The Universe is incredibly big and seems full
of potential for life, with billions of habitable planets. If an advanced civilization had the technology
to travel between the stars, at just 0.1% of the speed of light, It could colonize our
galaxy in roughly 100 million years. Which is not that long given the billions
of years the milky way has existed – so in principle any spacefaring civilization
should be able to spread rapidly over huge sectors of the galaxy. And yet we see nothing, hear nothing, the
universe seems empty. Devoid of others. This is the Fermi Paradox, which we have discussed
in more detail in other videos. Confronted with the seemingly empty universe,
humanity faces a dilemma. We desperately want to know if we are alone
in the Milky Way. We want to call out and reveal ourselves to
anyone watching but that could be the last thing we ever do. Because maybe the universe is not empty. Maybe it’s full of civilizations but they
are hiding from each other. Maybe the civilizations that attracted attention
in the past were wiped away by invisible arrows. This is the Dark Forest solution to the Fermi
paradox. The Way Of Life The hunter awakes in his hiding place and
carefully listens for suspicious noises from the thick undergrowth before he gets up. Another night has passed without incident. The forest is dark and full of fog. He considers calling out to others to end
his loneliness but stops himself at the last moment. What if they are like him? All living things seek to survive, secure
resources and multiply. Their greatest obstacle are other living things
that share the same objective. Competition between species favored the survival
of beings with advantageous traits. Our ancestors were inventive, competitive,
expansionist and greedy for resources, which led to them winning the competition for our
planet. Today, most other animals are so utterly at
our mercy that we wipe out about a dozen species a day, just as an unintentional byproduct
of how we like to run things. But humans are more than individuals. From us cultures emerge, that also compete
with each other. Competitive and expansionary cultures spread
faster and further and merge with, subdue or destroy others. If we look at our history it becomes clear:
We are dangerous. Not just to others but also to ourselves. Our human nature has driven us to take over
every corner of our planet and soon we will look to the stars, both to expand our domain
and ensure access to ever more resources. And then we might stumble upon others trying
to do the same thing. It is likely that the competition of life
also takes place on far away planets, so it is logical to assume that an alien civilization
that came to dominate their planet would be in some regards similar to us. But if they are similar to us, they, too,
may be dangerous. The Implication As the hunter sneaks through the dark forest
all alone he knows that there might be others like him. He can’t know their intentions, if they
are aggressive or not. The hunter knows he would kill to ensure his
own survival, so he has to assume that they would too. And it might be that if he stumbles upon another
hunter, the one that shoots first survives. None of this means that conflict is unavoidable. So far the progress of the modern world seems
to have made us more peaceful, not more violent. Maybe this is true for other civilizations
too, that eventually progress means less conflict, not more. Different alien civilizations also should
vary from the mild and peaceful to the malevolent and militaristic. The existential problem we are facing is that
when we meet others between the stars, we have no way of telling who is peaceful or
aggressive and what their true intentions are. Similarly, they might not understand or trust
our intentions even if we tell them that we are peaceful. On top of that, if we did discover another
civilization, and they discovered us, the light years between us would mean years of
communication delay. Both sides would be in a state of uncertainty,
wondering if the wisest move is to just attack, because there's another serious issue: technological
explosions and first strike advantage. We do not know where the limits of technology
are, but we do know how much technological progress matters in war. A few hundred or thousand years can turn conflict
with uncertain results into a one sided massacre. Caesar's legions would stand no chance against
Napoleon's army with their cannons and muskets. Which would be eradicated by artillery from
the first world war. Which would not stand a chance against today's
drones and guided missiles. So the power level of different civilizations
may vary massively and even if not, between the time it takes us to detect another civilization
and us saying “hi” we might already be hopelessly behind on the tech tree. Which is bad enough, but the nature of interstellar
conflict makes this worse. If your opponent is light years away, sending
an invasion fleet takes so long that by the time it arrives it might be hopelessly obsolete. So, war between civilizations might be just
about eliminating the other to remove an existential threat to yourself. Someone else who might be so scared of you
that they attack the first chance they get. In this environment, the only way to guarantee
a win is to strike with such force and speed that the target has no chance of survival
or time to counter-attack or escape to seek revenge later. The stakes are the highest possible with no
room for error. If we assume that the majority of civilizations
live on planets that leaves them pretty vulnerable – all you need to do is throw something
massive at a planet to make it uninhabitable. So the ultimate interplanetary annihilation
weapon is probably something like a Relativistic Kill Vehicle – a missile shot at a planet
at a significant fraction of the speed of light. For example, a missile the size of a person
going 95% the speed of light has as much energy as all nuclear bombs on earth. If you shot a few dozen at the civilization
you wanted to wipe out, success would be fairly certain – even a single hit would suffice. This is not that absurd of an idea – a civilization
only slightly above us on the Kardashev scale would have enough energy to send multiple
strikes against every planet it suspects of harboring life. What makes these weapons so sinister is how
much they favor a first strike, since they would be so fast that it might be impossible
to protect yourself effectively against them once they’re launched. Conflict between civilizations may not be
lengthy affairs but rapid winner takes all situations, where the first one to shoot wins. This makes any civilization an existential
threat to any other. And if every civilization is an existential
threat to every other, there may be only two kinds of civilizations out there: quiet ones
and dead ones. So what should we do? So, should we worry? It is unlikely that anybody has noticed humanity
yet. The radio signals we’ve transmitted in the
last 100 years traveled a relatively tiny distance and have long decayed into unreadable
noise. At our technological stage, if we don’t
actively try to get noticed and if nobody specifically looks at our pretty unremarkable
solar system, we’ll stay hidden. But one day we will venture into space in
a serious way and need to consider these kinds of questions again. We don’t know if there are others or if
we are going through the forest alone. But we have no way of knowing for sure. For the time being, it seems the best we can
do is to carefully listen. And even if we see others step into a clearing
and make themselves known, we should not reply right away but carefully watch them from the
undergrowth. Perhaps we are also thinking about this all
wrong by allowing our primitive brain, that evolved in the context of the gruesome competition
of life, to conjure fears of predatory aliens all around us. Maybe the fact that we are looking at the
universe like this is a sign that we are not grown up yet as a species. There could be a friendly, welcoming community
of alien civilizations waiting to hear from us when we are ready. As for now, the good news is there is actually
little we need to do. We just need to be thoughtful about the signals
we send out into the galaxy, we need to watch the sky and learn more about our galaxy, our
forest. Because whatever the nature of our forest
is, full of dangers or friends, or nobody at all, only careful observation can tell. So let’s do that. At last the hunter reaches a clearing and
finds a comfortable position. Slowly the sun melts the fog away, lost in
thought he admires the vegetation until suddenly – he is eye to eye with another hunter,
frozen in terror just like himself. His mind is racing, considering all the different
options. The hunter takes a deep breath and makes a
decision. Maybe the only way out of the dark forest
is to step into the clearing together. And with this hopeful picture, we say goodbye
to the year 12021 of the Human Era. It was a wild year to say the least, still
much more fun than 12020. Kurzgesagt had its most successful month ever
and published a book. We tried a lot of new techniques and really
got into blender and Cinema4D, hiding more and more 3D in our videos. We have so many ideas for next year and big
and ambitious plans that we can’t wait to share with you – and all of this was and
is possible because of your direct support – thank you so much. Kurzgesagt only works because of you. So in tune with the end of the year we designed
a few products that will help you to visualize your place in the universe. Our very shiny “The Night Sky'' Poster shows
you the little piece of space we can see from Earth with our own eyes, or travel further
out with our Stellar Zoom Collection that depicts our home in space from an increasing
distance. Or dream with our Space themed notebooks,
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Description
The Universe is incredibly big and seems full of potential for life, with billions of habitable planets. If an advanced civilization had the technology to travel between the stars, at just 0.1% of the speed of light, It could colonize our galaxy in roughly 100 million years. Which is not that long given the billions of years the milky way has existed – so in principle any spacefaring civilization should be able to spread rapidly over huge sectors of the galaxy. And yet we see nothing, hear nothing, the universe seems empty. Devoid of others. This is the Fermi Paradox, which we have discussed in more detail in other videos.
Confronted with the seemingly empty universe, humanity faces a dilemma. We desperately want to know if we are alone in the Milky Way. We want to call out and reveal ourselves to anyone watching but that could be the last thing we ever do. Because maybe the universe is not empty. Maybe it’s full of civilizations but they are hiding from each other. Maybe the civilizations that attracted attention in the past were wiped away by invisible arrows. This is the Dark Forest solution to the Fermi paradox.
Sources & further reading:
https://sites.google.com/view/sources-darkforest/
If you're interested in this topic and reading sci-fi, I highly recommend a series by Liu Cixin. One of the best modern sci-fi novels in my list.
Is it just me or has their video production really been crazy this year?
I really LOVED how this video is like a beautifully explained summary of the background ideas explored in the Three Body Problem series by Liu Cixin
Wasn't ready for the real human bean Easter egg
Sounds a lot like the prisoners dilemma to me.
We do not know the intention of others, but mathematically speaking working together with other civilizations despite our and their distrust is the best way for both civilizations to reach their goals.
All we have to do is to build many self sustained colonies around the solar system before reaching out. They can't wipe out the entire solar system, can they?
RKVs always get brought up for this, ever since The Killing Star, but they are just as plausible as the dual-vector foil.
Imagine firing something at 9/10ths the speed of light at a target ninety light-years away. In order to strike a planet, the window of time your RKV has to hit its target is at most 1/5th of a second, possibly less, after a hundred-year journey. And to hit the correct -position-, not just time, the mass of Neptunian and Uranian moons are relevant, as are Kuiper belt objects. The slightest errors in measuring Earth's position - if you ever managed to get it in the first place - can render such an attack worse than useless.
A few dozen RKVs isn't enough - you need trillions. It's moot however, because in order to accelerate something past a few percent of c, you either need to use light sails - good luck hiding that from your target - or multiple light years of coil in order to avoid vaporizing your projectile.
I've actually done a ridiculous amount of math for this if people are interested.
I would, perhaps naively, more like to assume that not every alien empire would obliterate us with extreme prejudice at the first opportunity they got. Maybe our fear that they would do so only reflects our own immaturity as a species. Then again, which side of that is more naive I guess mostly comes down to the attitudes of whoever else is out there.