatively minor effort to populate the whole galaxy.
In other words, taking into account the size of the galaxy and the time it’s existed, we should absolutely expect it to be teeming with life; yet, that does not seem to be the case. This is something in need of explanation. The size of the galaxy isn’t the answer—it’s part of what makes this observation problematic.
Could something akin to the anthropomorphic principle be applicable here?
If we were close enough, in both space and tIme, to observe evidence of such an expanding civilization, then don’t the odds favor our system having been absorbed by it before we even had a chance to evolve?
Such isolated civilizations may be rare but they can only exist where they have the chance to occur without interference.
I was making two separate points and maybe I wasn’t clear. Point #1 is that the age of the universe isn’t much help if for whatever reason we are only now reaching the point where life-bearing stellar systems are starting to become widespread. Point #2 is that there are many potential reasons why many or all extraterrestrial civilizations may have only a limited lifespan, either because they die out or perhaps because they evolve into beings whose forms and motivations would be incomprehensible and meaningless to us. If either is true, then to encounter extraterrestrial life that is meaningful to us requires the appropriate coordinates both in the vastness of space and the vastness of time.
I accept in principle your math on exponential growth but not necessarily the plausibility of the assumptions behind it. Yes, there is something in need of an explanation, but any number of such plausible explanations are easily found.
Just for starters, I think any plausible theory of our place in the cosmos must be premised on the idea that it’s statistically improbable that we’re unique or even particularly special, but what if that observation extends not just to the elemental makeup of the solar system and earth’s biological processes but to our chronological place in the universe – what if, in other words, life developed here when it did because in the evolution of the cosmos and its star systems it’s only been within the last few billion years that conditions for advanced life started to become relatively widespread? If so, alien civilizations would still be relatively young and not necessarily much more advanced than our own.
Or consider the problem that your exponential growth scenario implies an extraordinary degree of commitment for orders of magnitude longer than all of earth’s civilizations have existed all put together. It requires, in fact, something like a genetically driven obsession by an advanced civilization to do nothing but propagate itself from star to star, essentially eking out its existence living on interstellar starships for that sole purpose. It assumes that an advanced civilization capable of doing this would have the motivation to engage in this extraordinary venture, to maintain that motivation through many millions of years of change and evolution, and moreover, to replicate that motivation identically across billions of disparate stellar colonies with totally independent paths of social and biological development.
For all of those things to be simultaneously true seems unlikely. If you look at our brief civilization here on earth, you might argue that to some degree we’ve always had an urge to explore, but we’re also divided into a few dozen major nations and a great many smaller ones, all with different cultures and ambitions; only a very few, mainly the US, are doing any significant space exploration, and even there, the priorities have changed very significantly over just a few decades and will likely change again. A few folks are obsessed about going to Mars and beyond, but most of us are more concerned about the mundane aspects of our own existence; and while many of us care deeply about the advancement of science and human knowledge, that isn’t synonymous with trying to colonize the planets or building a starship.
So what I’m saying is that explanations for why we don’t observe the galaxy teaming with life are not hard to come by, and that among the most plausible are that life isn’t quite there yet, or that even if and when it is, it requires some pretty drastic assumptions to believe that the primary motivation of such life would be to single-mindedly dedicate itself to replicating itself among the stars. An alien civilization similar to ours might be more interested in the economy and staying home to read a good book, while a much more advanced one might have interests that are impossible for us to understand – or for us to detect.
An interesting discussion people, but do you think the idea that wood is unique to Earth has any merit?
[period added as part of snippage]
But WI our presence is predicated on overcoming a series of highly improbable events, the product of which would beggar the imagination if we knew just how improbable they were? [Yes, alluding to the Drake Equation] I think you are incorrectly applying the Mediocrity Principle here, in yes a post hoc way. Your premise in other words stands on very shaky ground. We may be talking about being the winners of a cosmic lottery many orders of magnitude more improbable than say Powerball odds.
In that sense, I think that we are indeed unique, at least functionally so. [If this was an IMHO thread, I’d say that we are the only technological civilization within at least a 100 million light year radius.]
I get your point(s), I think you still don’t get mine.
What I’m saying is, several people were just mentioning the vastness of space, and SoL speed limit, as the primary reason we have seen no evidence of ETs.
But when you crunch the numbers, you see there has in fact been plenty of time for a species to leave their mark across the galaxy.
Now, sure, if we add on some ad hoc speculation, we can come up with reasons why the time may not be sufficient after all. Or they may never have tried to leave a mark.
But of course, we can defend *any *hypothesis, indefinitely, if we’re allowed to arbitrarily add on speculation.
And in the meantime, the fact we need to “add on” like this, tacitly concedes that the math doesn’t support vastness of space and SoL being sufficient explanation in themselves.
Well, did you notice my point upthread?
Since everything sentient species do is super fast compared to geological timescales*, even if it took a hypothetical species 10,000 times as long as humans to discover fire, or utilize alternative energy sources efficiently, it wouldn’t make a jot of difference in terms of the Fermi Paradox.
- Obviously basing this on humans. If we want to propose that humans are unusually smart and usually species take far longer to solve problems, then that’s a different Great Filter proposal.
My main response to that is a rather incredulous “what??” You state, without basis and without evidence, that our presence is due to “highly improbable events”. You cite the Drake Equation whose major components are highly speculative and which was only ever intended to stimulate discussion, nothing more. You then claim that for these reasons I’m “incorrectly” applying the Mediocrity Principle, where in fact to the extent that I’m aligned with such an argument at all I’m saying in effect that yes, if you take a random sample of something you’re statistically most likely to find its various elements in proportion to their relative abundance, which is a straightforward observation based on some simple assumptions about homogeneity, and is not rocket science.
And then you conclude with a final paragraph that states as fact something that is pure conjecture, supported by no evidence, made even more ridiculous by putting a specific number on it, a number based on nothing at all. Yet you’re going to argue with a simple statistical observation that is supported by the fact that hundreds of planetary systems have now been discovered, and on that basis it’s fair to extrapolate the fact that the majority of the galaxy’s 300 billion or so stars have planets, many of which are in habitable zones conducive to life.
I of course was referring to the “anthropic principle”, not “anthropomorphic”. Stupid auto-correct.
No, I get your point. It’s this business of characterizing the vastness of space and SoL as “being sufficient explanation in themselves” that I have something of a semantic quibble with. You make it sound like I’m inventing “add on” reasons to try to show why this would still be implausible, like when you said “It would be like saying the defendant is innocent, because he couldn’t have driven from his office to his home 3 miles away in a mere 5 hours. Why not? Because…I dunno, maybe there was a herd of zebra blocking the road?”
But it’s the other way around. In order to support the “exponential growth” theory, as I see it, you’d have to assume the kind of extraordinary technology, methodology, and civilization-wide motivation I referred to before, sustained across many millions of years and promulgated across billions of separated and independently evolving successor civilizations. I happily concede that if there were a civilization old enough and advanced enough and obsessed enough – at a fundamental genetic level – to do this, it physically could happen. It just seems to me (a) to be incredibly unlikely, and (b) I question the assumptions we implicitly make about what we would expect to see.
What, indeed, would we expect to see? Would we expect to see aliens in flying saucers planting flags and then trying to colonize us? That’s far too anthropomorphic. Maybe some advanced species has already done it, at least to a partial extent, and maybe their mission was to find habitable planets and seed them with life, and then move on. Maybe our benefactors or their robotic proxies have already been here and given us their greatest gift, and need not come again for a very, very long time.
How long does it take to discover fire (by a species capable of doing so) if there’s no such thing as wood around? If there’s no such thing as wild fires sparked by lightning or volcanic activity? Humans needed fire to evolve into our present form; could a species that didn’t need fire (because their ancestors had to survive without it) ever devise something as relatively complex as an oil lamp? Without wood how do you bridge the gap between a theoretically flammable substance and an ignition source?
I haven’t mentioned the “exponential growth” theory, nor had anyone else at the point where the claims about the vastness of space, that I’m replying to, were made.
As far as imaging some super-uber-duber species…not necessarily. Humans are already pretty close to a point where we could seed the galaxy with junk.
So, no, I don’t think those who think the Paradox is still a problem are making lots of assumptions.
No, we certainly are not. To date, we’ve barely sent one probe into interstellar space, and it would take tens of thousands of years using conventional propulsion to send a probe to the nearest star, over which duration it would certainly not be operable. We are nowhere near the capability to send probes to explore even the stars in the local neighborhood and have them communicate back.
We cannot even communicate very clearly with closely related mammalian species, and yes, species such as wolves, ursines, and primates do communicate, if not with the complexity of grammar we enjoy. After decades of professional study we still don’t know whether the clicking, squeaking, and singing of various cetaceans represents a complex grammar, although the complexity and evolutionary development of dolphins and whales would certainly support the hypothesis that they are capable of advanced cognition, conceptual thought, and complex verbalization that are hallmarks of language. And these are species that we have at least a common biology and basic senses. There is absolutely no guarantee that an extraterrestrial form of intelligence would have much of anything in common with us beyond physics and chemistry; they may not use DNA, they may not have eyes or ears, and they may not use anything we think of as language. They could communicate by building and sharing complex proteins or even direct transmission of cognitive patterns which would be beyond any foreseeable ability of us to even observe or effectively decypher. These are far from “Easy Problems”, as you dismissively label them.
No. Any life that is photosynthetic and carbon-based will likely have some analogue to wood or woody plants which, if they are in an oxidizing atmosphere can combust. Fire is actually more important to the biosphere overall than it is to us in particular, because it is a way to clear old growth or diseased biota and return the basic elements back to the biosphere in an available form. And while fire is a crucial element in our particular evolution, it is not the only means to concentrate and release large amounts of energy. Imagine a species which developed on a world where large concentrations of radioactive and fissile elements are readily available; they might go directly to nuclear fission (and have natural protection against radiation damage) allowing them to forego combustion as a power supply, and especially if they have evolved in an atmosphere in which free oxygen or another strong oxidizer such as chlorine is not readily available. That it is almost impossible to imagine what such life would look like (based on our experience) should not be viewed as anything other than a lack of data to infer from. We are only special because we’re the only life we know, but not only have we not been around the block, we’ve barely opened our eyes and haven’t even gotten out of bed in the scheme of exploring and understanding the larger universe.
Stranger
Supposedly gamma rays were much more common for the first 9 billion years of the universe, and that could have been a major great filter. Multicellular life (which is needed for intelligent life) couldn’t develop because a gamma ray burst would kill it off before it could reach the point of a singularity or interstellar travel.