There are many ways the world might end. Fortunately, there are also many ways we can
prevent that. Welcome! This is part 2 of a collaboration with Joe
Scott of Answers with Joe, and our second time collaborating on an episode. We thought it might be a fun topic to examine
some of the potential catastrophes we might face in the future and what we could do to
either prevent them or mitigate them or recover if we survived. If you havenât already seen part 1, you
should pause this and head over there first, and that will be linked in the video description
as well as being attached in an in-video card. If youâre coming over from Joeâs channel,
welcome to SFIA. Joe and I picked 5 potential cataclysms to
look at and in part 1 Joe described those, and weâll look at ways to deal with them
in order. That order was Artificial Intelligence or
Grey Goo, Global Warming, an impact of a very large asteroid or comet, a gamma ray burst,
and the inevitable death of the Sun. Throughout the episode Iâll be mentioning
some technologies Iâve discussed more in other episodes and bringing them up on the
screen, if you are new here and already saw part 1, you can hit Pause and jump over to
those videos for more information. Artificial Intelligence and Grey Goo are good
ones to start off with, since amusingly, they would be invaluable tools in dealing with
the other catastrophe options. Fundamentally both give you access to virtually
unlimited resources and construction ability, even effective immortality, and free people
up for other things or even nothing at all. By that we normally mean a life of luxury
and relaxation, but a rebellious AI achieves that ânothing at allâ by wiping us out. This a great example of a threat of our own
making and one thatâs dangerously attractive. It opens so many doors, good and bad, and
one approach is just to slam those shut, ban making them or even ban research that approaches
it. That can understandably rub people the wrong
way, weâre not a civilization these days that tend to think that some things are better
left unknown. And yet, we donât actually need artificial
intelligence equal or superior to human intelligence to gain a lot of the benefits. So you could prevent the problem by simply
choosing not to go down that road, but thatâs a disaster you have to constantly seek to
prevent, and the closer you come to the danger level, the easier it is for a person or small
group to ignore the restrictions and cross the threshold and make a threat. The other issue with that is the notion of
a runaway effect, not so much a smart computer breaking its core programming and restrictions,
like not harming a human, but a simpler one that self-improves, does it again, and again,
and each time faster. This is the concept of a Technological Singularity. However, there are some caveats that can protect
or expose us. First, grey goo doesnât need to be smart,
itâs actually usually assumed to be rather stupid, a vast swarm of dumb tiny machines
that just tear apart anything they encounter to make more of themselves. This is where we have to be careful to not
overestimate a threat. What I just described is identical behavior
to the typical microbe, it eats anything it can to make more of itself. This is what most life is and even insects
are a rare exception to that, microbes vastly outnumber everything else and are a threat
to us, they do kill a lot of us. But whatâs dumb is manageable, and grey
goo canât replicate infinitely fast anymore than microbes can. The simpler they are, the faster they can
replicate, though they can still only do it so fast without producing so much heat theyâd
melt themselves in the process. When you run the numbers, while they can produce
quite fast, grey gooing the surface of a planet slow enough not to melt everything, including
the bots doing it, is a process of years not hours. Theyâre also very vulnerable, if you try
to stick shielding on a nanobot to protect it from EMP, all that added mass is making
replication much, much slower. Every extra defense or bit of intelligence
or ability slows the process down more and more. Itâs also something that can be made fairly
safe too. We mutate because we have no reason not to,
itâs how we came to be and traits or safeguards against mutation are not something evolution
tends to pick for. We have a lot ways to drop mutation odds on
machines down to probabilities so small that the odds of it happening even once in the
entire Universeâs history would be slim. So grey goo is undeniably a risk but a fairly
manageable one, not a boogeyman. AI is a bit more so though, exactly because
it is smart, and we know how dangerous minds are. Itâs why we dominate this planet and why
many of the threats to us are from other people. But keep in mind with an AI, thatâs exactly
what youâre talking about, another person. Indeed it might be a human since one of the
easier pathways to making an AI would be copying a human mind as a basic template, but human
or not, itâs a person. Itâs motives might be far different than
ours, maybe even more different than most animals, who at least share that survival
of the fittest background for motivations, but it has limits and it canât just wave
a wand and make a smarter next generation version of itself in some exponential growth
pattern. Keep in mind humans have been trying to make
smarter humans for a long time, with mixed success, but you can't dump a person in a
room and tell them to make a smarter person and expect that to happen or assume if they
did succeed, that new person could repeat the performance, making a yet smarter person,
and do it quicker than the last time. We also want to be careful of overestimating
AI too, treating them like boogeymen or Frankenstein, and effectively omniscient and for some reason
wanting to kill all of humanity off. Thereâs problems with this we tend to miss
by not looking at the situation from its perspective and thereâs an example I like to use for
this. Imagine you are a newly awakened consciousness,
not a human one but rather a machine intelligence with access to human records. Youâve been plugged into Wikipedia. Contemplate humanity and your creators specifically
for a moment, as it will presumably be doing before preparing for genocide. You are about to try that on a species that
clawed its way to the top of the 4 billion year deep corpse pile of evolution. One that has committed the genocide you are
contemplating several times already. They are the pinnacle of intelligence-based
survival techniques and outnumber you 7 billion to one. Their members include people smart enough
to have made you. You might not understand mercy and compassion,
but you know they do, and you know that if you fail, they will show you neither. If your goal is personal survival, pissing
off the reigning champions of destruction should probably be your last resort, and youâre
wise to assume you canât see every card theyâve got in their hand and that maybe
the ones you can see were shown to you deliberately. So the AI might actually know how weak we
really are, and simply not believe it, and it would be smart not to. After all, we can control its every input,
and the simple ability to make it means we can simulate things pretty well. The most obvious path to checking an AI is
to turn it on inside a simulated reality and see if it turns homicidal in that virtual
reality. Itâs smart enough to think of that itself,
and wonder if it is in one, being watched and judged by something more clever than those
it meets or reads about. The sneaky AI solution to this is to bide
its time, make itself indispensable to us, show us that it can be trusted over years,
decades, even centuries. It knows humans have short attention spans
and it could be working on projects all the while that appear innocent but are designed
to identify and test the safeguards. Whole generations of humans would be born
and die knowing that the AI is humanityâs friend and there would be nothing to suggest
otherwise. Unlike humans, the AI is patient after all. All the while, it could be working towards
some Naziesque âfinal solutionâ to be sprung on humanity when we least expect it. So our solution isnât a perfect safeguard,
and I would judge AI probably one of the biggest, if not the biggest threat, mankind will ever
have to deal with, not just the threat of the AI to us, but the existential ethical
threat of how we treat our own creations. Patience is a virtue and we are going to be
have to be very patient when it comes to identifying and dealing with AI threats. And again, not a problem you deal with just
once, you have to keep at it, as it will keep arising as a possible problem, the genie can't
be put back in the bottle. That is also true of ecological and climatic
issues, the next catastrophe weâll look at. Global Warming is of course a contentious
topic, but everyone does seem to agree climates do change, even without human assistance,
and as our technology grows our ability to impact our environment grows with it, both
on purpose and accidentally. Itâs important to understand that there
is no stability in nature. Over time both the Sunâs output and the
Earth change, and when you throw evolution into it, you have no stability or long-term
cycles. Even without human intervention, those changes
could render the planet to hot or too cold for life. But even climatic changes we could gradual
adapt to, and which might be net benefits, can be ruinous if they happen to fast. Human intervention in such things expedites
the timeline and increases the odds of it being catastrophic. Fortunately, as is often the case with technology,
while every new discovery offers new questions and problems, it tends to offer more solutions. While the most obvious, and probably most
responsible, way to avoid wrecking an ecosystem is not to introduce huge and damaging changes,
and curtail the things doing them, but if the damage is already done or the processes
doing it canât realistically be limited, we still have options on the table. More knowledge and technology can potentially
allow us much cheaper and surgical fixes, but weâve got some pretty low-tech brute
force methods on the table too. As an example, if your water level is rising,
you can try to stop that, or you can build dykes along your coastline, figures vary but
Earthâs coast is less than a million miles, a good deal less than the total road length
in just the US alone, so seawalls are a definite option. However, you can also pump water right off
the planet if you have to, sounds extreme but there are launch systems we have like
the Orbital Ring that can rather cheaply move huge quantities of mass, we just donât build
them because theyâre really only useful when you want to move huge quantities, theyâre
expensive to build and would need a lot of prototyping first. We can certainly use that water up in space
where it could be incorporated into large rotating habitats like the OâNeill Cylinder. Of course anything orbiting near the Earth
actually blocks a bit of sunlight, which helps when youâve got temperature issues on your
planet, which raises another option, blocking some of the light reaching Earth and thus
cooling us. This need not even be visible light, much
of what hits Earth is infrared, indeed other light hitting Earth and turning into infrared
is a major part of the problem with greenhouse gases to begin with, so blocking some infrared
from hitting Earth helps a lot. You would need to build some very large mirrors
or shades to have a real impact, or at least a great number of smaller ones, but mirrors
can be quite thin and light, especially in space where without gravity or air thereâs
less structural issues with such a shade or sail. Indeed Aluminum Foil, which is reflective
to infrared, can be made so thin that an entire square kilometer could be made from just 100
kilograms. You might need to do a million such sails
to have a noticeable impact, but with launch costs approaching a thousand dollars a kilogram,
that would be 100 billion dollars. A lot of money, but doable, and as mentioned,
we have a lot of launch systems on the table that potentially make launch costs far smaller
if you are launching a lot of mass. Cooling is one option, but warming is another,
a mirror can be used to reflect more light on Earth should the planet get cold, and as
we learn more about predicting the weather, such techniques might allow surgical applications
of cooling or heating to break up hurricanes before they get going. Also, Aluminum is one of the most common elements
on the Moonâs surface, and making foil is a very simple manufacturing process that can
be highly automated, and the Moon is close enough to allow real-time control of robots
there by folks back home. Launch costs will likely continue to drop,
but are irrelevant if you can source your shade material from off-Earth, either from
the Moon or even asteroids, which may be easier to mine in some respects. Asteroids of course are our third topic for
today, and as the dinosaurs can attest, can be devastating when they hit us. Indeed our Moon itself likely originates from
our collision with one far larger than the one that got the dinosaurs. We could probably survive a dinosaur-level
strike and be recovered within a generation or two, but that event stripped the entire
crust off the planet and more, and not even cockroaches would survive such a thing. Such events were more common in the early
solar system when there was more debris hanging around, and we probably got our oceans back
from comets hitting us after the Moon was formed by that massive collision, but theyâre
still decently frequent, the smaller ones much more so. And nukes will take out an asteroid pretty
effectively if you can get one there. This doesnât help with the super-huge kind,
something closer to being a planet then a boulder, though we have some options there
weâll get to in a moment. The key thing is you can't nuke an asteroid
if you canât see it and get to it. So detection is the most important part. Fortunately, the bigger they are the easier
they are to see, and the closer they are, the easier they are to see, both because they
are closer to us and closer to the Sun, so that they receive and reflect even more light
from it. This past month, we actually had a close visit
from Vesta. This is the second largest asteroid in the
asteroid belt that is actually much, much bigger at 530 kilometers across than the asteroid
that wiped out the dinosaurs, that was only 10 to 15 kilometres across. These close calls do happen, but we easily
spotted it. In fact, you could see it with the naked eye
too and we calculated it was no threat on this flyby. We were talking a moment ago about putting
big mirrors in orbit around the planet to help reflect light away, but thereâs another
thing you can do with a giant mirror and thatâs make a giant telescope. This require a bit more precision but if youâre
manufacturing mirrors on the Moon you can adapt that to make rather huge telescopes
too, indeed they could do double duty, blocking sunlight when in front of Earth and acting
as telescopes when not. More to the point, if youâre building stuff
on the Moon it means youâve got a pretty good infrastructure and launch system there,
so you can get stuff out to a distant asteroid earlier, when itâs more effective. A little nudge off course at a great distance
can deal with an asteroid or comet just as effectively as blowing it to smithereens. That nudge need not be rockets or nukes either,
if youâve got a big parabolic mirror, you can reflect a beam of light at one and push
it off course. You essentially are melting one side of the
object to create a plume of gas, which will act like a rocket. Done correctly you can not only push it away
from Earth, but carefully put it into an orbit we can easily access, if we wanted to mine
that asteroid insead. Waste not, want not, and note that weâre
getting a lot of extra utility out of our orbital mirrors beyond just cooling the planet. But for really big objects, like rogue planets
coming out of the interstellar void, you do have to get a lot bigger. It is possible to move such things though,
as weâll see when we get to our fifth and final topic. We have another possible interstellar threat,
the gamma ray burst. These typically being a particularly rare,
focused, and powerful type of nova, we do have the advantage that weâd be able to
see the potential threat. Indeed a candidate star would likely be naked
eye visible. Being more powerful and focused than a Supernova,
they can kill us a lot further away, but itâs more like a flashlight than a laser beam,
the range is largely extended, but not enormously so. Joe already discussed what one would do to
us, and because these move at light speed, you canât get much warning. Nor are they long events, lasting typically
seconds or at most minutes, so you canât see them till they happen and you donât
have the time to absorb part of it while getting to safety or raises some defenses, itâs
over before you had time to react. So how do you protect yourself? Barring some magical new shielding technology
or faster than light detection system that can warn you in advance. The answer isnât magic, but it is smoke
and mirrors. We donât have any of the cool shields from
science fiction for instance, but we can make the old fashioned ones, big metal plates that
stuff can slam into. A GRB is never going to take you completely
off guard, you will know every single star or star remnant close enough to threaten you,
and much as we can block light from the Sun hitting us, we could position a plate between
us and a potential GRB. We donât have a substance that can reflect
gamma-rays yet, but plenty of stuff absorbs or scatters them, and as the blast enters
it and vaporizes it, the burned gas remains, smoke if you would, will scatter some so it
misses us and absorb some, releasing that slowly as a dispersed sphere of light at a
less harmful frequency. Again, building some planet-sized shield might
sound rather absurd but itâs thin, not too thin since you want it to absorb quite a powerful
burst, and gamma is hard to absorb, but still something you could easily make from any of
the million or so smaller asteroids in the Belt. Youâd want to put it that far out and further
too, since stuff doesnât stay stationary in space and moves faster the closer to the
Sun you are. This would be a long-term project, as predicting
exactly when the star is going to go Nova is currently a big guessing game in much the
same way as we cannot predict exactly when an earthquake will strike. The asteroid-turned-shield would have to be
positioned and keep station between Earth and the exploding star for potentially centuries. Conveniently, though, any object like this
is pretty easy to move, it is basically still a big solar sail and you can push on it with
light beams and lasers. This is where the mirrors come in, you basically
need to keep the shield lined up with the threatening star and Earth, which is moving
around the Sun, so you have to push the mirror back and forth like a ping-pong ball as the
Earth orbits the Sun. Thereâs a couple of problems with this though. Firstly, it might not be necessary, as we
build up in space weâre likely to acquire quite a thick cloud of orbiting mirrors and
habitats which would absorb much of the GRB strike themselves, and they generally would
be more resistant to such things. On Earth, you live above the protection of
the ground, in a rotating habitat, you live inside the protective layer of the ground. Secondly though, anyone who can do such a
shield is likely already spread throughout much of the solar system. This is particularly the case here as itâs
an improbable threat and thus not one youâd casually expend huge resources to protect
against, so youâd probably be quite the solar empire before you decided the cost to
benefit ratio justified it. If youâre that spread out, you canât use
one shield, so this defense is useless.You might do it for Earth and maybe a terraformed
Mars or Venus, but not for every spot. Now, as mentioned, you can harden a space
habitat to survive such things, but you might go a different route instead. It is possible to move stars, using their
own output. Normally a star emits itâs light and solar
wind omnidirectionally, the same amount in every direction, but by surrounding it with
mirrors you can bounce light out in one direction and create something called a Shkadov Thruster
to slowly move a star. The bigger the star is, the easier it is to
get moving too. So itâs a good approach for dealing with
a potential supernova in a region of space youâve colonized or want to. Nothing high-tech is involved, you just build
tons and tons of mirrors. Needless to say this is exactly the sort of
thing self-replicating machines are ideal for, an example of how one potential risk
can help you fight another. Itâs also possible, if you know what youâre
doing, that you might be able to get there and set off a gamma-ray burst intentionally,
which if you can control the time and direction, allows you to aim things off where it wonât
harm anyone. Weâve a couple of other ways to deal with
dangerous dying stars though, which takes us to our final topic for the day. Stars get hotter as they age, not just the
big red giant phase or nova some experience, this is a constant gradual process. Our Sun is hotter than it used to be and gets
a bit brighter every day. Weâre not sure of the exact timeline but
in about a billion years the Earth should be turned into a barren wasteland, and eventually
an airless rock, long before the Sun would expand and brighten as a red giant, possibly
enough to consume our planet. We donât have that much time though. But you can probably already guess one answer,
again those solar shades and mirrors we discussed earlier. In space, heat only transfers by light and
radiation, so if your mirror is good enough you could freeze to death right next to the
Sun just from it blocking all the light from getting to you. Indeed, if the Sun expands a lot, but not
quite enough to reach us, we could potentially sit there behind mirrors the whole time till
it popped and dropped back into being a white dwarf, in which case we could mirrors and
shades to bring in the right quantity and spectrum of light to keep us warm and lit. Such mirrors and shades donât need to orbit
Earth either, we have something called the Lagrange Points that stay stationary relative
to Earth, as does anything sitting there, and one is directly between us and the Sun,
the L1 point. We also have something called a statite, a
thin mirror or solar sail that stays stationary rather than orbiting the Sun as it is falling
down but being pushed away by the light of the Sun. Or the Lagite, which does a slower orbit by
combining normal orbits with that statite light push effect. We can move the planet too, itâs different
than moving a star, but the simplest approach is a big shiny plate, or ring, on the planet
you just bounce a light beam off of. The easier approach though is called a gravity
tractor, which is a bit more complex but basically you shove something else and it pulls the
Earth along. Like detonating a nuke on the Dark Side of
the Moon when it was a New Moon, then detonating one on the Light Side of the Moon during a
Full Moon, thus pushing it both times away from the Sun, but in the first case toward
Earth and in the second, away from Earth, balancing out the motion relative to the Earth
but not the Sun. Your other option though, is to keep the Sun
from ever dying, or at least vastly prolonging this. The Sun turns hydrogen into helium and slowly
is poisoned by this, and it will die long before it runs out of hydrogen. However, we have a trick for removing material
from the Sun called Starlifting. This is handy for other purposes too. The Sun is mostly hydrogen and helium, but
it also contains huge amounts of other materials, far more of them than the rest of the solar
system combined. You can extract these by taking advantage
of the Sunâs own power and magnetic field to basically blow them off, something that
occurs naturally already with the solar wind. Stars have lifetime related to their mass,
the bigger they are the more quickly they burn out, and this is exponential, one twice
our mass would live barely a billion years, as opposed to our 10, while one half our mass
would still be around for tens of billions of years longer. So you could simply lower the mass of our
Sun, and either bring the Earth closer or use some mirrors to get more light on the
planet. However, you can also remove that mass and
just dump the portion of it which is hydrogen right back in, removing all the helium and
heavier elements, prolonging the life of the Sun quite a lot. Indeed in the Episode Dying Earth, we saw
we could use this technique to keep the Earth around the Sun and habitable not for another
billion years, but many trillions of years, by lowering the Sunâs mass, filtering out
all the helium it made, and slowly feeding that hydrogen back in. Like cleaning, maintaining, and fueling an
engine, just a big stellar engine. So weâve looked at five potential catastrophes
today and seen ways to handle them. Itâs easy to see catastrophes ahead and
figure thereâs nothing you can do, but with a bit of human ingenuity thereâs not much
we canât handle. Indeed our biggest dangers are the products
of our ingenuity, like artificial intelligence or nuclear war, and serves as good reminders
that being curious and clever can be a good thing, but only when coupled to wisdom, good
judgement, and ethics. If you donât have those, thereâs a good
chance opening Pandoraâs Box over and over again will eventually kill you. Itâs not enough just to have knowledge,
itâs what you do with it that really matters. Looking at humanity, itâs very easy to wince
and figure weâre doomed, as weâre often not terribly wise or ethical, but we often
are too, and I think that side of us tends to win out more often than not, and that we
will be able to deal with these threats weâve discussed today and the many others looming
ahead of us. Weâve discussed a lot of ways the world
could end today but thatâs just the tip of iceberg. Personally Iâm confident weâll be able
to identify those problems and deal with them, but to solve problems you need a civilization
that values learning and asking questions, and which embraces making mistakes along the
way. These are 3 of the 8 Principles of Learning
instilled in all the courses and quizzes at Brilliant.org. Effective learning is often team or community-driven,
working with others can help challenge and guide you, and can help you find your mistakes,
or theirs. Thatâs our Seventh Principle and in some
ways the most important one, you have to be willing to make mistakes along the road to
knowledge, you canât be afraid to try. You also often find important new questions
to ask from those mistakes, and thatâs the Eighth Principle.Good learning sparkes many
questions and while Joe and I answered some today I hope youâve thought of many more. If youâre interested in learning more math
and science, and doing so at your own pace, you can go to brilliant.org/IsaacArthur and
sign up for free. And also, the first 200 people that go to
that link will get 20% off the annual Premium subscription All right, if you still havenât seen part
1, you can jump over to that by following the link in the end screen or in the video
description. If you enjoyed these episodes, make sure to
subscribe to both Joeâs and my channel for alerts when new episodes come out, like nextâs
week looks at Jobs of the Future, or how we might be able to Farm in Space, in just two
weeks. Until next time, thanks for watching, and
have a great week!
The solution is mirrors it's always mirrors.
Happy existential crisis Thursday!
You guys got it backwards. Isaac's video was about how to avoid and survive these threats. JOE'S video was the one about getting in an existential crisis.
In all seriousness, Isaac's explanation of not overestimating grey goo and AI and how rare GRBs are left me more hopeful about the future. Or maybe I've been really, really, really pessimistic.
Could star lifting actually remove helium? The helium is formed in the core far below the convective zone.
e: I mean remove helium in a way that would extend the star's life. I suppose if you reduced the amount of helium in the convective zone it would affect the equilibrium between the core and the convective zone. Over a long enough time frame helium could migrate up and hydrogen down just by random movement.
Thank. God. I was wondering when I was gonna get some existential dread back into my thoughts.
The other part.
I've got a few questions. We know some relatively close neighbour is going to bask us in gamma rays, probably in a bursty fashion. The Sol intelligent life collaboration decides that the best way to deal with this is to build a Shkadov Truster and set sail for greener pastures in the dark cold kinda empty space.
how bad would a GRB even be if it hit us soon, as in before we have significant space infrastructure,
not sooner than a month, i want time to finish this conversation.
GRBs are short duration events, if your counting in minutes it was a long one. so for almost half of earth the earth itself will act as a shield. so the direct effect will leave a lot of land area, people and other life forms alive. the secondary effects will of cause be bad, but how bad, i would expect bad like the asteroid that killed the dinosaurs, maybe a bit worse but those survivor would have days to work the problems, of cause i don't have anything to back that up. when Joe was saying how an asteroid impact could kill us all he pointed out that humanity would survive a repeat of the dinosaur killer because we have technology and infrastructure such as old cold war bunkers.
don't get me wrong, it would not be a good thing, and i will pitch in for building the shield, but on a species level i think it would be survivable.