Another look at dynamic story generation for computer role playing games

I've taken a wildly different direction with the Dark Stars Traveller theme, and am currently working on a roguelike CRPG called Snapshot.  As a work in progress it is coming along fine, using the excellent LÖVE 2D game framework for Lua.  As it is intended to be a CRPG, the notion of missions/quests/adventures automatically comes into play and, as a roguelike game, the automated generation of them becomes an important goal.  So, I've revisited the past and dug up a 1996 paper I had started when I last spent serious time on the topic.  The essential portion is republished below.

The dynamic plot element node logic theorem

January 14, 1996

by Brian L. Price

Part I. Hypothesis

A story can be expressed as a combination of three plot scopes; the master plot, the sub-plot, and the random event (or micro-plot). A master plot consists of a dozen or more significant scenes spread, on average, widely through the story’s time and space. Generally, the master plot begins near the beginning of the story and continues through to the end. The master plot is the main story line.

The main difference between a synopsis and an actual story is that the synopsis covers only the most significant portions of the story, in other words, the master plot. Thus it can be stated unequivocally that a story consists of more than the master plot. One of these other ingredients is the sub-plot. A sub-plot is a short story interwoven within the confines of the master plot. Although most sub-plots are related to the main plot, the relevence of the sub-plots vary even within the same story. A sub-plot typically consists of less than half a dozen or so significant scenes and is expressed in a time and space scope significantly smaller than the master plot.

One difference between a novella and a novel is the drastic reduction with the novella form in the number of seemingly inconsequential events interspersed throughout main and sub-plot alike. These events can be described as random events or micro-plots. These micro-plots typically have a scope of only a single scene and have only minor relevance to any sub-plot or master plot serving mainly to add color although occasionally effecting plot direction.

A reoccurring component of master plot, sub-plot, and micro-plot alike is the concept of a scene. A scene can be expressed as a story node, and a story can be viewed as a sequence of interconnected nodes. Furthermore, these nodes can be subdivided as to ownership by master plot, sub-plot, or micro-plot. Each scene, or node, is composed of a collection of elements. Not all scenes possess all elements, but all scenes are expressible as a subset of a common set of plot elements.

A somewhat arbitrary choice of basic plot elements can be made to form the common set of plot elements. The current plot element node logic theorem holds that these elements can be defined as setting, character, information, features, and events. The element setting can be described as the physical surroundings in which the scene occurs. The character element consists of the characters and creatures which are within the setting during the time the scene occurs. The information element consists of knowledge which may be obtained by or imparted to a character from some other element during the course of the scene.

Features are generally immovable physical objects within the setting which have some special significance to the plot and which may be accessed and/or activated during the course of the scene. Events cover a wide range of elements which may exist or occur within the scene and perhaps beyond but which are usually beyond the control of any of the characters, this covers elements such as weather, war, natural disaster, etc. Of course, the scene would not be complete without resolution, that is, the interaction between the various elements during the time frame of the scene.

Given that:

a. Any scene can be described in terms of a subset of the set of plot

elements together with the interaction between them.

b. Any plot can be described as a sequence of scenes,

c. Any story can be described as a collection of plots.

Then any static story can be completely described using plot element node syntax.

Assuming this to be true, a dynamic story, that is one where the various plots have multiple possible paths, could also be described using plot element node syntax if, and only if, a system of logic was developed that could express the relationships between the plot nodes in a non-deterministic form. That is to say, a system of logic which could resolve the various scopes, probabilities, exclusions, and dependencies between various plot element nodes in such a way as to allow character action and story universe mechanics to determine the plot path, and thus the story’s evolving reality.

In a dynamic story, each plot node (or scene) has a number of defining states or boundary conditions. A plot node has a region of space in which it can occur, a frame of time in which it may occur, a probability of occurrence, a uniqueness factor, and an existence factor. A unique node may only appear at most once in a story. An existent node’s setting and possibly its feature(s) or characters may be revisited. Existent node events which are of a persistent and regional or global effect will alter the reality state of the story universe for their duration.

Still, in order to form plots, relationships between plot nodes must be defined. The primary relationships are: exclusion, dependance, time frame acceleration, time frame deceleration, probability increase, and probability decrease. That is, the transition from non-existent to existent of one plot node will: cause the removal of all plot nodes which are related to it by exclusion, the existence of all dependent plot nodes, a time frame shift toward or away from the present for all plot nodes related through time frame acceleration or deceleration, and the alteration of the probability for future existence of all plot nodes related by probability increase or decrease.

The primary mechanism for bringing a plot node into existance is that of main character action and present plot node resolution. All plot elements except setting can possibly trigger the existance of a plot node or alter plot node boundary conditions. A plot thread is defined by the set of possible existence triggers and dependencies within the starting plot node and possibly at each subsequent plot node within a main or sub plot. These triggers can be represented by a change in plot element condition, ie the death of a character, the gaining of information, the activation of a feature, etc.

Plots become defined as their starting nodes come into existence and, one by one, all but one reality thread eliminated. (A reality thread being a sequence of plot nodes.) The relationship mechanism described herein automatically allows for maintenance of story integrity and proper interaction between main, sub, and micro plots. Application of this theorem to computer games should provide sufficient dynamic plot complexity so as to prevent most players from guessing the game future even after many replays.

Now I realize the above isn't a proper theorem, merely the first steps towards one.  Likewise there has been a lot of progress in the general field, yet still the central problem I encountered 17 years ago remains today.  That is, how to create a friendly and usable authorship tool usable by non programmers so that they may express dynamic stories using such a framework as hinted at above.

I look forward to hearing any comments, suggestions, advice, links, etc.
Thanks,
Brian

Restart derailed

Well I was warming up for a restart and continuation on the Dark Stars ATU, but I've been derailed by a head on collision with the board trolls and incompetent staff at the coti forums.  My first forum ban ever! 

If, or perhaps better when, I resume working on this project, I believe it best to move away from the Traveller baggage to another game system.  Perhaps finding or even creating a community a bit more favorable to the Dark Stars idea.

Anyhow, Happy New Years everyone!

Once more into the breach

I'm feeling like a Quixote type character in pursuit of hard science fiction Traveller space opera instead of windmills.  So far I've examined a variety of different options, some offer to solve the problem by throwing out half or more of existing Traveller works (adventures and such), others just don't make the bar for one reason or another, still others may require quite a bit of work refactoring trade and commerce even the value of a credit, finally there are a few that would sort of work but for one reason or another I just don't like.  My last post concerned one such option, basically redefining the Traveller Jump drive operation to allow for the wilderness option.  I'm still unsure as to the side effects of that option and it allows for the 'go anywhere' ftl style I really don't like.

Once again I'm drawn back to the Lares fixed point ftl and keyhole drive option.  Accepting a certain degree of increased travel times and interface costs seems unavoidable.  While earlier I examined the options of extending the handwave of ftl into a sort of slow stutterwarp or fast microjump those solutions felt clumsy.  One option I've avoided examining very closely is that of extracting the underlying whatchamacallit in the handwavium ftl, defining its effects, and extending it to other technologies such as reaction drives.  Traveller does this with practically every handwavium technology and also shows the pitfalls inherent in doing so; chief among them the tendency for handwavium creepage leading to setting domination.

I've discussed this with a friend who pointed out that extending the handwavium to incorporate the core technology whatchamacallit of the game Mass Effect would solve most of the problems.  While I don't disagree that it is an option, I don't like the direction it leads.  However, while considering it, I did think a bit about the handwavium of the Quantum Skip drive.  The basic idea is that using a rather large but extremely short pulse of energy in a controlled fashion we somehow are able to distort the local frame of space time and trigger a quantum effect that does the actual work.  Might earlier experiments along those lines have been aimed at increasing reaction drive Isp?

Now at some absurd tech level with 99.99% efficiency we might create a drive with an Isp as high as 2.93966571 × 10⁹ or 816,573.8 G-hours of thrust per ton of fuel.. yeah.  Of course even with 99.99% efficiency, generating any significant amount of thrust would require our ship to basically be all radiator to avoid vaporizing moments after engine ignition.  The stock answer to the Isp, thrust, and heat issues seems to be either ignore it altogether or assume some handwavium to allow heat levels in the engine that would vaporize any known material nearby instantly.

Looking back to the math hacking I did the other day in 'An Ode to Simplicity', we can see that extending travel time for the trip between planetary orbit and ftl point to around two weeks each way brings us into the realm of plausible 3He2H magnetic bottle fusion engines.  Well plausible to some.  Call me cynical but we've seen fusion power as being on the near horizon for forty years now and really we don't seem to be much closer than we were shortly after starting.  Then consider that turning a magnetic bottle fusion reactor into a rocket engine is at least one hundred times more challenging in engineering. 

The next 'breakpoint' seems to come at around 49 days each way, with 0.05 m/s^2 of thrust as we could reasonably expect from an advanced magnetoplasmadynamic drive.  Each transit would require about 212.1km/s delta-V, so to meet our 50% fuel load requirement we'd need an Isp of about 61200 which could also possibly be expected from the same drive.  I like this point except 49 days is nearly 50% over what I'd really want to see as the maximum average.

My ideal drive would have a 27 day transit time (x2 = 54) and the same 50% fuel load requirement.  This would require a constant acceleration of 0.17 m/s^2, a delta-v of 386km/s per transit, and an Isp of around 112000.  This is a substantial improvement over our advanced magnetoplasmadynamic drive and may be past the capabilities of even advanced technologies based on known physics.  On the other hand I have some oddball ideas, totally fictional of course, but what if you combined a NTR with a VASIMR?  What if there was some quantum handwavium along the lines of the Quantum Skip drive technology that, in an earlier form, allowed some higher powered 'pulse mode' operation?  At the same time, the acceleration/Isp requirements for this level of performance seem to be well within the range of plausible 3He2H magnetic bottle rockets.

Rather than get into detail about 'how it works', I could simply call it the standard deep space drive and let it go at that.  That follows along with the idea in yesterday's post of packaging the interface engine into a simple to use drive package.  I'll call it the AMPR (Advanced Magneto Plasma Rocket).

A different look at Traveller's jump drive

As I work towards creating a more realistic, harder scifi basis, alternate Traveller universe, I've found that seemingly small changes in travel times can have disconcerting effects on trade and commerce.  The problem is that sticking to the travel times in the mainstream Traveller universe makes it impossible to have realistic reaction drives together with fixed ftl points such as Alderson points.  For many reasons I greatly prefer fixed ftl points but not at the cost of realistic reaction drives.

From a hard science fiction standpoint the root objection is the 'matter density' basis for jump drive distance.  While simple to calculate, it doesn't fit with common science fiction requirement of microgravity conditions for ftl drives.  Then there is that whole mess with jump shadowing, jump masking, meh.. not something I want to deal with.

Traveller has two distances of note in regards to jump drive operation, the ten diameter and the one hundred diameter 'limits'. Let's assume a standard density size 8 planet was the basis for the original specification and examine what the gravity gradient is at the limit distances. For the ten diameter limit, that works out to roughly 0.024 m/s^2, and for the one hundred diameter limit 0.00024 m/s^2.

Earlier on I'd tried using the 100D limit to determine a ftl gravity limit but ran into problems in that the sun in our solar system has a stronger effect at earth's distance than the earth would at the 100D limit.  That is, the sun's influence at 1 AU distance is 0.00593 m/s^2; greater than the 0.00024 m/s^2 influence of earth.  This caused great confusion!

What if instead we say that as long as we are beyond the inner limit of the system's center (normally star) where the gravity influence is less than 0.025 m/s^2 that the nearest planetary body is the primary object of concern.  In other words, the stellar influence is assumed in the ftl navigation calculations but individual planetary bodies have a destabilizing effect on the greater equation.  So, +5 to misjump roll if inside the 0.00025 m/s^2 influence of the nearest planet, +10 to misjump roll if inside the 0.025 m/s^2 influence of the system's center, and +15 to misjump roll if inside the 0.025 m/s^2 influence of the nearest planet.  This is a tad more complicated, though can be easily enough precalculated, and pretty much eliminates jump shadowing.  As for jump masking, phfft, gravity only is of concern in transition between normal space and jump space - problem solved.

With that out of the way, to satisfy the wilderness scenario, we need a suitable reaction drive.  My favorite candidate is the Trimodal Augmented Nuclear Thermal Reactor with scramjet option!  Unfortunately, my earlier version of the TANTR needs reworked to be able to achieve surface to orbit for a standard gravity world.  Let's see what our requirements are; we have three phases of flight - VTOL, scramjet, and orbital.  A rocket normally needs about 10km/s of delta-v for surface to LEO given a standard world.  With an airframe configuration we can probably knock off 1km/s.  For LEO to jump point, lets call it a Brachistochrone trajectory with a constant 5 m/s^2 acceleration.  That will require another 50km/s of delta-v.  Now on the other side of the jump point, we'll need the 50km/s again plus another 1km/s (aerobraking for the rest), this gives a total delta-v requirement of 110 km/s.

Because of needing extra fuel during the vtol and scramjet stages, we'll call our total requirement 130km/s but use our normal cruise mode Isp figure of 1800.   Oh wow, only need 1370 times our payload mass in fuel!  Obviously this won't work.  Ok, lets assume we only supply 30km/s of our delta-v with our TANTR+S engine, that requires a bit over 81% of our ship's total mass.. hmm.. see a problem yet?

If we somehow get back to our original 10km/s for the total surface to LEO and back again delta-V budget along with dropping our Isp to 1200 to reflect the additional fuel load, we find that only 57% of our ship needs to be fuel for takeoff and landing.  Hmm.. rereading some SSTO literature, it looks like the effective Isp of scramjets may be much higher than I'd thought, rather than assuming a lower figure I should be assuming a higher one (than cruise mode).  Assuming that, for a moment, lets suppose 1/4 our delta-v comes from 1200 Isp mode, 1/4 from 1800 Isp mode, and 1/2 from 3600 Isp mode.  So 2.5 km/s from the 1200 requires 19%, another 2.5 km/s from 1800 requires 13%, and 5 km/s from 3600 requires another 13% for a total of 45% of wet mass in fuel.  Obviously these are rough figures!

Now if we're willing to take our time, say 2.6 days, and use a cheaper orbit transfer to jump, we only need an additional 22.4km/s or 81.2% of our remaining mass.. hrrmm that not work either!!  Ok, if we're willing to take 8.2 days!! we only need 7.1km/s and at 1800 Isp that needs 33% of our remaining mass.  Going back and adding in 2x the 7.1km/s figured (round trip) to the 2.5km/s delta-v we needed earlier at 1800 Isp we get about 60% of the remaining mass required in fuel.  Now watch me screw this up - total payload is then 81% x 40% x 87% x 81%  or roughly 23%; 77% of the ship needs to be fuel.

Assuming the above analysis is remotely correct, TANTR+S is a marginal solution for the wilderness scenario and requires an extra couple of weeks in travel time.  This doesn't necessarily kill the idea entirely.  One possibility would be to use the TANTR+S only for the interface and have a higher efficiency drive for the LEO to jump point portion.  At a cost of 5 tons of payload mass, a MPD driven by power from the TANTR+S in reactor mode would have an Isp of 36000.  This would reduce the largest chunk of fuel required to only 2% instead of 60%!  Total payload would then be 55% of the wet mass minus the mass of the MPD.

To make things simpler, I likely need to create standard engine packages that encapsulate the various modes and Isp's into something much simpler to use both in design and in play.  The above process would rapidly drive me to distraction.  Still, it has been a necessary step, coming to better grips with the actual environment before trying to create simpler abstractions of it.

PS: There's a much better look at Traveller's jump drive mechanics and a way of getting out of the stellar jump shadow mess with gravity based calcs here.  Turns out this was a topic on the Traveller Mailing List a long time ago.

An Ode to Simplicity

Simplicity, which by and large we had with classic Traveller's initial little black books (LBBs), is hard to overvalue.  In attempting to achieve the goal of injecting more realism into a hard science fiction version of a Traveller based setting, it is extremely easy to forget this.  Complexity is alluring to some of us, Striker and later, Fire Fusion and Steel, gave us complexity in spades all in the name of realism.  However, as much fun as it can be to mess around with those complex systems, they really don't do much if anything for role playing sessions.  Which is, I think, kind of important for a role playing game.

High Guard gave us what to me is an upper bounds on desirable complexity, still some GM's believe it to be a bit too complex and favor the simpler LBB 2 starship construction rules.  So for construction rules at least, we have examples of workable, usable, upper and lower bounds on complexity.  It isn't an easy target to aim for, let alone hit, when pursuing 'hard science'.

The same considerations hold true for combat systems.  Various Traveller products and adaptions of similar rule sets from other games have given us combat systems that span the range of abstraction levels and the scales of single ship to multiple fleet battles.  Odd thing is, I can't remember, in all my years of role play gaming, ever needing to handle more than small scale battles of a few ships at most in a session and then my players and I were quite satisfied with a more abstract model of movement at least.  More complexity just slows down play, whereas simplicity makes for more enjoyable, interactive, reasonably fast paced gaming sessions.

The same considerations once again hold true for many of us when it comes to skill systems and task resolution systems.  Every time my players and I tried using more detailed skill trees and formally structured task resolution systems, the sessions bogged down into periods of searching through books for skill descriptions, rules lawyering over task resolution, and quickly became roll rather than role playing.  Classic Traveller's LBBs give a good basic set of skills and a minimal set of rules that work quite well.  Nice and simple.  The hardest part seems to be players and GMs coming from other gaming systems that are overly complex and feel lost without all that legal structure.  In the final analysis, once again, simplicity makes for a better game.

This topic has arisen for me because of another game I play.  An open source game, its current crop of developers decided to make combat more realistic.  In the process they've completely broken it and now need an entire new set of additions to get back to the same level of functionality we had in previous versions.  The blind pursuit of realism should never get in the way of the playability and enjoyment of a game.  Seems obvious, but it is a very easy misstep to make when navigating the narrow and rocky trails of game design.

So what does this all mean for the Dark Stars ATU?  Well, once again I find myself waffling.  By throwing out the civilization model underlying Traveller, I can make a playable setting that meets the hard science with one exception criteria.  The problem is that in doing that I've just thrown out half or more  of that body of work we call Traveller.  In the abstract, it works and is quite doable, in reality it bogs down into needing a ton of detail work before it is remotely useable.

In an attempt to avoid the plunge headfirst into a man year or more of background and detail work, I am left with trying to find another solution to the wilderness scenario that meets the hard science with one exception criteria.  As much as I hate it, the process is bringing me back around to giving serious consideration to some form of 'gravitics' pseudo-science.  I really don't like that approach though.  While it solves some problems it introduces myriad others and is at the bare edge of plausibility to qualify as anything remotely hard science fiction.

So I found myself reading about fringe science like the Heim-Droscher hyper-drive.  If you've read much of my ramblings elsewhere on this blog you no doubt realize that I'm a layman when it comes to physics, somewhere around early to mid college level of knowledge - a bit further advanced with mathematics possibly, but I like reading about physics, especially quantum physics.  In the process I've come to discover that our blind faith in Einstein is a little bit misplaced, special relativity shows some fraying around the edges so to speak.  There are other theories.

Yeah yeah I've now lost all credibility with the loyal Einstein is holy camp.  I'll let you in on a little secret, most of them don't understand physics either.  In fact, no one does.  What we have is a collection of theories that fit most observed data within certain error limits.  Quantum physics is bringing everything we think we know into question.

So what does this mean from a science fiction perspective?  Well, for starters it seems a bad idea to tie your shirt-tails to a fringe theory.  Next year someone finally disproves the theory and there you sit looking like yet another casualty of technological progress.  The best advice I've ever read on the subject is to concentrate on the effects rather than the cause.  Say as little about the cause as you can get away with - you'll stay relevant longer and don't immediately set yourself up to be ridiculed by pessimistic no-space-ever fanatics.

Looking once again, hopefully with newly refreshed eyes, at the wilderness scenario (without re-imagining civilization)  we can enumerate the effects of our mysterious scientific advance.

1. It allows for cheap surface to low orbit.
2. It allows for sustained 10 m/s^2 acceleration sufficient for round trips from orbit to ftl point.
3. It allows some form of ftl.
4. The total round trip times for the wilderness scenario closely matches classic Traveller.

I'm tempted to add a fifth element although it isn't an effect, rather the fifth element would be an attributable cause that sounds plausible, can't be easily disproved, and doesn't break proven physics.

In order to address the effects seriously, it is necessary to define point 3 further.  Just what form of ftl are we going to allow?  I'm biased towards the general Alderson Point idea as I think the stock Traveller jump space ftl just opens up too many cans of worms to address with hard(er) science.  In order to address point 4, we need to also define the average normal space trip time under the constraint of point 2 between low orbit and the ftl points.  If we consider the jump points to be non orbiting locations ala Alderson Points, then we need to find the average distance between the average planetary orbit and the average jump point location.

Using the original Lares point/region idea for the first guess at jump point locations places them roughly 0.63 AU from Sol in our solar system assuming a 0.015 m/s^2 gravity threshold.  Assuming we don't want to get closer to the star than absolutely necessary, our maximum travel distance between ftl points becomes just under 2 AU giving an average of 1 AU (keeping things simple) between ftl points.  This works out to a bit over 3 days travel at 10 m/s^2 sustained acceleration.  Our average distance from LEO to Lares point works out to about the same, maybe a hair longer.  Let's call our average wilderness scenario surface to ftl point a 3.5 day jaunt.   Now in stock Traveller each one-way section of the wilderness scenario takes roughly 8 days, so in answering point 4 we need to give our ftl method a transit time of 1 day between systems.   We're back to Lares drive specs again.

Now for the 'fun' part.  Assume for a moment that our maneuver drive is a reaction drive and that 50% of a vessel's mass in fuel will get us through one entire leg of the wilderness scenario.  Now we need a total delta-V of... yikes!  6x10^6 m/s... requiring an Isp of only a bit under 900k.  This is a bit of a problem since it is higher than the maximum possible Isp theoretically achievable with magnetic containment fusion.  That figure is without regards to efficiency loss and material capabilities which serve to limit achievable Isp's to far lower figures.  Congratulations, we've just reinvented HEPlaR.

Hmm.. try for a middle ground?  Abandon the fixed point ftl idea and assume something remotely resembling stock Traveller jump drives but with a lower gravity gradient, say 0.005 m/s^2.  This means that for Earth, Sol's gravity well predominates and the distance to jump point is roughly 13.3mkm distance.  This is about 64 hours constant thrust at 1m/s^2 (assuming midpoint turnaround).  Now we need a much more modest delta-V of around 500000.  Given our desired fuel load, we can get away with an Isp of 66.5k.   While we're now an order of magnitude below theoretical maximums, we're still about two orders of magnitude beyond current projected designs.

We're also neglecting for now the surface to LEO special requirements, but at least we are in the general ballpark with this most recent model.  Our Isp requirements are about twice that of the projected maximums for VASMIR and some pulse fusion theoretical designs.  We also may, however, be too dependent upon the specifics of our solar system for the distances to remain in the ballpark.

Let's aim for a more planetary dependent ftl point distance equation, the catch here is, basing on gravitational gradient, we require a threshold greater than 0.00593 m/s^2, otherwise in our solar system the sun's gravity would predominate.  A threshold of 0.01 m/s^2 works out to just under 200,000 km.  Even at a low constant acceleration of 1 m/s^2 this is only an 8 hour flight from low orbit.  A catch with this is that now surface to LEO delta-V is no longer negligible so our total delta-V requirement is  about 78000m/s, with our desired fuel load we get an Isp requirement of around 11,500.  Ignoring the necessary high thrust component for surface to LEO for a moment, this is comfortably within range of projected technologies and efficiencies.

There are a couple serious problems with this last scenario, it is quite possible that ships would be able to launch ordinance at planetary targets immediately upon exit from ftl for one.  Another is that space battles are, at best, confined to low orbit by the time you make intercept.  Note that the ftl threshold with this last scenario is well inside the Moon's orbit.

When you consider hard science, the ftl threshold parameters get very dicey for any commonly applicable value to yield near habitable planet entry and exit points.  Either you end up entirely too close to the planet for any kind of space battle, or else the entry and exit points are highly dependent upon the nature of the solar system. So, round robin style, we're back to looking yet again at the first scenario with fixed ftl points - dizzy yet?

With reasonable fixed ftl points, we're stuck with either HEPlaR like drives that even with a bit of handwavium break physics, or lengthening the transit times.  Let's take a look at doubling the time first.  We'll make our ftl transits instantaneous and allow a full week each way between average ftl point and average habitable planet.  Using the 1 AU ballpark figure, we need a constant acceleration of, well lets call it 2 m/s^2.  This gives an Isp requirement of around 350000, still pretty hefty but within 3He/2H fusion range.  Up till now we've been ignoring the thrust requirement and have been looking just at the Isp.  Even a measly 0.2g of thrust at these high Isp levels is, quite frankly, impossible given physics as we know it.  It doesn't break physics to have such a device, but no one has a clue how to create one.  Temperature levels are extreme using any straight up design even if all other engineering factors were accounted for.

Just for fun, lets double the time again.  Two weeks each way.  Now we can get by with 0.5 m/s^2 constant acceleration and an Isp requirement of about 175000.  This makes 3He/2H fusion look a bit more realistic but doesn't open any new doors.  Doubling again to a month each way, we get by with 0.1 m/s^2 constant acceleration, and an Isp requirement of around 70000.  Ignoring the 'bang bang' engines due to manufactured fuel pellet requirements, while this doesn't open any particularly new doors for us it is interesting that we're just a little over twice the Isp of a magnetoplasmadynamic (MPD or VASIMR) drive. 

Occam vs Opera - Take 1

What if  Franciscan Friar William of Ockham, known for bringing us Occam's Razor, had applied his tools to minimizing the distance between science fiction space opera and science as we know it?

Harry Turtledove had a leg up on a possible answer in his story 'The Road not Taken", where most of the races in the galaxy discover gravitics and, as it doesn't lead to anything except travel technology, stunted technological growth in other areas.  Most of the races that is except human, but I won't spoil the story further.

At least one fringe of science has drawn a connection between gravitics and FTL travel, the followers of Burhard Heim's theories, in the Heim-Dröscher hyperdrive.  Of course as weird as quantum physics has turned out to be, there may be other possible connections - or then again it might be all a load of excrement.  However, for purposes of space opera, the gravitics-hyperdrive connection is made to Occam's order, one theory to bridge the gap, one piece - albeit large - of handwavium.  This is rather handy since it allows us to engage in that category of science fiction known as 'hard science fiction with one exception'.

Does this mean we can reclassify Traveller as hard rather than soft?  Eh, no not really.  Unfortunately there are too many other pieces of handwavium thrown in.  However, we might be able to use something very much like Traveller (minus a few bits and plus some others) and allow the handwavium of gravitics Heim style to give us the fundamental piece I call the 'wilderness scenario'*.  

*The wilderness scenario is that fundamental part of soap opera science fiction where our protagonist jumps in his spaceship, takes off from one planet, out into space, into hyperspace, back out into space around another star, and lands on another planet.  Then, without supporting infrastructure more complex than can be easily carried aboard to collect and refine fuel, turns right around and goes back to the starting planet.  

Soap opera scifi with a space based civilization

Yes I'm waffling again.  The other day after some conversations I was about to just toss in the towel on the whole idea I'd had originally - or at least started with this time around.  A friend remarked that all scifi soap opera anymore is sailing ships in SPAAAACCEE.  That holds especially true for Traveller, it always has been that sort of setting.

When you start to introduce reality into the picture, or at least physics as we know it, even including some fringe physics, the fundamental barrier between soft soap opera scifi and hard scifi pops up and smacks you in the face.  Initially you might think it is all due to slower travel times but that isn't it, the obstacle is the civilization model.  Soft soap opera scifi concentrates on ye olde planetary civilizations connected by handwaviums.  Handwaviums because otherwise the cost of interface operations (surface to orbit) is *huge*. 

But wait you say, what about beanstalks, laser boosted launch, electromagnetic assists, etc?  Well all of that certainly helps, those solutions reduce the problems by an order of magnitude.  Too bad soft soap opera scifi settings require a reduction of at least two if not three orders of magnitude in interface costs.

Even worse, soft soap opera scifi includes what I call the wilderness scenario:  a relatively small and cheap trading ship that can travel surface to orbit, orbit to interplanetary, FTL between the stars, interplanetary to orbit, orbit to surface - all on one fuel load in a couple weeks time.  A few days later, refuel and do it all over again.   I cannot find a realistic solution to this scenario even with using rather severe handwaviums in the interplanetary realm.

The last attempt with the Quantum Skip drive handwavium and using a somewhat realistic LANTR variant reaction engine still requires 80% of the ship's mass - that's mass not volume - which leaves precious little mass for cargo (as a percentage of ship) in any design that would be even remotely small and cheap.  In fact, it'd be large and expensive, so large that it would probably have to use secondary 'shuttles' for the actual interface. That doesn't completely solve the problem either as now your shuttle has to make numerous trips.

At that point you realize that to keep anything remotely resembling the Traveller setting, you need to throw realistic physics out the window.  Switching to the 2300AD setting helps a bit but still requires more of a handwave than I really am comfortable with for any remote claim to a hard scifi label.  I'll admit it, at a certain gut level I don't care much for the stutterwarp idea.  Perhaps its the feeling that stutterwarp is more of a arm wave than a hand wave.  That and it puts the 'magic' center stage nearly all the time.

Way way back, though unfortunately the documents have been lost in time, I had been working on another hard scifi concept also named Dark Stars.  That first version of Dark Stars was so wildly different in setting that this time around, aiming for a Travelleresque setting, the only thing I borrowed initially was the name.  Well, turns out, maybe I need to borrow far more than just the name.

The original Dark Stars setting was so hard scifi that there wasn't even any FTL.  In it, mankind used what is now called brown dwarfs (and similar interstellar planetary scale objects) as stepping stones to the stars.  The idea came out of some astronomy reports regarding a few isolated but recorded instances of unexplainable obscuration of certain stars, the theory at the time was that the cause was planetary objects between small gas giant and true stars.  I believe this was an early observation of what is now called brown dwarfs.

Obviously in the original Dark Stars setting, civilizations around the brown dwarf stepping stones weren't planetary civilizations.  The setting's back story was that as mankind expanded into interplanetary space, civilization became less and less planetary bound until by the time deep space colonizes were first established orbiting the nearest 'dark stars' there were more people who lived their entire lives in deep space than those who had ever lived on planets.  After that point, planets basically became irrelevant except as possible sources of raw materials that could not be obtained from lesser gravity wells.  Even that slim importance fades away as technology progresses and it becomes cheaper to create heavy elements or replace them with lighter elements than dig and lift them out of a deep gravity well.

One interesting side effect of this model is that planetary defenses and slag weapons become irrelevant.  Another is that it is hard to wrap your head around it as it is so foreign to the way we planet bound think.  Evolution of civilization.

So the original Dark Stars setting ends up becoming a collection of hordes of space habitats clustering around energy and resource points in orbits that minimize the costs.  You might well have specialized facilities in addition to habitats, such as facilities orbiting fairly close to stars in order to turn stellar output into a stored form such as antimatter.  Other facilities might be in low orbits around gas giants engaging in various refining activities.  Yet others are situated near larger rocks or collections of rocks in various places engaging in the processing of raw materials.  Populations, and their habitats, are mobile.  They shift with changing trade patterns and perhaps for other reasons as well.  I'm reminded of the scifi story where I first encountered a form of the stutterwarp idea, hyper-assistance, in Asimov's classic Nemesis novel.  In truth that novel, along with a few others, really laid the seeds for the original Dark Stars setting in my mind. 

That first Dark Stars setting, while interesting, doesn't make for a good space opera on an interstellar scale.  Without FTL and with realistic reaction drives up to and including antimatter, the time scales are rather beyond the space opera norm by a few orders of magnitude.  The question of the hour becomes, what form of FTL would enable near space opera travel times between neighboring stars without widespread changes in the basic underpinnings of the setting?  Further, at what technological point should it become available?  Too soon and the setting doesn't have time to evolve to true planetary independent civilization, too late and the science becomes completely unrecognizable.

Before setting down the operational criteria for the FTL mechanism, it is a good time to realize something inherently different between the first Dark Stars setting and most all soap opera scifi settings.  In Dark Stars a solar system's population and infrastructure is spread out all through the system, with varying densities near various points of interest.  In traditional soap opera equivalent terms this turns every world into a Dyson's sphere!  Traveller RPG is basically a collection of Kardashev I worlds into a Kardashev II civilization; the Dark Stars setting is somewhere between that and a collection of Kardashev II solar systems into a Kardashev III civilization.  Population and energy usage in the Dark Stars setting are almost assuredly beyond those of core worlds in the Traveller OTU setting. 

Along with that, the scale of travel across a 'world' is far different, roughly 5000 to 10000 times greater.  It would be like being restricted to the speed of sail on each world assuming some relatively realistic fusion torch drive is commonly used in Dark Stars for interplanetary scale travel.   This suggests that, to maintain the interstellar civilization soap opera feel, the maximum travel time between two points of interest orbiting adjacent stars should be no more than around three times  the average 'across the world' travel time.  That is, if it takes a month to go from one side of the system to another, it probably shouldn't take more than three months on average to go from a point of interest in one system to another point of interest in an adjacent system.

While a standard soap opera setting can have pre-space flight technology worlds, in a Dark Stars setting that makes little sense.  There is a minimum tech level required to support civilization in space. In order to satisfy the evolution of civilization argument above, this tech level must be significantly less than that required for FTL travel.

In order for space opera style interstellar warfare to make any sort of sense, there needs to be some limitations on the FTL travel mechanism, either some sort of choke points, or some distance limitations, or both.  To allow for manageable multiple star system empires, our speed of information transfer needs to be restricted as well.  In the absence of FTL communications, the time for a packet of information to travel from one system to another through a third is expressible as 2Tt + 2Tc1 + 2Tc2; where Tt is average FTL travel time, Tc1 is communications between decision center and FTL courier, and Tc2 is the communications time between two FTL couriers, assuming that a single courier cannot be used as quickly as two.

If we consider our elapsed time for scale of travel desired and our elapsed time for interstellar communications desired, we can calculate how long our FTL travel between two adjacent star systems should take on average.

Now zooming out a bit to look at the shape of an interstellar civilization composed of a collection of space based civilizations, a few questions spring to mind.  First, what differentiates one star system from another as far as desirability?  Probably a combination of stellar type, availability of easily accessible hydrogen, and asteroid belts - the more the merrier, perhaps small planets and/or moons might also be a bonus as a raw material source.  Beyond that location, location, location.  Of course that depends on the topography of our FTL mechanism.  While still zoomed out at this level, consider the ramifications of the FTL mechanism's topography on interstellar warfare as well.

I'll probably choose the Alderson point-ish Lares region type of Quantum Skip drive as the general FTL mechanism since a bit of time and effort has already gone into it.  It also has a somewhat more hard-sciencey technobabble behind it.  If the FTL points occur at roughly the 0.001 m/s^2 gravity gradient radius, that would put them around 2.5 AU from the sun in our solar system.  That also puts them at a reasonable distance for the average travel time target given realistic thrust levels of high delta-V reaction drives.  Now this assumes that the average interstellar tech level is a bit higher than normally found in Traveller, but given that is also a target criteria, we should be fine.

One aspect of this setting is that it gives us a bit of a way out with regards to our reaction drives and our power plants.  We can sidestep most of the issues with magnetic bottle fusion and go to various forms of pulse mode antimatter initiated fusion. 

I'll have to take more time and consider the pluses and minuses with this idea further.  It seems to give a realistic hard scifi (with FTL exception) soap opera/RPG setting at the price of sacrificing the sacred cow of planetary based civilization.