Why Alien Life Would be our Doom – The Great Filter

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.

Dereck Turner

92 thoughts on “Why Alien Life Would be our Doom – The Great Filter

  1. Kurzgesagt – In a Nutshell says:

    There's brand new stuff in the Kurzgesagt Merch Shop. Check it out here: shop.kurzgesagt.org

  2. AleXX says:

    I love these theory’s a lot they are cool

  3. Sasquatch94 says:

    Why are we fulfilled at only being galactic species (: "our final stop: a galactic species")?
    We should and eventually need to go further. So why no intergalactic species? Yes reaching them is actually a problem, still theoretically unfixed. So maybe intergalactic isn't a good one since I don't see us reaching another galaxy while the galaxy and us are moving at near light speed away from each other… a universal species then? That could be quite fitting.

  4. Oscar Moreno says:

    You guys should start tagging all the presidents of each country in your videos.

  5. Kr4yw says:

    What if all intelligent life travels to the future past the great filter?

  6. MayTheGamer 12 says:

    Basically either we must panic because something is coming or forever be alone.

  7. Thiago Weslley says:

    This remember me of the Dwemers from The Elder Scrolls. Their search for advanced technology only lead them to their own destruction.

  8. Robin D says:

    Ken and Pewdiepie when they play minecraft: 1:15

  9. Jason says:

    Species sounds like a disease

  10. TTV Caliber says:

    what is the exact definition of life??? there might be life somewhere in our solar system but we don't recognize it

  11. n2dasecend says:

    B I G B R A I N

  12. TheGreatYukon says:

    I think it's a mistake to assume that life will want to spread itself out. Even today, there are people people (at least, I'm of this opinion) that believe we should work towards creating indefinite lifespans, and slowing or stopping breeding. Need more creativity or fresh new ideas? Transhumanism and post-humanism. Another species could come to this conclusion as well, instead of creating NEW people, just change what you have so you have better people. Any civilization that goes for the path of advancing their species like this, I think, won't breed as much. Why spread out across the galaxy? It's wasteful.

    Yes more minds make better ideas and cooler stuff, but as it stands our civilization is massively inefficient. So many people lack the opportunities they need to make something of themselves. Mental illness is a serious problem, holding back lots of people from being motivated and useful (I understand that part a bit too well). Make more efficient use of what you have, uplift those who are poor from poverty, stop this system that relies on perpetual growth and the existence of underclasses. Ramp up education, there's lots we can do, none of which necessarily requires that we keep breeding so long as we can deal with the change in our economic system.

    So, why haven't we met anyone? Our current ideas for civilization are primitive and silly. Why spread out across the galaxy? You can just simulate it. Why keep reproducing? You can just make the people you have even better. As for an alien civilization coming to our planet for its resources, if they can reach us I don't think they'd need to do that. Plenty of planets likely don't have life like us on it. Maybe I'm just being hopeful though.

  13. Bryce Alexander says:

    One great filter not mentioned. The difficulty of traveling great distances at sub light speeds. It may not even possible to reach FTL, so serious civilization expansion may be severely hampered by distance.

  14. The Father Of The Bassline says:

    7:32 is he smoking a bong?

  15. Nicholas Pandiscia says:

    The great filter is simply just the Reapers from Mass Effect.

  16. Peter George says:

    1:15 Perfect description of pewds

  17. Oh Yeah yeah 0820 says:

    BIG BRAIN 1:16

  18. aye126 says:

    Umm. Have you ever seen futurama? The aliens would be great.

  19. DozTalks says:

    @what if stole your video…like word for word

  20. Stephano Jeong says:

    Kurzgesagt's favorite words: devastating, dangerous, horrible, doom, alarming…

  21. Cengiz W [Fart Poop Gamer] says:

    Didn't come for an existential crisis but ok

  22. DCode [ ‎ ‎ ] says:

    Greed will decide the ultimate fate of humanity , I can predict that one day when our time is up a space ship will be made to search for a habitual planet and it wont cost a penny and that will be the moment we realise that money has always been one filter we had to overcome to reach out….

  23. Maartje Ament says:

    y'know guys that our species will die out and it's better for the planet if we'd all die so i hope the filter is ahead of us

  24. Skyfly says:

    Ehh… They already found fossilised bacteria on some asteroid and Mars. Nice? I guess

  25. tbhvivian says:

    What if us spreading is the end of human altogether

  26. Stranger No one says:

    Well, This is depressing

  27. Choco Prince says:

    But what is this great filter

  28. Yuri ' says:


  29. Daddy Dreadful says:

    Who says there is only one great filter? Maybe there was one behind us, and there’s another in front of us.

  30. K1ngcy 1 says:

    The impossible Barrier is the big bang

  31. Shadowww says:

    1:15 Yep big brains thats me

  32. Pierre Ghislain says:

    The idea that we could leave this planet and colonize others to perenise humanity is foolish. To find a planet remotly like earth would mean travelling for at least several thousands of years. To live on a closer planet like Mars would mean a life not worth living and totally depending on technology (which, lets face it, we will screw up at some point). There's no back up guys… This is the one.

  33. SuperToku 64 says:

    This never really told me exactly WHY aliens would be bad besides wars and stuff.

  34. MR DELORIAN says:

    I heard from another video, (or someone else) that alien discovery’s would cause a war on religion and lots of conflict in religion, since (I’m paraphrasing) it’s said we’re IT and we’re unique. Thought this would be an interesting add on.

  35. Son Ken Sama says:

    Maybe the great filter is the discovery of

    dAnK mEmEs

  36. jan exptm says:

    this has many assumptions, some of which are simply false.

  37. Elcio Loch says:

    I don’t wanna dieeee!

  38. JSauce the furry hunter says:


  39. Rich Waffle says:

    so……am i gonna not see another planet?

  40. Hans Castro says:

    The "great filter" will only simply drive selection. It's just like how it was when people first crossed the oceans. All we need is genetic diversity.

  41. chairmanofrussia says:

    They actually did a simulation of alien civs and climate change/overpopulation. Only 1/4 civilizations actually survived. The rest has a population crash of some sort.

  42. Huey Ly says:

    There is a 3rd possibility. Events and technology beyond the great filter is unobservable by us. Just as bacteria, cells, mitochondria are unable to "comprehend" the existence of the human world, we may not be advanced enough to to observe or detect the reality beyond this one. I think that's a more comforting thought than the two scenarios presented.

  43. Brien Sherman says:

    I can't help but be of the opinion that we haven't detected alien life because any advanced space faring civilization would have discovered how to communicate faster than light, otherwise it makes a galactic empire that spans tens or thousands of light years very difficult to manage. And because we have no way of detecting faster than light communication signals, it doesn't mean that no advanced civilizations exist, we're just too primitive to detect their signals.

    So rather than there being a great filter ahead of us, or there being a great filter at all, we just need to continue to advance as a civilization before we will be able to develop the technology in order to detect other advanced space faring civilizations with galactic empires tht span tens or thousands of (or more) light years.

  44. Arsalan Hashemzade Sarraf says:

    all just cartoon nonsense
    secular interpretations

  45. Random God says:

    why not both

  46. Phenomenon Lobster says:

    if you die you recarnit

  47. Peter D says:

    Yeah, but if we end up discovering lots of extant civilisations, there's no great filter. Am I missing something?

  48. TheDonekyYT says:

    Oh yeah this is big brain time 1:16

  49. Colin Chan ET says:

    Wait, but will there be a "Supreme" age?
    Put simply, we advance so much that we turn ourselves into "perfect" robots.

  50. Mehreen Amir says:

    but wouldn't it take a lot of energy and time to move from solar system to solar system?

  51. hamzy hagjer says:

    Eath going to die
    Human's: Lets make more weapons

  52. Lee Hong Jin says:

    First we gotta invent new forms of power. Oil isn't going to get us very far, and we won't find oil if there are no other living beings on other planets.

  53. TacSav253 says:

    ,,WHY I THINK, 😏

    All your history stinks

  54. Jasmine Lav. says:

    What if discovering another species is the key to surviving this (theoretical) Great Wall? This theory assumes that survival is a zero-sum game where one planetary species gets to inherit the universe, or all of them die. So what if finding another living planet and learning to live cooperatively (like the mitochondria you mentioned) is how we survive what's to come, and the other planets that died are the ones who didn't locate anyone else in time? This is assuming that learning to live symbiotically with other species isn't the "Wall" itself, and other aliens died off due to a mixture of self-destructive competition and warfare.

  55. Greninjaplays says:

    0:09 AVENGER ENDGAME (titan + Thanos home planet)

  56. Mat Mat says:

    It would be cool if it turned out that we are the only Life form and something basically just gave us the whole universe to do whatever in

  57. Dick Head says:

    7:32 didn’t know aliens hit bongs

  58. Nebu says:

    Invader Zim doesn't belong on Earth.

  59. Danny Goler says:

    Wouldn’t finding advanced civilizations mean we have finally figured out how to see them, VS meaning there are almost no civilizations that survive?

  60. Armando Granado says:

    All opinion

  61. Ctrl Alt Rmx Music says:

    It seems logical to conclude that life on Earth is more of a controlled experiment to explore how the dominant lifeform man interacts with and treats all living things that inhabit the planet including Earth itself. So our world is a test zone of sorts making Earth the only planet to show signs of life in the galaxy. Much like a prototype before a mass produced final product.

    I believe that humankind cannot safely move beyond the borders of our world because we simply are not allowed to. And our track record as a dominant species shows that we have become a bit parasitic to our environment.

    So other worlds are not open to us because we would lay waste to any other planet we came in contact with and destroy the life sustaining capabilities of the entire galaxy eventually.

    Feel free to disagree though.

  62. kittykatBflat says:

    I don’t has an understand.

  63. Joeri Spek says:

    The great filter could be about controlling nuclear power. Since many great minds thought that once we'd control nuclear power there was a bigger chance that we'd destroy ourselves with it than actually keep it in check.
    It may be because we're such social animals that got us through the filter

  64. Maulik Bagada says:

    What if there are two great filter…. Just saying….

  65. Jorge Martinez says:

    Maybe I am missing something but, as interesting and logical as it seems, I see a fundamental fault in the logic. So they say that if we don’t know of any alien civilization is because, either we are the first one, or we aren’t but all previous ones have died due to a “great filter”. So far, ok. Then they say that if we now find an alien civilization, the first explanation (we're the first) is obviously wrong, so the second one (all others died due to the great filter) must be the right one, and so, we are doomed. But the existence of the great filter was based on the assumption that were alone!!! The very moment we find an alien civilization, the assumption is no longer valid, and the reasoning makes no sense. The GREAT FILTER was supposed to be an EXPLANATION to understand WHY WE ARE ALONE. If we are alone, it’s because there must be some kind of great filter. But, IF WE ARE NOT ALONE, THERE'S NO REASON to believe that such a FILTER EXISTS!!! Am I missing something?

  66. William Dwinnell says:

    Or perhaps the great filter is so rare to overcome that it is not demonstrated in the observable universe, but still exists outside it.

  67. jože cvelbar says:

    Now this is a big brain channel

  68. shane taylor says:

    I’m stoned and very confused..

  69. _ xXPEGASUSXx _ says:

    maybe there is no great filter and this is just another 60Mo thrown into yt

  70. your local communist says:

    maybe it is good to be lonely?

  71. Pug Life says:

    Big brain

  72. StragglyPigeon6 says:

    That was kinda depressing

  73. Book Boy says:

    I think whats also important is light years. These planets are millions of light years away so if we look at them were seeing light relfect of of these planets from millions of years ago. It could be possible they have a super telescope and look at earth and see dinosaurs and are like "what the hell kind of hell planet is this?"

  74. jjsteer91 says:

    nah, load of nonsense this one.

  75. Climate Satyagraha : The Power of Truth says:

    Climate Change is most likely the great filter. Alteast for humankind it is.

  76. -_*THE MEMER*_- says:

    1:16 4:52 BIG BRAIN

  77. Eklypz312 says:

    Can't say the filter applies to every Galaxy if we can only begin to scan ours. Finding alien ruins is not a negative because we can observe what killed them and learn from it. Call me a absurdist/optimist but we could also meet a symbiotic relationship just like the mitochondria once did. As above so below.

  78. thegrandfinale2 says:

    Why alien life would be our doom? Because:
    "To Serve Man — IT'S A COOKBOOK!!"

  79. Brandon Naylor says:

    Blasphemous Xenos! may they be destroyed by the Emperor's light!

  80. Wetosi says:


  81. DoofusBoy says:

    1:17 Big Brain!

  82. Nicholas Major says:

    If we encounter plenty of life, especially intelligent, it means there's no great filter, or at least that it's behind all of those species. Can't agree with this video.

  83. Doge Bin says:


  84. Martín Andrés says:

    this video implies that life would develop the same way everywhere by Earth standards of life, there's no way of knowing for certain how life would develop in a non-Earth scenario unless we actually visit these places and gather samples, even then we don't have the equipment to carry these studies

  85. II Slothisey II says:

    Title: exists
    My childhood: you have insulted my culture.

  86. MegacoolZX says:

    I like to think that the Cold War is the great filter that ended most ET life and that one ship captain single-handedly made us the first civilization to survive the creation of civilization-ending weapons.

  87. EatYeezy RBLX says:


  88. Shawn says:

    Way too many assumptions in this video. "Why haven't we found aliens yet?" Well, how would you know when you've found them, for starters? Things that are that far away don't leave traces we can detect in what we would call "current time."

  89. Simon Fröch says:

    1:17 Pewdiepie would be proud

  90. Pixsa says:

    Where did you learn how to draw

  91. Clippy Lamusz says:

    Idk why but your voice, the video animation, and the sound effects cured my depression, thanks!

Leave a Reply

Your email address will not be published. Required fields are marked *