Star Wars: The Scale of the Galaxy

   In the Star Wars universe galactic civilization is tens of thousands of years old – and is still using much the same technology as it was thousands of years ago. City-worlds have been city-worlds for thousands of years, millennia-old technologies are still in common use, and the Sith and Jedi continue to assail each other, as they have for eons. Individuals often surpass such limitations, but their advances often seem to die with them; such “advances” may actually be nothing but a manifestation of personal abilities.

   Evidently things are pretty steady-state and the practical limits of many technologies have been reached. Ergo, it’s worth taking a look at just what that state is, regardless of the details of when and where a particular Star Wars game is set.

   The Milky Way contains somewhere between 200 and 400 billion stars, depending on the number of low-mass stars (which is highly uncertain) and has a total mass of approximately three trillion solar masses. It seems to be fairly average as spiral galaxies go, and the “out of the galaxy” shots in the movies show what looks like a fairly normal galaxy.

   Going by the movies and novels, virtually every star has planets – and most of them seem to have inhabitants. Quite a few random large moons do too. Admittedly, much of the time those inhabitants seem to be relatively small resource-exploitation colonies, but that would give us at least ten inhabited “worlds” (including inhabited moons and those colossal space installations) per system.

   That would make roughly three trillion inhabited worlds. That’s 3 x 10 to the 12’th power. Roughly four hundred and fifty inhabited worlds for every human being alive today.

   That means that claiming that any product of even the slightest importance coming from a single world is about as absurd as claiming that one person, working one day a year in their basement, produces all the automobiles made on earth.

   That tells us that the odds of some random lead going back to a planet you’ve been to before – or have ever even heard of – are minuscule. That interstellar bounty hunters are pretty much a myth. That even if we assume that one average Jedi suffices to look after ten entire planets (a job that even Superman and his friends seem unable to fully accomplish, despite super-intelligence, time travel, and many other advantages unavailable to the Jedi), that would mean that there were three hundred billion active-duty Jedi. Opposing that, we have the stated numbers of the Clone Army; a mere two hundred thousand at first, and perhaps two million at their peak. As is very common in fictional “galactic armies”, the entire force included far fewer people than the sixteen million who served in the United States military alone during world war two. That really isn’t enough to assault a single planet, much less to harass the adult in-service Jedi, who would outnumber the clone troopers one hundred and fifty thousand to one. For a similar consideration of scale, if Darth Vader was hunting down Jedi, and killed one every ten minutes, twenty-four hours a day, three hundred and sixty-five days a year, he could expect to finish up in a mere five or six million years – except for the fact that there would be new kids born in the meantime. The Jedi might not even notice his efforts.

   Planets only last about ten billion years anyway, which mean we can expect about 300 to be destroyed per year – roughly one per day on the average. Ecospheres don’t last nearly that long: one can expect dozens of planetary extinction events per day. Give travel time, the Death Star wouldn’t make a noticeable contribution even if you ran it continuously at full capacity.

   This won’t work. So lets throw in some additional assumptions:

   1) 99% or more of the Star Wars galaxy is uninhabitable – afflicted with gamma-ray bursters, excessive levels of radioactivity, robotic death machines left over from ancient wars, dense nebula that produce too much meteoric activity for stable ecospheres, and various other destructive effects. There may be small pockets of inhabitable systems in the depths of such regions, but they usually pass unnoticed unless they develop civilizations and probe outwards.

   2) Many ecosystems – another 99% or so – host such dangerous toxins, force-using predators and force-based defenses, and similar obstacles – that they are effectively unusable. Such planets are deathtraps for sapient lifeforms. Why is that? It’s simply because lifeforms do not develop intelligence if they possess the raw physical or force-based power to dominate their ecosystems anyway. Ergo, the most dangerous animals are far more dangerous than the most powerful individual sapient beings. Sapient races are quite rare – rare enough that even many suitable planets, much less the 99% unsuitable ones, do not host an indigenous sapient species.

   3) There are hardly any resources that are worth exploiting at interstellar ranges; unless there’s an inhabited planet in the system; establishing asteroid colonies and such is hopelessly uneconomic. Those which are established usually collapse within twenty generations.

   4) The Arrhenius Spore Theory is accurate: almost all life in the Galaxy shares a common basic biochemistry and genetic structure. Many sapient “races” are in fact simply genetic variants of a relatively few older races, which have colonized, collapsed, and recolonized repeatedly over the history of the galaxy. Some are still even interfertile, at least with limited technical or force-based assistance.

   5) The galactic fringes or “outworlds” are too spread to be effectively incorporated into the mainstream of galactic civilization, and rarely even have regular contact with the galactic mainstream. We can dump another 90% of the possible worlds from consideration.

   That reduces things by a factor of a hundred thousand, taking us down to a “mere” 30,000,000 worlds. That’s still far too many – honestly, the Star Wars “galaxy” seems to contain a few thousand systems at most – but it’s a lot more manageable. We need a few more assumptions though to get things entirely under control.

   6) Many types of stars – Red Dwarves (Brown Dwarves were not included in the initial estimate on the number of stars anyway), those significantly hotter than the sun, Giants, and so on – virtually never have any worthwhile planets. Since Dwarves are small and difficult to see, they’re often not even cataloged. Their presence is one of the things that makes random jumps into hyperspace (“jump to lightspeed”) dangerous and forces most ships to stick to well-established routes. That takes another 90% or so off. We’re down to a mere three million planets. Darn it. I still want to get rid of some more planets. Move over Darth! I’ve eliminated 2,999,997,000,000 inhabited worlds already, and I’m not satisfied yet!

   7) Sapient life often makes a mess. Roughly 90% of the worlds that are otherwise suitable for sapient life do not support it. They may have been devastated by war or by various superweapons (apparently all too common in the Star Wars universe), over-exploited to the point where they’ll need a geologic age to recover, have been polluted past the point of viability as homes for civilizations, suffer from excessive climactic instabilities, or otherwise be just too unpleasant.

   That leaves us with a mere 300,000 worlds in the galactic mainstream that support significant populations (and gives me a 99.9999% kill ratio, which I suppose will have to suffice).

   Now, according to some of the sources – I’ll use Wookieepedia for quick reference – at it’s peak, the Galactic Empire consisted of more than a million planets and up to fifty million colonies, protectorates, governorships, and puppet states. Given that we have no idea how many essentially uninhabited planets the empire officially claimed, and that there could easily be several hundred such subunits (major asteroid colonies, Oort cloud colonies, gas giant mining colonies, etc, etc, etc) within one inhabited solar system, we’re probably looking for a smaller number still – but we’re getting down to within the right range.

   So: the Galactic Empire controlled – say – 80% of the populated worlds of the inner galaxy, or about 240,000 of them. Of course, it also laid claim to everything else in those solar systems – including small colonies on other planets and major moons, completely unusable planets (most of those other worlds would fall into the 99% near-lifeless, frozen balls of ice, or too dangerous to inhabit category), and small states on planets that (like many or most) lacked a unified government.

   What are those worlds like?

  • .1% (or about 240) are World-Cities, like Coruscant – with a population of around 3 Trillion people each.
  • About 5% (12,000 or so) are fully-industrialized, civilized, worlds, with an average population of about 20 billion each.
  • 80%, or close to 200,000, are low-population or primitive colonies, asteroid belt settlements, and similar locations, averaging around 100 million people per world. These usually don’t see a lot of galactic traffic.
  • The remaining 4.9% are a mixed bag, and include worlds with very harsh environments, marginal worlds, recently devastated planets, and similar places. They won’t be included in the basic estimate.

   Overall, that comes out to 980,000,000,000,000 – plus a small percentage for assorted lesser orbital colonies, that 4.9% of mixed-bag worlds, and assorted small moons. Call it a nice even Quadrillion (or 10 to the 15’th power) individual sentient beings. We can probably double that to account for the outworlds – which, while they are less developed, still outnumber the inner worlds by nine to one.

   That would indeed make the Yuuzhan Vong war – with casualties estimated (per Wookieepedia) at 365 Trillion – perhaps the most destructive war in history, accounting for the death of roughly 18% of the galactic population (presuming that the number does not include the Yuuzhan Vong casualties themselves and that the estimate is accurate). Of course, it’s still not comparable to the Black Death – often estimated at 30-60% of the European population – but that was a lot more localized.

   Now, for practical purposes – especially given the massive near-impassible zones so common in the galaxy – we can probably ignore a lot of backwater worlds, pockets of worlds that are hard to get to, and minor distant worlds. If you’re mostly concerned with a particular galactic sector, we can expect most of the action to take place in a relatively small cluster of easy-to-reach worlds – perhaps a mere .1%, or 240. 80% of those will be minor worlds – leaving 48 major worlds.

   Ah, now we know why things keep coming back to that relatively small list of planets, and how bounty hunters can operate, and so on: this may be a galactic setting in theory, but in practice it’s more like a bunch of cities – each at the center of a cluster of smaller towns – scattered across a small continent.

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One Response

  1. […] Scale of the Galaxy: Or why anyone can find anything despite it being a Galactic Civilization […]

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