Traveller in 3D

[BetterThanLife]

OK I knew my numbers were off. Thanks to Nyath the nearly wise on the NBOS maillist.

Volume of a sphere is 4/3*Pi*r^3 So a Sphere with a Diameter of 156 parsecs has a volume of 1,987,799 cubic parsecs.

If we were to have 1 system per 2 parsecs then the Stellar density would be .239 systems per cubic parsec. (Nyath's number)

So in this case we have 475084 systems in our volume.

If we crank the average distance to 2.4 parsecs. That makes the system density drop to .138 and lowers our number of systems in the same sphere to 274625.

If we change the jump formula to (Jn+4)*.5, then Travel time across the Imperium of one year at Jump-3 increases the diameter to 182 parsecs, or a volume of 3156551 cubic parsecs. However if we at the same time increase the distance between systems to 3 parsecs (Still a Jump-2 apart.) Density drops to .071 systems per cubic parsec. Changing the number of systems in the sphere to 223280.

No real change. However if we allow the Imperium to shrink so that a message crossing the Imperium goes down to 10 months, then we keep the 156 parsec diameter and we are down to 141,134 systems.

Going the other way. (At 2.4 parsec seperation, using Thrashes formula for Jump). Running 33,000 systems so we can carve away chunks for the borders of the Imperium and come up with a different shape. the sphere is approximately 77 parsec diameter or about 6 months across.

Going with my jump formula then 33,000 systems at 3 parsec seperation for systems is a sphere with a diameter of 96 parsecs. message traffic adds just under 2 weeks. (Big deal.)

Going to an inverse exponential formula for jumps makes jump 5 and 6 virtually useless.

 

[BetterThanLife]

Thrash if we are required to jump to 10+ uninhabited systems in between inhabited systems then there are no interstellar economics. So going to only one in 22 are inhabited can't work. Everything is isolated.

I think cutting the size of the Imperium to a 6 month message travel time would probably be my best choice. It allows for more centralized government, but if the local Nobles have a habit of blocking that type of Imperial involvement then it won't have as much of an effect.

 

[BetterThanLife]

Originally posted by thrash:
</font><blockquote>quote:</font><hr />Originally posted by BetterThanLife:
If we were to have 1 system per 2 parsecs then the Stellar density would be .239 systems per cubic parsec. (Nyath's number)

Winch is a good guy, but he's off: that's the inverse of the volume of a sphere of radius 1 pc; it doesn't account for all the empty space in between the spheres. The density should be 0.177 systems per cubic parsec.

What I'm not sure about is why 2 pc is the magic number? </font>[/QUOTE]It is the LBB3 number for 2D system density. It is also the only number that gets close to the over 11,000 worlds based on the geography of the Imperium.

If we use your jump numbers then 2.4 becomes the magic number. For normal space.

 

[BetterThanLife]

Originally posted by thrash:
</font><blockquote>quote:</font><hr />Originally posted by BetterThanLife:
If we were to have 1 system per 2 parsecs then the Stellar density would be .239 systems per cubic parsec. (Nyath's number)

Winch is a good guy, but he's off: that's the inverse of the volume of a sphere of radius 1 pc; it doesn't account for all the empty space in between the spheres. The density should be 0.177 systems per cubic parsec.

What I'm not sure about is why 2 pc is the magic number? </font>[/QUOTE]OK, so what formula gets us to .177?

 

[aramis]

Here's why I used the 3.3 CuPc figure: it directly compare to hexes, in that it's a cube 1J1 on a side under by proposal. (Chris' is a hare larger, so I used his).

SO we can directly compare hexes to volume chunks, and ignore (for the moment) stellar densities.

Once we have a volume in J1-units, we can figure the volume, and then the requisite density, and then by extracting the cube root, the average separation in terms of J1. If the cube root of the inverse of the density is more than the distance for J2, ALL the trade systems are affected by increased distance and thus decreased profits.

Also note that the OTU has many J-1 Mains. The real stellar density won't support the kind of mains that the OTU has, unless we far more steeply curve than any of the suggestions yet.

 

[BetterThanLife]

Originally posted by thrash:
</font><blockquote>quote:</font><hr /> </font><blockquote>quote:</font><hr />Originally posted by thrash:
What I'm not sure about is why 2 pc is the magic number?

It is the LBB3 number for 2D system density. </font>[/QUOTE]Same problem, this time confusing area density with distance. Standard density is 1 system per 2 hexes; scattered is 1/3 (and actually a better match for the Spinward Marches and the Solomani Rim). At standard density, systems are 1.4 (square root of 2) hex-widths apart; at scattered, 1.7 hex-widths (sqrt 3). Based on the Known Stars List, this translates to an average real-space separation of 1.7 pc at standard density, and 2.1 pc at scattered.

Overall, this last isn't too bad a match for the real world, where the average separation is ~2.5 pc.

It is also the only number that gets close to the over 11,000 worlds based on the geography of the Imperium.

Don't see how you conclude this, when that's what you're trying to determine, isn't it?

</font>[/QUOTE]Actually The 11,000 worlds in the Imperium is Canon. The only to get close to that number, based on the 2D Map of the Imperium in the same source is to use the LBB 3 formula of one star every other hex on average. Which yields that, on average stars are 2 parsecs apart. Yes in the Spinward Marches they are farther apart. The same with Ley. However since the rules state 1-3 on a D6 +/-1 There also must be regions where the density is higher than 1 per 2 hexes. (Actually in those regions it is 2 stars per 3 hexes.) So the average overall according to the LBB3 rules is an average 2 parsec seperation between stars on the 2D map. The Shape of the 3D Imperium is what we are trying, or at least what I am trying to determine. But it is a shape based on information from the 2D Imperium.

As for closely packed spheres and determining distance, I read that, and remembered some of that class I took over 20 years ago. Though the math still eludes me. I guess I better get back to reading.

Though at this scale stars aren't spheres they are points. I guess though you can still only fit so many so the sphere would still apply. (Remind me to go back to school when I have time and can afford it.

)

If your numbers are more accurate then that greatly decreases the number of systems in the same radius. Let me get back to the math.

 

[aramis]

For reasons of packing math, as in, I don't want the headache of doing that, I use cubes in figuring.

It is a gross approximation, but it works. (note, for the tables, I did use sphere for the area covered by Jx, but not for the volume for average "cell" size. I also used a spreadsheet.)

 

[BetterThanLife]

Originally posted by thrash:
</font><blockquote>quote:</font><hr />Originally posted by BetterThanLife:

use the LBB 3 formula of one star every other hex on average. Which yields that, on average stars are 2 parsecs apart.

No, it doesn't. This is math, so I can say unequivocally: you are wrong. Go back and look at my previous post, and think about what I just said. It's important because it's messing up your subsequent calculations.

</font>[/QUOTE]Actually there are 1280 hexes in a 2D sector. Each hex has a 50-50 chance of having a system in it. (LBB3) Therefore there should be an average of 640 systems per sector. Each hex has an area of .866 square parsecs. Therefore a 2D sector has an area of 1108.513 parsecs and a density of .577 stars per square parsec on average. Or one star per 1,733 square parsecs. Since we are dealing with every other hex though our average seperation is should be 2 parsecs. Or is that math off someplace? With that number in 2D everything works based on the information provided in the CT books.

Obviously if these numbers are off then the conversion to 3D is starting with bad assumptions and would never work.

 

[aramis]

BTL: Several of the sectors are 1/3 density. A few are 1/36 (Reft).

The number of systems in reach from a given world and the distance from core to edge are the most important; anything else won't feel right, and will have drastic effects on what should happen in terms of the polity.

Chris' linear (but offset) approach produces a different ratio between J1 and J4 than does the classic 2d; mine does more drastically. Mine does, however, put about the right number of systems to preserve that as well. But it makes a huge difference for J2 traders, both in terms of how long it will take them to make the core (12 months instead of 30), What it doesn't do is provide far more target "chunks" (hexes or cubes) to which one can jump; therefore it does the least damage to all the trade systems.

 

[BetterThanLife]

Originally posted by Aramis:
BTL: Several of the sectors are 1/3 density. A few are 1/36 (Reft).

Yes, however since the average is 50-50 then there should also be sectors that are 2/3 density. (The Rift areas, in all honesty, in my eyeball number of sectors in the Imperium, I didn't count them.) Note that would be 2 out of 3 hexes and not an actual 2 per 3 parsecs, which Chris was quite right isn't mathematically a density.)

The number of systems in reach from a given world and the distance from core to edge are the most important; anything else won't feel right, and will have drastic effects on what should happen in terms of the polity.

Agreed though a reasonable ceiling on the number of Systems within that radius is also important or it will also destory the setting.

 

[aramis]

Funny, at standard density, I got a main running a winding 35 parsecs long, rolling dice. ANother of over 20 parsecs long, same 2.5x2.5 sector map. 3 of 10pc or so. (I was bored, had hexpaper, and dice, and time; wife was in ER for appendix removal. Didn't roll the worlds; just system locations.) Note that the map has a void in it, 6 parsecs in diameter, with a single world just off center... Dice (and statistics) can be way funky.

Odds or no, they are present in canon, and a real force to be reckoned with: how to represent such.

 

[BetterThanLife]

Actually, if we are dealing with simple shapes the closest approximation to the 2D Imperium is a Triangle. In fact a Right Triangle isn't a bad approximation.

I have no problem with the concept that there are uninhabited systems out there. In fact when Astrosysthesis generates the area, I expect quite a few uninhabited systems.

However to have all your systems as isolated as you propose, one system in 15 actually being habitated, that provides another problem.

The Jump-2 ship, under your formula, and under canon, can usually have several choices to get to another system. (In fact most systems in a 2D sector are accessable by a Jump-2 ship.) Normal cycle is one week in Jump, one week in system. If we cut it down to only one system in 15 are a useful destination, and we jump to less than useful systems in between destinations, and we cut the time in system, for the non-inhabited systems, down to 2 days for maintenance and wilderness refueling operations. (Because of the 100D limit, the size of gas giants and actual time refueling and refining fuel a typical 1G merchant is going to have to take closer to 3-4 days in system.) That means a trip from one port to another is going to take, typically, 15 jumps or 135 days, which is just over 19 weeks. So you go two systems and you are then in annual maintenance. (Because you can't make your next port in time.) How do you price the ticket for the trip? High Passage, Mid Passage, Low Passage and Freight. What do you do if your Spec Trade roll gets blown and you don't make much profit on that trip? How do you make your mortgage payments, with or without spec trade? Is every inhabited world at least a Class B Starport so you can perform annual maintenance?

On the higher traffic routes why isn't some Mega Corp putting in stations at the uninhabited systems and therefore inhabiting them? I mean canon lets a small population run a high tech class A starport, shipyard and fueling station. It seems to me there would be a bunch of those, and at many of those a service industry would grow up, from there a decent population, especially if there were discovered another reason to be there besides simply trade or being a way station. Suddenly your uninhabited systems are now inhabited.

With such travel times why is there interstellar trade at all? Much less a reasonable volume of trade. If there isn't a reasonable volume of trade how do you get a starship mortgage? (Who would finance it?) With all the wilderness refueling between stops and the ever present chance of a misjump, interstellar trade just got a whole lot more dangerous, without the fact that the Imperium can't even patrol the populated systems, so Piracy is a very real threat on every trip. Your interstellar trade will be virtually limited to large merchant vessels, that travel in convoy, typically with Naval escort and tanker support. Or will be virtually non-existant.

While it may seem more realistic to you to have the systems scattered more, and I am not saying it isn't, the playability of the system would require a total rewrite of the economics to the point where it isn't recognizable as Traveller.

As for mains, you have to have either mains or large clusters or J-1 ships are absolutely useless, instead of being the most economical ships to operate. A J-1 ship has the lowest overhead and the largest cargo capacity, for its size. If you are in the right cluster or making your run between the right 2-3 planets, then you don't have to worry about how many systems the ship can reach for either profitable freight/passenger carriage or Spec trade and a J-1 ship can actually turn a profit doing either, in 2D Traveller. In your model a Jump-1 ship will have to sacrifice 10% of its cargo capacity to carry additional fuel and make the same runs that a J-2 ship makes, but taking twice as long. So you get to go from one system to one other per year. You'll die of old age long before you do any real traveling.

A Scout Ship doing a Survey of the inhabited worlds within a sector would in 2D Traveller takes at least 17 years. (Yes I started Adventure 0 and did the math way back then.) In your universe it will take 15 ships 17 years or one ship 255 years!

With systems scattered so much you would be very hardpressed to run any kind of military campaign. Even if you figure that a Jump-4 ship is going to take less than half the time a Jump-2 ship takes to go from one inhabited system to the next, You are still looking at between 5 and 7 jumps just to get to the next system. So how the Imperium got so big, how the Interstellar wars got fought or the Solomani Rim war, none of it works.

When you broke the laws of supply and demand, did you expect there not to be any consequences? (Sorry couldn't resist.)

 

[aramis]

NotChris:

average separation = density^(1/dims)
where
- dims= is number of dimensions.
- distance is in linear units
- density is in dimensional units of linear units ^ dims (2d is sqaure units, or hexes or triangles; 3-d is cubic units, which may not be cubic in shape) per item. (Essentially, the inverse of the fraction of space measured to contain systems, in quatized units matching the linear units.)

For most of our purpose here, we can quantize space into units J1 in distance, since anything smaller is irrelevant. (I included J0 because I am a heretic on that score... I allow J0 drives IMTU.)

On multiple jump
If I understand Chris correctly, his basic assumptions will include that the megacorps will simply skip such requisite empty systems by either using drop tanks, longer jumps, or fuel aboard for multiple smaller jumps (demountable or collapsible most likely), whichever suits their current financial needs.

Establishing a population is often not going to be cost effective for a corporation.

For a government, however, it may be a different matter, since the bottom line considerations are very different.

And, to be honest, I can see the point quite easily.

Not every mainworld needs to be inhabited.

Chris Thrash:
[snarky]Or, Chris, FT isn't Traveller... It's GURPS. [/snarky] BTW, GTFT is the official trade system for GPD now... Congrats.

Seriously, tho', most of us DO NOT WANT multiple jumps for inhabited world to inhabited world to be required. Many of us also don't want the massive-trade-flows imperium GTFT produces/derives-from.

Some of us even want to go so far as proto-traveller-style no-intentional-long-range-trade-exists but short-range-spec-exists models that work in 3d.

What many of us want, in short, is to do as little violence as possible to the fundamental assumptions of Marc Miller, as we each see them. (which varies wildly).

Bk 2 and T20 define what trade in traveller feels like to many. Sorry you disagree.

Sure, it's NOT your cup of tea, Chris. But it's what Traveller is to many. So, please, don't take it out on others that they reject your ruleset.

You and I both rightly get accused of "preaching" our economic paradigms. BTL already isn't interested in either, and I've tried to keep my comments here restricted to the fundamentals which are cross system since BTL objected.

 

[BetterThanLife]

Originally posted by thrash:
</font><blockquote>quote:</font><hr />Originally posted by BetterThanLife:
That means a trip from one port to another is going to take, typically, 15 jumps or 135 days, which is just over 19 weeks.

This is really getting frustrating. I'm trying to not take my frustration out on you, because I can see that it's because you simply don't understand and not that you want to be difficult.

Look: density is not distance. If I drop the average density by a factor of 15.8, I only increase the average distance by a factor of the cube root of 15.8, which is 2.5.

So instead of the average voyage taking 14 days from portcall to portcall, it now takes maybe 30 days: three jumps, with two intermediate stops to refuel.</font>[/QUOTE]You are right, I am messing up here, unintentionally, but my math skills have obviously gotten fuzzy. (3D math was so long ago and hardly used since, I am relearning things as we go for some things and learning new things as well. Thanks for that.) However if only one planet in 15 is habitated, it feels like you would have to make, on average quite a few more stops in between systems. The fact that it only adds a stop or two in between intuitively feels wrong. Not saying that it would, just that is what it feels like.

</font><blockquote>quote:</font><hr />How do you price the ticket for the trip? High Passage, Mid Passage, Low Passage and Freight.

Per parsec, not per voyage, which is the only way that actually makes sense under any circumstances. The only effect is that the costs to the shipper or passenger are increased by a factor of 2.5 or so, which reduces the overall amount of traffic by maybe a factor of 8. This just reinforces the "frontier" feel of the original descriptions of the Traveller universe. </font>[/QUOTE] I agree that per parsec pricing makes more sense, to ma anyway, however I would prefer that be left up to individula GMs as some would prefer not to change that part of canon.

</font><blockquote>quote:</font><hr />What do you do if your Spec Trade roll gets blown and you don't make much profit on that trip?

Don't engage in speculative trade if you don't have the margin to absorb the inevitable losses.

On the higher traffic routes why isn't some Mega Corp putting in stations at the uninhabited systems and therefore inhabiting them?

They probably would -- so what? The life support costs in canon also imply that maintaining such a station is relatively expensive, which limits their size to a few thousand. As long as the Imperium does not consider these "member worlds" per se, but only "temporary outposts," nothing has changed. They are like the outposts that are currently assumed to exist in the outer parts of most inhabited systems: present, but generally ignored.

With all the wilderness refueling between stops and the ever present chance of a misjump, interstellar trade just got a whole lot more dangerous, without the fact that the Imperium can't even patrol the populated systems, so Piracy is a very real threat on every trip.

Exactly! Suddenly, the canonical existance of pirates and the need for wilderness refueling coincide with the observable facts of the setting, which they don't right now.

Your interstellar trade will be virtually limited to large merchant vessels, that travel in convoy, typically with Naval escort and tanker support.

You mean, like the Gazelle-class "route protectors" run by Al Morai (SMC, p. 31)? Or the reason that the Imperium even allows private merchant ships to be armed at all, when outlawing offensive shipboard weapons would be a clear way to distinguish pirates from legitimate merchants?</font>[/QUOTE]Actually with Merchants getting scarer and merchant shipping getting larger per ship and travelling together 400 ton pirates would either work in packs or not exist. Bigger ships and ships working in concert would be the order of the day. (As a 400 ton pirate is a flea to a large merchantman.) Destroyers, Destroyer Escorts and Cruisers would have to be the order of the day.

</font><blockquote>quote:</font><hr /> the playability of the system would require a total rewrite of the economics to the point where it isn't recognizable as Traveller.

I submit that the result is more recognizably "Traveller" than the current situation.

The rest of your objections either I've answered (above, to Aramis) or are irrelevant because you don't understand the actual effects of distance.</font>[/QUOTE]Perhaps but I am learning. Thanks again for your patience.

</font><blockquote>quote:</font><hr />When you broke the laws of supply and demand, did you expect there not to be any consequences?

Don't talk to me about supply and demand unless you're willing to discuss Far Trader-style economics. The rest of Traveller is manifestly broken in this regard. </font>[/QUOTE]Actually I was just paraphrasing your tag line. It was meant in fun.

But since Gurps never interested me. I actually never even knew, until after I purchased T20 and went in that direction that SJG had even published any Traveller material since their 15mm Cardboard heros. (Which I do own.) Since they use an alternate history, and history, IMHO, is what holds the OTU together, I have pretty much ignored their material. Since MWM has stated that their material is alternate canon and since I don't own much of their material (mostly because of that and the fact that many of the key books are out of print) I am incapable of discussing the merits or lack thereof of their material.

 

[BillDowns]

Guys, I've been reading the posts, but not contributing for several reasons.

First, I think you have discovered why MWM doesn't want to mess with 3D and still try to keep to game design. It doesn't appear to work.

Second, why does sector, subsector, whatever, mapping need to be 3D? Whats-his-name at Project Rho has a very good discussion on this. somwhere - you'll have to look for it.

Just curious.

 

[BillDowns]

Originally posted by thrash:
</font><blockquote>quote:</font><hr />Originally posted by BillDowns:
Second, why does sector, subsector, whatever, mapping need to be 3D?

Because canon refers to those divisions, separate from their purely astrographic functions.

Whats-his-name at Project Rho has a very good discussion on this. somwhere - you'll have to look for it.

Save your patronizing. "Whats-his-name at Project Rho" is Winchell Chung, whom you would have seen us all quoting if you had been paying the slightest bit of attention. How do you suppose "rhombic dodecahedrons" came into the discussion? </font>[/QUOTE]I wasn't patronizing, I couldn't remember his name and really feel like searching a 7 page thread for it.

Second, lighten up.

 

[TheEngineer]

Hi !

Some questions

Would it need some more alien empires to preserve the "surrounded" nature of the Imperium ?

Or is it intended to take those "empty borders" as frequently missed "frontier areas" (well, as it is seen in previous posts the in border volume already provides a kind frontier feeling) ?

If moving to a 3D TU (or 3D jumpspace) and real star list relations, could something there still be something like the cut off Spinward region ?

Regards,

Mert

 

[TheEngineer]

Hi !

Sorry, mind focusing problems, but I do not really understand 'There isn't much room in the disk "above" or "below" a 140 pc thickness'...
I'm not so sure about the shape of the 3D TU Imperium now.

Do you expect to have large border areas (like the intersection of two spheres) e.g. between the Imperium and the Aslan, or would you keep those areas smaller (a merely careful touching zone between two empires) ?

Its in fact the vast amount of border area (compared to the 2D version), which strikes me most. Guess that needs a completely different amount of naval forces to provide some kind of safety here.

Is there any rough visualisation, how the 3D TU universe could look like ?

 

[BetterThanLife]

We have hit on a couple of options for it so far. Nothng concrete yet. But in general, looking at Thrash's idea and the one I have been toying with, it does retain basic shape. As for more empirse, possible but the areas between empires aren't likely to have anything with much juice. Mostly Pocket Empires similar to the Gateway region is how I see it. (Where three major powers come together.) The longest Contigous border between the Imperium and another hostile power (or potentially hostile power) is the Solomani border. There is the long Vargr border but the Vargr aren't a cohesive power. Now the Solomani have a bigger border with the Aslan, and the K'kree and the Hivers have a nice big border, but in general the Imperium doesn't have that big a border with its neighbors. I figure we could extend those borders a bit and put a bunch of pocket empires around similar to the Gateway Domain, or Fasa's Reavers Deep Sector (What I recall of it.). Which if you wanted to play there would provide a nice frontier feel to it with influence from nearby competeing major powers. I think 6 is an important number to keep.

But that is the traditionalist in me.

Chris is right, with the Galactic disk roughly 300 Parsecs in thickness and things thinning out as we get closer tothe edge taking a big slice out of the middle to the tune of 140-150 parsecs pretty much uses up the disk in the Z axis.

As for shape, I have been topying with a sphere and cutting away sections, for rift, borders etc. Thrash is looking at an oblong shpere. The second issue when dealing with the shape of the Imperium is how to cut it into Sectors and subsectors. In 2D Traveller this is done in a regular draw lines in the sand fashion or on a map regardless of what is actually there. (Kind of like the way the Pope divided the Americas between Portugal and Spain all those years ago.) And those with more systems are more powerful. (Makes sense.) For example Several Subsectors in the Spinward Marches are under the domain of one of their neighbors or split among their neighbors. This may be due to lack of stars, lack of Imperial systems, or the fact that a hostile power controls part of the subsector. We could also compare Ley Sector, but for some reason QLI left out the Subsector Capitals. (OOOPS!)

Once we get the rest of it nailed down then I will be more than happy to generate and post a possibility in 3D. (Which will open a whole bunch of new comments, IMHO.)

 

[BetterThanLife]

Another point since we are using up the disk in the Z-Axis there wouldn't be much above or below the Imperium, certainly not major powers so the Traditional Surronded would still be fairly easy to attain. We have basically eliminated 2 directions so the Imperium could still have enemies all around Spinward, Trailing, Coreward and Rimward. What terms do we use for the Z-Axis?