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 Post subject: Architect of Worlds
PostPosted: Fri Aug 16, 2019 4:08 pm 
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Newish project by Jon Zeigler of GURPS Space and First In.

http://sharrukinsarchive.com/index.php/ ... ect-worlds

Looks like he hasn't worked on it in a while, which is a shame. The proposed TOC looks terrific.


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 Post subject: Re: Architect of Worlds
PostPosted: Sun Aug 18, 2019 10:49 am 
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Jon Zeigler is also one of the authors, and designer of the star system and planet generation sequences in, GURPS Space (4th edition). I really hope that he soon finds himself secure and stable enough to resume work on Architect of Worlds. But I think (and have said to Jon) that I think the day of system design algorithm that is executed by hand with a pencil, form, and dice has passed, and that the amount of precision and detail tha he is going to be able to achieve in a modern design system calls for text and an app instead.


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 Post subject: Re: Architect of Worlds
PostPosted: Tue Dec 22, 2020 12:02 pm 
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Update: He's been busy these last couple years. Accretion disks, Gas giant migration, lithosphere types...

Everything up to 2019 is in pdfs, and the newer content (he just posted surface water) you have to sift through the blog to get.

It's quite a process, and I would absolutely write up a script to manage it.


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 Post subject: Re: Architect of Worlds
PostPosted: Tue Dec 29, 2020 9:50 am 
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There is a complete draft text now.


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 Post subject: Re: Architect of Worlds
PostPosted: Thu Dec 31, 2020 10:35 am 
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I've reviewed Jon Zeigler's preliminary draft and sent him a first tranche of comments. As soon as I get a replacement for my two defunct scientific calculators I'll run the sequence a couple of times and provide more comments.

Compared with his previous effort (the Basic and Advanced star system generation sequences in GURPS Space 4th) the planetary science has been substantially brought up to date, reflecting fifteen years of rapid scientific discovery. There has been a significant extension of scope in that the generator now produces a detailed composition of the atmosphere. I am impressed that it takes care to make the greenhouse effect on the planet's surface temperature consistent with the greenhouse forcing values of the minor constituents of the atmosphere.

On the other hand the "Basic" approach (design or generate a planet to taste, calculate its orbital position, and then generate the rest of the system around it) has gone. The new system has achieved a large part of its streamlining by leaving out the tidal calculations and reducing the calculation of tidal braking to a sketch. It also omits the effects of tidal locking on the temperature and volatiles of the day and night sides, though perhaps that will return in a later draft.

Most of the additional work and detail has gone into the developmental process of the star system: mass of the protoplanetary disk, degree of orbital migration of the key gas giant, whether there has been a Grand Tack, whether one of the primordial gas giants was expelled from the system by orbital shenanigans…. It does inform the outcome, but I wonder whether it would not be better to roll on a table of outcomes in terms of overall system architecture and save the user's patience for detailed surface conditions on habitable planets. Apart from the composition of the atmosphere (which has been done), the extensions that I wanted to see were
  1. provision for generating systems around real nearby stars, using data from astronomical catalogues that usually lack figures for mass, age, and metallicity,
  2. the illumination level,
  3. the boiling point of water at the surface,
  4. the salinity of the oceans,
  5. the scale height (or half height) of the atmosphere,
  6. the altitude limits of respiration,
  7. the effect on aircraft operational ceilings,
  8. the practical minimum altitude of a circular orbit, with the corresponding orbital period,
  9. the surface relief — how high are the mountains and plateaux?,
  10. the number of convectional cells in the global atmospheric circulation, the zonal wind strength, and the vorticity — word scales ("low", "exreme" etc.) would do,
  11. the temperature of the thermal equator (or subsolar point) and polar regions (or terminator and night side),
  12. the equator-ward and pole-ward (or subsolar-point-ward and terminator-ward) limits of agriculture.
As a GM or writer of planetary adventure I'm more interested in "Where on this planet do people live; can they make good coffee?" and less in orbital migration five billion years ago, than I am as an amateur of modern astronomy.

Is that too much figuring-out to expect for someone working with a pencil, paper, a handful of dice, and a scientific calculator? Yes, perhaps it is. But that gets us back to what I said in my first comment in this thread. Jon Zeigler's Architect of Worlds is going to be distributed as a PDF. Everyone who reads it is going to have a computer right there. They would get much more use out of a program or interactive website than they would out of an algorithm for manual execution.

I hope that I have already bought my last petrol-burning car. I'm pretty sure that I have bought my last star-system generator for use with dice and calculator.


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 Post subject: Re: Architect of Worlds
PostPosted: Wed Jan 13, 2021 7:00 pm 
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Quote:
the altitude limits of respiration


His notes on PPO tolerances seem a little... off. Unless the text has been updated, he says a respirator is required at a PPO below 19.5, citing some OSHA regulations. But I think the population of Denver might take issue with that position. I didn't want to push the argument on his blog, but you can handle a lot less oxygen via a gradual transition.


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 Post subject: Re: Architect of Worlds
PostPosted: Thu Jan 14, 2021 2:00 am 
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Matt Wilson wrote:
Quote:
the altitude limits of respiration


His notes on PPO tolerances seem a little... off. Unless the text has been updated, he says a respirator is required at a PPO below 19.5, citing some OSHA regulations. But I think the population of Denver might take issue with that position. I didn't want to push the argument on his blog, but you can handle a lot less oxygen via a gradual transition.

Yeah. I wrote to him pointing out that three entire states of the USA are uninhabitable by that standard, and that there is a city in Peru where people live in 0.115 bar of oxygen and work in 0.111 bar. I mentioned, too, that 0.3 bar of oxygen is known not to produce any toxic effects in medical settings (though 0.5 bar does). He replied that he will look into it.

That was a bit of a research failure.


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 Post subject: Re: Architect of Worlds
PostPosted: Tue Jan 26, 2021 4:14 pm 
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The main problem is that OSHA sets their standards on percentage, since that's what almost all oximeters use, and there's no consideration for altitude. But they're driven by workplace safety, and absolutely if the air reads less than 20% oxygen it's a red flag (find a player character who would stay in that room a second longer). But that's an entirely different concern.

By the way, you might appreciate this pressure/altitude calculator if you haven't already found it.


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 Post subject: Re: Architect of Worlds
PostPosted: Tue Jan 26, 2021 7:49 pm 
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Matt Wilson wrote:
The main problem is that OSHA sets their standards on percentage, since that's what almost all oximeters use, and there's no consideration for altitude. But they're driven by workplace safety, and absolutely if the air reads less than 20% oxygen it's a red flag (find a player character who would stay in that room a second longer). But that's an entirely different concern.


Right. In fact, I found a letter in which the OHSA said explicitly that their standard applies to percentage and not to partial pressure. You get information that is much more useful from some sort of reference about altitude sickness (for low oxygen conditions) and from the toxicity of oxygen in medical use.

Quote:
By the way, you might appreciate this pressure/altitude calculator if you haven't already found it.


That’s handy for Earth. But for some funny reason it doesn’t seem to handle different gravities and atmospheric compositions with different average molecular weight. Fortunately the formulas for scale height and for pressure as a function of base pressure, altitude, and scale height are easy to find and not too bad to use if you have a calculator.


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 Post subject: Re: Architect of Worlds
PostPosted: Wed Jan 27, 2021 1:15 am 
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As a test exercise for Architect of Worlds I have reverse-engineered the Tau Ceti system (including the small terrestrial world in the habitable zone that is predicted by Dietrich & Apai (https://arxiv.org/abs/2010.14675). Ugh! This is tedious! I am confirmed in my conviction that such a generator, based on dice, pencil and paper, and a calculator, is obsolete in the face of computerised generators.


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