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Old 07-25-2007, 12:39 PM   #11
balzacq
 
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Default Re: [Space] How habitable is my universe?

I have a PHP script to generate systems as per GURPS Space, with a very few minor tweaks (Agemegos' revised tidal formulae and aging the system in 0.1Gy blocks to track changes over stellar evolutionary timescales). I use the chart in G:S to generate stellar types instead of real-universe data. Also, I use all the rules except for brown dwarf and flare star generation.

I've generated a total of 16977 systems this way (I have a perl script that creates whole thousand-system sectors at once). The habitability breakdown is as follows:
Code:
Hab.   Systems    %
8  	136  	0.80
7 	300 	1.77
6 	257 	1.51
5 	338 	1.99
4 	303 	1.78
3 	180 	1.06
2 	105 	0.62
1 	28 	0.16
0 	15317 	90.22
NULL 	13 	0.08
(Without diving into the tables right now, I suspect that the NULL values are from systems with nothing but gas giants and belts.)

I'm at work and without my books, but I was under the impression that you didn't even generate carrying capacity for Hab 0 planets -- the assumption was that Hab 0 systems would only ever have outpost-type residents (miners, military, etc.).
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Old 07-25-2007, 01:55 PM   #12
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Default Re: [Space] How habitable is my universe?

Quote:
Originally Posted by Agemegos
The Affinity Modifiers Table on p.91 gives carrying capacity multipliers for affinities down to -5. And the maximum RVM is -5 (-3 for worlds that are not asteroid belts), implying non-zero carrying capacity on worlds with habitability -2.
I am perhaps confusing the population rules in Space with those in GT: Interstellar Wars.
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Old 07-25-2007, 07:57 PM   #13
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Default Re: [Space] How habitable is my universe?

Quote:
Originally Posted by Agemegos
So do I. But my capacity to do this fails when faced with a massively contingent system like this.
Which is why I haven't done it, either.

Quote:
It's the Anna Karenina Principle. There is only one way to be spot on the ideal, but as for being off by one category in one dimension, there are twice as many possibilities as dimensions...

Some sort of extreme-value distribution, maybe? The thing is that we aren't looking as a measure but an index.
Yes and no. The range for each variable is already constrained because we're necessarily talking about habitable worlds. As long as the bins are wide enough, the combinations will still result in a jackpot fairly frequently.

Quote:
But what we have got takes that metric and chops it range up into a bunch of unequal-width bands, with the central peak somewhere in the category called 'habitability 0'.
I don't think so, unless I missed something important.

What we have is two categories -- hostile (habitability 0) and habitable (habitability >0) -- with a probability function to choose between them, e.g. f(0) = 0.9. Within the habitable category, there is a roughly bell-shaped distribution of habitability with a central peak defined by how wide are the bins (i.e., how likely are the optimum results) in each variable.
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Old 07-26-2007, 07:07 AM   #14
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Default Re: [Space] How habitable is my universe?

Quote:
Originally Posted by Agemegos
I'm not necessarily talking about habitable planets. A lot of the time the highest 'habitability' score in a system comes from a planet with suffocating atmosphere, no water, and unendurable temperatures.
Hmmm. On review, you're right. This is a significant departure from earlier uses of "habitability," and a flaw in the system in my opinion. I don't see the point of discussing or measuring the "habitability" of any world which cannot support human life in the open somewhere on its surface. Sealed habitats and life support are pretty much the same, no matter where one goes, and it's pointless to assign them a "natural" carrying capacity.

As for worlds with Toxic or Corrosive atmospheres, the answer is that one would not "colonize" them at all, when it would be simpler and safer to construct an orbital habitat or one on a nearby asteroid or moon. If there were valuable resources to exploit or interesting aliens to contact, one would build an outpost instead, which does not depend on carrying capacity (p. 93), and support it from a colony somewhere more convenient.
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Old 07-26-2007, 06:51 PM   #15
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Default Re: [Space] How habitable is my universe?

Quote:
Originally Posted by Agemegos
Quote:
Originally Posted by TheDS
Well, if it's a system sheet, you need system data. The central star's characteristics, if it has companions, then you need their characteristics and orbital info. Then you need to know orbital slot info (forbidden zones, snow limit, hab zone, orbit slot distances, etc).

I disagree. You need to calculate the forbidden zones and snow line and so forth to generate the system, but once the system is generated you don't need to display them. The same goes for the habitable zone, empty orbits, etc. Where a planet might have been, what areas a planet might be warm enough to be habitable if were there but it isn't—these aren't things that matter to characters in the setting, or that explorers in the setting observe, and they aren't going to appear in the Popular Handbook of the Planets.
Ah, of course, you're right. I'm just the kind of guy that likes to know that kind of stuff, I suppose for "error checking" purposes or what have you, but it shouldn't be in the final output. My bad.

When it all comes down to it, information about the star system is mostly irrelevant anyway; that's pretty much why most Traveller maps show only the main world's name, whether it's high pop, and the fueling, repairing, and trading possibilities. If you're looking to map out an unexplored section of space, you want to know spectral type to help narrow down where good worlds are more likely to be (and how far from the sun to look for them), and if you're in charge of sending out colony ships and have to make a report to the Emperor, you're not going to show him tons of details, you're going to show him a few pieces of information and ask him to point to the ones he wants colonized.

Or something like that.
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Old 07-27-2007, 08:41 AM   #16
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Default Re: [Space] How habitable is my universe?

Quote:
Originally Posted by Agemegos
I agree. It is a flaw.
I have a nice example now that I have tidal locking fully implemented. I'm getting tide-locked planets that have no water whatsoever because it is all frozen out on the dark side. These ought to be completely uninhabitable, but they are coming out with habitability ratings of 3 and 4, even 5, because the habitability table can't assign a negative-infinite modifier for zero water coverage. In theory a tide-locked world with no liquid water can have Habitability 6.
.
Why is that so bad ? Such a world would have a breathable atmosphere and temperate climate. The water may be frozen, but you only have to get ice to warmer areas to have sunshine melt it. That´s a lot better than what we have on mars for example.
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Old 07-27-2007, 11:47 AM   #17
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Default Re: [Space] How habitable is my universe?

Quote:
Originally Posted by thrash
Hmmm. On review, you're right. This is a significant departure from earlier uses of "habitability," and a flaw in the system in my opinion. I don't see the point of discussing or measuring the "habitability" of any world which cannot support human life in the open somewhere on its surface. Sealed habitats and life support are pretty much the same, no matter where one goes, and it's pointless to assign them a "natural" carrying capacity.
It's not totally pointless; which resources and hazards are present in the environment makes a big deal on how challenging life support is.
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Old 07-27-2007, 07:01 PM   #18
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Default Re: [Space] How habitable is my universe?

Quote:
Originally Posted by Agemegos
The cases that I am complaining about...If it tide-locks....But its habitability is 4.
Is Habitability calculated before or after length of day?
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Old 07-28-2007, 09:04 AM   #19
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Default Re: [Space] How habitable is my universe?

Quote:
Originally Posted by Anthony
It's not totally pointless; which resources and hazards are present in the environment makes a big deal on how challenging life support is.
Is raw vacuum in orbit "habitable"? If not, then assigning a "habitability" rating to worse conditions is pointless.

My objection is that GURPS Space 4/e altered the commonly accepted definition of "habitable," one that has been used consistently in previous SJ Games products. "[A] summary of all the factors that make a world pleasant to live on," should, in fact, imply that it is even possible for humans to live on the world, as opposed to in artificial habitats that happen to be located there.

The proper place to include the relative difficulty of living on uninhabitable worlds is in the calculation of affinity. GURPS Space 4/e unnecessarily confuses the two.
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Old 07-29-2007, 08:58 PM   #20
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Default Re: [Space] How habitable is my universe?

Dumb question time:

Could the Hab rating be the best you can make it with the aid of some terraforming, rather than the way you found it? I mean, it seems to me that the Hab4 ball just described could have an atmosphere built and regenerated, and the humans inhabit it on the twilight edges. Sure, the atmosphere escapes over time, but that's not a problem for anyone currently alive.

With the twilight band having a tolerable level of atmosphere and heat, maybe in a few hundred years some of the day heat will transfer over to the night side and release the water. So long as the atmosphere-making machines are running, it could become a regular, habitable, tide-locked world, up to whatever Hab4 means.

The alternative seems to be then, that there are even fewer habitable worlds.
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