The timing of winter and summer compared to what? It’s not like, without Venus, some years it’d be 3.15e7 seconds between vernal equinoces, and other years it’d be 3.17e7 seconds.
You are ignoring the impact of orbital resonance of the inner planets.
These are well known, as even discussed in exoplanet contexts.
Why do you assume that removing a resonant partner will not cause changes in our orbit, which will impact the seasons?
While imperfect some models even put the earth within 500 miles of Mars at one point if Venus just disappeared.
Or are you claiming that it is not a high risk to potentially significantly alter the orbit of the Earth around the sun?
Assuming we have enough magic to create a solid sphere with 1 AU radius out of material that would allow rotation to produce 1g (and all the other magic to keep it stable), wouldn’t everything need to be at the equator of the sphere relative to its spin? I’d guess the farther one moved away from this so-called equator would result in not only reduced simulated gravity, but also a force vector towards the equator. Does that sound correct?
And if you could make it to the “pole” of the sphere, wouldn’t you float off and be pulled towards and eventually into the sun? This assumes you don’t first impact another part of the sphere, which given its rotation speed might be somewhat messy.
Come to think of it, any atmosphere against the inside surface of the sphere would collect at the equator. Assuming you have enough air to produce 1 atmosphere there wouldn’t it quickly thin out as you moved north or south, thus making a sphere useless compared to a Ringworld-type construction for habitation? I presume that’s the intent of a Dyson sphere though, and the rest of the real estate away from the equator is for energy collection.
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Naw, we have enough material to do it (there are various different designs). Ring world certainly we have enough material.
Here are some videos from a guy describing the concept: Megastructures 1.1: Dyson Spheres - YouTube
It also begs the question of what a technologically advanced civilization would do with a macrostructure like a Dyson sphere or swarm. The essential concept is either that it allows the maximal collection of energy, or alternatively provides a massive amount of habitable and arable space for a future civilization with a population of hundreds of billions or trillions of people, but neither justification is obligatory for an advanced civilization, particularly given how wasteful a large population of individuals is with very few contributing anything whatsoever to the advancement of knowledge. There are almost certainly better ways of using energy flows than simply collecting the radiant energy from the sun by building a colossal collection system and likely better sources of energy than that of a star which can be variable and will decrease over time. The concepts of stellar and cosmic macrostructures are likely to be as quaint and unnecessary to a future technological civilization as pneumatically powered ‘difference engines’ are as compared to digital electronic computers today.
Stranger
Actually, if you bothered watching the videos he DOESN’T assume ‘technmagic materials’, but that’s neither here nor there. I know you have a disdain for the videos already. The question in the OP is simply is there enough material to make a Dyson sphere. Simple question, simple answer, if we assume you could make one (and a separate question about why you’d want too or might not want too). There is enough material in the solar system to make one. Do you agree or disagree, leaving aside your skepticism that one could or would be made at all?
Err, what I meant was a solid shell of a sphere that was hollow and the inhabitants, atmosphere, etc. were on the interior surface.
Yes, this is all true. If we assume a magic sphere that spins to provide 1 G at the equator, everything not nailed down would collect around the equator. Centrifugal gravity would get weaker and weaker as you moved towards the poles. Also as you moved towards the poles the ground would stop being perpendicular to the force of gravity, and would start slanting. By the time you got near the poles it wouldn’t be a floor anymore but a gigantic vertical wall.
Of course you’d need literal unobtainum to create a solid spinning sphere around a star since the forces tearing it apart would be greater than any material that obeys the laws of physics. This is why most fictional solid Dyson spheres with biospheres inside use antigravity to hold everything down, since that is much more plausible.
They produce food and other material goods and services, so that the snobs are free to pursue their academic interests.
Small populations produce few intellectuals. Larger populations produce more intellectuals.
Large populations also produce large numbers of people to appreciate the splendors made possible by those intellectuals.
I’m not sure where your hostility comes from but I did watch the first video in which Arthur essentially assumes that all materials from planets and other bodies can be converted into useful structural materials to make a ring or swarm of arbitrarily thin material. Setting aside the issues of constructing such a structure or system, if you just assume that you can collect all of the non-star matter in the solar system into a giant squeeze tube and somehow smoosh it out across a shell then yes, there is sufficient material. But the details of how this could actually be done, and the challenges and necessary technologies to make this actually workable underpin the question of the o.p.
I do not have the “disdain” you describe of this video series, but as I pointed out, he presents what are common science fiction concepts with some superficial detail but not much depth in analysis of how they would actually be constructed or operated; hence, citing that there is a video in which Arthur explicated about some concept is not proof that it is workable. It isn’t sufficient to say “there is X amount of material, therefore it could be formed into a uniform spherical shell of Y thickness”; to assert that it is actually viable you need to consider and address the other challenges in the construction and maintenance of such a structure, and simplyhand waving that nanobots will do it does not prove anything. It may be in the future that civilization will actually have some kind of universal atomic assembler in its bag of tricks, but from what we know right now there are an enormous number of fundamental challenges to that, so any technology predicated on this capability needs to be caveated with that assumption.
In an agrarian labor based civilization this is true; however, with existing technology we’ve already gone from substinence farming to the equivalent of a single person being able to produce enough food for thousands in the span of a couple of centuries. Given future automation technology, we can expect even higher yield and high nutrient foodstuff produced with even less human labor, and a spacefaring civilization would be incintivized to find methods of food production that do not require large swaths of open land because of the exorbitant costs associated with it. The notion of needing giant tracts of farmland used to grow conventional crops to support a burgeoning human population is like fielding modern infantry in Neopolonic volley fire formation.
Similarly, the conventional manner of producing innovation and ‘genius’ has been to more or less randomly let people breed and reap innovation from the thin upper tail of the intelligence curve, and then allowing that some of them will have access to education and encouragement to develop their intellectual capabilities. But we’re already approaching the point at which machine ‘intelligence’ is able to augment and enhance human intelligence by providing data analysis, visualization, and insights that a human brain could not produce on its own just because of the scale of the data, while genetic analysis and editing will likely permit people to select various measures of intelligence as a key facet in their children. We’ve also seen that advanced industrial nations have tended to declines in population even as they aspire in innovation. The trick isn’t simply having more people; it is having enough people with sufficient education and leisure to have the creative energy and opportunity to develop new ideas, tools, and ways of looking at the world.
There is no reason for humanity to be wedded to intelligence as randomly distributed on a normal curve; even the most conservative genomicists admit that the era in which parents will be able to select children to be of exceptional intelligence or other qualities is fast approaching, and most are very concerned about the potential misuse or unintended effects associated with it. Future human societies will almost certainly intentionally select for intelligence as the utility of human labor becomes nearly obsolete. Whether machine intelligence will ever be capable of independent creative thought (and there are good reasons to believe that it will not, or at least, not in the way that humans do), it is certainly capable of magnifying the insight and analytical capabilities of human intelligence. If James Clerk Maxwell had access to a computer and a license of Mathematica we’d probably have had special relativity and a good road toward quantum electrodynamics decades earlier instead of his laboriously making trivial hand calculations with giant
OK, so everyone in this far-future society is a supergenius. But why wouldn’t they want ten trillion supergeniuses, instead of ten billion?
Perhaps they would, but what we’ve seen of post-industrial societies today is a tendency toward underemployment, i.e. we have far more smart people than we know what to do with. And given a future of intellectual automation where virtually all straightforward tasks can be done by machine intelligence, both the real and social costs of sustaining a population in excess of that which can be usefullly employed are burdens with little benefit. We’re seeing those costs now; for someone with an advanced STEM or professional degree, they will be in their late twenties or even thirties before they actually enter the post-academic workspace, will accrue hundreds of thousands of dollars of debt (albeit due to inflated valuation), and then find themselves in competition for often scarce worthwhile jobs in their field. Automation is going to make that worse in certain fields such as law, where a lot of the work of document reviews can be highly automated, but even in sciences or engineering disciplines a lot of the basic lab and field work could potentially be automated. (Whether it should be or not is another question; critical insights often come from serendipitous discoveries stemming from failures or changes in perspective, but when you can sequence a gene in a few minutes rather than hundreds or thousands of person-hours it makes for a lot less demand for laboratory assistants.)
Perhaps some change will occur that will demand a growth of population, but I tend to think otherwise; we’ve currently vastly exceeded the natural carrying capacity of our planet largely by accident of increased agricultural yield and the time lag of the resultant impacts, but post-industrial societies in Europe, Asia, and North America are already reversing that trend with low to negative replacement birth rates, and assuming human society moves into interplanetary space, habitable volume and resources are likely to be a premium further applying limits to population growth. And this assumes we do not find some way to multiply or house intelligence in a more compact form that requires less resources and has a better thermodynamic efficiency than using water, nitrogen, carbon, and sunlight to grow plants for animals to eat. Science fiction tends to assume a far future of humanity that is essentially as we are now but with miraculous technology, but I think the innovations that will allow us to explore space or live for millennia will require fundmamental changes in physiology and likely in cognition which may make the number of ‘supergeniuses’ far less important than the ways of connecting them together and employing them in useful endeavors.
This discussion is probably too far afield from the question introduced by the o.p., and is necessarily speculative regardless of what view you take of it, so it should probably go onto its own thread rather than to continue to sidetrack this one as I’ve done here. But I do think the question of what a civilization would use a Dyson sphere or swarm for is important in addressing the architecture and thus the resources needed to realize such a system in practice.
Stranger
The main role of a Dyson Swarm is unlikely to be the provision of a home for trillions of supergeniuses, even if that is a subsidiary role; the majority of energy collected by such a swarm would power artificially intelligent processing. Since we don’t have true general artificial intelligence yet, this is certainly in the realm of science fiction. If we are worried about finding things for the supergeniuses to do, they will probably have their hands full with dealing with the artificially intelligent entities in the rest of the swarm.
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Chronos** has pointed out that light pressure from the star would act uniformly, changing the orbital characteristics of the swarm without making it impossible to maintain a stable orbit. This works better if the satellites are flat, tidally locked, and radiate waste heat uniformly from their rear-facing surfaces. If the waste heat could be directed deliberately, this could act as a station-keeping device, to counteract Poynting-Robertson drag, for example.
If the orbits are arranged in rings with a gradual progression of inclination, the result is a nice, stable torus that should be able to avoid collisions with minimal stationkeeping. My image of such a swarm can be found here
This is an animation in Celestia, by the way, made up of thousands of independently orbiting objects that never approach each other closer than tens of thousands of kilometers. To increase the amount of light that can be intercepted, more toruses (tori) could be constructed, larger or smaller, each at a different inclination.
Stranger on a Train mentions an important problem- the solar wind is not a constant, and powerful events like a Coronal Mass Ejection could cause comparatively severe disruption to a stable swarm. One idea I’ve had - (this is just about my only contribution to the Dyson Swarm concept, so it’s probably nonsense) is that these flat satellites could be warned in advance, and turn sideways to reduce their surface area with respect to the star, or maybe even open slots or blinds in their surface to let the particles through.
If the first torus, or first few tori, are constructed fom the inner planets, the collected solar energy will be sufficient to attempt the more difficult task of disassembling Jupiter and the other gas giants. This would give enough solid matter for several more tori, and also non-structural gases like hydrogen and helium that could be useful as propellant for the assembly process and station-keeping.
Eventually even this vast supply of gas will be used up - but don’t worry, there is plenty of matter left in the Sun that could be lifted out by solar-powered scoops. This scooped matter would also supply even more metallic elements, which could add to the mass of the swarm if desired.
Comets and stray asteroids and meteoroids could be targeted by beamed emissions from the satellites and turned into vapor- a peaceful use for the Nicoll-Dyson laser concept. Of course it would be more efficient to intercept them and use their mass.
A swarm of this kind would probably only intercept a tenth of the star’s luminosity, tops; note that this would still be a vast amount of energy. But if they exist, we haven’t seen them yet, so maybe advanced civilisations find something else to do.
Of course. The same is true for all science fiction - including the hardest of hard science fiction. No one can predict the future. No one knows what our engineering capabilities will be even 50 years from now, let alone in 5000 years or 5 million years. So we accept a lot of hand-waving around giant hard SF concepts like dyson spheres or generation ships, so long as they don’t cross some boundary of impossible science as we understand it today.
I enjoy Isaac Arthur’s videos, but no one should mistake them for science or practical engineering advice. Arthur is ‘world building’ the way a hard science fiction author would. His speculations remain generally in the scientifically plausible realm (except when he explicitly says it’s probably not, such as talks of FTL travel). His value is that he often goes into these things in more detail than others do, leading to some interesting speculation and interesting watching. But he’s not ‘proving’ that something is possible when he describes it - he’s just describing one possible way, maybe that something might be done in the future if we figure out how to do it. He knows enough science to not propose things that are obviously ludicrous like perpetual motion or telepathy or other woo.
I agree with this. I think the days of farming large tracts of land are going to be eventually numbered. We’re already growing synthetic meat - in the future I’m guessing that a lot of food will come from factories were nutrients plus energy go in, and finished foods come out. But we are a long, long way from that on Earth. But if we are starting from scratch in space when arable land is not available, we will have a huge incentive to improve food manufacturing without taking up space.
I totally disagree. The conventional manner of ‘producing’ innovation is to give people maximum freedom to experiment and market whatever they want, and invention is the result. Invention isn’t the result of smart people in a building - it’s an emergent property of millions of people churning ideas and refining them.
The airplane was not invented in a government think tank or in a university. It was invented by a couple of bicycle mechanics who were not obviously of higher than normal intelligence. The modern assembly line wasn’t invented by intellectuals, it was invented by an apprentice machinist who left school at age 16. The personal computer was created by two college dropouts, at a time when the intellectuals were saying that there was no demand for more than a couple of hundred computers in the world. Microsoft was started by a college dropout. Thomas Edison was an uneducated nobody. Larry Ellison, michael Dell, Paul Allen… None of these people had much formal education.
Innovation isn’t planned and directed. It emerges from the churn of actors free to follow their whims. And this should be no surprise - it’s the same pattern we seen in complex adaptive systems everywhere, and human society is certainly a complex adaptive system. Ants find food by allowing the foraging ants autonomy to forage randomly, instead of having a subspecies of smarter ants directing the rest. It can be shown that this results in pretty much an optimal search strategy when what you are searching for is an unknown unknown. And it can also be shown that in free societies, new technologies and breakthroughs tend to happen approximately as soon as they are made feasible by other enabling technologies. So much so that there are many cases of simultaneous inventions that appear very soon after they are possible. Had the Wright Brothers not existed, we would have had powered flight anyway within a couple of years, since there were competitors working on it in many countries around the world.
Agree. You need to have a large population with the freedom to follow their whims and improve their own lives, and they have to be healthy and educated enough to be able to be effective. That doesn’t necessarily mean formal education, but access to education.
As they should be. Why is it that people seem to feel that they can control their interventions in humanity, when they wouldn’t dream of, say, deciding that it would be a good thing if all the monkeys lived together without tribes, or that we should intervene and make them all smarter for their own good. It seems like when it comes to a natural ecology we are perfectly willing to admit that they are complex and that trying to shape or manage them will likely lead to disaster, yet we’re perfectly willing to do it with human society - even though our experience with doing so suggests that we’re just as likely to screw things up than make them better.
Or, the machines will have the ‘intelligence’ side locked up, and therefore we will select for creativity, or for artistic talent, or for looks, or for low-G tolerance, or… The fact is, we have no bloody idea what people in the future will do, or why. Extrapolate that to an alien civilization, and making any claims at all about what they will or won’t behave like is lunacy.
Well, except that when you get to the realm of complex systems, computing power may not help much. And it’s sure seeming to look like the non-complex stuff was actually the low hanging fruit, we are now hitting some serious limits to knowledge. Some people just haven’t realized it yet - like the people who carefully listen to the pronouncements of macroconomists whose predictions can be shown to be no better than chance because mathematical models don’t allow you to predict the future of complex adaptive systems.