Upper limits on partial Dyson spheres in the Milky Way
arxiv.org
arxiv.org
He didn’t hesitate. He said we need to teach children genetic engineering to children in such a way that they could approach it playfully. Only then would we have a chance of developing warm blooded plants which would be essential for colonizing the asteroid belt.
So, if anyone has any ideas for that…!
"The first species to emerge from a Noah’s Ark egg will be warm-blooded plants designed to collect energy from sunlight and keep themselves warm in a cold environment. “Plants could be engineered to grow greenhouses the way turtles grow shells” The greenhouse would consist of a thick skin providing thermal insulation, with small windows to admit sunlight. Outside the skin would be an array of simple lenses, focusing sunlight through the windows into the interior. Groups of greenhouses could grow together to form extended habitats for other species of plants and animals. In that way, “We will be the machines getting life to grow all over the universe.”
https://en.m.wikipedia.org/wiki/Leaf_window
https://en.m.wikipedia.org/wiki/Mesembryanthemum_crystallinu...
Here’s the Wikipedia on thermogenic plants. I did not know skunk cabbage can melt snow! I used to have it in my back yard. https://en.wikipedia.org/wiki/Thermogenic_plant
Here’s a paper on the genetics and cellular biology of thermogenesis in skunk cabbage:
Assuming perfect efficiency in capturing whatever sunlight they get, perfect conversion to chemical storage (i.e. sugars, or any other fancy molecule with energy-intensive bonds) and a perfect conversion from that to heat. Would there be enough energy to keep the plant warm? Against a temperature difference of 40ºC+?
So, then again, why would you need to warm yourself if you get a warm sun shower perpetually?
I could imagine a plant that walks along the surface to stay in the sunlight.
Maybe lay down roots all over the asteroid to do the refining and have long tethered leaves always in the sun.
If the leaf stalks can grow at the same rate as the asteroid rotation, just keep growing and wrapping the asteroid until you're left with nicely spooled refined materials.
I don't think a hot blooded plant is practical or necessary, but there is enough energy that it could be possible.
Oxygen plants produce would actually be a lifting gas on Venus so pretty doable. Plenty of sunlight and co2 too.
But I hit a wall with the Mack of water in the atmosphere.
I guess you’d just need to provide your own water?
A while ago I posted about it in Reddit:
https://www.reddit.com/r/ColonizeVenus/comments/ku55zg/float...
Great for power generation though!
That doesn't mean soil for any kind of organism is as hard. There are many of them that don't need all that complexity even on our world that doesn't strongly select for it.
Highly recommended.
I think most people "like" the idea because it's so tangible. But that doesn't make it any more or less likely that it actually exists or makes sense.
1. sidestepping thermodynamic laws - to allow massive energy use without detectable waste heat
and/or
2. sidestepping time lags - so that the system does not need to be bunched as closely together as possible to allow for efficient communication and flows of material
And before you can build a full Sphere you have to build a partial Sphere. Which is where stability will really kill you.
Dyson Swarms might be more practical, but you still have a computability problem because you have an insanely huge number of objects in orbit and you somehow have to keep them from colliding with each other.
Not so much a three body problem as an n body problem. With a built-in light lag delay of (at least) minutes.
I'm not sure if anyone has modelled that, but it would be hilarious if the computing and station-keeping power requirements turned out to be a significant proportion of the available energy,
Wait, what? You can't have a spherical constellation of unconnected stuff that mostly stays in place, that's not how orbits work. You can have a single orbital ring, but a sphere consisting of many circular orbits would have these orbits intersect with very large relative movement. If you're thinking about non-rotating constellation where the gravitational pull is balanced by solar wind, the problem is that they have gravitational interaction with each other and the planets so it's inherently unstable, they would "want to clump up" and as soon as they do, the balance is disrupted as the same mass has less solar pressure and it starts to fall into the sun.
Why would a device that has 1kW/m2 at its disposal at all times, be fundamentally unable to counteract gravitational interactions? We are not talking about planetary gravity wells here but much weaker ones.
There could very well be individual dyson swarms out there and we haven’t seen them or haven’t realized that’s what they are. But building them around every star in the galaxy is something I’ll never understand why it’s taken as a given.
Unless such a civilisation can dump the waste heat as something other than infrared light or send that waste to somewhere other than the visible universe, it’s still extremely visible.
Freeman Dyson never proposed building anything even vaguely like what is called a Dyson Sphere, and was famously irritated at having it attributed to him.
https://www.inverse.com/science/how-many-dyson-spheres-are-i...
I remember some discussion of this point in his autobiography. He wasn't talking about the Star Trek version, but certainly the intercept-all-the-sunlight constructions we're talking about.
All of this is obvious to anyone who does the math.
Obviously the rotation of the star has no effect. But the need to move between habitats precludes substantial differences in orbital plane (look up orbital plane maneuver, these take exceptionally large delta-V), keeping things close to the ecliptic.
Doing the math produces a picture very different from what you imagine.
Even if the cities do cluster in one plane, that doesn't imply the power stations will.
I'm glad you liked Energia though.
I’m always very open to the idea that there could be a lot of physics we don’t understand yet. We could be at 0.1% of an understanding of the basic laws of the universe. I’m not saying I think that is likely or unlikely, but I do think it is possible.
In 1822 the Chappe optical telegraph had been in use since the Revolution, and the electric telegraph was ~20 years away. You'd have had to be singularly unimaginative not to envision an eventual extension to instantaneous voice.
Also the issues of dyson spheres aren't that bad. they could for instance channel the heat loss energy in a narrow beam out of the galactic plane so at least they'd be hard to spot by other galactic observers.
If we don't assume any new physics and / or thermodynamics, then that constrains the discussion a lot. We have two basic ways of generating a lot of power, fission and fusion.
Fission uses fissile materials, which are relatively rare, not just on Earth, but in the Universe at large. There's plenty enough for us at our current energy generation needs, but not nearly enough for a galaxy spanning civilization. That leaves us with fusion.
Fusion reactors, as currently conceived use Helium-3 or something like that. There's enough of that around the solar system to power a civilization for a long time, even though the mass of oddball elements like Helium-3 make up a very tiny fraction of the total mass of the solar system (which is mostly the Sun with a smidgen of Jupiter).
Most of the solar system's mass is plain hydrogen: one proton and one electron.
Is it possible to fuse most / all of this mass in the solar system? Yes. We won't go into the details, but trying to fuse regular hydrogen (regular protons) together is highly impractical outside of the core of a star. Preferably a red dwarf type star which can more completely burn its fuel than our own Sun will, and live a lot longer to boot (a trillion years vs. ~10 billion for the Sun).
So now we're talking about some kind of solar collectors, and if you want to collect _all_ the energy from a star, you want a sphere of some sort. Or a swarm of objects in orbit achieving the same effect.
Hence Dyson sphere / swarm.
For what? What are you doing with it? Not to forget the fact that all energy used eventually turns into heat. All of it (with the exception of electrochemical transformations). You're bringing all of that into Earth you're cooking everybody alive.
How are you bringing that energy from the sphere to (wherever place)?
Putting solar panels on Earth itself works much better. Heck, make a Dyson sphere on Earth (facing outside), that makes more sense.
So in the best case scenario, you are powering computronium, upon which trillions of sophonts live out their digital lives. Hopefully doing some science, or at least playing some interesting games. A vast distributed network.
In the worst case scenario, Blockchain and spam emails.
Either way, people will put that energy to use.
With a Dyson swarm, energy is received on the inside, towards the star, and heat is radiated outward. Lower power systems can run off the heat radiation of the inner swarm similarly. It is all eventually released as very low level heat, but diffused across the entire outer surface of the swarm. No hotspots... because someone would come along and use it.
The Earth would also likely be deconstructed by this time, so don't worry about the biosphere, there won't be any.
One example: powering lasers for light sail ships to colonize other star systems.
Light sails are "theoretically" possible but you don't need that much energy to push something that's feasible to push.
Or better, there's a better source of light radiation: the sun itself. No need for a laser, just use a focusing mirror and you can have 100x more pressure than just from the sun itself.
https://www.planetary.org/articles/lightsail-2-successful-fl...
Light from the Sun isn't coherent, and you can't focus it with mirrors very far away. Lasers have many orders of magnitude less divergence when talking about distances measured in light-years.
To expand on your point, those characteristics become even more important when using the light received to decelerate at your destination, though it is worth noting that there are alternative means of deceleration that don't have the same requirements (eg. electric and magnetic sails).
As the other poster mentioned, harnessing the sun's energy and turning it into a better form suited for light sails is the way to go. Sailing on the solar wind within a star system is a different tech with a different purpose.
I’m missing something here, because even if we decided to build a Dyson swarm of course we are going to start with putting solar on and around Earth because this is where all the stuff we care about is.
That’s just the first step in a journey of a miles miles. (TIL where that quote comes from: https://en.wikipedia.org/wiki/A_journey_of_a_thousand_miles_...).
This seems so obviously it can’t be what you’re taking about though.
Would it not surprise you that fusion in general has been studied extensively by physicists for nearly a century? It takes very high temperatures, pressures and quantum tunneling to get two protons to fuse.
Here's some reading to get you started:
https://courses.lumenlearning.com/physics/chapter/32-5-fusio...
Or read about how the Large Hadron Collider works.
What I'm saying is it's too soon to say what's possible with fusion and what isn't. We don't even have a break even reactor yet. We can even say for certain that we ever will.
I'd give your criticism some consideration if I thought you had even the slightest knowledge of what we're talking about.
Let's talk about the core of the Sun, where p-p fusion takes place. Remember, I said at the top: no new physics.
The core of the Sun is hot, like really, really hot. How hot? 15 million Kelvin. So no solid material ... made of atoms ... can be anywhere close by because it would vaporize. You can talk about active cooling or whatever, and that's not going to help. But let's assume we have some magical material that can deal with that temperature, and keep going.
We're going to skip the pressure that really hot plasma is under, and assume we have terrifically awesome magnetic confinement that can handle that. We don't actually, but let's move on.
The other problem with 15 million K is that all that energy wants to radiate away. Yes, you want to absorb some of that radiation (hard gamma, by the way, very nasty) as part of the energy generation process, but if you let the plasma cool off, the reaction rate drops. "Cool" in this context is relative, at 7 million K, the reaction rate is very close to zero.
The last problem we will talk about today is volume. The above conditions get us a fusion power density of... 276 watts / cubic meter. To have a fusion plant that generates 1GW of power, we'd need to contain a cube 153 meters on a side of 15 million Kelvin plasma.
Oh, wait, that assumes the magnetic containment and everything else requires zero power to run. So we'll have to go bigger, much bigger.
Are you starting to understand the scale of the problem... trying to design a proton - proton fusion reactor?
I am not the arrogant one, I'm just listening to the fusion scientists who have been studying how all this works.
> We don't even have a break even reactor yet. We can even say for certain that we ever will.
And here you are expressing doubt that we'll achieve even the easiest kind of fusion reactor. We have achieved fusion, just to be clear. We can reach the temperatures and pressures to see some reactions.
Assuming civilization does not collapse (climate change, war, etc) we will be able to engineer a fusion reactor that is some kind of practical.
But it won't be proton-proton.
But the scaling issue doesn't go away unless you go with even higher temperatures and pressures.
Doesn't sound like an arrogant person to me...
FYI I understand how magnetic confinement fusion works at a high-level, as a non-scientist.
There's a lot of assumptions you're making here. First that we need hydrogen-hydrogen fusion. Many current reactor designs use deuterium and tritium (nasty stuff tritium.) It doesn't have to be plain hydrogen, it just has to be elements common enough that we won't run out (or that we can breed using neutrons - that gamma radiation you talk about - from the fusion reactor.) Some designs are more exotic with fuel using isotopes of helium, lithium, boron. Second many current reactor designs use a plasma temperature well above 15M K. I've heard of 100M K and that's not an upper limit.
But you're also making assumptions about the volume of a reactor - we don't even know if magnetic confinement fusion will end up being the best design, but if we assume it does - then stronger magnetic fields really decrease the volume required. In fact development of stronger magnets based on high-temperature superconductors may be the biggest breakthrough in fusion research in the last decade - see https://news.mit.edu/2021/MIT-CFS-major-advance-toward-fusio...
> And here you are expressing doubt that we'll achieve even the easiest kind of fusion reactor.
We don't have a break-even reactor yet by the way - we have achieved fusion for short periods of time and by putting in far more energy than could be produced. That milestone is probably still at least a decade away.
My point again is that we don't know enough to be able to say what's possible and what isn't. History is littered with people arrogant enough to say what we can never achieve and humans keep surprising. Sometimes even things that seem impossible - like detecting planets around other stars when the physics of optics is very clear that an optical telescope could never directly image a planet in another solar system. That was wrong on two fronts, one it doesn't account for gravitational lensing, and two it didn't account that we might cheat and detect planets indirectly. And so the arrogant people were wrong again. Don't make that mistake.
I think there are more. Like radiation from evaporating black holes.
Evaporating black holes?
Yes, if you are willing to wait a very, very long time, and have collectors over a large area.
However, if you want to get stuff done before your protons evaporate, you could instead throw matter into a black hole, thus increasing its mass. The radiation given off by the accretion disc is substantial, and can be collected... over a large area.
IIRC, the mass-to-energy efficiency is something like 40%, which is really good.
They are a little difficult to set up however...
That is an interesting prospect, with a very high mass-to-energy efficiency. Of course it requires careful management of inflowing matter. And you can shut if down if needed by stopping the inflow, assuming you have enough stored energy to recreate the micro black hole sometime later.
Good channel too.
Not a chance. I disagree 100%. The materials science and orbital mechanics for coordination alone are way beyond our capabilities.
N-body problem instances are never undecidable in the automata-theory sense; you can answer any question about the future trajectory from given initial conditions straightforwardly, if slowly, with interval arithmetic. The question of whether initial conditions exist that evolve to a given result is undecidable, but as with undecidability results in general, we do not need to decide it in order to build a working system, only to prove the optimality of a given program.
You seem to be making up reasons to justify a preselected conclusion without bothering to think about whether they are true or relevant or not, and I wish you would not do that.
You could use a smaller or larger radius, resulting in higher or lower irradiance and higher or lower orbiter density, but we have a lot of experience with different kinds of solar panels at 1 AU, so we know it will work.
No, there's no problem with orbital dynamics, control, computation, communication, or any of that nonsense. 50 years ago those were potentially challenging problems, but not now. Today the only remaining obstacles for a Dyson sphere are manufacturing and politics.
With really thin sails (0.78 g/m^2) they don't even need to orbit, as they can use light pressure to compensate for gravity (what Robert Forward termed a 'statite'). The light they reflect hits other sails on the other side, but this isn't a problem if they are distributed uniformly.
I think the answer may be that most civilizations never need or want to colonize everything in sight. It could also be political: no species gets to the level of being able to build structures like this without breaking up into competing polities. We think about colonizing everything because we’re still in the mode of a creature who evolved on a planet and spread out everywhere.
It’s probably the case that with fusion dyson swarms aren’t used due to the opportunity cost of building them. In 1-200 years we’ll find the idea of surrounding the sun with metal as laughable as there being canals on Mars.
Speculation what form future tech takes should have be broad and uncommitted.
* Given our current knowledge, Dyson Spheres are essentially impossible (just lesser-known point is that unlike planet, full Dyson Sphere or Ring World would not be attracted to the star that it would be built around, so it would have to be guided to move with it - see Larry Niven's Ring World Engineers). * What a civilization would do with all the energy, whether it would want it, etc are other unknowns.
As you say, turning one person's clever idea into a whole research program at the very least neglects other great scifi novels.
Thermodynamics does not play around.
and the dark matter is everywhere (almost, there're galaxies without it) which would mean that most of the universe has intelligent life but then why there's no other signals? something should've leaked/pointed at it
Any sort of Dyson-spherish thing would radiate in infrared, and not be dark at all. A long time ago somebody went looking for these infrared emitters, and found billions (and billions) of them in our galaxy alone. Turns out low-grade infrared-emitting stars and star-like things are more common than dirt. There is no way to tell them apart from a hypothetical Dyson thingy, even if there were any actual reason ever to build one of those. (Which, hint, there isn't.)
"The observational signatures of such “Dyson spheres” include waste-heat from the absorbing sphere, obscured direct star light (resulting in both an apparently underluminous star and potential temporal variations in brightness) and the effects of feedback on the properties of the star from the surrounding sphere."
So there are ways to distinguish probable Dyson spheres from the majority of these natural infrared sources.
You might imagine a playful civilization building one next-system-over to fool planet-bound hicks who actually still believe they are a good idea. The hicks restructure their whole civilization to be able to mount a trip to visit it, and when they arrive find it is all just a mock-up.
EDIT: but I like your idea, sounds like it would be a fun short story!
Dyson was writing at a time before people were thinking about controlled fusion as a way to generate power. Furthermore, he projected not building, but growing a biosphere spread out around a star. The notion of constructing a thing to try to gather and convert all of a star's radiation is a radical corruption of his idea.
Finally, he posited this development in the near term, while humanity remains far short of any capability that could actually be called advanced, with nothing better to hand than genetic engineering and dumb rockets.
Let's presume that the universe is full of Dyson Spheres, and the gravity they produce is what we call "Dark Matter". Well, Dyson Spheres must be built, right? So earlier in time, there would be fewer of them, and later in time there would be more of them.
When we look into the sky, we look back in time. So if this were the case, when we look backwards in time we should see more brightness and less dark matter effects, while closer in time we should see less brightness and more dark matter effects.
We do not see those patterns. Dark matter is consistent over time, as far as we can tell, and brightness from stars remains what we would expect.
Jokes aside, is there really any practical value in this sort of research, or is it the kind of thing that we do because it's interesting and kinda cool? Don't get me wrong, I think it's valuable for that alone, but...
In many ways it is too early to do this research, so it is a kind of art (as is a lot of research, imho). As long as only a few people do it, it's cool and useful so we can be aware of our potential future.
On the other hand, since we have no credible evidence of extraterrestrials, it would be surprising to find a civilisation so advanced to build a Dyson sphere. If they can build Dyson spheres, wouldn't they already be all over the place?
Ok, I suppose I should actually go read the paper now...
Would such a civilization spread to more than one star is actually also a question, or would they control their population rationally stay on their Dyson sphere and only start to move when the star had less than 100,000 years left to go.
Only some Dyson sphere variants, like Shkadov thrusters, are primarily conceived as ways to move around. Which personally seems to me less likely, is a civilization, as well as the ability to construct these objects, also going to have a species level interest in going exploring?
Check your math: this galaxy is ~10^5 light-years in size and ~10^10 years in age.
1. Not control their population for some reason.
2. Had some sort of interest in exploring.
3. Implicit also in the speed of light thing, would find it really interesting to send a portion of their population to the next available and suitable star which might be enough light years away to make communication impractical. I mean for our civilization there is some level of argument that says it would be a ridiculous idea to move to a new solar system and we have an intellectual exploratory streak in our species.
I mean we are currently not at the level of being able to do a Dyson sphere, it took us 4.543 billion years (age of earth) to get to the part that somebody could conceive of it. There is also some discussion as to whether or not our civilization is going to last, so given that and the other things I said it seems unlikely to me that any Dyson sphere civilization would actually build more than one, but maybe some build two because binary stars or some other weird circumstance which makes it worthwhile to do.
on edit: if we get to Dyson sphere building capabilities which seems really unlikely, will we build more than one? How many more?
So again, still haven't heard any argument why an alien civilization achieving the ability to build Dyson spheres, even if they did so far enough in the past that they would then have adequate time to traverse the galaxy afterwards, would then have to be everywhere?
yes, there is, if the achievement of Dyson sphere building happened long enough in the past for there to have been sufficient time. 50,000 years ago even, no. The length of human civilization is 6000 years approximately, what if this civilization much, much older than ours 6000 years ago just started building it's first Dyson sphere. For some reason the assumption is that it was far enough in the past that they COULD be everywhere if they wanted to.
But then the phrasing is not that they could be everywhere but rather they would be everywhere, hence no civilization has built Dyson spheres. A lot of this theory that the aliens will go about building lots and lots of Dyson spheres seems based on the assumption that they will be a lot like us, but actually I don't even think we would ever build more than one. If we built a Dyson sphere it would be because we were at the point we needed the energy and we had the technology to do it of course, and we had a political system that could harness everyone to do it. But once we had the Dyson sphere I am not sure we would ever be at the position were we would need another one. Since people tend to have fewer kids the higher their standard of living it may be that with the standard of living of Dyson sphere civ that our population would be at replacement level, that is to say we would never need to move from one Dyson sphere until the sun was just about used up.
So again, sure there is sufficient time with waves of colonization (started far enough in the past) - but waves of colonization assumes a species that has a colonization urge and perhaps one that has a colonization urge greater than that of humanity. That's a pretty big if, considering all the other big ifs in the whole building a Dyson sphere scenario.
Galactic orbits are far more chaotic than the sedate stable orbits within the solar system - stars closely approach each other on a somewhat regular basis.
They’re crappy computing devices. Even if you figured out how to program one — and that’s an “if” that would make Sagittarius A* look like a neutrino — there’s no way to read the information out except Hawking Radiation, and that would take 10^70 years.
https://youtu.be/0GLgZvTCbaA (8:36)
I figure they'd have to be.
They'd need more than a solar system's worth of raw resources to build the sphere. They may need more than a solar system's worth of resources just to build the tools and craft to be able to build the sphere. They're going to need an insane amount of production facilities for various components, and that's going to take a massive amount of resources. That's going to require exploring quite a bit of a galaxy.
The number I’ve seen quoted is 50M years to colonize the galaxy: http://www.sentientdevelopments.com/2012/01/new-mathematical...
> they calculated that any galactic empire would have spread outwards from its home planet at about 0.25% of the speed of light. The result is that after 50m years it would extend over 130,000 light years, with zealous colonisers moving in a relatively uniform cloud and more reticent ones protruding from a central blob. Since the Milky Way is estimated to be 100,000-120,000 light years across, outposts would be sprinkled throughout the galaxy, even if the home planet were, like Earth, located on the periphery.
It’s actually so fast that advanced civilizations would have had time to colonize the galaxy and go extinct many times over without us noticing.
Or maybe their spheres were built so long ago they’ve already collapsed and been consumed by the stars again.
It’s a great mystery and interesting thought experiment though.
Our ancestors from 50M years ago are all extinct. So a civilisation spreading through the galaxy would have evolved in all kinds of different ways. It's not obvious to me that these diverse evolutionary strands would all still be interested in Dyson spheres, or space travel, or even astronomy.
There's a belief that's hard to shake off, that the properties humans have that we think most important represent some kind of evolutionary pinnacle. Typically, those properties are language, and a large brain for processing language. But if language and a large brain are really such great evolutionary advantages, why are humans the only creatures on Earth that have evolved those properties? Possibly language and a large brain are an evolutionary backwater.
At 0.25% of the speed of light, it would take us 1,600 years to reach Proxima Centauri; but it might take a lot longer to reach a star with habitable planets. We'd definitely need generation ships. After (say) a million years, we'd presumably have evolved to adapt to life on generation ships. It's not obvious to me that such adaptations would leave us fit to inhabit a planet. And perhaps adaptation to life on a generation ship means adapting to eating your fellow passengers.
Given the history of humanity, I find it hard to believe that the population of a generation ship could survive as long as 100 years without war breaking out on-board. We've had large brains and language for about 50,000 years, as far as I can tell; we've been warring the whole time. Maybe large brains and language pre-dispose us to war? If that's right, then it seems unlikely that intelligent life would ever spread far from it's planet of origin.
I'm very sceptical of the idea that any "civilisation" could ever spread far from its home planet. There are two things that we refeer to as a civilisation: a culture, and a species. Culture changes very quickly - over a single lifetime. But on a scale of millions of years, speciation is also pretty quick. So I can't see how any kind of homogenous civilisation or species could spread through a galaxy. They would have diversified before the train even reached its first stop.
So I don't have any insurance against being kidnapped by aliens.
Only two minor nits:
> why are humans the only creatures on Earth that have evolved those properties? Possibly language and a large brain are an evolutionary backwater.
Nearly every animal has language, for cooperation, competition, raising their young or to find a mate. Bees, whales, primates, birds, etc. all communicate strategically with some type of language.
> Given the history of humanity, I find it hard to believe that the population of a generation ship could survive as long as 100 years without war breaking out on-board. We've had large brains and language for about 50,000 years, as far as I can tell; we've been warring the whole time.
There’s been war somewhere the whole time, but not everywhere. Costa Rica, Iceland, Panama and several minor countries have no military: https://en.m.wikipedia.org/wiki/List_of_countries_without_ar...
It’s possible to find many countries who have not fought wars in the past 100 years. If you look more narrowly it’s possible to find communities unaffected by local war in hundreds or maybe even thousands of years (in other words, they fought a war but did so by traveling great distances, not fighting each other).
A ship would be much more like a tiny, isolated island colony rather than the geopolitical tensions that dominate the news.
Finally, wars rarely result in the extinction of both sides. Even if there was a large scale conflict it would likely be resolved prior to social collapse. There would be little incentive to kill so many of your fellow crew to the point where you’re putting every survivor at risk.
> Nearly every animal has language, for cooperation, competition, raising their young or to find a mate. Bees, whales, primates, birds, etc. all communicate strategically with some type of language.
There is currently only one species on Earth capable of even imagining the things being discussed here. On the other hand, it seems there may well have been more, but the others are now extinct.
One of these issues only we are discussing is the evolutionary viability of those abilities, and the fact we can do so suggests that it is, to some extent, up to us whether or not they will be.
Yes, I elided that bit, in the aim of brevity. I think there is a difference between human language and animal languages, in that human language is "creative" - we can freely create new utterances with new meanings, and expect to be understood. We know this of human language, but I would be very interested to learn of evidence of it in other species (chimps come close).
But I think the cones thing is still interesting; it means that for any given maximum travel speed, there must be other civilisations that can never know anything about you, nor you about them.
There is no need for all, or even most, of the civilizational variants to retain those characteristics. As long as some variants do, civilization would continue its inexorable interstellar spread, it would just end up being lumpy rather than a relatively even wavefront.
Indeed, survivorship bias would seemingly tend to conserve the required characteristics and possibly start constraining the ways in which civilizational offshoots can vary. And it isn't hard to imagine stay-at-home variants succumbing to the influence of later arriving spreader variants to become spreaders once more.
Once it is done, possibly much much much later, somebody may stumble upon it and use it in some creative (and unforseen) ways for other research.
On the other hand if you give any probability to alien existence, then this is very much practical already in the search for them.
Also I think science works the way that you use your fantasy to come up with outlandish things, and then try to rule them out with logic.
It's difficult to imagine a discovery that would have more practical import than the discovery of an extraterrestrial civilization.
But anyway looking for Dyson spheres will not reveal any extraterrestrial civilizations.
To make the point, literally nothing can be classified as "discovered" under your rules because any alien civilization may know about everything we'll ever find or figure out, and if they know about it we can't have discovered it.
Columbus was a murderer and people in America before he got there deserved way better but this type of nitpicking correction is just noise if you don't even say what is a more appropriate phrase.
Why, yes, of course - even in the immediate short term the ships returned from expeditions with gold and slaves; and from the very start the exploration voyages were planned and funded solely as a practical endeavor for trade and looting, not as an intellectual curiosity.
The signal this would create to an outside observer I think would significantly change the heat signature and periodic changes, depending on our observation angle to the star.
It gets converted into other kinds of energy, and eventually becomes waste energy, ending up as low-grade heat. Hence the search for infra-red sources. But the amount of energy that a Dyson sphere absorbs must be equal to the amount of low-grade heat it radiates; so I'd expect a Dyson sphere to be very bright in infra-red - much brighter than brown or red dwarfs.
Such an object should be quite easy to spot.
Any advanced form of civilization that can build one, probably figured how to do fusion efficiently locally and doesn't have to build these insanely inefficient energy harversters.
Keep in mind that the sun is very inefficient at energy release.
Dyson sphere prediction is like predictions in the 1800s how we would have coal and steam powered airships to travel around.
The reality is that steam via coal fire is too inefficient. Coal is just too heavy. Jet fuel is much more efficient/energy dense and not need to build giant airships.
Same with any advanced civilization. Dyson spheres just don't make sense, but they sure make good sci-fi movies/stories for the gullible.
The likeliest case for a Dyson Sphere civilization would be some sort of solar powered Gray Goo von Neumann replicator.
To reproduce such heavier elements in fusion reactors on earth would require, likely, a much higher energy than the output.
Also: the Pacific, Atlantic, Indian, and Arctic oceans are made of water, which has hydrogen in it. Also all of the Antarctic and Greenland ice, the Great Lakes, Caspian Sea, Lake Baikal, and Lake Victoria.
Most likely you would use up Neptune first, and save Jupiter for later.
The view that they wouldn't do both is premised on the assumption that they won't need or want that much energy, combined with the assumption that the problem of disposing of the waste heat makes the extra energy not worthwhile.
"Why buy the loaf when you get free slices?"
He speaks to the subject in this excellent interview playlist, link is to the specific Dyson Sphere part:
https://www.youtube.com/watch?v=GPB775_BZlw&list=PLVV0r6CmEs...
"Any sufficiently advanced technology is indistinguishable from magic."
I'm not clear what is meant by "inefficient at energy release". Does that mean that the in the process of energy release, some of the energy is converted into heat? I.e., more energy?
What if the external shield of the sphere would be artificially heated to 4000K or higher ? Completely invisible.
If you happened to live in a planetary system without adequate gas giants, you could probably find some way to scoop mass off the surface of your star or capture it from coronal mass ejections, then use fusion to transmute it into the materials you need. Even Sun is 1.90e30 kg, and it's rather small as stars go.
1. "Stellar husbandry". That phrase alone is worth the price of admission.
2. The idea of doing mass spectrometry on a jet of matter coming out of a star to separate it out into streams of hydrogen, deuterium, helium, etc.
3. The idea of creating artificial gas giants as a storage mechanism.
(The list goes on, but 3 is a magic number.)
Isaac Arthur's youtube channel goes into this in some depth (and is generally excellent, IMO). Here's an episode on Dyson Spheres:
But there is also the Dyson swarm, which is like a starlink constellation orbiting a star and designed to collect as much energy as possible.
Anyway I don't know the answer to your question, but if we ignore structural problems with a sphere we could imagine a material a few atoms thick, like a giant carbon nanotube structure. Then one wonders how much material there is in Jupiter as an approximation of total matter in the solar system. I will leave the calculation as an exercise to the reader. ;)
Per the Ringworld not being stable, I think the same math applies to the sphere as well as the Ring, so the sphere will need attitude jets to maintain position with respect to the central sun.
Dyson swarms seem drastically easier to construct. We could build one example of that habitat fairly soon!
plenty of material to capture the surface
+ you don't need a sphere, a ring/few rings would be enough
Judging the dynamics of technological societies by those of evolving organisms is a common and extremely misleading trap.
More specifically, anybody sophisticated enough would dismantle their local gas giant and ice planets and convert them directly to energy, and leave the local daystar entirely out of the transaction.
An advanced civilization will exist almost exclusively in the far outer reaches of a solar system, where the daystar provides nothing more than gravitation to keep the Kuiper belt organized. The most valuable resource for this advanced civilization will not be energy, which is cheap, or materials, which are cheaper, but cold. The abundunt cold out in the Kuiper Belt is essential to not being vaporized by the waste heat of the high energy processes more or less advanced civilizations cannot resist indulging in.
agreed that cooling might be something to look for therefore outer reaches are very tempting but then how do you deliver energy there?
We’re running out of excuses. We’re either alone, or we’re effectively alone ie everyone else is forever undetectable. Meaning they’re more primitive, or stuck in some subterranean ocean or something. Either way, we’re the Ancients sci-fi stories ale we ya talk about.
Native tribes could be forgiven for assuming they were alone until explorers and conquistadors arrived.
It’s possible that a civilization millions (or billions) of years ahead of us in biology, energy, philosophy, etc. is just beyond our comprehension at this moment to even know what to look for, where or how.
Plus, we already try to make things hard to find like stealth fighters. Perhaps it’s a good idea for survival in the universe to be difficult to find.
Even if you skip past that to the underlying dark forest idea, it’s an argument based on pure faith with zero evidence to support it. You need an all power malevolent society that works on a time scale of thousands if not millions of years, and then nit only eliminates another society for “reasons”, but also then also perfectly covers up its own existence, because there may be some other bigger bad out there. It’s about as convincing as the unicorn that’s always right behind you, but everyone ignores because unicorns are super dangerous.
They are well worth the read, IMO.
That assumes we would even be able to recognize one if we could see it.
Even if I wanted to be generous, “really big” and “no reason why we would necessarily be able to see any of them” is indistinguishable from my statement of being “effectively alone”.
Also agreeing with one of the comments above about how mind bogglingly massive space is, we've been effectively "listening" to space for only about 100 years, which creates an effective "listening sphere" of 4.188×10E6 light years^3, or 0.000524% of the milkyway's EIGHT TRILLION cubic lightyears in size (even if we could listen to all directions simultaneously, which we can't!)
I mean, we've been listening to the Wow! area for 50 years now, which also hampers the kind of electromagnetic 'sweep' we could possible be doing in the meanwhile.
My overall opinion is that it's just simple not been enough time of listening.
Actually this idea seems quite interesting, it would be cool to do the calculus to figure out our effective "increase" in contact intersection as each consective second, minute, hour, day, and year goes by as we "listen" to space. Infinite overlapping spheres in an infinite 3D space... hmmmm
The reasons why they listen to the hydrogen line is because it’s the most easiest to detect. However, the 50 year timeframe isn’t really a problem. The entire sky has been measured multiple times in this 50 years, and nothing has been found. Unless you believe the signals passed 51 years ago, then the silence is deafening.