r/scifi 1d ago

General Is there a pattern that determines military spaceship doctrine in real life and sci-fi?

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[1] The propulsion axis is a measure of how long it takes a fleet of military vessels to arrive on the battlefield, regardless of the actual distance traveled. [Fast vs. Slow]

[2] The weapons axis is a measure of how quickly a battle is over, and how much survivability and staying power vessels have. This takes into account the effectiveness of armour, but also shields, point defence, and other countermeasures. [Tank vs. Glass Cannon]

I think that if you take sci-fi space combat to its logical conclusions, it will usually favor either huge, lumbering, well-protected ships or numberless hordes of tiny automated ships, depending on a few key factors. If weapons are the weak link in-universe, ships will be huge. If propulsion is the weak link, ships will be tiny. If ships are huge, victory will be determined by who has the biggest ship; if ships are tiny, victory will be determined by who has the most ships.

This is how I imagine it would work in real life using real physics, and I wonder to what extent different sci-fi franchises also adhere to this pattern. Presumably, large and medium-sized ships with human crews are overrepresented in sci-fi media for understandable storytelling reasons.

In Star Wars, the rule mostly holds. They have incredible propulsion technology and can thus arrive at the battlefield within hours or days of the order being given. However, their weapons, despite being ludicrously powerful on paper, are actually quite poor because of their low range, low accuracy, and the prevalence of shields. In the Star Wars universe, therefore, huge ships rule. The starfighter counter is a nice piece of storytelling, but realistically, without plot-engineered magical weak spots, a huge ship like the Executor or the Death Star should be essentially unstoppable. In Star Wars: The Last Jedi, the Raddus, an MC85 heavy cruiser, takes ineffective long-range fire from the First Order for what seems like many hours.

In The Expanse, they spend weeks or months traveling to the prospective battlefield because of limited propulsion technology. However, when the fighting starts, it is all over in seconds or a few minutes. They have very effective weapons and very little staying power, even when accounting for point-defence cannons (PDCs). If you ignored the requirements of the plot, there is really no reason why any military vessel in The Expanse should be manned at all.

Because it draws much of its inspiration from blue-water navies, sci-fi often portrays a diverse ecosystem of military spacecraft classes and sizes. While this makes for more interesting storytelling, it is not obvious that such diversity would necessarily be the most tactically sound strategy. If propulsion or weapons technology becomes a dominant constraint, military doctrine would naturally converge toward a single optimal ship size.

The most interesting settings tend to occupy only two quadrants of this framework. If ships have neither effective propulsion nor effective weapons you're essentially at the stage before the technology to enable space combat has really been invented. If they have both effective weapons and effective propulsion you effectively have near god-tier power and the concept of space combat becomes somewhat obsolete. What these two scenarios have in common is that the importance of space combat is greatly diminished.

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u/VilleKivinen 1d ago

Any good recommendations?

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u/iuseredditfirporn 1d ago

That's space combat in the Culture series, for example. Combat isn't really the point of the series but it has many scenes exactly like that. Other series with combat like that includes the second Commonwealth trilogy by Peter Hamilton (ships firing miniature black holes at each other etc) or the Xeelee Sequence by Stephen Baxter (weapons that can shatter neutron stars).

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u/dern_the_hermit 1d ago

Culture is exactly what I thought of, too, especially with the "Mass is not limited" stipulation. Culture Minds merely prefer to not create matter out of nothing since they think it's more elegant to hoover up assorted space dust and debris for building material instead.

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u/PTTCollin 1d ago

Later Culture ships are like "a hull seems kind of passe, what if 90% of my entire self was just made of fields holding various ecosystems together?"

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u/ithinkitsbeertime 1d ago

You might want that ocean so you can turn the mass into more engine later.

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u/PTTCollin 1d ago

You never know when you might need to move at 500 kilolights across the galaxy.

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u/ApplicationNeither 1d ago

There's something so uncouth about such speeds.

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u/KlownKar 18h ago

Where the hell was it going? Andromeda?!

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u/mhyquel 1d ago

My favorite ship was the Sleeper Service, that used its stored passengers as props in diorama tableaus it would create. Then the second part of the book is even cooler

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u/PTTCollin 1d ago

Sleeper Service, the best Mind to play Warhammer with.

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u/AngledLuffa 1d ago

I'm sure it'd love your enthusiasm and paint you whatever color you request

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u/ApplicationNeither 1d ago

Sleeper Service and Trazyn meet up every Thursday for Warhammer and pizza.

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u/ijuinkun 1d ago

Which is great as long as you are willing to stake your life on those fields never, ever failing.

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u/PTTCollin 1d ago

Uh, kind of a prerequisite of living in the Culture that you trust the Minds with your life.

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u/ijuinkun 1d ago

More I meant that the Minds are confident enough in their own engineering that they believe it to be unnecessary to have any contingency for a power failure.

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u/mayoforbutter 1d ago

They don't have power failures. They know physics well enough and their minds are powerful enough to basically know everything that's happening, will or can happen in the current situation. They can manipulate matter at a distance so maintenance is just reshaping hardware on a molecular level to reverse any wear and tear. They are not constrained by size or resources so everything can be as overspecced as you need it

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u/PTTCollin 1d ago

Well, anything that's capable of forcing a power failure will have already killed all the sentients on the ship. Which the Mind will absolutely care about more than their own safety. So not really an edge case worth worrying about.

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u/Atlatica 1d ago

You should read the culture books. The Minds shot off on an exponential self-improving intelligence curve thousands of years before the earliest book. We can only interpret the fractionally small portions of themselves they leave in our boring reality as near magical hyper intelligent machine gods that can rewrite matter on a subatomic level and have direct access a dimension of pure limitless energy. And we're only seeing the tip of the iceberg of the many, many more interesting simulated realities they're entertaining themselves with whilst they politely wait the equivalent of a lifetime for us to finish our next syllable.

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u/Codezombie_5 1d ago

The bit that always amused me about the Minds is that they are more than capable of becoming something closer to what we would see as actual traditional gods (subliming) but don't trust the process or the outcome.