Civilizations at the End of Time: Dying Stars

Civilizations at the End of Time: Dying Stars


This episode is sponsored by Curiosity Stream
Science tells us that the Universe is almost 14 billion years old, yet will live many trillions
of years more before the last stars die out. But that is a future that will never happen… So today we return to the Civilizations at
the End of Time series after a year long hiatus. Today we’ll be exploring what civilizations
might do as their own suns begin to burn out, and what options they have on the table to
extend their existence after that. We’ll also be discussing the Supernova Engine,
one of the most extreme forms of Stellar Engineering allowed under known physics. I should also warn viewers that while the
Civilizations at the End of Time series is weirdly our most watched series, its episodes
are always composed of concepts we’ve developed in more detail in other episodes. They’re not really meant to be standalone
episodes, and I’ll reference some relevant episodes which you might want to consult,
so that when I start talking about moving stars for instance, you already know and understand
the physics involved in that. This month we’re also celebrating Douglas
Adams’ Hitchhiker’s Guide to the Galaxy series. Unsurprisingly the second book of that series,
“The Restaurant at the End of the Universe”, is our focus for today. Speaking of restaurants and food, we’ve
a lot of concepts to cover so grabbing a drink and snack for today’s show is definitely
a good idea. In Hitchhiker’s Guide we have the Restaurant
at the End of the Universe and also the Big Bang Burger Shack, as both are events that
any civilization with time travel would certainly want to see. But while we know when the Big Bang happened,
as it was a fairly singular event, the End of the Universe is a much hazier concept. The distant future of the Universe is not
something we can speak of with much certainty just yet. At the moment the weight of evidence tilts
toward an eternal expansion. Dark Energy will expand space so that all
but our nearest neighboring galaxies are so far apart that they will fly over the cosmological
event horizon, gone forever. At the same time our galaxy and those neighbors
will merge together into one big clump. This is not a very distant future on the epic
timescales of this channel, either. That galactic merger isn’t a few billion
years from now but something that’s already happening. Our galaxy and a couple of our bigger neighbors
like Andromeda and Triangulum have been eating smaller neighbor galaxies for a long time
and will merge with each other in just a few billion years. During that same time, we will have noticed
a lot of the more distant galaxies we can presently barely see will have disappeared. Even though we’ll be able to see further,
because space is expanding everywhere constantly, and the greater the distance from us, the
greater the rate of expansion. At far enough distances, that expansion will
happen faster than light can cover the new distance. In a hundred billion years or so, only those
galaxies just outside our local group will still be visible to us, and soon they’ll
fade away too. But our future merged galaxy will still be
running strong at that point, and star formation will be slowing a little bit but not by too
much. Our Sun will be long dead by then but our
nearest neighbor, Proxima Centauri, will still be young in its own much longer life. But eventually it too will die. New stars will form less and less often, until
sometime many trillions of years from now, all that will be left is a lot of cooling
stellar remnants. Since stars are critical to life, we might
think that the death of that last star is the effective End of the Universe. All that will remain will be a slowly expanding
and cooling Universe of eternal darkness. This is called the Heat Death, because even
though it will be quite cold, in physics we define heat as the entropic state of energy
rather than a specific temperature. There are some alternative cosmologies for
the fate of the Universe that are quite hot though, such as the Big Crunch, essentially
a reversed Big Bang, and perhaps also something called the Big Rip, in which expansion continues
to accelerate until it tears apart even atoms themselves. As of now, heat death is the most agreed upon
theory. All stars will eventually die. While you might think that the last one’s
death will signal the end of time in a meaningful sense, as we saw in Black Hole Farming and
Iron Stars, this is not so. Civilization can continue past that point,
and possibly even thrive. More to the point, this death will not be
some spectacular explosion, just a slow turning-down of the lights. The longest lived stars are the least massive
ones, and as available hydrogen gets scarcer in those final days, these smaller stars will
tend to be the ones forming. Indeed, tiny, dim red dwarfs will eventually
become the only stars in existence, since they persist for a very long time and will
make up an increasing percentage of new stars near the end of things. And they don’t explode. In fact, very few stars do, just the most
massive ones. Big stars run out of fuel and they enter a
red giant phase, but the very smallest do not even do that, they will probably get hotter,
turning into blue dwarfs. These stars take a very long time to evolve,
and the Universe isn’t old enough to have any yet. Eventually, in their final death throes, they
will flash into white dwarf stars. Finally, at the end of their lives they will
cool into black dwarfs. The end of the Universe will not be marked
by a discreet moment in time, nor is the death of most stars. The biggest stars, and tiniest fraction of
them, will undergo a red giant expansion and a supernova, with the most massive of these
turning into black holes and the smaller ones into neutron stars. We’ve often discussed ways to live around
black holes, and neutron stars also slowly cool. Indeed what we call a pulsar is merely a relatively
young neutron star that’s still rather hot and active, and happens to be tipped at an
angle we can observe the pulsar beam from. Far more stars, including our own Sun, will
expand as a red giant, then lose their outer layers and fall into a white dwarf that slowly
cools off. And even more of them, especially as the Universe
ages, will skip the red giant phase in favor of being a blue dwarf. We’ll discuss stellar engineering options
in a bit, but let’s start by discussing the slow cooling off of white dwarfs, neutron
stars, and indeed black holes. We’ll focus on our own Sun as our first
example. Right now it’s about halfway through its
lifetime on the main sequence, burning hydrogen to produce helium and light. The term main sequence implies it is the longest
chunk of its life but this tends to falsely imply a fairly static and long period followed
by something short and violent and final. Quite to the contrary, our Sun is slowly warming
up with time. It will be about 10% brighter in a billion
years and life on Earth will begin to die as the atmosphere and oceans are stripped
away. About 5 billion years from now, when our local
galaxies have essentially all merged or are just finishing that up, the Sun will exhaust
the hydrogen in its core and will expand into a subgiant and then a red giant. It will proceed through the various phases
of that process for hundreds of millions of years, blowing off matter into a planetary
nebula before leaving an exposed naked core that’s about 100,000 Kelvin. Finally, it will become a white dwarf. Bigger stars will evolve into more energetic
white dwarf remnants, and will take longer to cool down. But here’s a critical concept: light is
radiated off into space as a function of surface area and the fourth power of temperature. The more they cool, the longer it takes to
drop one more degree. A carbon white dwarf of 0.6 Solar masses,
what our Sun will likely end as, would take a billion and a half years to cool down to
be merely as hot as our Sun’s current surface temperature. It would then take another billion and a half
to cool another thousand Kelvin, and the coldest white dwarf we’ve found thus far, a bit
under 4000 Kelvin, warmer than many red dwarfs, are over ten billion years old. So the white dwarf phase of our Sun, where
it is still giving off a significant amount of visible light, is going to last much longer
than its actual main sequence, as it slowly cools and shrinks its habitable zone and shifts
to a shade of white light more akin to incandescent bulbs or candles than what we think of as
vivid sunlight. This, incidentally, is not when it becomes
a black dwarf, a source of some confusion about the timelines involved as you’ll often
hear how it takes trillions of years. As mentioned, it takes longer and longer to
cool each increment, and in astronomical terms we don’t really care about visible light,
so Black Dwarf is a fairly ambiguous term, sometimes given as when it would cool to the
temperature of cosmic microwave background radiation, which is about 2.7 Kelvin and actually
gets lower all the time. So defining a black dwarf this way is a bit
of a moving goalpost, and which each progressive step takes longer and longer. Neutron stars, which are much hotter and far
denser, should take even longer to cool down. Whereas white dwarfs can only cool by photon
cooling from their surface, which stays a lot colder than their core, neutron stars
can cool by neutrino emission and so cool quite rapidly, initially. However they cool much more slowly than white
dwarfs over the long run, and may prove useful for maintaining a civilization long after
the stelliferous era. Let’s consider our Sun though or a parallel
one, once it has become a white dwarf and cooled to about our Sun’s temperature, around
ten billion years from now, and some billions of years after all the debris has been cleared
away or coalesced into planets again. Where’s the habitable zone? As mentioned this will constantly be contracting
but don’t overly focus on that. I mean, it’s constantly expanding right
now and civilizations shouldn’t just throw their hands up in despair because a billion
years from now they need to move their planet to avoid being frozen or scorched, considering
we generally rearrange our civilizations on timelines of decades or centuries, not billions
of years. It’s as hot as our Sun, but only Earth-sized
and extraordinarily dense, and it’s producing only about a ten-thousandth of its current
light, or 1% of 1%. Which means its Habitable Zone, going with
the Inverse Square of distance, is only a hundredth, 1%, of what it is now, about four
times further from this new-Earth sized Sun than the Moon is from Earth. Amusingly it is going to appear about the
same size and color in the sky of a planet orbiting at that distance as it does to Earth
now. There’s an issue with gravity in this scenario,
but we’ll get to that. I’d like to emphasize that right now the Sun
is slowly warming up and we’ll need to eventually move the Earth away to avoid baking it. We’ll have a problem during the red giant
phase where we’d need to move it quite far away for several hundred million years. But we will then be able to bring it back
in again toward the sun and slowly tap its orbital potential energy as it spirals inward
as it needs to be closer to the cooling white dwarf, over many billions of years. This post red-giant phase of Earth’s existence
will not be some brief last-gasp epoch of life, it’s one as long as what we’ve already
had. But it will not be quite the same though. For instance, the Sun will lose almost half
its mass during that red giant phase, and the orbital period at just .01 AU for half
a solar mass is only half a day. That’s a very short year, let alone day,
but don’t despair, you could set the planet’s rotational speed backwards so that the Sun
still rose every 24 hours, one of those tricks we discussed for Sun Moons around artificial
planets in Making Suns a couple months back. It takes some effort to spin a planet backwards
and keep it that way, but we’re already talking about moving planets at this point
and those are both child’s play compared to what we’ll get to momentarily. We’ll talk more about how to actually move
planets next week in Planet Ships. Another issue though is that while it’s
only planet sized, and reduced in mass, it’s not that much reduced in mass. If you’re orbiting it just 4 times further
away than the Moon is from Earth, about 1.5 million kilometers, that white dwarf of about
half the Sun’s mass is actually going to be exerting more force on the surface of that
planet than that planet’s gravity does, and indeed it won’t be able to exist as
a result, as that’s inside the Roche Limit. So we’ll need to consider some variations
on this plan to make the general idea workable. Now when the white dwarf is still warmer and
brighter, a planet farther out can do okay, and if it’s a little too cold it could be
warmed by mirrors concentrating the light. You could build a big lens at the Lagrange
point of the planet and its White Dwarf Sun and keep it nice and warm the whole time,
just expanding that lens as the star cooled. Additionally, you could cheat by building
a megaplanet too, which we’ve talked about before in the episode Mega Earths, and if
there’s one thing you’re not short of in an older Universe, it’s dense materials
like iron for building dense planetary cores. Several billion years is a lot of time for
gradual adaptation to higher gravity too, so you could get away with building some giant
iron ball far more massive than Earth as your new planet. There are also ways to counter stellar tidal
forces exerting crazy effects on our artificial planet’s topology, which we will discuss
another time. Unfortunately this all suggests that just
dropping Earth around a future white dwarf Sun is not a great option. Our more classic Dyson Swarm approach would
still work just fine, and using mirrors to concentrate light to warm those habitats is
less of a big deal, since the sunlight is already a bit unnatural looking in the first
place. See Environment of Space Habitats for details. However, if you built a big hollow sphere
around our own present-day Sun, out at the distance that would have normal Earth Gravity
on it, it would be 574 times wider than Earth’s diameter, with 330,000 times more surface
area. This sphere around a reduced white dwarf,
with half the Sun’s mass, would be 400 times wider than Earth’s diameter and 165,000 times
more spacious. You could essentially use that white dwarf
to provide your gravity to a massive shellworld, and help keep it warm, without needing to
worry about close-in tidal forces. Of course, providing light is a little trickier,
as we’ve discussed before. However, you would have a terrible gravity
issue if you tried to build a civilization directly on a cooled down, room temperature
white dwarf, which for the moment I will call a Grey Dwarf as I don’t think that term
has been used for anything outside Dungeons & Dragons. The temperature on a Grey Dwarf is perfect,
and it will stay that way for a very, very long time. But since it’s ultra-compressed degenerate
matter we’re talking about, not only do you need a protective shell between you it
and it, you’re also talking about a surface gravity of many thousands of times what Earth
has. Now, if you’re living on a shell around
a cooling white dwarf, you can keep contracting that as it cools toward this grey dwarf state
until you reach a point where the gravity is too much for normal life. An inorganic civilization, though, might be
able to handle a very high gravity, especially a purely digital one like those we focused
on in Black Hole Farming and Iron Stars. Such a Grey Dwarf civilization is no longer
biological and constrained to that specific room temperature environment, so they can
ride that grey dwarf as their heat engine all the way down to black dwarf status, quadrillions
of years later, taking advantage of the massive computational bonuses of an ultra-cold universe
as they do. Remember, the Universe is getting colder as
time goes on as well, and as long as something is warmer than the environment around it,
it can be used to generate power. By the Landauer limit on classic computation,
the processing power per joule of energy used is inversely proportional to temperature. So these artificial beings will enjoy a very
long and prosperous existence on that Grey Dwarf. Similarly we probably shouldn’t rule out
the option of turning the degenerate star into an actual computer, some hypothetical
computronium, which has been suggested as an option for neutron stars, such as the Hades
Matrix in Alastair Reynolds’ novel “Revelation Space”. The big advantage of this, if you can pull
it off, is that it’s literally the densest computer with the minimum signal lag between
components that you can make, only slightly less dense than a black hole. For that matter, Robert L. Forward’s classic
novel “Dragon’s Egg” actually has life evolving on a neutron star, with neutron starquakes
endangering civilization. For these beings time proceeds very rapidly
as as they exist on the microscopic scale. Improbable, but an interesting approach to
alternative chemistries for life, and we might be able to do strange things like entangle
entire stars to create oversize quantum computers too, one day. It is worth noting though that all that lost
mass during the red giant phase is mostly unused hydrogen, and you could take most of
that and make a very nice new sun: a fully convective red dwarf with a multi-trillion
year life, that closely orbited that white dwarf as a binary. That’s one possible way of doing urban renewal
on a recently dead star system ending its red giant phase, by sweeping up all that excess
hydrogen to make a binary partner for the white dwarf. Indeed, this is how we get one of our major
types of supernovae, Type 1a. When a bunch of hydrogen accumulates on a
white dwarf, usually robbed from a close binary sibling, it will erupt as a giant explosion. I should also note here that there is such
a thing as a regular old nova, the smaller cousin of the better known supernova, and
they’re very common but don’t get much attention these days. Same basic process, just milder. A little bit of matter leaks onto a white
dwarf, fuses, and releases a modest explosion. We get about 50 of these a year in the Milky
Way. But as long as you’re doing it carefully,
you can keep feeding a little more matter to a white dwarf, in a stable process of fusion. I dislike this approach compared to the normal
star lifetime extension method we discuss here, starlifting out heavy elements and adding
more fresh hydrogen as needed. But it is one way to rekindle a star that’s
already dead, and since the light produced is soft x-rays, not something we’d want
to get a tan with, it works well with an external shellworld approach where it’s just being
used for power, not direct sunlight. Of course we’re not necessarily uninterested
in making things blow up. The problem with almost every stellar engine
we discuss here is they only produce a lot of power in a relative sense. A star is immensely more powerful than our
own mundane power sources, but it’s still a trickle supply, taking billions of years
to go through its fuel. Sometimes you might want a lot of energy very
fast. We have previously discussed megastructures
that make even a Dyson Swarm look tiny, like the Birch Planet from Mega Earths or the compressed
galaxy, which is a swarm of stars like a giant Dyson swarm that we envisioned at the end
of the episode Making Suns. But when we talk about moving stars via Shkadov
Thrusters, or even whole galaxies, we’re talking about a dreadfully slow process because as
powerful as those stars are, they are also ultra-massive. So sometimes we might want to go the larger
Nova route of white dwarfs, or even the type 1a Supernova route to get vast amounts of
energy quickly, if for instance we wanted to move a star faster. For that matter, this trick works on neutron
stars too, which we haven’t mentioned a use for yet. When a Supernova explodes, the energy output
tends to parallel what a star like our own will release during its whole multi-billion
year life. It might seem like far too much energy to
ever want to capture at once, but maybe it’s not. We often talk about fusion, a technology that
often gets labeled as the energy source of the future, and always will be. But actually we’ve been able to do fusion
for a long time, people just aren’t too keen on detonating hydrogen bombs in massive
underground vats of molten salt. We’ve also discussed using pulsed nukes
to drive ships, as in the Orion or Daedalus projects. A supernova is just a pulsed fusion reactor
on a grand scale. And they do not release all their energy in
a single instant, and they range in power, generally about 10^44 Joules, peak luminosity
is usually around 10^38 watts, a bit under a trillion times that of our Sun. So a classic dyson shell running on something
like that would need to be about a million AU, about 16 light years, in radius. It sounds really big, BUT, we can produce
much smaller novae, and more to the point, if you’re constantly detonating them in
the same place, you are going to have a lot of gas kicking around absorbing light and
slowly releasing it. So you could go a lot smaller, and note that
is one alternative to building something even bigger than a Birch Planet. Those are limited in size by how big you could
make one with Earth-like gravity on the surface without being inside a black hole. However, what people can survive and what
a big metallic shell or plate can survive are very different things. Besides being able to take a much stronger
blast at once and in wavelengths that are harmful to us, a typical piece of metal with
a very high melting point, like Tungsten, can handle thousands of times the constant
radiant power compared to a human or plant on a planetary surface. So a very, very large metal dish or pusher
plate, about 4 or 5000 AU out from the event, about a light month, should be able to withstand
regular blasts of a supernova. Needless to say this distance could be reduced
with smaller explosions or with stronger materials. If you were detonating a typical supernova
about once a week, you now have a massive engine producing many billions if not a trillion
times the power of our own Sun. This is by definition a Kardashev-3 Engine,
not the usual Kardashev-2 stellar engines we normally discuss here. You can use it to power an entire galactic
civilization or to move an entire galaxy. So far, we’ve mostly been talking about the
natural end of the universe, if our present understanding of things is correct. But it won’t really end that way. We talk about how the Stellar phase of the
Universe is just starting and we’re not even 1% of the way through the primary star-forming
phase of our galaxy, but in truth, we’re probably in the last 1% of it right now. We can never speak with certainty about mankind’s
future in space as there are just too many unknowns. But if we follow the general assumptions about
colonization we’ve been discussing on the channel over the years, we can make a very
educated guess. In the next few centuries we’ll start launching
colony ships, not a few, but millions of them, huge interstellar arks that will race outward
at a decent fraction of light speed to settle every star system in this galaxy and keep
going till they bump into someone that says, “Stop, these places are ours”, be that
in our own galaxy or out at the edge of our supercluster, billions of years from now. As the Universe ages there will be more and
more worlds with the potential for life and more and more time for them to kindle their
own native civilizations. Odds are, though, we won’t meet any in this
galaxy, because if they were here we’d have encountered their colonists already, since
at our current rate of technological progress we’ll fill the galaxy in a blink of the eye,
and we’d expect they would have too if they’d shown up first. So we’re likely the first. Our descendents will not stop at merely terraforming
a few Earth-like worlds around friendly suns, they’ll colonize everything, possibly demolishing
whole suns by starlifting to make either tailormade stars or merely as feedstock for alternative
habitats, organic or digital. Even if they don’t tinker much with existing
Suns, they’re unlikely to let new ones form if they’re not as efficient as what they
can cobble together. In this regard, all the stars of this galaxy
are an endangered species, Dying Stars who count their lifetimes in mere millions of
years, waiting for us to arrive and repurpose them. Most will probably be destined to either end
as the center of a classic Dyson Swarm or as the furnace in the basement of some mega-civilization,
or simply disassembled, torn down to a small convective red dwarf or just basic build material. If you have controlled fusion, or can build
kugelblitz black holes, or cheaply transmute elements or efficiently make antimatter, why
bother using stars at all? You’re still constrained by thermodynamics
which puts limitations on how close you can mash a civilization together and effectively
radiate waste heat, so that it resembles a Dyson Swarm, but that doesn’t mean you have
to use a big, clumsy and unwieldy natural star if you’ve got better options. Efficiency will matter to them since every
bit of wasted energy is someone’s life if you’re trying to stretch civilization out
as big as it can go and for as long as it can go. Every star not contained and every galaxy
allowed to drift away are potential civilizations that could have been. After the next million or so years of rapid
galactic expansion, we’re likely to see a period where folks begin shepherding their
resources so they can keep going and prospering long after the natural stars of this universe
have burned out. In fact, that last natural star burning out
might find itself the toast of the party, like at Restaurant at the End of the Universe,
but not a going away party, rather a tribute to the dawn of new civilization, more prosperous
than before, filled with artificial environments or simulated worlds based in ultra-cold computation. It’s possible that the last star might not
be seen for many trillions of years, or it may be just a few million years ahead of us. As we go about moving stars, or extinguishing
them and moving their disassembled components into closer, more useful configurations for
a future galactic mega-civilization, potentially composed of quintillions of simulated worlds
and universes, I could see us making a big show of putting out that last star. A big celebration, a Restaurant at the End
of the Universe for those last physical engineers working in the remnants of this old Universe,
as we shuffle off to new ones of our own creation, leaving the ebbing light of those last dying
stars of a dark and expanding Universe. As mentioned, a lot of the topics we covered
quickly today are covered in other episodes on the channel, but we’ve never really discussed
the full life cycles of stars that much and even today we mostly focused on the implications
of their old age to future civilizations. If you’d like to learn more about the lifecycles
of the stars, then try out “Seven Ages of Starlight”, a great documentary about the
life and evolution of stars available on Curiosity Stream, one of many excellent astronomy videos
they have. Curiosity Stream is a subscription streaming
service that offers over 2000 documentaries and nonfiction titles from some of the world’s
best filmmakers, including exclusive originals. You can get unlimited access starting at just
$2.99 a month, and for our audience, the first 30-days are completely free if you sign up
at curiositystream.com/isaacarthur during the sign-up process. Next week we’ll be discussing how to move
entire planets and even how to use them as a massive interstellar spaceships, or possibly
even intergalactic ones, to colonize galaxies far outside our local group of galaxies. Lastly, we’ll close out the month with our
monthly Livestream and Q&A, which will be on Sunday, March 31st, at 4 PM Eastern time. 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!

36 thoughts on “Civilizations at the End of Time: Dying Stars

  1. But what about those Exotic matter stars?
    Like neutron stars, quark/gluon stars…
    I heard that they observed something that even looks like Neutronium star?

  2. The topics you discuss are on titanic scales yet you explain them in an approachable and descriptive way. It’s really phenomenal what you are doing. Just putting these videos out and having these ideas spread will maybe inspire and empower individuals to get us the a place where we can colonize our galaxy.

    There is tremendous weight to what you are doing here and I believe it won’t go unnoticed.

  3. In the big rip theory, the force of dark energy isn't constant and increases over time. This causes first galaxies to fly apart, then solar systems, then planets, then stars, then atoms, then the atom nuclei. If it keeps increasing, it would start pulling the quarks inside protons and neutrons from each other. Since quarks have to be in pairs, if enough energy is put into pulling the quarks apart, they will just create new pairs. If this is true, wouldn't this cause a runaway effect of quarks "duplicating" until it supersedes the expansion of the universe?

  4. Here's a fresh suggestion for an alternative future hideaway for life — interdimensional habitats.

    There's good reason to believe that our 3+1-dimensional universe exists within a grander structure of more and/or other dimensions.

    If we could learn to traverse out of one or more of our four familiar dimensions and into, through, or between other dimensions, then our civilization might find a place to exist comfortably virtually forever.

  5. There is much less dark matter than currently assumed. Reason: Expansion of the universe is not considered on small scales (small scale = galactic scale). This acts like "weakened" gravity. Expansion of the universe does not explain everything that is currently explained by dark matter. But there is no magical stuff sitting in the halo sitting in the halo of very galaxy. Mass hypnosis. It doesn't even make sense: Magnitude of dark energy and vacuum energy doesn't fit, which is caused by the amount of dark matter currently assumed in existence. Why is there no dark matter in the solar system. And so on.

  6. Something something boltzman brains as an argument against the heat death of the universe something something.

    I read somewhere we are like a soap bubble in some fancy higher physics, a bubble emerging from something more vast, something something physical constants differing as one approaches different regions across the bubble.

  7. ok if this is all true then it makes our universe an even lonelier place that we already thought. Suppose we could remake our own milky way in a few million years our so that means that any other intelligent civilisation could have done this as well. But if we look around us we only see natural 'dull' galaxies. So or our far future cousins are far less industrious then we imagine them or we are alone in a sphere of say 1 to 2 billion lightyears or perhaps we are all evolving together right now and have a nice party in a few million years or so…
    I think of those three scenario's the last one is the least likely and the second one is the most likely. Of course we still have the big filter of Nick Bostrom that might be waiting for us in the near future…

  8. Life/humans evolve on a much shorter amount of time than the sun's billion-year change of 10% in temperature. Maybe we won't need to move the earth as much because, biologically, life could adapt in that billion years?

  9. Isaac Arthur I have a question. What if light is the only the "fasted" thing we can measure? What if something is travelling faster than light but since it doesn't interact with any thing we can't see it and obviously measure it? And just because we can't see, measure or speculate on it, currently, doesn't mean we shouldn't. Is their any math that could prove such a force exists?

  10. Hey on the subject of the end of time at least for humans. The fact that the andromeda galaxy is moving towards us is unusual. Who thinks this could be by design of sum alien intelligence collecting up mass for its civilization? Sum sort of galactic land grab situation collecting as much mass as it can to hold on for use during the heat death era. You think theyd just go full 40k and exterminate us?

  11. What an unbelievable gem in the steaming, YouTube heap. Isaac ought to be on prime-time instead of the useless talking-heads (lower case because the band is keen).

  12. About Grey Dwarves: While gravity around them might be high, building a ring around them in orbit is possible. Slowing said ring down to give you about 1 g seems like a possible thing to do, allowing biological life on/around the dwarf.

  13. I have a feeling no matter how advanced, humanity will maintain the Earth and the Sun for as long as possible.

  14. I wish you'd write sci-fi. The concepts ventured here are so much more advanced than those found in most sci fi with some exceptions like Ringworld. But even a ringworld is boring by this channel's standards

  15. 32:00 sounds like humanity actually is just a fortunate virus, consuming down to the last proton for our own propagation and nothing else.

  16. What if our Big Bang was actually an artificial supernova created by a precursor omega-civilization that attempted to reboot the universe?

  17. Love the channel Issac.
    Build ships..check.
    Start harvesting icy astroids and comet's…check.
    Separate into hydrogen and oxygen..check.
    Build small fusion reactors..check.
    Drifting through dark space as small Islands of humanity collecting hydrogen for fusion fuel for eternity..uh..yep..check.

  18. its unlikley that we will move a planet. so we will have to leave during the red giant phase.
    but will we go to titan? io? mars will still be a vaccous ball of rock. though maybe wetter.. as it cools though the water will slip into deeper cracks..

  19. i have never got a good answer as to weather our planet will be consumed by the red giant sun. i think it survives, but not in very good shape. so it will probabily loose its atmosphere. thus we will need an armatta to live in. if we are still biological, it might be the moon. there are places in the moon which should maintain a shirtsleeve temperature. so we just need a shell there, deep inside.. we have fifteen lbs of air above to protec us from thenradiation of space.. so we would need about 18 feet of wet natural gravel between us and space. thats not too deep. as for the endgame of earth i thinkmwe have a lot more planning to consider. but it depemds on the habitible zones.. remember lunar pols are very cold.. but the equater is very hot.. so we should be able to find a place on earth that fits our confort zone.. will we just tunnel into the hills of greenland? extracting oxygen from solar arrays out in the toxic co2 air? (were not going to stop producing carbon are we?). no we will just start scrubbing.
    maybe earth toll get too hot and we will just pick some icey rock out near jupiter.

  20. artificial bodies i think are the way to go, you can survive much more environments… though i think it'll be dreadfully boring

  21. You weren't being totally forthcoming in saying big stars are the only ones to nova. You failed to mention the list of reoccurring micro nova's from smaller stars. The list was available at the time this video was made.

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