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Old 12-01-2020, 05:04 AM   #1
scc
 
Join Date: Mar 2013
Default [Space] The Benefit Of Building A Single Big System

So while tinkering with one of my on-again, off-again project a couple of days ago is that designing a single, massive star system is the best option 8 times out of 10 for the aspiring designer. Unless you WANT to the the Star Wars thing and give your players an entire galaxy, you (and your players) are probably looking for some way to limit the scope of your universe, and designing a single star system with multiple stars (and multiple habitable planets) is a good way to do that.

But things go further, page 236 of GURPS Traveller: Interstellar Wars posits the idea of a multi-generational campaign, however this is limited by the fact that during the course of the Interstellar Wars a true paradigm changer never happens, my setup? Well the story presumably starts in the earliest days of spaceflight when the TL is barely 7, and possibly not even that, and things are very steampunk and ends, well, whenever you want it to, with the societies of the setting changing along the way, and the PCs are there to influence the story.

And if your players don't want to do the multi-generational thing, that's fine, they don't have to, but you can move around different parts of you history for different types of games very easily, and because you've already done a lot of the work, it's easier, and there's less to tell your players, because you last game was set 100 years earlier on the same world.
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Old 12-01-2020, 06:10 AM   #2
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Default Re: [Space] The Benefit Of Building A Single Big System

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Actually, he probably went one step further, and simply didn't worry about how many giant balls of hydrogen were involved, but only caring about the planets and enough space between for his characters to have their stories. This is pretty much the Star Wars attitude as well. Sure, that's notionally a whole galaxy, but when it takes a matter of hours (certainly canon by the last film) to visit not one but several of them in series, it might as well be one giant system (other than simple physical implausibility -- but we already said "Star Wars"). Travel time is narratively what counts, the propagation delay between cause and effect.

You can have restricted scope with planets around different stars by restricting the speed of the FTL drive. Make that realistic enough, and it's only marginally different from having just the Earth system as a setting. Turn the knob to include more stars and worlds; turn down the realistic physics knob to get more actually interesting planets on which to set stories, rather than endless repetitions of boring iceball, rockball, gasball. (Or tiny rock and tiny ice cube, if you want to do Belters or Oort-cloud expansion through planet-abandoning gradual STL expansion.)

I think you're exactly right in that the key problem for the game-world-builder isn't the physics technobabble, but starting with the idea of what stories they want to tell and what the scope of those needs to be. Then you make up the assumed technology to fit what your story needs.

You can do it the other way around, too -- pick some properties of the assumed technology, and see what stories that inspires, or just tell the story about the technology, 1950s hard SF style. The pitfall there is well known to RPGers, as pretty much zero game systems have the detail and resolution from which to actually mechanically extrapolate some inevitable, single yet mutually agreeable endpoint. That's more an intellectual exercise where the fun is in the building and perhaps debating ways that path might go. The stories of individual characters here are probably highlighting the turning points or "day in the life" stories that help the players get a feel for the changes and turns.
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Old 12-01-2020, 07:52 AM   #3
AlexanderHowl
 
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Default Re: [Space] The Benefit Of Building A Single Big System

While you could potentially have one big system, there are some reasons why the physics does not work beyond a certain point. First, there are issues of minimum separation between stars, as planetary orbits are not stable beyond a third of the separation between two stars. Second, there are only so many possible habitable planets/moons that a star can host.

Now, a compromise would be systems within a global cluster. While global clusters are thought to have low metal stars, they may paradoxically be surrounded by a lot of metal in the form of debris due to lots of their more energetic members having detonated billions of years ago (the stars themselves would show up as metal-poor because any debris that fell into them would have ended up in their cores billions of years ago). While the stars in the core are probably packed too tight for any planets, they would account for only half of the systems, meaning that half of the systems could potentially possess planets that formed from supernova debris.

For example, Omega Centauri possesses 10 million stars within a radius of 86 ly, meaning that they have an average separation of .8 ly. Even if only 50% of them have planetary systems and only 20% of those planetary have habitable planets, that is still one million stars orbited by habitable planets.
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Old 12-01-2020, 09:00 AM   #4
Flyndaran
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Default Re: [Space] The Benefit Of Building A Single Big System

I just don't see any way to have multiple star systems and playable travel times in a realistic setting. And once you invoke FTL at all, you might as well fudge a bit with other facets to keep the game going and fun whatever that means for the particular group.

Edit: Personally, the idea of a dozen or so habitable worlds in a single star system is more unpleasant to my mind than FTL.
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Old 12-01-2020, 09:09 AM   #5
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Default Re: [Space] The Benefit Of Building A Single Big System

Quote:
Originally Posted by Flyndaran View Post
Edit: Personally, the idea of a dozen or so habitable worlds in a single star system is more unpleasant to my mind than FTL.
This is my opinion as well. That a more complete system of physics should allow faster than light travel should allow faster than light travel does not stretch my suspension of disbelief unduly; that the well-understood principles of orbital mechanics should be modified sufficiently to fit dozens of planets in a star's habitable zone causes my internal implausibility alerts to start going off in ways that tend to interfere with my enjoyment of the work.
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Old 12-01-2020, 11:24 AM   #6
Fred Brackin
 
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Default Re: [Space] The Benefit Of Building A Single Big System

Quote:
Originally Posted by AlexanderHowl View Post
Even if only 50% of them have planetary systems and only 20% of those planetary have habitable planets, that is still one million stars orbited by habitable planets.
Habitable for creatures that float in the atmospheres of gas giants maybe. Even te clusters that show 2 generations of star formation have those being brief periods of star formation and being long ago.

So the stars that have survied in globular cluters are small and old and not at all likely to have rocky planets.

By contrast stars in open clusters are young and recently formed. Very likely too young. I read a blurb a year or two ago about a team that thought they had found the first known star that formed in the same cluster as our Sun and it was hundreds of ly away.
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Old 12-01-2020, 01:18 PM   #7
Stormcrow
 
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Default Re: [Space] The Benefit Of Building A Single Big System

Quote:
Originally Posted by AlexanderHowl View Post
While you could potentially have one big system, there are some reasons why the physics does not work beyond a certain point.
Quote:
Originally Posted by Flyndaran View Post
I just don't see any way to have multiple star systems and playable travel times in a realistic setting.
Quote:
Originally Posted by ravenfish View Post
that the well-understood principles of orbital mechanics should be modified sufficiently to fit dozens of planets in a star's habitable zone causes my internal implausibility alerts to start going off in ways that tend to interfere with my enjoyment of the work.
I don't see any sign of scc particularly wanting a realistic setting. As the Firefly example shows, if the narrative is more important than the physics, then there's no reason to demand realism.

That said, I think any scope can be used in that narrative mode, provided you set your technologies and distances correctly. Slower-than-light speeds for a single star system, slow faster-than-light speeds for a limited number of star systems in a certain range, or fast faster-than-light speeds for an entire galaxy. The slower you go, the more your ability to travel depends on your technology. The faster you go, the more your ability to travel depends on narrative convenience. These are the parameters a wise GM will take into account.
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Old 12-01-2020, 01:39 PM   #8
AlexanderHowl
 
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Default Re: [Space] The Benefit Of Building A Single Big System

The problem with any realistic travel between planets in the same star system is that they are either inconveniently slow or distressingly energetic. A SM+8 spaceship travel at 300 km/s possesses the equivalent energy of a 10 megaton nuclear weapon, and it would still take a couple of days for travel between the closest of worlds. A velocity of 3,000 km/s would be required to open up the entire system to a few weeks of travel, and that same SM+8 vehicle is now the equivalent of a 1 gigaton nuclear weapon.

Conversely, a setting where hyperdrives and/or inertialless boost drives existed could be much less dangerous. In such a setting, a hyperspace velocity of 100c, a hyperspace shadow of 40 AU of an Sol-mass object, and inertialless boost drives with a velocity of 30,000 km/s would allow spaceships to travel anywhere in a system in a few days and between close systems with a couple of weeks. While it breaks (or at least bends) the laws of physics as we know them, it actually results in a more acceptable setting, as civilians do not have access to technologies that can wreck small nations.
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Old 12-01-2020, 01:47 PM   #9
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Default Re: [Space] The Benefit Of Building A Single Big System

We have lots of theories about what makes rocks habitable, but it's easy to lose sight of the fact that we only have one well-explored solar system. Maybe it will turn out that gas-giant moons are more likely to be hospitable than rocky planets. Or that binary systems regularly produce a slew of terraformable rocks. Or... something. Our sample size sucks and we're making the best guesses we can.

Like others, I recommend you consider your narrative and make decisions from there.
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Old 12-01-2020, 06:26 PM   #10
scc
 
Join Date: Mar 2013
Default Re: [Space] The Benefit Of Building A Single Big System

Quote:
Originally Posted by Anaraxes View Post
You can have restricted scope with planets around different stars by restricting the speed of the FTL drive. Make that realistic enough, and it's only marginally different from having just the Earth system as a setting. Turn the knob to include more stars and worlds; turn down the realistic physics knob to get more actually interesting planets on which to set stories, rather than endless repetitions of boring iceball, rockball, gasball. (Or tiny rock and tiny ice cube, if you want to do Belters or Oort-cloud expansion through planet-abandoning gradual STL expansion.)
This doesn't really work, the infinite map problem still exists. Using Space Atlas and Space Atlas 2 as an example, if I place the map for Space Atlas 2 below the one from Space Atlas, Sheba (from Space Atlas) is closer to Fasgrin (from Space Atlas 2) then to any (other) system from Space Atlas.

Quote:
Originally Posted by Anaraxes View Post
You can do it the other way around, too -- pick some properties of the assumed technology, and see what stories that inspires, or just tell the story about the technology, 1950s hard SF style. The pitfall there is well known to RPGers, as pretty much zero game systems have the detail and resolution from which to actually mechanically extrapolate some inevitable, single yet mutually agreeable endpoint. That's more an intellectual exercise where the fun is in the building and perhaps debating ways that path might go. The stories of individual characters here are probably highlighting the turning points or "day in the life" stories that help the players get a feel for the changes and turns.
The interesting thing with what I'm doing here is that it's a good setup for multiple different campaigns that aren't connected apart from taking part in the same star system

Quote:
Originally Posted by AlexanderHowl View Post
While you could potentially have one big system, there are some reasons why the physics does not work beyond a certain point. First, there are issues of minimum separation between stars, as planetary orbits are not stable beyond a third of the separation between two stars. Second, there are only so many possible habitable planets/moons that a star can host.
The Liquid Water Zone extends out to about 3 AU max, at least for any star that's likely to stick around long enough for life to evolve, so not letting the stars get closer then 9 AU works.

Quote:
Originally Posted by AlexanderHowl View Post
Now, a compromise would be systems within a global cluster. While global clusters are thought to have low metal stars, they may paradoxically be surrounded by a lot of metal in the form of debris due to lots of their more energetic members having detonated billions of years ago (the stars themselves would show up as metal-poor because any debris that fell into them would have ended up in their cores billions of years ago). While the stars in the core are probably packed too tight for any planets, they would account for only half of the systems, meaning that half of the systems could potentially possess planets that formed from supernova debris.

For example, Omega Centauri possesses 10 million stars within a radius of 86 ly, meaning that they have an average separation of .8 ly. Even if only 50% of them have planetary systems and only 20% of those planetary have habitable planets, that is still one million stars orbited by habitable planets.
Thinks about the scale of what you're suggesting here for a moment. Also stop to think about how unstable such a situation would be, most of those stars likely won't have planets, due to a passing encounter with another star at the wrong time.

Quote:
Originally Posted by Flyndaran View Post
I just don't see any way to have multiple star systems and playable travel times in a realistic setting. And once you invoke FTL at all, you might as well fudge a bit with other facets to keep the game going and fun whatever that means for the particular group.

Edit: Personally, the idea of a dozen or so habitable worlds in a single star system is more unpleasant to my mind than FTL.
Not multiple star systems, a single system with multiple stars. And the abundance of habitability can be explained away with random chance panspermia, that is life evolved on one of these planets (and moons) and was then seeded to the others via asteroid impacts.
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