Blackhole starlifting makes more sense to me than Dyson spheres (see section on star lifting): https://arxiv.org/abs/1104.4362
> Importantly, researchers have concluded that a thin accretion disk around a rotating black hole is the most efficient power source in the universe , a process up to ~50 times more efficient than nuclear fusion occurring in stars (e.g. Thorne 1974; Narayan and Quataert 2005). If any civilization is to climb the Kardashev scale, it would certainly at some point want to master that energetic source. We call such an endeavor black hole star lifting
Instead of a Dyson sphere, you're using a black hole (and apparent mastery of gravity) to leech energy directly from the sun.
One can't get to the most efficient energy source without bootstrapping. And dyson swarms may be one of the easier ways to get there. I like this video [1] that explains this pretty well, from dyson swarms to kugelblitz. I do not understand enough from the paper to know the difference between kugelblitz and black hole star lifting though.
As a really crazy thought, is it be possible that networks of Dyson Spheres throughout the universe would explain the lower level of visible matter vs the gravity we observe? That is, Dyson Spheres obfuscating their contained stars as an explanation for dark matter?
Similarly, the heat would still escape from them. Could that explain the CMB?
(I expect that I'm way off the mark, but if nothing else it could make for an interesting premise for some sci-fi.)
> Dyson Spheres obfuscating their contained stars as an explanation for dark matter
No - MACHOs have been pretty well ruled out by now. "Several groups have searched for MACHOs by searching for the microlensing amplification of light. These groups have ruled out dark matter being explained by MACHOs with mass in the range 1×10−8 solar masses (0.3 lunar masses) to 100 solar masses" (https://en.wikipedia.org/wiki/Massive_compact_halo_object)
> Similarly, the heat would still escape from them. Could that explain the CMB?
The CMB comes from everywhere at once, uniformly, all the dark spaces in between stars is glowing. Dyson spheres radiating heat would just look like a bunch of dots glowing in the infrared. I don't see how any number of Dyson spheres radiating heat could produce a continuous, uniform field.
Ya know, gravitational lensing and the relative uniformity of the CMB are such succinct and (in retrospect) obvious debunking of those ideas that I almost feel embarrassed to have suggested them. :P
No, the star would heat the Dyson sphere, and it would be observable in infrared. Plus you would need several Dyson spheres for each 'naked' star to explain dark matter and they need to be build at a constant ratio of start to galaxies for all galaxies we observe.
If "By far most of the solar system's mass is in the Sun itself: somewhere between 99.8 and 99.9 percent", then I can't help but wonder if there is enough matter to cover the sun's surface area to create a real Dyson sphere. Where would this matter come from? Is there enough matter in left in the 0.1% (shared by the rest of the solar system) to completely engulf the sun?
I was curious about your idea, so I whipped up some numbers in Python. A 1-meter thick spherical shell at 1 AU from our sun would be 0.02% of the volume of the Sun, or 260x the volume of the Earth. If you go down to 1-mm thick, you only need 0.26 Earths. :)
All the energy the star produces has to escape into space somehow. The way it does this is by heating up the sphere until it radiates out into space at the same rate at which the star irradiates the sphere. The bigger the sphere, the cooler it is, because it has more surface area to radiate away heat.
So if your sphere is too small, it may end up glowing at red heat, which might make it difficult to live on.
You can't assume that they can build a Dyson sphere while their technology is as limited as us earthlings.
If you can imagine some alien species building a mega structure in such a short time, you should be able to imagine that they have a way to transfer and store that amount of energy.
The laws of thermodynamics, as we know it, prevents 100% efficiency in doing that, but if they have a directional heat dissipation device, and their generator is highly efficient, we will hardly have any chance to detect that.
I can imagine they could have some version of our power plant, only orders of magnitude more advanced. Instead of moving electrons, they could be generating and moving matter anti-matter stuffs.
A Dyson sphere _is_ a swarm. Though Jason Wright explains (in jasoncrawford's link) that a spherical swarm is very unlikely in this case. A ring swarm could work, though (he rates it as "unclear plausibility").
The sun is quite dense. I have to think a Dyson sphere surrounding it could be as thin as, say, an onion's outer layer when compared to the onion itself. (Assuming enough distance from the sun to avoid burning up.)
Somewhat true, but it still seems to me that the only way to build a proper Dyson sphere would be to not only achieve scientific breakthroughs that allow for interstellar travel, but to do so in a way that allows us to be able to ferry as much matter from other stellar systems as we need.
I think the most practical approach would be to build something like a buuthandi from schlock mercenary. Of course, even that would contain a staggering amount of matter.
A cloud of circumstellar material could be the explanation but no simple cloud model can explain the strange transit ingress and duration that has been observed.
It's 1480 light-years away; if any construction occurred there, it was ongoing in 536 AD. For reference, this was during the First Gothic War (Belisarius' reconquest of Italy); if the Battle of Mount Badon (somewhere between 482 and 500 AD) actually occurred, it would have been in living memory...
A trap for what exactly? By the time your society can do this to a star, you're not exactly fighting others for resources. You're very much into post-scarcity territory and the traditional motivations for conflict are long gone. I never understood the scarcity mentality we apply to hypothetical super-advanced civilizations. This is like expecting Jesus to take your wallet or the Buddha to kick you down the stairs.
If there are other advanced societies out there I seriously doubt war is their main motivator in space exploration, the same way Voyager and Curiosity are unarmed. Sure, that makes for fun sci-fi stories, but real life is governed by fairly simplistic game theory rules, at least from a high-level perspective. The motivators we have been given through evolution will be the motivators they have as well. Unless we're dismissing evolution as only a local phenomenon, we should expect similar beings to ourselves. I think the 'hostile alien' scenario shouldn't be our default. Sadly, that approach sells ad impressions and schlocky futurist books and influences a lot of people to believe things that are pretty questionable.
If we discovered a primitive species in the European seas we'd be tripping over ourselves to preserve them and study them and to make sure they never, ever get hurt by us (or a stray asteroid or anything we could prevent). We wouldn't be conquering them with robot subs for their pretty coral jewellery or sub-surface oil or whatever. We have enough pretty things and energy here on Earth and in unihabited places if need be. Life is rare enough that we don't need to attack other life for resources, assuming we ever find any.
Haven't atrocious things been done during "exploration" on Earth, e.g. European imperialism and colonization? I'd like to think humanity has moved past that, but there currently seem to be enough war torn areas to show otherwise...
European imperialism and colonization was pretty much not done in a post-scarcity area: we [1] needed all these resources so we took them. There were also ideological reasons involved in colonization ("I repeat, that the superior races have a right because they have a duty. They have the duty to civilize the inferior races" [2]).
Humanity still very much depends on various resources today: fossil fuels, uranium, metals, fish stocks, etc. So wars over resources still very much exist. The sense of "duty to civilize the inferior races" is also alive and maybe even stronger than ever, though expressed with less offensive words.
I would expect a civilization sufficiently advanced to build a Dyson sphere to have reached some sort of sustainability with regard to resources. But what about ideology? What if they deem us barbarians that need to be civilized?
I would argue that the political/race/religious reasons are just cultural cover for resource stealing. Example, Russia just stole Crimea because a warm weather port is a rare resource in their region and benefits their various military strategies. Everything about "history justifies it," "Ukrainian Nazis were planning on killing everyone," and "they wanted us to liberate them" is propaganda.
Once you are post-scarcity, this kind of propaganda will be much less effective. It'll be more obvious its bullshit.
Interesting points. But while such a civilization would be energy rich, wouldn't planets in the habitable zone still be scarce? There are experiments showing a "behavioral sink" in mice when given everything needed but space. And who knows, humans could even be of interest as a "model organism" for scientifically inclined alien species...
> But while such a civilization would be energy rich, wouldn't planets in the habitable zone still be scarce?
Probably not. There's around a billion stars in the Milky Way galaxy alone, and even more in nearby Andromeda. If some civilization has the technology to travel to our system (which is likely tens of light-years away if not much farther), then it'll also have the tech to go to many, many, many other systems other than ours, which also have habitable-zone planets, and are probably more conveniently-located.
The only real exception is if there's a race that's not all that advanced, and is located very, very close to us, such as in the Alpha Centauri system, 4ly away, so that we're just close enough to make travel here feasible for them, but other habitable-zone planets are significantly farther so that it makes more sense for them to attack us rather than just find someplace else.
But as we're already figuring out now, a mere 4ly is already a really, really long distance with our technology. Our longest-range probes have only gone a small fraction of that distance, and they've just about left the system. It'll be tens of thousands of years for them to go that distance at their current speed. So traveling that distance is already rather unimaginable for us without something like a generation ship or cryo-storage ("suspended animation"), and when you have that, why bother fighting a war if you can just continue on?
Finally, if you have the technology to build a generation ship that can work reliably for 10,000+ years supporting life, you probably have the technology to mine asteroids, build habitats on the Moon and Mars, build large habitats with artificial gravity (by spinning) in Lagrangian points, etc. In short, you already have the technology to make habitats perfectly suited for your species, and there's a whole solar system full of building materials at your disposal. If you have that, why would you want to travel such a long distance just so you can steal a planet from some other race, when it's very unlikely that planet will even be suitable for your biology without significant terraforming?
In a nutshell, the problem with this kind of thinking, and a lot of sci-fi in general, is that it assumes that interstellar space travel is much cheaper and easier than artificial habitat construction, when in fact the reverse is true. This is not to say that artificial habitat construction is that easy either; we still haven't perfected that for really long-term applications. But interstellar travel is really, really hard.
Now, of course, it is possible that we've completely overlooked some fundamental physics and it's actually not that hard to travel light-years very quickly; this would change the equation entirely. There's a Neal Stephenson short story about this, where some warlike and somewhat primitive aliens attack Earth, and are easily defeated by our far-superior weaponry (they basically had 19th-century cannon technology). So the humans get their technology and figure out that faster-than-light travel is actually really easy, we had just overlooked something simple all this time; at the end, the aliens are crying about what they've done, because then the humans set out to become galactic conquerors.
> There's a Neal Stephenson short story about this, where some warlike and somewhat primitive aliens attack Earth, and are easily defeated by our far-superior weaponry...
Is that maybe The Road Not Taken by Harry Turtledove?
Scarcity might go away, but religion might not. Imagine a fanatically religious and advanced civilization. Their book tells them to eradicate all non believers from the universe.
You might enjoy reading John C. Wright's "Count to a Trillion" series, which does some thinking about how starfaring alien races, governed by game theory, might actually operate.
I don't think there's ever going to be a point when a race has "enough" and doesn't want to explore or build any more. Our ambition should grow with our capabilities. Once you can control a star, why not work on a galaxy?
The big reason is that you'd need a brand new physics to project power over interstellar distances.
Every outpost of the empire will essentially have unlimited manufacturing capability and it will take decades to project force, decades the outpost can spend making sure the amount of matter they have devoted to war exceeds the tiny amount of war matter the central empire threw out into space.
The series of novels specifically deals with time frames much longer than "decades". The first book spans a few centuries, the second and third span millenia, the fourth spans tens of millennia, and the fifth and sixth (not out yet) are supposed to reach much farther.
The big idea of the book is that Einstein isn't wrong about C being the speed limit. Therefore, to be a starfaring race requires the ability to make commitments and hold to them over extremely long timespans. The connection to game theory is that, as in the Prisoner's Dilemma, the only way you can really make predictably right decisions in cooperation with other entities is if your decision-making formulas are spelled out mathematically in advance; so all can predict how you will act. The first book begins with mankind discovering the galaxy's "rules" on a kind of signpost at a nearby star.
My point is that the very concept of an interstellar resource war, and thus the concept of interstellar control, is incoherent given our present physics. You can take over a system that isn't technologically enabled, but that's it, the resources available to a technologically enabled system are greater than the resources that can be sent into the system.
I'm not sure that's really true. What would it take to wipe out all the denizens of a star system? Maybe a few million atomic bombs? Certainly less than the mass of a small moon. And if that then gave you control of a whole star system's worth of matter and energy, it should be more than enough to fuel the conquest of the next star, and so on.
So it's certainly feasible for an advanced race to build a star empire; the question is why they'd want to do it. If we're talking about humans you might say ambition or imagination. If Vulcans, maybe they'd think it logical to pre-emptively become stronger than any potential aggressors.
That would work against a system incapable of similar production, but given roughly equal capacity, the target system could devote a small planets worth of material to defensive missiles.
You could slam a bunch of mass into a system at extreme speeds, but then they just have to hop into life boats until the storm ends (if they have the capacity to ponder traveling the stars, they have the capacity to spend a decade on a space station).
That's a "current thinking" issue. Prior to industrialization, humanity (statistically per capita) didn't care about preservation. In search or resources you get marginalized conservation thinking. Never-ever is a fantasy, because over a long enough period of time every priority can and will change.
Lets say they will. How is conquering a far off enemy worth it economically? It would be easier from a resource, political, technical, and moral perspective to build out large solar arrays or build more nuclear plants (or more fantastically, build out a Dyson sphere) than a space war. We're not post-scarcity, nor even close to it, but we certainly have better options than mindless destruction for energy. Now imagine us 5,000 or 10,000 or 100,000 years from now. Why would we fly to some far off planet to murder everyone for their resources? The universe is teeming with energy and resources. Its simpler and more ethical to just tap local-ish uninhabited resources.
Arguably, if your species is mind-mindbogglingly stupid enough to declare war constantly and against the basic rules of game-theory then I doubt your society will survive the nuclear weapons stage anyway and won't ever be in the stars. The nice thing about the Drake equation is that it suggests that Klingon-esque societies don't make it to the space-faring stage, which is nice.
We can't predict motivations of other forms of life, can we? They are completely different (in theory). They even can build a trap to make evevryone who will get there happy. Or to hear their story. I dont know.
I don't think we currently have a very good idea of how much of what we're like is due to universal properties, and how much is path dependent and wouldn't show up in a completely independently evolved ecosystem.
Greed and selfishness seem to come from evolution in a very robust way. Every time it fails to come a little bit, there's a huge change in some ecosystem or all of them.
But then, maybe a species able to colonize a galaxy can only appear as consequence of those rare exceptions. We, as a not completely selfish species are evidence for that.
These two books were hands-down the best thing I have ever read in my life. Be careful though - it takes a while to get going, but halfway into the first book the universe is fully established and the thing really takes off.
Also, be extra careful as the first book ends in a cliffhanger (literally), so be prepared to read the two huge books in one go (not that you'd be able to stop anyways)
Good timing because I just started this last week after finishing Vinge's "Zones of Thought" series. I guess I'm on something of a space opera kick lately.
In that case, let me recommend the Vorkosigan saga, if you haven't read it yet. One of the best book series I've ever read, definitely the best among space opera.
Are the sequels/prequels worth reading? I read the first one last year and enjoyed it, but the follow up reviews made it seem like the others novels might spoil it.
If I was building a Dyson sphere I would launch multiple modular solar panels into orbit around the star. This is the cheapest scalable way to do it while I collect resources and send more as my energy needs increase.
The problem then is getting that energy out. I'd use lasers from my panels to my planet. That means my solar panel collective in orbit around the star will have to always point to my planet for maximum efficiency so I don't have useless panels since there's no way i'm building a battery at star energy scale on each panel.
The dimming you see would then be based on the orbit time of my planet around the star, since the panel half halo will always be pointing at my planet. Essentially geostationary around the star.
We'd see bits of time where the dwarf was in front of the twin and burning much much brighter, the accretion disk on the dwarf would be larger than the dwarf and giving off high energy photons as it consumes the incoming matter. We haven't seen any spikes in the light level, only dips. It's possible it's behind the other star still but I don't think we've seen anything else to indicate that.
your planet (and most of the solar system) has been dismantled to build the Dyson sphere, the system is now ruled by DAO-like AI agents running on computronium. You upload yourself and a few other survivors on a small can-sized spaceship and flee the system in search of a new home.
Why would light be reflected? The point is to convert it to energy as efficiently as possible. If they can do that with 99% efficiency, there's not much left to reflect.
But by the time you're building a Dyson Sphere, the vast majority of the people are probably already living in space habitats. There's not much use for stellar-scale energy if everybody still fits on a single planet.
My wager: It's a fleet of mega-spaceships passing across the star, probably much closer to us than to the remote star. Hence irregular dimming that doesn't seem to repeat predictably.
Keeping in mind that the star is 1480 light-years avay, the fleet passed across the star about thousand years ago. Or they're still flying toward us...
It's 93 million miles to the Sun and 1/4 million miles to the Moon. "A few million miles away" places it very close by.
Even a few billion miles is still inside the solar system. Pluto is about 4 billion miles away.
It's difficult for something to stay between the Earth and a star and be nearby. The Earth moves around the Sun - this provides a baseline to measure stellar parallax, https://en.wikipedia.org/wiki/Stellar_parallax - and anything close to the Sun is also affected by it gravity. That "close" includes regions well beyond Pluto.
"Occultations" are when one object blocks another. For example, detailed observations of when Pluto went by a star gave us clues that Pluto has a very thin atmosphere. Asteroids also cause occultations, see https://en.wikipedia.org/wiki/Occultation#Occultations_by_as... . They can be used to figure out the size of an object. That page shows an depiction of a occultation by Makemake, which is 50 AU out (further out than Pluto). Its shadow is on the Earth for only a few minutes, and it's over 1400km across.
Measuring absolute brightness is hard. It would be good to compare the measurement error is in brightness of a reference star of about the same magnitude and distance(and even perhaps a known variable star) to the observed changes in this star.
In the lab under ideal conditions with ideal light sources, it's pretty common for there to be >2.5% error in these types of measurements. For those used to dB unit, this is a ~0.1dB change. In optics, it's very easy to introduce error at this level.
This was in fact the original concept as envisioned by Dyson. He pointed out that a solid sphere would be mechanically impossible but the logical way to build such a structure would involve a "swarm of objects".
(I still think that Dyson spheres are an idiotic thing to build. If you're worried about getting energy for your civilization, and you can do stellar-scale engineering, there are better things to do with a star's mass than let it waste its fuel in a big, uncontrolled trash fire, collecting it with solar cells or whatever).
Not really; the energy density in the core of our sun is about 100 watts / cubic meter. (Energy density is a LOT higher in more spectacular events, like supernova and the first few milliseconds of a hydrogen bomb's fun-time).
Smaller stars burn fuel more efficiently. Our sun is good for about 4-6 billion years; a much smaller star will last several trillion years.
My issue with the whole "alien civilization" idea is that we are seeing what happened around that star some 1,400 years ago, which means if they were building a Dyson sphere that long ago, it's unimaginable what tech they have today. I have a hard time accepting that an intelligent species could be that far ahead of us technology wise, but I could be wrong!
The universe is billions of years old. There's no reason to think that our arrival (as an intelligent species) is uniquely tied to this particular time period.
1,400 years is really small compared to the history of life on Earth. It doesn’t seem all that unlikely that other planets might have had millions of years of head start.
If they were building a Dyson sphere today, it would still be unimaginable. A construct of such complexity and magnitude, that we have almost have trouble _thinking_ about it.
I have a hard time thinking that any intelligent life we were to encounter would be on "our scale", in either direction. They would likely be vastly superior or vastly inferior. Think "they are ants, we are human" or worse "we are ants, they are human".
Why do you have a hard time with that? Are we some sort of special snowflake? Was life formed all at the same time everywhere? For all we know alien civilisations have been around for a billion years already.
My wager: The star is being eaten by a cosmic horror called Hellstar and it will be soon coming our way. Now excuse me while I take off my Junji Ito hat.
Or a space goat. My money is equally split between a Dyson sphere that is tearing itself apart (because: low bidder on the project, some things just never change) or a gigantic space goat that is eating the star.
In this series he details several hypotheses and ranks them.