Population Density: SW vs ST

[Baffalo]

This was a question I asked myself recently: Obviously the Wars universe has a much larger population and number of planets. However, does that mean that the Wars universe has a higher population density per lightyear? Or is it actually more sparsely populated due to the range of hyperdrives?

I decided to place this question in SW vs ST due to its relevance in many arguments that Wars obviously has a higher population, but I would like to set a guideline for exactly how much higher the population is in relation to the Trek universe.

What I will offer is that the Federation is listed as having 1000 stars spread out over 8000 lightyears. Considering there are 150 members, this leaves 850 stars that are officially colonies, protectorates, and other various stars that do not meet the requirements for full status. So how would Wars stack up? I ask because I'm not that up to date on how Wars has listed their 'official' representation of stars within their borders.

[Jub]

Based on the worlds we see and the population density of DS9 I'm going to have to say Star Wars has a high population density per light year. Worlds like Coruscant and Nar Shaddaa have massive populations and they would bring the numbers up. Where as most of what we have evidence for in Trek suggests sparsely populated colonies and they have nothing to match the city worlds of Wars.

[Lord Revan]

Based on the worlds we see and the population density of DS9 I'm going to have to say Star Wars has a high population density per light year. Worlds like Coruscant and Nar Shaddaa have massive populations and they would bring the numbers up. Where as most of what we have evidence for in Trek suggests sparsely populated colonies and they have nothing to match the city worlds of Wars.

on the other hand City worlds like Corusant, Nar Shaddaa or Taris (pre-bombing) are somewhat atypical as far as Star Wars worlds are conserned and the Galatic Republic/Empire in considerbly larger then the UFP (btw has there ever any area numbers for the UFP?).

[Baffalo]

on the other hand City worlds like Corusant, Nar Shaddaa or Taris (pre-bombing) are somewhat atypical as far as Star Wars worlds are conserned and the Galatic Republic/Empire in considerbly larger then the UFP (btw has there ever any area numbers for the UFP?).

From what I saw on Memory Alpha, the Federation is approximately 8000 lightyears across. If you assume the territory expanded in a roughly spherical manner before becoming cylindrical later due to the shape of the galaxy, then you're looking at an area of 50 million square lightyears. That doesn't take into account the density of stars along the arms of the galaxy, the relatively sparse grouping between the arms, etc, but it's a decent approximation.

[Jub]

Based on the worlds we see and the population density of DS9 I'm going to have to say Star Wars has a high population density per light year. Worlds like Coruscant and Nar Shaddaa have massive populations and they would bring the numbers up. Where as most of what we have evidence for in Trek suggests sparsely populated colonies and they have nothing to match the city worlds of Wars.

on the other hand City worlds like Corusant, Nar Shaddaa or Taris (pre-bombing) are somewhat atypical as far as Star Wars worlds are conserned and the Galatic Republic/Empire in considerbly larger then the UFP (btw has there ever any area numbers for the UFP?).

Even if they aren't typical they still help to raise the average population density. There is also the fact that just because the Star Wars universe has a faster form of FTL that doesn't mean they wouldn't expand to nearby areas before looking further away.

[Batman]

The 8000 ly comment comes from First Contact and is never qualified as to wether that is length, width, diameter or whatnot. To those astronomically inclined I propose the question how many stars are there in an 8000ly sphere centered on Earth to begin with?
This is an honest question, I have no fucking clue.

[Mr Bean]

Not to mention you must count in species density, per SW EU there are over one thousand known sapient species that have achieved spaceflight and hyper drive technology. However many races are little seen outside their home worlds because for biological, social or historical reasons they don't get out much. Yet we have things like Devorians, Twilicks (However you spell them alongside Humans as actively expansionist as a species. Then you have species like Hutts who can be found all over the place along with other races that they enjoy employing.

If you want to set a low ballpark lets assume every intelligent race has one billion members including a hypothetical never mentioned human homeworld. So that gives us one trillion sapient beings there alone, add in known large city worlds of which we have roughly four I can count of the top of my head (Correllia, Kuat, Courscant, Nar Shaddar(Which is a moon) which have multi-trillion populations and we can easily set a low ball figure in the hundreds of trillions quickly. A high end figure Quintillion sized figure with Septillion at the high end.

[Eternal_Freedom]

on the other hand City worlds like Corusant, Nar Shaddaa or Taris (pre-bombing) are somewhat atypical as far as Star Wars worlds are conserned and the Galatic Republic/Empire in considerbly larger then the UFP (btw has there ever any area numbers for the UFP?).

From what I saw on Memory Alpha, the Federation is approximately 8000 lightyears across. If you assume the territory expanded in a roughly spherical manner before becoming cylindrical later due to the shape of the galaxy, then you're looking at an area of 50 million square lightyears. That doesn't take into account the density of stars along the arms of the galaxy, the relatively sparse grouping between the arms, etc, but it's a decent approximation.

Mate, you've got area and volume mixed up there.

As for how many stars are within 8,000 light years of Earth (or Sol, to be more precise). The best guestimate for stellar density in this part of the Milky Way I've been taught is about 0.12 stars per cubic parsec. An 8,000 light year/2454 parsec sphere is 6.19x10^10 cubic parsecs (4/3 x pi x 2454^3), so there should be about 7.5 billion stars within that distance from Sol.

Now, the big assumption in that is the stellar density, which is a figure based on stars within 150 light years (the Gliese catalogue mostly) and the density may well be different further out. Even within 150 light years there should be 14,600 stars and most of those are unknowns because they'll be yellow or red dwarves that are hard to detect.

So, within the maximum posible size of the UFP based on Picard's figure, there are about seven and a half billion stars. That's a shitload.

[Lord Revan]

For population desity the question isn't really the amount of stars total but habitable systems and the population on those and we know that neither ST or SW puts colonies on every stellar body they can find.

[Baffalo]

As for how many stars are within 8,000 light years of Earth (or Sol, to be more precise). The best guestimate for stellar density in this part of the Milky Way I've been taught is about 0.12 stars per cubic parsec. An 8,000 light year/2454 parsec sphere is 6.19x10^10 cubic parsecs (4/3 x pi x 2454^3), so there should be about 7.5 billion stars within that distance from Sol.

Now, the big assumption in that is the stellar density, which is a figure based on stars within 150 light years (the Gliese catalogue mostly) and the density may well be different further out. Even within 150 light years there should be 14,600 stars and most of those are unknowns because they'll be yellow or red dwarves that are hard to detect.

So, within the maximum posible size of the UFP based on Picard's figure, there are about seven and a half billion stars. That's a shitload.

That's the absolute upper number, but it's also inaccurate because the galaxy is not a sphere centered on Sol. It's a cylinder, which means there's a maximum height of approximately 1000ly. If you look at the border of the Federation and Romulan Star Empire, it appears to be a perfect line straight up and down when viewed from above, meaning that territorial borders are perfect lines. Also, there are star charts showing the Federation as being more of a ring moving along the galactic arm rather than moving in a sphere away from Earth.



Now, let's assume that Picard meant the distance from one end to the other, long ways. There are 13 boxes, assumed to be sectors, with 7 boxes being the maximum width, the furthest arm stretching to the next arm of the galaxy. However, we notice there are no clear references to any stars, so we're going to run with the assumption that Earth is on the leading edge facing the galactic center, and thus the border with the Klingon Empire is to the right (due to the stated position of Qo'nos being approximately 90ly away from Earth).

So, the position of Sol is not in the center but more off kilter, towards one end of the territory. That means that the population density is going to be much greater towards that end due to the proximity of Sol, Vulcan, Andoria, et al, with a few new planets scattered about and mostly colonies stretching out away from Sol.

So if we look at the map, and assume an average width of 4.5, 8000ly x 4.5 blocks wide / 13 blocks long = ~2770ly wide. So, with that number, we're going to figure out the volume of the Federation.

Because we're assuming the Federation is a ring, we're going to say that because Sol is 26,000ly from the center of the Milky Way. The circumference then of a ring all the way around the galaxy is 2 x pi x r = 163360ly. Because the Federation is only 8,000ly, that means the circumference of the Federation is only 4.897% of the total circumference of the galaxy. Now, with our supposed width of the ring, we'll divide by two and then use that to compute the area of the Federation, subtracting the inner ring (a1) from the outer ring (a2). So, a2 = (26x103ly + 1385ly)2 x pi = 2.356x109 ly2. a1 = (26x103ly - 1385ly)2 x pi = 1.9035x109 ly2. atotal = (a2 - a1) x 0.04897 = 22.1589x106 ly2.

Now, we're going to assume an approximate height of the galaxy as 1000 lightyears, which we simply multiply to our total for a grand volume of 22.1589x109ly3.

[Batman]

For population desity the question isn't really the amount of stars total but habitable systems and the population on those and we know that neither ST or SW puts colonies on every stellar body they can find.

Number of stars is the question I asked, though (thanks, by the way). And while that number is a hell of lot larger than I expected it still serves as an upper limit-the Federation can't colonize star systems that don't exist.
As E_F said most of those stars are dwarf stars and thus unlikely to have habitable planets/planets worth terraforming.
Not that I was particularly clear about that, but I meand diameter, not radius (I don't know about the 24th century but I doubt all that many people today would call the content of a 16000ly diameter sphere 'spread across 8000ly').

[Batman]

Past the edit window.

Now, we're going to assume an approximate height of the galaxy as 1000 lightyears, which we simply multiply to our total for a grand volume of 22.1589x10E9ly^3.

So, assuming E_F's star density is correct, that would still give us what, about 77 million stars in that volume?

[Eternal_Freedom]

Past the edit window.

Now, we're going to assume an approximate height of the galaxy as 1000 lightyears, which we simply multiply to our total for a grand volume of 22.1589x10E9ly^3.

So, assuming E_F's star density is correct, that would still give us what, about 77 million stars in that volume?

That volume figure comes out as 6.3958x10^8 cubic parsecs, so yes, 76.7 million stars. However, as I said, that's assuming the stellar density is the same. Since we're in an open cluster, there is every reason to think the density will fall off past a couple of hundred light years of Sol. I would imagine, based on Baffalo's number, that about 50 million stars would be more realistic.

You are right that I used 8,000 ly as a radius not a diamater. Running my numbers again for a 4,000 ly sphere with the same stellar density gives me a number of 928 million stars "in range." However, as Baffalo said, the MW disc is only 1 kly thick.

So, assuming a cylinder 1,000 ly deep and 4,000 light years radius, we get 567 million stars. Still a lot more than Baffalo's number, but unless I can find a better figure for the stellar density I feel confident in sayign that's a theoretical max limit.

Once again though, the vast majority of those woudl be boring, unremarkable, useless stars. Heck, ST even shows this. With 77 million stars in the UFP and only 150 members and a thousand or so colonies, habitable worlds are really rare. One star out of 67,000 should have a habitable world.

EDIT: Oops, i totally forgot, Sol is in the Orion-Cygnus Arm of the MW, a smaller "spur" that's seperated fromt he other arms by about five thousand light years of empty space. The Orion Spur is 3,500 ly wide and 10,000 ly long, which means (if my density number is right) there's about 121 million stars in the arm. It is therefore not hard to see why the UFP is the big kid on the block. If they hold 77 million of those stars in their border, then damn, they're doing well.

[Eternal_Freedom]

Ghetto edit: Damnit, further searching my notes has foudn that my 0.12 stars per cubic parsec was based on stars within just 5 parsecs from Sol. For objects within 15 parsecs it drops to 0.014 stars per cubi parsec. So take all my numbers and knock a zero off the end. Sorry everyone! Which gives us 56 million stars in my theoretical upper limit of the UFP, and 12 million stars in the Orion spur, and Baffalo's figure of 7.7 million stars in the UFP.

EDIT: Damn this isnt going well. The 0.12 number for within 5 parsecs includes stars of any absolute magnitude, whereas the 0.014 only includes stars of absolute magnitude 8.5 or higher. Since the Sun has an absolute magnitude of 4.83 this basically means they are excluding things like white and brown dwarves, neutron stars, shit like that.

[Batman]

7.7 million should still give the Feds plenty of opportunity to park their rather timid (at least per TNG) number of members and colonies, especially if that number does exclude stars unlikely to have habitable planets (though of course with Trek, you never know, for all I know some superrace nine gazillion years ago made a pet project of showing that yes, you absolutely positively can have a double dozen habitable planets around a neutron star if you tweak the star system right and did it all over the galaxy just to boast).

[Eternal_Freedom]

7.7 million should still give the Feds plenty of opportunity to park their rather timid (at least per TNG) number of members and colonies, especially if that number does exclude stars unlikely to have habitable planets (though of course with Trek, you never know, for all I know some superrace nine gazillion years ago made a pet project of showing that yes, you absolutely positively can have a double dozen habitable planets around a neutron star if you tweak the star system right and did it all over the galaxy just to boast).

I could buy a bunch of habitable worlds around a supergiant, they'd have to be a fair way out from the star but it would be doable. A neutron star, less so. for one, it doesn't emit any visible light, so planets would be cold and dark. Second, lots of tidal forces at a distance were tidal forces are a big worry. Third, I cannot be certain but I suspect that being in close (astronomically speaking) to a pulsar (rotating neutron star) woudl not be good for you.

[Baffalo]

There is a number being kicked around on Wikipedia that states the current average for most star systems appears to be 1.6 planets/star. Given that this number is growing, and most habitable planets are multi-planet stars, I'd wager the following:

• Most systems capable of hosting life are multi-star systems.
  They contain at least one jupiter-sized gas giant to keep the system 'clean' of debris that can bombard life.
  The systems must be fairly stable (in regards to orbits and whatnot)

Given that these conditions are extreme given the information we know about, even with 7.7 billion stars out there, I'd bet there are less than a million stars out there capable of meeting the requirements. Maybe less than 100,000 given that there wouldn't be much reason to expand so dramatically if stars were so plentiful. If a star is 10ly away capable of hosting a class M planet, and another is 15ly, why would you go further? Unless the Federation is specifically targeting worlds requiring almost no terraforming to inhabit and only later going back and terraforming worlds on the edge of this range.

The reason I suggest this is given in Star Trek II, and the creation of the Genesis Device. If planets were habitable enough that they were plentiful, grants for terraforming projects or research on such projects would be hard to come by. This explains why they were targeting barren worlds: the Federation doesn't have access to that many worlds to colonize. You can also find evidence in TOS: Errand of Mercy. Organia is the only world along the entire Klingon/Federation neutral zone to be class M. All those systems and only one can hold life? That's very sparse.

[ryacko]

They contain at least one jupiter-sized gas giant to keep the system 'clean' of debris that can bombard life.

Just curious, what's the difference between a gas giant to clean debris, and the the existence of a red dwarf to clean debris? Other then the fact that the red dwarf is 75 times the mass of Jupiter.

[Batman]

I suspect that something 75 times the mass of Jupiter in the position of Jupiter is going to have all kinds of interesting side effects on that solar system's makeup. And that's ignoring that even a red dwarf emits a not inconsiderable amount of radiation. Gas giants cleaning up the debris is a function of them being out there amongst the rest of the planets (where that debris typically accumulates) as much as their mass, while stars tend to be at the centre of the system even if they're moderately useless.
Things almost inevitably get more complicated for multiple-star systems, but the 'Jupiter as the system's broom' idea is almost inevitably based on this here solar system and by extension single-star configurations.