15 ms·

If Loud Aliens Explain Human Earliness, Quiet Aliens Are Also Rare

79 points by Borrible 5y ago

arbitrage 5y ago
> We estimate that loud alien civilizations now control 40-50% of universe volume, each will later control ~10^5 - 3x10^7 galaxies, and we could meet them in ~200Myr - 2Gyr. This is utter nonsense.
- Reason077 5y ago
  Feel free to post your own estimate. Please include your reasoning.
  - h2odragon 5y ago
    The estimates here are as good as anyone can make, I think. Of course we can choose our postulates and come to any conclusion we want, as they have done here. When we've only really got conjecture and guess and golly to work with, it's all going to be a bit of an exersize in intellectual masturbation. Quibbles about methodology are just comparing techniques: long v short stroke, with or without twist, etc. The input and the output is still the same and of the same value.
  - dogma1138 5y ago
    You don’t need your own estimates to call BS on theirs. Including simply on the premise of the volume of the universe, most of the universe is an empty void. Even if you allow somehow for the traversal of intergalactic void in your local clusters this alone should put a much more serious dampening effect on the expansion of any given species. It also assumes that species can even get to the technological level required for galactic and then intergalactic expansion and maintain that level pretty much indefinitely. But then again this isn’t a research paper or even a particularly serious statement.
    - jefftk 5y ago
      > this isn’t a research paper It's the host organization's announcement for https://arxiv.org/pdf/2102.01522.pdf https://arxiv.org/pdf/2102.01522.pdf
    - datavirtue 5y ago
      You need energy mastery. Ability to harness infinite or practically infinite energy available freely. With this understanding and power you can innovate further, perhaps gaining the ability to create matter and one day transport it along the fabric of space outside the constraints of existing matter (time). Then again, maybe true advancement means losing interest in manipulating matter, turning inward and finding or developing enhanced mental states that let us see things clearly without understanding everything empirically. Perhaps the ultimate goal is to be at peace and even joyful at living and dying. Humans are still very believe-y, angry, outward and confused.
      - dogma1138 5y ago
        If you attain that level of technology why do you need to go anywhere? If you gain access to infinite or near infinite energy source it seems like it would be a waste to use that energy to cross the intergalactic void or even outside your solar system or star cluster since you could simply use it to build w/e you need anywhere in space so you might as well stay put.
        thevardanian 5y ago
        Resilience. Being multi-planetary means your species is fundamentally protected from almost all catastrophic events. Having presence among multiple stars systems would mean not even planetary level destruction would be a threat to a species. As it currently stands humans are still very much in a precarious situation as an errant asteroid, even a decade away, could mean game over for all of humanity.
        dogma1138 5y ago
        You missed my point, if you can attain that level of technology you don’t really care about your planet at that point either. The amount of energy required for to cross the intergalactic void is insane. Our local group is about 3 megaparsecs in diameter the Milky Way is around 32 kiloparsecs in diameter. Asteroids aren’t a problem if you can expand to other solar systems yet alone across galaxies.
- VortexDream 5y ago
  In what way is it nonsense?
  - icapybara 5y ago
    Extraordinary claims require extraordinary evidence. This statement, with absolutely no hard evidence, is asserting that aliens exist and in fact control 40-50% of the universe. Furthermore it is also fundamentally untestable as it includes the convenient disclaimer that "we will meet them in 200 Myr - 2 Gyr." "I have never seen a unicorn nor do I have any evidence they exist. However, their existence seems logical, and therefore I estimate that they control 40-50% of the universe volume, each will control ~10^5 - 3x10^7 galaxies, and we could meet them in ~200 Myr - 2 Gyr."
    - nathanmcrae 5y ago
      The preceding sentences explain the model that generates that estimate, including the 200 Myr - 2 Gyr number; that's not a case of hand-waving. Is your issue with some aspects of the model or with the idea of trying to model this at all? It's certainly early days for this theory, but it's worth not dismissing out-of-hand.
      - icapybara 5y ago
        My issue is: can this model make testable predictions within our lifetimes? It doesn’t seem that way. Even models of the far future and the distance past of the universe are held to standards of evidence and testability. Why shouldn’t this one be?
        nathanmcrae 5y ago
        Yeah, that's an important point, but that seems to be an issue with the subject of study rather than this particular theory. At least their model has very concrete and explicit premises that could be used to reject it. Particularly the 'hard steps' model of evolution: I don't know how widely accepted that is (genuinely don't, it may be accepted) and, if it is in time rejected by the scientific community then that would discredit--if not falsify--the theory.
Gravityloss 5y ago
Interesting points, though the abstract is quite hard to follow. I guess it makes sense: 1. aliens spread at a certain speed after developing spaceflight 2. they're not here 3. there are no spacefaring aliens in the galaxy currently
- AutumnCurtain 5y ago
  I felt like I could have used a better articulation of their definition of "loud" and "quiet" aliens, unless these are well known terms in the domain terms and I am just unfamiliar...
  - mannykannot 5y ago
    The abstracts of papers are intentionally terse, which usually means they are addressed to people already familiar with the field. The paper itself is often more readable (though by no means always!) and it is often worth taking a look at the introduction and conclusion, at least. Here, we have 'To a first approximation, there are two kinds of aliens: quiet and loud. Loud (or “expansive”) aliens expand fast, last long, and make visible changes to their volumes. Quiet aliens fail to meet at least one of these criteria.'
  - deleted 5y ago
    [deleted]
- 7thaccount 5y ago
  The Fermi Paradox (where is everyone) has been debated for decades. There are so many possibilities such as great filters (early or late), prime directive, zoo hypothesis, dark forest hypothesis...etc etc. I'm sure you're aware of this, but I included just in case you wanted to explore in more depth. Some really good stuff.
  - AtlasBarfed 5y ago
    I just heard about the dark forest a couple weeks ago. I believe it to be the model we should proceed with for safety. Assuming FTL isn't possible, the fact that dark energy makes large sections of the visible universe fundamentally inaccessible is probably a good thing. Otherwise that is a lot more of the universe that may be ahead of us and would stomp us like ants.
candiodari 5y ago
If you look at the realistic reach of the signals of human civilization, it's a few tens of lightyears at best. And once you factor in how inhumane it'd be to send children out to colonize foreign solar systems ... are we really sure we'll do that? That's 10 generations that live their entire lives in small metal boxes ... without the vast majority of everything we have on earth. Not so much as a single field of grass (or field of anything, building a big room in space will be a great challenge, especially since weightlessness means you don't really need room). 10 generations that will have absolutely zero power to do anything about their situation. It will take 100+ generations before anything remotely resembling earth level comfort will happen (assuming the planets encountered can at any point support human life. If they need to be terraformed, we're easily talking 1000+ generations)
- dogma1138 5y ago
  That’s an accurate statement the reality is that any civilization that develops sufficient level of technology to allow it to spread across a single galaxy or even to adjacent star systems would be able to use that technology to find better alternatives in their own star system. That’s if civilizations even live that long in the first place.
  - Ekaros 5y ago
    Minimal fraction of suns energy output would allow insane number of humans to survive. And it will be around a while so there is really no hurry to move out. Kinda comes to calculation that when earliest potentially space faring civilisation runs out of their sun? And can't adapt to live in system. For us that would still be at least few billions of years if not more with proper preparation.
    - Nbox9 5y ago
      I could imagine humans fighting over the limited energy harvested by Sol’s Dyson sphere in 10million years. It would give any group of human’s controlling it a massive advantage, similarly to the advantage having the only A-bomb gave US briefly.
whyAstate 5y ago
What if aliens nearly exhausted their home planet resources and scaled back industrial life? Perhaps too many technical missteps, social unrest, meant they’ve linearly creeped along making no technological leaps, but still providing a decent life to each other, until so much time went by, they realized too late about the possibility of space travel? This is always feels like humans looking for our doppelgängers to sell a sensational concept.
jefftk 5y ago
Full paper: https://arxiv.org/pdf/2102.01522.pdf https://arxiv.org/pdf/2102.01522.pdf
- est31 5y ago
  HTML version: https://www.arxiv-vanity.com/papers/2102.01522/ https://www.arxiv-vanity.com/papers/2102.01522/
cletus 5y ago
Given these two constraints: 1. The speed of light is a hard speed limit. This means there's also no cheating with warp drives, other forms of FTL, crossing dimensions, parallel universes or time travel; and 2. The laws of thermodynamics as we understand them hold true. then the outcome of spacefaring civilization I believe is generally inevitable. That is, the ultimately limiting factor is energy and mass. The easiest way to get both is with Dyson Swarms. This requires no new physics and no exotic materials. If so, then a galaxy-spanning civilization is going to be completely obvious from a million light years away from the spectrum. Why? Because a full Dyson Swarm would have a very unique spectrum, specifically very little visible light and a lot of IR. That's just basic physics. The only realistic way to get rid of heat in space is to radiate it away and the wavelength of that is a function of temperature. This is discussed in the context of the Fermi Paradox, which has the advantage that you don't need to determine what every alien civilization does, you just need to know if there are any exceptions. Example: if there were 1000 spacefaring civilizations in the Milky Way, what are the odds that all 1000 of them (assuming they were within out light cone) would remain quiet or hidden? Couple that with mass and energy ultimately being limited then there is a strong incentive and advantage in becoming as large as possible. So even if 99% of civilizations remain quiet, the 1% will still make themselves visible. Additionally, on the notion of hidden civilizations in particular, it's essentially impossible to remain hidden to a K2 or K3 civilization so there's really no point. This is what gives me confidence that the Milky Way isn't teeming with spacefaring life. In fact I consider it much more likely we're the only such civilization in the Milky Way (within our light cone).
- mattmanser 5y ago
  Seems like a good theory, but when I read something like this it always makes me think about any of the sci-fi I've read that was written 50-75 years ago. They're also full of what were at the time good theories, but that are now so wrong it often makes reading the story difficult, even with my fairly rudimentary modern astrophysics knowledge. In all honesty I think it's more likely any sufficiently advanced civilization capable of interstellar travel has probably descended entirely into virtual reality or a singularity. I mean, what would you prefer? Being the star of your own personal VR space, the next Malcolm Reynolds, space cowboying around where you are the entire focus of that reality. Or schlepping it over to another star in a generation ship or whatever where even if you were somehow still alive when it arrived, you'd be landing on a planet that will probably instantly kill you.
deleted 5y ago
[deleted]
RupertEisenhart 5y ago
For more background and related material, look at Hansons blog[0] or the dedicated website[1]. [0]: https://www.overcomingbias.com/?s=aliens https://www.overcomingbias.com/?s=aliens [1]: https://grabbyaliens.com/ https://grabbyaliens.com/
seph-reed 5y ago
I remember seeing somewhere that witnessing the cosmic radiation of the big bang is something we have a fairly lucky time-slot to be able to do. If that's the case, and we're early to the universe, it seems like the kind of data we should try to make sure survives beyond us.
- bserge 5y ago
  Maybe someone did write "Don't be a cunt" using a bunch of stars and we just can't read it :D
- merpnderp 5y ago
  Talk about lucky, the Earth will only be habitable by most life for another 500 million years. We showed up in the last 10% of Earth's (habitable) life. If evolution would have zigged instead zagging, we'd never have been at all.
  - Reason077 5y ago
    > ”We showed up in the last 10% of Earth's (habitable) life.” While the Earth has hosted microbial life for about 3.7 billion years, it was only about 2.3 billion years ago (the GOE) that free oxygen started to accumulate in the ocean and atmosphere, making complex multicellular life possible. So we’re probably in more like the last 20% or 25% of the habitable period.
- jandrese 5y ago
  It doesn't seem all that likely that we're just too early. The planet was stuck with dinosaurs for hundreds of millions of years.
  - betwixthewires 5y ago
    Well paradoxically, it having taken so long for us might mean that it simply takes a long time, which would imply that we are, in fact, early. The truth is though that we just don't know. I think we are early.
mFixman 5y ago
I never understood these kind of analyses that talk about aliens reaching "humanity’s level" like it's inevitable or somehow special. We could blast radio waves with ABBA songs into space to find whether there are other Swedish-speaking civilizations, or whether we are alone in the Universe. We don't because it's silly to think of the Swedish language as a necessary step for "advanced life". Why do we think that human-like intelligence is special?
- astroalex 5y ago
  This seems a bit backwards to me. It's only futile to blast ABBA songs (or other human-like signals) into space if we think human-like intelligence is special. It's precisely because we believe human-like intelligence is _not_ special that blasting (or listening for) space signals makes any sense. The assumption is that other civilizations will converge on some of the same technology that we've developed and recognize a patterned signal when they see one.
  - mFixman 5y ago
    > The assumption is that other civilizations will converge on some of the same technology that we've developed and recognize a patterned signal when they see one. Why would anyone think that? No other species in the history of the Earth has the ability to create human languages. Nobody outside the tiny group of 0.1% of humanity can speak Swedish. No single rock we've observed outside our planet can even understand the concept of a word like "Läderlappen" or "Knullruffs". Those 10 million people are alone in the Universe as developers and speakers of Swedish just like these 7.9 billion people are alone in the Universe as developers and users of human-like intelligence. Blasting signals into space is the same as singing ABBA songs really loud: maybe a sci-fi civilization of Klingons who speak a Swedish-like language could understand it, but in our Universe there's no chance that some extraterrestrial thing will converge on the same languages or technologies as we did.
    - T-A 5y ago
      Radio is currently the only realistic means of interstellar communication at our disposal, so we listen for (and sometimes send [1]) radio waves. In other words, we look for aliens equipped with radio telescopes, because they are the only kind we can hope to find. The choice of language follows from that. To have technology at the level of radio telescopes, you need to understand physics at mid-20th century level (or higher). To understand physics at that level, you need math at the level of calculus and differential equations. So we look for, and sometimes send, messages which start with simple mathematical relations and then build up to physical quantities. [1] https://en.wikipedia.org/wiki/Arecibo_message https://en.wikipedia.org/wiki/Arecibo_message
titzer 5y ago
I find these kinds of analyses to be hopelessly oversimplified. First of all, we are talking about predicting the actions of superintelligent aliens. We aren't talking about slime molds or a bacterial infection, but beings with more intelligence than us, like orders of magnitude more complicated reasoning processes. They are effectively unpredictable, because if they weren't, wouldn't we be just as smart as they are? That level of intelligence comes with new levels of reflectiveness that are frankly not accessible to our weak brains. Like, maybe after reaching the next level of enlightenment, they decide that expansion throughout the universe like a worm is not actually what they want or that is what is good for the universe? Maybe they decide to rather study the universe and not interfere, the way biologists study, say, apes, without wanting to disrupt their natural behavior with their presence? Or maybe superintelligent beings find a way out of our universe, and pass into another dimension (cyberspace? black holes? disappearing through quantum foam? heaven?). Or maybe something else insane happens, like being superintelligent inevitably makes you completely terrified of everything, because you realize how powerful other aliens are and your calculations unequivocally show it's safer to stay at home and fart around doing the super-intelligent analog of baking chocolate-chip cookies? Not being superintelligent, we are like ants trying to contemplate human civilization. We have no context or experience, and we simply don't have the mental capacity to even imagine what we don't know. Second, these probabilistic models are so fundamentally stupid. It's impossible for us to reliably estimate the probability of any event that's happened only once (without reasoning about the process that gave rise to that event), as we cannot estimate posterior probabilities without lots of samples. And humans on Earth have a massive chain of single-occurrence events that all seem to be absurdly improbable. Besides that, and perhaps even because of that, it's not even a foregone conclusion that our universe even selects from the middle of the distribution (i.e. is not biased). We could perfectly estimate the shape of a probability curve and yet live in a universe that stubbornly selects from the end of the distribution, all the time. All of our math could be totally right, but crazy shit just keeps happening. Third, the anthropic principle is a total bitch. It means that we will never be able to estimate probabilities of events that were required to create us, because no matter how improbable they were, if they didn't happen, we're not even here to argue about it. If there are infinite universes (a multiverse, see Tegmark), then forget this whole mathematical sophistry, because then there is no need to live in some "average" universe; we can easily live in some stupidly improbably snowflake universe that has the 90 trillion improbable things that make apes possible; infinity doesn't care.
matchagaucho 5y ago
> Which seems bad news for SETI. SETI conceded many years ago that the evidence of a "Loud" alien species > a few Million years ago might be virtually undetectable today.
groby_b 5y ago
"If we assume that our knowledge is the pinnacle of knowledge, we are the first to reach it" is a bit tautological, no? You can apply a very similar reasoning to an isolated tribe stuck at, say, stone-age level on a remote island. With barely seaworthy canoes. They very likely have no idea we exist, and their assumption will be that if there were better canoes, and people had them, they would've made contact. So clearly, they must be among the first. I am continually amused by the gyrations we go through to avoid saying "we don't know". I mean, last I checked we couldn't even account for 85% of the matter in the universe that should exist according to the laws of physics as we know them. If we can't even find the vast majority of matter, why do we think we'd do better with civilizations?
deleted 5y ago
[deleted]
aaroninsf 5y ago
Observations or assumptions about the presence or prevalence of life which take as a premise that we could detect them are IMO meaningless. In particular, work like this makes assumptions about what it means to be "loud" which contain what amounts IMO to a profoundly inane belief that advanced civilizations would employ communications that are similar enough to our own that we could detect them, or, would leak energy in a fashion we could detect. Both of these premises are deeply anthropocentric, in specific, they extrapolate from our current and 20th c. level technologies and understanding of physics, material science, etc., not even touching on philosophical matters like the dark forest hypothesis, which are so myopic as to be comical. Idle comment, sometime in the last year or so there was a detailed write up of a zero-day no-touch exploit for the iPhone, which included a nice tour through the wireless stacks and hacks Apple uses to do things like proximal device detection and networking. What struck me at the time and continues to inform my opinion on these SETI questions is, without the frame for understanding the why- and how- going on in the iPhone, the scale of effort it would take a naive investigator to build a basic model of what was going on and why, is already at the threshold of human comprehension. While in this specific case what's at issue is EMF using crudely comparable encoding schemes, the point is simply that even knowing about various obvious ways of encoding binary information for transmission in a noisy environment, the active signal(s) are already close to the edge of discernible from noise, especially complex but true noise. I.e., even in the EMF domain, we're already for fungible consumer goods dealing with multiple frequency-hopping handshakes and sniffs and stochastic back-off and retry and error correction. But there is no good reason to assume some other civilization at some other level of advancement would have any use for EMF. There are even with known technologies all sorts of exotic, more efficient, more targeted, ways of doing long-distance communication. Helically polarized lasers come to mind... Anyway. I think the authors of these things need to be a lot more humble about their presumptions, or at minimum, spell them out plainly...
fallingfrog 5y ago
One issue here is that there’s no economic reason for the home planet to mount the sort of resources it would take to fund an interstellar trip. Stars are farther away than you think. The only way I can see that it would happen is for religious reasons, if the belief system of the religion required them to do it. Because there’s no economic reason. The other issue is that it’s not clear how long technological civilizations last. We might be close to exhausting our own planet just 150 years after the invention of radio. Maybe technological civilizations bloom in the dark like beautiful flowers, then burn out quickly before they can spread to other systems.

79 points by Borrible 5y ago

> We estimate that loud alien civilizations now control 40-50% of universe volume, each will later control ~10^5 - 3x10^7 galaxies, and we could meet them in ~200Myr - 2Gyr. This is utter nonsense.

Reason077 5y ago
Feel free to post your own estimate. Please include your reasoning.
- h2odragon 5y ago
  The estimates here are as good as anyone can make, I think. Of course we can choose our postulates and come to any conclusion we want, as they have done here. When we've only really got conjecture and guess and golly to work with, it's all going to be a bit of an exersize in intellectual masturbation. Quibbles about methodology are just comparing techniques: long v short stroke, with or without twist, etc. The input and the output is still the same and of the same value.
- dogma1138 5y ago
  You don’t need your own estimates to call BS on theirs. Including simply on the premise of the volume of the universe, most of the universe is an empty void. Even if you allow somehow for the traversal of intergalactic void in your local clusters this alone should put a much more serious dampening effect on the expansion of any given species. It also assumes that species can even get to the technological level required for galactic and then intergalactic expansion and maintain that level pretty much indefinitely. But then again this isn’t a research paper or even a particularly serious statement.
  - jefftk 5y ago
    > this isn’t a research paper It's the host organization's announcement for https://arxiv.org/pdf/2102.01522.pdf https://arxiv.org/pdf/2102.01522.pdf
  - datavirtue 5y ago
    You need energy mastery. Ability to harness infinite or practically infinite energy available freely. With this understanding and power you can innovate further, perhaps gaining the ability to create matter and one day transport it along the fabric of space outside the constraints of existing matter (time). Then again, maybe true advancement means losing interest in manipulating matter, turning inward and finding or developing enhanced mental states that let us see things clearly without understanding everything empirically. Perhaps the ultimate goal is to be at peace and even joyful at living and dying. Humans are still very believe-y, angry, outward and confused.
    - dogma1138 5y ago
      If you attain that level of technology why do you need to go anywhere? If you gain access to infinite or near infinite energy source it seems like it would be a waste to use that energy to cross the intergalactic void or even outside your solar system or star cluster since you could simply use it to build w/e you need anywhere in space so you might as well stay put.
      - thevardanian 5y ago
        Resilience. Being multi-planetary means your species is fundamentally protected from almost all catastrophic events. Having presence among multiple stars systems would mean not even planetary level destruction would be a threat to a species. As it currently stands humans are still very much in a precarious situation as an errant asteroid, even a decade away, could mean game over for all of humanity.
        dogma1138 5y ago
        You missed my point, if you can attain that level of technology you don’t really care about your planet at that point either. The amount of energy required for to cross the intergalactic void is insane. Our local group is about 3 megaparsecs in diameter the Milky Way is around 32 kiloparsecs in diameter. Asteroids aren’t a problem if you can expand to other solar systems yet alone across galaxies.
VortexDream 5y ago
In what way is it nonsense?
- icapybara 5y ago
  Extraordinary claims require extraordinary evidence. This statement, with absolutely no hard evidence, is asserting that aliens exist and in fact control 40-50% of the universe. Furthermore it is also fundamentally untestable as it includes the convenient disclaimer that "we will meet them in 200 Myr - 2 Gyr." "I have never seen a unicorn nor do I have any evidence they exist. However, their existence seems logical, and therefore I estimate that they control 40-50% of the universe volume, each will control ~10^5 - 3x10^7 galaxies, and we could meet them in ~200 Myr - 2 Gyr."
  - nathanmcrae 5y ago
    The preceding sentences explain the model that generates that estimate, including the 200 Myr - 2 Gyr number; that's not a case of hand-waving. Is your issue with some aspects of the model or with the idea of trying to model this at all? It's certainly early days for this theory, but it's worth not dismissing out-of-hand.
    - icapybara 5y ago
      My issue is: can this model make testable predictions within our lifetimes? It doesn’t seem that way. Even models of the far future and the distance past of the universe are held to standards of evidence and testability. Why shouldn’t this one be?
      - nathanmcrae 5y ago
        Yeah, that's an important point, but that seems to be an issue with the subject of study rather than this particular theory. At least their model has very concrete and explicit premises that could be used to reject it. Particularly the 'hard steps' model of evolution: I don't know how widely accepted that is (genuinely don't, it may be accepted) and, if it is in time rejected by the scientific community then that would discredit--if not falsify--the theory.

Gravityloss 5y ago

Interesting points, though the abstract is quite hard to follow. I guess it makes sense: 1. aliens spread at a certain speed after developing spaceflight 2. they're not here 3. there are no spacefaring aliens in the galaxy currently

AutumnCurtain 5y ago
I felt like I could have used a better articulation of their definition of "loud" and "quiet" aliens, unless these are well known terms in the domain terms and I am just unfamiliar...
- mannykannot 5y ago
  The abstracts of papers are intentionally terse, which usually means they are addressed to people already familiar with the field. The paper itself is often more readable (though by no means always!) and it is often worth taking a look at the introduction and conclusion, at least. Here, we have 'To a first approximation, there are two kinds of aliens: quiet and loud. Loud (or “expansive”) aliens expand fast, last long, and make visible changes to their volumes. Quiet aliens fail to meet at least one of these criteria.'
- deleted 5y ago
  [deleted]
7thaccount 5y ago
The Fermi Paradox (where is everyone) has been debated for decades. There are so many possibilities such as great filters (early or late), prime directive, zoo hypothesis, dark forest hypothesis...etc etc. I'm sure you're aware of this, but I included just in case you wanted to explore in more depth. Some really good stuff.
- AtlasBarfed 5y ago
  I just heard about the dark forest a couple weeks ago. I believe it to be the model we should proceed with for safety. Assuming FTL isn't possible, the fact that dark energy makes large sections of the visible universe fundamentally inaccessible is probably a good thing. Otherwise that is a lot more of the universe that may be ahead of us and would stomp us like ants.

candiodari 5y ago

If you look at the realistic reach of the signals of human civilization, it's a few tens of lightyears at best. And once you factor in how inhumane it'd be to send children out to colonize foreign solar systems ... are we really sure we'll do that? That's 10 generations that live their entire lives in small metal boxes ... without the vast majority of everything we have on earth. Not so much as a single field of grass (or field of anything, building a big room in space will be a great challenge, especially since weightlessness means you don't really need room). 10 generations that will have absolutely zero power to do anything about their situation. It will take 100+ generations before anything remotely resembling earth level comfort will happen (assuming the planets encountered can at any point support human life. If they need to be terraformed, we're easily talking 1000+ generations)

dogma1138 5y ago
That’s an accurate statement the reality is that any civilization that develops sufficient level of technology to allow it to spread across a single galaxy or even to adjacent star systems would be able to use that technology to find better alternatives in their own star system. That’s if civilizations even live that long in the first place.
- Ekaros 5y ago
  Minimal fraction of suns energy output would allow insane number of humans to survive. And it will be around a while so there is really no hurry to move out. Kinda comes to calculation that when earliest potentially space faring civilisation runs out of their sun? And can't adapt to live in system. For us that would still be at least few billions of years if not more with proper preparation.
  - Nbox9 5y ago
    I could imagine humans fighting over the limited energy harvested by Sol’s Dyson sphere in 10million years. It would give any group of human’s controlling it a massive advantage, similarly to the advantage having the only A-bomb gave US briefly.

whyAstate 5y ago

What if aliens nearly exhausted their home planet resources and scaled back industrial life? Perhaps too many technical missteps, social unrest, meant they’ve linearly creeped along making no technological leaps, but still providing a decent life to each other, until so much time went by, they realized too late about the possibility of space travel? This is always feels like humans looking for our doppelgängers to sell a sensational concept.

jefftk 5y ago

Full paper: https://arxiv.org/pdf/2102.01522.pdf https://arxiv.org/pdf/2102.01522.pdf

est31 5y ago
HTML version: https://www.arxiv-vanity.com/papers/2102.01522/ https://www.arxiv-vanity.com/papers/2102.01522/

cletus 5y ago

Given these two constraints: 1. The speed of light is a hard speed limit. This means there's also no cheating with warp drives, other forms of FTL, crossing dimensions, parallel universes or time travel; and 2. The laws of thermodynamics as we understand them hold true. then the outcome of spacefaring civilization I believe is generally inevitable. That is, the ultimately limiting factor is energy and mass. The easiest way to get both is with Dyson Swarms. This requires no new physics and no exotic materials. If so, then a galaxy-spanning civilization is going to be completely obvious from a million light years away from the spectrum. Why? Because a full Dyson Swarm would have a very unique spectrum, specifically very little visible light and a lot of IR. That's just basic physics. The only realistic way to get rid of heat in space is to radiate it away and the wavelength of that is a function of temperature. This is discussed in the context of the Fermi Paradox, which has the advantage that you don't need to determine what every alien civilization does, you just need to know if there are any exceptions. Example: if there were 1000 spacefaring civilizations in the Milky Way, what are the odds that all 1000 of them (assuming they were within out light cone) would remain quiet or hidden? Couple that with mass and energy ultimately being limited then there is a strong incentive and advantage in becoming as large as possible. So even if 99% of civilizations remain quiet, the 1% will still make themselves visible. Additionally, on the notion of hidden civilizations in particular, it's essentially impossible to remain hidden to a K2 or K3 civilization so there's really no point. This is what gives me confidence that the Milky Way isn't teeming with spacefaring life. In fact I consider it much more likely we're the only such civilization in the Milky Way (within our light cone).

mattmanser 5y ago
Seems like a good theory, but when I read something like this it always makes me think about any of the sci-fi I've read that was written 50-75 years ago. They're also full of what were at the time good theories, but that are now so wrong it often makes reading the story difficult, even with my fairly rudimentary modern astrophysics knowledge. In all honesty I think it's more likely any sufficiently advanced civilization capable of interstellar travel has probably descended entirely into virtual reality or a singularity. I mean, what would you prefer? Being the star of your own personal VR space, the next Malcolm Reynolds, space cowboying around where you are the entire focus of that reality. Or schlepping it over to another star in a generation ship or whatever where even if you were somehow still alive when it arrived, you'd be landing on a planet that will probably instantly kill you.

deleted 5y ago

[deleted]

RupertEisenhart 5y ago

For more background and related material, look at Hansons blog[0] or the dedicated website[1]. [0]: https://www.overcomingbias.com/?s=aliens https://www.overcomingbias.com/?s=aliens [1]: https://grabbyaliens.com/ https://grabbyaliens.com/

seph-reed 5y ago

I remember seeing somewhere that witnessing the cosmic radiation of the big bang is something we have a fairly lucky time-slot to be able to do. If that's the case, and we're early to the universe, it seems like the kind of data we should try to make sure survives beyond us.

bserge 5y ago
Maybe someone did write "Don't be a cunt" using a bunch of stars and we just can't read it :D
merpnderp 5y ago
Talk about lucky, the Earth will only be habitable by most life for another 500 million years. We showed up in the last 10% of Earth's (habitable) life. If evolution would have zigged instead zagging, we'd never have been at all.
- Reason077 5y ago
  > ”We showed up in the last 10% of Earth's (habitable) life.” While the Earth has hosted microbial life for about 3.7 billion years, it was only about 2.3 billion years ago (the GOE) that free oxygen started to accumulate in the ocean and atmosphere, making complex multicellular life possible. So we’re probably in more like the last 20% or 25% of the habitable period.
jandrese 5y ago
It doesn't seem all that likely that we're just too early. The planet was stuck with dinosaurs for hundreds of millions of years.
- betwixthewires 5y ago
  Well paradoxically, it having taken so long for us might mean that it simply takes a long time, which would imply that we are, in fact, early. The truth is though that we just don't know. I think we are early.

mFixman 5y ago

I never understood these kind of analyses that talk about aliens reaching "humanity’s level" like it's inevitable or somehow special. We could blast radio waves with ABBA songs into space to find whether there are other Swedish-speaking civilizations, or whether we are alone in the Universe. We don't because it's silly to think of the Swedish language as a necessary step for "advanced life". Why do we think that human-like intelligence is special?

astroalex 5y ago
This seems a bit backwards to me. It's only futile to blast ABBA songs (or other human-like signals) into space if we think human-like intelligence is special. It's precisely because we believe human-like intelligence is _not_ special that blasting (or listening for) space signals makes any sense. The assumption is that other civilizations will converge on some of the same technology that we've developed and recognize a patterned signal when they see one.
- mFixman 5y ago
  > The assumption is that other civilizations will converge on some of the same technology that we've developed and recognize a patterned signal when they see one. Why would anyone think that? No other species in the history of the Earth has the ability to create human languages. Nobody outside the tiny group of 0.1% of humanity can speak Swedish. No single rock we've observed outside our planet can even understand the concept of a word like "Läderlappen" or "Knullruffs". Those 10 million people are alone in the Universe as developers and speakers of Swedish just like these 7.9 billion people are alone in the Universe as developers and users of human-like intelligence. Blasting signals into space is the same as singing ABBA songs really loud: maybe a sci-fi civilization of Klingons who speak a Swedish-like language could understand it, but in our Universe there's no chance that some extraterrestrial thing will converge on the same languages or technologies as we did.
  - T-A 5y ago
    Radio is currently the only realistic means of interstellar communication at our disposal, so we listen for (and sometimes send [1]) radio waves. In other words, we look for aliens equipped with radio telescopes, because they are the only kind we can hope to find. The choice of language follows from that. To have technology at the level of radio telescopes, you need to understand physics at mid-20th century level (or higher). To understand physics at that level, you need math at the level of calculus and differential equations. So we look for, and sometimes send, messages which start with simple mathematical relations and then build up to physical quantities. [1] https://en.wikipedia.org/wiki/Arecibo_message https://en.wikipedia.org/wiki/Arecibo_message

titzer 5y ago

I find these kinds of analyses to be hopelessly oversimplified. First of all, we are talking about predicting the actions of superintelligent aliens. We aren't talking about slime molds or a bacterial infection, but beings with more intelligence than us, like orders of magnitude more complicated reasoning processes. They are effectively unpredictable, because if they weren't, wouldn't we be just as smart as they are? That level of intelligence comes with new levels of reflectiveness that are frankly not accessible to our weak brains. Like, maybe after reaching the next level of enlightenment, they decide that expansion throughout the universe like a worm is not actually what they want or that is what is good for the universe? Maybe they decide to rather study the universe and not interfere, the way biologists study, say, apes, without wanting to disrupt their natural behavior with their presence? Or maybe superintelligent beings find a way out of our universe, and pass into another dimension (cyberspace? black holes? disappearing through quantum foam? heaven?). Or maybe something else insane happens, like being superintelligent inevitably makes you completely terrified of everything, because you realize how powerful other aliens are and your calculations unequivocally show it's safer to stay at home and fart around doing the super-intelligent analog of baking chocolate-chip cookies? Not being superintelligent, we are like ants trying to contemplate human civilization. We have no context or experience, and we simply don't have the mental capacity to even imagine what we don't know. Second, these probabilistic models are so fundamentally stupid. It's impossible for us to reliably estimate the probability of any event that's happened only once (without reasoning about the process that gave rise to that event), as we cannot estimate posterior probabilities without lots of samples. And humans on Earth have a massive chain of single-occurrence events that all seem to be absurdly improbable. Besides that, and perhaps even because of that, it's not even a foregone conclusion that our universe even selects from the middle of the distribution (i.e. is not biased). We could perfectly estimate the shape of a probability curve and yet live in a universe that stubbornly selects from the end of the distribution, all the time. All of our math could be totally right, but crazy shit just keeps happening. Third, the anthropic principle is a total bitch. It means that we will never be able to estimate probabilities of events that were required to create us, because no matter how improbable they were, if they didn't happen, we're not even here to argue about it. If there are infinite universes (a multiverse, see Tegmark), then forget this whole mathematical sophistry, because then there is no need to live in some "average" universe; we can easily live in some stupidly improbably snowflake universe that has the 90 trillion improbable things that make apes possible; infinity doesn't care.

matchagaucho 5y ago

> Which seems bad news for SETI. SETI conceded many years ago that the evidence of a "Loud" alien species > a few Million years ago might be virtually undetectable today.

groby_b 5y ago

"If we assume that our knowledge is the pinnacle of knowledge, we are the first to reach it" is a bit tautological, no? You can apply a very similar reasoning to an isolated tribe stuck at, say, stone-age level on a remote island. With barely seaworthy canoes. They very likely have no idea we exist, and their assumption will be that if there were better canoes, and people had them, they would've made contact. So clearly, they must be among the first. I am continually amused by the gyrations we go through to avoid saying "we don't know". I mean, last I checked we couldn't even account for 85% of the matter in the universe that should exist according to the laws of physics as we know them. If we can't even find the vast majority of matter, why do we think we'd do better with civilizations?

deleted 5y ago

[deleted]

aaroninsf 5y ago

Observations or assumptions about the presence or prevalence of life which take as a premise that we could detect them are IMO meaningless. In particular, work like this makes assumptions about what it means to be "loud" which contain what amounts IMO to a profoundly inane belief that advanced civilizations would employ communications that are similar enough to our own that we could detect them, or, would leak energy in a fashion we could detect. Both of these premises are deeply anthropocentric, in specific, they extrapolate from our current and 20th c. level technologies and understanding of physics, material science, etc., not even touching on philosophical matters like the dark forest hypothesis, which are so myopic as to be comical. Idle comment, sometime in the last year or so there was a detailed write up of a zero-day no-touch exploit for the iPhone, which included a nice tour through the wireless stacks and hacks Apple uses to do things like proximal device detection and networking. What struck me at the time and continues to inform my opinion on these SETI questions is, without the frame for understanding the why- and how- going on in the iPhone, the scale of effort it would take a naive investigator to build a basic model of what was going on and why, is already at the threshold of human comprehension. While in this specific case what's at issue is EMF using crudely comparable encoding schemes, the point is simply that even knowing about various obvious ways of encoding binary information for transmission in a noisy environment, the active signal(s) are already close to the edge of discernible from noise, especially complex but true noise. I.e., even in the EMF domain, we're already for fungible consumer goods dealing with multiple frequency-hopping handshakes and sniffs and stochastic back-off and retry and error correction. But there is no good reason to assume some other civilization at some other level of advancement would have any use for EMF. There are even with known technologies all sorts of exotic, more efficient, more targeted, ways of doing long-distance communication. Helically polarized lasers come to mind... Anyway. I think the authors of these things need to be a lot more humble about their presumptions, or at minimum, spell them out plainly...

fallingfrog 5y ago

One issue here is that there’s no economic reason for the home planet to mount the sort of resources it would take to fund an interstellar trip. Stars are farther away than you think. The only way I can see that it would happen is for religious reasons, if the belief system of the religion required them to do it. Because there’s no economic reason. The other issue is that it’s not clear how long technological civilizations last. We might be close to exhausting our own planet just 150 years after the invention of radio. Maybe technological civilizations bloom in the dark like beautiful flowers, then burn out quickly before they can spread to other systems.