Why Alien Life Would be our Doom – The Great Filter

Imagine NASA announced today
that they found aliens. Bacteria on Mars, weird alien fish
in the oceans of Europa, and also ancient alien ruins on Titan. Wouldn’t that be great? Well, no. It would be horrible news, devastating even. It could mean that the end of humanity
is almost certain and that it might be coming soon. Why? Why would the most exciting
discovery of our lifetime be bad? Let us imagine the development of life, from its inception to us today, as a flight of stairs. The first step is dead chemistry
that needs to assemble itself into self-replicating patterns,
stable and resilient, but also able to change and evolve. The second step is for our early life to
become more complex, able to build more complicated structures, and use the available energy
much more efficiently. On the next step, these cells combine
to become multicellular beings, enabling unbelievable variety
and further complexity. The step above sees the species
evolve big brains, enabling the use of tools, culture
and shared knowledge, which creates even higher complexity. The species can now become the
dominant lifeform on its planet, and change it according to its needs. First shy attempts to leave its
planet are happening. This is where we are now. It’s in the nature of life as we know it to reach out, to cover every
niche it can. And since planets have a limited
carrying capacity and lifespan, if a species wants to survive, it will look for more places
to spread to. So the steps above the current
ones seem logical: colonize your own solar system, then spread further to reach
other stars, to the possible final step:
becoming a galaxy-wide civilization. It’s very likely that this is a universal
principle for civilizations, no matter where they’re from. If a species is competitive and driven
enough to take control over its planet, they’ll probably not stop there. We know that there are up to 500 billion
planets in the Milky Way, at least 10 billion Earth-like planets. Many have been around billions
of years longer than Earth. But we’re observing zero
galactic civilizations. We should be able to see something… …but there’s nothing. Space seems
to be empty and dead. This means something is preventing living
things from climbing the staircase, beyond the step we’re on right now. …Something that makes becoming
a galactic civilization extremely hard, maybe impossible. This is the Great Filter. …A challenge or danger so
hard to overcome, that it eliminates almost every
species that encounters it. There are two scenarios: One means we are incredibly
special and lucky, the other one means we are doomed
and practically already dead. It depends on where the filter
is on our staircase: behind, or ahead of us? Scenario 1: Scenario 1:
The filter is behind us. We are the first. If the filter is behind us, that means that one of the steps we passed is almost impossible to take. Which step could it be? Is life ITSELF extremely rare? It’s very hard to make predictions
about how likely it is for life to emerge from dead things. There is no consensus. Some scientists think it develops everywhere
where the conditions are right; others think that Earth might
be the ONLY living place in the universe. Another candidate is the step
of complex animal cells. A very specific thing happened
on this step, and as far as we know, it happened
exactly once. A primitive hunter cell
swallowed another cell, but instead of devouring it,
the two cells formed a union. The bigger cell provided shelter, took care of interacting with the
environment and providing resources, while the smaller one used its
new home and free stuff, to focus on providing a lot of extra
energy for its host. With the abundant energy, the host cell
could grow more than before and build new and expensive things
to improve itself, while the guest became the
powerhouse of the cell. These cells make up every
animal on the planet. Maybe there are billions of bacteria-covered planets in the Milky Way, but not a single one, apart from us, has achieved our level of complexity. …or intelligence. We humans feel very smart and
sophisticated with our crossword puzzles and romantic novels. But a big brain, is first and foremost, a very expensive evolutionary investment. They are fragile, they don’t help in a fistfight with a bear, they cost enormous amounts of energy, and despite them, it took modern humans, 200,000 years to get from sharp sticks
to civilization. Being smart does not mean you get
to win automatically. Maybe intelligence is just not so great, and we’re lucky that it worked out for us. Scenario 2: Scenario 2:
The filter is ahead of us. Plenty of others died already. A Great Filter before us is orders of magnitude more dangerous than anything we encountered so far. Even if a major disaster killed most of us or threw us back thousands of years, we would survive and recover. And if we can recover, even if it takes a million years, then it’s not a Great Filter, but just a roadblock to an eventual galactic civilization. On universal timescales, even millions of years are just the blink of an eye. If a Great Filter really lies before us, it has to be so dangerous, so purely devastating and powerful, that it has destroyed most, if not all, advanced civilizations in our galaxy over billions of years. A really daunting and depressing hypothesis is that once a species takes control over its planet, it’s already on the path to self-destruction. Technology is a good way to achieve that. It needs to be something that’s so obvious, that virtually everybody discovers it, and so dangerous, that its discovery leads almost universally to an existential disaster. A large-scale nuclear war, nanotechnology that gets out of control, genetic engineering of the perfect super bug, an experiment that lights the whole atmosphere on fire. It might be a super-intelligent AI that accidentally (or purposely) destroys its creators. Or things that we can’t even see coming right now. Or it’s way simpler: species competitive enough to take over their planet necessarily destroy it while competing with each other for resources. Maybe there are runaway chain reactions in every ecosystem that once set in motion, are not fixable. And so once a civilization is powerful enough to change the composition of its atmosphere, they make their planet uninhabitable 100% of the time. Let’s hope that that’s not the case. If the filter IS ahead of us, our odds are really bad. What we can hope for. THIS is why finding life beyond Earth would be horrible. The more common life is in the universe, and the more advanced and complex it is, the more likely it becomes that a filter is in front of us. Bacteria would be bad, small animals would be worse, intelligent life would be alarming. Ruins of ancient alien civilizations… would be horrible. The best case scenario for us right now is that Mars is sterile, that Europa’s oceans are devoid of life, and the vast arms of the Milky Way harbor only empty oceans hugging dead continents. …That there are billions of empty planets waiting to be discovered and to be filled up with life. Billions of new homes… waiting for us… to finally arrive. How likely is it that we’ll find life outside of Earth that is similar to us? Well, that depends on how many planets there are out there in their star’s Goldilocks Zone– the area around the star where water can be liquid. Because stars come in all sizes and configurations, this zone is different for every star system and requires a little bit of physics to figure out. If that sounds like fun to you, this quiz from Brilliant helps to break down the maths for exactly how this is calculated. Brilliant is a problem-solving website that teaches you to think like a scientist by guiding you through problems. They take concepts like these break them up, into bite-sized bits present clear thinking in each part, and then build back up to an interesting conclusion. If you visit brilliant.org/nutshell or click the link in the description, you can sign up for free and learn all kinds of things. And as a bonus for Kurzgesagt viewers, the first 688 people will also get 20% of their annual membership. And if you DO find life on other planets, it may be wise to leave them alone for a while.


  1. If humans were instinct and earth water were still alive then I guess human/animal life would come back….maybe don't know I'm not smart

  2. You: virtually everyone discovers this thing that wipes out the entire race.

  3. I feel like if we are here at this point in time and we know there’s 1 billion stars out there and many more like our galaxy the possibilities of there being life has to be true because this one just makes sense how are we here today and there’s billions of other life supporting planets like it just makes sense that they would have to support lif

  4. Why would it matter where we stand, if it's already decided where we are going ? Finding or not finding life on Mars would not change our position in the filter.

  5. "Maybe there are runaway chain reactions in every ecosystem that once set in motion, are not fixable. And so once a civilization is powerful enough to change the composition of its atmosphere, they make their planet uninhabitable 100% of the time. Let's hope that that's not the case."

    Narrator: It is.

  6. Idiots there are no such things as aliens UFOs sasquatch dinosaurs Santa claus Easter bunny tooth fairy just humans God and Jesus heaven and hell are real

  7. What if their isn’t a filter and every form of advanced life gets wiped out by their respective sun before they can be discovered

  8. Few problems with the filter in front theory: 1. It assumes that ALL intelligent life that is or even more intelligent than human life, WILL perpetually use up all of its resources until its environment is so exhausted that for life to continue it MUST find new uninhabited environments to support its perpetual expansion. This an absolutely absurd anthropomorphic assumption. We havent sufficiently evolved emotionally as a species (well, most us anyways) to learn how to make the most of the resources on our home planet to survive without needing to compete. We lack the emotional, not technological, capacity to move past this scenario. It imposes standards of human morality on the concept of intelligent life that may have already move on to the next filter of evolution, maybe even with surprising ease in comparison to human beings. It's reasonable to believe that this may or may not be the case, but its absurd to believe that this is always, or even mostly, the case elsewhere. We really aren't that far away from achieving a civilization with the technological capacity to become the perpetual dominant species on our home planet for millions of years, well long enough to conceive of intergalactic travel as very real possibility for our species once the sun has exhausted all of its fuel. Yet, we lack the emotional capacity to stop killing ourselves in the name of resource hoarding long enough to achieve this vision of humanity. 2. It makes another grand assumption that's particularly anthropomorphic as well- perpetual existence good, finite existence bad. Again, most of us havent evolved sufficiently enough (or perhaps on this issue we have actually de-evolved) to have the intellectual maturity and honesty to confront the very real possibility that our every day experience of "reality" as we know it through our consciousness may be some, mostly or even entirely illusory and that higher levels of reality might exist alongside what we can hear, see, touch, smell, taste and rationalize mathematically. Given enough time (which is looking less and less likely) our species very well might just learn to leave the dark cave that we're currently living in and transcend the fear of death with a better refined and more accurate understanding of reality. With this, we may be the first form of life on earth to DECIDE to allow ourselves to go extinct. 3. The video presents a very narrow view of just how large the known cosmos actually is. Given the sheer size of the cosmos, its hardly surprising that even if intelligent life were extremely common we would not have already made contact with it. 4. On the flip side, it also assumes that other intelligent beings in the cosmos havent already made contact with our species and that they havent tried to guide humanity towards our next phase of evolution. In fact, there is an entire series of books derived from human art, culture and eye witness accounts, handed down over the span of mellenia, that insist upon that very notion- that there is a form of intelligence that is so vastly superior to human intellect and evolution that it created the entire cosmos, including all life on our planet; that it's intelligence transcends our understanding of reality; that it permeates every facet of reality, because it is fundementally all that is, was, and ever will be in the cosmos, including humans; that it is fundementally, but not entirely, knowable; that it communicates directly and indirectly with humans through our conscious and unconscious experience of the cosmos and indeed through our very nature as human beings; and that it understands the plight of the human race since it made a choice directly inhabit the consciousness of the thing it created as a message of love and good will towards all of humanity. Now…. wouldnt that be nice? I suspect most of you will spend more time postulating conspiracy theories about flying saucers and the government. Because that's the trendy thing to do these days isnt it? Again, I'll use the word de-evolution here to describe our behavior in the year 2019.

    But what do I know? It's all just conjecture and postulation isnt it, everything that we've discussed here? Sure it is. If that's what you need to get to sleep at night, a false sense of knowledge and understanding, I wont even try to rob you of your security- it wouldnt work even if I tried.

  9. 500 billion planets in our galaxy. 10 billion of these resembles earth.
    That is quite a difference.
    So prehaps our planet is the only one that host an intelligent civilization that has invented radio sequenses to transmit.
    Maybe some where in a far of plant their actually is intelligent life They just have'nt got the same advance technology as us.
    Their for it's our duty as a planet civilization to go out explore and 👑conqu🔥 …. hrrm show them our way of freedom and peace ⚧

  10. The Great Filter is nonsense. Firstly, there is nothing in science that suggests that there is "one thing"(the filter) that would allow life to propagate. Secondly, just cause we have not observed galactic civilizations doesn't mean that there are not MANY. Perhaps there is a "no fly zone" set by some galactic bosses that tell all other life to avoid non space fairing planets. SO MANY other possibilities, this is just the most obvious

  11. Maybe the great filter is space travel/colonization itself

    Maybe intelligent species are all stuck on their home planet with no way to spread, eventually dying out due to random reasons over the course of millions of years – some got fried by their star going supernova, some got hit by freak gamma ray bursts, and yes some wiped themselves out with nuclear war, etc

  12. Why would intelligent life be worse? Like alien civilizations or smart animals? Cause if you mean ultra advanced civilizations wouldn’t that prove that we passed the filters? If you mean our level civilizations then I get it though.

  13. The assumption that other alien races would think like a parasite from Earth is a massive oversight, and completely deludes any findings based on this assumption. You should be smarter than this…

  14. But, as they said, we have no clear way of knowing exactly how rare life in the Universe is. Discovering new life could simply be an incredibly lucky find. The presented theories are logical, though they all hinge on the fact that we cannot see traces of intergslactic civilizations on often outdated images. We have no way of knowing whether or not it would even leave observable traces. So maybe discovering extra-terrestrial life could be bad… according to this theory.

  15. Meeting another life form would be life changing. Imagine what they could give us. Maybe this life form has the technology for light speed or teleportation but to them it's a very simple formula. They'd trade it with us for something like beverages such as soft drinks and whatnot. We really don't know but I hope it'll happen someday. Hopefully they won't be hostile and destroy us all ._.

  16. I think we are just located in s special area that if a civilization is advanced to reach us, it has already became self-sufficient and evading us becomes pointless.

  17. Imagine in the future this would either be a bible if aliens were hostile or be banned because of xenophobia if aliens were nice

  18. Haven't found life outside Earth: There must be a great Filter that stops life from becoming intergalactic.

    Finds a lot of other lifeforms in other planet:
    This must mean that this Great Filter is ahead of us, and we'll all die.

    What? Wouldn't finding many planets with life DISPROVE the Great Filter Theory?

  19. If technology is a trait of intelligence, i wonder how many times ai has ended civilizations. Strangely, ai is natural in the sense that we are nature. Anything produced by nature must be nature itself.

  20. How long do you think caveman/cavewoman sex lasted? One minute?

    Ancient-man: Hurr-durr-ooaa-ooaa (sex noises).

    Ancient-woman: Huuuuuuuuuuuuuuuuuuuuuu (sex noises).

    Ancient-man: Huh-huh-huh (sleeping).


    But seriously, I think so many things are filters:

    – Life [existing].

    – Our kind [surviving].

    – Our kind 2.0 surviving.

    – Our kind 59095475375246665875547537155642542565824356.14567585753t63737682246543 surviving.

    – [Communicating] with each other.

    – Succeeding in [space entry].

    Where we are now…

  21. There also could be a third option.
    There can be a reason why intelligent live is not visible to us. It can be because expanding to other planets or solar systems is not the expantion aliens used. What if:
    1: Time can be discovered as a dimension instead of a fixed point
    2: what if there is a 4th dimension which can be much more interesting
    3: What if we are in a simulation?
    4: What if living in black holes are much more interesting?
    5: What if making yourself smaller is the option instead of expanding.
    6: What if the meaning of life is something thay can be discovered and has to do something with this?

    These are all influences that doesn't necessary fit in one of the filter options

  22. The funny thing is everything is digitized from our era onwards. If everything works out for us imagine someone in a colonized solar system in 5000 years reading your comment on this video.

  23. I think I found what is the great filter. It might be wrong. I have a bad english so sorry for misspelling. So, the great filter is life. When life is created, its only purpuse, to make more of it, so making more and more DNA. This works perfectly, until a point, where life evolves so much, that breeding, or making DNA isnt the first purpuse. This happens at the moment too. If you want to be perfectl efficent, you should breed with everybody, you can. Or you couls duplicate urself, but we cant do it. Cells, are almost perfectly efficent, because they are making more DAN a lot, but viruses are even better. They duplicate very fast, and they are the perfect form of life. Duplicating DNA for ever, and disableing other life. So, if a spieces stop not doing anything else but making more DNA, its unefficent. And it will evolve, and make less and less DNA. It could be good, because at a point, the lifeform will reach a stage, where it can make a lot of its own DNA, and do other stuff at the same point. But sadyl, I think this will never happen. So, we are making less and less DNA. We wont stop making DNA, bacuse we destroy ourselves before reaching this point. But this means, evolution is more like a disease at a point, than advantage. But, if we think from an other point, the purpuse of life is destroying itself. I'll continue in an other comment.

  24. Why finding life on other planets would mean that the filter is ahead of us? Why can't it mean that we are both past the filter?

  25. The great filter will always be in front of us. Because we made the filter even exist. Because the great filter is our ignorance. Climate change, political warfare, etc…we will always be the greatest threat to our own being. The more advanced our civilization gets, the larger the weapons get that we point at ourselves.

  26. Its so obvious,… life does not allow absolute control!
    If you solely let Mind to rule…things go mindlessly eventually.
    Often times, it is too late to listen to Heart.

  27. The only it would be bad news, would be that the elite and religious fanatics would lose control of the masses.
    As soon as those in control realise that they eventually have to let go, the better

  28. So huh, tell my why exactly it is relevant that the "great filter" is behind us. The only thing important for our common survival is the greater filter that is ahead of us. Let's analyse all the potential filters that could stop us and think about how to escape the traps we have to avoid in order to go onto the next ladder of evolution.
    The potential of surmounting thoses traps is there, only humanity has to realize the chances are slim and that it will pretty much require an evolved human state to reach there.
    Let's define what that evolved human state would look like and set the change in motion.

  29. 4:04 THE INSTITUTION OF OLD HETEROSEXUAL MARRIAGE. In this case women would be the mithocondria.

    How curious it is that we all inherit our mithocondrial ADN from our mothers and not our fathers!

  30. Did no one consider that there is life and they just have technology that makes them invisible to our technology.

  31. Before I even watch the video I’ve always thought that coming into contact with aliens would be like what happened to the native population when the Europeans came to the new world in regards to disease

  32. My hypothesis for the reason that we can’t see any civilizations on far away planets, each light year in space is equivalent to a year when looking at the surface, for example: a planet with an alien civilization but It’s 4 billion light years away, with a telescope we would see what the planet was like 4 billion years ago before that civilization, like if you were on like Pluto or something let’s say that’s 60 million light years away, they would look with a telescope and see dinosaurs on our surface

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