Yet another Ship population Idea.

[infojunky]

Ok, data mining for another project I had to find the number of aircraft operations as a metric.

Consider this for the United States there are 0.04 aircraft operations per person per year.

Aircraft Operations is the number of arrivals and departures combined.

Or for a Pop4 world around one a day or so.

And this includes all traffic including Smallcraft.

Right now I am figuring the onground population of ships to be around 7 times the operations number....

 

[Krikkitone]

Is that arrivals and departures of aircraft or passengers?

Although given the nature of jump travel, a better metric might be ships/pop in ~1800 Port cities.

 

[Spinward Flow]

Or for a Pop4 world around one a day or so.

Kind of depends on what the Pop4 is there "for" (so to speak).

Has the location moved past the Boom times and is now on the downswing headed towards a Bust?
Is the location an important link along a trade route?
Is the location a target for active colonization/immigration intending to grow the population (possibly to reduce overcrowding elsewhere)?
Is the location "merely an outpost" where everyone is concentrated in the "company town" ... or do you have widely scattered homesteaders who are attempting to "settle the frontier"?
Is the atmosphere hostile (to human life and/or vehicles), forcing a consolidation of arrival/departure locations due to infrastructure needs?
Does the location have a trading code (other than Non-industrial/Low Population) which would be relevant to interstellar trade supply/demand in nearby star systems?

My point being that there are going to be a LOT of variables that you can throw into the cauldron with this one. Try not to get TOO formulaic (one answer fits all).

 

[infojunky]

Is that arrivals and departures of aircraft or passengers?

Movements... A vehicle arriving or leaving....

Ship, Smallcraft.

Although given the nature of jump travel, a better metric might be ships/pop in ~1800 Port cities.

I went with a comparable traffic model.

 

[TamsinP]

There have been a few mechanisms for this published over the years.

In one of the JTAS volumes there was an article "From Port to Jump Point" (republished in the new Mongoose JTAS volumes as "From Jump Point To Port")

The WTN/BTN system in GURPS Traveller Far Trader gives some idea from the freight and passenger volumes about how many ships you could expect.

The Importance Index in T5 (and also in MgT2e's recent World Builder's Handbook) also gives a measure of how many ships per day or week you could expect.

 

[kilemall]

I’d be careful about modeling vs story. Make this like US air flights and you can’t have pirates or other sub-100D shootouts

 

[Spinward Flow]

My preference (which I posted in another thread a while back, but am updating here) is to basically do this (as a starting point):

Population: 0-6 = 1 arrival/departure per (7-Population)² days
Population: 7-8 = (Population-5)² arrivals/departures per day
Population: 9 = (Population-5)³ arrivals/departures per day
Population: A = (Population-5)⁴ arrivals/departures per day

This would be spacecraft (J0) and starships (J1+).

 

[whartung]

It's a real trick to model, IMHO.

You can take our industrialized society, and all of the traffic that we produce for trade across the globe.

If we take this as a baseline trade volume, the question becomes how much does this change if you go interstellar.

Simply, if we go on the crass assumption that "we have this much trade volume because that's how much trade we need", that is, all markets are satisfied, if we move off world, does the net trade volume remain, just some is siphoned off to a new world, or does it expand.

Using a simple case of cars in the US. We sell XXX cars. From the US, Europe, Japan. China has not quite jumped into that market yet, but when they do, I don't see the market for cars expanding, just the corporate fight for marketshare trying to wedge another country on the pie chart.

Now, if you have a new population off world, that's a new market. But, at least at the beginning, that market came from this market. That population came from here, so that's not quite "new demand", its shifted demand. Obviously, there will be more demand for "colony supplies" but that also suggests that there will be lesser demand for something else, since the population has moved. Handwavy, the net traffic doesn't change. The boardrooms want the colony to breed like rabbits to create a lot of new demand faster than population expansion on the home world.

Let's consider two established worlds, two Earths. Apparently we have 17M containers moving through the global system, doing 200M trips per year. A container moves once a month.

So, now we have two planets, two Earths, 17M each, 200M trips each. Now its a question of how much of that traffic moves interstellar. Shifts from local markets to stellar markets.

But the VOLUME should mostly remain the same. What do you think is a good shift number? 20%? More? 40M containers moved through space each year?

Obviously the problem has a lot of potential variables to it, but at 30,000 feet (or, perhaps 100D), it should look sorta like what I'm talking here.

 

[Spinward Flow]

But the VOLUME should mostly remain the same.

Not ... necessarily. It depends on your assumptions (doesn't it always, though? ).
There is kind of the same sort of question involved with international trade economics having impacts of employment and standards of living knock on effects.

One of the comparative thought experiments (which I can't find the youtube video for which explains it) is that you can have 2 countries with identical resources (so basically the same) but with one difference. Country 1 has zero international trade, while country 2 does engage in international trade beyond their own borders. What happens?

Long story short is that Country 2 winds up with higher employment, higher living standards and greater wealth than country 1. The difference between the two countries is what economists call the Intensity of Trade ... which basically amounts to a question of how much of a national economy is dependent upon imports/exports. Country 1 with no international trade would have an Intensity of Trade of 0%.

Towards the end of the video, a rather startling statistic was revealed ... that the (real world) nation with the highest Intensity of Trade globally was actually the United Kingdom, with an Intensity of Trade above 60% (if memory serves, I think it was around 64%!). Needless to say, I saw this video a few years ago pre-BREXIT ... and anyone with two brain cells to rub together can see how well raising trade barriers against yourself in an economy with such a high Intensity of Trade is working out on the world stage.

But getting back to your point, @whartung.

The way that you have framed the question/solution is basically that of a Zero Sum Game.
Trade never increases, you simply "shift things around" and everything essentially remains in a more or less steady state.

Except that's not how things work.
You reach the Zero Sum Game condition once a market is saturated, but not before.
Until that market saturation is achieved, exponential growth is possible (see S-curve adoption rates), which for the purposes of our discussion here can result in some pretty dramatic changes in demand for trade transport services, rather than a Zero Sum Game condition that always adds up to the same totals no matter what happens.

This is partly why my proposed quantity scheme above in post #7 relies on exponents (square, cube, quad) to determine daily arrivals/departures, for population numbers that increase on a logarithmic scale.

 

[Condottiere]

Trade is arbitrage, if you can obtain the same or equivalent item elsewhere, at a cheaper price.

In theory, you can then transfer resources, human, financial, and otherwise, to more profitable avenues.

Or, you get a rather pissed off underclass, that require subsidized meals and free entertainment.

 

[TamsinP]

One thing to consider when using our real-world trade flows to model interstellar trade is the difference in how long shipping takes.

From a video I saw yesterday about the impact of ships using the Cape route rather than taking the Red Sea/Suez Canal route.

US Gulf to Asia: 53 days (Suez), 57 days (Cape)

Europe to Asia: 40 days (Suez), 52 days (Cape)

Australia to Europe: 38 days (Suez), 42 days (Cape)


One jump - 9 days
Two jumps -18 days
Three jumps - 27 days
Four jumps - 36 days
etc, etc...

 

[whartung]

Except that's not how things work.
You reach the Zero Sum Game condition once a market is saturated, but not before.
Until that market saturation is achieved, exponential growth is possible (see S-curve adoption rates), which for the purposes of our discussion here can result in some pretty dramatic changes in demand for trade transport services, rather than a Zero Sum Game condition that always adds up to the same totals no matter what happens.

Certainly, but the question is that even with exponential growth, how much of that is actually reflected in interstellar trade at a global level.

Individual markets explode, but we're (me, I'm) talking the gross trade of comparable, stable economies. The premise is that the markets were stable and, essentially, saturated (i.e. the market for cars is only so big in the US and Europe), and being met locally (i.e. on world).

The question becomes how much of the current markets might migrate to interstellar venues.

All trade happens, essentially in a vacuum. That is, there's demand for something that is filled via trade. No doubt those cars from Regina may have some exotic local appeal (none of that Terran made junk for me! I buy imports!), but, as they say: "In Germany, Budweiser is an imported beer."

Clearly it doesn't make much sense that all trade would go interstellar, local still has value, even if the shipping costs aren't that out of line. (Right now, after an extensive, 2s google search, container costs per dton are about 1/2 of 1000Cr per dton jump shipping).

So, in terms of the high level, meta trade market, what's a good dart toss as to percentage of global trade going off planet.

 

[kilemall]

Big part of traffic should be intrasystem, and raw materials to feed whatever industry is at the main world.

But again, must caution most worlds are not Pop 8+ and this is more sailing era economics then SimSpace.

 

[Spinward Flow]

Big part of traffic should be intrasystem, and raw materials to feed whatever industry is at the main world.

Hence why I included J0 as well as J1+ in my proposal.

So, in terms of the high level, meta trade market, what's a good dart toss as to percentage of global trade going off planet.

Interstellar trade is going to be a function of supply vs demand.
Should the mainworld be a net importer or exporter of goods?

Agricultural worlds tend to be exporters (they produce a surplus of foodstuffs) ... and their best markets are going to be Non-agricultural worlds, although an argument can be made that Industrialized and Poor worlds ought to make for good secondary markets.

Non-industrial worlds tend to be both exporters (resource extraction) as well as importers (insufficient local industry/economic diversification).
Same for Industrialized worlds, which tend to be importers (raw materials) as well as exporters (finished goods).

In the interstellar context, you're not going to have a One Size Fits All™ solution to your question, because the DETAILS concerning trading parter worlds in other star systems will be partially dictated by the MAP ... and what kind of import/export demands a world's economy will have.

This is where some of the GURPS Traveller extensions can become useful.
Things like the Friendly/Xenophobia continuum can inform how "open" a world is to interplanetary/interstellar trade.
The Efficiency rating can inform how dependent a world is on exports to sustain the economy (below zero tends to require transfers of capital and goods because the domestic economy is not self sustaining).

In other words, it's perfectly reasonable to have 2 worlds with the exact same UWP codes in different places which will have markedly different volumes of trade going off planet ... simply due to context and local customs/conditions that do not show up in UWP codes.

 

[Grav_Moped]

Or, you get a rather pissed off underclass, that require subsidized meals and free entertainment.

You can have Bismarck, or you can have Robespierre, or something in between.