I’ve just pushed a copy of the slides I’ll be using on Saturday, 22 November, for a seminar at Philcon 2025. The title is “Foundations of Worldbuilding: Getting the Astronomy Right,” and it’s a quick review of some recent results from exoplanetary science and the GAIA astrometry mission. Feel free to pull down a copy of the PDF for yourself.
I have a contract in hand for this project, and the design is starting to come together nicely (although there is a ton of work to be done), so it’s about time that I pulled the tarp off of it.
As of this month, I’m working on (part of) a new book, with the working title of Symphony of Cultures. This is conceptually a “sequel” to Architect of Worlds, and it’s essentially going to be a book of tools and design sequences for building alien species and alien cultures for interstellar fiction. Ad Astra Games will be publishing it. The objective is to have it ready for release in about a year, in time for next summer’s big conventions. We’re aiming for a book that’s about the same length and heft as Architect of Worlds – that is, about 192 pages of rules, worksheets, and scientific/historical/literary background.
I’m not the sole author for this one. Ken Burnside intends to write at least a short section. We also have a third collaborator who has both gaming chops and considerable relevant expertise in evolutionary biology – honestly, they’re likely to end up writing more of the final draft than I do.
Prior art that might be relevant includes the various Traveller animal-design rules, the old Digest Group Publications release Grand Census, the alien-design rules in GURPS Uplift, and the Civilization tabletop and video game franchises.
The intention is to have a “short” design sequence, something a writer or gamer could complete in an hour or two, generating a “planet of the week” for a piece of fiction. There’s also going to be a “long” design sequence, that would take a lot more work but would help the reader generate the whole evolutionary and cultural history of an alien society in detail. That “long” sequence is where a lot of the scientific and historical mojo is going to be applied.
At the moment I’m drafting an initial design for a major portion of the “long” design sequence, and giving some thought to what the “short” sequence might look like. I’m hoping we can actually start writing big chunks of material by this fall. We may be looking for beta readers and “playtesters” at some point, so feel free to drop me a line if you might be interested in that. I probably won’t be posting portions of the draft here, as I did during development of Architect of Worlds. We’re on a much shorter development cycle for this one, and it has a publisher from day one, so we’ll be working through Ad Astra’s usual playtesting pipeline.
Should be an interesting project, though, and I’m looking forward to making it come together.
It took us a lot longer than it probably should have – I can attest that other things kept grabbing higher priority – but Ad Astra Games and I have agreed on a general policy for anyone who would like to build a computer application to implement some or all of the Architect of Worlds design sequence.
The policy is sitting in my Google Drive, at this link. Ken Burnside and I have agreed on what’s in this document.
You’ll notice that Ken is interested in hosting a full implementation of Architect of Worlds on the Ad Astra Games site, as a convenience for writers and gamers who might want to use the design sequences without having to plow through the book by hand. Developers who would like to talk to Ken about submitting a design proposal are welcome to email him at Ad Astra Games – be sure to use the subject line “Architect of Worlds Automation Design Proposal.”
I’ve just published a PDF document to my Kofi page, free for current subscribers:
Notes on the Structure of Interstellar Civilizations
This is a collection of assumptions, a bit of mathematical modeling, and lots of commentary on the prevalence of interstellar cultures in the Human Destiny setting. Even if you’re not interested in that setting per se, it may be of some interest as an example of deliberate world-building on a very grand scale.
There’s going to be a follow-on project, involving making some maps of the Human Protectorate’s primary volume, and of the immediate galactic neighborhood around Sol in the Human Destiny universe. Not sure if I’ll turn to that immediately, but it’s in the critical path for my project to re-think that setting, so probably sooner rather than later.
Image credit: NASA/JPL-Caltech
Just came across an interesting paper which seems to be exciting some comment: “Properties of Free Floating Planets Ejected through Planet-Planet Scattering.”
The abstract suggests that most planetary systems eject a few planets in the first billion years or so after their formation, with the ejected planets becoming “rogue” or “free-floating” planets in interstellar space.
The current Architect of Worlds models do allow for some ejection of planets in the formation process, especially in the case of a “Nice Event” that scrambles the orbits of core-accretion planets in the outer system. This paper seems to suggest that the process is a bit more common and aggressive than the current Architect models would suggest. I’m bookmarking this paper for close reading later – it’s a good candidate for being taken into account in a putative second edition of Architect.
I recently came across a neat website by Kevin Jardine: Galaxy Map.
It’s an odd site. It’s not clear how it’s all organized. It looks as if the site’s owner planned to write a book about mapping our galactic neighborhood, but the project got abandoned at some point. Nevertheless there’s a lot of interesting data and some gorgeous maps there, if you dig around a bit for them. In particular, Mr. Jardine has used the Gaia data tranches to do some really interesting mapping of relative star densities, the location of clusters and major nebulae, and the location of super-bright stars.
The most immediately useful page on the site appears to be at Galaxy Map Resources, but there’s also a collection of maps at Galaxy Map Posters that includes the one I included at the top of this post.
Really neat material there, if you’re at all interested in writing near-solar neighborhood interstellar fiction.
An interesting result in the current issue of Earth and Planetary Science Letters, suggesting that Earth may have had a significant ring system lasting up to 40 million years during the Ordovician period, about 466 million years ago:
https://www.sciencedirect.com/science/article/pii/S0012821X24004230
The mechanism is particularly interesting, and has implications for Architect of Worlds. At present, the design sequence simply will not produce rings around a terrestrial planet comparable to Earth. In this case, the hypothesis is that a largish asteroidal body had a near-miss encounter with Earth, within the planet’s Roche limit, and broke up to form rings. Which suggests that any terrestrial planet in a system that includes at least one planetoid belt might have a temporary ring system at any given time.
I’ll have to think about this some more, but there might be some additional guidelines forthcoming to cover this case. Not to mention that a ring system would cut back on insolation and have a profound effect on planetary climate . . .
For several weeks now, I’ve been using a sequence of tabletop simulation games to generate a big chunk of the Fourth Millennium alternate history. These have included:
In particular, the past two weeks have been devoted to running through a home-brewed scenario of Pax Romana, based on the outcomes of the previous games. I’ve been making occasional posts to Facebook detailing how the game has been going, with comments about what the alternate history looks like. For my blog readers and patrons, and to preserve that commentary for future reference, I’m going to compile all of those posts here.
So, without further ado:
Well, this evening I did manage to get Pax Romana set up, using my home-brewed alternate-historical scenario. This picks up right where my Successors and Sword of Rome runs left off, in 300 BCE.
You can see Carthage in the lower left, ready to build up its western empire. A few Romans in central Italy, set to finish their conquest of the peninsula. An alliance between the western chunk of Alexander’s empire and Magna Graecia. A few of Alexander’s satraps asserting their independence in Asia Minor. Way off in the East, we have Alexander’s son and heir partnering up with the elderly Ptolemy of Egypt to pursue a new generation’s ambitions.
Let the games begin!
Spent most of the day “teaching” an online course (i.e., monitoring student progress and grading papers), and building a slide deck for next week’s Enormous Course lesson.
I also plowed through a game-turn of Pax Romana. I’m now at the end of Game-Turn II (about 250 BCE), and there have been some interesting developments.
Given the enforced alliance at the beginning of the game between “Greece” and “The East” in my home-brewed scenario, once the two empires have divided up Asia Minor there’s really only one direction for “The East” (the main body of the Alexandrian empire) to go. That’s across North Africa to fulfill one of Alexander’s old ambitions, the conquest of Carthage.
The campaign was fortuitously timed, just as Carthage was struggling with a “slave revolt” event (entirely historical, as Carthage always had trouble with internal rebellions). I looked at the odds facing the Carthaginian army, and decided that their best bet was to fall back on the Numidian hinterland and the settlements in Spain, and let the Alexandrian army deal with the rebels. So the outnumbered Carthaginian army is more or less intact to fight another day. Still, between the Alexandrian invasion and an opportunistic campaign by the Romans in Corsica and Sardinia, Carthage has lost a lot of territory.
“Greece” (the European sector of Alexander’s empire) has been having a hard time expanding anywhere. They’ve knocked out a few barbarian tribes, but they also had to fend off a massive invasion of German barbarians from the back-end of nowhere, and the net result has been just about zero. Maybe in the next few turns they can do better – they certainly have the economic base for conquest, even if they also have a big frontier to defend.
The Roman Republic has been doing . . . not too badly, actually, mostly by carefully leaving the Alexandrians alone and snapping up territory opportunistically around the edges. They’ve had to fight some wars against Gaulish barbarians, but that gave them a chunk of southern Gaul and plenty of directions for further expansion. Once the two segments of Alexander’s empire become hostile to each other, there’s every likelihood the Romans can start playing both ends against the middle.
I really ought to be working on things for the office, but honestly I was pretty burned out this morning, so I spent the day on Pax Romana instead. The capstone scenario I need to write is still percolating in the back of my brain, so tomorrow I’ll sit down and knock out as much of it as I can.
In the Fourth Millennium universe, we’ve reached about 175 BCE, the halfway point in the simulation.
There have been some interesting developments. The entirety of Magna Graecia has changed hands, for one thing. The Greek cities in Italy are now subject to the Roman Republic, while the post-Minoan matriarchy that was ruling Sicily is now a vassal-state of the Ptolemies of Egypt.
In the far west, now that the Romans have unified Italy, they’ve drawn a new strategic objective: the conquest of Hispania. Spain has just been unified by the league of post-Carthaginian towns left behind after Carthage itself was conquered by the Ptolemies. Unfortunately the Phoenicians have maybe half the economic strength of the growing Roman state, their social stability is much worse, and their armies tend to be smaller and of lower quality than the Roman legions. I’m predicting an alternate-historical version of the Punic Wars, with much the same outcome. Ceterum censeo Carthaginem esse delendam.
Meanwhile, now that Alexander’s empire has fragmented, there’s an epic confrontation brewing in Asia Minor, between Alexander’s direct heirs and the Seleucids who are based out of the Macedonian homeland and Greece. Right now the two powers are about evenly matched, so I have to wonder if they won’t just fight each other to exhaustion. A really talented leader on one side or the other might make all the difference. Have to see how the next couple of turns go.
As I move toward finishing up with my Pax Romana run, the world is starting to look like its status in the proposed Fourth Millennium RPG. The current date is about 125 BCE, and I’ve got 75 years to go.
In the west, the Romans have dealt with the post-Carthaginian towns and a couple of barbarian invasions in Spain, and have secured the eastern and southern coasts of the peninsula. That’s about where they were about 75 years earlier in our history, after the Second Punic War. At the moment the Roman Republic is the second-most powerful of the major empires, and they’re well placed to finish the conquest of Hispania and move into first place.
There’s still a “Carthage” in the game, and it’s even managed to take back a little of its old territory from the Ptolemies, but I’m reading that as a resurgence of the kingdoms of Numidia and Mauretania. I can’t see those hanging on to their independence very long if any of the major empires find the time to look their way. At least they can act as a spoiler for a while longer.
The conflict between the pieces of Alexander’s empire has been grinding onward. The loose and often-fractured alliance between Alexander’s direct heirs and the Ptolemies of Egypt has been doing surprisingly well. The Seleucid kingdom in European Greece was hamstrung by a very badly timed civil war, and by the arrival of a “soldier of fortune” mercenary army working for Alexander’s descendants. (Pax Romana includes a “soldier of fortune” mechanic, which can disrupt things by bringing a rogue military force onto the board for a turn or so. Think Pyrrhus of Epirus, or some of the third-tier Diadochi.) As a result, the Seleucid position in Asia Minor is in full collapse, and Alexander’s heirs have just about consolidated everything up to the islands off the Ionian coast. This game allows for lots of reverses of fortune, though, so no guarantees what will happen before the end-of-game date.
I suspect I’ll be finished with this run later this week. After which I think I’m going to fire up Affinity and start a really big cartography project, the kind of thing that might end up in the eventual RPG book. Starting with a master map of the whole Mediterranean world, with maybe a few more-detailed local maps as well. I doubt any of that will be finished by the end of July, but maybe my patrons will have some pretty maps to look at in August.
Finished my Pax Romana run last night, and carefully documented the state of the world. That brings the Fourth Millennium timeline up to my planned date – about 60 BCE.
The post-Alexandrian empires have had about a century of actually getting along with each other and not going through round after round of civil wars. Which means they’ve both been able to urbanize and expand their territory. The Seleucids, in particular, have managed to do something interesting – wedged in between Rome and the Alexandrians, they’ve expanded northward into the Balkans, and the territory of the eastern Celts along the Danube River. They’ve got a whole network of military colonies in that whole region, acting as a matrix in which the Celts can be Hellenized, formed into a solid defensive line against the incursion of Germans from further north. If I can’t build that into an environment for lots of adventures, I need to turn in my badge.
Meanwhile, the Roman Republic is the biggest, most unified, and wealthiest of the major powers . . . but it’s not strong enough to fend off both wings of the post-Alexandrian empires at once. Italy is starting to seem like a morsel caught in the jaws of Hellenistic states to the north and south. In the last turn of the game, the Romans had to fend off attacks from both sides, and lost small but significant portions of territory in both directions. What’s worse, the Republic just suffered its first serious round of military reverses, with whole legions lost and its internal stability sliding – which suggests it may be in for this world’s equivalent of the bloody Social War.
In power politics, a tripod is the most unstable of structures, because the temptation is always there for two powers to gang up on the third. So in the present day of the Fourth Millennium, is the Roman Republic going to go down before the Hellenistic conquest? Or will the post-Alexandrians collapse into factional fighting (again) and give the Romans a chance to get the advantage? After all, it’s not as if the Hellenes of this era have ever managed to go very long without starting to imitate the moment-to-moment business of a bucket of crabs.
This is going to be a great setting for adventure stories and a tabletop RPG. Next step: to build some maps of the current situation, and maybe write the first gazetteer of the setting. That’s not going to be finished before the end of July, but I suspect I’ll have some neat material to show my patrons next month.
Purely for amusement’s sake, here are the GURPS Spaceships writeups for four spacecraft in the Human Destiny setting. I’ve been finding it useful to draw up these ships using the GURPS rules, because they’re a pretty clean (and appropriately generic) system for spaceship design. Naturally, I’ll be adapting these to more system-agnostic terms as I write them up for the Human Destiny sourcebook. You’ll notice I’m already converting certain measurements to the metric system . . .
Built on a 1,000-ton (SM+8) 60-meter streamlined hull, this large vehicle was a workhorse of the development of the outer Solar System.
dST/HP 70. HT 12. Hnd/SR -2/5. Move 0.5G/30 mps. Air Speed 2,800 kph. Air Hnd/SR -2/5. SM+8. Loaded mass 1,000 tons. dDR 10. Occupancy 4+60SV. Load 606.4 tons. Cost $28.9 million.
Built on a 1,000-ton (SM+8) 75-meter streamlined hull, this large spaceplane can be found all across the Hegemony. It can ferry passengers and cargo to and from the surface of inhabited worlds, make short journeys in interplanetary space, or serve as auxiliary craft for a starship.
dST/HP 70. HT 13. Hnd/SR -1/5. Move 1G/c. Air Speed 4,000 kph. Air Hnd/SR +3/6. SM+8. Loaded mass 1,000 tons. dDR 30. Occupancy 6+60SV. Load 606.6 tons. Cost $73.6 million.
Built on a 100,000-ton (SM+12) 200-meter unstreamlined hull, this ship has a deep and rich history in the development of the Sol system. One of these vehicles, named Enterprise, was the first (and for a long time the only) Hegemony spaceship ever placed under human control.
Under human command, Enterprise spent decades journeying tirelessly through interplanetary space. The ship was used to set up asteroid-mining bases, to place industrial colonies on the moons of Jupiter and Saturn, even to venture out to the Kuiper Belt and harvest comets for the terraforming of Mars. Along the way, the ship gave thousands of humans experience in deep-space operations using Hegemony technology. This cultural experience stood them in good stead when the Hegemony unexpectedly opened the way to the stars in the early 23rd Century.
dST/HP 300. HT 14. Hnd/SR -4/5. Move 0.01G/180 mps. SM+12. Loaded mass 100,000 tons. dDR 70. Occupancy 344ASV. Load 18,494.4 tons. Cost $16.34 billion.
This starship, built on a 30,000-ton (SM+11) 150-meter unstreamlined hull, is a mainstay of the Hegemony’s mission to explore and monitor interstellar space. Thousands of ships in this class are constantly on the move throughout the wilderness spaces supervised by the Khedai Hegemony. In particular, ships like this began to fan out from Sol soon after the Conquest.
Early in the 23rd Century, the Hegemony began to recruit human crew for these exploration missions, permitting them to contribute to surveys within ten parsecs or so of Sol. Later, Aminata Ndoye (one of the first humans to earn officer’s rank in the Interstellar Service) worked aboard several ships of this class. Indeed, she was the first human to command one of them, the Challenger, during its history-making expedition toward the stars of Orion.
dST/HP 200. HT 14. Hnd/SR -2/5. Move 2G/c. SM+11. Loaded mass 30,000 tons. dDR 150. Occupancy 184ASV. Load 5,508.4 tons. Cost $14.0 billion.
I’m currently in the process of a final editorial and layout pass on Architect of Worlds before the book gets released. For an idea of how that’s going, I’m up to page 62 out of 188, and as long as I can wrangle an hour or two in a given evening, that usually gets pushed another 10-12 pages forward.
I hadn’t planned on doing extensive rewrites of any of the existing text as part of this final pass – just polishing typos and stylistic inconsistencies, and preparing the layout for both e-book and print releases. However, I’ve recently come across some research that really asks for some revisions of the current model. (Thanks to patron Thanasias Kinias for putting me on this particular trail.)
The subject is what Architect calls Class 2 or “Dulcinea-type” worlds. These are super-Earths that have thick atmospheres dominated by primordial hydrogen and helium, and in the Architect model they almost invariably have lots of water as well. In astronomical circles, these are starting to be called hycean worlds (“hycean” coming from “HYdrogen” and “oCEAN”). It’s been one of my secret pleasures that the models used in Architect allowed for such worlds before they became a common hypothesis in real-world astronomy.
Some of my recent reading, though, tells me that Architect is probably dead wrong about some of the surface conditions of such worlds.
For one thing, astronomers modeling such worlds have suggested that they need more than just plenty of mass to hold onto that primordial hydrogen and helium. The issue isn’t simple Jeans or thermal escape (which Architect does model), but the fact that a world too close to its primary star will likely have that primordial envelope blasted away by its ultraviolet and X-ray output and stellar wind. Once the primordial atmosphere is gone, it’s not likely to be replaced by vulcanism and outgassing, so the eventual atmosphere will more closely resemble the nitrogen-carbon dioxide mix typical of a smaller world.
On the other hand, I’ve assumed all along that the primordial hydrogen and helium in the dense atmosphere of such a world wouldn’t generate any greenhouse effect. Molecular hydrogen and helium aren’t polar, so by themselves they don’t tend to be opaque to infrared light the way (e.g.) carbon dioxide or water vapor can be. Unfortunately, there is a way that a dense hydrogen atmosphere can generate a pretty significant greenhouse effect – I don’t entirely understand the physics of it yet, but in the papers I’ve been reading the effect is described as pretty pronounced.
Normally I wouldn’t be too worried about any of this, but both Architect and real-world astronomy suggest there there are a lot of super-Earths out there. Any plausibly realistic interstellar setting is going to have to contend with them. So I think I need to make some adjustments to the final release version of the text. I think the relevant steps in the design sequence are Twenty-Six, possibly Twenty-Eight, and Thirty.
One interesting thing about this change: not only should it model these hycean (Dulcinea-type) worlds more accurately, it may open the window to a wider variety of Earth-like planets. At the moment, Architect says that a world doesn’t have to be very much bigger than Earth before it starts retaining (at least) primordial helium. If I make the conditions for that a bit more restrictive, we may end up seeing more “just-a-little-bit-super-Earths” that have a fully Earthlike atmosphere. At least you’ll be able to land and walk around on them without sounding like Alvin and the Chipmunks.
So yeah, this is probably the last set of changes to the Architect design sequence before release. Which implies you’re all going to have to wait for said release to see the results, but at least that event is getting closer by the day.
Some links to useful references:
Innes, H. et al. (2023). “The runaway greenhouse effect on hycean worlds.” The Astrophysical Journal, 953:2.
Pierrehumbert, P. and E. Gaidos (2011). “Hydrogen greenhouse planets beyond the habitable zone.” The Astrophysical Letters, 734:L13.