Galactic Civilization’s End

civilization last? And notice that I just used the word civilization and technological not necessarily human civilization, since time and space scales the kind we're talking about could really blur the lines of what it means for a civilization to be human or consistently any one biological species. So for now, I'd say, let's just define civilization as something like a

continue this tradition of intelligent behavior. Uh, if you've got something like that, Assume a civilization like ours leaves Earth and spreads out to colonize other star systems and becomes a presence on the galactic stage. How long could a civilization like that actually survive into the future. You kind of have to think of of civilization as a virus spreading through this uh, this galactic and ultimately I as a universal host. How how far could it spread? How

long could it maintain the infection? Um? And it's it is challenging at times just to think about it because we we can't help but extrapolate what we have now and what we know, and we have to do that in order to to sort of scale up the model of what a galactic civilization might look like. Um. And at the because I think back to Star Trek for instance. You know, Star Trek is essentially a show about clipper ships.

It's about seafaring individuals. It's just extrapolated into space and then uh, you know, with a lot of cool science science and science fictional elements explored within it, exploring the planets of potted plants. Yeah. But but ultimately it is it is based on the model of the president in the past. Um. And then then there's also this this element too of just um you know, uh, grandiose pride and human accomplishment to to wonder where will we be uh in this distant age. It reminds me of of

a quote from J. M. Coats. He's waiting for the barbarians, and which he writes, quote one thought alone preoccupies the submerged mind of empire, how not to end, how not to die, how to prolong its era. I think that's quite true, though, I mean the conception of empire that we have is so time limited. I mean people who are trying to prolong the empires that were used to thinking about, say Cotsy probably has in mind something like

the British Empire um. That is an empire that, even though it existed for a long period of time, was on the scale of you know, people's recognizable descendants. You know, you would be saying, I want to hand on my empire to my child, or my grandchild or my great grandchild. Do you do you want to hand on your empire to something that is maybe not even recognizably the same species as you a million years down the road. Yeah.

It kind of becomes the situation where one is, say passing on a typewriter or or some other piece of technology, where you're like, this has been in our family for years, and then you're like, well, thanks, but it's and it is now obsolete. It is it is kind of useless. It's it's actually of more value perhaps now as a mere museum piece or just as a metal to be recycled.

That's true, I guess it. Also it sort of works out how you don't have to care about that thing that's a million years down the road, whether or not you think of that as your direct descendant or not, because you care about next generation, and that generation will always care about the next generation. It's just an echo

through through time and space. Yeah. I think one of the important things to deep in mind and all of this is just to what extent to things UH scale up, you know, because we think about the empires and the technology we have today and UH, I think is what As we proceed through this discussion, it will be reminded time and time again that that that human life, human empires, they don't really scale up when you start applying them to even even at the interplanetary stage, things begin to

get a little difficult. But certainly when you get beyond beyond that, when you talk about UH, an empire that spans solar systems or or or manages to spread throughout an entire galaxy and human life as well, there are challenges. Obviously, there are challenges when we think of of what we have now, and even if you achieve some sort of biological or digital immortality, um, it's it's difficult to put

that in context. Yeah. Now, one of the first questions that you might ask is, well, how long would it take? How long is it gonna take for a galactic civilization to emerge? Okay, we gotta get there before we can ask how long it will exist or survive? Right, Yeah, And this is something that science fiction and authors often kind of hatch you out, depending on how into you know defining a timeline they are. Now. In his book Cosmos,

Carl Sagan commented on the Drake equation. Right. So, the Drake equation we we've talked about on the show before, but if you'll recall, it's essentially an equation put together to come up with a rough estimate based on some some variables where you can plug in your assumptions for the answers UH to figure out how many technological civilizations

you would expect to find in a galaxy. So basically, the short version is you take the number of planets that there could be life on and then multiply that by some probabilities like the fraction of planets where life emerges, the fraction of the is where intelligent life evolves, the fraction that's capable of interstellar communication, and the years a civilization tends to remain detectable before for whatever reason, uh

disappearing right. And Sagan pointed out that civilizations might tend to destroy themselves soon after reaching the technological phase, but that at least some civilizations might learn to live with high technology. He figured that, using the Drake equation, if just one percent of all emergent technological civilization survived this

technological adolescence, then there could be millions of civilizations out there. Now, there don't appear to be millions of civilizations out there well as far as we know, as far as we know. But but here's the thing. Sagan and William Newman calculated that if a mill that if a million years ago a space faring civilization emerged two hundred light years away from us and spread outward, survey ships would only just now be entering our solar system. And then what would

that even look like? What would a million year old civilization uh, you know manifest as uh? I mean, our current and only model outside of sci fi dreams is our civilization. It's me. And it's a mere you know, tens of thousands of years old, and we've only been a technological civilization for a few centuries. So what would these presumed immortals even be interested in when it comes to exploring and colonizing new worlds? Would they have would

would they be interested in that at all? Would they sort of would they perhaps give up on their colonization efforts, uh after they realize that they need to perhaps extend their their energy and other directions. It's a good question. I mean, I think that it helps, um it helps when trying to imagine the future behavior of civilizations, whether alien or ours, to try to have as few assumptions

baked in as possible. And so you can make assumptions maybe about what alien psychology might be, like, what their their directives are an exploration, but all of those are somewhat fallible. One of the things I think we can bank on as an assumption about future your civilizations is that they will need energy. That that's that's a that's a kind of ground level assumption that just you can count on that. But then how how might their goals change?

Like they have energy, they could have all the energy, certainly in a world, in a solar system, in across multiple systems. But then what do they really want to do with it? And and indeed do they want to survive the long term challenges of life in our universe with their goals understanding? And even experience of time and space differ from what we humans value and experience today. Uh, it could be, but once you get into those scenarios, it's just hard to it's hard to predict anything with

any confidence. Yeah, I mean so, yeah, this is where you get into the really the domain of science fiction. Um, I don't Oh, and there's plenty of great science fiction along these lines. Yeah. I'm reminded of the various advanced Elder civilizations in Ian Ebanks culture books. Um, because beyond the the high level involved civilizations that engage with other galactic civilizations in these books, there are what's known as

the sublime. The sublime these are advanced civilizations that basically, at some point they just left all of their their works behind because they've left the known dimensions of space time behind to take up residents in several higher dimensions higher dimensions. Now, does this what assumes string theory or something like that, in which they're they're tiny higher dimensions where you can somehow bacond your consciousness into some kind

of substrate that can transcend into those hidden dimensions. Well, that's where my mind goes to, especially since we've we've very recently spoken about dimensions and string theory. Uh. Now I haven't I haven't read some of at least one of the key books that deals with the sublime in

the culture A series. But it's basically the idea that that suddenly that this particular group has reached a level of technological and cultural advancement where they're not even playing the same game as we are, that they are perhaps not even really experiencing the universe in the same way as we are, and they just kind of leave it behind. Uh indeed, like a like like like something emerging from a chrysalis and uh in taking off into a new

realm of being. And but in doing this, at the same time, it's possible that sublimation uh might actually protect them from the truly long term environmental risks of living in our universe. So maybe it accomplishes the same go But of course that is that is the benefit afforded by playing in the realm of imagination. We don't know if anything like that is possible or not. So let's get into some of the long term environmental challenges of of life in a hostile universe. Well, I guess first

we should look just the planetary level. Yeah, let's start with with Earth itself, right, So there are a number of factors to consider here, the most obvious being threats from within and threats from beyond. So we certainly have the ability to drastically damage the life sustaining properties of planet Earth. In fact, we are we are currently doing that. Yes, yes, with with say greenhouse gas emissions leading to global climate change, we are verely hampering the Earth's ability to sustain a

civilization like ours far into the future. Yeah, the results can be catastrophic. Now, could we actually wipe out all life on the planet if such an evil aim possessed us? I think we would probably have a hard time doing that. I mean, life is pretty resilient, but we could come frighteningly close. I've seen some estimates for how a large enough nuclear war uh could could severely damage and wipe out, you know, a significant number of of life forms on

our planet. I also read get this, um how even even an extremely powerful detonation in the Mariana Trench could collapse the food chain and wipe out most plant and animal life specifically. And this is according to uh x k c D s Randall Monroe uh x k c d as a science blog and comic series online. Uh He, according to his calculations, a fifty three million in megatun explosion down in the trench might just do the trick.

This would be equal to the chicks Aloop impact that occurred roughly sixty six million years ago, which led to the Cretaceous Paleogene extinction event, and that killed sev of all animal and plant species. That was the size of a city, and it had the power of a billion nuclear bombs. And this brings us to the extinction events

that can occur due to unchecked space collisions. Yeah, now there's there's actually been some evidence to support the idea that there's a a twenty six million year cycle linking comet showers and global die offs. Yeah, there are people who pause it all kinds of like like periods of space impacts and what the causes of those might be. But one thing we can say is that space impacts are just a statistics game. I mean, you're it's just

a waiting game. Like you know, every so many years, you're you're pretty much statistically guaranteed to get X number of powerful storms that hit a certain part of the world. Space impacts are the same way. There are a bunch of objects out there, they're flying around, and you can just calculate it out over certain periods of time, statistically you're going to be hit by X number of objects

above a certain mass. So when you're we're talking about a human civilization, uh, surviving however many you know, thousands upon thousands upon thousands of years, certainly reaching like the million or two million. Your point. If you want life to continue on Earth, then you have to do something about the potential impacts. Because defense, Yeah, you gotta have planetary defense, which is something that uh that people are working on. Uh we've discussed it on the show before.

It's still not as much of a priority as it should be. You have all of these uh, these politicians out there, you know, making campaign promises and talking about what they're gonna do for for for to improve everyone's life, and it always floors me that this is not something that people take up because this is one of the This is perhaps the only, or at least one of the very few causes where we can say this is something we can do to save the world. This is

something we can do to protect the planet. Yeah, what what if there? That was like a what if that was a campaign platform? It was basically civilization level defense. So your your campaign platform is fight climate change, protect the planet from space object impacts, and let's say the other big one would be prepared for the next superflu It makes sense to me, I mean, I guess the the the the counter argument here is that most these

are these are generally longer term threats. Uh, so people are going to be less inclined to let it impact their voting behavior. It's frustrating. But anyway, uh some other problems that, of course so be as we've discussed before.

Venus offers an example of this of a sort of worst case runaway greenhouse effect that could leave a planet, even a planet like Earth, uninhabitable, And there are also various long term scenarios involving the world's oceans, the magnetosphere, which if you listen to the show, you know that the magnetosphere plays a vital role in protecting our planet from silver and cosmic radiation, and if something were to happen to that, then we're unprotected. There are also biological

threats from within Earth's biosphere. That's right. You have to consider the likes of Peter Ward's media hYP hypothesis. I was actually not familiar with this. This is a kind of an opposite of the Gaia hypothesis and uh, the Medeia hypothesis is that multicellular life is a suicidal superorganism

leading to microbial triggered mass extinctions. I mean, whether you buy the framing is a suicidal superorganism, it is clear that there have been times in the past where life on Earth caused massive extinctions of other types of life

on Earth. I mean, we think about the oxygenation of our atmosphere that we are now adapted to was initially tragedy that killed killed off tons of life, and then of course we've seen this this particular primate species rise up and uh and and alter the atmosphere from a very early time. And then of course there are the outside context problems to consider, which, of course is a term that was coined by Ian M. Banks but has been used since then by various other authors and even scientists.

You call them outside context problems to consider, but sort of the nature of them means that what you can't consider the right right. Yeah. Banks said that an outside context problem is the sort of thing most civilizations encounter just once, in which they tend to encounter rather in the same way as sentence encounters a full stop. Um.

So yeah, if we could. The classic example, of course is um, if you have a primitive terrestrial society and then uh, a colonial force shows up with advanced technology, you know, and then to extrapolate that into space, an alien civilization shows up with it with advanced head ology. But of course, when the thing about the the alien consideration is that a lot of very intelligent folks have

thought about this problem. There are even some rudimentary plans in place to deal with it when it occurs, you know, people who think about first contact. So it's not really a completely outside contact problem. Yeah. You could look at a lot of science fiction as us doing our very best to use our imaginations to prepare for this potential conflict. Right. But one of the big hard limits for life on Earth uh and in our solar system itself, concerns the

life cycle of our son. Now maybe we should take a quick break and then come back to UH to discuss and weep in anguish over the death of the Sun. Than alright, we're back. So we we've talked about the life cycle of the Sun before on this show, but just to refresh, this is basically how it it works. So our son has been going strong for four point five billion years and it has another five billion years

left in the town. When the courts roughly speaking, roughly speaking, now, when the core runs out of hydrogen fuel, it's going to contract under the weight of gravity. Some hydrogen fusion will occur in the upper layers at this point. But as a depleted core contracts, it heats up, and this heats the upper layers of the Sun, causing them to expand. And as the outer layers expand, the radius of the Sun will increase and it will become a red giant.

And the radius of the of a red giant son, our red giant son would be a hundred times what it is now. It's not good. Now, that's that's not good for anybody, because this would this would put the put the the the the outside of the Sun just beyond the Earth's orbit, and some scientists have estimated that this would just vaporize our planet, but there's also a good chance it would push Earth and its moon outward

after consuming mercury and venus. In any case, whatever it does, it does not sound like a survivable event for the inhabitants of Earth. That's right, It's just it's it's bad news. And long before this happens, say in a mirror one to two billion years, the Earth is gonna go hot enough to to boil away its oceans as well. And if we're looking really long term, um, here's how it'll it'll all play out. According to Ethan Seagull, who wrote how our Solar System will end in the Far Future

for Forbes. Uh. He says that in nine point five billion years, the sunile collapse into a white dwarf, and the remaining dead worlds will continue to orbit it, and eventually the white dwarf will go dark in the inevitable collision between it and another black dwarf will blast apart the remnants of our solar system. So all that and the Sun doesn't even get to turn into a black hole. That's right, the Sun will never get to turn into a black it's not massive enough. Uh, and yet it

will wreak havoc. Nonetheless, So what's our fight or flight response here? Well, it obviously means if our civilization is going to survive into the realm of say billions of years, if you're on the billions order of magnitude for the future, we can't stay here, that's right. We've got to build ships, We've got to build colonies. We've got to estab colonies

on other worlds and other systems as well. Or perhaps we do something to just move the Earth itself, because as we ascend the Kardashian scale, such things do theoretically

become possible. Sure, at least in theory. For instance, we can harness comments and asteroids so they gravitationally slingshot past Earth and move us into a wider orbit away from the Sun. We could build planetary sunshades that have the same effect, or or very or even just sort of turn the Earth into a spaceship of sorts, you know, just take it with us. Well, there are versions, like, for example, there is one idea that's not for moving

planets so much as it is for moving stars. But I wonder if similar principles could be applied to planets, where it's known as the Scatoff thruster if you're read about the Yeah, so this is for stars. But what it would do would be would be sort of a large reflective encasement for part of a star that would cause a positive radi asian pressure in one direction back against the star. And by reflecting all of this radiation back in the direction of the star, you could actually

steer the movement of a star. One wonders if you could create some kind of similar solar sale like thing for a planet. Then again, the planet is not emitting radiation the way a star is, So I don't know, maybe maybe possible, maybe not, Yeah, or ultimately we could just leave it behind, move on to better worlds, make better worlds. Exodus from an uninhabitable Earth has been a sci fi staple for decades, going back at least to

the nineteen thirties. That's when British sci fi author Olaf Stapleton wrote about it and uh during the events of Frank Herbert's Dune, Old Earth is said to be an uninhabited waste. Oh yeah, do they ever go there? I don't not. In the the original books that they might have something that takes place in the more recent Dune franchise books, but I have not read them, so I would love to hear from from hardcore Dune readers on that. Now. When it comes to moving the planet, though, we also

see some work there in science fiction. Sci fi writer Stanley Schmidt explored it in nineteen and Ian M. Banks also wrote about it. So we're kind of climbing a Kardashian scale of destruction here. So planetary power and the ability to save one's planet in some sense, then solar system power and the ability to save oneself or roll with the changes to a single star system. But what about beyond that? What about the fate of galaxies in the universe itself. Yeah, yeah, that's a good question. I

guess that's where we have to go next. Now, before we do that, we should pause for the reality check and and not ignore the much much nearer, more salient threats facing our species right now. We mentioned some of those earlier, primarily things like climate change in all of its myriad downstream effects, killer pandemics like the next super flu, the threat of space impacts, nuclear war. Maybe some people

would throw artificial intelligence in there. I don't know. That's that seems like a much bigger question mark to me. But I think the big ones we really know to be concerned about, based on the most solid science, would be things like climate change in pandemics. We know those are real threats right now. We have to be fighting and preparing today if we want to thrive in the future. Uh. And of course we've discussed those in the past and we will revisit them in the future. But to continue

today's thought experiment, let's let's go that next step. So we imagine our technological behaviors can be changed, and we beat back global climate change, we survive all these other threats in the near term, We expand our space exploration and colonization ability. We spread out our civilization so that no one local event in any individual solar system can

bring it to an end. When do much bigger concerns like the space, time, and energy dynamics of the larger universe start to actually become a threat to our survival, Well, not anytime soon, right, but but as far as we know, as far as we know, but there are predictions for how it might go down. The sort of universal apocalypse. In fact, they're there at least four main models here. We're gonna start with the two older models. One is the Big Freeze. Uh. And this has to do with

just an eternally expanding universe. Uh. And we know the universe is expanding. Uh. So the idea here is that everything expands to the point where there's just heat death across the universe, the triumph of entropy in your life with just a cold, dead universe. According to some of the models. One thing that can often be misleading about the idea of the heat death of the universe is that if you if you're not familiar with this term, it sounds like that might be hot. It's not hot.

It's the opposite. It means it means usable energy gets converted into heat, which is entropy energy you can't use, and everything is just this cold bath of slightly above absolute zero radiation. Now, the the other side of that, of course, is the idea that what if things expand to the point and then they retract uh in a collapsing mechanism. This was this would lead to what is

considered the big crunch. So the universe stops expanding, crunches back down over time into the reverse of the Big Bang. That doesn't sound good for you know, but yeah, but this would be this would be a hot death as a cold as opposed to a cold death. Now, back in nineteen seventy nine, physicist Freeman Dyson. Dyson is still with us as of this recording. He was born in But he pondered just how these two possibilities would impact humanity or whatever humanity becomes over the course of time,

and he was he was pretty optimistic. Yeah, we should know that this paper we're gonna be talking about is fantastically readable. But Dyson was working with the knowledge available to him at the time in nineteen seventy nine. So, for example, this predates the discoveries that seemed to indicate that the expansion of the universe is accelerating. Dyson didn't

know that at the time. At the time, he vote, quote, the prevailing view holds the future of open and closed universe versus this being the idea that to a closed universe is one that will eventually collapse into the Big crunch, and an open universe is one that will just continue to expand towards this big freeze. He said, uh uh, quote the future of open and closed universe is to be equally dismal. According to this view, we have only the choice of being fried in a closed universe or

frozen in an open one. And he can He goes on regrettably, I have to concur with es verdict that in the case, in this case, we have no escape from frying. No matter how deep we burrow into the earth to shield ourselves from the ever increasing fury of the blue shifted background radiation, we can only postpone by a few million years. Are miserable? End? Oh wow, I

was just thinking. So the blue shifting of radiation means that if radiation sources are accelerating towards you, the radiation they emit gets uped in frequency, gets blue shifted up higher. So does that mean like radio waves, the cosmic microwave background radiation and all that as it closes in towards you gets blue shifted up and turned into gamma rays. I get something like that. That's that's That's what I'm

getting from this. But this is with the closed universe model, right, and and he he largely avoids the quote unquote claustrophobic nature of the closed universe in this paper, but he

does offer this. Uh, this idea, he says, supposing that we discover the universe to be naturally closed and doomed to collapse, is it conceivable that by intelligent intervention converting matter into radiation and causing energy to flow purposefully on a cosmic scale, we could break open a closed universe and change the topology of space time so that only a part of it would collapse, in another part of

it would expand forever. Uh. Yeah, I would call that optimistic. Yeah, but I mean he's he's basically throwing it out here and saying, look, I'm not sure how this would work exactly, but if we're talking about a significantly advanced civilization, this sounds like the kind of thing such a civilization would be into doing and maybe maybe have the ability to do it. Yeah. Uh. One thing I like about Dyson's attitude here is that he he's essentially saying, you know, physicists,

you should explore extreme implications. Uh. He starts off his paper by talking about Stephen Weinberg, the Stephen Weinberg quote that the problem with physicists is not that they take their theories too seriously, but that they don't take them seriously enough. You know that they scoff at some of the discussing some of the more outlandish implications of theories that we know to be good theories and are confirmed by evidence. Uh, and Dyson's like, no, let's get into

the weirdness. Okay, we've got a theory. We think it's a good theory because it predicts all the stuff we see. What does it imply? What are the weirdest things that implies? Again, this paper is uh is really readable, very accessible, especially for a paper that has so many equations in it. But but he also has some some very helpful timetable

scale els. For instance, he has his table one summary of time scales, and he he holds it in a closed universe, you'd have a total duration for the universe of ten to the eleventh power years or a hundred billion years. And and then when he looks at the open universe, he basically takes it by by order of magnitude.

So he taught this is what he says, quote, it takes about ten to the six or one million years to evolve a new species tend to the seventh power, or ten million years to evolve a genus tend to the eighth power or a hundred million years to evolve a class ten to the ninth power, or one billion years to evolve a phylum in less than ten to the tenth power years, or ten billion years to evolve all the way from the primeval slime to Homo sapience.

I'm not sure if his taxonomic organization of of time scales of evolution is exactly right, but I mean he's working essentially with orders of magnetzya. He's definitely rounding up.

He's so, for example, he says, you know, less than ten billion years, I guess that's actually that's a fair number to work with if you're just trying to estimate galactic evolution, right, because you're ultimately trying You're you're dealing with with life and life on Earth, which is just a pin drop in the in in terms of cosmic history.

But you're you're, so you have to work with these exceedingly large orders of magnitude, right, But but playing with rough orders of magnitude gives you more, essentially more room to play around. So life on Earth has not been around for ten billion years, but it's been around for more than one billion years, So you can essentially just round up or down to the nearest order of magnitude. Now ultimately for an open universe scenario. He does say

that he does think it's pretty hopeful. He says, quote, so far as we can imagine into the future, things continue to happen in the open cosmology, history has no heir and his in this paper. His basic breakdown in this paper is that consciousness is not bound to biology of it is structural. Then we can move beyond the body. We can become digital machines, we can become uh, you know, black clouds of particles. That intelligence doesn't necessarily have to

be confined to flesh beings anymore. And he had There's also an interesting point in this where he talks about immortal computing, which I hadn't really thought about. He says, quote, a society with finite material resources can never build a digital memory beyond a certain finite capacity. Therefore, digital memory cannot be adequate to the needs of a life form planning to survive indefinitely. Fortunately, there is no limited principle to the capacity of an analog memory built out of

a fixed number of components in an expanding universe. For example, a physical quantity such as the angle between two stars and the sky can be used as an analog memory unit. The capacity of this memory unit is equal to the number of significant binary digits to which the angle can be measured. As the universe expands and the stars recede, the number of significant digits in this angle will increase

logarithmically with time. Measurements of atomic frequencies and energy levels can also, in principle be measured with a number of significant figures proportional too, and then he refers to an equation log T. Therefore, an immortal civilization should ultimately find ways to code its archives in an analog memory with capacity growing like log T. Such a memory will put severe constraints on the rate of acquisition of permanent new knowledge,

but at least it is not forbid it altogether. WHOA, So I love that because he's he's really thinking big about about how even you know, memory and recorded history would work with a civilization that is this far advanced beyond what we have now. Again, what we have now does not scale up well, So ultimately Dyson is taking a very optimistic view of the ways that intelligence civilization could adapt to the changing physical environment of the universe.

At large, right, but again this was this was We've had some some some changes since then. And in fact BBC writer Adam Becker reached out to Dyson in um on the matter of of of the expansion in our universe seeming to accelerate, which which puts a new spin

on everything that we've discussed thus far. And uh, and so he reached out to Dyson, and Dyson said that he's he's far less optimistic, and that the most optimistic view is that perhaps the acceleration will slow down on its own, because he points out, we we don't know what's accelerating it, so it's still possible that it could stop um or slow down. Otherwise, Uh, he says, our descendants will lose touch with most galaxies, drastically limiting the

available energy that he's discussing in these models. And that sets us up in a pretty key way to talk about one of the papers we wanted to discuss today, a new paper from the physicist Dan Hooper. But first, Robert, did you want to mention a couple of other hypothesized ways that the universe could end? Yeah, yeah, they we'll throw these out here. The first one is the big change. This is in this a bubble of new lower temperature vacuum emerges in our own universe and expands at the

speed of light, converting everything in our universe. As Adam Becker wrote in that BBCO in his BBC article how will the universe end? And could anything survive? Um quote, the properties of fundamental particles like electrons and quarks could be entirely different inside the bubble, radically rewriting the rules of chemistry and perhaps preventing atoms from forming. Plus a dark energy inside the bubble might behave in a different matter,

perhaps causing collapse rather than expansion. So um this this sounds like a very problematic scenario if it where to come to pass. It almost is love craft Ian and it's uh and it's a scope right, the idea that suddenly here is an emergence of a part of our space that is not bound by the same rules. Yeah. Nice laws of physics you've got. There be a shame

if something happened to them. Now. Another another apocalyptic scenario for the universe is the Big Rip and this one was presented by Robert Caldwell of Dartmouth College in two thousand three based on the idea of phantom dark energy, in which the intensity of dark energy increases as the universe expands. So it's the density of of dark energy right now, as we understand it is pretty low, but if it builds up, it would rip the universe to shreds.

So maybe overcoming the other forces, Like right now we see dark energy increasing the distance between the galaxies out there. But things that are gravitationally bound to each other, or say bound by the nuclear force that holds atoms together, Uh, that stuff is pretty safe from dark energy. If dark energy said no, I'm going to overcome your gravity, overcome

your nuclear force, that would be a problem. Yeah, this is This is how Caldwell described it in his in his presentation quote, the positive phantom energy density becomes infinite in finite time, overcoming all other forms of matters, such as that of gravitational repulsion, rapidly bringing our brief epoch of cosmic structure to a close. The phantom energy rips apart the Milky Way solar system, Earth, and ultimately the molecules, adams, nuclei and nucleons of which we are composed before the

death of the universe in a big rip. Who gives a rip. So so that sounds that sounds terrifying as well. And on that note, let's take one more quick break and then we'll return to the discussion. Thank you, all right,

we're back. Okay. So what spurred this whole conversation was that we wanted to talk about a highly speculative but very fun paper that just was just published online by the physicist Dan Hooper, in which Hooper tries to imagine and scientifically characterize a survival strategy for a galactic civilization that sees the writing on the wall about the long term fate of the universe and decides it wants to survive as long as possible, because it turns out, if

you are a galactic civilization, you don't need to wait until the cold death of the entire universe to have a problem. You just have to discover that usable energy is becoming scarce where you live. Hooper's paper is called Life versus Dark Energy, How an advanced civilization could resist the accelerating expansion of the Universe. Uh. And we should point out that this has not been published in a

peer of view journal yet or anything. This is just something he put out on the internet ahead of publications so people could comment on it and talk about it. I think it may eventually come out in the Journal of Cosmology and Astroparticle Physics, but we'll pay attention there. But as always with anything that hasn't been uh been put through peer of view yet, grain assault. So who

is Dan Hooper? He is an associate professor of astronomy and astrophysics at the University of Chicago, and he's a senior scientist and the head of the Theoretical Astrophysics Group at Fermi National Accelerator Laboratory. And a lot of his work focuses on the intersection between particle physics and the evolution of the universe at large. So he's interested on where the biggest stuff we know about in the smallest stuff we know about effect one another. So what's what's

Hooper's argument about the future survival of a galactic civilization. Well, he turns his attention to dark energy what we've just been talking about, So on the scale of the universe at large, not necessarily in our own local neighborhood, but averaged across the entire observable sky, we've discovered that the energy that dominates the vacuum of space is not gravity, not electromagnetism, not any of the normal forces that govern our lives and our solar system, but a poorly understood

form of energy that we call dark energy, which drives expansion of the universe. So mass and gravitation attract objects to one another, dark energy drives them apart. It's the energy that causes the space between galaxies to spread, meaning that the whole universe is growing larger and all the stuff within it is growing farther apart, and the galaxy is farthest away from us are receding from us the fastest.

So as far as we know right now, dark energy might not have any practical applications for life bound to Planet Earth outside of scientific research, that is. But then again, we should know better than to dismiss the usefulness of any scientific discovery ahead of time. I'm always reminded of the English physicists who is credited as one of the discoveries of the electron, J. J. Thompson, who originally thought that the electron, which he was calling it the corpuscles uh.

He thought this particle he had discovered would not be very useful outside of the lab, had no idea had anything to do with electricity. But Hooper points out how once a civilization expands to a S and scale and its energy needs scale with that expansion, dark energy becomes a pressing concern for the future of that civilization. And this is because dark energy presents us the future of an encroaching cosmic horizon. So we are unable to interact

with anything beyond what's known as our cosmic horizon. This is the distance beyond which it is impossible to see because light from beyond this distance will never have time to reach us. Beyond that distance, everything is causally cut off from us. We can't see it, we can't talk to it or travel to it. Uh. You can think about it this way with an analogy. Imagine that the city or the neighborhood you live in is expanding. Are you there, Robert, Yeah, I'm there. It seems to be

the case. Actually no, no, no no, no. What you're thinking of is the increasing density of the city you live in. More stuff is filling it. But instead you actually need to think of exactly the opposite. The distance between your house and other buildings is steadily increasing at an accelerating rate,

so at normal walking speed. You say, used to be able to walk to the post office or the grocery store and then back to your house in what half an hour something like that, But as the distance between your house and these locations expands, the trip starts to take forty five minutes than an hour, then longer and longer at normal walking speed. Now you could try to walk faster, you could run, ride a bike, drive a car,

and this would help. But eventually, as the space between the locations keeps expanding faster and faster, even these more powerful vehicles and methods of travel will take longer and longer to get you between locations, until eventually you reach a point where no vehicle you can get can make the trip because the distance between the two points expands

faster than you can travel. You could travel toward the grocery store at maximum speed for the rest of your life and never get there, and this would mean that the grocery store has crossed beyond your cosmic horizon from

your house. Uh So, now, beyond the cosmic horizon of the real universe, there might be lots of other stuff we can only see to our cosmic horizon, and beyond that it's possible there are other galaxies, stars, planets, but because the interaction, our ability to interact with all that stuff is cut off by the speed of light, we will never be able to touch it. We can't land on those planets, we can't send messages to those civilizations

or get messages from them. We're just cut off by the universal speed limit of the speed of light and a vacuum. So, for instance, if you had this vast galaxy spanning uh Empire where everything everything is kind of compartmentalized. You have all these different divisions of the empire, and maybe they're they're not even in direct communication anymore. They just kind of have periodic updates about what culture and

life is like in these distant places. But eventually you reach the point where they're just too far from each other for there to ever be contact again. Well, it would depend on how far away from each other they are, because if they're within a galaxy or even within nearby galaxies, within what's known as the local group. The local group is a cluster of roughly fifty something nearby galaxies, they will probably one day merge into the same big old clump.

The local group is gravitationally bound, so we're going to pretty much stick together with the other stuff in the local group. So it's the galaxies far far away we have to worry about. Right. So if if, for instance, if Star Wars films were actually made in a galaxy far far away beyond the local group, and they have to be shipped back to us, there would reach a point where we could receive no more new Star Wars films. It would be a tragedy, wouldn't it. That's why we're

stockpiling them now. We're getting as many per year as possible, because eventually it's going to pass beyond the cosmic horizon. Oh no, wait, I don't want to be misinterpreted, because I know there are actually people who like hate the last Jedi. I am not one of those. I liked it too. Um, but yeah, I've seen this all over the internet. People are like, people are like pulling their

hair out about how much they hated. I don't understand. Yeah, I mean they're talking about making a Boba Fett movie, Like, do not disappoint like five year old Robert lamb and and and and ruin the possibility of a boa Fett movie for because I know that that he really wants to see it now. We'll come back to the cosmic horizon and the universal speed limit in just a minute, but uh to to shift our attention to another issue.

It's often supposed that far far future civilization can keep itself alive and create usable energy by harvesting the energy from stars, and this is a good strategy. We we often think about future energy sources. We think about what like, oh, cold fusion or something like that, but these are paltry energy sources. Any kind of like human made reactor that we can can feasibly think of right now would be a very paltry energy source compared to what's already out there,

which is the Sun right that. I mean, that is the energy source for everything that we hold dear. I mean, there's there's a reason that we we have worshiped it as a god in in previous ages because it it essentially is the almighty in our solar system. It is our creator. It is everything you know. I mean, it is a thing I used to say that I haven't thought of in a while, but I still stand by.

Is that when you think about energy sources, really it's with a few caveats, it's all solar Yeah, Like if you're eating a steak or or a Caesar salad, what have you, you were eating uh, converted sunlight, Like this is sunlight you were eating. That's where the energy came from. It's just you're getting it downstream coal or oil or

something like that that you would burn. Fossil fuels that you burn have chemical energy baked into them that was created when ancient organisms photosynthesized with the with the energy of sunlight. They took carbon out of the air, used the energy from sunlight to make that into sugar that turned into chemicals later down the road that you're now

burning to power your car. And this is why Kardaschef Scale level two is to simply master a sign to say all this energy that is uh, it's maintaining the solar system. This is now all mine, right uh, And so how would you do that? I mean to come back to Freeman Dyson. We've discussed on the show before

the idea of the Dyson's Fear. The Dyson's Fear comes to us from Freeman Dyson, and he basically says, you know, a civilization in the future that has a lot of technological power and wants to get the most bang for its buck will just completely surround its star with the

equivalent of solar panels, right. And this brings me back to Star Trek, because I earlier was talking about Star Trek and you know, scaling up of our current models of life and all I do have to point out that Star Trek the next Generation is the first place I saw any mention or depiction of a Dycen sphere. And it blew me away then, and it still blows me away now. Yeah. I mean, it's fantastic to think about. Uh. And one of the ways that it's actually relevant to us.

I mean, obviously it could be relevant in the far future if we wanted to try to build something like this. It's not technologically relevant to us today, except in the sense that if we're doing say CT and we want to look for ways of detecting alien civilizations out there that maybe aren't beaming us radio signals on purpose or anything like that. One thing that Dyson proposed is, hey, you know, we could look for Dyson's fears out there.

I don't think he called them dycens fears, but I don't know Dycen spears Dyson clouds, but I don't know, I'm not true to what extent he referred to them with his own name somehow I doubt it. I don't remember, but uh, if he did, that kind of be awesome anyway. No, but I mean he was like, you know, you could look for this kind of thing, and so people people have looked for this kind of thing. It would have

a certain kind of signature. One of the things that we could observe about a Dicen sphere is that if it completely surrounded a star and turned all of the stars solar radiation into usable in gy that could be used by the civilization somehow to survive after all, that, it would have to have a waste product, which would be heat, which we would be able to see as

infrared radiation, like submillimeter infrared radiation. And so if you see like darkened stars out there that are not producing any kind of light you can see, but are producing infrared radiation and the certain kind of with a certain kind of band, you've gotta wondering, is this just a giant hot ball that's taken everything a son's got, using it and then spitting some heat into space. Now, because sons and stars are already plentiful and they're already a

great source of energy. I think it is a fairly safe assumption to think that if there is a galactic civilization anywhere, will try to make use of something like a dicensephere, maybe not exactly the original design, but he will try to use stars as an energy source to sustain the civilization and feed its people and power its machines and do all that kind of stuff. And they're gonna need more than one. Yeah, and as the civilization scales up, it will need more and more energy needs

scale up with population increasing. So what if your galaxy runs short on stars? You've got them all sphered up, all the usable ones, and you're getting all the energy you need from them, but your population is still growing. What do you do then? Yeah? I mean you're essentially using all of your farmland here to produce the crops that are necessary for life, or that the model of life that you've built. And uh, yeah, what what do

you do when you maxed out? And then what do you do when say one of the stars blinks out on you? Uh, You're gonna have to scale back on what you can do as an empire. Stars also have finite lifespans. You eventually are going to need new stars to replace the old ones that are that are running down their fuel. Now, one thing you could do is just continually keep expanding, right, You could expand other galaxies.

I mean, this is this is very crazy and very far future, because we don't have anything like the ability to travel to another gal see today. But if you imagine one of these Cardashev three type civilizations that has mastered in an entire galaxy, it could spread to other galaxies. It could keep on expanding. But we're limited to our

local group right now. Because if you imagine just trying to continue expanding to other galaxies beyond into the far future, you would eventually come up against the problem we were mentioning earlier, the cosmological horizon problem. That's right, because even if you imagine and that releast is what I'm imagining, is that you know, just cosmic marauders. And this is

something that is Hawking has has touched on himself. Uh, and to a certain extent I think was touched on and that uh in the film Chronicles of Riddic and that it's kind of what the necromongers were doing, right. I don't think they're doing it with stars. But you know, they had the whole kind of like life sucking undead um, you know, ravager kind of thing going on. I mean I never saw Chronicles. Well, yeah, you've got to see it. I've seen Pitch Black at your recommendation. Well, that's the

necessary precursor to Chronicles of Riddic. You should see it. Is Keith David in it? Yes, okay, yeah, it's it's it's fun. It's fun. But yeah, I'm picturing a marauding um interstellar civilization. It just goes from one system to the next, using up sons and then spitting them out again. But eventually they're going to reach that point where there are no new sons to conquer. And Alexander wept where there were no worlds to conquer. Yeah, and then you're just left to uh just stew in the in the

cosmic darkness. Uh So, if we're gonna keep expanding, we need stars, and if we run out of local stars, we're gonna have to get him from somewhere else. And Hooper writes, quote over the next approximately one billion years, so basically times the age of the Earth. He writes, all stars residing beyond the local group will fall beyond the cosmic horizon and become not only unobservable but entirely inaccessible.

So he's saying, like, we're going to run out of time if if you know, a civilization doesn't do something early on, it's going to run out of time to get at all those extra stars to give them, to give them more energy. So you've got stars speeding away, how do you make use of them for the future. Hooper has an idea. What if you go out to those stars, you go snag them, and then you use the Dyson's fears that you build around them as a drive. We talked earlier about the idea of scattow thrusters and

things like that. What if you used a Dyson sphere to steer and drive a star back home to where your civilization is, so that you can hoard stars from the entire universe at large and keep them nearby to use them for the future before they go beyond your cosmic reach. I think we should call this star jacking. That's what it sounds like to me. It's star hoarding.

And so the the emitted radiation from a star could provide some thrust which could be used at least in theory, to steer a star are and it s Dyson's fear in a particular direction, meaning that you know, this civilization could gather stars close together and keep them from expanding out of reach and great leaks in the lifespan of their civilization. But there are limits on this, and a lot of Hooper's paper is used to calculate types of

stars that would be fruitful for this. Only certain types of stars would work, mainly stars somewhat within the range of the mass of our Sun, because stars that are much bigger tend to be older or tend to not have as much life left in them. Yeah, you don't want to go to the trouble of Jack and those stars if they're just going to burn out or collapse before you can make use of them exactly. So this

is a problem. The bigger stars would not have enough life left in them to survive the journey back to the home base, and so they're not really worth hoarding. On the other hand, stars much smaller than our Sun would not provide enough energy to drive the star to its central star Hoarde fast enough before it passed beyond the cosmic horizon, and so there is kind of a

Goldilocks star. You know, a Goldilocks star that you want that that is big enough to give you enough energy, that's small enough that it's still going to have plenty of life left in it by the time you get at home, And that's the kind you want to bring home. Interestingly, Hooper points out that if alien civilizations anywhere out there are doing this quote, this would not be a subtle activity, so we should be able to detect it. Kind of

like the original idea of the Dicen sphere. If anybody out there is doing anything like this, you've got a galactic civilization in one of those galaxies far out there, and it's making these kinds of preparations for the future. This could give us a new path to setty observation. Can we look out at galaxies out there and detect the removal, transport, and hoarding of certain kinds of stars? Yeah, I mean it makes it makes sense. Like you said,

this would not be a subtle act. This would be the kind of thing that we would conceive will be able to observe. Yeah, and so Hooper writes, quote, such a civilization could pier as a region up to tens of mega par sex and radius in which most or all of the stars lighter than about two solar masses are surrounded by Dyson's fears. Now that's a cool image. Yes, the star hoarde, the star hoard Yeah, there the empire of the star hoarders or star jackers, which whichever one,

whichever one you want to use. Star jacking is the verb, the star hoarde is the Now the star jackers work for the star hoarders. Yeah, and then our only hope is to just, I guess, somehow present a case that we're we're worth keeping around, like we're culturally interesting enough, or maybe they have rules. Maybe they don't take stars from systems with the inhabited worlds. I don't know, I could go virtually anyway. Yeah, maybe they only use stars

from inhabited worlds. Now, of course, with an idea this far out there, you at least want to hear what some other scientists in the field have to say. Fortunately, there was a right of this in Science News that got some quotes from some other astrophysicists, for example, the

theoretical astrophysicist Katie Mack of North Carolina State University. They asked her opinion and She pointed out that, you know, one thing is that you might have an easier time surviving if you just uproot your civilization and move it to a different galaxy cluster that's got a bunch of different stars you could use. So instead of bringing all the stars to you, you just go where they're already are, a whole bunch of already untapped stars the Marauder model, Yeah,

and settle in there. But then again, you know, maybe they maybe there are reasons they want to stay where they are. It might be easier to send out autonomous star collection, you know, robots that would build Dyson's fears around stars and bring them home than it would be to move the conscious inhabitants of a place. Maybe they like where they are and the movement would be stressful. Yeah, I mean, ultimately, who's going to argue with them? Right? Right?

Because they would be where would they be on the Kardashi of scale, they would be between two and three, Perhaps they would be threes. I don't know, three, it's pretty lofty. Oh yeah, I think we're talking about a level three cardship civilization right here. You're you're controlling a galaxy. If you're going out to other galaxies to get stars to bring home. Yeah, yeah, you would be Yeah, so I guess you would be a little beyond three. You

would be up towards us. You would be moving towards four. Whatever. Four would be like if we can even comprehend such a thing, a mastery of the local group or something. The physicist Avy Loeb of Harvard University also points out the same issue that you know, it might not be necessary to go get stars from other places, because he says, quote,

nature did it for us. You've already got There are places in the universe where they're huge clusters of galaxies that are all sort of near by each other, and maybe it would be better to go to one of those galaxy clusters that's got lots of stars already there. I mean, it's it's a relative lots of stars, because

there are lots of stars in our galaxy. But if you're talking about this Cardassian you know, three point five or four type civilization and it's got ridiculous energy needs, then there are places you could go that would have more stars nearby already. Right. And again this is assuming they don't say, you know, guys, this is a bit nach.

We don't need this much energy, let's scale back a bit. Yeah, But then again, our tribal ancestors could have said that about our world today and now here we are and we need the energy. True though there we do, see, I mean, there obviously is a movement to cut back on energy to find more sustainable ways. Uh you know, whether that will that argument will win out in the end, uh you know, remains an open question. But um, well,

I would say, I don't know. Maybe maybe you can make the case to me, I don't know if any good reason that we need to cut back on energy itself is just like types of energy, you know, certain types of energy are more destructive than others. And if we had a truly I mean, I think there is no such thing as a perfect energy source, because even the most benign forms of energy maybe solar, wind power, whatever you have, have some kinds of construction and costs

and stuff to build the panels. Um. But but there are relatively benign forms of energy that I don't I don't know. Is there an argument that we shouldn't even be trying to maximize our collection of solar energy or something? No? I mean it kind of comes down to though, to like how much energy can we conceivably harvest? And then how are we living our lives in accordance to it?

You know? Um? So I yeah, I don't see anybody as saying let's stop harvesting energy, but but also asking the question, is our consumption lining up with our current and even near future ability to harvest it? Maybe the answer to that is no, right, yeah, but but it's certainly based on our own model of intelligent um technological behavior, it makes sense that uh, an alien species, we just continue to jack as many stars as as as possible

to sustain itself. I mean, I I like I was saying earlier, I think we want to avoid making too many assumptions about future civilizations or alien life, because there's a lot we just can't know about their minds, about their culture and all that. But one thing we pretty much know no matter what is they need energy. Yes, but I'm saying they could scale back if they if they really wanted to. I mean, it's I think that

is a possibility. And certainly if they see the writing on the wall, you know that that energy is going to become less abundant, and then it's about survival. Now, speaking of survival, um, I do have one last survival scheme dimension here, and this one was exploring in that Adam Becker BBC article their referenced earlier. Alan Gooth of m I T contends that the laws of physics might imply that that this is possible, uh, that you could

essentially escape into a universe of your own making. Yeah. Now, it would require vast amounts of energy, which of course is we're discussing the players in this kind of game would have have. But it might go down like this. First of all, you need to create an incredibly dense form of matter, so dense that it barely avoids collapsing into a black hole, and you quickly clear the matter out of the way, forcing the region of space to start expanding, and this would jump start, in theory a

new universe. Quote. As the space in the region expanded, the boundary would shrink, creating a bubble of warped space where the inside was bigger than the outside, which is kind of like it reminds me of the bag of holding from Dungeons and Dragons. The Gooth actually compared it to the tartest dr who looked it looks bigger on the inside. Yeah, yeah, and they on the outside it's what a phone phone booth, and then on the inside

it's this large, expensive room and so forth. So eventually the new universe would pinch off from the old doomed universe. But he stresses that this might not be possible at all. Sure, it depends on a lot of assumptions that could be true, but we don't know for sure. But then also the other way of looking at things, he says, is it, Uh, you know, if if the multiverse model holds true, then that's probably our best bet. The universe may end, but

the multiverse continues eternally. No way that that might mean though we can't get there, just some other version of us. Yeah, and but that might be the best we can you know, for in the end is just to realize, all right, we've we've we've jacked a thousand stars, we've hoarded them, we've done what we can. But hey, the writings on the wall, we're gonna blink out. But somewhere out there in the multiverse, Uh, this thing called life is still going.

I believe in the thing called technological civilization. One final note is a side tangent. Well, one thing I loved about the Freeman diys in paper we talked about earlier from seventy nine, is that at the end he invokes holdings, uh, quoting of of G. K. Chesterton on the role of human intellect in the future of of of civilization quoting from the Ballot of the White Horse by Chesterton, where he writes, so rides my soul upon the sea that drinks the howling ships, though in black jest at bows

and nods under the moons with silver rods. I know it is roaring at the gods waiting the last eclipse. Oh that's nice. So maybe find peaceful ways to survive that last eclipse. All right, So there you have it. If you want to hear more episodes like this dealing with the the long term future of humanity and this universe of change and hostility, uh, then you can check out all the episodes of Stuff to Blow Your Mind at Stuff to Blow your Mind dot com. That's the

mother ship. That's where you'll also find social media links to our Facebook, Twitter, Instagram, you name it. Huge things as always to our wonderful audio producers Alex Williams and Tary Harrison. If you want to get in touch with us to let us know feedback on this episode or any other, or to suggest a topic for future episodes, or just to say hi, let us know where you listen from. You can email us at blow the Mind

at how Stuff Works dot com. And I want to close out here with a really cool tray guy came across from the group We Plants Are Happy Plants, titled an Incredible Pearl, which makes use of a passage from American writer philosopher in ethnobotanist Terrence McKenna, who who we discussed on the show in the past. Kind of a wizard figure. Yeah yeah, so, uh so check this out. If you want to hear more from We Plants Are Happy Plants to simply look them up on Spotify or iTunes,

wherever you get your music. You can also go to YouTube dot com, slash w P a h P. We're going to have to make a decision about human nature to wit. Is this our home to be cherished and nurtured, an incredible pearl flung out in a universe of ashes and darkness? Or is this a hell world, a tiny, confining prison at the edge of a dying universe from which it is our destiny to break free and recover our higher and hidden nature from which we have become separated.

You know, this is a choice which as a culture we face. Are we to go into the divine imagination and create you know, starships the size of Manitoba that will apply between here and Andrama and exist in a world of our complete syntactical self expression. Or is man's

place humbler than that? Is that grandiose steeped with megalomania, touched with the kind of political taint that's had this raping and pillaging ever since we got out of those miserable ice bound villages in Jutland or wherever it was. Is it that? Or is it our challenge and our destiny? It's really a choice about human nature.