Posted it because it reminds me of an hypothesis I once saw, that we might be able to detect alien civilizations based on blank spots in the sky where they've managed to divert all the energy from their environment.
I'm reminded of the Three Body Problem series, where there's this concept of a Black Domain - an area of space in which the speed of light has been reduced drastically. Some civilizations in the setting have reason to deliberately construct these areas of space. (The reasoning behind this might be considered a spoiler, so I'll leave it off.)
Sounds similar (I still need to read Liu), but in Vinge, it wasn't light speed being reduced, it was a variety of limitations on superluminal physics, computation/intelligence, and maybe even physical properties. (variations in quantum physics, perhaps)
Sort of. In Vinge's world, the slow zone is just a natural phenomenon, not something artificially created. And in the slow zone you're basically limited to nearly-speed-of-light travel consistent with our contemporary understanding of relativistic physics (which is unbearably slow to anyone who can travel much faster than that outside the slow zone). Whereas in Liu Cixin's books, if I remember correctly, they actually change the speed of light itself to be even slower.
If I remember correctly, there's some ambiguity whether the slow zone was created by some power or naturally occurring (or a bit of both) although a bit of both is perhaps the natural answer.
I remember some insinuations to that effect, but from an unreliable narrator given Vinge's penchant for strictly in-character exposition, and what would child races know of progenitor's motives?
As a universe arrangement scheme (both narratively and literally), it is a clean solution to providing a new race incubator and preventing "Why don't the First Ones rule everyone?" endgames.
It might not be as empty as it looks. Maybe it’s just got a really big dark sheet over it. Astronomers don’t consider the possibility of ginormous dark sheets in space.
I've heard this idea in the context of Dyson spheres/swarms. The issue is that, while they'd be invisible or dim to the eye, the areas would be very bright in infrared.
Depends on how large the swarm is. Using our sun as the example a 1AU swarm would be very warm, but at 100 AU it would be extremely cold and much harder to detect.
Really though, a Dyson’s swarm isn’t that efficient long term. It’s likely better to dismantle large stars and use fusion reactors with heat sinks at close to 2.73 Kelvin as possible.
Fossil fuels vs solar, it’s a sustainability question. Plus, dismantling a sun isn’t much help to the planets orbiting it, and then you need to find a way to efficiently get that energy to another system to be used.
Planets ? Who cares about planets when building a Dyson swarm - other the possibly as a bootstrap cache of materials to get thing going.
Yeah, you might occasionally leave one in place for historical reasons, but otherwise they are just too useless not to make use of their mass for something better. Not to mention traffic management headaches given that normal planets usually stubbornly refuse to do any orbit corrections when needed.
The amount of fuel is fixed either way so it’s an efficiency question. Normal stars only burn a small percentage of their fuel. Maximum energy is captured by turning hydrogen into lead. After that, dumping lead into a deep gravity well is the final option.
> Really though, a Dyson’s swarm isn’t that efficient long term. It’s likely better to dismantle large stars and use fusion reactors with heat sinks at close to 2.73 Kelvin as possible.
Would like a referral to science fiction that talks about this.
Whole star system optimized into a giant computing cluster with projected sun energy output for computing available for next 14 trillion years:
https://orionsarm.com/eg-article/49125f5d1c049
(Or 100000 sun output for 140 milion years.)
Himmelsschmiede - a full star system converted to useful heavy elements using a deep well industrial zone (basically an artificial black hole accreation disk):
https://www.orionsarm.com/eg-article/46709da5de6be
The whole concept of Dyson Spheres, or anything even vaguely like that, is totally absurd. (Even Dyson said so.)
Any space-faring culture will have mastered controlled fusion long ago, and have entirely left behind any material dependence on stars. The best places to live, then, are out in the Kuiper belts and beyond, where unlimited room and cold are available for free, and valuable gases are lying about, frozen. Inner planets are for extreme primitives. If aliens got here, they would find Triton much more interesting than Earth, except maybe as a curiosity.
Expanding menace civilizations will run up against overwhelmingly more advanced stable cultures before long and be contained or destroyed, so odds are none could get here before that happens.
Unless you can harvest interstellar medium at scale stars are where most mass is locked up, conveniently in a single place even. Outer belt objects are quite small in volume in comparison and inconveniently far from each other.
The outer belt objects are small compared to planets, but are enormous considered as extracted volume, and uncountably numerous; whereas on inner planets you are effectively limited to the solidified skin at the bottom of an annoying gravity well, bathed in heat that must be shed.
Kuiper belt distances are inconvenient only when you are in a hurry and have limited speeds. Given fusion propulsion, nothing inside a solar system is especially far from anything else. But a large volume to operate in, which grows as r^3, is valuable, and an unlimited sink of cold, moreso.
Good point - the exposed surface are for easy mining is pretty massive for outer system objects & accessible without the need for advanced stuff like planet cracking and solar lifting.
With sustained > 1G we are effectively talking torch drives, not just "normal" fusion drives. Not many technologies we know of that might pull that off, possibly with the exception of nuclear salt water rocket.
Anything we could ever cobble together is necessarily unspeakably primitive when compared to what the Oort Cloud "elder gods" perfected lo untold eons before primates first chipped rocks.
To add, we are only just beginning to experience a hint of the plague of excess exhaust heat. It only gets worse, and the Third Law of Thermodynamics is a harsh mistress.
Well, for how bad it can get one can check Puppeteers home world in Nivens Known Space universe - that damn planet shines white in visible spectrum in many places due to waste heat and they indeed had to move it farther from their sun.
>Expanding menace civilizations will run up against overwhelmingly more advanced stable cultures before long and be contained or destroyed, so odds are none could get here before that happens.
This seems like an interesting thought experiment care to expand on that?
An expanding menace culture will also be young, just because anything growing fast can't have been doing it for long. By comparison, a stable culture can stay that way indefinitely, spending its resources accumulating knowledge and skills instead of on expanding, and so can accumulate a very great deal of both over a vast stretch of time. It has perhaps less access to materials, but a solar system has a great deal of material to start with, and it is not stretched thin.
When an expanding menace tries to absorb the ancient stable culture, it has key disadvantages. Its attention is spread over activities on a large periphery, and its stores of knowledge and weaponry are limited. The ancient culture has been found by many menaces before, and survived them all. It knows of other old, stable societies, and they may even have evolved a common plan for dealing with menaces.
It is conceivable that the expanding menace would try to flow around the old stable societies, like a river around rocks, without threatening them enough to provoke a backlash, but that runs against the logic of expansion.
So, odds are any expanding menace will encounter one of them, or more than one, if needed, before it gets to us. Each such encounter will be an existential challenge at bad odds, which multiply out increasingly close to zero.
Thus, the stable condition of a galaxy is a sparsely occupied archipelago of deeply ancient, unassailable cultures not interested in expansion, so not visiting, e.g., us, with the occasional rash of menace, dealt with firmly.
Are you arguing that the expanding menace culture must be young because such cultures wouldn't last long because of conflict? I think a lot depends on how densely populated the universe is. At a limit imagine one long lived intelligence per galaxy. You could have a poisonous disease the size of a galaxy 10 million years old sending out spores to poison adjacent galaxies. Maybe we are even the present genesis of this.
As you adjust down you could trivially and likely have tens of light years between cultures or even hundreds on average if intelligent cultures are short lived or particularly rare. Expanding menaces could be automated and self replicating and designed to create an expanding zone of safety for an old stable society in a way that isn't easily traceable to the old stable society.
> "Are you arguing that the expanding menace culture must be young because such cultures wouldn't last long because of conflict?"
It's young because it's expanding. To first order, divide the radius by the rate of expansion and you get when it started. The society that bides its time for millions of years and then turns menace does not pass the smell test. Every year they go without menacing, the less likely they ever will.
Anyway, whoever's (1) inside the perimeter, (2) is a bad trading partner, and (3) not burnt is a pretty good bet for who's responsible. If there are two plausible candidates, they are better both dealt with.
It's also true that they don't last long because of conflict, but that's secondary.
A sorcerer's apprentice scenario is conceivable only in the short term. To maintain expansion demands adaptation to an increasing variety of new challenges, whose variety and strength increase as the fourth power of expansion radius. (Three dimensions for space, one for age of opponent.)
One can invent myriad obscure scenarios, of decreasing likelihood. It's a big universe, rashes happen, but it's a big universe, so they mostly happen somewhere else.
this is an interesting observation, and it plays out exactly like this many times over in the 'Stellaris' RTS game.
Stable societies that stick to their own region while prioritizing research ('growing tall' is the name for the strategy) tend to win out in battles against those that 'grow wide', grabbing all resources and expanding into them with little regard to research and personal affairs.
Those that 'grow wide' tend to win the games through simple attrition on a long time-span at the end-game phase. Simple resource volume tends to be able to win against vastly superior forces, much like a StarCraft 'zerg-rush', and the superior force usually loses in a 'death by a thousand cuts' fashion -- but individual battles before this phase of the end-game are almost exclusively won by small civilizations that 'grow tall', much like the 'stable culture' of your example.
The 'Growing Tall' strategy tends to be the one chosen by players who like to end games early and play aggressively against the other players -- contrary to the sedentary and passive method of play that the strategy facilitates.
In Stellaris, everybody starts at the same time, right? And, close enough together that they are sure to encounter one another pretty early? And, material resources actually matter?
It seems like being equipped to, say, cause a solar flare to sterilize an offending planet would tend to discourage an aggressor before their ships got used up. Probably a flare wiping out a neighboring planet (e.g. one like Venus) first would convey the message adequately.
What seems downright absurd to me is to dismiss the obvious fact that while a star might be incredibly inefficient relative to a working fusion reactor, the actual energy output of a star will far outstrip that which can be collectively produced by artificial fusion for many centuries and millennia to come.
Stars provide in abundance and for free, energy, mass (even for heavier elements they far outstrip that available on planets, asteroids, and comets), a star system spanning magnetosphere for protection from the interstellar medium, and a massive gravity well which can be used to anchor planets and mega structures alike
While it's true that we won't strictly "need" them once we have working fusion, they are likely to be the hotspots of civilisation for a long time to come, probably as long as the stellar epoch of the universe is in play (so 100+ billion years).
For most high-civilization activities, heat is pollution, something that must be extracted and shed, in volume. Out in the Kuiper belt, cold is abundant and free.
For most high-civilization activities, a gravity well is an anchor chain. Out in the Kuiper belt, material resources, including frozen fusible gases, are abundantly accessible with very little annoying gravitation.
For many high-civiliation activities, proximity of other entities that could be put at risk, or that might put you at risk, creates hazards. Out in the Kuiper belt, room enough for anything is abundant and free.
Extreme primitives like us and bacteria, who don't have abundant private energy sources, welcome the low-intensity energy influx from a nearby star. For anybody even mildly sophisticated, the energy is uselessly diffuse. At the same time, it keeps everything at a noisily high temperature that interferes with signal integrity and fine-grained processing.
This is too much of an extrapolation even by the standards of envisioning things like Dyson Swarms. You are assuming that:
* It is possible to export or even host consciousness onto a digital medium - we still have no evidence for this
* All or most civilisations ultimately will want to transition entirely into a digital existence - the "entirely" part is important. If even 1% of a K-2 civilisation decided to stay organic, that would still lead to a Dyson swarm with a population approaching trillions.
* Civilisations of this tech level would do a cost benefit analysis and decide that the several orders of magnitude more resources on a star is outweighed by the inconvenience of a gravity well - I don't think orbital rings are that mass or energy intensive to build and run for this to make any sense
* There will be no future use of waste heat or method of disposal that goes beyond simple dispersal - the jury is still out on that, it may be possible to dispose of waste heat directly onto a black hole. If this turns out to be correct, the energy of a star is more than enough to power a sufficiently powerful laser array to create many in the gigatonne range.
Why would we presume they would not think to generate a cloaked for this if they had the ability to divert all energy from their environment? Seems an obvious first order of business to avoid looking like an anomaly if you are not actively trying to be found.
What makes us so sure waste heat is something that is absolutely unavoidable. It’s possible heat maybe be disposable through some quantum means we have not uncovered yet. Ultimately everything in existence has heat potential so theoretically heat is able to covert back to everything else . Using no heat as proof the room is empty is equivalent of a person who cannot avoid making a mess when they enter a house concluding that no one else has been there because there is no mess (except the one they made) all they can conclude is that no one who makes a mess has been there.
Sometimes I wonder about the percentage of HN commenters who actually read the article. Literally a few paragraphs in:
“The lack of radio sources means that there are no galaxies or clusters in that volume.”
This morning, on an article about 'fuck-you money' there was a discussion about where the term comes from. The 1990s? The 2000s? The first paragraph of the article dated it back to at least the 1920s.
See, I was prepared to downvote the comment. But then you commented, and someone else did, too. So, they actually did spark conversation. Now I have to upvote, I guess.
I usually click on the comments, if an article seems interesting I’ll see if the comments say it’s bad etc before clicking but even articles I’m not interested in but have an interesting topic I’ll click through to read the comments.
This one, for instance, I’ll admit I haven’t clicked through to the article. I’ve long been interested in these voids so I didn’t figure the article would relay any information I wasn’t aware of so I clicked through to see what people here had to say.
I've considered if a discussion site like this would work solely based on the headline without actually needing TFA. Often it feels like people who comment just want to share their point of view about a particular topic rather than the article itself. Many people read the comments first (or exclusively).
Perhaps Dang could get analytics on how many people viewed the comments and how many people clicked through to the article to answer your question.
The parent commenter is correct, and you (despite your username) and the article are not. If you read the paper it notes a dip in radio sources, not a complete absence of them. An entirely empty void a billion light years across is essentially too improbable to exist. “Voids” are just areas with fewer galaxies, relatively, not places with a none of them. In fact, the Milky Way (and the entire Local Supercluster) itself is in a void called the “KBC Void”.
"an immense, comparatively empty region of space...proposed to be roughly spherical, approximately 2 billion light-years in diameter. As other voids, it is not completely empty but contains the Milky Way, the Local Group, and a larger part of the Laniakea Supercluster. The Milky Way is within a few hundred million light-years of the void's center."
A void has by "working definition" "less than one tenth of the average density of matter abundance that is considered typical for the observable universe."
The article is dated 2007, and much more has been learned about the WMAP cold spot in the past almost fifteen years.
Tracing out how the very earliest structures in the CMB compare with much more recent galaxy filaments (and the voids between the dense filaments) is an interesting area of research, and there will be open questions for many years to come as galaxy surveys at different redshifts produce observational data.
(All the galaxies will be at a lower redshift than the CMB cold spot, and it is a good guess that the CMB cold spot reflects an arrangement of matter much closer to the hot big bang or cosmic inflation than that. Perhaps one day our descendants will be able to examine the cosmic neutrino background to see if it too has a comparable cold spot, and the same with primordial gravitational radiation; alternatively perhaps they will discover that later-time physics distorted the CMB very slightly. The latter hypotheses are in practice much easier to test with observational data, and of course one can exploit the many unknowns in the dark matter and dark energy sectors without colliding with constraints from known physics.)
Please don't comment on whether someone read an article. "Did you even read the article? It mentions that" can be shortened to "The article mentions that."
It should be the other way around. When everything is packed closer together you are far more likely to fall victim to supernovas, more asteroids and so on that can end life on your planet.
Imagine being a civilization alone in the void, and not even a generation ship could make contact with anyone else, even if they knew which direction to send it.
This article was written in 2007 about the Giant Void. [0] In 2013, the KBC Void [1] was discovered, named after its discoverers, Keenan, Barger, and Cowie. The KBC void is 2 billion light years across, twice the diameter and 8 times the volume of the Giant Void. Both the Giant Void and the KBC Void contain galaxies, the Giant Void containing 17 galaxy clusters, and the KBC Void containing the Laniakea Supercluster. [2] The Laniakea Supercluster contains the Milky Way. Something to imagine, indeed.
The Local Void that we are on one edge of is about 150 Mpc across (~490 million light years) and contains several "void galaxies" such as NGC 6503, about 4 Mpc (17 Mly) from us:
Unfortunately that's actually what the future holds for the universe (as far as we can tell from current observations).
The universe will expand so much that civilizations into the VERY distant future will not be able to see other stars and galaxies, and will have no way to know that there's more out there.
Well, even one galaxy is too big for anyone. As one astronomer said, even one local arm of Milky Way is enough to fit all and every science fiction ever imagined. There's just too much stuff, that you don't need to think about other galaxies.
That's actually us - the Local Group (the Milky Way, Andromeda and other smaller galaxies, about 3 Mpc diameter) is part of the Local Sheet (about 5 Mpc × 0.5 Mpc) which is on the boundary of the Local Void (about 60 Mpc diameter).
> The void, which is nearly a billion light years across, is empty of both normal matter and dark matter. The finding challenges theories of large-scale structure formation in the universe.
How do they know or believe that it doesn't contain dark matter?
”The lack of radio sources means that there are no galaxies or clusters in that volume, and the fact that the CMB is cold there suggests the region lacks dark matter, too.”
Interesting inference, to make it we have to hypothesize that dark matter has an effect on the CMB in the first place, is that at least somewhat backed up by any observations?
The small fluctuations in the CMB that WMAP detected (the 2007 article being about the "WMAP Cold Spot") are sensitive to the distribution of all matter -- including dark matter -- in the early universe.
Roughly, hot spots have more matter, get hotter as that matter collapses
into stars, hot gasses, and eventually black holes; cold spots have less matter, and because of the expansion they get colder, sparser, much bigger, and eventually become practically empty.
Early pockets of dark matter overdensity, similarly roughly, helps turn on the heat very early, and keeps the heat turned on longer than otherwise. Early pockets of dark matter underdensity makes it much harder for stars to light up in the first place.
Generally one simulates the introduction of non-uniformities in this distribution during Cosmic Inflation, and then the overdense areas collapse while the underdense areas experience the cosmological constant. At the time the universe has expanded enough that photons can free-stream (this marks the beginning of the CMB, see [1]) the density-differences in one part of the universe to another are very small, but over billions of years the collapsing dense regions become ever denser (and form stars and galaxies) while sparser regions simply become colder. (Both become emptier, relatively; collapsing a diffuse cloud into a dense cloud leaves behind a lot of space emptier than when the diffuse cloud was populating it).
Dark matter plays a crucial role here, because it collapses more slowly than visible matter by forming haloes and other structures, essentially suspending visible matter (gas) above the cores of galaxy clusters (where in later times you find really gargantuan black holes). It is also important that its underdensities and overdensities after Cosmic Inflation were roughly the same as that of what became the particles of the standard model, and it is this feature that appears to be crucial to structure formation : https://map.gsfc.nasa.gov/universe/bb_cosmo_struct.html
However, once the CMB has formed, those photons no longer interact appreciably with the dark matter of the universe -- the gravitational interaction is weak and gets weaker with the expansion of the universe.
So it is the early distribution of dark matter (before atoms, before protons) that is important in creating CMB cold and hot spots.
It would be odd to have a hot spot become anything but a matter structure (galaxy cluster) because of gravitational collapse. Likewise, it would be odd to have a VERY cold spot become anything but filled with a very sparse gas (e.g. hydrogen + photons + neutrinos). The WMAP Cold Spot is not THAT cold and so could have structures like galaxy clusters in it, but fewer of them than than in the filamentary structures. Indeed, we may live in someone else's cold spot. Galaxy surveys are trying to gather up evidence one way or another for the densities of galaxies and their ages along various lines of sight from here, which will help us determine how well WMAP cold and hot spots line up with galaxies. ALL galaxies are much more recent than the CMB.
Several ideas about how the WMAP Cold Spot could have been a WMAP Average Spot at the time the CMB was formed, but that (mostly new physics) events in the more modern universe present us with a relative cold spot. Some of these have the virtue that these more modern events are more amenable to study with our current level of technology than the distribution of gravitational waves after cosmic inflation and the detailed study of the cosmic neutrino background (which is similar to the cosmic microwave background, and so should have similar small temperature fluctuations; but measuring ultracold neutrinos is not something we can do today, nor can we yet look at the frequencies and amplitudes of primordial gravitational waves, however there may be indirect probes of both...
While it's possible that post-first-light dark matter can cause caustics-like effects on the background microwaves via gravitational lensing, the fluctuations in the CMB that are anything like the |WMAP Cold Spot| are not plausibly generated that way, mostly because dark matter is simply too diffuse from the present age of the universe back to just after the formation of the CMB (which is the earliest possible time any structure can be in the foreground of the CMB). Barring something really unexpected, the Cold Spot is probably a relic of Cosmic Inflation, producing an atypical underdensity of matter-including-dark-matter.
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[ 3.0 ms ] story [ 145 ms ] threadAs a universe arrangement scheme (both narratively and literally), it is a clean solution to providing a new race incubator and preventing "Why don't the First Ones rule everyone?" endgames.
Really though, a Dyson’s swarm isn’t that efficient long term. It’s likely better to dismantle large stars and use fusion reactors with heat sinks at close to 2.73 Kelvin as possible.
Yeah, you might occasionally leave one in place for historical reasons, but otherwise they are just too useless not to make use of their mass for something better. Not to mention traffic management headaches given that normal planets usually stubbornly refuse to do any orbit corrections when needed.
Would like a referral to science fiction that talks about this.
Also used in many places in Orions Arm: https://www.orionsarm.com/eg-article/47897e8b1947c
Whole star system optimized into a giant computing cluster with projected sun energy output for computing available for next 14 trillion years: https://orionsarm.com/eg-article/49125f5d1c049 (Or 100000 sun output for 140 milion years.)
Himmelsschmiede - a full star system converted to useful heavy elements using a deep well industrial zone (basically an artificial black hole accreation disk): https://www.orionsarm.com/eg-article/46709da5de6be
Any space-faring culture will have mastered controlled fusion long ago, and have entirely left behind any material dependence on stars. The best places to live, then, are out in the Kuiper belts and beyond, where unlimited room and cold are available for free, and valuable gases are lying about, frozen. Inner planets are for extreme primitives. If aliens got here, they would find Triton much more interesting than Earth, except maybe as a curiosity.
Expanding menace civilizations will run up against overwhelmingly more advanced stable cultures before long and be contained or destroyed, so odds are none could get here before that happens.
Kuiper belt distances are inconvenient only when you are in a hurry and have limited speeds. Given fusion propulsion, nothing inside a solar system is especially far from anything else. But a large volume to operate in, which grows as r^3, is valuable, and an unlimited sink of cold, moreso.
If you need more mass, Neptune is right there.
Or, maybe you are robots, and can take 100G. Then the Oort cloud is your playground.
This seems like an interesting thought experiment care to expand on that?
When an expanding menace tries to absorb the ancient stable culture, it has key disadvantages. Its attention is spread over activities on a large periphery, and its stores of knowledge and weaponry are limited. The ancient culture has been found by many menaces before, and survived them all. It knows of other old, stable societies, and they may even have evolved a common plan for dealing with menaces.
It is conceivable that the expanding menace would try to flow around the old stable societies, like a river around rocks, without threatening them enough to provoke a backlash, but that runs against the logic of expansion.
So, odds are any expanding menace will encounter one of them, or more than one, if needed, before it gets to us. Each such encounter will be an existential challenge at bad odds, which multiply out increasingly close to zero.
Thus, the stable condition of a galaxy is a sparsely occupied archipelago of deeply ancient, unassailable cultures not interested in expansion, so not visiting, e.g., us, with the occasional rash of menace, dealt with firmly.
As you adjust down you could trivially and likely have tens of light years between cultures or even hundreds on average if intelligent cultures are short lived or particularly rare. Expanding menaces could be automated and self replicating and designed to create an expanding zone of safety for an old stable society in a way that isn't easily traceable to the old stable society.
It's young because it's expanding. To first order, divide the radius by the rate of expansion and you get when it started. The society that bides its time for millions of years and then turns menace does not pass the smell test. Every year they go without menacing, the less likely they ever will.
Anyway, whoever's (1) inside the perimeter, (2) is a bad trading partner, and (3) not burnt is a pretty good bet for who's responsible. If there are two plausible candidates, they are better both dealt with.
It's also true that they don't last long because of conflict, but that's secondary.
A sorcerer's apprentice scenario is conceivable only in the short term. To maintain expansion demands adaptation to an increasing variety of new challenges, whose variety and strength increase as the fourth power of expansion radius. (Three dimensions for space, one for age of opponent.)
One can invent myriad obscure scenarios, of decreasing likelihood. It's a big universe, rashes happen, but it's a big universe, so they mostly happen somewhere else.
Stable societies that stick to their own region while prioritizing research ('growing tall' is the name for the strategy) tend to win out in battles against those that 'grow wide', grabbing all resources and expanding into them with little regard to research and personal affairs.
Those that 'grow wide' tend to win the games through simple attrition on a long time-span at the end-game phase. Simple resource volume tends to be able to win against vastly superior forces, much like a StarCraft 'zerg-rush', and the superior force usually loses in a 'death by a thousand cuts' fashion -- but individual battles before this phase of the end-game are almost exclusively won by small civilizations that 'grow tall', much like the 'stable culture' of your example.
The 'Growing Tall' strategy tends to be the one chosen by players who like to end games early and play aggressively against the other players -- contrary to the sedentary and passive method of play that the strategy facilitates.
It seems like being equipped to, say, cause a solar flare to sterilize an offending planet would tend to discourage an aggressor before their ships got used up. Probably a flare wiping out a neighboring planet (e.g. one like Venus) first would convey the message adequately.
Stars provide in abundance and for free, energy, mass (even for heavier elements they far outstrip that available on planets, asteroids, and comets), a star system spanning magnetosphere for protection from the interstellar medium, and a massive gravity well which can be used to anchor planets and mega structures alike
While it's true that we won't strictly "need" them once we have working fusion, they are likely to be the hotspots of civilisation for a long time to come, probably as long as the stellar epoch of the universe is in play (so 100+ billion years).
For most high-civilization activities, heat is pollution, something that must be extracted and shed, in volume. Out in the Kuiper belt, cold is abundant and free.
For most high-civilization activities, a gravity well is an anchor chain. Out in the Kuiper belt, material resources, including frozen fusible gases, are abundantly accessible with very little annoying gravitation.
For many high-civiliation activities, proximity of other entities that could be put at risk, or that might put you at risk, creates hazards. Out in the Kuiper belt, room enough for anything is abundant and free.
Extreme primitives like us and bacteria, who don't have abundant private energy sources, welcome the low-intensity energy influx from a nearby star. For anybody even mildly sophisticated, the energy is uselessly diffuse. At the same time, it keeps everything at a noisily high temperature that interferes with signal integrity and fine-grained processing.
* It is possible to export or even host consciousness onto a digital medium - we still have no evidence for this
* All or most civilisations ultimately will want to transition entirely into a digital existence - the "entirely" part is important. If even 1% of a K-2 civilisation decided to stay organic, that would still lead to a Dyson swarm with a population approaching trillions.
* Civilisations of this tech level would do a cost benefit analysis and decide that the several orders of magnitude more resources on a star is outweighed by the inconvenience of a gravity well - I don't think orbital rings are that mass or energy intensive to build and run for this to make any sense
* There will be no future use of waste heat or method of disposal that goes beyond simple dispersal - the jury is still out on that, it may be possible to dispose of waste heat directly onto a black hole. If this turns out to be correct, the energy of a star is more than enough to power a sufficiently powerful laser array to create many in the gigatonne range.
There’s galaxies and things in there.
/s (just in case)
This one, for instance, I’ll admit I haven’t clicked through to the article. I’ve long been interested in these voids so I didn’t figure the article would relay any information I wasn’t aware of so I clicked through to see what people here had to say.
Perhaps Dang could get analytics on how many people viewed the comments and how many people clicked through to the article to answer your question.
"an immense, comparatively empty region of space...proposed to be roughly spherical, approximately 2 billion light-years in diameter. As other voids, it is not completely empty but contains the Milky Way, the Local Group, and a larger part of the Laniakea Supercluster. The Milky Way is within a few hundred million light-years of the void's center."
A void has by "working definition" "less than one tenth of the average density of matter abundance that is considered typical for the observable universe."
https://en.wikipedia.org/wiki/Void_(astronomy)
Tracing out how the very earliest structures in the CMB compare with much more recent galaxy filaments (and the voids between the dense filaments) is an interesting area of research, and there will be open questions for many years to come as galaxy surveys at different redshifts produce observational data.
(All the galaxies will be at a lower redshift than the CMB cold spot, and it is a good guess that the CMB cold spot reflects an arrangement of matter much closer to the hot big bang or cosmic inflation than that. Perhaps one day our descendants will be able to examine the cosmic neutrino background to see if it too has a comparable cold spot, and the same with primordial gravitational radiation; alternatively perhaps they will discover that later-time physics distorted the CMB very slightly. The latter hypotheses are in practice much easier to test with observational data, and of course one can exploit the many unknowns in the dark matter and dark energy sectors without colliding with constraints from known physics.)
https://en.wikipedia.org/wiki/CMB_cold_spot
https://news.ycombinator.com/newsguidelines.html
One direction, nothing whatsoever.
The other direction, billions upon billions of galaxies.
Would be neat!
Paints a bleak picture of a civilization in this situation. Great book though.
Thanks !
https://memory-alpha.fandom.com/wiki/The_Void_(region)
https://en.wikipedia.org/wiki/KBC_Void
[0] https://en.wikipedia.org/wiki/Giant_Void
[1] https://en.wikipedia.org/wiki/KBC_Void
[2] https://en.wikipedia.org/wiki/Laniakea_Supercluster
https://www.zmescience.com/space/the-local-void-mapped-04322...
https://en.wikipedia.org/wiki/NGC_6503
Two tiny dwarf galaxies are in the process of leaving the Local Void due to the attraction of the galaxies surrounding it:
https://www.space.com/33748-dwarf-galaxies-escape-cosmic-voi...
The universe will expand so much that civilizations into the VERY distant future will not be able to see other stars and galaxies, and will have no way to know that there's more out there.
It's quite sad actually.
https://en.wikipedia.org/wiki/Local_Void
* 1 megaparsec = 3.26 million light years
How do they know or believe that it doesn't contain dark matter?
Roughly, hot spots have more matter, get hotter as that matter collapses into stars, hot gasses, and eventually black holes; cold spots have less matter, and because of the expansion they get colder, sparser, much bigger, and eventually become practically empty.
Early pockets of dark matter overdensity, similarly roughly, helps turn on the heat very early, and keeps the heat turned on longer than otherwise. Early pockets of dark matter underdensity makes it much harder for stars to light up in the first place.
Generally one simulates the introduction of non-uniformities in this distribution during Cosmic Inflation, and then the overdense areas collapse while the underdense areas experience the cosmological constant. At the time the universe has expanded enough that photons can free-stream (this marks the beginning of the CMB, see [1]) the density-differences in one part of the universe to another are very small, but over billions of years the collapsing dense regions become ever denser (and form stars and galaxies) while sparser regions simply become colder. (Both become emptier, relatively; collapsing a diffuse cloud into a dense cloud leaves behind a lot of space emptier than when the diffuse cloud was populating it).
Dark matter plays a crucial role here, because it collapses more slowly than visible matter by forming haloes and other structures, essentially suspending visible matter (gas) above the cores of galaxy clusters (where in later times you find really gargantuan black holes). It is also important that its underdensities and overdensities after Cosmic Inflation were roughly the same as that of what became the particles of the standard model, and it is this feature that appears to be crucial to structure formation : https://map.gsfc.nasa.gov/universe/bb_cosmo_struct.html
However, once the CMB has formed, those photons no longer interact appreciably with the dark matter of the universe -- the gravitational interaction is weak and gets weaker with the expansion of the universe.
So it is the early distribution of dark matter (before atoms, before protons) that is important in creating CMB cold and hot spots.
It would be odd to have a hot spot become anything but a matter structure (galaxy cluster) because of gravitational collapse. Likewise, it would be odd to have a VERY cold spot become anything but filled with a very sparse gas (e.g. hydrogen + photons + neutrinos). The WMAP Cold Spot is not THAT cold and so could have structures like galaxy clusters in it, but fewer of them than than in the filamentary structures. Indeed, we may live in someone else's cold spot. Galaxy surveys are trying to gather up evidence one way or another for the densities of galaxies and their ages along various lines of sight from here, which will help us determine how well WMAP cold and hot spots line up with galaxies. ALL galaxies are much more recent than the CMB.
Several ideas about how the WMAP Cold Spot could have been a WMAP Average Spot at the time the CMB was formed, but that (mostly new physics) events in the more modern universe present us with a relative cold spot. Some of these have the virtue that these more modern events are more amenable to study with our current level of technology than the distribution of gravitational waves after cosmic inflation and the detailed study of the cosmic neutrino background (which is similar to the cosmic microwave background, and so should have similar small temperature fluctuations; but measuring ultracold neutrinos is not something we can do today, nor can we yet look at the frequencies and amplitudes of primordial gravitational waves, however there may be indirect probes of both...
The https://en.wikipedia.org/wiki/Axis_of_evil_(cosmology) is a pretty curious thing, but I think the safest bet is a combination of randomness and https://en.wikipedia.org/wiki/Pareidolia .