Is everyone in the Spinward Marches a Rabbit

[aramis]

Armis

I am going to respectfully disagree with you. The cost of supporting 30 billion on imports would be impossible. Looking at Dubai the nearest economy to match this situation they spend 100s of billions and its barley political and economically sustainable. With a population of a few million. So I cant see how this would work out. These numbers are just ridicules based on some random generation without editor oversight.

Dubai has very little of value - they're tiny, and thus have very little of the Mid-East oil - but they're rapidly growing a huge tourism industry. And, between oil and tourism, they're one of the wealthiest economies in the middle east.

It can be very practical to be a net importer if one can come up with low volume, high value resources. A Zucchai Crystal mine could easily support it. Or, it could be a buried moisture world of hive cities...

And, with fusion power, relatively safe fission power, and high-tech engineering, it's entirely possible to have much denser, not visible on surface, artificial environment farms... something I should have thought of earlier, but was distracted.

Envision a warren of subterranean geothermal and nuclear powered hydroponic and aeroponic farms.

There's no reason people need to live on the surface, either.

 

[Timerover51]

Which simply means it must needs be a net importer from somewhere. Perhaps from other worlds in system, perhaps from out-system, perhaps from orbital farms.

The US military assumes that the average service member requires approximately 6 pounds of food per person per day. That allows for wastage, and does assume about 3,600 calories per person. Projecting that over a large population, assuming that for the most part the population is sedentary, and allowing for increased consumption for pregnant mothers and those non-sedentary workers, and the nutrition requirements of growing children, you might get that down to an average of between 4 and 5 pounds a day. Using an average figure of 4.5 pounds, that would equate to approximately 1600 pounds of food per year per person. That is about .75 metric tons per person per year. That would put the food requirements of Rethe at a minimum of 22.5 Billion metric tons of food per year.

Studies done by NASA for orbiting space colonies included the use of farms within the colony to supply food. Under ideal growing conditions of 24 hour daylight, CO2 enriched air, and continuous hydroponic water and fertilizer supply, the assumption was that one acre of orbital farm could feed potentially 30 people, albeit a pretty monotonous diet. A more varied diet would give a yield per acre of orbital farm of sufficient food for 10 people per day continuously. If Rethe is producing 1/3 of its food, and the other 2/3 is supplied by orbital stations, at 6.400 people fed per square mile of farm, the area required would be 3,125,000 square miles. The total land area of the US is 3,538,800. That is a lot of orbital farms. For that many, a starport of E does not seem appropriate. And if you land One Million tons of food a day at the starport, you would supply 1.6% of the yearly needed food supply.

As Rethe has a very thin atmosphere and a Zero hydrographic percentage, so between 0% and 5%, I would view it as doubtful that it is supplying sufficient food for 10 Billion people out of its own resources. For that matter, using standard military water consumption rates for an established base of 50 gallons per person per day, the population would require 1,500 Billion gallons of water per day. That equates to a 1.36 cubic miles of water per day, or 496 cubic miles of water per year. The Great Lakes of the US contains about 5,400 cubic miles of fresh water. Now the 50 gallon per day value is conservative, as for urban planning purposes, a usage of 200 gallons per person per day is assumed. That would give a usage rate of 1,984 cubic miles per year. The Great Lakes would last about 3 years.

You have a very thin atmosphere which means a low vapor pressure for exposed water, and a high evaporation rate. That would mean that a lot of the water used is going to be lost into the atmosphere, and not available for further usage. Also, in order to grow crops you will need some means of compressing the atmosphere into large green houses, presumably domed to compensate for the difference between inside and outside pressure. Overall, I would say that water is going to be as big, if not bigger, a problem as food will be on Rethe, along with supplying pressured breathable air to the population. Considering that you would need to have a closed circuit ecology system for 30 Billion people, a Tech Level of 8 does not seem appropriate at all.

Rethe is one of those worlds that I simply assign a population exponent of 4 too, and assume that a very valuable resource exists to justify that many people.

 

[Timerover51]

And, with fusion power, relatively safe fission power, and high-tech engineering, it's entirely possible to have much denser, not visible on surface, artificial environment farms... something I should have thought of earlier, but was distracted.

Envision a warren of subterranean geothermal and nuclear powered hydroponic and aeroponic farms.

There's no reason people need to live on the surface, either.

Several million square miles of hydroponic farms, along with several million square miles of inhabited area. Interesting. And all subterranean.

 

[far-trader]

For that matter, using standard military water consumption rates for an established base of 50 gallons per person per day...

Is that including showering, bathing, and the biggest waste toilet flushing? And I think you're overlooking recycling of the water. High tech is going to mean you don't need as much water and what you do use will be almost entirely recycled. Especially if the environment is a closed one. You won't need to import nearly that much to maintain the system, and you can probably do it easily with a few ice body or gas giant skimming tankers.

 

[rancke]

Is that including showering, bathing, and the biggest waste toilet flushing? And I think you're overlooking recycling of the water. High tech is going to mean you don't need as much water and what you do use will be almost entirely recycled. Especially if the environment is a closed one. You won't need to import nearly that much to maintain the system, and you can probably do it easily with a few ice body or gas giant skimming tankers.

It's not just high tech, it's ultra-tech (two terms I've begun promoting are 'ultra-tech', beyond what we have on Earth today and up to Imperial maximum (i.e. from 8-15), and 'hyper-tech', beyond Imperial technology, 16 and up). With cheap fusion power, enclosed habitats with self-sustaining hydroponics and carniculture to feed people are entirely possible (but as the infrastructure is more expensive, they are rarer).

My own (non-canonical) picture of Rethe is as the gravitational anchor for orbital habitats and source of minerals. Few people actually live ON Rethe.

As for water, human metabolism create water, so in an enclosed system the problem is getting rid of it.


Hans

 

[rancke]

Studies done by NASA for orbiting space colonies included the use of farms within the colony to supply food. Under ideal growing conditions of 24 hour daylight, CO2 enriched air, and continuous hydroponic water and fertilizer supply, the assumption was that one acre of orbital farm could feed potentially 30 people, albeit a pretty monotonous diet. A more varied diet would give a yield per acre of orbital farm of sufficient food for 10 people per day continuously. If Rethe is producing 1/3 of its food, and the other 2/3 is supplied by orbital stations, at 6.400 people fed per square mile of farm, the area required would be 3,125,000 square miles. The total land area of the US is 3,538,800. That is a lot of orbital farms. For that many, a starport of E does not seem appropriate. And if you land One Million tons of food a day at the starport, you would supply 1.6% of the yearly needed food supply.

I agree that Rethe has to be an extreme case, quite probably tottering on the brink of collapse. For one thing, the tech level is only 8. However, some technologies could be in advance of the High Common, so TL9 fusion power plants are possible.

As for the starport class, here's my explanation (from a JTAS Online article, so not canon):

"bout a generation ago, Rethe's population experienced a 'baby boom' and began growing explosively. The growth spurt is tapering off now, but in the last 30 years the population has grown by almost seven billion. The citizens have been struggling to cope with the population increase, building more orbital habitats and other needed infrastructure, putting a tremendous strain on all space activities. At one point visiting starships could not expect to get any service at all, at least not in a timely manner. Things are improving now and the starport will soon be reclassified to Class III and eventually back to its original Class IV status."​

Hans

 

[mike wightman]

No one mentioned artificial wombs and in-vitro fertilization yet?

We know that the Imperium practices genetically altering colonists, so tank growing a few million shouldn't be a problem.

 

[rancke]

No one mentioned artificial wombs and in-vitro fertilization yet?

We know that the Imperium practices genetically altering colonists, so tank growing a few million shouldn't be a problem.

No indeed. But it's not necessary to explain the canonical population figures.


Hans

 

[Ishmael]

water usage ( on earth ) indicates that far far more than 50l per person is needed.
Personal use, which includes drinking/bathing/etc., only accounts for about 8% of the total water used by humans.

~91% of the water used is for agriculture (~69% ) and industrial (~22%) use. It takes about 3000l of water to grow the food to feed a man for one day. One chip fab plant of IBM creates ~8,000,000l of ultra pure water per day.

Imagine the costs to Rethe if they had to pay to build the underground facilities using the tunnelling costs for building planetoid ships and someone had to pay all life support costs for each citizen for the life of the citizen.

Of course, bringing up canon descriptions of Roup opens other cans of worms due to food scarcity and tech levels.

Just accept that the populations and their distribution are purely random without any considerations for environment that affect real populations.

 

[rancke]

Water usage ( on earth ) indicates that far far more than 50l per person is needed. Personal use, which includes drinking/bathing/etc., only accounts for about 8% of the total water used by humans.

Since the water would be recycled, it doesn't matter much (except to the size of the recycling infrastructure).

Imagine the costs to Rethe if they had to pay to build the underground facilities using the tunnelling costs for building planetoid ships and someone had to pay all life support costs for each citizen for the life of the citizen.

The classic way to cut down tunneling costs is to use natural caverns and exhausted mines. The cost of space habitats are presumably comparable to the cost of building ships, but the people of Rethe would have had a millenium to come up with the money. Life support for habitats are evidently far less than for ships. (See description of Leedor in TTA; apart from a very modest air tax there is no mention of increased living expenses).

Note that thousands of worlds (asteroid belts and airless worlds) have the very same costs of living. Some presumably have worse (worlds with corrosive and insidious atmospheres (though I do tend to place a lot of the population of such worlds in orbit).


Hans

 

[Fritz_Brown]

linking population growth rates to population density can make things interesting for worlds of differing sizes, especially when you work out what the population's extinction threshold might be for use in determining Allee effects.

Naturally, this growth rate is fed into a log model of growth for a nice sigmoid curve when carrying capacities are considered.

Another idea might be to look into a world3 model.
http://en.wikipedia.org/wiki/World3
http://world3simulator.org/

Could you put that in Captain dummy-talk, please?

I would expect most of the Traveller universe to have growth rates on this order, except for more frontier planets. With that sort of growth rate, in 1,000 years the population would increase by a factor of 8.312.

That assumes a constant growth rate, timerover. The numbers you cite are for a year-to-year rate, but that rate can change drastically over 1,000 years.

These numbers are just ridicules based on some random generation without editor oversight.

You hit the nail on the head there. The biggest problem with any of the numbers (but especially the human-centered ones) in the UWP is that they are pseudo-randomly generated, and you really have to give them a sanity check before putting them out there. There are ways to generate much more believable numbers, but it would require a computer program and wouldn't fit in a LBB.

water usage ( on earth ) indicates that far far more than 50l per person is needed.

The amount quoted above was 50 gallons, so almost 4x what you state. And that 3,000l amount for growing food (on a per-day basis!) seems a wee bit high.

Recycling works when you have plenty of cheap energy, but there still is some loss to waste. The numbers for that world are probably unrealistic without a lot of handwavium.

 

[Ishmael]

Since the water would be recycled, it doesn't matter much (except to the size of the recycling infrastructure).
-------------
The classic way to cut down tunneling costs is to use natural caverns and exhausted mines. The cost of space habitats are presumably comparable to the cost of building ships, but the people of Rethe would have had a millenium to come up with the money. Life support for habitats are evidently far less than for ships. (See description of Leedor in TTA; apart from a very modest air tax there is no mention of increased living expenses).

Note that thousands of worlds (asteroid belts and airless worlds) have the very same costs of living. Some presumably have worse (worlds with corrosive and insidious atmospheres (though I do tend to place a lot of the population of such worlds in orbit).

There is always infrastructure whether its wells and piping to water treatment plants. The infrastructure still must be paid for and maintained. Presumably, life support costs would cover this and 10% maintenance costs each year.

Tunneling costs are still required for the exhausted mines' initial costs. Caverns would either be old magma chambers, lava tubes or similar...all bad places for construction. The stereotypical caverns with stalagmites/stalactites occur in limestone; not only do the formations require that there were once large flows of water present, but the limestone itself means that there had been life in the past in addition to water, given the origin of limestone. This may be problematic in some world descriptions; Rethe would have to explain where all the water went if there were large limestone deposits present.
Even though the initial construction costs may have been paid far in the past, the 10% maintenance costs would still have to be paid. This, is major governmental expenditure which is somehow rarely accounted for in canon materials.

Leedor is a bad example for the position that "Life support for habitats are evidently far less than for ships." It is a single data point and there are more explanations for what the 'air tax' is. It may simply be a discretionary tax ( which in PE leads to lower popularity of the government ) and that the regular tax expenditures cover the costs of the life support and infrastructure maintenance. Such a discretionary tax may be needed to cover those costs in addition to Imperial taxation, military, etc.

That 'thousands' of asteroid belts/airless worlds/orbital space stations have the same life support costs should be no surprise as they all have to provide the same level of life support per person, but nowhere is that cost actually discussed. 'Thousands' is a bit of hyperbole, though, especially when very few have been visited in any amount of detail.

As I said before, just accept that populations are random and improbable, then rationalize them how you wish in ytu.

 

[rancke]

There is always infrastructure whether its wells and piping to water treatment plants. The infrastructure still must be paid for and maintained. Presumably, life support costs would cover this and 10% maintenance costs each year.

So must the infrastructure costs of life on the surface of a Human-norm world. The question is how much more the costs are for a space habitat and whether people can make a good enough living to pay them. As the various airless worlds all around the OTU shows, they can.

Tunneling costs are still required for the exhausted mines' initial costs.

But that has been paid out of the mine's operating expenses back when it was making a profit.

Caverns would either be old magma chambers, lava tubes or similar...all bad places for construction.

If it was good enough for Heinlein, it's good enough for me.

Leedor is a bad example for the position that "Life support for habitats are evidently far less than for ships." It is a single data point and there are more explanations for what the 'air tax' is. It may simply be a discretionary tax ( which in PE leads to lower popularity of the government ) and that the regular tax expenditures cover the costs of the life support and infrastructure maintenance. Such a discretionary tax may be needed to cover those costs in addition to Imperial taxation, military, etc.

There's also the evidence of the existence of numerous airless worlds with populations that has to be living in habitats.

That 'thousands' of asteroid belts/airless worlds/orbital space stations have the same life support costs should be no surprise as they all have to provide the same level of life support per person, but nowhere is that cost actually discussed.

But it's earnable. If it wasn't, people wouldn't be able to live in habitats.

'Thousands' is a bit of hyperbole, though, especially when very few have been visited in any amount of detail.

The only detail that we need is the amount of air around, and I think 'thousands' hits the mark pretty well.

As I said before, just accept that populations are random and improbable, then rationalize them how you wish in ytu.

If it's all the same to you, I prefer to muddle on trying to rationalize some of those improbable populations. I actually agree with Marc Miller that the process of justifying odd UWPs can lead to some fascinating settings. I disagree with him that it is possible to come up with an explanation for every conceivable UWP, but so far I haven't given up on Rethe.


Hans

 

[mike wightman]

Just because Rethe is TL8 it doesn't mean that TL12+ technology couldn't have been used to construct underground arcologies.

The O'Neill habitats I linked to earlier (but in a different thread - d'oh) would be a challenging construction project at TL8, but build them at TL12+ to be maintained at TL8 and it becomes trivial.

Rethe is a desert world, a source for the canonical dust spice perhaps?

 

[Ishmael]

So must the infrastructure costs of life on the surface of a Human-norm world. The question is how much more the costs are for a space habitat and whether people can make a good enough living to pay them. As the various airless worlds all around the OTU shows, they can.

All it shows is that the population generation is random without concern for how the environment can affect populations' viability.

But that has been paid out of the mine's operating expenses back when it was making a profit.

of course, but maintenance costs are base on original purchase costs and that is what has to be paid yearly now.

If it was good enough for Heinlein, it's good enough for me.

In Heinlein's story, was the planet smaller and cooled to the point of being tectonicly dead? Or was it larger and still active.

There's also the evidence of the existence of numerous airless worlds with populations that has to be living in habitats.

Of course living in habitats, but without any mention of how those habitats are paid for or maintained.
And it is still evidence that the population is random without care for how environments affect viability.

But it's earnable. If it wasn't, people wouldn't be able to live in habitats.

Do you know that as a fact? or is it something you just feel is true. Without a reasonable economic base for the OTU, how can you tell?

The only detail that we need is the amount of air around, and I think 'thousands' hits the mark pretty well.

A detail you gave when you stated "...thousands of worlds (asteroid belts and airless worlds)" which I took to mean , well... thousands of asteroid belts and airless worlds, so, no air...vaccuum. IMHO, the UWP procedure for atmosphere is bad as well, but that's a different thread topic.

If it's all the same to you, I prefer to muddle on trying to rationalize some of those improbable populations. I actually agree with Marc Miller that the process of justifying odd UWPs can lead to some fascinating settings. I disagree with him that it is possible to come up with an explanation for every conceivable UWP, but so far I haven't given up on Rethe.

That's fine with me although I think there is a limit on how far a justification can stray towards fantasy.

 

[HiverLord]

FWIW, an old accounting 'trick' someone taught me a long time ago is the Rule of 72. (This popped back into my head while reading this thread. And no, I'm not an accountant. )

Divide 72 by the percentage rate of increase for a time period (say years, for example). This gives you the number of that time rate for the base number to double.

So, if you start with a pop of 2000 experiencing a growth rate of 5% per year, they'd double their population in about 14.4 years or so. (Of course, this only tracks growth, not declines for any other reasons.)

Thought someone might find this useful (assuming I described it correctly; if not, I'm sure someone will correct me.)

 

[aramis]

Someone asked for "captain dummy" speak...

Logarithmic curve: The further it grows, the faster it grows. Doubling curves are logarithmic (base 2 log)... 1 doubles to 2, doubles to 4, to 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 711072 etc...

Each full step in a logarithmic curve is a multiplication of the base... so in a base 1.1 log,
the 0th step is 1, the 1st is 1.1, the second is 1.1^2, the third 1.1^3, the fourth 1.1^5... and so on.

And generally, at some point, log based curves appear nearly vertical...

 

[77topaz]

Someone asked for "captain dummy" speak...

Logarithmic curve: The further it grows, the faster it grows. Doubling curves are logarithmic (base 2 log)... 1 doubles to 2, doubles to 4, to 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 711072 etc...

Each full step in a logarithmic curve is a multiplication of the base... so in a base 1.1 log,
the 0th step is 1, the 1st is 1.1, the second is 1.1^2, the third 1.1^3, the fourth 1.1^5... and so on.

And generally, at some point, log based curves appear nearly vertical...

Isn't that an exponential curve? o:
(Wouldn't a logarithmic curve be that flipped diagonally, with the growth rate decreasing?)

 

[Ishmael]

The exponential growth curve is bounded by carrying capacity.
The growth rate per capita is related to population density.

r is the growth rate per capita and is affected by population density. Generally, this goes down as density goes up due to competition for resources. In some cases, it can go up as density increases where cooperative behaviour allows for increased growth rates.
K is the carrying capacity which is the total number of individuals that an environment can support.
N is the population

A is the critical threshold below which growth increases with density. In some cases, it is the extinction threshold.

As you can see, as density increases, population growth slows.
As population approaches carrying capacity, growth slows.
If population goes over the carrying capacity, there will be die-offs or emigration.

To just say that populations grow exponentially without mentioning bounds only tells part of the story.

btw, the game's usual way of handling 'pop mod' fails Benford's Law

 

[DangerousThing]

I have a couple questions. The people in this note are extremely long-lived and are in extremely good health. They can potentially live for over a thousand years, are resistant to most diseases, and can heal from most wounds quickly. They do require about twice the food of a baseline human.

The event I'm talking about almost destroyed star travel effectively over the galaxy, with the exception of a few random ships which became traders or raiders.

Except for a few ships far away from all planets at the time, the Shattering destroyed all computer equipment, media, and most TL 8+ electronics.

1. After the first winter only about 500 had survived in the main settlement, how long would it take to breed to over to over 10,000,000? I am making the assumption that this is a major project and that the women are willing to have 12 children or so (one child every other year until they can support more with agriculture), then wait for twenty years or so, then have nore children). There would be record keeping and enforcement for maximum genetic diversity until this wasn't necessary. For maximum efficiency there would be communal child care

2. How many people would it take to develop a TL 12 society?

When talking about a TL 12 society, the people need space defenses, a navy, and trade. They're willing to have lower tech for most day to day things.

There is a twelve world confederation doing this, though at first communication is limited until they can start building jump ships of their own.