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Old 11-18-2017, 12:35 PM   #11
Anaraxes
 
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Default Re: Does Interstellar Trade Make Sense For Realistic Science Fiction?

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Originally Posted by Ulzgoroth View Post
That said, at least introductory models tend to treat transportation costs as zero.
I was thinking the cost includes transportation cost.

Of course, any setting where trade is even remotely a possibility has to have pretty cheap transportation to start with. If "realistic" means "as seen from TL8 real-world science and technology", that's not going to happen at all. Too far and too much energy difference between systems.

The notion also assumes (like all the rest of economics) that there are some finite limits on production that are somewhere lower than the point you wouldn't care to consume more anyway. Post-scarcity economies need not apply. The original formulation was concerned with labor, but it could be supply of automation/replicators, or just "cost", or energy, or just raw materials (whether in-system or themselves imported at some cost). Changing the proportions of cost that come from all the input factors means you get somewhat different results for any two systems. A really transportation cost swamps the difference in the other factors. There would remain some small effect as long as system A has a different relative efficiency for producing one good over another than system B, but the benefit from trade as a proportion of the economy drops with high transportation costs.
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Old 11-18-2017, 12:47 PM   #12
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Default Re: Does Interstellar Trade Make Sense For Realistic Science Fiction?

I guess only realistic interstellar trade would be trade in information.
Some information could be nearly priceless and it's transportation by beam could be cheap enough.
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Old 11-18-2017, 01:28 PM   #13
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Default Re: Does Interstellar Trade Make Sense For Realistic Science Fiction?

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Originally Posted by Anaraxes View Post
I was thinking the cost includes transportation cost.
Doesn't work the same way. Transportation cost has an asymmetric effect - it makes your exports worth less and your imports cost more regardless of which goodsyou import or export.

The result is that with positive transportation costs, it's possible for all exchanges to be at a loss, whereas with zero transportation costs there's guaranteed to be some opportunity for comparative advantage trade unless you're effectively identical.
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The notion also assumes (like all the rest of economics) that there are some finite limits on production that are somewhere lower than the point you wouldn't care to consume more anyway. Post-scarcity economies need not apply. The original formulation was concerned with labor, but it could be supply of automation/replicators, or just "cost", or energy, or just raw materials (whether in-system or themselves imported at some cost). Changing the proportions of cost that come from all the input factors means you get somewhat different results for any two systems. A really transportation cost swamps the difference in the other factors. There would remain some small effect as long as system A has a different relative efficiency for producing one good over another than system B, but the benefit from trade as a proportion of the economy drops with high transportation costs.
I...am failing to locate a point in this?
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Old 11-18-2017, 03:34 PM   #14
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Default Re: Does Interstellar Trade Make Sense For Realistic Science Fiction?

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I...am failing to locate a point in this?
Just noting another potential limit on the applicability of the concept of comparative advantage over the range of imaginable SF settings. If production levels are fixed (relative to the speed of trade and consumption), then comparative advantage matters more. You can make that choice of "more A and less B". It's the limit on production (in the original 19th century example, labor) that creates that tradeoff. If, on the other hand, you can easily and quickly expand your productive capacity, then "more A and the same amount of B" or "more A and more B" can become attractive options as well, and the math would change.

It goes on to get even more complicated from there, of course. (For instance, having more stuff in both systems A and B is all well and good -- if there's an unlimited demand for stuff and no decline in marginal prices. Getting more from trade only matters if you want more. Real humans haven't shown any signs so far of not wanting more, but it's conceivable. Less extremely, other options like investment in capacity or R&D for efficiency become more attractive compared to just more stuff.)

At any rate, the original point was just that the intuitively obvious idea "it's cheaper for system A to make product a than it is for system B to make product a, therefore A would never import any a from B" is not actually true. Counterintuitive as it may be, it can be advantageous to import that more expensive product than it is to make it yourself, because you can focus production on even more of what you're particularly good at, giving you even more to trade and still have some left over. Mother Earth might well specialize to some degree, leaving the less-efficient colonies to fill in what's left as best they can, even though their best won't match the homeworld's best effort on that good.
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Old 11-18-2017, 05:45 PM   #15
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Default Re: Does Interstellar Trade Make Sense For Realistic Science Fiction?

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The rub is getting it to orbit in the first place, the cost of which nothing short of antigravity can fix. And reactionless thrusters help, too. Which is essentially the Traveller model. But if you want non-superscience (except for FTL), then it's hard.
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If you've got a TL10+ space elevator and don't need to cover too many AU under rockets, most of the cargo table is within the realm of possibility.
This also doesn't take into account space habitats. Earth is one of the hardest places in the solar system to take off from or land on. If you go from micro-gravity to micro-gravity things can be pretty cheap. Going from micro-gravity to a gravity well is also pretty cheap, all things considered.

There are more extreme options than space elevators. My recent favorite is the orbital ring. Its more expensive to build than a space elevator but doesn't have the throughput problems or require unknown building materials.
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Old 11-18-2017, 05:46 PM   #16
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Default Re: Does Interstellar Trade Make Sense For Realistic Science Fiction?

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Just noting another potential limit on the applicability of the concept of comparative advantage over the range of imaginable SF settings. If production levels are fixed (relative to the speed of trade and consumption), then comparative advantage matters more. You can make that choice of "more A and less B". It's the limit on production (in the original 19th century example, labor) that creates that tradeoff. If, on the other hand, you can easily and quickly expand your productive capacity, then "more A and the same amount of B" or "more A and more B" can become attractive options as well, and the math would change.
Works almost exactly the same if you're trading off what production to expand as if you're trading off present production between goods.
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It goes on to get even more complicated from there, of course. (For instance, having more stuff in both systems A and B is all well and good -- if there's an unlimited demand for stuff and no decline in marginal prices. Getting more from trade only matters if you want more. Real humans haven't shown any signs so far of not wanting more, but it's conceivable. Less extremely, other options like investment in capacity or R&D for efficiency become more attractive compared to just more stuff.)
Capital investment or R&D can be modeled as another kind of stuff that you can produce.
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At any rate, the original point was just that the intuitively obvious idea "it's cheaper for system A to make product a than it is for system B to make product a, therefore A would never import any a from B" is not actually true. Counterintuitive as it may be, it can be advantageous to import that more expensive product than it is to make it yourself, because you can focus production on even more of what you're particularly good at, giving you even more to trade and still have some left over. Mother Earth might well specialize to some degree, leaving the less-efficient colonies to fill in what's left as best they can, even though their best won't match the homeworld's best effort on that good.
That appears to be just a basic statement of comparative advantage concepts, which is rather redundant...
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Old 11-18-2017, 06:24 PM   #17
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Default Re: Does Interstellar Trade Make Sense For Realistic Science Fiction?

Yes, interstellar trade is feasible, by some definitions of interstellar trade.

Realistic Model 1: "Basically Today, but with near-C engines."

We might call this the "Type 1 civilization." So, let's postulate a society that isn't vastly technologically different from our own, except with some sort of advanced engine that could reach near C if you built a sufficiently large ship that was mostly fuel. The cost of the ship is enormous, and the fuel is probably cheap "per gallon," but you've need a lot of it.

Transportation in this model takes literally years (probably closer to the order of decades for a round trip), and investing in a trade fleet is an astronomical cost, but it should be noted that if we can travel to the stars, we can get around our own solar system pretty well, so we've got vastly more wealth than we have now, making this a touch more practical. Even so, given the costs involved, this is a once-in-a-lifetime trip. You don't have tramp freighters, you have major liners that some corporation invested in (and it would have to be a corporation; without major life extensions, you'd see a ship leave and return with cargo once every 20 years or so, so you'd see such trips maybe 3 times in your life; a corporation would have the longevity that these things sort of start to make sense).

In such a scenario, the only things worth transporting are things that are beyond valuable and things you literally can't get anywhere else. "Gold" might be a good example of the first, but realize by the time we have access to the Asteroid belt, the amount of gold we'll have will be stupid, and this holds true for almost all rare materials. Unless it turned out that some locally attainable element (say, unobtanium) was so fantastically valuable that it was worth collecting all we could find, then I think you'd be limited to things like exotic biologicals, scientific samples and people. The scale of these journeys feels less like "Trade" and more like "Expeditions."

Realistic Model 2: A Truly Advanced Civilization

Realistically, a civilization capable of interstellar travel is capable of lots of other things too. It's not unreasonable to say that they have a dyson swarm, nanofabrication and the capability to utterly dismantle heavenly objects (asteroids at least, but you could probably tear apart a planet or even engage in starlifting at this point). Call this your Type 2 civilization.

In such a case, there's no such thing as an "unattainable item." You can literally build anything provided you have the resources for it, and while mashing atoms together to create new elements is rarely practical, it might be more practical than moving those atoms across interstellar distances.

While such a civilization almost certainly has life-extension procedures that make the long journeys less of a hassle, they also have less reasons to make them. Their local star system has more than enough resources for them, and the neat things people find in other star systems, like exotic biologicals or scientific samples, might be better sent as highly detailed scans beamed via some means of interstellar communication (not cheap, but cheaper than interstellar travel). Even people might be best sent this way: send some sort of automated factory probes out to other star systems, have them set up receiving stations, and they can build robot bodies for people, and then "travelers" upload a scan of their mind, transmit it to the "colony," upload into the robot, see the sites, then upload the new memories and transmit them home, where the "traveler" can integrate them into his mind as he wishes.

Realistic Model 3: Black Hole Farmers

So there's an interesting argument. It goes something like this: the Landauer principle suggests that the colder it is, the cheaper it is to compute. It's also true that energy and matter are rapidly dissipating. Finally, it's also true that dropping matter into a black hole for a bit of energy ("Black Hole Farming) is a spectacularly cheap way to get energy. If computation (say, to emulate minds, or to do some seriously cool research) is your aim, it might make more sense for the universe to cool off before you start making all those computations, but if you're going to do that, you'll want to hoard a lot of matter around yourself. Then, once everything has cooled off, just slowly drip matter into the black hole, collect the energy that comes out, and use it to fuel your calculations/mind emulations for a ridiculously long time.

If we imagine a truly advanced civilization, they might have mastered mind emulation uploaded their entire civilization and put everyone on ice or possibly slowed their speed of thought down. The next trick would be to find a nice black hole, bring your civilization to it, and then start to collect as much matter as you can around it, carefully stored (nearby, but safe, orbits?) for when you need it.

Given that it will take, er, a really long time for the background radiation to cool to a degree that you start to see really big gains in computation costs, you've got a lot of time to start moving matter around. Given that your civilization is all uploaded, they can run at whatever speed they want, which means they can run really slow. If you run sufficiently slow, interstellar travel doesn't feel very long anymore, and even really slow versions of travel aren't so bad. You can build stellar engines (dyson spheres with a hole) to push star towards your black hole, and you can likely do this with a lot of stars.

This is sort of the opposite of your information trade, though you can do that too, sending out probes that look at stuff and beam raw data back to your core civilization, but this civilization is worried more about collecting raw material. It should be noted that this isn't really "trade" in the sense most people mean, more like "raw resource extraction," and it's very slow and not the sort of thing exciting space captains would do and involves a mind set completely alien to the modern human, but if you want to picture the economic networks of a far future civilization, they might look something like that.
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Old 11-18-2017, 06:51 PM   #18
David Johansen
 
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Default Re: Does Interstellar Trade Make Sense For Realistic Science Fiction?

I recall an article, possibly in Analog where it was postulated that the real advantage of near C space travel is compound interest. Invest, leave for two hundred years come back, profit!
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Old 11-18-2017, 07:17 PM   #19
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Default Re: Does Interstellar Trade Make Sense For Realistic Science Fiction?

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I recall an article, possibly in Analog where it was postulated that the real advantage of near C space travel is compound interest. Invest, leave for two hundred years come back, profit!
Only an advantage if you lack other means of living further into the future or relativistic travel is cheaper than your costs of living...
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Old 11-18-2017, 07:53 PM   #20
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Default Re: Does Interstellar Trade Make Sense For Realistic Science Fiction?

It depends a lot on the assumptions you do. Basically if production is trivial and transportation expensive, then no, if opposite then yes.

It should be noted that your example of a small armed and armored 94 million ship is a kind of wrong to represent bulk freight, that is a lot more expensive than a normal freighter/ton. You would go for such a ship only to ship small amounts of valuable things to dangerous places.

A basic TL 11^ bulk freighter might be: 1 million tons/sm +14
1 Stardrive Engine; 10 billion
0.5 Fusion reactor: 5 billion
1/3 control 0.6 billion
1/3 habitat 0.3 billion maybe 9750 tons cargo
1/3 Standard reactionless 0.3 billion 1/6G
17.5 cargo 875000 tons

note that a more realistic compared to current freighters would have even smaller controls and habitats, but the spaceships line does not have smaller systems...

Cost: 16.2 billion, so using the 1.5%/month from spaceships 2, gives 243 million/month or $9.16/ton/day or very close to the $10/ton/day from spaceships 2. Notice how the stardrive is the expensive component so that is the limiting factor in making it much cheaper.

At that rate great many things become affordable to ship is the transit time is short enough.
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