Let's take over the universe
in three easy steps. Welcome. We've heard that you want
to take over the universe. Well, you've come to the right place. In this video, we'll show you how
to reach as many as 4 billion galaxies,
with just a few relatively easy steps and 6 hours of the sun's energy. Here's what you need to do. One: Disassemble Mercury
and build a Dyson swarm, a multitude of solar captores
around the sun. Two: Build self-replicating probes. And three: Launch
the self-replicating probes to every reachable galaxy. In science fiction humanity's
expansion into the universe usually starts within our galaxy,
the Milky Way. After a new star system is occupied,
humanity jumps to the next star and so on. Until we take the whole galaxy. Then humanity jumps
to the next nearest galaxy and the process is repeated. This is not how we're going to do it. Our method is much more efficient. We're going to send
self-replicating probes to all the
reachable galaxies at once. Getting to the furthest galaxies
is not more difficult than getting to the nearest ones. It just takes more time. When a probe arrives
at its destination galaxy, it will search
for a planet to disassemble, build another Dyson swarm
and launch a new wave of probes to reach every star
within the galaxy. And then each probe in that galaxy
will restart civilization. We already hear your protest,
though: 'This whole thing seems pretty hard to me,' you say. 'Especially the "disassembling
mercury" part.' But actually, none of these steps
are as hard as they first appear. If you analyze closely
how they could be implemented, you'll find solutions
that are much easier than you'd expect. And that's exactly
what Stuart Armstrong and Anders Sandberg
do in their paper, 'Eternity in six hours: intergalactic spreading
of intelligent life and sharpening the Fermi paradox.' This video is based on that paper. Exploratory engineering
and assumptions. What we mean by 'easy' here is
that we will require amounts of energy and resources
that are small compared to what is
at our disposal in the solar system. Also, the technology required
is not extremely far beyond our capabilities today,
and the time required for the whole feat
is insignificant on cosmic scales. Not every potential future technology
will make sense to include in our plan
to spread to the stars. We need to choose what technologies
to use by reasoning in the style
of exploratory engineering, trying to figure out
what techniques and designs are physically possible
and plausibly achievable by human scientists. The requirement 'physically possible'
is much easier to comply with than 'achievable
by human scientists', therefore, we introduce
two assumptions that serve to separate the plausible
from the merely possible: First: any process
in the natural world can be replicated
with human technology. This assumption makes sense in light
of the fact that humans
have generally been successful at copying or co-opting nature. And second: Any task
that can be performed can be automated. The rationale for this assumption
is that humans have proven to be adept
at automating processes and with advances in AI,
we will become even more so. Design of the Dyson Swarm. Now we've said we're going
to launch probes to every reachable galaxy. This means a hundred million
to a hundred billion probes. Where do we get the energy
to power all these launches? We don't need to come up
with exotic sources of energy we can't picture yet. We can use the sun itself! That's why
we're going to build a Dyson swarm. To be fair, in order to be sure
that a Dyson swarm will be sufficient,
we need to already have plausible designs for probes
and launch systems in mind. But this is a tutorial for pragmatic,
wannabe grabby civilizations. So we'll get to that later,
when we actually use them. A Dyson swarm is simply a multitude
of solar captors orbiting around the sun. The easiest design
is to use lightweight mirrors, beaming the sun's radiation
to focal points where it's converted
into useful work - for example,
using heat engines and solar cells. A Dyson swarm has major advantages
compared to a rigid Dyson sphere. A swarm isn't subject
to internal forces that might make it collapse,
and it can be made with simple
and conventional materials. Even a swarm isn't
without potential problems, though. The captors have to be coordinated
to avoid collisions and occluding each other. But these are not major difficulties. There are already reasonable orbit
designs in today's literature and the captors
will have large amounts of reserves at their disposal
to power any minor course correction. The efficiency of the captors
will not be an issue either. We'll need only a small amount
of energy to power our expansion into the universe
compared to the energy a Dyson swarm
will be able to collect. The biggest problem to solve
is how to get all of the material necessary to build the solar captors,
even assuming the lightest design achievable with today's materials. That is lightweight mirrors. You'd need to take apart Mercury
to get everything you need for the swarm. And that's exactly
what we're going to do. There are potentially other pathways
to get the material, but being able to take apart Mercury
is the conservative assumption to make, as weird as it sounds. We're not assuming
future super materials that would let us build a swarm
with extremely thin and efficient captures
and therefore with way less material. Mercury looks very convenient
to use in comparison to the other planets
and the asteroid belt. Its orbit is approximately
at the same distance from the sun as the swarms,
and it's a rocky planet. 70% metallic and 30% silicate. This is material
that we can transform into reflective surfaces
for the swarm and use to build heat engines
and solar cells. The Semi-major axis
of Mercury's orbit is approximately
60 billion meters long. Therefore, a sphere around the Sun
with that radius would have a surface area
in the order of ten^22 square meters. The mass of Mercury
is in the order of 10^23 kilograms. Now, let's assume
we'll use about half of Mercury to build the swarm. If we conservatively pretend
that the swarm is a solid sphere around the Sun,
we can take the fraction between half of Mercury's mass
and the surface of the sphere we just calculated
to get the mass of the sphere per square metre,
which is 3.92 kg/m^2. This is plenty! Iron has a density of 7874 kg/m^3,
so we can obtain mirrors with a thickness
of at least half a millimetre. We can already easily
make mirrors this thin. You can order them
online if you want, but most probably
we would use a structure with a much thinner film
of the order of 0.001 mm, supported by a network
of rigid struts. Disassembling Mercury. Now let's disassemble Mercury
and build this swarm, shall we? We're going to build the Dyson swarm
during the process of disassembly. While we get material
from the planet, we build more of a swarm,
and as we build new captors, we get more energy to power more
of the planet's disassembly, and so on. Essentially, we need a feedback loop
like this: We mined necessary material,
we get the material into orbit, we make solar collectors out of it,
we get the energy from the collectors,
and we use that energy to mine more material,
and so the cycle repeats. Sandberg and Armstrong
assume a seed of 1 km^2 of solar panels
constructed on Mercury to start the feedback loop. After the seed, the loop can begin
with mining the initial material. At each cycle,
we have more energy at our disposal to power more mining, and the process
can easily speed up exponentially. In fact, the feasibility
of Mercury's disassembly hinges on if we get
an exponential feedback loop or not. If we can't complete the loop
or if it's not at least near exponential,
then we're out of luck. The process would grind to a halt
or be impossible to complete in any reasonable amount of time. If we want the energy at our disposal
to increase exponentially, the number of captors must increase
by a fixed percentage at each cycle. That means that the energy
required to mine minerals, get them into orbit and make captors
must remain nearly constant or decrease at each cycle. But this is not a big concern. Mining material and making
solar collectors shouldn't consume more energy
as the disassembly progresses. On the contrary,
towards the end of the disassembly, less energy will be required
to get material into orbit, as Mercury's gravity
will be much easier to overcome. A potential problem
could be cooling Mercury's core, but this is a fixed cost,
and Mercury's heat might be harvested
to get more energy. And now maybe you're thinking: 'Wait,
even if we can get an exponential
feedback loop in theory, how on Earth are we going to get
the workers to do all this?' And that's where our assumption
that 'any task that can be performed can be automated' comes in. With automation,
the sheer scale of projects is simply not a problem. New machines and factories
can be built essentially without human intervention. Time, material and energy
become the only things we need. Encouragingly, NASA had a design
for a self-replicating lunar factory in 1980. And surely, in the future
we'll be able to do much better than NASA in the 80's. Sandberg and Armstrong
make a few additional assumptions to precisely estimate
how long it'll take to complete the Dyson swarm. They assume: Solar captors
with an efficiency of 1/3. Only 1/10 of the energy will be used
to propel material into space. The rest will be used for mining
or reprocessing material, or simply be lost. It takes five years
to process the material into solar captors and place them
into the correct orbit. And only half of Mercury's material
will be used to construct the captors. Under these assumptions,
the power available will increase exponentially
every five year cycle. Mercury will be disassembled
in 31 years with most of the mass harvested in the last four years. But as long
as the exponential feedback loop is possible, the details
aren't that important and will complete the disassembly
within a few cycles and a short amount of time. And even if an exponential
feedback loop turns out not to be possible,
it doesn't necessarily mean we can't build a Dyson swarm. This is just one way
to attack the problem, which relies
on plausible future technology constrained by
conservative assumptions. For example, if we're able to produce
super materials, taking apart a large asteroid
might be sufficient. Design of the probes. Now that we've built the Dyson swarm,
we have the energy to launch countless
self-replicating probes into the universe. Our probes should be capable
of safely landing on other planets or asteroids,
using the resources there to make copies of themselves. Building other Dyson swarms,
launching another wave of probes, and ultimately starting civilization
on other star systems. By guessing that building
self-replicating probes will be possible
with future technology, we're essentially making use
of the assumption 'Anything possible
in the natural world can also be done
under human control'. Every living thing
is capable of replicating. Here's a table of some
of the smallest replicators in nature. The smallest seed on earth
weighs a billionth of a gram, and the smallest acorn weighs 1 gram. Think about it. An acorn is a solar powered factory
for the production of more acorns that generates large structures
in the process: Namely oak trees. When thinking
about the size of our probes, we need to make a distinction
between the self-copying piece of the system, and the whole object
that gets launched, which may include fuel,
rockets for deceleration, and other equipment. A reasonable upper limit
for the size of the replicators is 500 tons. This is the size of the replicator
in NASA's self-replicating lunar factory design, which made
very conservative assumptions. As a lower limit,
we can use the design of Molecular Assembler
by Robert Freitas and Ralph Merkle, from their landmark
book 'Kinematic Self-Replicating Machines', a comprehensive review
of self-replicating designs up until 2004. The mass of this replicator
would be in the order of 10^ -18kg. For reference,
this is about a million times smaller than a red blood cell. The data storage on the probe
would probably be of insignificant mass. An extremely compact design
would be a diamond constructed with carbon
12 and carbon 13. The two isotopes
would encode the bits 0 and 1. A memory like this
would have a capacity of 6 billion terabytes per gram. Or we could use
a data storage mechanism with the same compactness as DNA,
in the order of 100 million terabytes per gram. As a comparison,
the total amount of data in the human world in 2020
could be stored in about 500 grams
of DNA-level storage. Apart from the replicator,
the probe needs fuel to decelerate when approaching its destination. Sandberg and Armstrong hypothesized
three possible types of fuel to power the deceleration. In order of increasing
speculativeness and efficiency, they are: Nuclear fission,
nuclear fusion, and matter-antimatter annihilation. As you can see in this table,
they calculated the mass of fuel needed, given
different deceleration amounts and type of fuel. In the table the replicator
is assumed to weigh 30 grams. You can take the 'delta v' column
as also indicating 'starting velocities' if the probe
then decelerates to zero. The values in bold
are the kilograms of fuel needed, given the most reasonable
combinations of starting velocities and type of fuel available. This table doesn't take into account
many things that could aid deceleration, though. For example,
the trajectory of the probe might be designed
to use gravitational assists to slow down, or magnetic sails
could be used to create drag against the local magnetic field
in the destination galaxy. Moreover, the expansion
of the universe means that
some amount of deceleration will come for free,
and probes launch to distant galaxies would arrive with little velocity. In that case, we would need fuel only
for maneuvering at the end. There are many
other speculative options to help decelerating,
such as the Bussard ramjet, which uses enormous magnetic fields
to collect hydrogen atoms from the interstellar medium
and compress them to achieve nuclear fusion. Another potential design choice
for the probes is to equip them with shields. Intergalactic space is not empty. The probes might encounter dust,
and at relativistic speeds, collisions can easily
destroy our probes. Another solution is simply
to launch redundant probes to compensate for the fact
that some might be destroyed. Sandberg and Armstrong estimate
that for speeds of 50% to 80% the speed of light
launching two probes per galaxy is enough to expect
that at least one will arrive. If the probes travel at 99%
of the speed of light, then we'd need to launch
40 probes to each galaxy. The launch phase. All right, now let's say we've chosen
a viable design for the probes. Their construction
has taken little material compared to the Dyson swarm. The final combined mass
of all the probes, redundancy included,
is in the order of 10^11 to 10^12 kg. This is about the mass of a mountain. The Dyson swarm is operational
and provides us with all the energy we need. It is time to launch the probes. We'll not use rockets,
but a fixed launch system. Rockets would be needlessly difficult
and inefficient to use for achieving acceleration
to relativistic speeds. They need to carry fuel,
which would in turn need to be accelerated
and the fuel needed increases exponentially with the change
of speed we want to achieve. Fixed launch systems sidestep this
and are often reusable. For example, we could use coilguns. Essentially long barrels
around which coils are arranged and switched
on and off with precise timings, closing the probe in the barrel
to accelerate due to the magnetic forces
generated by the coils. With coilguns
we could shoot our probes into space in combination
or by themselves. We can also use solar sails
accelerated by lasers or particle beams. Now look at this table. For each type of probe
and for each type of replicator you can find in bold the time
required to power the launch if the energy of the Dyson swarm
were entirely devoted to the task. In the case
of the 30 gram replicator, the numbers are insignificant
on a human scale. 6 hours of the sun's energy
is the maximum we would need. Instead, if the replicator
is the 500 tons version, we would need hundreds of years
of the sun's energy. But this also looks very feasible
if you consider that humanity
might survive millions of years and over time
might divert some energy of the Dyson swarm to power launches
and not necessarily launch all the probes at once. After the universe, the galaxy. Now picture a future President
of the Solar System proclaiming: 'Everyone turn off
your virtual reality sets for 6 hours. We're taking over the universe!' The probes are launched
to every reachable galaxy, and the travel begins. Once this first wave is en route,
we can launch a new wave of probes within the Milky Way at lower speeds. So we'd start expanding
into our own galaxy only after having started
expanding into the wider universe. Meanwhile, the probes we've launched
to other galaxies will progressively continue
to start new civilizations for the following 10 billion years,
and after that our expansion will be complete. 10 billion years
may sound like a lot, but the universe
will last for trillions of years. Future humanity will have plenty
of time to enjoy even the most distant galaxies. Armstrong and Sandberg calculated
that at speeds between 50%
and 99% of the speed of light, the probes will reach
116 million to 4 billion galaxies. The higher the speed,
the more galaxies the probes can reach
because the universe is expanding at an accelerating pace. And as time passes,
an increasingly large number of galaxies become
forever out of reach. If we can't find a way
to sidestep the speed of light limit. Final considerations. And now that every step is complete,
you know how to take over the universe. You don't need to do everything
exactly this way, though. This paper proposed
many possible designs and methods at each step,
but there are certainly many more ways to go. Moreover, Armstrong and Sandberg
used conservative assumptions. The real designs
will probably be better. The point of the paper
was to illustrate that the feat is in principle,
possible with cosmically insignificant amounts
of time and energy. One additional point
motivating the paper is that since spreading
through the universe doesn't require a lot of resources,
that means that the Fermi paradox is a lot sharper than we imagined. There are millions of galaxies
that could have potentially reached us by now,
and yet we don't see any alien colonization projects
in our local neighborhood. This could simply mean that
there's pretty much no one else out there. Or another answer could be
the one given in the grabby aliens videos. If we could have seen aliens,
they would be here now instead of us. If there are indeed aliens out there,
that means our time to begin expanding into the universe
is even more limited than we previously thought. Not only is the universe expanding
at an accelerating rate, making more and more galaxies
forever out of reach, but aliens might also be out there
grabbing galaxies instead of us. So what are we waiting for? Let's go and do it ourselves. Let's take over the universe!
