There is also Topopolis, or cosmic spaghetti. Essentially a chain of O’Neal colonies. It can be built up, bit by bit.
While this only covers some aspects above, remember the coriolis effect.
A 2001 style spacecraft is too small, and a human being would become nauseous and the jogging scene would have been impossible.
In-fact it would probably require extreme selection processes or disabling of the inner ear structures to even stand up in that size of an artificial gravity solution.
More wasteful than building a giant megastructure?
I suppose what I’m getting at why do you need a single structure that could hold thousands of conventional terrestrial civilizations? If you don’t have a population that large, then you have a lot of empty wasted space and would be better off with more, but smaller habitats (mere Earth-ish sized).
I just use escape velocity as a benchmark to give a sense of scale. It’s ridiculously fast for any sort of train or terrestrial aircraft.
That’s a bit dubious, as they are made of fictional materials. Plus many of them depend on the star they orbit for energy, so they have the same problems Earth will have in a few billion years.
Much more in terms of colonization. As another poster mentioned up thread, there is a lot of material under our feet that is totally useless and/or inaccessible. There is iron, for instance, to build a billion civilizations on par with what we have currently, but it’s in the core and we can’t get at it. Same goes for pretty much everything else.
The trick to building megastructures is being able to access space and get out of our gravity well in an economic fashion (well, that and surviving in space). Assuming you can do that you have access to the materials to build habitat for all of humanity many times over just from the primary asteroid belts alone. Once you get to the destroy Mercury for materials stage you could have a civilization that makes most science fiction renditions look anemic wrt the populations you could support. And you’d be close if not beyond having to worry about a single large disaster taking out your species or setting you back to the dark ages…you might even be (relatively) immortal as a species at that point, since by then you could be from close in orbits all the way to beyond the Oort cloud, and if you can be bothered as a species into other, near star systems.
Well, that was with magic alien tech and, most importantly, with magic super strong and really unrealistic materials (since I assume you are talking about Ringworld). I guess the point of all of this is we could have such a large population without alien magic materials if we didn’t need to build one ridiculous structure and could settle for many, and it would be there for us to expand into. It’s why we wouldn’t build one large mega-megastructure, but a bunch of them. So, if we had a design for a structure that could support, say, a million people, as we needed more we’d have more. If we didn’t need them because we didn’t expand to be a species of hundreds of billions then we might make them for other reasons…such as wildlife preserves, say…or preserves for extinct species we can science magic back to life.
I linked to Issac’s channel, watch some of the videos. None of the stuff he is talking about is beyond or outside of science or physics. It might not be practical or do-able, but it’s all possible.
Also, wrt the Earth and a few billion years, if you get to the level where you can be a K2 civilization it won’t be an issue. We could move the Earth, or we could alter the sun (lift materials off of the sun both for use and to alter the red giant phase…maybe make it a red dwarf that would burn for trillions of years instead of billions) or use the technology of these megastructures to just move the population outward to the Kuiper Belt or Oort Cloud. The possibilities are endless IF you have this sort of technology and the will to use it as a species. Humanity could potentially live until either the big rip/big crunch period or until the last of the blackholes in our cluster finally evaporates away in a few hundred trillion years, give or take.
I think this was the episode Wesley Clark was referring to on IA’s channel. It’s called Civilizations at the End of Time: Iron Stars. I wouldn’t recommend this episode as the first one to check out on the channel, however, as it builds on earlier ones. If you are interested, OP, I linked earlier in the thread to his series on megastructures which, again, will answer a lot of the questions you are asking. It is, IMHO, a very interesting channel and series and worth the time spent.
Well here’s the deal.
Even if we got 5,000 to 50,000 years into the future, had spread colonies around the solar system and still hadn’t figured out how to do FTL, we should still spread across the stars. Not with million year colony ships, but by sending out waves of generation ships to greet passing stars.
If you look at this chart, there’s some relatively high speed stars that will pass by in the future. Barnard’s Star will reach it’s closest approach in just over 10,000 years, then go speeding away. Ross 248 will approach even closer in 38-40,000 years before passing us by. Gliese 445 another 10,000 years after that.
Longer term, Gliese 710, now @ 69 light years away, may pass within one light year of the sun about 1.4 million years from now.
Hitch a ride, head out into the galaxy using them as carriers.
Here’s the thing. If you have a spaceship that can take a colony of humans on a sublight journey to another solar system, you don’t need the other solar system. The colonists can just live on their spaceship forever. If they can’t live on their spaceship forever, then they don’t have the technology to survive that sublight trip to another solar system.
Eh, there’s a lot of assumptions with that conclusion. You can estimate the resources for a 2,000 year journey, you can’t provide it with unlimited resources and the ability to keep dodging hazards forever. There would be zero reasons to seal people in a limited bubble, launch them out into endless space and say “Good Luck!”. There would, however, be reasons to send them out to nearby passing stars.
I’d say that a bit differently. If you can get a colony to another star system you don’t ‘need’ to go because all the resources even the largest civilization would ‘need’ is already at your disposal. Since it doesn’t take forever to get to another star system you don’t HAVE to have a colony ship that can last that long…only one that can last and support your colonists for a century or so (and that’s not all travel time, I’m factoring in time to spin up the colony).
It’s one of the things that a lot of science fiction, especially in movies gets wrong IMHO. Especially the dystopian ones where you have a civilization that spans the galaxy or even multiple star systems…or even ones that span this one-star system. Once you can do that you aren’t going to have a few rich people and billions of poor ones because the resources available to such a civilization are literally impossible to conceive for most people.
But what is the difference if the iron is trapped in the Earth’s core or being used as the floor of a giant space habitat? In both cases, it’s really only being used to “walk on”.
Still need technology for moving millions of tons of material through space.
I don’t know. A structure that could support a million people in space would need to be as large as Manhattan. Many times larger if you want to make it self-sustaining with crops and livestock. And even then, that’s barely a fraction of the Earth’s population of billions.
And good luck building the most complicated machine ever built so that it can function in the most hostile environment longer than we’ve had industrial machinery.
Given another couple of thousands of years and conquering the solar system in the mean time, I’m not going to preemptively call those future humans too stupid to figure this out.
I don’t know…maybe 20 orders of magnitude difference? 
The real issue though is that it would be easier to create megastructures in space than terraforming an entire planet to suit our needs.
Certainly, but we are pretty good at moving a lot of stuff around to suit our needs. As humans, it’s kind of our thing. The materials are all up there, we would just have to learn how to exploit it and move it around to suit our needs. But a K1 civilization could do it wrt building large-scale megastructures in space. You asked what problems your list solves and that would be one of them. Another that sort of goes hand in hand is to move a large population of humans and other species off this planet so we don’t have a point source failure, so to speak. Another would be that there are just vast sources of material up there, material that we could use to continue to expand our civilization.
And if you made a million of them? Or a billion? It’s not like space (meaning the room) in the solar system is running out or anything, nor would materials be a real issue as the mass is all out there for the taking…if you have the technology and drive to do it. We don’t right now, but that’s not what you were asking, you were asking a question about what problems they ‘solve’, which assumes we do have the technology. And we probably will sometime in the future…100 years? 1000? I’d guess somewhere between those two. There are also megastructures we could do right here on Earth, such as that archology videoI linked to earlier.
I guess what you need to decide is if you want to continue to talk about what problem these things solve or whether they can be built at all, as that seems to be where you are going with this post.
Did you listen to any of the videos I linked too? Just curious.
Generally, megastructues are neat things that no one would have an actual reason to build and that require magic to make work in the first place. The original Dyson Sphere concept wasn’t a giant earth-orbit-sized shell around a star, it was a collection of lots of smaller habitats and solar energy collectors that together surrounded the star. That’s something that can be put together piecemeal over millennia, and that doesn’t require any magic to work. The solid Dyson Shell concept, on the other hand, requires magical materials and probably some kind of magical gravity, and would have to be planned and built as one big project. “Build space habitats, then more later, eventually have as many as you can possibly support” is reasonable , “build a huge structure using magic and finish it before any people can move in” doesn’t seem very likely.
There is a lot of weirdly awful thinking about generation ships. Why would you seal people in a limited bubble instead of making the ship capable of sending out smaller craft, when you’d need that for colonization anyway? Why would the ship need to be provided with unlimited resources when it can gather resources as it goes? Why would you prevent the people living on the ship from maintaining and upgrading it, or from building additional ships over time? Why is it any worse for a ship to ‘dodge hazards forever’ than for a colony to do so?
IMO if you have the tech to build generation ships that aren’t a complete ‘hail mary’, you’ve got the tech to build mobile space habitats that serve as indefinite living space and don’t need to colonize a particular area. While the idea of a generation ship is that it takes colonists to a planet to colonize, I don’t see why the inhabitants of the ship would want to land down on a planet instead of expanding the ‘land’ that they and their grandparents grew up in - especially if, as seems to be the case, planets earth-like enough that a human can walk around without life support equipment are vanishingly rare.
What resources are you expecting to find in interstellar space?
One challenge no one has mentioned regarding the generation-ship’s 2000 year journey is the sociological aspects. 2000 years is a long-ass time. If science fiction has taught me anything it’s that in a couple dozen generations cooped up on board this ship, people will likely have forgotten about their mission or purpose as anything other than folk tales and legends. Depending on the size and nature of the ship, they might not even realize they are on a spacecraft. And that’s best case. Worst case, their society might collapse into primitive tribalism or some of them evolve/devolve into some sort of cybernetic mutant cannibals.
I suppose both. To address the “problems” they solve, my engineer’s mind also must consider the problems they create. Or at the very least, the technical challenges that must be overcome and whether those efforts would be better spent solving those problems in other ways.
I also suppose one of the issues is trying to imagine these objects in the context of our current civilization. I would imagine it would be like ancient Roman’s trying to ponder what an advanced civilization would need of roads that can accommodate thousands of “wagons” that weigh up to 40 tons travelling 80 mph. It doesn’t make sense in the context of our current levels of technology.
But if you look at a fictional star-faring civilization where interplanetary travel is as routine as terrestrial sea or commercial air travel it makes more sense. Like I can imagine a developer on an “ecumenopolis” like Coruscant in Star Wars or Trantor in the Asimov books seeing a market for turning a nearby uninhabited planet into an inside-out orange to create a gigantic “suburb” so a trillion people don’t need to live like 21st century Earth New Yorkers.
Not yet, but I intend to.
There are rogue planets, asteroids, and comets, and some scientists estimate that there are as many as 100,000 rogue planets for every star in the galaxy. But why are you expecting the craft to go into interstellar space and never go near a star? It’s perfectly reasonable for the craft to swing by a star, then keep going, instead of settling down to make anything that would reasonably be called a colony. In fact, if your motive for space exploration is to spread out humanity to protect against any possible disaster then craft that keep moving is actually better at the job than craft that go to a star, then stop forever.
Because of the massive amount of fuel and reaction mass it would take to slow down enough to collect anything, then accelerate back up to interstellar speeds?
Right. You may ‘encounter’ such things, but if you’re traveling at, say, one light year per 1,000 years, you’re traveling at 1.1 million kilometers per hour. You’re not slowing down to look at something, you’re not sending out ships that will have to slow down from that speed and then speed up to significantly faster speeds to catch back up to you, then slow down again to rendezvous. For all practical purposes, if you send out something to investigate a rogue planet, you’ve abandoned them forever.
And if we’re talking meeting those stars passing within 4 light years, sorry, you’re NOT passing by any other stars along the way.
Well, you probably wouldn’t send a colony ship on an uninterrupted 2000 year journey, though…and you wouldn’t need to. Your best bet would be simply to send it to whatever is the nearest star that has material around it. Using technology just extrapolated from what we know today you could probably get a starship up to 10% of the speed of light, say…so, our nearest start would be, what? 100 years away, give or take? Even if you couldn’t figure out how to put the crew in hibernation sleep or whatever you could basically take a fairly small crew and a lot of frozen embryos. Arrive at your destination and start building the same kinds of habitats we would already have here, the megastructures you were asking about in your OP. Starship hangs out in the system for a few hundred years building up the system while the ship is refitted and a new crew grows up and prepares for the next hop, leaving a viable and growing colony system behind and moving on.
If we get magic sci-fi tech down the road like suspended animation or FTL or even fusion power alone it makes this even easier and more do-able. The real question is what you asked earlier…once you can do megastructures in your solar system, why would you leave? I think the answer is because we are human and some of us would just like to see what’s in the next system with our own eyes…and the one after that…and the one after that. It wouldn’t be a matter of resources, it would just be adventure and discovery at that point.
It’s not do-able today, but that doesn’t mean it’s not do-able. There are, of course, limits…like the Ringworld book examples, which WOULD require unknown and as far as we can tell today impossible materials with ridiculous strength to weight ratios. But the other things in your OP are do-able as long as you keep it in the parameters of the real. They would be hard to do, especially initially, and there will be failures and tons to learn, but you could do it. Often, we actually have the technology today to do some of it, we simply don’t want to spend the resources or the cost to benefit isn’t there.
Heck, even a 200 years ago if you talked to an engineer then and told him about the skyscrapers of today they would say ‘well, maybe you COULD do that, but it would cost the world and we’d need breakthroughs in material science. Plus, why would you want to??’.
If you do I’d appreciate your thoughts. 