The Foundation series is my main imagination pump here (it gets me thinking about this stuff):
This is one of the most interesting empirical questions, if there is life or not outside of us, but it seems like there must be.
And if there is extra terrestrial life, there are probably large clusters of it because of confounding reasons, like stable stars making it easier for multiple planets in system to be habitable, somewhere out there.
We probably know we are not close to a ‘large cluster’, because we’d know by now by the local nature of clusters.
So I think we can/should be in the headspace of the Foundation series. There are almost assuredly large clusters of power, and we are not part of it. The clusters know this state of affairs and so do all the outlier planets like us.
I’m not saying we should remain hidden or anything. I’m not even sure what the consequences are in this headspace. But I think we can and possibly should start realizing we’d be in contact by a cluster rapidly, if there were any in our Galaxy.
That dynamic just seems so inevitable and Asimov was able to capture it. The clusters will heavily cluster and remove most outliers by absorbing them. And the real outliers are very far between.
He is using logic which is from our current planets situation , technology situation , culture situation which could be completely different from a different species deciding if trying to contact another civilization makes sense. Also, even if this is most likely, the amount of time we have to observe visitors is very limited relative to millions/billions of years of existence, plus, there are trillions of planets that may have life that may or may not interest these guys. All in all it only proves how unlikely we will be visited but doesn’t say anything about if life is out there or not.
I know this is not really your argument, but I think it's related:
I don't buy that the problem is that we just don't know what to look for. There must be some observable characteristics that indicate its presence. It seems implausible that intelligent life forms would not leave any visible traces and that their planets would be indistinguishable from uninhabited ones.
They aren't... from nearby. Cosmic distances are vast and the telltale signs are small. I'm not sure we would have detected an abundance of sealife deep in Titan's oceans or fliers deep in Saturn's clouds.
I once looked into the reach of the Arecibo message; I can't quite remember the numbers but the main point stands: it's indecipherable but detectably artificial after a short distance (guess: 60-100 lightyears), and no longer distinguishable from natural radiation after about 5× that (guess: 250ish-600 lightyears).
The point is that even an intentional message quickly (in cosmic terms) becomes gibberish and, fairly soon after, too faded to even recognise as being a signal. On top of that, the receivers would have to be looking.
Basically, I doubt we would recognise artificial signals intentionally sent to us from further than 15 lightyears out except with much, much luck. That explains why we didn't find any clear non-intentional signals yet.
An interesting take on this is to flip the question: from how far away would we, with our current approaches, be able to unambiguously, definitively detect life on Earth? And intelligent life?
I'm not sure we're able to do even the former from Pluto, let alone from the interstellar medium.
> I'm not sure we're able to do even the former from Pluto
We can communicate with Voyager 1 beyond the limits of the Solar System, so I am not sure if earth's constantly emitted signals would not be detectable from Jupiter.
The ability to communicate with Voyager is a function of the transmission and reception system. We have to send an incredibly focused transmission to Voyager for it to pick up our signal and listen with very sensitive instruments on a long temporal baseline to detect Voyager's signals.
The inverse square law tells you that the flux of a signal decreases at a square of the distance. A receiver 2 miles away from a transmitter will receive a signal at a quarter of the strength of a receiver only a mile away. Our broadband omnidirectional broadcasts don't actually reach very far out into the solar system let alone the galaxy. Only very powerful narrowband signals reach very far and those are very directional.
If you were Montezuma, would you prefer to advertise your presence so that it would be visible from Spain, or would rather try to conceal your presence?
I think there are inevitable outcomes we can predict early on which are not sensitive to these considerations. You might think I’m doing a ton of guessing and hindsight reasoning, but I do want to at least say one of the principle characters in Foundation is someone thinking sociologically/cosmologically on 30,000 year scales. He wants minimize the future inevitable cluster collapse of the galaxy. He knows it’s unavoidable in the future, that space is subject to certain governing processes which will drive all starting points to the same collapse. At best he can minimize. By a magnitude of 1 or 2.
The Fermi paradox can be outmoded or not really relevant at these scales.
I avoided raising any particular outcomes other than the one thing which seems inevitable, the cluster-outlier dynamic. It’s weird this reasoning exists, or it was at least interesting to Asmiov imo. I think he found most interesting that a few distant inevitabilities can be known, and space-wise those relate to the cluster/very very few outliers.
And I’m pretty sure there were aliens (The M**). Asimov was both relying on human sociology and history AND taking that to the largest backdrop. Like only needing a slice (statistics, modeling, or selective deep-thinking even) of something deep gain to gain immense wisdom about the future. That was the most interesting thing about the character who set the whole story in motion at least imo. Even the initiating character, The M**, and counter forces could not disrupt the course…No planet perpetually hidden, no stopping perpetual clustering…(sorry for spoilers)
I sometimes wonder if the simplest answer for this is that nature / evolution obeys some principle of simultaneous discovery[0][1] and convergence. In which case all advanced civilization may simply be on roughly the same timescales.
In another words, it’s possible that all intelligent life is more or less at the same level of development, and this creates a situation where we only discover each other at the same time
That feels incredibly unlikely. The universe is billions of years old. There was nothing preventing an intelligence from developing on Earth a billion years earlier.
That being said, our civilization got an enormous boon coming later in the history of the planet. Fossil fuels and the abundant energy economy would not be available without the right biologic circumstances (eg lignin metabolism developing late) and timing.
Calling it the Fermi "paradox" really seems like begging the question to me. You've got a theory ("this math says life should be common") which conflicts with observed reality ("we don't see shit!"). Is that a paradox? It seems more like an invalidation of the theory to me. The resolution to the "paradox" is realizing that something in your theory is wrong.
What is the common refrain? If the facts don't fit the theory, then the theory is wrong! Isn't that the core essence of science? Empiricism is a repudiation of Platonic a priori reasoning. Beautiful and elegant theories that don't fit the facts are simply wrong.
The Foundation Series doesn't have any aliens because the humans created a bunch of robots that then decided to kill _EVERYTHING_ELSE_ in the galaxy to protect the humans.
Which novel is that from? It's been some years since I read any of Asimov's books, but the way I remember it is this:
In the Robot novels, the overwhelming majority of humans live on Earth in mega cities (caves of steel) with relatively few robots, and a small minority of humans live on a few dozen (50 or so) other worlds in highly roboticized societies. These humans call themselves Spacers and have very xenophobic inward cultures. In the extreme cases, exemplified by Solaris, they shun contact even with other Spacers from their own planet and surround themselves entirely with robots.
Eventually the human majority leaves Earth, because a robot following the Zeroth Law decides to irradiate Earth to force humanity to spread out in the galaxy. The humans from Earth don't take many if any robots with them and rapidly overtake robot-centric Spacer culture, which is all but forgotten (as are robots). The massive galactic human population of the Empire novels are the descendants of the humans that left Earth later, not the Spacers.
I don't recall that. I do recall some ominous foreshadowing regarding aliens in the final book*, but nothing definitive.
* Maybe D. should have thought about that possibility before embarking on a scheme that required hindering humanity's technical development for an indefinite period?
If you use Foundation as your pump you may enjoy John C. Wright's Count to the Escaton sequence. It's Foundation with aliens, logic, ethics, love, and scales of time and intelligence beyond anything else I have ever read.
N. B. It most closely resembles the part of Foundation where the Mule shows up.
I like how the SA observatory is known as Meerkat, given the comedic stance they take when on guard.
Otherwise, I always found favour (regrettably) with the argument that the amount of energy needed to transmit a signal across the galaxy was too great, as the intensity of the signal falls by the cube of the distance.
I’ve been following this topic for a long time, and I’ve noticed within the last decade or so, more and more people on this issue arguing that we could be the first intelligent species in the galaxy. For some reason, I’m very hostile to this idea, mostly given the age of the universe and where we sit in the light cone since the Big Bang. Are there any proponents of the idea that we are the first who can convince me otherwise?
Another idea of that seems to be trending in fiction for the last several decades, from the Culture series to the Three-Body Problem to Westworld, is the idea of the sublime, and the proposition that the so-called elder species would have transitioned and left our galaxy some time ago, hence why we haven’t seen any evidence for their existence. Could anyone also comment on this popular idea?
And in the end humanity will still only have been nothing more than some percent of a percent of a percent of its existence at best. And an individual human life so short someone could ask if you ever even existed at all.
I’m not a proponent of the idea that we are the sole intelligent species in the galaxy, but I think it’s at least plausible. In my mind it boils down to statistics.
Basically, it seems to me that many, many conditions have to come together for life to emerge at all on a given planet, and then many, many more conditions have to develop for intelligent life to emerge. If the denominator in that probability is significantly larger than the number of planets in the galaxy, then the probability of any given galaxy harboring intelligent species would be approximately zero. Similarly, the conditional probability that there are at least two intelligent species in a galaxy given there is at least one (namely humans here on Earth) is still approximately zero.
The galaxy is billions of years old. Human civilization is a few thousand. Human civilization with a significant radiometric footprint above noise is less than a hundred. And there's some not unreasonable concern that if we don't change our behavior en mass, the human race might cease to exist in a couple hundred to a thousand years. If that comes true, all of our human achievements will be a percent of a percent of a percent all throughout time.
I personally think there was civilized life long ago, but it died out fairly quickly, the same way ours might. Time and space are so vast that there can easily be million-year and trillion-mile gaps in between each attempt at life that gets far enough to meaningfully search for the existence of other life elsewhere.
Our universe is brutal and doesn't have any bias towards sentient life surviving. It does not care.
Yeah this is the heart of why the Fermi paradox does not convince me.
The vastness of space and time mean that there might have been millions of other civilizations that have reached our current level of technical advancement with no real overlap.
The number of stars in the observable universe is really big, but perhaps not as big as you are thinking. Wolfram Alpha gives it as 10^24, which seems like a ludicrously huge number. But suppose for the sake of argument that intelligent human life on Earth were the consequence of just five independent "one in a million" chances. That's 1 in 10^30. Just five independent "one in a million" hurdles to clear makes intelligent life unlikely to occur anywhere in the universe at all.
Now consider that advanced human life took a very long time to develop on Earth, even after multicellular life took off, which itself took a very long time to happen. Assuming that evolution inevitably converges onto something like humans is anthropocentric. It may be the case that life is reasonably common but intelligent life such as us is an absurdly rare fluke of luck.
The sun is apparently 4.6 billion years old, but the Milky Way is 3x that. Hominids for 6 million years? It’s not just about looking back in time, which our telescopes are pretty great at, but observing the place at the right slice of time which becomes much harder. We see proxima b as it was ~4 years ago. That star system might be 6 billion years old. What if their extinction event was 50 million years ago? Or 500 million? Or 3 billion?
I dunno—there's a lot that had to go right with the Earth for it to support not just life, but complex, high-energy life, which enables (expensive-in-energy-terms) intelligence. And it still came close to getting stuck in bad states that may have prevented that, at least a couple times. It's way more than just being the right size, the right distance from a not-too-dangerous star, and having water.
I'd be surprised if life isn't fairly common, but wouldn't be surprised if complex life is very rare.
> there's a lot that had to go right with the Earth for it to support not just life, but complex, high-energy life, which enables (expensive-in-energy-terms) intelligence
Like what?
> It's way more than just being the right size, the right distance from a not-too-dangerous star, and having water.
Besides that and having carbon (and nitrogen, I suppose), perhaps some small amounts of other elements, what are you referring to?
If it hadn't been for the K-T event wiping out the dinosaurs and creating a niche for mammals and eventually primates to thrive, we probably wouldn't be here.
It doesn't get discussed enough how much of a factor blind stupid luck was in the one example we have of the evolution of intelligence in the universe.
But the question was not whether we would be here.
What's to say that in the absence of the K-T event, some dominant dinosaur species wouldn't have eventually evolved their intelligence to our level? Perhaps even earlier?
It's not like the K-T event is a prerequisite for "general" intelligence, is it?
Perhaps in such an alternative universe where the K-T event didn't happen you'd be a dinosaur posting on Dinohacker News right now.
I don't know, dinosaurs were around for hundreds of millions of years or more, and while they evolved, they never evolved intelligence. It only happened when a catastrophic event disrupted the natural equilibrium. I can't help but wonder if intelligence isn't something that tends to arise under extreme circumstances.
there's really no saying. mammals have been around for ~180 million years, so ~112 million before the mass extinction. The dinosaurs were on earth for about 165 million years.
Given the relative quickness that intelligence exploded in later hominids, who knows. we could know about some gibbon analog in the dinosaurs right now, that given just a little longer could've made it to human levels of intelligence.
Basically we have a bunch of things going on that cause some graphs to cycle rather than run away, and if you break any of them—which can be as simple as tweaking a value here or there—most of our biosphere's gone.
Carbonate-silicate cycle breaking is what's considered the most likely thing to end complex life on Earth, for instance. All it takes to cause that is the Sun getting slightly brighter. In a few hundred million years it'll become increasingly difficult (inefficient) for plants to photosynthesize, reducing energy available to the biosphere, until finally photosynthesis stops completely.
So you're saying that in such a scenario, it would be impossible for complex life to exist, even if it looks different from the complex life we have now?
I am just wondering whether we are not confusing "complex life as we've seen to exist" with "complex life that can possibly exist".
For example, I am wondering whether the Great Oxidation Event is not a counterexample where we had a run-away biological process that caused a mass extinction (which, if it were possible for us to be alive at the time, might have looked like it would be impossible to recover from) but still lead to complex life existing despite oxygen being so toxic (at least from the point of view of the kind of life that existed at the time).
I know this is not the best example, as at the time complex life didn't exist yet. But I'm wondering if it wouldn't have been possible for complex life to exist in an oxygen-poor environment. Well, in fact some multicellular species that exist today are anaerobic and therefore do thrive without oxygen, right? Perhaps such anaerobic life would have evolved a lot more if our atmosphere had never been oxygenated.
Unfortunately I know nothing about the examples you mentioned, so I can't tell whether they are comparable.
Edit: I just read a bit about the carbonate-silicate cycle and I think I know what you mean now. Yes, if surface temperatures were more extreme it would indeed be quite difficult for complex life to exist (at the surface, at least). After all, some limits to the existence of interesting life must surely exist and temperature does seem like an inherent one.
Carbonate-silicate cycle breaking means photosynthesis can't, chemically, happen, not just that its being hotter makes plants less happy.
My point isn't that life can't exist otherwise (ocean vents exist—though, you do need an active core for that—and anaerobic life is a thing, as you point out) but that only certain routes, even assuming there are some wildly different paths that might work, will yield enough energy to support complex life. You need a system that's reasonably stable (i.e. tends to prevent a variety of runaway events, turning them into cycles instead) even when life itself is changing the environment. Sometimes life will step in to do that if you get lucky (as in the oxygenation crisis, which you mentioned) but the planet itself needs a bunch of stuff to be just right, too—not just conditions, but processes.
I suspect there are lots of planets with some bio-goo on them, maybe even quite a few with things as complex as some insects or crustaceans. I further suspect there are very few (perhaps about as close as one can get to "none" without reaching it) that could support something like (even for generous values of "like") our giant tree of vertebrates. Not enough energy available, or, there is, but the world lacks the processes to stop life's own effects from wrecking the environment and stunting its own potential.
Then there's the fact that even complex life doesn't seem to necessarily lead to advanced intelligence and civilization. I mean, look at how long it took humans to develop writing! All that other stuff had gone just right, and intelligence emerged, and we happened to be a tribal species (probably), but we still puttered around for, what, a few hundred thousand years? The dinosaurs had no space program, nor the birds, nor the whales, nor fish, despite existing for tens or hundreds of millions of years—intelligence and the right kind of cooperative pack/tribe behavior to let it flourish seems to be a really rare combo, even when everything else has worked out very well for complex life.
Oh I mean I could be way off, but the more I learn about how the Earth functions the more it seems like it's a whole bunch of spinning plates and upsetting any of them to the point that they stop spinning means the whole party (more or less) stops. There's certainly more to it than being roughly the right size, roughly the right composition, and in the "goldilocks zone". The only reason it works is that the plates (to continue the metaphor) self-stabilize when they get bumped, on account of the spinning. Take away even one of them and one of our cycles that keep things nice & cozy for complex life instead goes up-and-right or down-and-right... permanently.
Things like plate tectonics to periodically send material down to the mantle, pull fresh material back up, and pump all kinds of stuff into the atmosphere, are really important for maintaining long-term stability. Imagine how much less life the oceans could support without rivers dumping disolved nutrients into them all the time—and those rivers have nutrients to dump, even billions of years into our planet's history, because of plate tectonics, because there's a water cycle at all, et c.
There are other filters, too. Hard for an aquatic intelligent species to kick-start civilization—how will they get started using fire? One can come up with ways, maybe, kinda, but would they stumble on those methods the way we stumbled on fire, almost effortlessly (then still took many millennia to discover how to do much more with it than burn forests/grasslands, cook food, excavate shallow caves, and harden wooden points)? For some high-clouds ecosystems (as some speculate may exist) on planets that can't support (much) life at ground level... how would an intelligent species there build anything? The only materials available would be parts of other high-altitude life forms. That's assuming you could get enough biomass up there to supply the kind of readily-available energy and nutrients an active, complex, smart life-form needs to be able to gather from its environment in the first place. That sort of thing. Plus you're counting on the emergence of physical features necessary for tool use at all (like our hands) which is something that pretty much only climbing species develop, as a side-effect of needing to grip things all the time.
I think there are lots of things working against the emergence of not just complex life, not just intelligent life, but coordinated civilizations with long-term retention and transmission of knowledge that can accomplish things we might associate with advanced alien life forms. Even if life turns out to be very common, I expect complex life is not, intelligent life even less so, and civilization vanishingly rare. But, again, I could be wrong—it's all guesswork, really.
You seem to have created a little bit of a strawman in your first paragraph. You said that people are starting to argue that we could be the first in the galaxy, and then asked somebody to defend the claim that we are the first.
Honestly, I don't think we have nearly enough information to be able to put much confidence in our ability to calculate a meaningful probability of life currently. Drake's Equation is fine, but without any way to validate the coefficients, you can make it say anything you want.
I wonder why ideas in this field seem to be stuck with technolgy of the last century?
Sending some EM signal and hoping for an answer appears somewhat ridiculus.
If at all possible, you would go yourself or send an AI capable of doing some serious information gathering.
Now, why do people pretend, the time of travel was prohibitive? Not only does that rely on the weirdly self-centered assumption, substantial speeds weren't accessible, it also presupposes domestic time frames.
Lastly, the idea we should have been "visited" already.
This has the unspoken implication of some big vehicle appearing in the sky, radio broadcasts and TV crews gathering, etc.
Why? What sane entity would go about it in this manner?
>> Lastly, the idea we should have been "visited" already. This has the unspoken implication of some big vehicle appearing in the sky, radio broadcasts and TV crews gathering, etc. Why? What sane entity would go about it in this manner?
It’s that basically what happened in our planets ‘Age of Discovery’? Some European ship shows up on a shore/lagoon and ‘takes over’?
Europeans hardly had to do much to "take over" in the Americas. After the first few ships arrived, about 90% of the indigenous people died of smallpox and other infectious diseases. At that point the Europeans just walked into land that was largely depopulated and faced only limited resistance.
If aliens are so internally slow that a few hundred thousand years is not a big deal for them, they likely cannot develop quickly enough to achieve interstellar travel before their star burns down.
There are rather understandable limitations on the physical size of electromagnetic transmitters due to wavelength and power parameters. There are also size limitations for sensors: you cannot capture too few photons per second, else you will not register a coherent picture of faster-moving processes on Earth.
There are also limitations on the size and mass of a device that needs to slow down from interstellar speeds to take a reasonable peek at Earth.
Basically, physics as currently known to us does not allow for a grain-sized interstellar sounding craft that could transmit back much useful info, let alone to spread a lifeform.
> I wonder why ideas in this field seem to be stuck with technology of the last century?
SETI used to be focused on looking for RF carriers. Few modulation modes still in use waste energy in the carrier signal. In newer modes, a small amount of redundancy in the bit pattern provides synchronization.
Analog TV was 80% carrier, 20% content at megawatt levels, probably the most detectable signal ever sent from this planet. Hugely redundant and easy to decode. But now it's history. This planet emitted high-powered carriers for less than a century.
Modern RF signals look like noise unless you know what to look for. Listen to an old modem sound. That's what efficient data transmission sounds like. If there happen to be some interstellar radio beams that hit this planet occasionally, they might not be recognized easily.
Signals sent in a noisy environment have to contain some redundancy and synchronization information to be received successfully. So, unleash the machine learning algorithms on all that radio telescope data. Worth a try.
An observation about anything published: Why do the make me read the entire article to find what I want, which is a bulleted list of new techniques?
That's how most things I read online are. Many HN posts are long articles from which I'm trying to extract a bit of information. Who has time? If I want more context, I'll read it after I find out what the techniques are.
Maybe I can use an AI to do it for me: 'Please list the new techniques in this artcle'.
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[ 2.0 ms ] story [ 111 ms ] threadThis is one of the most interesting empirical questions, if there is life or not outside of us, but it seems like there must be.
And if there is extra terrestrial life, there are probably large clusters of it because of confounding reasons, like stable stars making it easier for multiple planets in system to be habitable, somewhere out there.
We probably know we are not close to a ‘large cluster’, because we’d know by now by the local nature of clusters.
So I think we can/should be in the headspace of the Foundation series. There are almost assuredly large clusters of power, and we are not part of it. The clusters know this state of affairs and so do all the outlier planets like us.
I’m not saying we should remain hidden or anything. I’m not even sure what the consequences are in this headspace. But I think we can and possibly should start realizing we’d be in contact by a cluster rapidly, if there were any in our Galaxy.
That dynamic just seems so inevitable and Asimov was able to capture it. The clusters will heavily cluster and remove most outliers by absorbing them. And the real outliers are very far between.
* https://en.wikipedia.org/wiki/Fermi_paradox
I don't buy that the problem is that we just don't know what to look for. There must be some observable characteristics that indicate its presence. It seems implausible that intelligent life forms would not leave any visible traces and that their planets would be indistinguishable from uninhabited ones.
I once looked into the reach of the Arecibo message; I can't quite remember the numbers but the main point stands: it's indecipherable but detectably artificial after a short distance (guess: 60-100 lightyears), and no longer distinguishable from natural radiation after about 5× that (guess: 250ish-600 lightyears).
The point is that even an intentional message quickly (in cosmic terms) becomes gibberish and, fairly soon after, too faded to even recognise as being a signal. On top of that, the receivers would have to be looking.
Basically, I doubt we would recognise artificial signals intentionally sent to us from further than 15 lightyears out except with much, much luck. That explains why we didn't find any clear non-intentional signals yet.
An interesting take on this is to flip the question: from how far away would we, with our current approaches, be able to unambiguously, definitively detect life on Earth? And intelligent life?
I'm not sure we're able to do even the former from Pluto, let alone from the interstellar medium.
We can communicate with Voyager 1 beyond the limits of the Solar System, so I am not sure if earth's constantly emitted signals would not be detectable from Jupiter.
The inverse square law tells you that the flux of a signal decreases at a square of the distance. A receiver 2 miles away from a transmitter will receive a signal at a quarter of the strength of a receiver only a mile away. Our broadband omnidirectional broadcasts don't actually reach very far out into the solar system let alone the galaxy. Only very powerful narrowband signals reach very far and those are very directional.
The Fermi paradox can be outmoded or not really relevant at these scales.
I avoided raising any particular outcomes other than the one thing which seems inevitable, the cluster-outlier dynamic. It’s weird this reasoning exists, or it was at least interesting to Asmiov imo. I think he found most interesting that a few distant inevitabilities can be known, and space-wise those relate to the cluster/very very few outliers.
And I’m pretty sure there were aliens (The M**). Asimov was both relying on human sociology and history AND taking that to the largest backdrop. Like only needing a slice (statistics, modeling, or selective deep-thinking even) of something deep gain to gain immense wisdom about the future. That was the most interesting thing about the character who set the whole story in motion at least imo. Even the initiating character, The M**, and counter forces could not disrupt the course…No planet perpetually hidden, no stopping perpetual clustering…(sorry for spoilers)
In another words, it’s possible that all intelligent life is more or less at the same level of development, and this creates a situation where we only discover each other at the same time
[0]: https://qz.com/emails/quartz-obsession/1482596/simultaneous-...
[1]: https://en.m.wikipedia.org/wiki/Convergent_evolution
That being said, our civilization got an enormous boon coming later in the history of the planet. Fossil fuels and the abundant energy economy would not be available without the right biologic circumstances (eg lignin metabolism developing late) and timing.
What is the common refrain? If the facts don't fit the theory, then the theory is wrong! Isn't that the core essence of science? Empiricism is a repudiation of Platonic a priori reasoning. Beautiful and elegant theories that don't fit the facts are simply wrong.
In the Robot novels, the overwhelming majority of humans live on Earth in mega cities (caves of steel) with relatively few robots, and a small minority of humans live on a few dozen (50 or so) other worlds in highly roboticized societies. These humans call themselves Spacers and have very xenophobic inward cultures. In the extreme cases, exemplified by Solaris, they shun contact even with other Spacers from their own planet and surround themselves entirely with robots.
Eventually the human majority leaves Earth, because a robot following the Zeroth Law decides to irradiate Earth to force humanity to spread out in the galaxy. The humans from Earth don't take many if any robots with them and rapidly overtake robot-centric Spacer culture, which is all but forgotten (as are robots). The massive galactic human population of the Empire novels are the descendants of the humans that left Earth later, not the Spacers.
* Maybe D. should have thought about that possibility before embarking on a scheme that required hindering humanity's technical development for an indefinite period?
N. B. It most closely resembles the part of Foundation where the Mule shows up.
Otherwise, I always found favour (regrettably) with the argument that the amount of energy needed to transmit a signal across the galaxy was too great, as the intensity of the signal falls by the cube of the distance.
Another idea of that seems to be trending in fiction for the last several decades, from the Culture series to the Three-Body Problem to Westworld, is the idea of the sublime, and the proposition that the so-called elder species would have transitioned and left our galaxy some time ago, hence why we haven’t seen any evidence for their existence. Could anyone also comment on this popular idea?
Basically, it seems to me that many, many conditions have to come together for life to emerge at all on a given planet, and then many, many more conditions have to develop for intelligent life to emerge. If the denominator in that probability is significantly larger than the number of planets in the galaxy, then the probability of any given galaxy harboring intelligent species would be approximately zero. Similarly, the conditional probability that there are at least two intelligent species in a galaxy given there is at least one (namely humans here on Earth) is still approximately zero.
I personally think there was civilized life long ago, but it died out fairly quickly, the same way ours might. Time and space are so vast that there can easily be million-year and trillion-mile gaps in between each attempt at life that gets far enough to meaningfully search for the existence of other life elsewhere.
Our universe is brutal and doesn't have any bias towards sentient life surviving. It does not care.
The vastness of space and time mean that there might have been millions of other civilizations that have reached our current level of technical advancement with no real overlap.
Now consider that advanced human life took a very long time to develop on Earth, even after multicellular life took off, which itself took a very long time to happen. Assuming that evolution inevitably converges onto something like humans is anthropocentric. It may be the case that life is reasonably common but intelligent life such as us is an absurdly rare fluke of luck.
I'd be surprised if life isn't fairly common, but wouldn't be surprised if complex life is very rare.
Like what?
> It's way more than just being the right size, the right distance from a not-too-dangerous star, and having water.
Besides that and having carbon (and nitrogen, I suppose), perhaps some small amounts of other elements, what are you referring to?
It doesn't get discussed enough how much of a factor blind stupid luck was in the one example we have of the evolution of intelligence in the universe.
What's to say that in the absence of the K-T event, some dominant dinosaur species wouldn't have eventually evolved their intelligence to our level? Perhaps even earlier?
It's not like the K-T event is a prerequisite for "general" intelligence, is it?
Perhaps in such an alternative universe where the K-T event didn't happen you'd be a dinosaur posting on Dinohacker News right now.
Given the relative quickness that intelligence exploded in later hominids, who knows. we could know about some gibbon analog in the dinosaurs right now, that given just a little longer could've made it to human levels of intelligence.
Carbonate-silicate cycle breaking is what's considered the most likely thing to end complex life on Earth, for instance. All it takes to cause that is the Sun getting slightly brighter. In a few hundred million years it'll become increasingly difficult (inefficient) for plants to photosynthesize, reducing energy available to the biosphere, until finally photosynthesis stops completely.
So you're saying that in such a scenario, it would be impossible for complex life to exist, even if it looks different from the complex life we have now?
I am just wondering whether we are not confusing "complex life as we've seen to exist" with "complex life that can possibly exist".
For example, I am wondering whether the Great Oxidation Event is not a counterexample where we had a run-away biological process that caused a mass extinction (which, if it were possible for us to be alive at the time, might have looked like it would be impossible to recover from) but still lead to complex life existing despite oxygen being so toxic (at least from the point of view of the kind of life that existed at the time).
I know this is not the best example, as at the time complex life didn't exist yet. But I'm wondering if it wouldn't have been possible for complex life to exist in an oxygen-poor environment. Well, in fact some multicellular species that exist today are anaerobic and therefore do thrive without oxygen, right? Perhaps such anaerobic life would have evolved a lot more if our atmosphere had never been oxygenated.
Unfortunately I know nothing about the examples you mentioned, so I can't tell whether they are comparable.
Edit: I just read a bit about the carbonate-silicate cycle and I think I know what you mean now. Yes, if surface temperatures were more extreme it would indeed be quite difficult for complex life to exist (at the surface, at least). After all, some limits to the existence of interesting life must surely exist and temperature does seem like an inherent one.
My point isn't that life can't exist otherwise (ocean vents exist—though, you do need an active core for that—and anaerobic life is a thing, as you point out) but that only certain routes, even assuming there are some wildly different paths that might work, will yield enough energy to support complex life. You need a system that's reasonably stable (i.e. tends to prevent a variety of runaway events, turning them into cycles instead) even when life itself is changing the environment. Sometimes life will step in to do that if you get lucky (as in the oxygenation crisis, which you mentioned) but the planet itself needs a bunch of stuff to be just right, too—not just conditions, but processes.
I suspect there are lots of planets with some bio-goo on them, maybe even quite a few with things as complex as some insects or crustaceans. I further suspect there are very few (perhaps about as close as one can get to "none" without reaching it) that could support something like (even for generous values of "like") our giant tree of vertebrates. Not enough energy available, or, there is, but the world lacks the processes to stop life's own effects from wrecking the environment and stunting its own potential.
Then there's the fact that even complex life doesn't seem to necessarily lead to advanced intelligence and civilization. I mean, look at how long it took humans to develop writing! All that other stuff had gone just right, and intelligence emerged, and we happened to be a tribal species (probably), but we still puttered around for, what, a few hundred thousand years? The dinosaurs had no space program, nor the birds, nor the whales, nor fish, despite existing for tens or hundreds of millions of years—intelligence and the right kind of cooperative pack/tribe behavior to let it flourish seems to be a really rare combo, even when everything else has worked out very well for complex life.
Furthermore, I don't even have any good counter-arguments (at least not any that wouldn't just be pure speculation).
You definitely gave me something new to think about.
Thank you for your thoughts!
Things like plate tectonics to periodically send material down to the mantle, pull fresh material back up, and pump all kinds of stuff into the atmosphere, are really important for maintaining long-term stability. Imagine how much less life the oceans could support without rivers dumping disolved nutrients into them all the time—and those rivers have nutrients to dump, even billions of years into our planet's history, because of plate tectonics, because there's a water cycle at all, et c.
There are other filters, too. Hard for an aquatic intelligent species to kick-start civilization—how will they get started using fire? One can come up with ways, maybe, kinda, but would they stumble on those methods the way we stumbled on fire, almost effortlessly (then still took many millennia to discover how to do much more with it than burn forests/grasslands, cook food, excavate shallow caves, and harden wooden points)? For some high-clouds ecosystems (as some speculate may exist) on planets that can't support (much) life at ground level... how would an intelligent species there build anything? The only materials available would be parts of other high-altitude life forms. That's assuming you could get enough biomass up there to supply the kind of readily-available energy and nutrients an active, complex, smart life-form needs to be able to gather from its environment in the first place. That sort of thing. Plus you're counting on the emergence of physical features necessary for tool use at all (like our hands) which is something that pretty much only climbing species develop, as a side-effect of needing to grip things all the time.
I think there are lots of things working against the emergence of not just complex life, not just intelligent life, but coordinated civilizations with long-term retention and transmission of knowledge that can accomplish things we might associate with advanced alien life forms. Even if life turns out to be very common, I expect complex life is not, intelligent life even less so, and civilization vanishingly rare. But, again, I could be wrong—it's all guesswork, really.
Honestly, I don't think we have nearly enough information to be able to put much confidence in our ability to calculate a meaningful probability of life currently. Drake's Equation is fine, but without any way to validate the coefficients, you can make it say anything you want.
There are Prof Kippling’s arguments.
Why we might be alone
https://youtu.be/zcInt58juL4
Bayesian analysis of existence of intelligent life
https://youtu.be/iLbbpRYRW5Y
And yet civilisation has only existed (that we know) for the last few thousand years.
It seems that it might take a long time for complex life to establish itself.
Brian Cox touches on this here https://youtu.be/aPOCP4GHJvI at around the 7:00 mark.
Sending some EM signal and hoping for an answer appears somewhat ridiculus. If at all possible, you would go yourself or send an AI capable of doing some serious information gathering.
Now, why do people pretend, the time of travel was prohibitive? Not only does that rely on the weirdly self-centered assumption, substantial speeds weren't accessible, it also presupposes domestic time frames.
Lastly, the idea we should have been "visited" already. This has the unspoken implication of some big vehicle appearing in the sky, radio broadcasts and TV crews gathering, etc. Why? What sane entity would go about it in this manner?
It’s that basically what happened in our planets ‘Age of Discovery’? Some European ship shows up on a shore/lagoon and ‘takes over’?
https://www.pbs.org/gunsgermssteel/variables/smallpox.html
There are rather understandable limitations on the physical size of electromagnetic transmitters due to wavelength and power parameters. There are also size limitations for sensors: you cannot capture too few photons per second, else you will not register a coherent picture of faster-moving processes on Earth.
There are also limitations on the size and mass of a device that needs to slow down from interstellar speeds to take a reasonable peek at Earth.
Basically, physics as currently known to us does not allow for a grain-sized interstellar sounding craft that could transmit back much useful info, let alone to spread a lifeform.
SETI used to be focused on looking for RF carriers. Few modulation modes still in use waste energy in the carrier signal. In newer modes, a small amount of redundancy in the bit pattern provides synchronization. Analog TV was 80% carrier, 20% content at megawatt levels, probably the most detectable signal ever sent from this planet. Hugely redundant and easy to decode. But now it's history. This planet emitted high-powered carriers for less than a century.
Modern RF signals look like noise unless you know what to look for. Listen to an old modem sound. That's what efficient data transmission sounds like. If there happen to be some interstellar radio beams that hit this planet occasionally, they might not be recognized easily.
Signals sent in a noisy environment have to contain some redundancy and synchronization information to be received successfully. So, unleash the machine learning algorithms on all that radio telescope data. Worth a try.
That's how most things I read online are. Many HN posts are long articles from which I'm trying to extract a bit of information. Who has time? If I want more context, I'll read it after I find out what the techniques are.
Maybe I can use an AI to do it for me: 'Please list the new techniques in this artcle'.