Seven Dyson Sphere Candidates
centauri-dreams.org
centauri-dreams.org
> Przybylski's observations indicated unusually low amounts of iron and nickel in the star's spectrum, but higher amounts of unusual elements such as strontium, holmium, niobium, scandium, yttrium, caesium, neodymium, praseodymium, thorium, ytterbium, and uranium.
While the explanation is likely some unknown natural process, salting a star with an impossible chemical composition might also be a way for a technological species to create a monument, correct? This seems like it would involve moving less mass around than a Dyson Sphere/Swarm, although it would need a constant feed, if I understand the situation correctly.
Astonishingly, there appears to be no contemporary analysis of this star.
[0] https://en.wikipedia.org/wiki/Przybylski%27s_Star
"The Star That Shouldn't Exist" - Prof. David Kipping
https://www.youtube.com/watch?v=maMDGZOD3mI
"Why is There Plutonium in This Star? Przybylski’s Star with David Kipping" - Event Horizon
I should have stated: there appear to be no contemporary observations of this star.
Also, one of the more interesting things to me is that ytterbium, for example, has a half-life which is measured in days.
Which ytterbium are you talking about? It has 7 observationally stable isotopes[1].
[0] It's actually getting a lot better, I hit brain-rock-bottom a year ago. I literally could not think at all. Damn those ticks.
I kinda want neighbourhood opossum farms, since the opossums eat those bastard ticks.
After recovery, my brother and I laughed about this once he pointed out that I do in-fact live in a village called Deer Mountain (loose translation.) Like what does one expect? They are deer ticks, after all.
Also, I love opossums! I grew up with them in The States, but we don't seem to have them here in Europe.
I live in a high tick area as well. Did you notice any symptoms before the eyesight?
I had a few bites but since the rashes went away my doc said no need for antibiotics unless rashes come back or I get flu like symptoms, etc.
Then I got joint pain, then the really weird eyesight loss, in short order.
What I would recommend is getting the antibody tests if you have any concern. I am in the EU, so that was very cheap w/o insurance. I believe in The States they recommend prophylactic Doxycycline, at any concern, instead of testing because testing $.
Prophylactic Doxycycline is a couple pills. Since I missed that, Advanced Neuro Lyme was 30 days of 2 high-dose pills a day. In the USA, they require IV antibiotics for Advanced Neuro.
This dumb crap changed my life, so again I would ask, or demand testing for ELISA. If that comes back positive, then there will be a different "Western blot" confirmation blood test. If they say no, then find a local clinic and pay for the ELISA yourself.
https://www.mountsinai.org/health-library/tests/lyme-disease...
https://www.walkinlab.com/blog/accurate-test-lyme-disease/ ($120 for the first test, if positive then $150 confirmation)
Of course that’s just as sus if not more.
Aim JWST at that thing.
Yes please! It's less than 300M light-years away! It's crazy that we haven't done this from the ground recently. One of the issues is that it's in the Southern sky.
According to Prof. David Kipping, ~"The guys who are into these weird things have somehow never heard about this star, it just got lost in the shuffle."
Also, Kipping mentioned that some of the research was Czech-based, and not in English, which may have also been a factor.
My very uneducated guess was that two planet-like objects smashed, and there is some cloud around the star which gave those weird spectrographs?
However, this makes my dumb theory sound unlikely: https://youtu.be/maMDGZOD3mI?t=435
TL:DW; Shortlived elements like Einsteinium should not be there. We really need to take a closer look.
Another guess: it got close to a neutron star merger, and was showered with high atomic number debris. Heavy elements can be produced in mergers of such stars.
However, assuming that it's not misidentification, would it be fair to say that new physics would have to be discovered to explain things like Americium and Einsteinium?
This star appears to be so exciting. Whatever the answer is, it is going to push the boundaries of knowledge.
However, while I ain't no city-slickin' Kardashev Type II orbital mechanic, all those star shades might not be in a stable orbit over hundreds of millions of years. They might require some propulsion for station keeping. That sounds hard for anyone, across those time scales, especially as the star grows.
It might be "easier" for longevity, to terraform a Mercury type planet with unnatural chemicals, then smash a large off-plane comet into it, to create a band of non-star weird chemicals which would fall into the star and should last for millions of years, giving it a one-in-a-billion spectrograph?
edit: Come to think about it a bit more, I would argue that the latter solution is entirely within our technological grasp nearly today, as a pre-Kardashev scale civilization.
Irregular but mathematically significant/recognizable.
As for the game theory - in practical scenarios you want to use conflict theory by shelling, because game theory is too simplistic.
Essentially, any alien civilization that survives in the long term is silent and hostile. But especially silent since being hostile can reveal your location.
You'd have to explain why. Logically, the first two civilizations to "team up" would easily handle any single civilization that challenges them. A civilization that happens to beat them would find among its attractive options a Nobunaga Gambit: taking on the vanquished foe's mission of unification (since it worked until it didn't - and the one time it didn't work, there was a terrifyingly good chance that it could have).
"The Dark Forest" as an idea is inextricable from its cultural origins, a China that's rather pessimistic about inter-civilizational contact because of its recent history. That it resonates amidst a zeitgeist of global instability doesn't make it universally correct. Gene Roddenberry's competing vision might seem optimistic, but it's not naive; beneath Starfleet's cheery veneer is the Neo Princess Serenitian realpolitik of, "Peace, or else."
This assumes defense is possible. Two loud cooperating civilizations don’t seem like they’d stand much of a chance against a silent, hostile civilization that quietly chucks a few rocks at both homeworlds and any interesting-looking moons, timed to arrive at roughly the same time.
I don't think saying "logically" and then an unsubstantiated claim constitutes a proof.
If two civilizations team up, whether that makes them stronger, weaker, or equally effective, is not certain IMO.
When two human companies merge, the result is often mistrust, poor communication, poor effectiveness, and sometimes ultimately failure. Sometimes the result of the merger is more effective.
A single, decisive government can run more effective than an indecisive coalition with no clear leader.
I just don't see how a definitive conclusion is possible any way. Surely it would vary case by case.
Those are all important considerations when talking about particular circumstances. Mathematically, however, 2 is greater than 1.
I say "logically" in the sense that, across a broad view of conflicts, the larger combatant usually does the most damage. The reason why is particular to each conflict (more bodies to throw, more brains devoted to tech development, more industrial output, etc.), and when it does not happen, the reason why is also similarly particular. You can also argue whether the circumstances truly yield a "win" (as in asymmetric warfare that ends with the smaller force driving out the larger one on logistical grounds, despite sustaining heavier losses). (Also note that "war" is not "business"; alliances are more important when the outcome of lost battles isn't just lost access to capital, but lost lives).
Humans become a rabbit, the malicious species a fox, the benevolent species humans.
If the rabbit is injured, making noise and hoping for humans to help is a fools errand as the fox is more likely to hear and eat the rabbit.
This is engrained in our evolution.
What value is there to get from going into interstellar war (provided such a thing is even practical).
When discussing aliens you have to consider that their reasoning, their culture, their motivations, their technology, their customs, their values are all _alien_ to us. You have to be open minded, for every excuse we can come up with for "why not" there are infinite explanations for "why so".
Yet on a cultural level, I think the "food/slaves" narratives of alien invasion are actually failing to be open-minded enough. Mechanical labor and physical nutrition are the kinds of things that our newly industrialized post-colonial societies worry about. It's not actually a particularly "alien" idea. Thinking a much more technologically advanced society would come to Earth for the same reasons comes across to me as projecting our own anxieties and sins.
People still eat https://en.wikipedia.org/wiki/Ortolan_bunting despite the illegality, low nutritional value, and the ready availability of other options.
If you are a civ who is able to do it, surely you can grow whatever food you need at home and have advanced AI/robotics that can provide labour.
That being said, Harry Turtledove wrote a great story about interstellar travel being easy and humanity somehow missing that branch of the tech tree.
Road Not Taken: https://www.eyeofmidas.com/scifi/Turtledove_RoadNotTaken.pdf
> If you are a civ who is able to do it, surely you can grow whatever food you need at home and have advanced AI/robotics that can provide labour.
If you are the first one and want to make sure to prevent all future advanced civilizations from evolving, you send out von Neumann probes. You can tell them to build relativistic kill missiles and destroy all planets. No planets = no new civs, probably.
You don't know that. Maybe our planet once had some amazing high-energy isotope/mineral that was completely mined out.
If these aliens can not only travel but do resource extraction at interstellar distances, that implies having highly advanced fusion or annihilation reactors.
Minerals are just chemical reaction products, and therefore necessarily cost negligible energy to synthesize compared to interstellar travel. It's easier to just make the minerals you need.
Isotopes are finite in number, and we already know and largely understand all the ones are likely to ever be useful. "Island of Stability" nuclei may or may not be possible beyond that, but even if they're not only possible but also useful, they will almost certainly have halflives short enough that they will also have to be synthesized rather than mined. So, there's no competing over planets either way.
At the lower end of the tech levels where you can have interstellar industry, the only "amazingly high-energy isotope/mineral" is hydrogen fusion fuel. There's nothing in the Earth's crust or core that could be useful for them, because terrestrial planets are made out of spent nuclear detritus. Though maybe they can bring a big fusion candle and just run off with Jupiter, if they forget about their own gas giants and stars.
At the higher end of the tech scale, even hydrogen stops being a resource. Matter annihilation (e.g. via microscopic black holes) means that it doesn't matter what element or chemical your fuel is made out of when you're converting it directly to energy.
I think any resource competition argument for "dark forest" exopolitics really undersells how vast space is, and how abundant resources are. A single Jupiter with basic fusion reactors could easily sustain quadrillions of humans in enormously inefficient utopian living conditions for trillions of years. [1] It's going to need to get a lot more crowded before fighting over minerals is something that any sane interstellar civilization would worry about.
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1: https://www.wolframalpha.com/input?i=%28%28jupitermass%2Fpro...
No, it doesn't. You don't know what you don't know. Aliens can have tech based on some rare isotope/mineral/whatever.
> Minerals are just chemical reaction products, and therefore necessarily cost negligible energy to synthesize compared to interstellar travel. It's easier to just make the minerals you need.
Unless these minerals require special rare isotopes or some other material we're not yet aware.
> Isotopes are finite in number, and we already know and largely understand all the ones are likely to ever be useful.
No, we do not. Google "island of stability".
> At the lower end of the tech levels where you can have interstellar industry, the only "amazingly high-energy isotope/mineral" is hydrogen fusion fuel.
That statement isn't a fact. Unless you magically synthesized all possible isotopes and materials. Which you didn't.
> There's nothing in the Earth's crust or core that could be useful for them
But maybe there was, that's the argument.
> Matter annihilation (e.g. via microscopic black holes)
Again, you're talking about known science. Not everything. You don't know what you don't know.
> A single Jupiter with basic fusion reactors could easily sustain quadrillions of humans in enormously inefficient utopian living conditions for trillions of years.
Yes, but that has nothing to do with the argument we're having. It doesn't disprove that there might have been some rare resource (or maybe it's still here, we just didn't get to it).
You can only put so much strain on a chemical bond before the electrons decide to stop sticking together anymore. You can only get as much energy out as the mass change from splitting an atom. You can only store as much energy in a heavy nucleus as was originally put into it by the supernova that created it. Anything else would violate basic laws of physics, to such a degree that everything in our universe would presumably immediately cease to exist.
> No, we do not. Google "island of stability".
I already addressed the hypothetical island of stability in the sentence immediately after the one you quoted. The term is relative. They are expected to have longer halflives than the instantly decaying superheavies like ununoctium, but even the longer predictions of their decay properties have them disappearing far too quickly to be mined as minerals.
I'll add now that there's also no reason to believe that island of stability substances, if they even exist, will have any more particularly useful or powerful properties than any other heavy metal. When was the last time you needed to use Mendelevium for something?
> Yes, but that has nothing to do with the argument we're having. It doesn't disprove that there might have been some rare resource (or maybe it's still here, we just didn't get to it).
It disproves the idea that there might be some useful resource which you would want to go conquering for. The resources available in any star system are already more than any conceivable civilization could ever use.
The other side of this is the difficulty of interstellar travel. Reaching relativistic speeds implies turning a significant fraction of your vehicle's mass into energy. With the ability to create and manipulate such power densities, you're better off just synthesizing whatever you need.
> No, it doesn't. You don't know what you don't know.
> But maybe there was, that's the argument.
> Again, you're talking about known science. Not everything. You don't know what you don't know.
If the argument for suggesting a complete break from the known laws of physics can be summarized as "You don't know what you don't know", then you may as well argue that the universe is secretly controlled by a giant space cat which will reward us with salmon if we all shine laser pointers in our retinas every third Thursday.
"Maybe there was" is not actually an argument, in the sense that there is neither anything specifically substantiating it which can be examined, nor any falsifiable conditions which may disprove it.
And then you engage in obvious logical fallacies like talking about mendelevium, as if it's exactly the same as hypothetical stable isotopes from the island of stability. You have no idea what you're talking about, you have not produced those isotopes, no human did.
And then you engaged in completely dishonest straw man with the space cat. I never claimed that there are such isotopes or other used yet unknown natural materials, I just suggested that there may have been some.
Considering how dishonest you are, I won't respond any more.
The entire point of "science" is that you can and should make reasonable predictions based on past observations. E.G. Mendelevium. Calling that a "obvious logical fallacy" is… Disturbing, frankly.
You know, I've yet to see you make a single point that's based on anything more than "Maybe", "No, it doesn't", or "How dishonest you are". Lots of rhetoric. Not much else.
It is your choice to interpret disagreement and contradictory information as "dishonest". Have fun with that.
"I never claimed… I just suggested." Ffs.
Better to strike first than gamble.
Much harder to wipe out a civilisation that's dispersed among hundreds or thousands of smaller space colonies. Especially if many of those colonies are hidden in an asteroid belt of millions of rocks.
Whatever scattered remnants that are left of humanity hanging out in the asteroid belt are going to have a hell of a time finding food to eat or oxygen to breathe.
Do you think they'll be reliant on planets for food an oxygen? That's daft — they will be growing their own food and mining their own oxygen.
Also, I doubt they will be "scattered remnants" — there's likely to eventually be a far larger population off-planet than on.
How does this play out with two apex predators...? When you travel in bear-infested woods, the common refrain is to make your presence known -- better to let the other apex predator aware of your existence so you can both give one another a wide berth. Or the Teddy Roosevelt style - walk softly, but carry a big stick.
> This is engrained in our evolution.
Literally the exact opposite?
> Recent research has also shown that the acoustic properties of human screams can be reliably detected within noisy environments, something presumably indicative of having evolved in noisy environments, such as dense forests, where there is a strong adaptive pressure to reliably signal danger (Nandwana et al., 2015).
https://www.sciencedirect.com/science/article/pii/S014976341...
> Rabbit Basic Science: The only vocal sounds that are made are a loud high-pitched scream of terror or a range of growls and hums that denote pleasure or defence. Apprehensive or frightened rabbits will thump the ground with their hind feet. The loud thumping sounds acts as an alarm signal to other rabbits in the vicinity.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7158370/
> Screaming among rabbits indicates alarm associated with fear, pain, and psychological distress. Your rabbit may scream because it is scared of being attacked or dying. Rabbits also scream when they’re in excruciating pain, or when they’re having a seizure. …it is a sign of extreme pain, terror, or calling out for help.
https://www.rabbitcaretips.com/why-do-rabbits-scream/
> Lima beans release volatile chemical signals that are received by nearby plants of the same species when infested with spider mites. This 'message' allows the recipients to prepare themselves by activating defense genes, making them less vulnerable to attack, and also attracting another mite species that is a predator of spider mites (indirect defence).
https://en.wikipedia.org/wiki/Alarm_signal
IMO "Dark Forest Theory"— The idea that (1) nobody would ever help anyone else and (2) nobody could ever understand anyone else because (3) we're all dumb forest animals capable of nothing higher than survival, so we may as well (a) hide and (b) kill anyone that tries to talk to us— That probably says more about the people arguing for it, or about our own providence, than it does about any probable intestellar ecology.
> Humans become a rabbit, the malicious species a fox, the benevolent species humans.
In fact, if anything, using humans as the example of a benevolent society points out the absurdity of assuming that more technologically advanced polities must necessarily be malicious.
Killers don't prosper in civilized societies. And technologically advanced societies ruled by killers don't last long.
Europeans came to Africa, India and Americas with some better tech. How benevolent were europeans?
I'm a supporter of making humans detectable in any way illegal.
Not sure what the best resource would be for an outsider to delve into this field though.
Also while I'm sure a relativistic kill vehicle could neutralize a planet, will it also get all the populated moons/orbitals in the system? What if the target species is already multi-system?
If it was intercepted someone could work backward from its trajectory and determine an origin, but the odds of noticing a cold, small, dark rock at relativistic speeds early enough to do anything about it seems slim.
You will hit some ancient rocks orbiting the star, and even if people there dont need them anymore they are bound to become curious of the origin of your missiles.
If caveman-level weaponry is sufficient to take out anyone not well on their way to becoming a Type II civilization, I’m betting on the cavemen.
To send a chunk of tungsten at a relativistic velocity would mean an effort for trillions of dollars. Don't forget that it is not enough to just get a chunk of tungsten moving, you want it to hit a moving target, and you'd better add some thrusters to it and a guidance system. Is there anyone willing to pay for that?
Any civilization will need to concentrate a lot of efforts to fire a chunk of tungsten, but why might it do it? There are better ways to utilize that effort. Maybe it is a rational thing to go aggressive nevertheless, but the benefits will be in a far future while politicians needs to justify spending now. People and societies are not rational. There is no real examples of rational agents, but people still insist on treating rational agents as something real. Theoretically speaking AGI might become a rational agent, but I doubt it from a practical standpoint: AGI will be limited by a computational power and by its abilities to gather data. So it will use heuristics, and it will be not rational. It can be closer to a platonic ideal of a rational agent then human, but even that is not free of doubt. People surpisingly well do with all their heuristics and when they appear irrational it is mostly due to inability of observers to understand the real motivation of people.
You need a much more advanced civilization to be as aggressive. A civilization that can do it by spending maybe 0.1% GDP for 10 years. At least looking at humanity, I'd say that any cost higher than that will not work definitely.
Such unprovoked and costly agression having no observable results easily could end a lot of political careers.
Theoretically speaking we can ignore all these difficulties and start with the assumption that it is possible to concentrate 100% GDP on a one task for years or even decades. Practically it is impossible.
Maybe another civilization will have another structure and will be able to concentrate efforts on a larger scale then humanity? Maybe. But could you imagine such a hypothetical civilization and estimate chances of it to get to a sufficiently advanced level? I cant neither. So while I keep in mind this theoretical dreams of rational civilization purging each other, I do not assign any credibility to them. I keep myself in an uncertain state, the best state to have an open mind, to be ready to absorb any evidence or reasoning.
If we took all the proven petroleum reserves in the world, and magically converted them into kinetic energy with 100% efficiency— With zero overhead for transportation, launch, agriculture, or obeying conservation of momentum— That still wouldn't be enough to launch even a single planet killer. At most you could crater a small country, but not kill a civilization:
https://www.wolframalpha.com/input?i=2+trillion+barrels+of+o...
So let's say you do nuclear pulse propulsion like Project Orion. You've still got Tsiolkovsky's rocket equation to deal with. Assuming a speculative fusion bomb ISP of 75,000s, you would need a rocket with… over 50 orders of magnitude more mass than the entire observable universe, in order to accelerate a single proton to 0.9c:
https://www.wolframalpha.com/input?i=e%5E%280.9c%2F%2875000s...
Light sails will be huge, obvious/visible, and slow. Beamed power will run into issues with diffraction.
In fact, reaching 0.9c while you're still in the solar system plainly implies maintaining multiple hundreds of g's of acceleration over many dozen astronomical units of distance. That doesn't seem feasible at all. It's wildly beyond not only our best existing ion drives, but probably also any remotely feasible existing concept for space propulsion.
I don’t really buy the idea though - cooperation has been the strongest strength of humanity and is one of our greatest evolutionary edges. Why wouldn’t that apply on the interstellar scale too?
Humans have not even advanced beyond attempting to dominate others of the same species.
I see some criticism of dark forest theory in here, but keeping quite and shooting first are the least risky options when the inentions or capabilities of another civilization are unknown and making assumptions about the other sides friendliness could lead to eithers extinction.
It seems like a big stretch to assume aliens are going to share ideas of liberal democracy like fairness/cooperation etc (which are fairly recent) when there are groups of humans who do not
Implied was that the actions to take if we had full info are obvious. If their capabilities are known you would not have to resort to "shoot first, ask later"...
For the sake of argument let’s say we become aware of another intelligent civilization on a rocky body orbiting Proxima Centauri. They are, virtually by definition, apex predators on their homeworld. We cannot know their intentions should they learn about us.
Meanwhile, it is trivial for us to end their civilization. If we decided to, with more or less today’s technology, we could accelerate a chunk of tungsten to comical speeds and obliterate their homeworld. It would cost a fortune and it would take awhile, but we could do it. Certainly it would be orders of magnitude easier than getting humans there, setting up any sort of interstellar trade, or working to understand each other’s language and culture. And nobody at the receiving end would be the wiser until their planet essentially ceased to exist one day.
I’m not saying we want to. But we could. And importantly, they could do the same to us.
Do we:
1. Loudly announce ourselves, gambling our entire civilization that they aren’t aggressive, paranoid, misunderstand us at some point and take grave offense, realize we have a nicer planet than they do, or find some other reason to become openly hostile.
2. Shut the fuck up and hope they don’t catch our leaked radio signature from before we knew any better.
3. Strike first, just to be safe. Better us than them.
If we think that any other civilization might decide to open door number three, the calculus tilts sharply in favor of doing it first ourselves. Or at the very least going with the second option and investing a hell of a lot of money into figuring out how to detect, intercept, and redirect relativistic kill vehicles.
It doesn’t even have to be the Centauris in this scenario who are evil or paranoid. They could be just as hopelessly naïve as us and happily engage in a mutually beneficial back-and-forth. Meanwhile the Sirians (who have been quietly observing from the sidelines) one day fire off a pair of surprise care packages to the both of us, before we can get big enough to potentially threaten them and their way of life.
So, why would we go so blindly for option 3 and risk it all by being the first ones to defect in an interstellar prisoner's dilemma? Especially if we have good reasons to suspect that they've known about us for long and have remained neutral so far. After all, Proxima Centauri is quite close, and our atmosphere gives ample signals of there being life here. And we haven't been particularly quiet either.
I haven't delved deep into this, so there might be some much more tight logic to it. But my first impression is that the dark forest hypothesis seems a bit forced; sort of constructed backwards in order to explain a cool idea (that space is full of civilizations but everyone is quiet).
For example, one of the assumptions it makes is that obliterating another space-faring civilization is easy. And, at the same time, that we (and everyone) have very little information of other civilizations. I don't see how these two assumptions can hold at the same time.
And it’s just like, that’s such a colonizer mentality, trying to game out a completely unknown society and immediately focusing on threats, technology, and destruction.
I wonder, what are they like? What could we learn from them? Why are we assuming all beings are violent like us? Does it really make sense to immediately obliterate a culture you’ve never even seen? I seriously doubt it. You could send probes, spies, and try to covertly learn about them. You could send envoys, without revealing your origin, and try to gain knowledge from first contact. You may learn there is no threat, and a great deal to be discovered.
What if they had medicine which could cure every disease? Energy generators which could save our planet? What if they were simply peaceful beings with a rich beautiful history, and no desire or capacity to harm us?
The threat/destruction paradigm feels so simplistic, impoverished, and brutal.
Of course I wonder these same things. But when the consequences of becoming known to the wrong civilization are inevitable destruction, what are your alternatives?
We very nearly killed ourselves (we still might!) with nuclear weapons because we thought the other side might shoot first. This is that taken to an even further extreme: we won’t even know if we’ve been shot at until it’s far too late to do anything about it. We likely wouldn’t ever even know who sent the damn thing in the first place.
The balance of things is that silent civilizations with caveman-level technology are more than capable of wiping out noisy and naïve technologically-advanced civilizations.
You can wonder all you like about who and what these beings are and what wonders they must know of, and absolutely none of that will matter when a tungsten rod turns the planet into a fireball because you made the mistake of sending up a signal flare without having any idea that it was safe to do so.
One in a thousand civilizations could be paranoid enough to sterilize other spacefaring civilizations and it would be reason enough to be very, very quiet.
This is the presupposition that seems entirely baseless to me. An explanation has been constructed that comes to this as the only conclusion, but the assumptions in the explanation seem themselves to come from nothing. I think this is what often called "projection". Human beings are a violent creature that destroys others, so we assume these alien creatures must be. But they are aliens. We presently know nothing about aliens. My view is that we should interrogate the assumptions that lead us to your brutal conclusion. Projection of our own fears is insufficient to make the right choice.
Another question to reflect on: Why do you not destroy every person you come in contact with? They could likely kill you if they tried. But more so than legal consequences, you simply feel no desire to do so. There are reasons for your feeling that way.
More or less today’s technology could not accelerate tungsten to speeds that would obliterate a planet.
And you say it’s trivial? Who told you this?
Just run some calculations it doesn’t make sense.
(just one example, 10,000lbs of tungsten hitting the earth at 99% of light speed would not destroy it)
——
it is trivial for us to end their civilization. If we decided to, with more or less today’s technology, we could accelerate a chunk of tungsten to comical speeds and obliterate their homeworld. It would cost a fortune and it would take awhile, but we could do it.
0.99c of blueshift coming from a specific star's direction? Weird. Shoot a couple relatively slow BBs at it, and the projectile will vaporize itself around the Kuiper Belt.
Poor guys. They've now announced to the universe that they're an aggressive threat to all life around them…
I mean, the planet would exist, but it wouldn’t exactly be capable of sustaining life any more.
And my example was only 99% light speed.
At the link below you can see simulations at 99.9% light speed. An entire Egyptian pyramid, hitting Earth at this 10x higher speed, might kill off life, but it’s still not obliterating the planet.
We are not capable of accelerating any macroscopic object to .999C. Let alone a huge piece of tungsten, which still wouldn’t be powerful enough.
The ecosphere will be fine. You'll probably vaporize a small patch of ocean, and they'll get colorful sunsets for a couple days. But that's about it.
By contrast, assuming "more or less today's technology", we're now out of petroleum reserves because we used them all in our magic instant-acceleration kinetic-energy-converter.
This includes near-term technology like fusion reactors. You could take Jupiter along for fuel but still not reaching 99% of light speed. For stationary launchers, they would be super long or require enormous amounts of energy. Giant arrays of lasers aren't "possible with current technology".
Relativistic projectiles probably requires antimatter. Which are pretty far beyond our technology. There is big question is antimatter rockets are possible, they require producing and containing a lot of antimatter. Although, it instead of accelerating super fast, it is probably easier to send the antimatter.
PBS Space Time discussed these 3 options and more recently.
We wipe out their planets, then the 99% of their civilisation that isn't living on planets wipes out our planets. Now we have two very angry civilisations (without planets) in a protracted interstellar war. Great.
Many of these arguments seem to work equally well for France nuking Britain.
How is that energy expenditure going to be not noticeable to aliens?
Under certain conditions and with certain assumptions. Under other conditions and with other assumptions, the best thing for a species to do is be altruistic.
It's an impossible composition from a nuclear physics point of view, since the star shouldn't be producing these atoms, and they can't be part of the initial makeup of the star since they're unstable elements and would long be gone by now. The most likely explanation is still that something randomly collided with the star.
If it's a monument, then it certainly is the right one to send a (very vague) message far into the future, "we were here".
> This seems like it would involve moving less mass around than a Dyson Sphere/Swarm
It's a bit weird to compare two endeavors we haven't even tried yet, but making a Dyson swarm seems vastly easier than this. To pull off the salting of a star, you'd need to constantly manufacture vast amounts of exotic radioactive materials. A Dyson swarm may be massive (although there would be very light-weight ones you could build if the only function was to be a monument), but it's "just" a lot of solid bodies orbiting a star. A star salter, on the other hand, would require way more complex engineering.
https://www.nature.com/articles/189739a0.pdf
Or perhaps
https://academic.oup.com/mnras/article/477/3/3791/4964763?lo...
Or maybe you mean
https://link.springer.com/article/10.1007/BF02702326
Ok sure but there's definitely nothing like
https://link.springer.com/article/10.1007/s11963-008-1005-7
or
https://iopscience.iop.org/article/10.1086/127965/pdf
or
https://link.springer.com/chapter/10.1007/3-540-09994-8_43
or ...
There are hundreds of contemporary analyses of that star. Just search for HD 101065 and you'll find tons and tons of them.
Given your research on these papers, do you think that this is still an object worthy of closer observation with even more modern tools?
Is there enough time in the lifetime of a star to build and use those structures?
Are there plausible social arrangements stable enough to last the duration of such a project?
Are there intelligent beings with a drive to limitlessly expand their population?
A lot of the ideas behind hypothesizing swarms of space structures, each orders of magnitude more massive than Earth, feels very 1970s population/energy-crisis inspired.
If a brown dwarf, most certainly
> Are there plausible social arrangements stable enough to last the duration of such a project?
Could just be an unterminated machine process initiated by living beings at some point
> Are there intelligent beings with a drive to limitlessly expand their population?
This one, I agree. I think once we start expending enough we'll realize there's only so much that extra matter and energy will get you and it doesn't bring you closer to "solving" the universe or escaping it and you just stop going for more.
Easily. Sci-fi has misconstrued what a Dyson Sphere is to the point where the preferred nomenclature is "Dyson Swarm". A Dyson Sphere was never a rigid shell around a star. Such a thing isn't possible with any known or theorized material. And it makes no sense even if you could.
So a Dyson Swarm around our Sun would be approximately a billion O'Neil Cylinders (orbitals 2-4 miles in diameter and 10-20 miles long). You don't have to build them all at once. Build them as you need them. The more you build the more industrial capacity you have. They can all be built independently too.
I imagine it would take less than 10 years to build one once you have the capability.
> Are there intelligent beings with a drive to limitlessly expand their population?
Population is only one concern. A more driving force may well be the desire for energy and raw materials. Raw materials, and in fact most problems, can be reduced to being an energy problem. Some things will require a truly mind-boggling amount of energy eg interstellar travel.
Our Sun won't live forever. It's estimated to go into a red giant phase in 4-5 billion years, that will end up swallowing the Earth most likely. Long before then, life won't be able to exist on Earth as the Sun's solar output is increasing by about 10% every billion years. Earth as it stands now to us as we are now will be uninhabitable in ~1.6 billion years.
So to be truly long-lived we're going to have to do something about that. There are lots of options. Those include reducing the energy that hits the Earth, moving the Earth or moving our species to a different system. The last one is particularly attractive because white or red dwarves will likely exist for trillions of years. Every one of these options requires a vast amount of energy.
> ... swarms of space structures, each orders of magnitude more massive than Earth
That's not what a Dyswon Swarm is.
Since the development of contraceptives we are now selecting hard for any and all traits associated with intentional reproduction or the desire for children.
A few thousand years of this and the only thing left will be people who really want kids, or who are prone to adopt beliefs or attitudes that lead them to want kids.
Maybe this is how you get a Dyson swarm.
I’m not even including potential AI “life” in this picture.
What happens after ten generations of selection for the ones who reproduced?
(This is also a major reason I think the current right wing fertility panic is mostly bullshit with the exception of maybe a few places with unusually low rates of reproduction.)
I've decided to not have kids until artificially sentient children are a thing - and I'm hoping to find like minded individuals. Hopefully our work will help pave the ground for artificially sentient humans, and establish hybrid families of biological and AI humans.
And my AI babies will probably have faster gestation and development times than normal human babies.
But they're still going to be my babies. l will consider them human offspring, assuming I can properly socialize and humanize them. And maybe many humans will make similar choices to have artificial children.
So the range of standard gestation and child rearing times could change a lot, perhaps over a very short period!
That said, I wanted to ask a question about your argument. OP argues that the cohort of contraceptive users will simply select itself out of existence by choosing to reproduce less. You seem to argue that this can't happen because all breeding pairs are part of the global drop in fecundity. If it was happening, the trend would be for higher fecundity, not less.
That makes a strong argument for the present. Does that dismiss their claim that the drop of fecundity will lead to a critical situation where fertility collapses, and it's up to reproductive rights deniers to save the day? The reason I want to dismiss that argument, in no unclear terms, is that I believe it may be a sort of indirect or wishful thinking eugenic argument. The moral failings of reproductive rights advocates are supposed to end up ironically being the mechanism for their own genetic culling. It sounds fishy.
It would take less than a hundred years to create the first baby from scratch without human intervention. From there, the possibilities are endless. China seems like a probable candidate that lacks human rights controls and has enough biotech to build world’s first baby factory, but even if only North Korea has the tech and political will initially, the pressure on the depopulating countries would either legalize these or at least relax immigration to the extent necessary to benefit from them.
I don't think this follows. If this general line of thought were true, there would be no gay men, few gay women, and almost no infertile people in general.
Humans have complex social behaviors and are subject to a lot of higher order group selection. There can be lots of people who don’t directly participate in reproduction who indirectly do so. Community and economy are central to what made us the top large organism on Earth. We are very complex social creatures, probably the most on this planet.
But as long as humans reproduce as they do with such high overhead, the mainstream of our population is going to be selected so that the center is aligned with that.
I don't think that's necessarily true, because of the higher order selection factors like education and income. See r/K selection theory: https://en.m.wikipedia.org/wiki/R/K_selection_theory
In humans, fast breeders may be likened to r-selectors that select for quantity of offspring. They tend to be poor and uneducated and select for quantity despite constrained resources and the developmental setbacks that will cause their offspring. So fast breeding is not necessarily an overall selection advantage.
Otoh, reproductive rights believers (which are like K-selectors) tend to have higher incomes and education levels, and select for low offspring count and high investment in individual offspring. So while they may have fewer children, they will have more resources to give to their children, and their traits may enjoy selection because of this higher fitness in the offspring.
In the end, you should expect to see an equilibrium with both fast and slow reproducers - since both are in competition, both have some weaknesses and advantages, and neither is dominant. There may be a shift happening one direction or another. But it can't be a winner take all outcome, because there are too many factors in tension.
For example, the upper class are likely to remain K-selectors, because they draw their fitness from their wealth, not their offspring count. In other words, they can afford it. That won't change without social collapse or revolution.
I said up top that I think the right wing panic over this is BS. Humans are definitely K-selected, and I am not against reproductive rights.
What I was really arguing is that reproductive rights could in fact increase intentional human fertility if there are any levers evolution can pull to do this, and that a temporary dip in fertility caused by reproductive self-control might be followed by a large increase if this occurs. It's not something I'm hoping for or not hoping for, just an observation about how systems might respond to constraints.
It's not my idea really. I'm kinda parroting something I read once about evolution:
"You don't understand evolution until you understand how contraception could cause overpopulation."
When you put a road block in the way of evolution, you don't get stopped traffic. You get monster trucks that roll over the road block, off road vehicles, airplanes, and tunnel borers. Life won't stop. Trying to stop it is one thing you can do to make the gods laugh.
Of course you can only say "might" and "maybe." These are complex systems with loads of internal feedback loops and lots of interacting selective pressures and such. You can't predict them in any definite way. Psychohistory (ala the Foundation trilogy) is fantasy.
And what the difference between the skies for 2, 8, and 64 mile wide cylinders.
I wish I knew how to create those views in some 3D editor like Blender.
Cool, but GP didn't say they were. (S)he's exploring possibilities.
It's built in centuries, a star lived for billions of years (a few live for only hundreds of millions, but that's still enough).
Your other questions assume literal aliens would behave on the exact way you expect them to. That's not a sane assumption.
Let's assume a few things. They're biological (for what passes as biology on their planet, anyway), and evolved from what were originally single-celled organisms. They didn't blink into existence as Boltzman Brains or something like that. Also, they are a group of individual beings, and it wasn't some sort of global hivemind with a singular being surrounding the entire planet like some coral or whatever.
If these assumptions are valid, then yes, they'll have a drive to limitlessly expand their population, because those species that didn't have this drive became extinct in their prehistory. They'll be puzzled by it, might go through a phase where it causes them the equivalent of shame, then they'll grow past that and not care once again. And they'll expand. Because not expanding risks extinction, just like it does with us. We either expand to multiple locations outside of our planet, or we risk extinction.
> Are there plausible social arrangements stable enough to last the duration of such a project?
Maybe not. Who cares. If in the 20th century we became aware of a human Dyson spehere half-built in our solar system, a million years old and unfinished, you think we wouldn't turn around and start finishing it? Social arrangements may be unstable and cause minor disruptions, but so too are minor disruptions unstable and humanity might return to the norm on timescales relevant to the construction of a Dyson sphere.
> Is there enough time in the lifetime of a star to build and use those structures?
This is a good question. I don't know the answer to it. We've got, what, another billion years or two in ours? If the construction only takes a couple million years, seems like it might be worth it. Though the thought of the cost overruns and so forth should make even the mightiest bureaucrat shrink in terror.
> A lot of the ideas behind hypothesizing swarms of space structures, each orders of magnitude more massive than Earth, feels very 1970s population/energy-crisis inspired.
I find this hilarious in ways that I can't put into the words to share with you just how funny it is.
Not expanding does risk extinction.
And if the Dyson sphere gets built by an aggressive singularity to the tune of Stross' Accelerando, then pretty much every human in that singularity's light cone is at serious risk. If that happens, we may have to broadcast human mind vectors out into the galaxy and hope a less awful singularity catches us and gives us a simulated home with reasonable Mind Rights.
Humans have a survival impetus to settle multiple planets and star systems. But a fast burn self improving Dyson swarm might easily create more risk than it alleviates. We might therefore choose to stick to more conservative technologies to hit the stars, even with all your assumptions in place.
Slow growth swarms might be safe if there's physical reasons that a fast burn Dyson sphere is impossible. But if we uncover the potential for fast burn, we could enter a "swarms race", warring to achieve and control the most effective and rapidly accelerating swarm. In this setup, each major political power tries to start a fast burn, because otherwise an enemy will achieve it first and wipe out your swarm. The result could be, for example, multiple runaway Dyson swarms, fighting each other without our control.
Now, saying all this, I still think it would be fun to build a self improving and self replicating swarm. I just don't know if it would be very safe, politically in the short term, and for the species in the long term.
A Dyson sphere would capture the sun's energy that leaves the sun, not just the fraction that hits earth. Using that energy on earth would release far more heat than our current activities.
Human activities that convert other energy into heat don't particularly impact this process, the amount of energy from the sun is much larger.
Thus the question still stands, what happens to heat in such thing? Does it get recycled by some unknown device? Then it is closed system, you don't need input from outside. It won't get recycled? Then such device needs to get hot from dissipating that heat.
that sounds like a made up problem. the Dyson swarm isn't to collect energy to send to the home planet. it's to collect energy. where that is used is going to be wherever it's needed. mining the asteroids, local computing (the cloud is no longer just a computer on earth, it's the cloud of the swarm elements), powering interstellar trips remotely, etc. the only thing that needs to get to earth is the imports of goods and services.
First, the Earth already receives a ton of energy from the Sun that is "wasted". We estimate that at about 10^16 Watts of power, compared to humanity's energy usage, estimated at 10^10-10^11 watts. So Earth has a ton of energy dissipiation "built in" that we're not "using".
Second, there is some inefficiency and thus heat dissipation in converting solar output into usable energy. Doing that in space means a bunch of heat dissipation happens in space rather than on your planet.
Third, it's relatively straightforwward to counter any increased heat dissipation on your planet by reducing that solar output that hits your planet. How? You build something at the EArth-Sun L1 Lagrange point. Reducing that solar output that hits the EArth by 1% would likely be unnoticeable to us but could cool the Earth significantly. Also, what do you build there? Well, lots of things. More orbitals, solar power collectors, etc.
Fourth, how do you get power down to a planet? There are several candidates. One is to beam it down. This adds a conversion cost. But here's another: you build a n orbital ring [1] 100-150km above the EArth's surface. There are a ton of reasons you'd want to do this: interplanetary travel, cheap travel to and from LEO and easier travel across the planet (ie up to the ring, down to another point on Earth on cable cars, basically). But consider this: it gives you a rigid structure to attach solar power collectors to and you can run power transmission cables down from the ring to the planet's surface.
Looks like 1% would be 13.3 watts per meter, cross section of earth yields ~5.4x10^14 watts. Assuming perfect reflective, multiplying by 2/c gives 3.6x10^6 N. So like half of the thrust of one of Saturn V’s engines? So… a lot of reaction mass, or some really powerful ion engines and a ton of power. So maybe not the most practical idea.
But there's another option: statites [1]. Statites are solar power collectors that have an incredibly thin sail to the point that they don't need to orbit the Sun at all. This means you have a bunch more options for positioning. Clearly the Earth will continue to revolve around the Sun but a sufficient swarm of statites on the EArth's orbital plane could have the same net effect as, say, driving beneath a bunch of stationary umbrellas.
Or statites can themselves do station-keeping at L1. They can angle themselves to provide momentum in a bunch of directions. Or they can orbit the L1 point similar to how JWST orbits L2. Their ability to use the solar wind for directional momentum could satisfy station keeping needs.
Besides the unstable nature of L1, my main concern was actually mitigating the light pressure of the light being blocked, in order to not be blown earthward, but I guess that’s not really considering that these things could manipulate their solar sails/shades like the statites you’re mentioning.
that kind of technology probably takes hundred of thousands of years of technological development and we have had electricity for how long?
Which is why you can't hide, anyone who aims their instruments on your system will detect the heat and see that the star is obstructed.
Pretty much. The lower the temperature of that blackbody radiator, the higher energy you can extract via temperature difference. Until you reach the background radiation of the universe, which could be considered the lowest possible temperature of a thing that still extracts energy.
> Or would any radiation that sneaks past the swarm drown out the blackbody spectrum?
If that's the case, you can improve your sphere and capture that extra energy.
The energy emitted by the sun is just several orders of magnitude beyond what you can source from a planet. It's just that huge.
Also you can use your star-sized factory to make starships with fusion reactors. Not a problem.
I mean, it looks like you want to _contain_ all the energy of a sun for the sake of containing it, not to do cool stuff with it.
1. Energy loss from neutron escape. Stars don't have this issue because they are incredibly large (so your neutron will hit something else more likely than not) and gravity;
2. Vessel destruction from lost neutrons (ie neutron embrittlement);
3. Assuming D-T fusion, you're producing helium atoms. Helium is a pesky substance. It's chemically neutral and a helium atom is (AFAIK) the smallest atom, even smaller than a hydrogen atom. That means it is hard to contain and also has a tendency to damage your container;
4. Fusion reactors are, in a way, somewhat primitive. Why? Because ultimately you generate heat and turn a turbine like we do in every coal and natural gas plant. Moving parts are bad.
5. Fuel. Depending on what fuel you need, this is somewhere between a small problem (eg protium or even deuterium) to a hassle (eg tritium) to a major problem (eg He-3).
6. Waste. This depends on fuel somewhat eg do you need to use fissile materials to create Tritium?
Much more detail [1].
We obviously don't know the economics of fusion yet because it doesn't exist, but the economics of nuclear fission are, well, terrible (in both capex and opex terms).
Once you put a solar panel in space, it produces ~7 times the power. There's no loss to cloud cover, getting covered in dust/dirt, atmosphereic loss and the day/night cycle.
For an orbital, you simply cover the exterior with solar panels and you're done for power generation. No moving parts, no catastrophic failure modes (eg meltdowns in nuclear plants), it's scalable and when panels break down you simply remove them and plug in a new one.
I expect other forms of power generation will find a niche use far from the Sun in the same way that submarines have different operating characteristics to a suburb. But I'm skeptical fusion will ever be the preferred method of power generation.
[1]: https://thebulletin.org/2017/04/fusion-reactors-not-what-the...
1. You don't have a way how to transfer power from Dyson swarm without absurdly staggering losses.
2. Dyson swarm satellite would be heated up by incoming heat from Sun on one side and heated up by whatever mean you want to transfer that energy on the other side and unable to cool itself down because it is in vacuum of space. So even that power on the paper is eye popping, actual power would be fraction of a fraction of nameplate power because then you would overheated and destroy it. And now question would be, is such constrained satellite able to make more energy than it was invested into making of this satellite?
Combine 1 and 2 together and real output from such structure would be close to zero.
Why do you need to transfer power? The point of an orbital is primarily for people to live on. A single orbital could potentially support a million or more people.
Are you referring to the issue of providing power to Earth? That's... a separate issue, with different solutions. The idea of power satellites [1] has had a lot of thought. An alternative approach is to build an orbital ring [2] and hang solar power collectors off of it. You could this power directly to the ground with transmission lines.
> Dyson swarm satellite would be heated up by incoming heat from Sun on one side
An orbital would be heated on the side facing the Sun and radiate away heat away when not facing the Sun in the exact same way that the Moon is scorching hot when facing the Sun and 200 below zero when not.
A dyson swarm is just a bunch of satellites, each harnessing energy from a the same star (what they do with that energy is up to them). 1 satellite is the singular form of satellites. No need to alert NASA, they already know :)
The good news is that it seems you might be just now learning that humans have the beginnings of a dyson swarm already in the works. What a great day for you!
With this goal post moving we can start claiming that Oort cloud is a Dyson swarm. Or are all stars in this galaxy a Dyson swarm moving around central black hole? Maybe if we will move goal posts further they will!
Also, while I assumed good faith in my above reply, you've dashed my hopes: please don't ask bad-faith questions here. This is the wrong forum for that. You've shown yourself capable of announcing that you personally disagree with something. I think politely doing that is better than asking bad faith questions, pretending to want to learn, while intending to argue with the answer.
We are not capturing 10-15% of the sun's total power output.
My guess is that if you can build Dyson spheres you can build fusion reactors.
> This far the most efficient fusion reactor humanity has available to it exists approximately 1 AU away
Efficient in terms of what? With what are you comparing it to?
If you have the time and raw resources, it was possible with 1960s technology.
[1] https://en.wikipedia.org/wiki/List_of_artificial_objects_in_... .
Unless we have some magical solution which can convert waste heat into electricity and thus making such satellite working with 100% effectivity, then such satellite needs to transmit energy with very limited power otherwise it will fry itself up.
Additionally high power laser has currently something around 80% of efficiency. So if you have 10kW of input from solar array on one side, then you are transmitting 8kW via laser and 2kW into satellite itself as a heat. And again, we are in vacuum of space, so good luck with radiating 2kW of power into vacuum.
The fact, that you can't get rid of waste heat would need whole satellite to work close to 100% effectivity, which we don't have technology today
Would millions or billions of them be better? Yes.
Your description of it as a megastructure might explain some of the confusion: it wouldn't be a structure, but rather a formation of satellites not physically connected to each other.
How do you build a swarm of satellites? Well, first you make 1 satellite, then you make another... :)
My description is Freeman Dyson's description. Naturally you are allowed to come up with ImPostingOnHN's Swarm, which includes a case of zero satellites and no effect on the star emission whatsoever.
> How do you build a swarm of satellites? Well, first you make 1 satellite, then you make another... :)
Sure and the end state of completing Dyson Swarm in Solar system is not achievable with the technology we have. Now let's move on to discuss if one man with a rifle but no vehicle constitutes a Motor Rifles brigade.
Sure, for one possible end state.
The point is that we have the technology to start, because we've already started. Thus, it is achievable given enough time and effort with our current level of technological advancement.
The part we don't know how to do yet is getting the material. Building structures that large in space, the resources for it have to come from space, we cannot lift it off Earth. So we need to figure out how to mine asteroids, and maybe also how to mine Mercury. Either one would be sufficient at the start. Neither of those are a well-understood problem, let alone solved, so that's where you should invest resources if you're a billionaire looking to start a Dyson sphere and think SpaceX is on track for launch cost reduction.
I think in terms of science and engineering difficulty, it's a pretty even race as to which is more difficult between making fusion actually produce net useful energy and being able to mine & refine materials from an asteroid + build a sustainable life support system.
The reason fusion "seems easier" is because it is economically far more achievable, and there's a lot more political will behind it so it feels more possible.
Dont know what cheap means for them, but it will never be for free because abundance happens when the supply exceeds demand and I dont see the scenario where the demand for energy is declining in a long run.
This metaphor doesn’t make sense to me.
I'm guessing it's more like making a living space in the sphere itself or somewhere nearby and using the energy there (maybe exporting some percentage to Earth).
Because if we're able to build the sphere itself, we probably would already know some way to cool it down in space so it doesn't burn itself, wasting all the money that went to its construction.
No, if we have a dyson sphere, we are everywhere playa
It's the railgun problem: railguns let you trade complicated, unstable ammunition for cheap, stable slugs of metal. But the railgun imposes so much wear on its barrel, and the barrel itself is so much more expensive than in a traditional gun, that you've obliterated your cost savings.
Likewise, it's irrelevant if fusion reactors can provide infinite energy from a single gram of hydrogen, because the reactor housing itself will be an impossibly complex machine with an extremely low lifespan from dealing with the energies involved.
Is fusion possible? Probably. Will it ever be more economical than solar panels? Nope.
https://www.reddit.com/r/askscience/comments/14dtio/contactl...
https://www.reddit.com/r/AskScienceDiscussion/comments/18i71...
https://en.m.wikipedia.org/wiki/Coilgun
It would seem that even without contact there's wear issues with both force exerted on the rails or coils from the magnetic forces and also with creating plasma as the projectile exits?
The scale.
The reason to build a Dyson Sphere (or Swarm) is that you want all (or at least a large fraction) of the energy output of a star. To "build decentralized fusion reactors" that can provide the same scale of energy is even less practical than building a shell around a star and would require far more materials! Also, fusion is really simple when the ignition energy is provided for free by the gravitational compression of something the size of a star, and not so simple when you're trying to get it started on a small scale using any other form of energy for ignition. The bottom line is we don't really know if small-scale, controlled, net-energy-positive fusion is possible at all, but if it is it has a lot of overhead costs... you then have to deal with ignition energy, containment, etc. You're trying to make a mini-star and keep it tame. The physics are not favorable to this, they are favorable to star-sized stars, where gravity and fusion energy pressure can balance each other for millions of years.
Feed most of the energy of star to lasers and end up with weapon that will melt planets across the galaxy.
Honestly, don't need to expand across the galaxy if have Dyson Sphere, which could be explanation of Fermi Paradox.
To minimize theta, we need to either increase D or decrease lamda.
Lets assume we would be able to make far infrared high power lasers, at say 10,000 nm = 1e-5 m wavelength.
Lets assume we would be able to make D, the diameter of our laser beam, similar to the diameter of a typical planet, for Earth it is ~13,000 km = 13e6 m.
Theta = 1e-5 / 3.14 / 13e6 ~= 1e-13 radians.
Sun is ~ 25,000 light years from the center of our galaxy, ~= 25e3 y 3e8 m/s 31.5e6 s/year ~= 1e20 m.
Laser beam diameter, there far away, would be: 1e-13 *1e20 = 1e7 m, similar to the diameter of Earth, not much further diverged, focused and delivering the wast amount of energy all over the planet thereby evaporating it to a gas.
Indeed, what you say about the melting far away planets is possible, in theory.
The small mindness.
It's like an 1800s dude thinking aliens would do interstellar travel by having very huge horses, oh no wait...a billion of them (but still somewhat big)
"This is what an advanced race would do...with our current understanding" is an oxymoron
Sci-fi but mostly in the ’not melting down’ part.
Lets assume energy converting photovoltaics will be made of non-crystalline materials with a high light absorption coefficient allowing solar cell thickness of ~100 nm = 100e-9 m.
Sphere surface is 4pir^2, in our case 43.14150e9^2 = 3e23 m2 * 100e-9 m = 3e16 m3 is the total volume occupied by a Dyson swarm tech.
For comparison the volume of matter that Earth contains is 1e21 m3, which is 1e21/3e16 ~= 1e5 = 100,000 times larger than what is required for a Dyson swarm.
Earth, Mars and Venus each have about 10x the iron of Mercury. The asteroid belt is inconsequential.
If you consume all the iron core planets, you have about 5 cubic centimeter of iron to play with for each square centimeter of dyson sphere area.
There's a lot of unknowns for the gas giants, particularly what % of them contains iron, but Jupiter /might/ have as much as 100x earth heavy elements (including iron), but these would be at its core, and its not totally clear how you would extract them.
I think the key question is what sort of stresses you expect the sphere to be under, and thereby what materials and tensile strengths are required. It would not surprise me if the stress is basically nil (in theory you could orbit a sphere made of iron dust?) or totally infeasible for iron.
1. It can be built incrementally. What you'd probably do is build orbitals and put them in Earth's orbit around the Sun, Then you can keep adding new orbits. Ultimately you end up with a "cloud" of orbitals that will block a star's light in the same way that water molecules in a fog block light;
2. A likely candidate for an orbital is waht's called an O'Neil Cylinder: 3-4 miles in diameter, 10-20 miles long, producing Earthlike gravity on the interior by spinning. Smaller than this and it needs to spin too fast. Larger than this and you need stronger materials to stop it ripping itself apart from centrifugal forces. Stainless steel is sufficiently strong to build an O'Neil Cylinder;
3. Solar power is the most likely source for our future energy needs. It's the only known power source that directly creates power and it does so with no moving parts and no waste produced. In space, solar is so ridiculously efficient that it's unlikely fission could ever compete economically and fusion is still a pipe dream.
4. Approximately 1 in 10^9 of the Sun's output hits the EArth. That's an awful lot of "free" energy just radiating out into space. The growth potential is huge. What do we need all that energy for? History has shown we'll find a use but here's a big one: the energy cost of interstellar travel is so mind-boggling large that we'd need something like the Sun's energy output to do it. Plus an interstellar generation ship looks an awful lot like an O'Neil Cylinder.
Anyway, the article doesn't really explain why the seaerch for infrared radiation that I could see (maybe I missed it?). It's important.
A body in space like an O'Neil Cylinder will heat up, even with converting some of that energy to electricity. The only way to cool down in space is to either expel mater, which doesn't really scale, or to radiate it away into space. The wavelength of light from a radiating body is determined entirely by the temperature of that body and for any temperature we're likely to see, that means infrared radiation.
So if you look at a star with a near total Dyson Swarm you'll see much less visible light and much more IR radiation and there's really no way to hide that. Some might say you can capture the heat an turn it into energy but you can't do that with perfect efficiency (ie thermodynamics) plus the material of the orbital will just naturally radiate anyway no matter what you do.
It's extremely conservative to say that we'll have the technology to build and deploy an O'Neil Cylinder within 1000 years. Give it 10,000 years if you really want. It makes no difference. That's still the blink of an eye in cosmic terms. And that gap between having 1 and a billion is also the blink of an eye.
And once you have what's called a K2 (Kardashev-2) civilization (being one that uses the full energy output of a star) where interstellar travel becomes possible, even practical, seeding a new Dyson Swarm around another star becomes trivial and the proces continues to the point where 100 million years from now is a completely realistic time period to have a Dyson Swarm around every star in our galaxy.
A galaxy of Dyson Swarms would be so obvious to observers even millions of light years away, even at our current level of technology. The absence of seeing such a thing contributes to the idea that spacefaring life is incredibly rare.
Well, so is building Dyson swarms and spheres. I'd bet that we will figure out fusion first.
> much more IR radiation and there's really no way to hide that.
Maybe you can create a black hole in orbit and radiate into that? I saw somewhere that it might be possible to create a black hole using less hydrogen than what is available on Earth.
Dyson Swarm doesn't require new technology. It is nothing but a collection of objects orbiting and gathering energy to power its own processes. We have satellites that orbit Earth but gather energy from the Sun.
It’s still a pipe dream though
Building a Dyson Swarm, which is really just the problem of creating one self-sustaining orbital (since after that it's just a scaling issue) is really just an engineering problem. A huge one of course but we already have teh technology to create a material as strong as stainless steel and to build solar power collectors.
Currently, the big cost is getting material into space. LEO payloads are still (AFAIK) >$1000/kg. Getting that to $100/kg or even $10/kg completely changes that equation and yes, there are viable paths to reach that (eg orbital rings).
Fusion isn't even an engineering problem yet: it's a science problem. The big problem is energy loss from neutrons (as well as those neutrons destroying your reactor). That's not a problem for stars. They have gravity and are simply so large that the vast majority of neutrons are captured and feed into the overall process.
It's not clear we'll ever reasonably solve these problems. A fusion reactor is large and expensive and has many moving parts since, ultimately, we just use heat to turn a turbine in the same way a coal or NG plant does. Plus it needs fuel. Over long timescales that's still a problem. What fuel? Helium-3 (for so-called aneutronic fusion) is a big problem to source. Deuterium is easy to get. Tritium is harder to get. Protium is obviously easy to get.
Nuclear power as it currently stands on EArth cannot compete with the cost of solar power with solar panel efficiency still going up. What happens to that when you put that solar panel in space and now it's producing ~7 times as much power since day/night and weather are no longer factors and there's no energy loss to the atmosphere?
This is why I say "if" nuclear fusion will ever be economically viable. I'm not saying it won't be but there are massive hurdles to even theoretical economic nuclear fusion.
This could also be due to the fact that the dark forest hypothesis is correct.
The short version of why this seems unlikely is that there really is no hiding a K2 civilization for many reasons. For example, access to this much energy and having a megastructure as large as the Solar System (give or take) would allow you to create incredibly high resolution telescopes (with an without interferometry).
But consider this: if you, as a spacefaring civilization, want to be left alone, the best way to do it is to make sure nobody comes into your neighbourhood. If you "hide" that may happen accidentally. Isn't it better to advertise your presence and otherwise keep people away to avoid unintentional conflict?
Certainly it’s possible an asteroid munching, cylinder ring producing large machine in space can be conceived.
Moving the material (or prefabbed rings) to the proper orbit seems like a large challenge.
IR metamaterials change this, you can alter matter at the nanoscale and completely change it’s black body .
It's unclear what exactly you mean by "too fast", but assuming you're referring to human tolerances: human tolerances from NASA + Soviet studies put unambiguous, continuous tolerance without needing medication or training or anything else at 2rpm, which equates to a diameter of 450m. That is a lot smaller than an O'Neill cylinder and a lot more feasible to build sometime soon. IMO the best option is to build a 100m diameter testbed now from Earth materials, as the successor to the ISS. Then take the lessons learned there and build a 450m diameter prototype, which we can use space materials for if space mining has developed enough. We could technically throw enough material into orbit for a 450m diameter cylinder but it would be a lot of material. Any of the larger sizes and we'd need real-deal asteroid mining to make that happen.
Basically, build a small testbed now to conduct actual experiments on human health at different gravity levels + RPMs, and also start trying to figure out asteroid mining. Build a bigger prototype habitat once we can get materials for it, either from massive launch cost reductions or asteroid mining. After that point we really do need asteroid mining.
If there were 7 of these ripe for the plucking that were actual Dyson spheres, each one would be the single greatest discovery in all of humanity. Just seems a little too easy.
Suffice to say the 7 candidates in the article do not conclusively have another explanation. Hence their status as Dyson sphere candidates.
It's not saying we don't know what causes lightning therefore it must be gods. It's saying we have expectations of what lightning looks like and this looks a lot like it.
There is a significant distinction between "we've found a Dyson sphere" and "we've found an object that has the characteristics we would expect of a Dyson sphere".
think of it this way: imagine in the future we travel to Alpha Centauri and find sentient life or even the remnants of such. That would be really bad. Why? Because if there are 2 civilizations in our galaxy, how likely is it that they're next to each other? Incredibly unlikely. It heavily implies that sentient life is much more common. Now imagine if we find a third at, say, Barnard's Star.
In Fermi Paradox terms this heavily implies that there is a Great Filter ahead of us and we're more likely doomed than not.
Finding a Dyson Swarm near us has the same negative implications (for us), especially given that the gap between a partial or full Dyson Swarm and colonizing the galaxy is relatively small (~100 million yaers) in cosmic terms so how likely is it that we find a Dyson Swarm that is a) near us and b) in that narrow window between the emergence of spacefaring life and colonizing the galaxy.
If we find abundant evidence of intelligent life, there is no fermi paradox, and thus there would be no reason to explain life's fictional rarity. The answer to "where are they?" is "right over there."
The flat planier elliptical orbits (and planetary rings) come by millions of years of settling down of the otherwise chaotic convergence of material that created their systems.
These readings that spark imaginations beyond science are yet chaotic systems (from whichever influence) that have not yet settled down (debre would be in irregular orbits.)
As sciencey as finding a wormhole off the shoulder of Europa.
I thought all of these seven are estimated to be old stars which such processes should have long ago settled down.
The real problem is that Dyson spheres are wasteful because stellar fusion is thermodynamically inefficient. If you harvest the material of the star and fuse it yourself, you can keep the lights on for trillions of years.
We discovered half the planets by doing the math to predict the orbits based on the known distribution of math in the solar system.
General Relativity was initially validated by predicting mercury's orbit accurately.
And mass as well :)
Mercury is not similar mass to the sun, so this is not the three body problem
The point is that a very small difference in starting conditions yield wildly different results.
https://www.google.com/url?sa=t&source=web&rct=j&opi=8997844...
If I understood correctly, you suggest to turn the heat from fusion into a usable form of energy. On earth we'd do that using steam turbines. Harvesting only the hydrogen from the star to bring it on a planet and fuse it in a reactor seems silly, as the hydrogen is already at sufficient temperature to fuse on its own. So we could send water and steam turbines close to the sun where the turbines charge some sort of battery? Perhaps on some super elliptic orbit, where we switch the full batteries with empty batteries at the apihelion.
Or did you have something else in mind?
In contrast, a Dyson Swarm is easier for my uneducated mind to understand.
1) Much less material required
2) Much longer star lifespan (trillions of years rather than a handful of billions)
However, what's interesting is that those spheres all seem to be around red dwarf stars, which are much more active and shorter-lived than white dwarfs. They're just not as stable.
Our nearest neighbor, Proxima Centauri, is a violently active flare star -- and it's also a red dwarf with an estimated lifespan of ~4 trillion years.
I was under the impression that red dwarfs are the longest-lived stars.
But white dwarfs -- which are technically stellar remnants -- are indefinitely stable. They just keep cooling. It's surmised that they'll still be quite a lot warmer than the universe's background temperature in 10^15 years.
This has yet to be observed, but red dwarf stars, when they reach the end of their lifespan, should contract and become white dwarfs. It's said that our sun will also eventually end up as a white dwarf.
White dwarfs are superlatively stable, long-lived, and quite hot. And there are already quite a lot of them. If you're going to build a Dyson sphere/swarm, they're a very good choice. Though red dwarfs aren't bad...
Think of a Dyson Swarm ("Sphere") as the water droplets in a fog. Collectively they absorb the light going through but the water droplets (and the orbitals) are relatively sparse. So a billion orbitals around our Sun at a distance Venus and Mars would still have a mean distance between them of over 100,000km.
So how much material do you need? One estimate I've seen for a billion such orbitals is less than 1% of the mass of Mercury. Why Mercury? Because it's metal-rich and its proximity to the Sun means energy is incredibly abundant and cheap.
That's to build billions of O'Neil Cylinders.
Even if you don't need that much living room, here's something else you can build: statites. That's a portmanteau of "static satellite". Instead of orbiting the star, they are so light that the solar wind is sufficient to counterbalance the gravity. These things would simply collect energy and/or just reduce the amount of solar energy hitting something like a planet (eg to cool the EArth).
Also, the energy requirements for wormholes are well above of what one measly star can provide, not to speak of a host of other issues.
1. Interstellar travel: people don't realize just how large the energy budgets are to get to even the nearest stars, even with pure matter-to-energy conversion. This is, of course, the theoretical upper limit of efficiency but we have nothing remotely close to it. Chemical rockets are complete nonstarter becasue of the mass of the fuel makes the entire thing nonviable, even in a theoretical sense, beyond a travel time of hundreds of thousands of years. Even then you need energy to survive so it's unclear if you have enough.
So what do you do? Well, if you can reach interstellar speeds without using fuel you've solved so many problems. How do you do that? You focus energy from the Sun onto effectively a solar sail. You still need to slow down at the other end but you get some of this for "free" with resistance from the interstellar medium.
2. Computers. Our ability to utilize extra computing power shouldn't be underestimated. One possibility is virtual worlds. One estimate I've seen is that you need about 10^15 operations/second to simulate a human brain. A Matrioshka Brain (basically a Dyson Swarm that's essentially a giant computer) gets to (IIRC) ~10^80 operations/second. AIs that are basically people could live an entire virtual existence.
3. Weapons. Basically, if you have a Dyson Swarm you could sterilize the galaxy in about 100,000 years if you wanted to with a so-called Nicoll-Dyson Beam. Or use relativistic kill missiles taht are just basically lumps of metal or rock at near light speed.
Using all of the Sun's power at brain level energy efficiency would be equivalent to 10^40 operations per second. Still a quintillion times the combined brainpower of all humans currently alive.
Building a Dyson Sphere is 100% incompatible with Sierra Club philosophy!
It is about ruthlessly destroying the natural world and replacing it with something you prefer. At maximum scale!
SETI is a valid research priority.
SETI is a valid research priority. There's plenty of less speculative signs we can look for.
We have two nice theories here. People just doing the search now.
But yes, jokes aside, hypotheses are also needed for science.
My own take is that it's not science, but engineering, in the sense that it's based on already established scientific principles. It's more like a project proposal. The unknown is not whether it's physically possible, but whether we can find a civilization that has built one.