Extraterrestrial life
On whether life exists somewhere other than Earth, there are simply too many unknowns at this point to say. Arguments along the lines of "there are so many whatever-illions of planets in the universe that there must be life elsewhere" cut no ice with me. While we understand evolution (which governs the development of existing life) quite well, we know much less about how the first self-replicating molecules arose from ordinary chemistry. That might be a very low-probability event, so low-probability that even in a universe of a trillion galaxies with a trillion planets each, it would happen only once. Until we've actually discovered life (or explored a wide range of solar systems and failed to find any), we have no data or even much basis for hypothesizing.
Certainly if we find life, even mere bacteria, on some other planet or moon in our own solar system, and can confirm that it originated independently rather than spreading from Earth somehow, that would be evidence that life is very common, since it arose twice in one solar system. So continued study of such prospects as Mars and Titan is very valuable -- finding life in one of those places would tell us something about the whole universe. Seeing what differences and similarities it had with Earthly life would also tell us something about the range of types of life that can exist.
Complex life, in the sense of a biosphere with plants and animals comparable in size and variety to Earth's, would obviously be a much more interesting possibility. We can already be pretty sure that this doesn't exist on Mars, though (multiple rover missions have seen no trace of animals or plants), and the prospects for the moons of the outer solar system don't seem good -- being so far from the Sun, they don't receive as much energy to power an ecosystem as Earth does. But it can't be completely ruled out. We have plenty of examples here on Earth of how evolution can adapt animals and plants to what seem like hopelessly hostile environments. If a future Titan rover sends back video of bizarre-looking animals and plants there, it will certainly rank among the most electrifying scientific discoveries of all time.
In the universe more generally, again, right now we have no data to judge how common complex life is. Even if basic bacteria-like life is common, a "Cambrian explosion" jump to large, complex plants and animals may still be very rare. Or it may be almost inevitable given enough time. Right now we simply don't know, and it will be a long time before we or our machines can visit the planets of other stars to find out. One thing I'm pretty sure of -- if alien complex life does exist, it's really alien.
Intelligent life, in the sense of life intelligent enough to create a technological civilization, is a very different question. I feel on firm ground in believing there almost certainly isn't any.
We humans have been systematically developing technology for only about four hundred years, and that has been enough to get us from believing the Sun and planets orbit the Earth on crystal spheres to creating the internet, space probes, and the Large Hadron Collider, and understanding physics down to a very fundamental level. Given that the universe is billions of years old, if there were (say) a hundred technological civilizations in our own galaxy, the odds are that many of them would be millions of years older than we are, some of them tens or even hundreds of millions of years older. Knowing how far our technology has come in just four hundred years, it's obvious that a civilization which had been progressing for ten million years would be doing things we could easily see and recognize as the unmistakable work of intelligence, even if they were located on the far side of the galaxy. We see no such works. In this case, absence of evidence really is evidence of absence.
(I don't buy the idea that all civilizations self-destruct at some point and therefore never progress to such a level. Evolution tends to imbue complex life forms with a strong urge to self-preservation, and beings intelligent enough to build (for example) nuclear weapons would also be intelligent enough to figure out how to minimize the dangers they present, as we ourselves have done. Civilized species which evolved on different planets would all be quite psychologically different from each other. Some might indeed self-destruct, but it's absurd to postulate some flaw afflicting every single one of them so fundamentally as to make self-destruction inevitable.)
Maybe this absence shouldn't be surprising. Even if complex animal life is common in the universe, I see no reason to think that natural selection usually favors development of high intelligence. Intelligence doesn't seem to have much survival value until it reaches the human level. Highly-intelligent animal species such as chimpanzees or elephants are not notably more successful in the wild than the dumber animals around them.
Here's another way of looking at it. If that hypothetical 10,000,000-year-old civilized species elsewhere in our galaxy which I mentioned above actually existed, they would have spread out and colonized the whole galaxy about 9,900,000 years ago, and we wouldn't even be here because we wouldn't have gotten the chance to evolve in the first place. Given enough time, a technological civilization would eventually spread through the entire universe, and that might not take as much time as you'd think, if a solution to the problem of travel being limited to the speed of light is possible.
If one assumes the universe contains a billion planets which would each produce its own technological civilization if left undisturbed to develop, then the appearance of those civilizations over time probably follows a bell-shaped curve distribution -- that is, a few planets will develop much earlier than most of the rest, with the very first one likely being tens of millions of years ahead of even the second one. So the first technological civilization to appear will spread out and colonize the universe in less time than it takes any of the others to develop at all -- which means that none of those others ever will develop. They'll have been pre-empted by the first one. The first technological civilization to appear in the universe will be the only one.
The fact that we do exist means that we just happened to be the first. If we weren't the first, we wouldn't be here at all.
posted by Infidel753 at 3:13 AM
17 Comments:
Maybe other civilizations could care less about spreading out and colonizing.
I normally agree with you on most everything, but your premise of first and only, I don’t. And reason being space and time.
Some planet has to be first, obviously, but this could have occurred millions, if not billions of years ago and yes they could have spread to their own galaxy and maybe a few other closer ones, as well. But they’d still be limited to the immense vast reaches of space, like say their local group.
So somewhere else far far away, another "first" would be occurring to spread into their local group and the two shall never overlap. And these other "firsts" could also occur much much later in time and yes even much earlier, so the notion of 'first' due to time relativity, would be a moot point. It’s all relative.
There are great spaces between local groups of galaxies and also even more vast reaches of nothingness. And due to the expanding universe, these spaces enlarge to further make further spread of a particular technological species become even more difficult.
I think there are others either long ago, or perhaps similar time frames as "now" and others that will develop far far into the future.
In time the night sky from here will have less and less stars to observe as the expansion continues. And even now we only see a part of the universe, just the observable part and there’s much more we will never see. Expansion and the speed of light will see to that.
Just my thoughts...
I kind of agree with you: wouldn't we have had some sort of breakthrough by now if there were extra terrestrial life? Well, besides the accounts of cows being sucked into flying saucers and the alien abductions? It all sounds very sketchy to me.
Like you say, if there were intelligent life in the universe, they would have spread out thousands if not millions of years ago.
I also think that people kind of trick themselves into thinking that extra terrestrial life would look anything like us. Nope. Not happening. Now I wanna watch that last Alien movie.
XOXO
Interesting read. I do not spend much time pondering the existence of extraterrestrials. However, I do think their is a greater probability of their existence than that of an all knowing, all powerful, magical being.
Thanks for the comments.
Fly: Some might not, but I really doubt that's common. Civilization tends to spread. If some civilizations never spread out no matter how old they get, one could say they don't really count as civilizations for the purposes of the argument. The first civilization that is expansionist will spread through the universe before the next one appears. I suppose it's possible that as we spread out we might encounter and engulf such an ancient stay-at-home oddity somewhere, but it just doesn't seem likely to me that even after millions of years an advanced species would never feel the impulse to expand.
Mary: That would be true if -- but only if -- it's never possible to overcome the problem of travel being limited to the speed of light. To me it seems unlikely that in just a few centuries of systematic science we've discovered a problem that thousand or millions of years of further progress will never be able to solve. I'm no expert, but I think at least some informed opinion believes the Alcubierre drive is theoretically plausible, even if we're nowhere near being able to build such a thing. If so, even intergalactic distances and the size of the universe as a whole are not an absolute barrier, given enough time.
Sixpence: You may recall I wrote about those alien-encounter tales here. Alien Resurrection wasn't a big hit, but it does have its enthusiasts. I found it intriguingly weird.
Lady M: Thanks. That's certainly true. A god anything like the Judeo-Christian one would certainly manifest even more evidence of its existence than advanced aliens would.
They're working on it. https://www.forbes.com/sites/startswithabang/2019/06/28/this-is-how-physicists-trick-particles-into-going-faster-than-light/?sh=b0125ba462c1
[Looks around]
You call this civilization?
I like the logic. Puts a new spin on ET life that I haven't heard before. You're tarnishing my fantasy, however, that given nearly infinite time and space, my essence will someday reconstitute in the universe. :-)
You say that "civilized species which evolved on different planets would all be quite psychologically different". Yet, you discard the notion that there could be an advanced civilization, different from ours, that fails to populate every corner of the universe. These statements seem to be at odds. What if the earth is just a petri-dish or a prime-time reality show for a more advanced species?
Ignoring much of your excellent logic, I tend to think (and by "think" I mean "want to believe") that there may be other advanced civilizations in faraway galaxies. However, we are so far from having the technology necessary to locate them that we should not waste a lot of time and money trying to do so. There are too many mysteries here on earth that still need uncovering.
Thanks for redirecting my gaze for a short time beyond the earth's horizon.
Mike: Thanks, that's interesting -- but I had rather hoped to do it by speeding up our spaceships rather than slowing down the light.
Anon: Compared to the historical alternatives, definitely.
Carol: Thanks. I like to think my thinking runs in somewhat novel channels. As to being reconstituted in the future, I believe it's actually quite possible, though for reasons rather different than what you probably have in mind. I hope it happens, though. We could get people like Jules Verne back as well.
I don't completely rule out the possibility of a non-expansionist technological civilization (see my response to One Fly) -- I just think it wouldn't be very common. The nature of natural selection does imply some pretty much universal traits, among them the urge to survive and proliferate, which would generally imply expansion, including into space once technology is advanced enough.
There are so many unknowns about alien life that any post like this is necessarily speculative. Any logic we use to predict its nature might turn out to be completely wrong for reasons of which we can have no inkling now. That's why future exploration will be so fascinating. Eventually, we will know.
Has all this talk about extraterrestrial life been occasioned by Avi Loeb? I'm assuming I'm not introducing a source that everyone has already seen and apparently discounted, but here's a relevant article. I find it fascinating that such a renowned astrophysicist--granted one who's taken unorthodox positions previously--is willing to stake his reputation on his belief in the certainty of our "close encounter." Audio included.
https://www.newyorker.com/tag/astronomy
"Eventually, we will know." I'm not sure who the we is in your conclusion, Infidel. I'd love love to be among those who find out, but unless Loeb is right, I don't count on breakthroughs within the next several decades.
Annie: I'm not too familiar with Loeb, but when a rogue scientist starts comparing himself with Galileo (and, implicitly, comparing the scientific consensus against his views with the Church's persecution of Galileo), that's a bad sign. It's the kind of thing the rogue scientists who reject evolution or global warming do.
By "we" there I mean the human race in general. Whether it happens in our own lifespans depends on whether, as I hope, we manage to cure the aging process and remove the existing limits on healthy life expectancy.
I am assuming Loeb is a bit “out there,” but I read about him around the same time that the extraterrestrial question seemed to gain popular currency. So I wondered about the connection. I do find much of interest apart from Loeb in The New Yorker article.
I must catch up on your writings about life extension.
Nan also recently posted about Loeb -- that was the first time I had ever heard of him. My comments on that post were rather on the tongue-in-cheek side.
Most of my posts on aging and life extension were a while ago -- there's a list here.
Recently, it has been proposed that we an locate intelligent life on other planets in our galaxy because we can detect signatures in their atmospheres consistent with the effects of industrialization as we would find in our own atmosphere. Of course, it should work both ways. If there are advanced beings elsewhere in our galaxy, they should be able to detect us by the same means as well.
If humanity ever does spread outside of our Earth, and then outside of our solar system, I think it will be similar to the Polynesian voyages in the Pacific. A band of humans will colonize some terrestrial body, and then after decades pass and their populations increase, some of them will then venture to another planetary body that can sustain life.
Fascinating speculations! Very interesting indeed.
I find myself in agreement that alien civilizations will likely be quite different from our own and may not find a compelling need to expand as humanity has. I think we have the possibility of being erroneous in our suppositions if we apply human motivations and psychologies to other advanced alien life.
Tommykey: That would work if the nearest civilization to ourselves happened to be at almost exactly the same stage of technological development -- meaning it was very close to us in age. Given the age of the universe, that's an extremely unlikely coincidence. If there's another planet within, say, 100 light years with a technological civilization, the odds are it's millions of years older and more advanced -- in which case, as I argue, we wouldn't even exist because that civilization would have spread to our solar system long before.
Darrell: Thanks. Again, I agree that some civilizations might not be expansionist, but I don't agree that none of them would be expansionist -- and it only takes one.
i think they came, they saw and said fuck this and left.
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