22 ms·

If life is very common in the universe, then that is probably bad news for us. It means that civilizations should exist that are millions of years more technol

by ta8645 1y ago

If life is very common in the universe, then that is probably bad news for us. It means that civilizations should exist that are millions of years more technologically advanced than us; and should be leaving telltale signatures across the sky that we'd likely have detected by now. And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. Suggesting that our demise too, will come before too long. If, on the other hand, life is relatively rare, or we're the sole example, our future can't be statistically estimated that way.

FL33TW00D 1y ago
Not so! Humans are just early: https://www.youtube.com/watch?v=l3whaviTqqg https://www.youtube.com/watch?v=l3whaviTqqg
aardvark179 1y ago
You seem to be conflating life, multicellular life, and intelligent life. Life appears to have developed on Earth pretty quickly, multicellular life took a long time to appear, and we are only aware of one species that developed civilisation building capabilities. Life might be very common, but intelligent life still be incrediblY rare.
- falcor84 1y ago
  Indeed. We might finally start getting some real estimates for those factors in the Drake Equation.
- martopix 1y ago
  It depends what you mean by "civilization building". I think we gloss over that a bit too much. We're not the largest population, not the largest total mass, not the only one that builds large structures. We're the only one that sent stuff outside of Earth, yes, and a few other things. But discussing the definition is itself interesting
  - ivan_gammel 1y ago
    We are capable of rapidly changing chemical composition of atmosphere, which may be noticeable even at our technological level.
    - milesrout 1y ago
      Plenty of lifeforms have changed the composition of the atmosphere. At faster rates than we are changing it now.
      - ivan_gammel 1y ago
        Faster? Do you have an example? What species can add 10^12 tons of any chemical in just few hundred years? There were geological events and asteroid impacts that may result in more dramatic changes, but their signatures will be different.
      - concats 1y ago
        The only similar example I can think of is when, roughly 2400 million years ago (during the Paleoproterozoic iirc), the ancestors of cyanobacteria poisoned their atmosphere by overproducing oxygen which resulted in an extinction event. But that whole process still took somewhere in the order of millions of years to complete I believe.
        SideburnsOfDoom 1y ago
        > But that whole process still took somewhere in the order of millions of years to complete I believe. The geological evidence is that that oxygen build-up first had to exhaust things that took the reactive oxygen out of the air and water. Iron oxide was laid down as huge deposits of "banded iron ore" The great rust. (1) This is hard to get an exact number on, but as far as I know, it is estimated to have taken at least 500 million years. And then oxygen increased again, a billion years later (2) It was not fast. It was measured in 100 million year ticks. 1) https://en.wikipedia.org/wiki/Great_Oxidation_Event#Banded_iron_formation https://en.wikipedia.org/wiki/Great_Oxidation_Event#Banded_i... 2) https://en.wikipedia.org/wiki/Neoproterozoic_oxygenation_event https://en.wikipedia.org/wiki/Neoproterozoic_oxygenation_eve...
- goognighz 1y ago
  Intelligent life most like arose from the extinction level events that wiped out less intelligent super predators. This gave those who are far weaker but with higher brain capacity the chance to express their genetic variations.
- trhway 1y ago
  >we are only aware of one species that developed civilization building capabilities. well, the first one just doesn't leave any chance for any other one. >Life might be very common, but intelligent life still be incrediblY rare. the time period between big ape and nuclear bomb is extremely short - few millions years. In a hundred or a thousand - doesn't really matter - years we'll be an interstellar species or may be we destroy ourselves by Covid-2319. The point is that complexity develops exponentially and tremendous changes are happening in an extremely a short period of time - i.e. if life has 4B years to develop when it most probably has 4.01B years to develop civilization.
  - ninetyninenine 1y ago
    Unlikely we will ever be interstellar. The technology involved is speculative and the physics barriers needed to be surpassed are impossible and not well understood. To reach another star by the laws of physics involves many human lifetimes and that’s just the nearest star. That in itself makes it more likely that we will never be interstellar.
    - pfdietz 1y ago
      Slow but plausible starships can be designed with 1960s technology. The obstacle is not the technology but the scale of the effort, a problem that could be solved by extension of civilization into the solar system with much larger populations. https://galileo.phys.virginia.edu/classes/109.jvn.spring00/nuc_rocket/Dyson.pdf https://galileo.phys.virginia.edu/classes/109.jvn.spring00/n...
      - ninetyninenine 1y ago
        Humanity will never put effort into this. We don’t have the technology yet but yes we can develop it but doing this is harder than building a bridge across the ocean between Asia and the US. That bridge is also within our technological capacity. But it’s not happening period.
        1y ago
mnky9800n 1y ago
Most of the sky is left unexplored. I think it’s premature to suggest we don’t see things. There are too many things to see in a single lifetime.
- ta8645 1y ago
  But if there was a Kardashev type III civilization in the Milky Way, they would have had full control of our entire galaxy in a mere 200 million years or so. And we can be pretty sure that such a civilization doesn't actually exist. Which suggests that either advanced life is rare, or dies off long before it ever reaches such technological breadth.
  - oezi 1y ago
    Considering the distances between stars, we might not see civilization spreading as coherent empires but more like humans spreading through the islands of the pacific archipelago. Certainly the same species but also culturally seperated to develop on their own. Unless faster than light travel or communication becomes avaliable, it might not even make sense to travel through the galaxy.
  - simiones 1y ago
    Or this is merely sci-fi and it's physically impossible to build anything even close to such structures as Dyson spheres. There is no reason whatsoever to believe that just because we can conceive of something like that, it's actually possible to build it using real materials in real quantities with real amounts of available energy in a star system, and even less so to maintain these magical devices even if built.
    - jayGlow 1y ago
      you don't need to build a physical shell, a dyson swarm would get the job done.
  - mnky9800n 1y ago
    Maybe they have different motivations than humans because they are aliens.
nurettin 1y ago
Not to take away from you personally, but civilization as we understand it is our own cliche. Organisms developed on different planets could absolutely have a different view on life and society in general. Even on earth we have highly intelligent and physically capable organisms that care naught for your conceptions of how groups should function together. There are even organisms that seem to have no intersection with our set of interests that are way more successful in terms of populating earth and invading space. Putting our understanding and interests at some panacea is just hubris.
- whatever1 1y ago
  I mean game theory and equilibria are universal. I don’t see why the basic rules of civilization would not apply to any level of organism sophistication.
  - nurettin 1y ago
    Yes, but what we live in is well beyond a decision with four outcomes and all this assumes "we are doing it right".
- Imustaskforhelp 1y ago
  Regarding populating earth and invading space. I was just watching the original (first) matrix movie yesterday because I was just too bored. And there was this dialogue by Agent Smith:- ```I’d like to share a revelation during my time here. It came to me when I tried to classify your species. I realized that you’re not actually mammals. Every mammal on this planet instinctively develops a natural equilibrium with the surrounding environment but you humans do not. You move to an area and you multiply and multiply until every natural resource is consumed. The only way you can survive is to spread to another area. There is another organism on this planet that follows the same pattern. Do you know what it is? A virus. Human beings are a disease, a cancer of this planet. You are a plague, and we are the cure.``` So yea, I totally agree with you because just as how Agent Smith compared Humans to a virus and just like we know that not every living thing is a virus, In a similar fashion, I think not every species have intersection with our sets of interests (populating earth,invading space). I actually had just watched matrix for agent smith actually. I don't know why but the guy looks really cool to me for some reason.
volemo 1y ago
If life is quite common, that still leaves an option that we are among the oldest of civilisations. Besides, lack of comical presence doesn’t necessarily mean demise: maybe all face the problematic consequences of uncontrolled industrialisation and go solar punk?
Philip-J-Fry 1y ago
Say another human-like civilisation existed and was more technologically advanced, what sort of tell-tale signs do you expect to see?
- ta8645 1y ago
  Scientists use the term "technosignatures", which you can google for more info. But broadly: radio signals, infrared from megastructures, optical signals like laser pulses. We haven't put a huge amount of effort in searching for such signatures, but there has been some.
  - rsynnott 1y ago
    Thing is, though, it kind of assumes megastructures. AIUI Earth is already getting less radio-noise-y, as fibre-optics take over, and would be difficult for us to detect from the next star (at least to detect the technological civilisation; the biosignatures would be obvious). Maybe people just don't _actually_ build that many megastructures.
  - alchemist1e9 1y ago
    I’m personally not convinced advanced civilizations would necessarily exhibit such technosignatures at all. I even go as far and ask are you sure if an advanced civilization was living and mining in Saturn’s rings we would even notice? If one considers the scales of things and realizes how big the Saturn system is relative to Earth then I doubt they can be so confident we would even notice our neighbors in the solar system yet.
  - floatrock 1y ago
    Another possibility is we're looking for the wrong techno signatures, or just haven't conceived what the technosignatures for a 10,000-year technologically advanced civilization are. We've been a techno-civ for what? Maybe only 200-ish years? Our paradigm is gobble up all the energy and grow at all costs. So extrapolate that out, and the logical conclusion is a dyson megasphere that radiates all over the infrared. But then again, that paradigm is careening us towards an environmental and ecosystem collapse: the hunger for infinite growth is warming our climate, it's unclear whether our nuclear-armed social structures can handle the coming disruptions and migrations, and if we don't kill ourselves, unclear how big a population all the environmental degradation and pollution can support. So we can project our cute 200-year-old patterns out to a maybe-discoverable 10,000-year civilization driven by the same motivations and flows, but those extrapolations quickly run up against some pretty existential pragmatic threats. Maybe the answer is we aren't seeing any of the technosignatures because the techonsignatures on the other side of the Great Filter look very different from the ones we conceive of now.
okamiueru 1y ago
Not sure how bad it could be given the hypothetical "millions of years more technologically advanced". They'd need to have a pretty good reason to care about us. Otherwise, we'd be so insignificant that it seems much more likely that whatever natural resources they'd want, would also be likely nearer and easier to obtain. War-mongering, and otherwise zero-sum mentality shouldn't make all sense if they have the technology to actually reach us. [3-body spoiler warning] Kinda like in the Three Body Problem. It was kinda silly how advanced the Trisolarian were, while still bothering traveling to earth, rather than approach the problem in any number of more obvious ways
- exe34 1y ago
  Did you read the parent in haste or did they edit their post? They said: > [1] It means that civilizations should exist that are millions of years more technologically advanced than us; > [2] and should be leaving telltale signatures across the sky that we'd likely have detected by now. > [3] And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. > [4]Suggesting that our demise too, will come before too long. So they were talking about the great filter, not alien invasions, which is what you appear to be replying to.
  - okamiueru 1y ago
    You are exactly right. I think I was tired and simply misread. Thanks for clarifying. Between [3] and [4] I added an assumption, without basis, of implied agency by [1].
- jayGlow 1y ago
  in the book they couldn't stay in their system since it was unstable and our star was the closest to them and they knew we were less advanced than them.
oulipo 1y ago
Possibly a more advanced civilization than us has long understood that it should not try to contact and bother other ones, but rather focus on their happiness where they are
Andrew_nenakhov 1y ago
It is quite plausible that life is abundant, but sentience is not. If we take Earth, it formed 4.5 billions years ago, conditions became suitable to support life like 4B years ago and first known signs of life are dated 3.7B years ago. Now, in just .5B years Earth would likely become uninhabitable due to Sun becoming a red giant. In other words, on Earth life spent 90% of its total available time before sentience emerged. So on one side life is constrained simply by time, and on the other, sentience might not be necessary for organisms to thrive: crocodiles are doing just fine without one for hundreds of millions of years. To think of it, it is only needed for those who can't adapt to the environment without it, so humans really might be very special, indeed.
- dtech 1y ago
  The sun has about 5B years more to go before it turns into a red giant, not 0.5B years...
  - IsTom 1y ago
    While it has more time to become a red giant, it'll become more luminous over time and life on Earth will be impossible much earlier. I've seen estimates of 0.5B to 1.5B years.
    - DiogenesKynikos 1y ago
      In 500 million years, hopefully humans (or whatever humans have become at that point) will be able to modify the Earth's atmosphere to deal with the increased luminosity of the Sun.
      - meindnoch 1y ago
        We'll put a giant sunshade in the Earth-Sun L1 Lagrange point.
        Nevermark 1y ago
pif 1y ago
> that is probably bad news for us. Apart from the Sun, the nearest star to us is four light-years away. I'm not loosing my sleep on the thought of being "discovered" by anyone over there.
ivan_gammel 1y ago
> And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. If dark forest theory is right, alien civilizations may stay undetectable by hiding biological signatures of their worlds.
- milesrout 1y ago
  And the evidence of that is what? What is the mechanism behind that? How is it testable? This is what annoys me about this field. It is just magical thinking and baseless speculation. Random ideas get given names like "dark forest theory" like they are deep and consequential. What you said is the only consequence of that "theory", because that "theory" is literally just the idle speculation that "alien civilizations may stay undetectable by hiding biological signatures of their worlds."
  - ivan_gammel 1y ago
    It’s game theory, mathematics. Let’s say every player has 3 actions: do nothing, expose yourself and destroy the player you aware about. Your goal is survival. If you expose yourself in this game and there’s at least one player choosing „destroy“ action, you loose. Now, of course there’s a question of applicability of this model: 1. are there other players? (if the game started, we won’t know until we observe destruction event - but that’s falsifiability) 2. do they have means to destroy you? (we may find out) 3. do they have motivation to destroy you? (we may find out) 4. can you protect yourself against unknown level of technology? (we may find out). This theory meets scientific criteria, it’s just that those criteria require level of technology that we may not reach in thousands of years.
- vladimirralev 1y ago
  Dark forest theory is wrong. Staying undetectable is always inferior to both staying undetectable and safely deploying varyingly detectable decoy targets at safe distance to probe the situation and gather intelligence.
  - ivan_gammel 1y ago
fy20 1y ago
Maybe there's some truth to Douglas Adams' writing - we are just insignificant enough that nobody cares. In the Star Trek series it's similar, they are interested to see how pre-warp civilisations develop, seeing them as quaint, but that's it. > Far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this at a distance of roughly ninety-two million miles is an utterly insignificant little blue green planet whose ape-descended life forms are so amazingly primitive that they still think digital watches are a pretty neat idea.
meindnoch 1y ago
>It means that civilizations should exist that are millions of years more technologically advanced than us; and should be leaving telltale signatures across the sky that we'd likely have detected by now. Or they've reached their technological plateau millions of years ago. Like we did 50 years ago. >And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. We know for a fact that life have existed on Earth for >2 billion years.
- davedx 1y ago
  > Or they've reached their technological plateau millions of years ago. Like we did 50 years ago. What a bizarre thing to say, considering this very discovery leans on decades of science and engineering over the past 50 years!
  - meindnoch 1y ago
    None of those discoveries help with space travel whatsoever. Our most advanced space propulsion still works on the principle of throwing a lump of matter in the opposite direction. The rocket equation remains undefeated. Special relativity remains undefeated. This is the plateau that I'm talking about. And we have zero idea if anything can be done about it.
  - fullstackchris 1y ago
    Many trolls hiding in these comments... either that or they just dont understand what the scientific method is.
Ekaros 1y ago
Maybe technology development is not exponential but s-curve. And anything large scale is impossible. So outside some radio signals there would not be any grand things that could be observed.
Scarblac 1y ago
I see it differently -- if we are all alone, then our disappearance will be an unfathomable catastrophe. If it's abundant, well, so it goes.
- Imustaskforhelp 1y ago
  What do we mean by alone? Life isn't this "magical" force. Life is just an outcome which is just incredibly rare. Or maybe its not? Maybe we are just too primitive in the sense that we haven't analyzed all planets (like this planet is just 120 light years away, still huge but still, who knows how this search continues, and maybe we can even find more/maybe advanced species as well? But also, as others have pointed out. I think that getting to civilisation level is pretty rare. Its not like the signs on this life that we have found automatically means that they are one day going to be a civilization level life. They may or may not & so many other comments above this comment have beautifully shown the amount of rarity in that which was the major takeaway from this HN atleast for me. Its still just so fascinating how human societies exist. Maybe I am pessimistic, but like we believe in gold because everyone else does, but for the first time ever, Imagine the people who started trusting in gold and started trading in gold. They couldn't eat gold, For all its worth, they might have thought that its just shiny rock and its abundant, we just haven't discovered it yet and its going to be worthless so we might as well use grains. But such trust in gold,maybe even religion/ general trust on society structure beyond the people you know directly is just so bizarre. People believing and dying for nations made those nations have power. And now we trust those nations and their power because our ancestors said so & taught us so. I have read sapiens book 4-5 years ago and I think I had never wondered about such things until now. Our ancestors could change things way more radically. They had such freedom. Voltaire used his reason to pursuade people for a revolution. I am not sure, but in the vastness of the internet, people have just stopped caring about reason but rather all they care about is authority. Change fears so many people. People would know that some things are bad yet just because they exist, they think it as something so highly and won't even conceive of the possibility of fixing it. And others would be peer pressured into we can't change it. And the people who want change would be ridiculed and made fun of. So much of the time, reason falls off on dead ears in today's world & emotions are hijacked by echo chambers. Much of our society(I can't say nobody,because I would do grave injustice to people who reason) wants to reason because we want the comfort of emotion.
tiborsaas 1y ago
We don't have to look to the stars to tell that humans have a horrible tendency to make the majority's life a struggle and constantly balancing on the verge of demise.
goognighz 1y ago
Dark forest hypothesis explains this in a “dark” way. They exist but are smart enough to hide from hostile hunter/predator life forms. Meanwhile our dumbasses are blasting radio signals into space like a little kid trying to talk to every stranger they see.
- Intralexical 1y ago
  It's also largely bunk. More a story than a hypothesis, really. Game theory shows cooperation beats aggression on a long enough timescale. Politics shows alliances and MAD deters first strike. Even actual "dark forests" are full of animals that have bright colors and make loud noises.
  - joseppu 1y ago
    I really wish natives of places we discovered knew about this. they could've evaded all the bad parts and just explained how it is just a story.
    - Intralexical 1y ago
      The Indigenous peoples of the Americas knew well enough about the value of cooperation and alliance. That's why they had stuff like the Iroquois Confederacy, and switched between working with the British, the French, and the colonies depending on which was best for each individual group of natives at any one time. To present them as pure victims powerless before the might of white settlers undermines the political and cultural agency that Native peoples in fact had, and exercised. The predominant form of relationship between European and Native American peoples for hundreds of years was trade, not war. The tragedies and the atrocities that resulted were a slow burn of conflicting interests and epidemiological naïveté, both between Europeans and Natives and also within each group. That's quite different from the hiding and decapitation strikes usually presented as "dark forest hypothesis", because there's no reason that those specific interests and ignorance would carry over to interstellar society (and every reason that they would need to be overcome in order to become interstellar in the first place). But why do people always use the fate of resource-constrained preindustrial societies (both Europe and America) to try to predict relationships between hyper-advanced Kardashev-level civilizations anyway? It really seems to me like some kind of projected shame. You can see this too with Liu Cixin. He came from a country that was recently dominated, and has more recently been preparing to dominate its neighbors, so his story pretends nothing better is possible. I suppose that's comforting for some, and questioning it brings out people who show what it's really about. Google Trends shows the top 10 countries for "Dark forest hypothesis" include the US, Taiwan, China, Peurto Rico, HK, Canada, and Aus [1]— Places with a prominent recent or ongoing imperial history, whether as victims or victimizers. I actually find the "dark forest" narratives quite disturbing, not as a prediction of our future, but as a window into the psyche of people who seem to want it to be one. You might as well say the Romans had a slave-based economy, so therefore spacefaring empires must also be looking for human slaves! That's got exactly the same amount of validity as the Native comparison. But economic and military incentives obviously change as technology and culture develops. If anything, the fact we used to kill a lot of natives, and we don't so much anymore, is a strong sign that advanced societies can trend towards being less genocidal. 1: https://trends.google.com/trends/explore?q=%2Fg%2F11jyk5h9nj&hl=en-US https://trends.google.com/trends/explore?q=%2Fg%2F11jyk5h9nj...
Intralexical 1y ago
Maybe they just don't feel the need to blast their emissions all over the sky like some sort of a caveman. Our own technological signature is coming to form a very thin shell. Once we switch fully to fiber optics, lasers, and beamformers, there won't be any aliens learning English from listening in on our TV transmissions anymore. Radio broadcasting was cool, but also horribly wasteful. It's probably incorrect to assume that more technologically advanced civilizations would be louder.
fullstackchris 1y ago
Bostrom's trilemma and the notion of the Great Filter! But in the grand scheme of things, even its "bad news" just ONE datapoint of life elsewhere is at least something to start working with.
dotancohen 1y ago
> And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. Stars are abundant, long-lived, and go through cycles of life and death. Now look at the night sky. The chance that you eye will detect a star at any given patch of sky that is roughly the size of a star, is nearly nill. That is not bad news for those who wish to see that stars continue to exist - it is a feature of the size, vastness, and expansion of the universe. Same for life, presumably.
voidUpdate 1y ago
Conversely, it should mean there would also be lots of civilisations millions of years technologically behind us. We're more likely to be an average civilisation than the least-developed
ninetyninenine 1y ago
The probability of advanced civilization is given the probability of life is quite low itself. For the overwhelming majority of time life has existed on earth only a minuscule part of it involved civilization. And an even more minuscule part of it involved technology that has a small chance to send a coherent signal to another star. Our future is easily estimated by the hardness of traveling through space and the demise of our sun. Probability points to the end humanity by way of the death of our star. We are statistically most likely to end.
nbadg 1y ago
I often wonder if the answer to the Fermi paradox isn't just as extremely banal as "turns out that interstellar exploration just isn't economically viable". I think it's entirely plausible that advanced economies are circular, and that within a circular economy, it's just extremely difficult to justify the massive expenditure of resources that it would take to become interstellar. I mean, think about how many stars had to align to catalyze our first steps on the moon. Now, 53 years later, we're just starting to put serious effort into going back -- not because there's any market reason to do so, but because (once again) there's political pressure for it. Which would suggest that the best case scenario for the current exploration efforts are something along the lines of what we already see in Antarctica: a well-staffed scientific presence that does really cool/valuable work, but nothing remotely approaching even a single major city in terms of human presense. It seems to me that one of the unwritten priors to the Fermi paradox (at least in popular discourse) is that technology is the only prerequisite to expanding a civilization; in other words, if you have the technology, then interstellar expansion is only a matter of time, and that all civilizations will inevitably eventually develop the technology. And that... seems like a pretty big assumption, if human history is any indication.
- cmsj 1y ago
  The thinking generally would be that while it might take political pressure to initially begin leaving the home planet, once politics has unlocked that capability, commerce will take over. If we were to begin mining the solar system, it unlocks vast pools of resources that would really change things. That said, interstellar travel is still a pipe dream because of the time involved. Without finding a cheat code for physics, it may well be that intelligent life is always trapped in its home system and has to live and die within the limitations of stellar evolution.
  - Earw0rm 1y ago
    Vast pools of /what/ though? It seems, at present, that energy is more of a constraint on civilization than matter. With unlimited cheap energy, there's enough material to do most anything we might reasonably want. It's likely to cost $thousands/kg to bring materials back from beyond Earth orbit. There are only a handful of elements valuable enough, and that's if they existed in pure form. Hypothetically, if an asteroid made of pure gold existed, and if a Cargo Dragon atop a Falcon Heavy had enough delta-V to make it there and back with a couple of tonnes, it might break even, but all of this is doubtful. Most valuable minerals are worth hundreds to low thousands of dollars per kg, so you need a launcher that can bring back a ton of rock for $1M - and not from LEO, you probably need to escape Earth's gravity and get back again. The physics and engineering are proven, but the economics? Unlikely. Put another way, you can mine a heck of a lot of Earth rocks with a rocket's worth of kerosene.
mpalmer 1y ago
> millions of years more technologically advanced than us > should be leaving telltale signatures across the sky that we'd likely have detected by now I'm not sure the second follows from the first. What if they're hiding?
soneca 1y ago
I always thought that how far things are in the universe and the impossibility of faster than light travel were enough to explain why life might be abundant in the universe yet we never observed it.
vivzkestrel 1y ago
no matter how advanced the civilization is, proxima centauri will always be 42 trillion kms away. Our civilization in current stage is not even close to 0.1% the speed of light but lets say your advanced civilization goes at 99% the speed of light, still doesnt change the fact they need 4.25 years approx to reach earth. Still doesnt change the fact that unless they have a 1 billion km wide telscope, they cannot reliably tell if earth has life or not. So basically you are asking them to take a shot at coming to the solar system on a 5 yr trip when they have no idea what is found here. Now extrapolate the numbers for the average 100 light year trip between 2 points on our galaxy and you ll quickly realize why we dont have aliens
- dash2 1y ago
  > Still doesnt change the fact that unless they have a 1 billion km wide telscope, they cannot reliably tell if earth has life or not. How come we’re making progress on this without a 1bn km telescope?
  - 986aignan 1y ago
    And even that notwithstanding, they could use a solar foci telescope. It's kind of a pain to orient, but it /does/ give you extreme magnification.
- globular-toast 1y ago
  If they came here and back at .99c it would be ~70 years "time debt"[0] for them (meaning 70 years would have passed for their relatives back home). [0] Terminology from Dan Simmons's Hyperion. Would also recommend Joe Haldeman's The Forever War for more time dilation themes.
- glimshe 1y ago
  Where did you get the 1bn km number? I'm asking it seriously, I'd like to better understand how to calculate these things.
  - vivzkestrel 1y ago
sixQuarks 1y ago
There is no way civilizations make it past a certain point. It’s so completely obvious, just look at our world. In 2025 we are enabling a genocide while the masses don’t seem to care or even know about it. You think the people that are having these types of atrocities committed against them would think twice about ending civilization as revenge if given the power? What do you think is going to happen with AI? If we can’t stop a genocide, why would you think we can stop civilization ending?
halgir 1y ago
Someone has to be the first. Granted, us being first is extremely unlikely. But the same is true for whoever it ends up having been.
psychoslave 1y ago
Also even if it's low, it's not impossible that human technology actually is the one with the more advanced in its observable part of the universe. That is, if there is supposedly one civilisation with clear advance in technology, it could just as well be humanity.
pc86 1y ago
It's extremely likely that our demise will come before too long. The problem is that "before too long" is on a universal timescale, not a human timescale. Humanity could exist for a million times longer than it already has, expand to other planets in our solar system and even to another solar system or two, be wiped out completely, and on the appropriate timescale we were absolutely "short lived."
throw4847285 1y ago
This is where the discussion, as it always does, silently transitions from science into science fiction. We know absolutely nothing about extraterrestrial life. We can only project our own singular experience onto the rest of the universe. We only have one data point. There is no scientifically acceptable method of induction from a single data point. The possibilities are endless, and are capacity to narrow them down becomes warped by our love of stories and the kinds of art that we have created about extraterrestial life, all of which are in one way or another metaphors for the human condition. There is nothing wrong with saying, "Anything is possible and we have 0 evidence allowing us to narrow it down." It isn't fun, but it's true.
mbfg 1y ago
The thing is we've only been around a tiny period of time, and given the size of the universe, it would have to be an amazingly tiny Goldilocks zone in time to actually notice us, let alone do anything about it.
perlgeek 1y ago
Even if civilizations are relatively common (which, as others have pointed out, doesn't necessarily follow from life being common), the distances involved are really huge. We have some ideas for crossing huge distances, but none of them are really practical. There are ideas for accelerating tiny probes with light sails, but when we manage to send them somewhere with 90% of the speed of light, we have no way to decelerate them again in a controlled fashion. What I want to say is: there's good reason to think that doing anything over 200 light years or so is just infeasible.
jschulenklopper 1y ago
> relatively strong evidence that life, while common, isn't long-lived. https://en.wikipedia.org/wiki/Great_Filter https://en.wikipedia.org/wiki/Great_Filter

by ta8645 1y ago

FL33TW00D 1y ago

Not so! Humans are just early: https://www.youtube.com/watch?v=l3whaviTqqg https://www.youtube.com/watch?v=l3whaviTqqg

aardvark179 1y ago

You seem to be conflating life, multicellular life, and intelligent life. Life appears to have developed on Earth pretty quickly, multicellular life took a long time to appear, and we are only aware of one species that developed civilisation building capabilities. Life might be very common, but intelligent life still be incrediblY rare.

falcor84 1y ago
Indeed. We might finally start getting some real estimates for those factors in the Drake Equation.
martopix 1y ago
It depends what you mean by "civilization building". I think we gloss over that a bit too much. We're not the largest population, not the largest total mass, not the only one that builds large structures. We're the only one that sent stuff outside of Earth, yes, and a few other things. But discussing the definition is itself interesting
- ivan_gammel 1y ago
  We are capable of rapidly changing chemical composition of atmosphere, which may be noticeable even at our technological level.
  - milesrout 1y ago
    Plenty of lifeforms have changed the composition of the atmosphere. At faster rates than we are changing it now.
    - ivan_gammel 1y ago
      Faster? Do you have an example? What species can add 10^12 tons of any chemical in just few hundred years? There were geological events and asteroid impacts that may result in more dramatic changes, but their signatures will be different.
    - concats 1y ago
      The only similar example I can think of is when, roughly 2400 million years ago (during the Paleoproterozoic iirc), the ancestors of cyanobacteria poisoned their atmosphere by overproducing oxygen which resulted in an extinction event. But that whole process still took somewhere in the order of millions of years to complete I believe.
      - SideburnsOfDoom 1y ago
        > But that whole process still took somewhere in the order of millions of years to complete I believe. The geological evidence is that that oxygen build-up first had to exhaust things that took the reactive oxygen out of the air and water. Iron oxide was laid down as huge deposits of "banded iron ore" The great rust. (1) This is hard to get an exact number on, but as far as I know, it is estimated to have taken at least 500 million years. And then oxygen increased again, a billion years later (2) It was not fast. It was measured in 100 million year ticks. 1) https://en.wikipedia.org/wiki/Great_Oxidation_Event#Banded_iron_formation https://en.wikipedia.org/wiki/Great_Oxidation_Event#Banded_i... 2) https://en.wikipedia.org/wiki/Neoproterozoic_oxygenation_event https://en.wikipedia.org/wiki/Neoproterozoic_oxygenation_eve...
goognighz 1y ago
Intelligent life most like arose from the extinction level events that wiped out less intelligent super predators. This gave those who are far weaker but with higher brain capacity the chance to express their genetic variations.
trhway 1y ago
>we are only aware of one species that developed civilization building capabilities. well, the first one just doesn't leave any chance for any other one. >Life might be very common, but intelligent life still be incrediblY rare. the time period between big ape and nuclear bomb is extremely short - few millions years. In a hundred or a thousand - doesn't really matter - years we'll be an interstellar species or may be we destroy ourselves by Covid-2319. The point is that complexity develops exponentially and tremendous changes are happening in an extremely a short period of time - i.e. if life has 4B years to develop when it most probably has 4.01B years to develop civilization.
- ninetyninenine 1y ago
  Unlikely we will ever be interstellar. The technology involved is speculative and the physics barriers needed to be surpassed are impossible and not well understood. To reach another star by the laws of physics involves many human lifetimes and that’s just the nearest star. That in itself makes it more likely that we will never be interstellar.
  - pfdietz 1y ago
    Slow but plausible starships can be designed with 1960s technology. The obstacle is not the technology but the scale of the effort, a problem that could be solved by extension of civilization into the solar system with much larger populations. https://galileo.phys.virginia.edu/classes/109.jvn.spring00/nuc_rocket/Dyson.pdf https://galileo.phys.virginia.edu/classes/109.jvn.spring00/n...
    - ninetyninenine 1y ago
      Humanity will never put effort into this. We don’t have the technology yet but yes we can develop it but doing this is harder than building a bridge across the ocean between Asia and the US. That bridge is also within our technological capacity. But it’s not happening period.
      - 1y ago

mnky9800n 1y ago

Most of the sky is left unexplored. I think it’s premature to suggest we don’t see things. There are too many things to see in a single lifetime.

ta8645 1y ago
But if there was a Kardashev type III civilization in the Milky Way, they would have had full control of our entire galaxy in a mere 200 million years or so. And we can be pretty sure that such a civilization doesn't actually exist. Which suggests that either advanced life is rare, or dies off long before it ever reaches such technological breadth.
- oezi 1y ago
  Considering the distances between stars, we might not see civilization spreading as coherent empires but more like humans spreading through the islands of the pacific archipelago. Certainly the same species but also culturally seperated to develop on their own. Unless faster than light travel or communication becomes avaliable, it might not even make sense to travel through the galaxy.
- simiones 1y ago
  Or this is merely sci-fi and it's physically impossible to build anything even close to such structures as Dyson spheres. There is no reason whatsoever to believe that just because we can conceive of something like that, it's actually possible to build it using real materials in real quantities with real amounts of available energy in a star system, and even less so to maintain these magical devices even if built.
  - jayGlow 1y ago
    you don't need to build a physical shell, a dyson swarm would get the job done.
- mnky9800n 1y ago
  Maybe they have different motivations than humans because they are aliens.

nurettin 1y ago

Not to take away from you personally, but civilization as we understand it is our own cliche. Organisms developed on different planets could absolutely have a different view on life and society in general. Even on earth we have highly intelligent and physically capable organisms that care naught for your conceptions of how groups should function together. There are even organisms that seem to have no intersection with our set of interests that are way more successful in terms of populating earth and invading space. Putting our understanding and interests at some panacea is just hubris.

whatever1 1y ago
I mean game theory and equilibria are universal. I don’t see why the basic rules of civilization would not apply to any level of organism sophistication.
- nurettin 1y ago
  Yes, but what we live in is well beyond a decision with four outcomes and all this assumes "we are doing it right".
Imustaskforhelp 1y ago
Regarding populating earth and invading space. I was just watching the original (first) matrix movie yesterday because I was just too bored. And there was this dialogue by Agent Smith:- ```I’d like to share a revelation during my time here. It came to me when I tried to classify your species. I realized that you’re not actually mammals. Every mammal on this planet instinctively develops a natural equilibrium with the surrounding environment but you humans do not. You move to an area and you multiply and multiply until every natural resource is consumed. The only way you can survive is to spread to another area. There is another organism on this planet that follows the same pattern. Do you know what it is? A virus. Human beings are a disease, a cancer of this planet. You are a plague, and we are the cure.``` So yea, I totally agree with you because just as how Agent Smith compared Humans to a virus and just like we know that not every living thing is a virus, In a similar fashion, I think not every species have intersection with our sets of interests (populating earth,invading space). I actually had just watched matrix for agent smith actually. I don't know why but the guy looks really cool to me for some reason.

volemo 1y ago

If life is quite common, that still leaves an option that we are among the oldest of civilisations. Besides, lack of comical presence doesn’t necessarily mean demise: maybe all face the problematic consequences of uncontrolled industrialisation and go solar punk?

Philip-J-Fry 1y ago

Say another human-like civilisation existed and was more technologically advanced, what sort of tell-tale signs do you expect to see?

ta8645 1y ago
Scientists use the term "technosignatures", which you can google for more info. But broadly: radio signals, infrared from megastructures, optical signals like laser pulses. We haven't put a huge amount of effort in searching for such signatures, but there has been some.
- rsynnott 1y ago
  Thing is, though, it kind of assumes megastructures. AIUI Earth is already getting less radio-noise-y, as fibre-optics take over, and would be difficult for us to detect from the next star (at least to detect the technological civilisation; the biosignatures would be obvious). Maybe people just don't _actually_ build that many megastructures.
- alchemist1e9 1y ago
  I’m personally not convinced advanced civilizations would necessarily exhibit such technosignatures at all. I even go as far and ask are you sure if an advanced civilization was living and mining in Saturn’s rings we would even notice? If one considers the scales of things and realizes how big the Saturn system is relative to Earth then I doubt they can be so confident we would even notice our neighbors in the solar system yet.
- floatrock 1y ago
  Another possibility is we're looking for the wrong techno signatures, or just haven't conceived what the technosignatures for a 10,000-year technologically advanced civilization are. We've been a techno-civ for what? Maybe only 200-ish years? Our paradigm is gobble up all the energy and grow at all costs. So extrapolate that out, and the logical conclusion is a dyson megasphere that radiates all over the infrared. But then again, that paradigm is careening us towards an environmental and ecosystem collapse: the hunger for infinite growth is warming our climate, it's unclear whether our nuclear-armed social structures can handle the coming disruptions and migrations, and if we don't kill ourselves, unclear how big a population all the environmental degradation and pollution can support. So we can project our cute 200-year-old patterns out to a maybe-discoverable 10,000-year civilization driven by the same motivations and flows, but those extrapolations quickly run up against some pretty existential pragmatic threats. Maybe the answer is we aren't seeing any of the technosignatures because the techonsignatures on the other side of the Great Filter look very different from the ones we conceive of now.

okamiueru 1y ago

Not sure how bad it could be given the hypothetical "millions of years more technologically advanced". They'd need to have a pretty good reason to care about us. Otherwise, we'd be so insignificant that it seems much more likely that whatever natural resources they'd want, would also be likely nearer and easier to obtain. War-mongering, and otherwise zero-sum mentality shouldn't make all sense if they have the technology to actually reach us. [3-body spoiler warning] Kinda like in the Three Body Problem. It was kinda silly how advanced the Trisolarian were, while still bothering traveling to earth, rather than approach the problem in any number of more obvious ways

exe34 1y ago
Did you read the parent in haste or did they edit their post? They said: > [1] It means that civilizations should exist that are millions of years more technologically advanced than us; > [2] and should be leaving telltale signatures across the sky that we'd likely have detected by now. > [3] And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. > [4]Suggesting that our demise too, will come before too long. So they were talking about the great filter, not alien invasions, which is what you appear to be replying to.
- okamiueru 1y ago
  You are exactly right. I think I was tired and simply misread. Thanks for clarifying. Between [3] and [4] I added an assumption, without basis, of implied agency by [1].
jayGlow 1y ago
in the book they couldn't stay in their system since it was unstable and our star was the closest to them and they knew we were less advanced than them.

oulipo 1y ago

Possibly a more advanced civilization than us has long understood that it should not try to contact and bother other ones, but rather focus on their happiness where they are

Andrew_nenakhov 1y ago

It is quite plausible that life is abundant, but sentience is not. If we take Earth, it formed 4.5 billions years ago, conditions became suitable to support life like 4B years ago and first known signs of life are dated 3.7B years ago. Now, in just .5B years Earth would likely become uninhabitable due to Sun becoming a red giant. In other words, on Earth life spent 90% of its total available time before sentience emerged. So on one side life is constrained simply by time, and on the other, sentience might not be necessary for organisms to thrive: crocodiles are doing just fine without one for hundreds of millions of years. To think of it, it is only needed for those who can't adapt to the environment without it, so humans really might be very special, indeed.

dtech 1y ago
The sun has about 5B years more to go before it turns into a red giant, not 0.5B years...
- IsTom 1y ago
  While it has more time to become a red giant, it'll become more luminous over time and life on Earth will be impossible much earlier. I've seen estimates of 0.5B to 1.5B years.
  - DiogenesKynikos 1y ago
    In 500 million years, hopefully humans (or whatever humans have become at that point) will be able to modify the Earth's atmosphere to deal with the increased luminosity of the Sun.
    - meindnoch 1y ago
      We'll put a giant sunshade in the Earth-Sun L1 Lagrange point.
      - Nevermark 1y ago

pif 1y ago

> that is probably bad news for us. Apart from the Sun, the nearest star to us is four light-years away. I'm not loosing my sleep on the thought of being "discovered" by anyone over there.

ivan_gammel 1y ago

> And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. If dark forest theory is right, alien civilizations may stay undetectable by hiding biological signatures of their worlds.

milesrout 1y ago
And the evidence of that is what? What is the mechanism behind that? How is it testable? This is what annoys me about this field. It is just magical thinking and baseless speculation. Random ideas get given names like "dark forest theory" like they are deep and consequential. What you said is the only consequence of that "theory", because that "theory" is literally just the idle speculation that "alien civilizations may stay undetectable by hiding biological signatures of their worlds."
- ivan_gammel 1y ago
  It’s game theory, mathematics. Let’s say every player has 3 actions: do nothing, expose yourself and destroy the player you aware about. Your goal is survival. If you expose yourself in this game and there’s at least one player choosing „destroy“ action, you loose. Now, of course there’s a question of applicability of this model: 1. are there other players? (if the game started, we won’t know until we observe destruction event - but that’s falsifiability) 2. do they have means to destroy you? (we may find out) 3. do they have motivation to destroy you? (we may find out) 4. can you protect yourself against unknown level of technology? (we may find out). This theory meets scientific criteria, it’s just that those criteria require level of technology that we may not reach in thousands of years.
vladimirralev 1y ago
Dark forest theory is wrong. Staying undetectable is always inferior to both staying undetectable and safely deploying varyingly detectable decoy targets at safe distance to probe the situation and gather intelligence.
- ivan_gammel 1y ago

fy20 1y ago

Maybe there's some truth to Douglas Adams' writing - we are just insignificant enough that nobody cares. In the Star Trek series it's similar, they are interested to see how pre-warp civilisations develop, seeing them as quaint, but that's it. > Far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this at a distance of roughly ninety-two million miles is an utterly insignificant little blue green planet whose ape-descended life forms are so amazingly primitive that they still think digital watches are a pretty neat idea.

meindnoch 1y ago

>It means that civilizations should exist that are millions of years more technologically advanced than us; and should be leaving telltale signatures across the sky that we'd likely have detected by now. Or they've reached their technological plateau millions of years ago. Like we did 50 years ago. >And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. We know for a fact that life have existed on Earth for >2 billion years.

davedx 1y ago
> Or they've reached their technological plateau millions of years ago. Like we did 50 years ago. What a bizarre thing to say, considering this very discovery leans on decades of science and engineering over the past 50 years!
- meindnoch 1y ago
  None of those discoveries help with space travel whatsoever. Our most advanced space propulsion still works on the principle of throwing a lump of matter in the opposite direction. The rocket equation remains undefeated. Special relativity remains undefeated. This is the plateau that I'm talking about. And we have zero idea if anything can be done about it.
- fullstackchris 1y ago
  Many trolls hiding in these comments... either that or they just dont understand what the scientific method is.

Ekaros 1y ago

Maybe technology development is not exponential but s-curve. And anything large scale is impossible. So outside some radio signals there would not be any grand things that could be observed.

Scarblac 1y ago

I see it differently -- if we are all alone, then our disappearance will be an unfathomable catastrophe. If it's abundant, well, so it goes.

Imustaskforhelp 1y ago
What do we mean by alone? Life isn't this "magical" force. Life is just an outcome which is just incredibly rare. Or maybe its not? Maybe we are just too primitive in the sense that we haven't analyzed all planets (like this planet is just 120 light years away, still huge but still, who knows how this search continues, and maybe we can even find more/maybe advanced species as well? But also, as others have pointed out. I think that getting to civilisation level is pretty rare. Its not like the signs on this life that we have found automatically means that they are one day going to be a civilization level life. They may or may not & so many other comments above this comment have beautifully shown the amount of rarity in that which was the major takeaway from this HN atleast for me. Its still just so fascinating how human societies exist. Maybe I am pessimistic, but like we believe in gold because everyone else does, but for the first time ever, Imagine the people who started trusting in gold and started trading in gold. They couldn't eat gold, For all its worth, they might have thought that its just shiny rock and its abundant, we just haven't discovered it yet and its going to be worthless so we might as well use grains. But such trust in gold,maybe even religion/ general trust on society structure beyond the people you know directly is just so bizarre. People believing and dying for nations made those nations have power. And now we trust those nations and their power because our ancestors said so & taught us so. I have read sapiens book 4-5 years ago and I think I had never wondered about such things until now. Our ancestors could change things way more radically. They had such freedom. Voltaire used his reason to pursuade people for a revolution. I am not sure, but in the vastness of the internet, people have just stopped caring about reason but rather all they care about is authority. Change fears so many people. People would know that some things are bad yet just because they exist, they think it as something so highly and won't even conceive of the possibility of fixing it. And others would be peer pressured into we can't change it. And the people who want change would be ridiculed and made fun of. So much of the time, reason falls off on dead ears in today's world & emotions are hijacked by echo chambers. Much of our society(I can't say nobody,because I would do grave injustice to people who reason) wants to reason because we want the comfort of emotion.

tiborsaas 1y ago

We don't have to look to the stars to tell that humans have a horrible tendency to make the majority's life a struggle and constantly balancing on the verge of demise.

goognighz 1y ago

Dark forest hypothesis explains this in a “dark” way. They exist but are smart enough to hide from hostile hunter/predator life forms. Meanwhile our dumbasses are blasting radio signals into space like a little kid trying to talk to every stranger they see.

Intralexical 1y ago
It's also largely bunk. More a story than a hypothesis, really. Game theory shows cooperation beats aggression on a long enough timescale. Politics shows alliances and MAD deters first strike. Even actual "dark forests" are full of animals that have bright colors and make loud noises.
- joseppu 1y ago
  I really wish natives of places we discovered knew about this. they could've evaded all the bad parts and just explained how it is just a story.
  - Intralexical 1y ago
    The Indigenous peoples of the Americas knew well enough about the value of cooperation and alliance. That's why they had stuff like the Iroquois Confederacy, and switched between working with the British, the French, and the colonies depending on which was best for each individual group of natives at any one time. To present them as pure victims powerless before the might of white settlers undermines the political and cultural agency that Native peoples in fact had, and exercised. The predominant form of relationship between European and Native American peoples for hundreds of years was trade, not war. The tragedies and the atrocities that resulted were a slow burn of conflicting interests and epidemiological naïveté, both between Europeans and Natives and also within each group. That's quite different from the hiding and decapitation strikes usually presented as "dark forest hypothesis", because there's no reason that those specific interests and ignorance would carry over to interstellar society (and every reason that they would need to be overcome in order to become interstellar in the first place). But why do people always use the fate of resource-constrained preindustrial societies (both Europe and America) to try to predict relationships between hyper-advanced Kardashev-level civilizations anyway? It really seems to me like some kind of projected shame. You can see this too with Liu Cixin. He came from a country that was recently dominated, and has more recently been preparing to dominate its neighbors, so his story pretends nothing better is possible. I suppose that's comforting for some, and questioning it brings out people who show what it's really about. Google Trends shows the top 10 countries for "Dark forest hypothesis" include the US, Taiwan, China, Peurto Rico, HK, Canada, and Aus [1]— Places with a prominent recent or ongoing imperial history, whether as victims or victimizers. I actually find the "dark forest" narratives quite disturbing, not as a prediction of our future, but as a window into the psyche of people who seem to want it to be one. You might as well say the Romans had a slave-based economy, so therefore spacefaring empires must also be looking for human slaves! That's got exactly the same amount of validity as the Native comparison. But economic and military incentives obviously change as technology and culture develops. If anything, the fact we used to kill a lot of natives, and we don't so much anymore, is a strong sign that advanced societies can trend towards being less genocidal. 1: https://trends.google.com/trends/explore?q=%2Fg%2F11jyk5h9nj&hl=en-US https://trends.google.com/trends/explore?q=%2Fg%2F11jyk5h9nj...

Intralexical 1y ago

Maybe they just don't feel the need to blast their emissions all over the sky like some sort of a caveman. Our own technological signature is coming to form a very thin shell. Once we switch fully to fiber optics, lasers, and beamformers, there won't be any aliens learning English from listening in on our TV transmissions anymore. Radio broadcasting was cool, but also horribly wasteful. It's probably incorrect to assume that more technologically advanced civilizations would be louder.

fullstackchris 1y ago

Bostrom's trilemma and the notion of the Great Filter! But in the grand scheme of things, even its "bad news" just ONE datapoint of life elsewhere is at least something to start working with.

dotancohen 1y ago

> And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. Stars are abundant, long-lived, and go through cycles of life and death. Now look at the night sky. The chance that you eye will detect a star at any given patch of sky that is roughly the size of a star, is nearly nill. That is not bad news for those who wish to see that stars continue to exist - it is a feature of the size, vastness, and expansion of the universe. Same for life, presumably.

voidUpdate 1y ago

Conversely, it should mean there would also be lots of civilisations millions of years technologically behind us. We're more likely to be an average civilisation than the least-developed

ninetyninenine 1y ago

The probability of advanced civilization is given the probability of life is quite low itself. For the overwhelming majority of time life has existed on earth only a minuscule part of it involved civilization. And an even more minuscule part of it involved technology that has a small chance to send a coherent signal to another star. Our future is easily estimated by the hardness of traveling through space and the demise of our sun. Probability points to the end humanity by way of the death of our star. We are statistically most likely to end.

nbadg 1y ago

I often wonder if the answer to the Fermi paradox isn't just as extremely banal as "turns out that interstellar exploration just isn't economically viable". I think it's entirely plausible that advanced economies are circular, and that within a circular economy, it's just extremely difficult to justify the massive expenditure of resources that it would take to become interstellar. I mean, think about how many stars had to align to catalyze our first steps on the moon. Now, 53 years later, we're just starting to put serious effort into going back -- not because there's any market reason to do so, but because (once again) there's political pressure for it. Which would suggest that the best case scenario for the current exploration efforts are something along the lines of what we already see in Antarctica: a well-staffed scientific presence that does really cool/valuable work, but nothing remotely approaching even a single major city in terms of human presense. It seems to me that one of the unwritten priors to the Fermi paradox (at least in popular discourse) is that technology is the only prerequisite to expanding a civilization; in other words, if you have the technology, then interstellar expansion is only a matter of time, and that all civilizations will inevitably eventually develop the technology. And that... seems like a pretty big assumption, if human history is any indication.

cmsj 1y ago
The thinking generally would be that while it might take political pressure to initially begin leaving the home planet, once politics has unlocked that capability, commerce will take over. If we were to begin mining the solar system, it unlocks vast pools of resources that would really change things. That said, interstellar travel is still a pipe dream because of the time involved. Without finding a cheat code for physics, it may well be that intelligent life is always trapped in its home system and has to live and die within the limitations of stellar evolution.
- Earw0rm 1y ago
  Vast pools of /what/ though? It seems, at present, that energy is more of a constraint on civilization than matter. With unlimited cheap energy, there's enough material to do most anything we might reasonably want. It's likely to cost $thousands/kg to bring materials back from beyond Earth orbit. There are only a handful of elements valuable enough, and that's if they existed in pure form. Hypothetically, if an asteroid made of pure gold existed, and if a Cargo Dragon atop a Falcon Heavy had enough delta-V to make it there and back with a couple of tonnes, it might break even, but all of this is doubtful. Most valuable minerals are worth hundreds to low thousands of dollars per kg, so you need a launcher that can bring back a ton of rock for $1M - and not from LEO, you probably need to escape Earth's gravity and get back again. The physics and engineering are proven, but the economics? Unlikely. Put another way, you can mine a heck of a lot of Earth rocks with a rocket's worth of kerosene.

mpalmer 1y ago

> millions of years more technologically advanced than us > should be leaving telltale signatures across the sky that we'd likely have detected by now I'm not sure the second follows from the first. What if they're hiding?

soneca 1y ago

I always thought that how far things are in the universe and the impossibility of faster than light travel were enough to explain why life might be abundant in the universe yet we never observed it.

vivzkestrel 1y ago

no matter how advanced the civilization is, proxima centauri will always be 42 trillion kms away. Our civilization in current stage is not even close to 0.1% the speed of light but lets say your advanced civilization goes at 99% the speed of light, still doesnt change the fact they need 4.25 years approx to reach earth. Still doesnt change the fact that unless they have a 1 billion km wide telscope, they cannot reliably tell if earth has life or not. So basically you are asking them to take a shot at coming to the solar system on a 5 yr trip when they have no idea what is found here. Now extrapolate the numbers for the average 100 light year trip between 2 points on our galaxy and you ll quickly realize why we dont have aliens

dash2 1y ago
> Still doesnt change the fact that unless they have a 1 billion km wide telscope, they cannot reliably tell if earth has life or not. How come we’re making progress on this without a 1bn km telescope?
- 986aignan 1y ago
  And even that notwithstanding, they could use a solar foci telescope. It's kind of a pain to orient, but it /does/ give you extreme magnification.
globular-toast 1y ago
If they came here and back at .99c it would be ~70 years "time debt"[0] for them (meaning 70 years would have passed for their relatives back home). [0] Terminology from Dan Simmons's Hyperion. Would also recommend Joe Haldeman's The Forever War for more time dilation themes.
glimshe 1y ago
Where did you get the 1bn km number? I'm asking it seriously, I'd like to better understand how to calculate these things.
- vivzkestrel 1y ago

sixQuarks 1y ago

There is no way civilizations make it past a certain point. It’s so completely obvious, just look at our world. In 2025 we are enabling a genocide while the masses don’t seem to care or even know about it. You think the people that are having these types of atrocities committed against them would think twice about ending civilization as revenge if given the power? What do you think is going to happen with AI? If we can’t stop a genocide, why would you think we can stop civilization ending?

halgir 1y ago

Someone has to be the first. Granted, us being first is extremely unlikely. But the same is true for whoever it ends up having been.

psychoslave 1y ago

Also even if it's low, it's not impossible that human technology actually is the one with the more advanced in its observable part of the universe. That is, if there is supposedly one civilisation with clear advance in technology, it could just as well be humanity.

pc86 1y ago

It's extremely likely that our demise will come before too long. The problem is that "before too long" is on a universal timescale, not a human timescale. Humanity could exist for a million times longer than it already has, expand to other planets in our solar system and even to another solar system or two, be wiped out completely, and on the appropriate timescale we were absolutely "short lived."

throw4847285 1y ago

This is where the discussion, as it always does, silently transitions from science into science fiction. We know absolutely nothing about extraterrestrial life. We can only project our own singular experience onto the rest of the universe. We only have one data point. There is no scientifically acceptable method of induction from a single data point. The possibilities are endless, and are capacity to narrow them down becomes warped by our love of stories and the kinds of art that we have created about extraterrestial life, all of which are in one way or another metaphors for the human condition. There is nothing wrong with saying, "Anything is possible and we have 0 evidence allowing us to narrow it down." It isn't fun, but it's true.

mbfg 1y ago

The thing is we've only been around a tiny period of time, and given the size of the universe, it would have to be an amazingly tiny Goldilocks zone in time to actually notice us, let alone do anything about it.

perlgeek 1y ago

Even if civilizations are relatively common (which, as others have pointed out, doesn't necessarily follow from life being common), the distances involved are really huge. We have some ideas for crossing huge distances, but none of them are really practical. There are ideas for accelerating tiny probes with light sails, but when we manage to send them somewhere with 90% of the speed of light, we have no way to decelerate them again in a controlled fashion. What I want to say is: there's good reason to think that doing anything over 200 light years or so is just infeasible.

jschulenklopper 1y ago

> relatively strong evidence that life, while common, isn't long-lived. https://en.wikipedia.org/wiki/Great_Filter https://en.wikipedia.org/wiki/Great_Filter