Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Standard Sci-Fi Battles Using Fluid as the Medium?

  1. Apr 24, 2014 #1
    Hello! I'm working on creating a sci-fi setting for a tactical space combat video game and short story series, and I had a few questions I couldn't find much info on after googling. I'll be playing a little bit loosely with the laws of physics for the sake of gameplay and storytelling, but I also want to avoid blatant violations as much as possible.

    For gameplay purposes, I want to have the possibility of battles that take place within visual range, at relatively slow velocities, something closer to what you see in most sci-fi movies or games than the near-lightspeed sniping matches that I've been told would be closer to reality. I admit I only have a high-school grasp of the physics involved, but could a low-density liquid or gas work for creating enough drag, light diffusion, etc. to make that kind of setup make sense? Essentially, Space is an Ocean / Space is Air, but without the constant downward gravity. The fluid would be contained within a huge but enclosed area.

    I apologize if this isn't the right kind of question for these forums, but I'm not sure where else to try asking.
  2. jcsd
  3. Apr 24, 2014 #2


    User Avatar
    Science Advisor
    Gold Member

    Hi Maroy,

    Most of space combat games pretend there's a drag-inducing medium in space that justifies what is essentially a WWII-style of dogfighting(e.g., the "X" series, the first "Elite", "X-wing" and innumerable others). The problem is that whatever is filling the space would be also self-gravitating(i.e., would collapse unto itself), and most likely quite opaque to light(similar to our atmosphere), so unless you are prepared to use a lot of handwaving it's very much non-physical without an easy way around it.

    But you don't have to sacrifice Newtonian flight model for the sake of gameplay. There are quite a few games that manage to retain the dogfighting experience without resorting to such conceits("Babylon 5: I've found her", "Elite 2", "Elite 3", "Terminus", "Infinity Combat Prototype"). You may want to check them out and see how they handle it.
  4. Apr 25, 2014 #3
    " I want to have the possibility of battles that take place within visual range"

    If you want close range battles, i could suggest employ advanced jammer technologies, so they cant hit each other from afar, and probably they also have troubles with tracking a fast moving target.
    Orbital combat, capturing asteroid mines, theese can be also useful for decreasing combat distance, and give more role to smaller units.

    The plausibility level of Star Wars' asteroid storm isnt very high, unless some giant thing has shattered not so long ago. (Or a new planet is just forming?)
  5. Apr 26, 2014 #4
    Thanks for the suggestions! I hadn't considered self-gravitation; that definitely rules out the fluid idea. The game is more of a small-scale fleet strategy game than a dogfighting simulator, but I guess that would probably a good place to get ideas from. I'll take a look at those games you mentioned, Bandersnatch.

    Jammers and sensor limitations make a lot of sense, considering most detection methods would probably be slower than light anyway. My universe's main hand-wave for FTL is a wormhole/hyperspace hybrid, so I might just give it the extra properties I need if I can't get a more plausible setup working. In normal space, combat will definitely be Einsteinian/Newtonian, with emphasis on orbital mechanics.
  6. Apr 26, 2014 #5
    "considering most detection methods would probably be slower than light anyway"

    Did you mean light speed? Sonars dont work in space. :P

    As far as i know, at this point, they didnt really gave properties to hyperspace, except in W40k, where it is a really bad place...
  7. Apr 26, 2014 #6
    Heat sensors was what I was thinking of, but I forgot that radar and infrared travel at lightspeed. My bad. My version of hyperspace, which the humans call the "Plexus", is very intentionally something that shouldn't exist according to normal physics, and leads to the discovery that sapient beings have a limited amount of direct control over reality.

    ...The more I read my own ideas the more I'm realizing I'm probably just shooting myself in the foot by trying to make 'serious' science fiction instead of science fantasy.
  8. Apr 26, 2014 #7
    Personally i think a good fantasy dont violate the laws of physics in every corner, Lord of rings and Game of Thrones dont have too much magic.
    Of course i cant deny it is tempting to handwave away a lots of stuff...
    (in my story idea i was a bit lucky that i didnt think about ace characters instead of drone operators for example)
  9. Apr 26, 2014 #8
    Sci fi battles are always World War II technology. It looks cool and is exciting.

    The real thing would have no human element. Too slow. How boring is that?
  10. Apr 26, 2014 #9
    It can be interesting from the viewpoint of the captain, there can be more than one justification why dont trust decision making entirely to computers.
  11. Apr 26, 2014 #10


    User Avatar
    Staff Emeritus
    Science Advisor

    There are plenty of space RTS games that ditch Newtonian physics without explaining it and are quite fun to play. It might not be realistic but its difficult for most people to think in those terms given our experiences on Earth. Rather than try to justify it I'd say just go for it. Any explanation is going to require very different physics that will take a while to explain and is more likely to bring the character out of the game.

    Like bander says though there are games that do use it to good effect that you could utilise. There are even board games that have done it well: http://boardgamegeek.com/boardgame/3637/triplanetary

    If you're looking for justification for why long range combat is ineffective you could just say that there aren't any weapons that work well over those distances. Beam weapons might not have the range due to insufficient collimation and projectiles/missiles could be easily seen from afar and dodged or shot down.
  12. Apr 27, 2014 #11


    User Avatar

    Staff: Mentor

  13. Apr 27, 2014 #12
    Fair points all around. Limited weapons and sensor ranges would keep practical combat at reasonable distances while still allowing for fun Newtonian maneuvers, and I could impose some limits on speed from engine and targeting limitations. Most of the smaller craft in my universe are autonomous drones, but they still need human commanders present due to the lack of FTL communication and the importance of being able to second-guess the computer's decisions. I think I'll still handwave the Plexus having friction, to help it feel more alien and to create some interesting tactical situations. On that note, gas torusus would make for excellent places to test ships designed for Plexus travel, thanks for the link.
  14. Apr 27, 2014 #13
    I’m a veteran of early 1980s attempts to reconcile such visual experiences as those in the movies Star Wars: A new Hope and Star Trek: The Wrath of Khan with both real physics and gaming, pen and paper and computer-assisted P&P games (especially the old Starfleet Battles hexboard game) and video games (the only one of much substance I ever wrote was a networked automation of the P&P Vector 3), so am something of an old hand at this problem. Here’s a distillation of those old efforts:

    The first major problem is movement. As countless SF netzens and film buffs have discussed at length, the makers of STrek, SWars and their countless imitators based the movement of spaceships and projectiles on a mixture of observations of boat, submarine, and aircraft movement, which takes horrible science apologetics to make even the sloppiest sense of. I’ve encountered ideas ranging from elaborate schemes where the vehicles aren’t actually moving in a smooth Newtonian way, but making fast sequences of short, nearly instant “jumps”, to hand-waving pseudoscientific mentions of “etheric wings”, none of which inspired me with other than a desire to steer well clear of them. So my best resolution of the movement problem was pretty much straight, realistic physics: assume the vehicles move just like real spacecraft, except that they have much more stored energy and reaction mass, so can accelerate at rates that present-day spacecraft can sustain only a few times for brief periods. SPI’s Vector 3 game, handled this well and simply enough for quick gameplay using calculator-free arithmetic and game pieces on a pair of square boards to give a 3-d display. Though not until the 1990s, and they’d be lax in sticking to it, the makers of the Babylon 5 TV series made an effort to have spaceships move realistically.

    The next problem is seeing one another. This struck me as an easy one, as we already have radar that can accurately detect spacecraft and missile-size objects at the distances and speeds realistically moving spacecraft can achieve in a few hours or days. Simply take as given that folk aren’t really looking out of cockpit windows, etc, but rather looking at computer-generated images combining known shapes and colors of spacecraft with radar data, perhaps neatly displayed on cockpit windows.

    The next problem is spaceship hitting one another with anything, or otherwise damaging one another. My resolution of this was two part:
    1) as with present-day aircraft combat, most of the “shooting” would be of self-guided missiles, essentially small spacecraft capable of high accelerations for short durations;
    2) projectiles would not be single solid bodies analogous to bullet, but “swarms” of multiple impactors analogous to shotgun pellets.
    I imagined the two parts combining to give missiles that exploded before impact into swarms of impactors and munitions that people thought of as single projectiles that were actually small short range missiles that broke into impactor swarms. Variations such as the impactors being super-heated by the explosion that produced them can be used to explain the visibly glowing bolts seen in the SWars and STrek movies.

    The last big problem is that, in most stories and games, for dramatic and gameplay reasons, you want your spacecraft to be able to survive a few hits, using something analogous to armor plating or the gradually depletable shields in STrek. My resolution of this was two part:
    1) passive armor similar to present day armored vehicles, an advanced, laminated kind that ablated to absorb the projectiles’ energy;
    2) “active” systems that detect incoming projectiles and shoot them just before they hit with swarms of similar projectiles. This idea appeared in the “beehive armor” of the 1970s Ogre/GEV P&P boardgames.
    Last edited by a moderator: Apr 28, 2014
  15. May 8, 2014 #14
    "The next problem is spaceship hitting one another with anything, or otherwise damaging one another. My resolution of this was two part:
    1) as with present-day aircraft combat, most of the “shooting” would be of self-guided missiles, essentially small spacecraft capable of high accelerations for short durations;
    2) projectiles would not be single solid bodies analogous to bullet, but “swarms” of multiple impactors analogous to shotgun pellets."

    I also thought about such stuff as main attack weapon. While point range defence is essential against them, i also considered manueverability an important factor, since even when the missile is hit, it can still erect a swarm of kinetic penetrators, and you have to dodge, otherwise, at least your outside sensors and defence systems are ruined.

    I think larger craft are better then a squadron of smaller crafts in deep space, roughly 1.5 times better.
    In case of orbital combat, either you divide the fleet and waste half firepower, or have to fly close... stripped from superior laser range (that can jam or blind sensors, but isnt the main attack weapon), the smaller crafts can overwhelm the big one, also more spacecraft can be more places at once if you have to deal with minor enemies, light frigates, privateers, rebellions...

    So both large and smeller ships are needed IMHO.

    About detection : i wondered about one thing. In Rise of Leviathan, there were a few stealth ships, described as a strategical, rather than tactical weapon.
    Yes, i know, due to the laws of thermodynamics, you cant contain your waste heat forever, its not like you have to contain it for a few minutes or hours, let alone hide the flames of the thrusters...
    But i would be a bit curious, what can be the efficiency of using liquid helium and magnetic cooling to contain your waste heat, then trap it with some endoterm reaction?

    (Yes, there were already some posts about the implausibility of stealth in space, there were even an article, although the one on atomic rockets seems to be exagarrating things like time needed to scan the entire sky ...
    However, even if you cant stop a ship from being detected, what if one can contain waste heat enough, and take the proper vector in the vicinity of some hot body, so the ship might be rather classified as a new comet?)
  16. May 12, 2014 #15
    That's exactly how I feel about most of this stuff -- you really don't have to explain it. In SF we almost feel obligated to as a way to stay true to the genre, but we're so used to suspending disbelief and thinking in the extreme abstract that I think readers/audiences are willing to accept any world that has internal logic.

    Take, for example, zombie movies and The Walking Dead. The smart writers don't get too close to an explanation for corpses reanimating, and audiences can accept that as long as the internal rules are followed -- a bite means a person will turn, only a headshot will permanently put a zombie down, etc. But if suddenly a wizard joins Rick Grimes and co. in the fifth season of The Walking Dead, and he starts hurling fireballs and lightning around, it would violate the show's internal rules and turn a lot of people off.

    Likewise, George RR Martin's never explained how seasons in Westeros can last decades, BSG never explained how its battlestars were able to literally teleport in space, and steampunk novels don't get into long, detailed explanations of how steam and gears can animate a robot or keep a city floating in the sky.

    While it's awesome to try staying faithful to hard science as much as possible, the vast majority of readers are more interested in the characters and events than in possibly long infodumps on the underlying tech.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook