We’ve occasionally talked about what it
might be like to be the last sentient life left standing at the End of the Time and looking
back at your once glorious civilization. But what if we spin the time dial even further
ahead in time… set it all the way past the End of Eternity, until that last person couldn’t
even remember their past civilization? It’s been a year since we did the first
episode of the Civilizations at the End of Time series, Black Hole Farming. To my surprise, that episode went on to become
the most watched one on the channel, so it seems like it deserves a sequel. It probably shouldn’t have been too surprising
since the end of time and civilization is something upon which we ponder and speculate
quite a lot. It is also the conceptual center of numerous
stories both in and out of science fiction. The best of these, in my opinion, is the short
story “The Last Question”, by the grand master of science fiction, Isaac Asimov. Since this episode is sponsored by Audible,
and is our first occasion working with them, we’ll spend a little time discussing Asimov
near the end, and try to keep it spoiler-free because you can pick up "The Last Question”
by using my link Audible.com/Isaac, or click on the link in the description below. That gets you a FREE audio book and a 30 day
free trial of Audible. But the problem with doing a sequel to a video
about the End of Time is that there’s not really supposed to be a sequel, unless you
have a time machine. As I said in that discussion, there are things
we could do to keep life going even after the Black Hole Era, but to do that, we should
first recap some of what we have already discussed last time, then introduce concepts like Boltzmann
Brains, and the Margolus–Levitin Limit on quantum computing and reversible computing. We also need to discuss quantum tunneling,
proton decay, iron stars, and the fate of the Universe itself. We’ll try to keep the technical aspects
to a minimum, but they are there, and this is going to be a fairly long episode, so as
always, it might not be a bad idea to grab a drink and snack before we start. To recap what we explored in the original
episode, a black hole can be tapped for energy in three principal ways. The first and easiest is to drop mass into
the thing and capture its kinetic energy as it plummets -- like attaching a rock to a
string wrapped around a generator and tossing the rock off the side of building. The second is to use its rotational energy
like a big dynamo; slowing down its spin in exchange for electricity. The third method is to tap into the Hawking
Radiation that they are believed to emit. For very small black holes, there is actually
a much higher amount emitted at a given time than from bigger ones. Any black hole gives off a large chunk of
its mass energy as Hawking Radiation, but while the big ones have more overall, double
the mass, double the energy, they give it off far more slowly. If you double the mass, you also quarter the
energy it gives off for any given time period. The amount of power is also constantly rising,
since in the absence of sufficient new material upon which to feed, the black hole’s mass
shrinks, and smaller black holes give off more power. In an ideal scenario, you would make your
own black hole with the power generation rate you wanted and just keep feeding it matter
to maintain it at the same level of mass. You could make one that masses about a billion
tons, gives off a billion watts of power, a gigawatt, and lives for about a trillion
years, giving off that amount of power the whole time. Ideally, you could feed matter into such a
black hole indefinitely, replacing whatever was burnt off. That’s roughly the power output of our bigger
nuclear and hydroelectric plants, and you’d only need to feed it about a kilogram of matter
per year to keep it going indefinitely. “Indefinitely,” is a theoretically incorrect
term in this context, however, because the entire galaxy masses out somewhere near 10^42
kilograms, enough to feed such a black hole generator for a million, million, million,
million, million, million, million years. Not bad, considering humanity’s basically
been around for a million years, and we will start running out of natural starlight in
the Universe in a few million, million years. Yet a naturally occurring black hole lives
even longer than that, and does so by trickling its power out far more slowly. We discussed harnessing power from such behemoths
in the original episode, by dropping matter into them or tapping their rotational energy,
but this won’t let you get all of their energy. Whereas a smaller black hole evaporates via
Hawking Radiation quite quickly, naturally occurring ones do so at such a slow rate that
it could take eons to gather enough power to flip a single switch. Once you’ve exhausted all of its rotational
energy, which is enormous, and dropped in every last bit of the spare matter you have,
all that’s left is that Hawking Radiation. However, running an entire civilization on
levels of power that you’d need sensitive equipment to even detect is probably impossible... ...Impossible for ‘biological’ life anyway. Once you start abandoning neurons in favor
of computer chips, the game changes a lot. Doing so means that now, hypothetically, you
can take advantage of those longer-lived black holes. They give off just tiny trickles of power,
but it takes a lot less energy to run a computer-based human and you would also be able to slow down
the speed of consciousness. It doesn’t matter if it takes you a trillion
years to complete a sentence when everyone else experiences time just as slowly and the
outside universe is a pretty dead and boring place anyways. In part, that’s what we meant about these
being civilizations at the end of time, because our classic view of time starts meaning less
and less. Right now, time is a pretty constant thing
for us that we all experience at more or less the same rate. Yet time slows near black holes, so you can
move in close to them to slow things down too, and if you are also tweaking your rate
of thinking down to a glacial pace, you are experiencing periods of time long enough for
stars to live and die like ticks on a clock. This only tells us what we can do when we
run out of other power sources though, how to keep going when you run out of stars. What we explored in the original episode however,
was how something called the Landauer Limit, which demonstrates that the theoretical maximum
calculations you can get out of a given amount of energy depends on the temperature. The colder it is, the more efficient your
computers, if that is their limit; half the temperature, double the calculations per joule
of energy used. This massively changes the dynamic, because
suddenly you are not striving to survive after the stars have burned out, but intentionally
hoarding your energy until after then because you can use it way more efficiently. As the Universe expands, it gets cooler and
cooler, and right now it’s about a hundredth the temperature Earth is; meaning a computer
out in the void should be able to do a hundred times the calculations for the same amount
of energy as one can here on Earth. Quintillions of years in the future, when
the whole Universe is not even a thousandth of that temperature, you get way more processing
power, or thinking and living (to put it in human terms), per unit of mass or energy. Entire planets and planetary populations could
be run in real-time on less energy than it takes to power whatever speakers you’re
currently listening to me on. So a civilization might gather up all the
matter that it can, storing virtually all of it until the temperature drops to whatever
the minimum is that they can function on. From a practical standpoint, a given switch
in a computer will need a very long time to cool back down after you use it in order to
to exploit that ultra-low temp computing. This actually works out fine since the biggest
black hole gives off power so slowly that you’d need trillions of years’ worth to
power a lightbulb for an instant. These factors coincide well if we have very
durable equipment that requires minimal maintenance, since external objective time is almost meaningless
in a dark, post-stellar Universe. Internal subjective time would be everything,
and to the participants things would seem quite normal. In such a scenario, the period of time after
the stars burn out is no longer some dead place where at best the last remnants of civilization
are barely holding out for just a little while longer. It could be hosting mega-civilizations that
would not even notice a trillion years going by in objective time, while enjoying trillions
of trillions of years of subjective time. You could basically have a civilization living
around a black hole a few kilometers across that dwarfs a full-blown Kardashev 3 Galactic
Empire in every possible respect, and that also regards the power output of a light bulb
in the same way we do the entire Sun. Nor would each of these black holes necessarily
host an entire civilization, they might opt to run smaller communities at a higher rate
of subjective time, networked with other black hole communities to form a civilization. Time lag for communications between these
is not too big a deal, since it might take light a thousand years to reach your nearest
neighbor, but that might seem like normal conversational speed to you and them. A trillion, trillion years in the future you
might be around a black hole somewhere chatting with a friend who was the same but thousands
or millions of light years away, experiencing no more subjective lag between your environments
then you do on the phone or in a chat room, presumably sharing some simulated environment. With subjective time slowed down so much,
things like a galaxy spanning internet finally become possible even if you are still bound
by the speed of light. That was what we discussed last time, as a
reminder for those who saw that. But it gives us some questions. First, how can you possibly maintain your
equipment for those kind of timelines with virtually no energy? Especially if there is proton decay. Second, what do you do afterwards? Is it all done then or can life go on? The answer to the second, if you can solve
the first, is “Yes, kind of”. The biggest black holes can live almost 10^100
years. If you can somehow support yourself on that
near infinitesimal trickle of power, you will notice it begins to rise near the end, and
you will occasionally notice your neighboring civilizations around their own, smaller black
holes surging up and eventually exploding. Near the end of life for any black hole, it
will spike up to energy levels that are quite classically visible, for the last month it
will be bright enough to light a whole planet, and in the end, nearly as bright as a star. That’s a lot of power to run one last big
party off of to say good-bye, more than enough to re-simulate our modern civilization many
trillions of times, but it’s also a nice chunk of energy to fuel something afterwards. That afterwards is our main interest today. Let’s discuss the maintenance issue real
quick. We can’t build stuff that lasts more than
a few years or decades nowadays, not when it comes to complex machinery, so trying to
build stuff to last trillions of years with little to no maintenance sounds kind of absurd…
and it certainly is in the context of our current technology, I don’t want to sugar-coat
this problem. Yet we can potentially benefit again from
slowing down time. Real time too, not just subjective time. We can slow down subjective time for thinking,
by just running a computer slower, various decay processes still occur at the same rate. But time slows down as you get closer and
closer to a black hole, and for the very largest black holes you can get quite close before
being harmed by tidal forces. This lets you slow down the rate at which
decay is occurring in chemical, mechanical, electronic, or even biological systems. Of course they are only going slow from an
external view, in many ways a black hole is just an implosion taking place in a slowed
down region of space so that it takes eons to witness. Again, it’s all about subjective time, but
that’s all that truly matters in a Dark Universe where not much is happening. However, we have another big advantage from
that dark and boring Universe. Damage and decay tend to be the result of
external events, and your machinery wouldn’t experience a lot of erosion, oxidation, or
decay when it exists in an empty void chilled down to a micro-Kelvin. You also have trillions of years to figure
out how to build stuff for the long term. Not to mention all that time to figure out
alternatives like jumping into another, younger universe, or tapping vacuum energy. You might just flat out learn how to violate
energy conservation or tell entropy to take a hike. Solve any of those and you can have civilizations
that last a very long time. Of course, one big problem with matter is
that on these kind of timescales, just about everything has to be considered unstable and
radioactive. Carbon-14, or radiocarbon, is very handy for
radiocarbon dating because it only has a half life of about 6000 years. You wouldn’t want to build anything out
of radiocarbon that you wanted to last millions of years because it will start turning into
nitrogen on you. Many other substances, while we call them
stable, still have half-lives that are long, but not infinite. This is made worse if proton decay occurs,
but if it doesn’t, on long enough timelines, longer than even the black hole era, we do
have to worry about all matter turning into iron, which we’ll get to later. Overall though, you just have to worry about
slowly losing matter to unavoidable losses, be it collisions or evaporation or decays. It’s all fixable, but you need to be able
to do it with virtually no energy, because you have virtually no power. Once again, time slows near black holes, so
you might be able dance around the issue that way too. Now, we also have proton decay to consider. Under the Standard Model, protons last forever,
but in some other models, they do decay somewhere in between 10^31 to 10^36 years or longer. Either of those are a near eternity compared
to the Stellar Epoch of the Universe, but it’s shorter than any naturally occurring
black hole would live, or even a small one with a dwarf planet’s mass instead of a
star. This doesn’t change things too much if our
civilization has mastered making black holes they can actually add matter to. They wouldn’t be able to use Hawking Radiation
from bigger ones because they couldn’t exist that long without all their matter decaying,
and would be limited to just using their rotational energy and artificial, smaller black holes. They still operate like the other black hole
civilization, except they’d generally be trying to prevent black holes from forming
naturally or merging. We may, however, be able to make further use
of decaying protons, since protons are assumed to decay into pions that turns into gamma
rays, a nice power source, and positrons. The positron is the antiparticle of the electron,
and perhaps you could alter everything to run off Positronium instead. Positronium is a quasi atom composed of a
positron and an electron orbiting each other, instead of an electron around a proton as
in hydrogen. It is perhaps possible to build new types
of molecules out of it, allowing you to continue on even with proton decay. In the normal model for the end of the Universe,
things keep expanding forever with large clumps of matter bound together by gravity, and the
rest all carried so far away they eventually redshift over the cosmological horizon. Best guess right now is that our own galaxy,
and our nearest neighbors, will eventually merge into one big galaxy that will stay together
and that’s it... that is, barring artificial intervention of sorts, which we’ll get to
shortly. In this version of things, all matter eventually
ends up in black holes, dead stars, or objects too small to naturally be either. We can live around those dead stars for a
very long time too, but they eventually cool down into super-dense, super-cold objects
with so much gravity we’d have a hard time mining them usefully. They will have another use for us later, however,
in the formation of iron stars, but that takes a very long time even compared to the Black
Hole Epoch. We can't be sure we have that much time though,
and we have a theory called the Big Rip which might prevent us from even getting to the
Black Hole Epoch, let alone the Iron Star Epoch. We don’t know much about what makes the
Universe expand, other than that it appears to be accelerating, which is why we call the
force doing this Dark Energy, we are not illuminated yet on what it is. You will have heard about a scenario where
this accelerated expansion rips the entire universe to shreds in just 20 billion years. As an FYI, that period was calculated using
an arbitrary round value for w, the relevant constant, of -1.5. We don’t know what its value is, just that
it’s probably -1 or close to it, but if you plug in -1.5 you get about 20 billion
years left, stick in -1 and you get infinity. There is no theory saying the Universe ends
in 20 billion years; it was just an example in the original paper. If it were -2 in the example, it would be
ten billion years, if it were -1.1, a hundred billion. But if this theory is right, and w is not
exactly equal to -1, the force acting to expand the universe would eventually grow strong
enough to override the gravitational force existing between all galaxies, then between
all stars, then strong enough to override the gravity holding stars and planets together. Taken to its conclusion, it finally reaches
a level powerful enough to override the electromagnetic forces binding molecules together, and eventually
even nuclei themselves. However, the thing about quarks, and the strong
nuclear force that binds them together, is that when you pull on two quarks, to rip them
apart, you have to exert so much energy to do it that, that you actually end up spawning
two new pairs of quarks, so you get this huge new outpouring of new matter everywhere. It’s a bit of a Hydra thing. Slice up a quark pair and get two more, that’s
also one way to convert energy into matter. The theory gets a bit uncertain at that point
since it operates under General Relativity, which is very iffy at the atomic scale, and
of course our understanding of Dark Energy is not terribly precise or ironclad either. Right now it’s a bit of black box, we know
what it does but not how it works or where it comes from, and we can't rule out that
a better understanding of it might open a new energy source for us. See the Dark Energy episode for more discussion
of it. Regardless of what happens when you get to
the atomic unbinding stage, nothing would be around to witness it so it wouldn’t matter
to you. If your scientists determine that it is the
correct theory, you then figure out the actual timeline you have left and ration resources
accordingly. If you’ve got 20 billion years you really
have no reason to conserve anything. I’ve heard folks suggest you could make
a very large black hole and tuck your civilization inside it for protection, but I’ve also
heard the Big Rip takes out black holes too. I’d say a cosmologist could provide a better
answer, but we have no proper theory for quantum gravity, so it’s probably a guessing game
right now anyway. That end expansion is very fast too, so you
wouldn’t duck inside a black hole to buy a little more time or anything. Assuming the Big Rip isn’t the case though,
civilizations looking at real long term solutions, probably want to conserve matter and energy
as much as they can, and probably hoard it from wherever they can. It stands to reason, that if you are planning
to keep your civilization around as long as you can, you will start hoarding matter so
that it doesn’t get burnt up uselessly in stars or fall into black holes bigger than
you want or get ejected out of the galaxy. This is one of the reasons we say in the Dyson
Dilemma that civilizations that don’t want to expand their numbers might seem to expand
anyway, as they journey outwards not to colonize other solar systems, but to stockpile their
matter instead. Like squirrels hoarding nuts because winter
is coming. Big stars do make valuable heavy elements,
but supernovae are not efficient methods for that, and odds are civilizations that want
more of those would prefer to use a giant particle accelerator instead, as we discussed
in last week’s Dyson Spheres episode. I also mentioned there that it is possible
to move planets or stars. However, it is also possible to move galaxies. In all of these cases, the method isn’t
high tech, just very big. The Great Wall or Pyramids were huge tasks,
but hardly high tech. While technology can possibly make it much
easier to do, or offer you other methods, fundamentally it’s not complicated, just
an application of the maxim “if brute force isn’t working, you’re not using enough
of it.” If you don’t mind waiting a billion years,
you can place a ton of thin mirrors near a star and have them bounce the light in one
direction, accelerating them up to quite high speeds, as explained in the Shkadov Thrusters
episode. You can accelerate that process by using the
methods we discussed in star lifting to spew out increased amounts of solar wind, like
a rocket engine flame. Do this to a galaxy’s worth of stars and
their own gravity will bring that galaxy along. We will discuss this more in the future, but
the summary form is that you are not limited to your galaxy’s resources alone, or even
to those of the dozen or so near enough not to be pulled apart from us by the expanding
Universe. I am frequently asked how far outwards I think
we could ever hope to colonize, and the answer is it depends on how fast your ships can go. You’ve probably heard of Hubble’s Constant,
usually measured at about 70 kilometers per second per megaparsec. I try to avoid using parsecs on the channel
so it is about 20 kilometers per second per mega light year, or 2 centimeters per second
per light year, whichever you find easier. That’s how fast something is traveling away
from us, from all the space emerging from every point in between us and it, as the Universe
expands. So a billion light years away would be 20,000
kilometers per second, which is about 7% of light speed. You need a ship that can go at least that
fast to reach a galaxy that far, far away. I generally place this as the practical point
of expansion, since I figure you will eventually run into someone else who would appreciate
you not setting up shop in their galaxy, even if they don’t exist yet. Leave now on a billion-light year journey,
and when you arrive, a planet that was just forming when you left might be the capital
of an interstellar empire. And while intergalactic warfare is at least
vaguely plausible in a no-FTL universe, inter-supercluster warfare really is not. You could also get a galaxy to move at this
speed back toward you, but probably not much faster, so the million or so nearest galaxies
closer than about a billion light years from us is probably all the mass available to a
civilization. We’ll go with the rounded value of 10^48
kilograms, keep that in mind for later, but that’s more or less your upper limit, and
it could be steered into a pretty compact volume not much larger than our galaxy. Any tighter than that and the combined mass
would form a galaxy-sized black hole. Some of that matter, however much you hoarded,
would be acting as fuel. Indeed, it probably almost all of it would,
eventually, but we can assume a lot of it would be used for making computers and memory. The processing power permitted under classical
computing, when temperature is your true upper limit and you’ve got solar systems worth
of mass to build your computers out of, is mind-boggling, but we have some options that
might let us squeeze even more calculations or simulations out of a small amount of energy. We talked about Quantum Computing earlier
this year, and tried to dispel some of the myths about it which elevate it beyond a very
powerful tool into almost magical status, and at some point we’ll need to do the same
for Time Crystals, but, unsurprisingly, a lot of folks have wondered if these options
let you blow past even the titanic processors allowed under classic computing, or potentially
do entropy-free calculation, Reversible Computing. Last time, we discussed how Landauer’s Limit
on conventional computing is based on temperature. It is a hard physical limit that tells us
that no matter how much we improve computing we can’t beat that. Not with conventional computing at least. As I said in the Quantum Computing episode,
we never want to regard that technology as a magic wand, and it is way too new for us
to discuss it reliably. That’s even more true for Reversible Computing,
specifically physically reversible or isentropic computing, where you could do all your calculations
essentially energy free by undoing the process afterwards. This is usually thought to be impossible and
actually where Landauer’s Principle derives from. But we’re not sure it actually is physically
impossible. There are some reasons to think otherwise,
and trillions of years is a long time to figure out how to do it or get close to it. If that turned out to be possible though,
it turns out we have another limit, of a different kind, that controls the speed we can reverse
calculations at. This derives from the Margolus–Levitin theorem
that shows that even reversible computing and quantum computing are fundamentally limited
to no more than 6x10^33 operations per second per joule. The more physics savvy of you might have just
twitched. Yes, that was seconds per joule, not joules
per second. It is saying that, if you can keep using the
same energy to run computations constantly, that this is the maximum speed you can run
them at. Converting that into matter, at about 10^17
joules per kilogram, and dividing by our usual assumption of about 10^16 Hz of processing
to emulate a human brain, we get 6x10^34 people being simulated per kilogram of matter…
which was about the same as what we got from a full-blown solar system spanning Matrioshka
Brain, an MB, and which would conveniently fit in your pocket rather than an entire solar
system. If you saw the episode on Matrioshka Brains,
you might recall that it could hold more emulated minds than an entire K3 civilization could. As a reminder, a K3 civilization is one that
hasn’t just populated every solar system in a galaxy, but also turned them all into
Dyson Spheres. Now since this presumably does not need energy
to run on, or rather doesn’t expend any, our 1 kilogram pocket MB could just sit there
emulating billions of trillions of trillions of humans forever, enough to normally populate
an entire supercluster of galaxies converted into Dyson swarms. One eternal engine of thought for one kilogram
of mass-energy. Earlier I mentioned we could possibly get
our hands on as much as a supercluster of mass, 10^48 kilograms, a trillion, trillion,
trillion, trillion kilograms. At this sort of scale numbers start feeling
a bit meaningless, but you’d be talking about a potential real-time population of
10^83 people, more if you either run them slower or can get that processing figure per
person down. That is more people than there are atoms in
the Observable Universe. You can add on 5 more orders of magnitude
if you want to assume the entire Observable Universe was converted, not just the matter
in the nearest billion light years, or knock 5 or 6 off if you want to limit it to the
galaxy. We don’t know that such a thing is possible,
but that is the hard limit for that in much the same way Landauer’s Limit is way beyond
what we can do now with computers. It represents a hard limit on what we can
do conventionally. I get asked about reversible and quantum computing
a lot after the original episode, so I wanted to address the option. We do have to wonder what such a computer
would be used for, the obvious being to keep running simulations of people, digital consciousnesses. Though an alternative is to devote all that
processing power to trying learn how to break the Laws of Thermodynamics and reverse entropy,
a very important question for any civilization that wants to live forever, and the Last Question
you’ll probably be asking, if you want to see the other side of Eternity. Keeping to more classic views of computing
and the Universe though, we still have options for surviving the Black Hole Epoch. Once those all die, and basically explode
(it’s always good to remember that’s how that goes down) all the Universe is a frozen,
desolate, void of gas at near vacuum levels and a few leftover dead stars or planets. If you were some civilization that spent the
last 10^100 years living around a leftover galactic core black hole, and the last trillion
or so of it living around the much smaller and more energetic one it became, storing
up that energy, you’d have noticed the occasional object drifting around that was just a bit
warmer than the background temperature of the Universe. You’ll know that these used to be neutron
stars or white dwarfs that long since cooled off, but haven’t cooled off completely. You recognize one as good old Sol, our home
star, long since turned red giant, then white dwarf and, finally, black dwarf. Nobody ever disassembled it or shoved it into
a black hole for fuel, because it was our home. It gave us life back at the dawn of time and
we will return to it now, at the end of time, to let it give us life once more. The reason it is just the barest degree warmer
than the Universe around is that inside, incredibly slowly even compared to black hole timelines,
particles are slowly transmuting into iron and releasing a little energy when they do
this. Iron is the last stopover point for matter. Heavier matter eventually decays into it and
lighter matter fuses up into it. This happens superfast in big stars, but here,
in our dead Sun, it occurs over time periods of 10^1500 years. And every time such a transformation occurs,
a little energy is released. How a civilization would possibly tap such
tiny amounts of power, let alone maintain their equipment while doing this, is beyond
me. Even doing it for the Hawking Radiation of
a normal solar mass black hole pushes plausibility. Yet, at least on paper, under known physics,
it is conceivable. If they can somehow gain power out of this
tiny, Earth-sized remnant, and operate computers off it, they can keep going, they can continue
to exist on this Iron Star for timelines that look at the whole prior Universe, even the
Black Hole Epoch, as so much less than an eyeblink. And we’re still not done yet. Once this white dwarf turned black dwarf slowly
mutates into a pure iron star, it still will not have reached its lowest energy level. That Iron Star will eventually collapse into
a neutron star, at an estimated timeline of 10^10^76 years, coincidentally almost the
same as the 10^10^77 possible unique states for the Universe, or total alternate Universes,
that we discussed in Infinite Improbability Issues. A very great deal of energy will be released
when that collapse from Iron Star to Neutron Star occurs. This means even more lifetime for those there,
if they have somehow survived that long. Alternatively, Iron Stars might turn into
Black holes even sooner, a mere 10^10^26 years, and you restart yourself. That black hole that forms, being of less
than one solar mass, will once more give off only a trickle of energy, but it would seem
like a banquet feast compared to what you were used to back in the Black Hole Epoch. Finally though, it will end, after another
near eternal golden age. It slowly rises in power, until it gives off
its last gasps, shining nearly as brightly as the stars that disappeared so long ago,
and then that is essentially it. If you haven’t figured out how to keep going
in the face of entropy by now, it is too late, but you will get that final second Black Hole
Epoch, or Neutron Star Epoch, depending on how the physics of that works out. And yet, it is not necessarily the end of
intelligence, even if it is the end of civilization. If matter is required to store information,
and you’ve been accumulating so much of it, you’ve probably also been discarding
extra bits to keep going a while longer. If the Sun went out, you could stay alive
a while longer by tossing your furniture and books into the fireplace, and while you might
not be able to bring yourself to toss your favorite book into the fire to buy a few more
minutes, all sorts of old manuals and reference books might find themselves in there. Odds are pretty good such civilizations would
do the same, maybe trading every memory for a little more time, maybe just old tax returns
and astronomical tables sacrificed to live a while longer. In the end, they go, sooner rather than later
if they want to keep a lot, but they can keep some in reserve almost to the end, because
the power levels will rise for a black hole near the end, or for the collapse of an iron
star to a neutron star. Either way, this is when time, as any meaningful
measure, has truly come to an end, Eternity has come and gone and taken with it any civilizations
and their records. But again, not necessarily intelligence. We call it the Heat Death of the Universe,
even though it is terribly cold, because everything is in thermal equilibrium, there is no longer
any source for energy. Entropy and the Laws of Thermodynamics have
finally closed the book on things. Yet inside that random chaos it is possible
for occasional bits of order to emerge. If I take a deck of cards and put it in order,
then shuffle it, it becomes disordered, more and more every time I shuffle it. But if I do that enough times it will return
to its original state. It could happen at anytime, but, on average,
for a 52 card deck, it should take approximately 52-factorial shuffles, or 52 times 51 times
50 times 49 etc all the way down to 1. In this case, if I shuffled that deck once
every second, I should expect to reset it in about 10^60 years. This may seem an impossibly long time period,
but on the timelines we have been looking at today, that’s actually rather modest. Were I to use only one suit of cards, just
13 cards, in order from Ace to King, that would be more like 200 years, something which
you might see in your own lifetime of shuffling. Likewise, if I used a larger deck it would
take far longer. Back in Ludwig Boltzmann’s day, we knew
about entropy, but thought the Universe was steady state. In a closed system like that, no matter how
big it is, just like shuffling a deck of enormous cards, eventually your particles all reset,
and will reset to something close enough far sooner. When all is chaos and random action, even
processes which normally build up entropy become effectively reversible, so long as
there is a finite chance of them occurring. And in the Infinite Improbabilities episode,
we discussed all the weird things that can happen when we begin giving incredibly tiny
yet still finite odds near infinite time or space to work in. One of those weird things is the Boltzmann
Brain, that even in a Universe reduced to total entropy, out of that chaos will emerge
a random pattern of matter that is a thinking creature. Everything is bumping around chaotically and
just happens to create a random pattern that is, for instance, a big sentient supercomputer
with a nice nuclear reactor attached to it to run it until components or fuel decays. Perhaps even a nice habitat with plants inside
it, with a person to eat them... a little Eden if you will. After eternity, in this frigid random soup,
these minds could just keep popping up. We do not live in a steady state universe,
ours is expanding, so we are pretty much guaranteed no total resets of entropy, but Boltzmann
Brains can exist and, indeed, can come to be in other Universes where the physical constants
might have values that normally preclude life, or even simple chemistry, from occurring. Indeed, in some universes, they’d probably
be the only kind of life that could exist. Over an infinite period of time, anything
that can happen will happen, including a stable and long-lasting Boltzmann Brain, which might
sit around contemplating ways to deal with entropy. Such an entity would not remember us, though. It would not know or remember that there ever
was a Universe beyond the frozen sea of chaos all around it, but it would be alive and thinking. And since, if one can exist, there is an even
smaller chance two could exist near each other in time and space, or three or more, we do
have a chance for a Civilization after the End of Time. … And you only need a chance... This is as far as we go looking into the future,
so while we might do some more episodes on Civilizations at the End of Time, they’ll
have to be prequels, not sequels. Time can’t really be said to have an end,
and, in a lot of ways, we aren’t talking about the end of time, but our general fight
against entropy itself. It’s a long, drawn out war, with a lot of
battles along the way, even before the death of our own sun, which, as we’ve seen in
this series, is more of a prologue than epilogue to civilization. I mentioned near the beginning that the episode
was dedicated to Asimov and his short story “The Last Question”, which is focused
on that theme and is generally voted his best short story. It starts off in modern times and rolls all
the way on to the end of things, charting Asimov’s vision for the future of humanity. It’s been adapted a number of times, including
a performance by Leonard Nimoy, and has also shown up in five or six Asimov short story
anthologies. Even 60 years later, the story manages to
talk about computers and the future in surprisingly accurate ways and, where it misses the boat,
it highlights how new we are to this technology and how much room to improve it we have in
the the very long time we have before the stars start going dark. As the channel approached 100,000 subscribers
we had a lot of comments and jokes about how we might get a sponsor, and, as some of you
might recall, I said I probably wouldn’t accept one, unless it came from someone like
Maxwell House, Starbucks, or Audible. I am a very big audio book addict and have
been since I was a kid, and I’m usually listening to one when writing or editing these
episodes. As it turns out, Audible approached me a couple
weeks back and offered a sponsorship, essentially on the grounds that we already talk about
science fiction novels a lot anyway, so it was a pretty natural fit and, as a long time
customer of theirs, I’m glad to welcome them on board as a sponsor. I’d already written this draft of this script
and talked about “The Last Question” in it, so, starting off by recommending my favorite
short story by my namesake, Isaac Asimov, seemed very appropriate. That short story is available on Audible by
itself, or in the anthology “Robot Dreams”, and you can pick up a free copy today - just
use my link, audible.com/isaac, or click on the link in the description below, to get
a FREE audiobook and 30 day trial, That’s audible dot com slash I_S_A_A_C. I’m certain you will enjoy that story, but
if not, you can swap it out for free for any other book at anytime, and it’s yours to
keep whether you stay subscribed to Audible or not. Next week, we will be returning to the Fermi
Paradox Great Filters Series to look at possible conditions that might make life on Earth-like
planets a lot less likely than we tend to think, in Rare Earth. The week after that, we will take a look at
the concept of Force Fields, and see if there are any realistic options for that under known
science, as well as discuss some under-explored uses and applications for such technology,
if you’ve got it. For alerts when those and other episodes come
out, make sure to subscribe to the channel, and if you enjoyed this episode, hit the like
button, and share it with others. Until next time, thanks for watching, and
have a great week.
i wanted to put this video, but it was to long for the subreddit. this channel is full of videos from 20 minutes to 1 hour and i love it
Isaac Arthur is one of the best youtubers out there!
He also has all his content in podcast form, with or without background music, since the videos are really just slideshows and never produced to be necessary to understand
I highly recommend the "upward bound" series to see what we can do with reasonable budgets and current technology if the media will stop drooling over musk and his rockets.
Hell yeah Isaac needs more love if you l handnt seen his videos yet. I recommend you listen to his stuff during a drive or whenever gaming because this man is gold mine of knowledge.
Just watched the video and fuck it's so interesting. I'm too ignorant and dumb to understand it deeply but I'm still captivated by all of these possibilities pointed out in the video, these subjects and the depth he goes to explain them just become mindboggling to me, because it almost sounds like magic, as if he were talking about the lore in a video game, but no, it's real and to some extent theoretically possible.
Thanks for sharing, just subscribed as well.
yea this isn't scary at all
Seems interesting enough, but the narration and pronouncing 'R's as 'W's gets really grating fast.
That channel has been one hell of a rabbit hole for me today.