Sci-fi Military Tactics and Strategy

All while being shot at, presumably?

You probably won't have to. A flyby will have you in shooting range for only a couple minutes and even if you loose your engines you'll drift with the rest of the fleet who can assist you. Another pass might take hours to happen as ships have to brake and re-accelerate or continue until their orbits bring them back together.

Push comes to shove you can tether the entire crew together, walk out that airlock, and jump so a friendly ship can retrieve you.

Edited by Belisaurius on Aug 26th 2019 at 4:30:41 AM

Flyby? Oh, right, we're talking about short-range, "dogfights in space" combat, not realistic combat. Or are we saying that fleets will be in effective range of each other for only a few minutes given relative velocities? That's at least somewhat reasonable depending on weapons technology.

Edited by Fighteer on Aug 26th 2019 at 4:31:54 AM

Keep in mind that if you're in Earth's orbit you're looking at a minimum speed of 7 km/s or a maximum of right under 11 km/s you could easily have fleets on opposite orbits closing at 15-20 km/s and that's assuming we haven't left Earth's orbit. I suppose you could snipe at eachother with long range missile salvos but you're looking at saturation tactics trying to overwhelm enemy point defenses. A damaged ship could easily be protected by other ships in that formation.

If you’re in orbit there’s not really anywhere that’s going to be out of weapons range. Striking targets on the opposite side of the planet isn’t too hard.

Orbiting Earth in opposite directions, you wouldn't need to shoot missiles at each other. Direct impacts at 15 km/s would do the job nicely.

If you think about it, a missile launched against a ship's orbital vector wouldn't fly around the Earth; it would deorbit. Launched ahead of the orbital vector, it would tend to rise to a higher orbit instead. Such fights could only be held at close range since the missiles' propellant, and thus their ability to correct for these orbit changes, is a finite resource.

That said, it's unlikely that opponents would all be in exactly the same orbital plane and inclination, so exchange of fire would have to involve velocity changes for the projectiles to hit their targets at all.

Edited by Fighteer on Aug 26th 2019 at 5:00:54 AM

@Flighteer: I wanted the game to be as hard as possible. Ships take up parking orbits and take potshots at each other as they swing by. One tactic is to mine the enemy's orbit, and my first question was wether or not it's worth it to have misses decelerate and become space mines.

Edited by dvorak on Aug 26th 2019 at 7:41:35 AM

Okay. But you have to remember that any change in velocity doesn't make you go "faster" or "slower"; it changes your orbit. Slow down and your orbit becomes lower. Speed up and your orbit becomes higher. To "mine" an orbit, you have to stay in that orbit, meaning you have to stop accelerating, not stop completely. There is no such thing as stationary while you are orbiting a planet. If you aren't moving horizontally, you're moving vertically.

Edited by Fighteer on Aug 26th 2019 at 5:49:25 AM

Geostationary orbit is a bit of a misnomer after all.

the thing is though, if Sci-Fi followed just a BIT of physics instead of just making shit up, they could do some really really neat stuff, but alas, most just Rule of Cool it.

Edited by Draedi on Aug 26th 2019 at 2:34:24 AM

@Bel: "But all this takes a while."

Ha, that's just like saying since warships carry lifeboats, sinking isn't a concern. We don't know what combat in space will be like, but ideal conditions will seldom prevail.

And yet it's also a perfectly accurate descriptor at the same time. In a geostationary orbit, both you the orbiter and the planet you're orbiting appear stationary relative to each other. If you're in geostationary orbit, the planet doesn't appear to turn even though the backdrop of stars behind it will move. If you're on the planet, an object in geostationary orbit doesn't appear to move from its position in the sky even though the backdrop of stars all around it will.

If we're talking about something moving at absolutely zero meters per second even down to the particulate level (aka Absolute Rest), that's impossible as there's always something influencing or inducing motion upon something else.

Even "Absolute Rest", if such a thing were even possible, doesn't say what you are at rest relative to. Zero temperature is the closest thing to rest any object can come to in an inertial reference frame, and the Heisenberg Uncertainty Principle prevents anything from being at absolute zero. Quantum fields always have some energy, for this same reason, even if their average energy in a vacuum state is zero. (Note that the Higgs field has non-zero vacuum energy even given this.)

Edited by Fighteer on Aug 27th 2019 at 2:23:56 PM

Anything, everything. Absolutely zero motion at any level relative to anything.

Which is impossible owing to even simple influences like the long reach of gravity. Nothing with mass can achieve Absolute Rest, just as nothing with mass can reach the Universal Speed Limit aka speed of light. It's all part of the (mathematically) hyperbolic nature of the Universe. Just as it requires an infinite amount of energy for a proton to reach exactly 300,000 km/s, there are an infinite amount of sources which influence a particle away from Absolute Rest.

I think you're being a bit too philosophical about it. Simply put, everything is in motion relative to something, but equally everything is at rest with respect to itself. The most fundamental concept of relativity is that all inertial (non-accelerating) reference frames are identical: that is, from your perspective free-floating in space, you are still and everything else is moving around you. This is true no matter where you are or how fast you are moving.

Aside: You could, hypothetically, define a "universal zero velocity" relative to the cosmic microwave background, but it wouldn't be useful for anything.

The speed of light is often misunderstood as well. It's not a cosmic speed limit in the sense that something puts the brakes on your car when you reach it. If you have any mass at all, no matter how fast you go, you are infinitely far away from the speed of light, in all directions. If you accelerate to 0.99999c with respect to Earth, you are no closer to light. You have just as far to go as you did at the start.

Edited by Fighteer on Aug 27th 2019 at 10:50:26 AM

"Ftl is sci-fi's dirty little secret..."

I was going to use wormhole gate/Gauss catapults to facilitate extrasystem travel because I'd read that it was the only way to get "ftl" without breaking physics.

Edited by dvorak on Aug 27th 2019 at 8:16:22 AM

To be absolutely clear: any form of FTL breaks something about physics as we know it, but that doesn't mean you can't use FTL in your story.

The current methods of "realistic" ftl aren't even really going faster than light, just "shortcutting their way there"

And even those create some problems with causality. For example, it's possible to construct frames of reference in which an Alcubierre drive ship would literally travel backwards in time, and by implication the same would apply to wormholes. There's also the problem that, given what general relativity predicts about wormholes, nothing made of matter could traverse them intact.

Edited by Fighteer on Aug 28th 2019 at 9:10:29 AM

Of course this is all with our current understanding of physics. We may hit upon some miracle solution in the future and suddenly the galaxy is ours.

Or we experiment with some kind of FTL drive and find out things like causality as we know it are complete bunk.

It wouldn't be the first time in science that something we were absolutely certain about gets disproved.

and : stipulated. I've said many times that science fiction explores what could be, not what we know to be, and it's completely fine to discuss FTL in that context. It's just that you run into challenges when you try to justify it in terms of known physics.

Some very smart people have speculated how sci fi could include ftl without violating causality: Here for example:

"And a post here from last year which noted that contemporary physics has just barely left the door open to FTL, subject to certain constraints. The relevant effect of these constraints - as I understand it (and General Relativity is not my field of expertise) - is that you can stay out of temporal trouble so long as your baseline FTL routes do not cross-connect."

Kind of feels like you're trying to cheat the rules by keeping the referee from noticing.

I mean FTL is already cheating, and our current knowledge of the most likely forms of FTL are pretty much cheating to a high degree.

Okay, this is me being pedantic, but you're triggering my pedantry button, so you have to deal with the results.

Nothing can "cheat" physics. Physics is the rules of the universe. If it is possible to do, then it was never against the rules to begin with. We just didn't understand the rules well enough.

If you want to write hard sci-fi that breaks the rules as we know them, then you should at least hand-wave that the latter sentence applies.

Edited by Fighteer on Aug 28th 2019 at 2:36:15 PM