Here I asked about interstellar trade in raw materials, possible under the right conditions if necessary but not hugely useful. One of the obvious spin-offs of this was discussion of trade in manufactured goods. Personal consumer goods are a non-starter due to transit times and the rate of cultural and technological divergence at this level.

Now I'm wondering, if we take it as a given that interplanetary vessels and the likes of O'Neil Cylinders, large-scale fully integrated systems (that require no complex material inputs after they're built) of almost any size in other words, can be shipped interstellar distances. AND. The technology around these objects is basically stagnant having peaked long ago. AND. The cost of buying, and shipping, such a system is less than that of building the industrial capacity and manufacturing it yourself, support and maintenance facilities are still needed as cost just the same but you need them if you want the artifact at all.

Is a long range purchase order effective or do you still do it yourself because the ability to do it is important enough to justify the added cost? I don't want an opinion on Buy or Build, I do want specific justifications for picking one or the other option. Also does it make any difference if a star system is buying the equipment to start manufacturing these things themselves instead of finished product?

  • $\begingroup$ What do the buyers pay with? $\endgroup$ – MichaelHouse Aug 4 '17 at 18:48
  • $\begingroup$ @Byte56 Sorry what does the medium of exchange have to do with it? It's not a barter economy if that's what you're asking. $\endgroup$ – Ash Aug 4 '17 at 18:56
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    $\begingroup$ It's important because it weighs heavily on picking one option over the other. If it's raw materials, it may not make sense given the markup required for transportation costs. If it's something equally large or valuable as a manufactured good, then I'd wonder why buyers with that kind of manufacturing available wouldn't be making their own stuff. Same goes for communication, are these orders being fulfilled, or are they just cold calling settlements for mega structures? $\endgroup$ – MichaelHouse Aug 4 '17 at 19:01
  • $\begingroup$ Hi Ash. I tried to give your question a title that better summarizes what you are asking. Feel free to either roll back or to edit further if you disagree. $\endgroup$ – a CVn Aug 4 '17 at 19:33
  • $\begingroup$ @MichaelKjörling Yeah all good happy to have help. $\endgroup$ – Ash Aug 5 '17 at 18:42

The only reason I can think of for building my own would be that I have concerns about instability in my sources.

For example, it is more expensive now to ship the manufacturing equipment and begin production of my own, but what if my source decides to increase the price? What if they come under attack and lines of communication are broken? What if they go out of business? What if they decide it is not worth the time and trouble and cut me off altogether?

On the other side, Do I even need more than my initial order? If I invest in manufacturing and technology changes will I just right back where I started again? What if I run out of nearby resources, then I have to trade for the materials as well, will it still be worth it?

These are the kind of questions that come up in any risk assessment, and some people will choose to pay more up front to reduce the risk of the situation changing to their disadvantage. Think about who is making these sorts of decisions in your universe. CEOs, Presidents, Emperors, etc. What do they think is likely to happen and do they think it is likely enough to warrant the extra expense.

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    $\begingroup$ Yay someone actually read the question. Thank you. $\endgroup$ – Ash Aug 5 '17 at 18:51

We can start with what Byte56 said.

Generally, when I think of O'Neil cylinders, I think of non-FTL travel. To make shipping them instead of living in them while traveling, you would likely need FTL travel to deliver them.

In order to pay for them, you would need either a common currency and FTL communication (travel isn't necessary) to settle up books or you would need to ship an equivalent value back to the builder.

With your slow communication (~16 years to the nearest star), a common currency would be difficult.

As for justifications, most of my justifications are along the lines of it doesn't make sense but they ave based on what exactly your FTL does:

An O'Neil cylinder is big. How does the cost of your limited FTL scale with size? If the cost goes up by the square or cube of the size, it gets expensive. However, if there is a minimum cost for activating the FTL but not much scaling once it is activated then bigger is better.

If the FTL cost is based on size instead of mass, you will have issues with all the empty volume you are sending. If the FTL activation is gate like, the cylinder is the most efficient transport method but if it is bubble like, you have to expand the bubble for the entire length of the cylinder. It may be more efficient to ship the parts or machinery than the cylinder.

Also, if the cylinder isn't meant to move much once it is in place, you have the added cost of making it sturdy enough to transport (making it better to ship the pieces).

One counter argument may be a system that does not have readily available asteroids. That system may not have the inexpensive resources available to make it cost efficient to build such a large structure. In that case, I'd probably still ship the parts unless the FTL cost is purely mass based.

On the other hand, if mass is really the only factor and gate type FTL is used, the cylinders may be built as shipping containers and get re-used as habitats.

  • $\begingroup$ O'Neil cylinders don't travel, they can't, they're symmetrical and don't have anything like a main engine. There are habitats that could be used as generation ships but I choose the O'Neil because they don't go anywhere except orbit. That's 1 year to the nearest star too. $\endgroup$ – Ash Aug 5 '17 at 18:20
  • $\begingroup$ And if FTL travel is free? Because it can be you know. $\endgroup$ – Ash Aug 5 '17 at 18:52
  • $\begingroup$ @Ash There is nothing saying that an O'Neil cylinder cannot have an engine on one end. High Frontier, by Gerard K. O'Neill (amazon.com/High-Frontier-Human-Colonies-Apogee/dp/189652267X) includes cylinders with engines. They just have to be designed to take the stresses involved. $\endgroup$ – ShadoCat Aug 7 '17 at 22:40
  • $\begingroup$ @Ash, Everything that I've seen indicates that FTL travel takes a lot of energy. Bending space is hard. Creating wormholes take a bunch of energy as well. That has to be supplied from somewhere. You might want to post a reality check on your idea for FTL. $\endgroup$ – ShadoCat Aug 7 '17 at 22:44
  • $\begingroup$ I assume then that you've never heard of, at the most basic, "zero-point energy" there are layers of technology and complexity but that's the concept; in the setting it's actually more of a problem than a solution but it's there underneath. $\endgroup$ – Ash Aug 20 '17 at 7:42

Interstellar trade means that common economic principles, like borrowing money at interest, have to the deal with relativity. You might wanna take a look at Paul Krugman's article on the subject.

  • $\begingroup$ No it doesn't Interstellar Free-market Capitalism may have to but that's not the only possible set up. I'll read Mr Krugman anyway he's likely to be interesting, as in have something useful to say. $\endgroup$ – Ash Aug 5 '17 at 18:55

basic facts

  • There is a lot of resources in a star system. Whole planets worth of mass and 100 trillion times our current energy use. While there are advantages to manufacturing at scale, you are going to be doing this anyway.
  • Interstellar transport costs a lot in matter and energy. If you want to go at a remotely reasonable speed then the energy use is on scale with nuclear energy. (eg spaceship mass in nuclear fuel)
  • Protecting yourself from high speed dust and other tasks like navigation require mass. It makes more sense to send 1 small craft than 1 large one, but 1 large is easier than many small of the same mass.
  • Cost per mass of interstellar transport > cost per mass of manufacturing almost anything, even if you have to synthesize rare elements in nuclear reactions.

The most economic way to get the resources is to pack everything you need to set up a civilization into a craft and go. This craft could be pretty vast or quite tiny depending on the tech level. You could have a city on a spaceship, with lots of factories or have a shower of invisible nanobot specks sent out in the hope 1 of them doesn't hit any dust.

  • $\begingroup$ Your cost assumptions are exactly the opposite of the stated situation. $\endgroup$ – Ash Aug 5 '17 at 18:40

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