The Physics of Space War: How Orbital Dynamics Constrain Engagements [pdf]
aerospace.org
aerospace.org
A lot of combat takes place from extremely far distances, using telescopes, rail guns and missiles, and it can sometimes take days for a missile to reach the target (the TV series doesn't play this up as much though, for obvious reasons).
When there is closer combat battles, they are constrained by the G forces humans can tolerate, wear full helmets and de-pressurize their ships, so when the inevitable shots do go through (usually in and out the other side) it's not catastrophic.
There are no force shields, magic gravity generators, lasers (well, except used for point-to-point communications). I found it to be very refreshing mainstream sci-fi.
One warning: after watching The Expanse, the battles in things like Star Wars, Star Trek or Battlestar just look ridiculous by comparison - even with that technology they'd never fight like that.
This may seem like nitpicking, but if you want to discuss the politics of space, the distance between planets and the travel time between space polities becomes a critical aspect of politics.
The Expanse is in an uncanny valley of hard sci-fi. It's not as realistic as Kerbal Space Program but use technology as a magical way to explore speculative scenarios like Star Trek did.
And a core part of the first arc is a stealth ship which is not hard sci-fi at the Expanse's tech level: http://www.projectrho.com/public_html/rocket/spacewardetect....
You basically take straight line paths between to points in space, constantly accelerating for half the journey then flipping over at the half way point to decelerate for the rest.
Earth to Mars at closest takes 46 hours at 1G. Earth to Jupiter at closest takes less than 6 days. With 1G torch ships, the entire solar systems becomes accessible in less than two weeks journey. And the Expanse has ships that have much more acceleration.
Rockets exchange impulse with the exhaust at a linear rate (mv), but put the kinetic energy into it at a quadratic rate (mv²/2), so increasing mass efficiency by increasing exhaust speed / temperature costs more and more. Realistic with fusion reactors, to the extent to which compact fusion reactors themselves are realistic. Or even with fission reactors, in the form of bombs (see project Orion).
Nothing like the current simple, low-tech chemical rockets.
http://toughsf.blogspot.com/2019/10/the-expanses-epstein-dri...
The discussion at the bottom of the page has also a lot of interesting ideas.
Just crazy, I am stoked to see what new technologies and possibilities will arise in the next few decades.
That said, video calling was the realm of exclusive, high-tech / demos for a long time, then without really being aware of, it's been available in everyone's pocket for a long time now. It went from near-sci-fi to mainstream in the blink of an eye.
Besides that a robot limb can't be autonomous in it's movement as most movements we do are asymmetrical and thus it needs input from the other limb as well.
Some simple arguments that it's not a ridiculous question:
There is stealth on earth - paint and geometry that reduces EM signature. Why couldn't there be something similar in space?
It's not like it's super easy to detect everything in space today either - we have big telescopes but regularly miss small asteroids?
Some Sci-Fi has tried addressing it with plausible ideas - like for instance dumping all heat into shielded internal tanks, which have to eventually be vented(so that stealth cannot be infinite because you run out of heat storage capacity on board).
The James Webb space telescope cools it's observing side instruments to 10s of degrees above absolute zero, using active cooling. I wonder how hard it would be to detect from it's cool side, at a space combat distance?
Asteroids in the near solar system are normally 100-150 kelvin, apparently, and don't seem trivial to spot.
All that still seems to allow room for stealth in a hard sci-fi setting.
This and other points are discussed here: https://tvtropes.org/pmwiki/pmwiki.php/Analysis/StealthInSpa...
There are a number of methods one could theoretically use to minimize these factors. As an example, imagine the detectability of a small angle coherent neutron beam or the IR exhaust of a black hole starship.
Its still more fantasy than science, but hey, so are warp drive, hyperspace, and all that jazz :)
If heat signatures are a sure way to identify space ships, then the value of stealth comes in at the limit of detection range. If an enemy can only detect me at X units away, but I can detect him at X+1 units, I have an advantage.
If I'm spouting nonsense, I'd be legitimately delighted to hear why it can't work.
X+1 detection range isn't much of an advantage if X already includes most of the places you can actually be and/or X is already an order of magnitude past effective weapons range.
The rest of stealth in space is relying on the vastness of it. A spaceship a few kilometers away is already hard to see.
they do actually address this in the show. you can infer from the dialogue that they don't expect to be "invisible"; rather, they are trying to be indistinguishable from space junk.
I do think people are being a bit harsh in this thread. the show isn't perfect, but it's about as hard sci-fi as you can be while still getting renewed each season.
I noticed that, but it is obviously a necessity for the TV version so that the plotlines are not interrupted. I’ll allow it
The one thing that bugs me a bit is the way they conceptually represent the solar system in the show. If you follow the way the situation is represented you essentially have Earth on one side of the solar system, Mars in the middle and the asteroid field on the other side. That seems to be how the strategic situation is presented. To get from the asteroid field you essentially have to go past Mars, which is closer to the asteroids. If you think about the actual layout of the solar system this makes no sense, in reality Earth is about in the middle and any given asteroid is closer to the Earth at any given time than it is to half the rest of the belt.
Again, it's fine. There's no way to capture the real dynamics of the solar system in the story without hopelessly bogging everything down, and for the purposes of the show the simplified model works fine. I suppose you could argue that during the period of the show by chance most of the main asteroids and Mars happen to be lined up on roughly the same side of the solar system as Jupiter, and then it basically works. It's just a bit of a fudge.
This of course ignores that with the Epstein drive magic, one could always trade travel time for going around ie. off-plane. There's plenty of, well, space for that. (Edit: according to the no-stealth-in-space link in a sibling post, one would be seen doing that, and likely get chased for it as being suspicious).
But aside from that and the whole aliens technology thing the plot revolves around, it is very realistic. They certainly get a lot closer than anybody else.
Power = m v a = 1e9 x 1e5 x 1e1 = 1e15 W
While petawatt is a lot, a megaton ship is also huge. Epstein drive is a fusion drive of sort, the easiest aneutronic reaction would be
B+p -> C + 16 MeV
So 2.5e-12 Joules per fusion
Which means you need to burn
1e15 J/s /(2.5e-12 J/atom)*(2e-26 kg/atom) = 8 kg/s
Suppose your engine runs at 10% efficiency, it means you are powering a megaton ship on less than a 100kg/s of material. So if your megaton ship starts as 10% fuel you have ~115 days of continuous thrust.
But that gets to what the Epstein drive basically is, in-universe: a 100% efficient fusion drive. No physical laws being broken, technically, just the nuclear rocket equivalent of a perpetual motion machine.
They do in fact go around at 1G (or 1/3 G) thrust for months at a time in the books and show, accelerating full speed for half the trip, then turn around and decelerate for the other half, for trips to/from the outer solar system. In the inner solar system it's only a few days to weeks to get anywhere. This lets them operate in artificial gravity without spinning the spacecraft, which is convenient for filming (although it's in the source novels too).
EDIT: Well, I should say that the propellant mass/delta-v is really high and that most of the fusion energy will can end up as kinetic energy of the propellant and ship. But the vast majority of that kinetic energy will be the propellant rather than the ship. To maximize ship kinetic energy over fuel energy you want the propellant to exit the ship at the same velocity the ship is traveling which is very far from what you see in an Epstein drive. But fusion provides tons of energy so that isn't going to be a figure of merit we care about.
Re: accelerating for many months at 1G is definitely bad physics, not only are you relativistic, you start getting into the kind of speeds where a minor meteorites will wipeout your ship. 1 gram meteorite with a relative velocity of 0.5c has 1.4e13 J of kinetic energy = 3.5 kton of TNT, so a small nuke.
For me, good sci-fi does just that, ie limit the magic to one thing or technology, and use that to explore something interesting.
Same with Altered Carbon. What would happen to society if we could swap bodies but keep our minds? That one piece of technology ("the stack") is magic, but from it follows lots of interesting exploration of the possible impacts on society etc.
What I hate is when they try to explain the magic. Don't do that. It never works. Just assume it's there, someone discovered it, invented it whatever.
For example, it matters how is it the ships can casually sustain a 1G burn for a week at a time. If it's efficient nuclear fusion, then the ships get bulky, energy is no longer a problem in the society at large, and the exhaust of said engine is a weapon of mass destruction. If it's subspace field shenanigans, then aforementioned impacts don't necessarily apply, but there is an open question of how small such subspace field combobulators can get, and what else could you do with them.
Technologies have second-order consequences, and societies shape to accommodate them. Half the fun of science fiction is in exploring those.
If you just call it magic and define it by a set of arbitrary rules, then your fictional universe will look shallow and inconsistent.
You don't always have to. Vernor Vinge explains it as, you are allowed one central conceit which frees you to deeply explore some core theme. That single wild assumption has the interesting property of being both inconsequential to the themes you wish to explore and the single thing that makes it all work. A lot of good hard science fiction has this property: there is internal consistency and broad agreement with real world physics but with at most a single unexamined wild assumption from which the consistently handled deviations flow from. The Zones in his Zones of thought or the Bobbles in Across Real-time are examples of this principle applied for excellent effect. Orthogonal by Egan is an interesting one when viewed in this lens, what with it being physically unrealistic but mathematically driven.
A lot of would be hard scifi authors, in the hopes of increased realism, mistakenly add too much unnecessary detail to the detriment of their story or core big idea. On the other hand, if you manage your central conceit well, you might sometimes be able to enlist the imagination of your readers (some of whom will have more technical expertise in the relevant area) to fill in the blanks.
Star Trek goes into intricate detail trying to explain its warp drives and comes off looking far less grounded than the vast majority of sci-fi properties with FTL or jumpgates or whatnot that either don't explain anything, or just offer a few details. Whether it breaks your universe depends on the themes you're trying to explore, such as the nth order effects of radical technologies on society. Most of the time, the story isn't about the technology (in the same way that Westerns aren't always about animal husbandry and gun manufacturing), and it's sufficient that you push some buttons, pull a lever and spaceship go brrr.
As much as I love Star Trek, it isn't really explaining all that much (it would be, if the writers could be arsed to read the technical manuals created for the series, but even the manuals themselves say they aren't mandatory reading, so here we are). It's DDoSing your disbelief with technobabble to allow for whatever plot the episode's writer had in mind.
(Though it's not impossible to make something relatively consistent out of Star Trek's universe; /r/DaystromInstitute is a subreddit essentially dedicated to doing just that. It's an exercise in function interpolation, but having lots of data points does constrain possibilities.)
> Most of the time, the story isn't about the technology (in the same way that Westerns aren't always about animal husbandry and gun manufacturing), and it's sufficient that you push some buttons, pull a lever and spaceship go brrr.
There's very little point in choosing sci-fi as your setting if your story is setting-independent. The westerns whose story is entirely interchangeable with action movies set in ancient times or present days don't tend to be very interesting movies (YMMV). Or at least I tend to avoid those, because I find them boring. With sci-fi, if the story is all about setting-independent human drama, I can have that with any other genre. I like my sci-fi when it extrapolates and elaborates on science and technology, and its impact on societies.
That's it for me too, but what I'm trying to get at is that I vastly prefer it without "higgs reactor", "tachyon transmitters" or similar nonsense.
But don't try to explain the inner workings of the magic by spouting nonsense. That just takes me out of the story. Take it for granted, aliens made it, something other than semi-randomly assembled sentences sprinkled with fashionable pop-sci terms.
everyone is entitled to define their own categories, but to me a key element of sci-fi is that the science and its implications drive the story as much as the characters. if the science merely enables the story, it's space fantasy.
The science in that case is necessary to bring the plot elements together and constrain the action under a set of known rules and behaviors regarding hyperspace and related technology, but little of it is explored in detail. It's just there for the same reason that boats have to be there for a story set in the Age of Sail.
a common trope in sci-fi is that jumpgates (or something similar) were built by some ancient super-advanced civilization, while the current civilization understands them to the minimum extent necessary to actually use them. this is a good way to sidestep the issue, since any inconsistencies can plausibly be the result of missing knowledge in-universe.
as to "whether it's still sci-fi", imo it depends a bit more on the setting. if FTL has already existed for 100+ years, it makes sense for it to be a background detail. on the other hand, if you have a story where FTL was discovered recently and it doesn't profoundly impact the plot, I would consider that to be pretty bad sci-fi.
like I said, this is just how I personally categorize things. to me, sci-fi is not just lasers in space. it's a genre where science/technology drives the plot, rather than being made up after the fact to justify the plot you want to have. it can still be sci-fi if the tech is totally implausible from a modern physics perspective; it just needs to be consistent.
star wars is usually my go-to example of "not sci-fi". there are no consistent rules for how anything works in-universe. all the technology works in whatever way is necessary to justify the current scene and will likely contradict itself later for a different scene. it's still a very enjoyable franchise, just not what I would consider sci-fi. a show like the expanse is almost the opposite. there's some unrealistic stuff in there, but it's internally consistent. once you nail down what's possible given "the rules" in-universe, the plot almost writes itself.
For the record, Babylon 5 was explicitly designed to be The Lord of the Rings in space. It's fantasy in sci-fi dress-up. Similar things could be said for Star Trek, Star Wars, and other sci-fi staples.
Hard science fiction like The Expanse, or most of the collected works of Arthur C Clarke, Alistair Reynolds, Kim Stanley Robinson, and Robert Forward present entirely self-consistent universes set in the future with logical extrapolations of technical capability governed by physical law.
Some people don't care for the distinction, but there are also those of us that have very strong preferences for ONLY readying hard science fiction. I like to feel that I learned something, or that the book describes societies that might someday come into being, or alien cultures that might realistically exist.
You need magic to describe shit that doesn't exist. Otherwise, then nothing makes sense? How do you have FTL when any possible explanation of how it works might as well be words chosen at random from a textbook because none of it will be plausible.
> If you just call it magic and define it by a set of arbitrary rules, then your fictional universe will look shallow and inconsistent.
Literally doesn't make any sense. All your complaints are second order issues. Good Sci-Fi places rules around its magic and is consistent about it. What "good" sci fi that relies on tech that doesn't exist is there that DOESN'T have its magic bounded by in universe rules.
Sci-Fi breaks down when you start to ignore or make up new rules around the magic, especially if its just "stupid"
This applies to just about all fictional combat, no matter the setting.
Also, if you are looking for any kind of realism in Star Trek battles you are completely missing what the series is about.
I like SF and I love Star Trek just as I love reading hard science fiction. Just don't mistake the two, because looking for realism in Star Trek would be like trying to do linguistic analysis on magical incantations in fantasy.
It's a more realistic space game than Kerbal Space Program and focuses on orbital combat. It does have a steep learning curve since it is literally rocket science, but if you've played KSP or other games with realistic orbital mechanics, you'll be able to pick up the core aspects easily.
https://www.adastragames.com/attack-vector-tactical
They do some nifty things with letting you use kinetic to constrain the maneuver of your opponent so you can better employ your lasers, etc.
It provides a good intro on how to deal with 3D vectors in a 2D boardgame
At first I thought the original post was about the first video game ever made, Spacewar!!
Play Spacewar! online: https://www.masswerk.at/spacewar/
A recent stream: https://www.youtube.com/watch?v=dD6cyXdXyzs
Custom designs are insanely more powerful than the builtin ones. Either design a fission plant with super high temp cooler side (to keep your radiators small) and then go full laser star or make sandblaster railguns. 1g nuggets of stuff blasted as fast as possible with ridiculous rate of fire simply ablate through any armor anyone can design.
Or just design a gun that shoots guns that shoots guns that shoots guns that shoot nukes.
The time when they didn't consider the pressure of tritium inside a nuke was hilarious. One could design a basic implosion nuke -> fill it with absolutely insane amount of tritium and make a few tens of kilos weighing 10 gigaton nuke or whatnot. And then just watch the fireworks.
I really love that game. The shenanigans one can pull off.
In an alternate reality, mastery of Kerbal Space Program becomes a political qualification.
Any thoughts?
So could all of the military if you want to go down that path. There is nothing special that makes something “military only”. Cops are civilians as are secret service and members of the CIA and they kill people on and off US soil.