Why alien life would be our doom: Kurzgesagt – In a Nutshell video

My favorite personal explanation for the Fermi paradox is that we’re the first, or at least part of the first generation of technologically advanced civilizations in the galaxy, perhaps the whole universe.

This seems to go against the Copernican principle – “Let’s not assume we’re a special case” – but in the real life, people do win the lottery despite it being immensely unlikely that any particular person does that. The universe is now about fourteen billion years old, ie. roughly 10^10 years old. The age of starbirth – the stelliferous era – is projected to last for something like 10^14 years, or around 100 trillion years. If so, we’re living in the first one ten thousandth of that span. That means we’re already living in a privileged part of the history of the universe.

I find it very easy to believe that the universe a trillion years from now will be one teeming with life, and shaped by the actions of our descendants and whatever other first-generation civilizations there may be out there.


Sure, I mean…maybe they all live on small, hyper-efficient ships, exploring and observing, and maybe helping as needed.

Colonies are a solution to problems that better tech and efficiency can solve too.

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Yeah. Interstellar travel is really fucking hard. When even science fiction authors increasingly tend towards the idea that sending people outside our solar system breaks suspension of disbelief, it raises the possibility that there’s intelligent, tool-using, interstellar-traveling life out there - and there’s no obvious evidence because at best they sent out a few tiny probes that are never going to survive/get noticed. Though when you add in that our own technological civilization, crude though it is, has been built up in a completely non-sustainable way, it potentially further shrinks the possibility of any sort of interstellar communication/travel.

And the resource cost to get there would be so huge that it raises the question of whether it could even theoretically be worth it.

The idea that we’d send human beings to colonize another solar system is also inherently problematic because we couldn’t live there. We’ve been optimized by evolution to live on Earth (and under recent conditions, no less) - anywhere else is sub-optimal at best. An exoplanet either has no life, in which case it’s uninhabitable (if nothing else, it has no breathable atmosphere), or it does have life and the odds that it would be compatible with our own is exceedingly unlikely (if the local micro-organisms don’t get us, the very building-blocks of life there might cause anaphylaxis on contact).

We only have one data point for the development of sapient life, so we have no idea how common it is, but we do know how much energy and time it would take to get anywhere, and that makes it something of a non-starter.

We don’t know that, though. Part of Drake’s equation were the questions of how common planets were, how common Earth-like planets in habitable zones were and how common life is. Turns out that Earth-like planets in habitable zones are pretty common. It could be that life very readily springs up on any planet that’s habitable, even if it’s just micro-organisms. Either option isn’t so great for aliens wanting to come in as colonizers, though - you have the horror of colonialism and/or the difficulty of living on a planet that’s not habitable.

It’s a lot easier (and more theoretically feasible) to create life that’ll live on a planet than try to recreate the Earth on another planet to the point where humans can live on it, though. Neither option works very well, however. Presumably one is sending a minimal starter kit, i.e. embryos to grow. Who raises those children, for instance? Some human-equivalent AI? If you have human equivalent AI, then why bother recreating humans? (Etc.)

I love Kurzgessagt , but I have one major gripe with this video. It presents the Great Filter as the only possible solution to the Fermi paradox. That’s speculative, but it presents it as an a priori fact, which is misleading. Still a great video, but Kurzgessagt is normally more diligent than to make an error such as that.

Interstellar distance alone cannot be the Great Filter. Even if it takes millions of years, and even if the spread is at 1% light speed, an expanding lifeform has had time to swarm the galaxy many times over in the billions of years since supernovae produced enough heavy elements for complex chemistry.

Moreover, once eukaryotic life emerged on Earth, the subsequent steps took much less time than the span from prokaryotes to eukayotes. Multicellular life independently evolved an estimated 46 times once more complex cells were possible. This is why the video proposes eukaryotic life as a possible past Filter. It’s therefore possible that the relative rarity of eukaryotic life and the need for heavy elements to make evolution as we know it possible means Earth really is the first to planet to get there. I myself am skeptical of this for the simple reason that although symbiogenesis, the merging of prokaryotic cells, only appears to have evolved eukaryotic life once, other organelles also appear to have been integrated through the same process. If it occurred more than once on Earth, that casts doubt on its Great Filter candidacy.

Once a species fills that niche, none other can, unless that one artificially engineers others to join it, either Planet of the Apes style or David Brin’s Uplift style.

Then the question is whether their innate biological drive to expand as much as possible can be reigned in by the lifeforms themselves. The argument is not that lifeforms necessarily always want to expand, but that there’s a biological tendency to expand which, given enough time, the lifeforms will follow. For a civilization’s values to overcome that over a span of history is one thing. For it to overcome it indefinitely would be different. Then again, other lifeforms may not think anything like humans. For example, perhaps their memetic evolution has somehow totally overwhelmed their genetic evolution. Perhaps it even will for us eventually.

This is the explanation I favor, with the understanding that all explinations highly speculative. Most of the galacy’s volume is not a hospitable niche for life evolved in the “Goldilocks” zone of a star system far enough out from the Core not to be devastatingly irradiated. Any life that evolves from life as we know it may be quite common but so energy efficient and utterly alien to us that we have yet to learn how to search for it. And if Earth is under active quarantine for whatever unimaginably alien motives, we probably have no chance of ever finding it at this stage in our development.

Only assuming planet-optimized travelers. Debris traverses the galaxy all the time. If space-optimized life can evolve from planet-optimized life, then it’s logical to conclude it has a decisive evolutionary advantage and thus if any life can dominate the niche of deep space, it will not be the planet-optimized progenitors.

“Space is big. Really big. You just won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist, but that’s just peanuts to space.” ~ Douglas Adams

Perhaps in the sense that we “enslave” paramecia, and we’d have about as much chance of influencing the outcome as the paramecia do of manipulating a lab tech.

If it’s obeyed with anything like the fidelity of the Federation’s explorers, we’d have been contacted five times by the end of season one. :grinning:

Why would any lifeform that could seed interstellar space with its progeny stop before swarming the entire habitable zone of the galaxy? This seems far less likely than it either stays at home or spreads as far as it can. And once you can seed your neighboring stars, the rest are only a matter of time, of which there’s plenty once past any Great Filter.


Were already within a stones throw of AI that could self replicate and spread throughout the universe.
I never see examples of the Drake equation or the Fermi paradox that take this into example.
Surely other civilizations if they have got this far would have done this too. So either they’re hiding or its only us so far.
Were always discussing this as through life from a planet is the future but its far more likely to have evolved way beyond its original biological limitations.


It’s a Vogon Constructor Fleet clearing the hyperspace bypass.


Yeah, for something that turns out to be a long-form commercial for a website offering to “teach you to think like a scientist”, this video strings together a whole lot of tenuous guesses with some very unscientific reasoning. It’s all “the only possibilities are [short list of things the author has seen on Star Trek], therefore X”.

The only scientific answer to the question of alien life is: We Don’t Have That Info. Just because science fiction has “science” in the name doesn’t mean you can use it as a backup when science doesn’t give you answers.

IMO the silliest assumption is that if life persists long enough, it would necessarily spread through space. Sure, it’s maddening to think that there’s infinite stuff out there and we don’t get to visit it. I wouldn’t be surprised if other life felt the same way. But is it so maddening that we’ll ever find it worthwhile to overcome the titanic difficulty involved? To me, it’s easier to believe that we’ll just spend a million generations gazing longingly at the stars, and wishing we could go there, but then eventually returning to our day jobs. Poignant but believable.


Somehow all this reminds me of an s-f short story I read in the early 60s. Rather jingoistic but still amusing. The premise was that the secret of interstellar travel is really quite basic, and most galactic civilizations discover it in the early stages of their development. However during its technological development humankind just happened to have missed it. Therefore when aliens finally come (to present-day earth) and invade, every other aspect of our technology, especially weaponry, is so much more advanced than theirs that we kick their asses and take over the universe.

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" In a Nutshell video says there are 10 billion earth-like planets in the Milky Way…"

Oh, are there? Really? Same sun, same metal spinning core, same electromagnetic field, same tilt, same water composition, same distance from Supernovae, same water, same elemental distribution, same large moon causing tides, same history of almost but not quite cataclysm, same evolutionary randomness, etc etc etc? Because that is what we have here, and it is all important.

Maybe it might be better to say these “Might be” rather than there are “are”. Or, maybe it would be wiser to say it is almost impossible that another actually exists? That the odds are infinitesimal?

" … If they have or had life on them they should have colonized the galaxy."

Sorry, but that is a very difficult pill to swallow. There appears to be NO evolutionary advantage to intelligence. Not only do we see this in eco studies on other species, but we humans have been here a really short time. And we already have a history of major societal annihilation. And that was before we started burning gigantic amounts of carbon, created bio-terror weapons, and stockpiling nuclear arms. No, life may not be so hard, but sustained intelligent life? Very risky proposition.

Dinosaurs were here for 160 million years, and it took a comet to wipe them out. We have been here about 1/1000th as long and we will be fortunate to make it another 200 years.


This one hasn’t been posted yet?

I am disappointed in all of you.

Agreed. Other sub-human intelligence level life has lasted a lot longer than we have already :slight_smile:

Sustained intelligent life must be: life but not as we know it

Assuming that all intelligent life will spread across the cosmos once passing a series of filters is a big assumption.

One major point in favor of the ‘filter’ hypothesis is how dangerous anything even vaguely useful for long distance travel would probably be.

Barring some sort of very carefully nerfed hyperdrive nigh magically useful only for transportation(not even telefragging); anyone who can travel more than a handful of light years in usable time has access to energy on a scale that makes thermonuclear war barely distinguishable from background noise. Anyone who has that is either very stable or very on fire.


Well there’s lots of potential reasons. One is that the whole matter of time thing isn’t trivial. Space is big. Really big. You just won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist, but that’s just peanuts to space. So, yeah, if you can get to a neighboring star, there’s no good reason why you can go to the next one and the next after that. It could take billions of years before any two civilizations run into each other given the vastness of space and the amount of time it takes to expand through it. From a practical point of view, each colonized planet is probably going to have to build its own space program in order to expand further. Even if you can get from planet A to B, that doesn’t make A to C feasible. Likely only people from planet B can get to planet C, and so on. Some planets may be perfectly habitable, but lack the mineral resources needed to expand further out.

I’m also not sure I like the idea of a filter. Right now we can destroy the entire planet with nuclear weapons. Even if we expand past to other worlds, we may never get over that. A nuclear war wouldn’t put the whole species at risk, but every individual world would still stand a chance of destroying itself. Once a world destroys itself, none of the worlds it had access to are accessible unless someone colonizes that world again.

Finally, a single species, galaxy spanning empire isn’t really possible. Each world in effective isolation, and communications lag of years between even close planets, means that a unified government would be impossible, and over time humanity would evolve in different directions. So I guess turf wars with aliens are likely, it’s just the aliens are actually distant relatives.


I see. You’re working from the viewpoint that planet-optimized lifeforms would go to other star systems for other planets like ours. I’m extremely skeptical of that premise. I think whatever builds an interstellar culture would and/or will be engineers/evolved specifically to thrive in deep space, and will probably avoid settling on terrestrial planets. I doubt they’d govern themselves the same way humans do. Our styles of government emerged to work in a very different environment. Basically, I think the whole traditional space opera notion of a Galactic Empire is a human fantasy of us imagining we can colonize the galaxy. In reality, if anything descended from us crosses the sea of stars, it will have little in common with our Earth-optimized bodies and will probably eschew our terrestrial forms of government.

Space is simply too hostile to life as we know it for us to have any real chance of out-competing life optimized to live there. We might be able to send some human colonies to a few stars over millions of years, but we’ll be left in the interstellar dust by decedents of ours who don’t need to lug along a sizeable replica of their whole ecosystem.

As might be noticed, I’m deliberately avoiding saying machines because really the human body is also a machine, and our own machines to date aren’t much more suited to deep-space than we are, so I’m just saying whatever lifeforms we give rise to one way or another which are adapted for life in deep space and slow interstellar travel. And then I’m extrapolating that to any other planet-evolved alien life that preceded us in the galaxy since they too would have the same thing holding them back.


Well, yeah, I was, after all, responding to where you said

And you’d also mentioned seeding nearby stars, so… yeah, deep space wasn’t on my mind.

That being said, the chances of having wars over territory in deep space is even less likely than planet based expansion because… well space is big. If two species are both attempting to colonize the same types of planets, they’re far more likely to encounter each other than two species in deep space. If you’re way out in the black, you could basically be right next to another species and never know it, or even have overlapping territory and still be too far away to ever actually notice the other. You also hit the same issues of distance. Another species across deep space is still going to be cut off from other members of the species due to distance. If it’s a species that is self engineering, it’s even more likely to develop into something unrecognizable. The idea of any one entity spread out over much space isn’t workable. Spread out too far, and you get lots of different species, distantly related.

So bringing it back to the idea of if colonization of space has the same issues that Earthly colonization does, I still say it’s a firm no. If we colonize other planets, we are unlikely to run into conflict with other beings. If we colonize deep space, we’re possibly even less likely to run into other beings. The idea (not an idea advanced by yourself, but the original point I was getting at) that space colonization, assuming it’s feasible, which it really isn’t, is comparable to the past evils of a colonial mindset seems flawed.

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Of course there are many other alternate but fun theories to the Fermi paradox.
But those alternatives are rarely considered, or even mentioned, they’re almost taboo… o_O

The main theory from left field is : that -we are- a colony.
Albeit a genetically engineered and hybridized colony.

As to why we don’t see any aliens; well that’s another set of guesses entirely. The most common answer is that they don’t want to be seen, and they have the means and technologies to stay hidden.
Another popular answer, is that earth has been quarantined for whatever reason. Perhaps as a result of our own violent actions, or because of a prime directive of theirs, or perhaps earth is in limbo following a territorial dispute, or perhaps we are left to our own devices as some sort of experiment - who knows.

My mistake. By deep-space I meant beyond the orbit of the homeworld. Sorry for the misunderstanding.

Perhaps. Evolution, natural or otherwise, occurs when there’s an open niche, whereupon it speeds up until there is something that is just good enough to occupy that niche. While I suspect different sorts of life would develop to occupy different niches (near stars, gas giants, asteriods, dwarf planets, in and out of various strength magentospheres and ambient particle conditions, and quite possibly constructed habitats, computing substrates, ect…), the frequency of evolution would depend on the stability of the occupied niches, which is hard to speculate on since we have zero data on space-adapted life. At any rate, I don’t think that one lifeform would monoculture the galaxy. Just that one successful origin point of space-optimize life could swarm the galaxy, evolving as needed as it went over eons, but generally reducing the available virgin matter in the galaxy available for other aliens to independently naturally evolve.


On the motivation for hypothetical interstellar travelers, I think it pretty much has to be ideological. Mere profit motive is not feasible, barring some kind of FTL or really long-term thinking, very stable society. But a religious / philosophical drive to see and learn whatever is out there, or to spread life across the galaxy to make the universe a more complex and therefore more interesting place, sounds entirely possible to me.


I think interstellar travel at a sizeable fraction of light speed is quite feasible. There are solar sail technologies which could act as a motor and a brake. But they have to be light. We could make molecular level carbon circuits which would be extremely light, energy efficient, and radiation hard. Indeed, it may be easier for craft like that to go to the nearest stars and come back again, rather than try and beam information on what they found back to earth.

How to we get humans there? It would be easier to take human genetic material than to take living beings, even in suspended animation. The Japanese are working on humanoid robots to look after the elderly, so it is not a huge leap to suggest they could act as surrogate parents. All we need to take is the tiny maker bot with instructions to make the colony and then the people to live in it. I am not saying this is an ethical thing to do, but it is a better option than shutting two generations of families in a generation ship so the third might see their possibly barren destination. We don’t have the technology, but only 66 years separates the Wright brothers and Apollo 11.

In the sixties, everyone felt that going to Mars and Venus, then the outer planets, then the stars was inevitable (remember, we were supposed to be out at Jupiter by 2001). Now, we are wondering what the payback is. We aren’t going to come back with gold, tobacco, and slaves. We aren’t going to stay there, and spread the Empire. By the time the third generation gets there, they won’t be ‘us’, they will be ‘them’. And we haven’t been back to the Moon, since.

PS: I don’t buy the idea that we need to spread humanity to survive. In the very long-term, yes, maybe. But none of the giant meteors killed All Life. For humans to go extinct, you would have to kill all the ones in bunkers in Switzerland, North Korea, and North Dakota. Mankind has been reduced to very small numbers before, and we are still here.


Perhaps the most interesting take on this is Iain M. Banks’ novella The State of the Art, which portrays a Culture ship investigating Earth in the 1970’s, and deciding it would make a experiment to test if nonintervention actually works.

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