Hello everyone! I used to post here a long time ago, but now I'm back. Anyhooooo, I've started working on this science-fiction story, and it happens to involve 'realistic' space warfare. That sort of set me started on wondering exactly what a realistic space warship would be like. Of course, it's improbable that there would be actual space warfare in the first place - in the context of our civilisation for the next few hundred years to come - because it takes tremendous amounts of resources and energy just to build spaceships that aren't supposed to go and blow each other up. But let us suspend disbelief for a little while and imagine, purely hypothetically, what a space warship that is feasible given modern scientific knowledge and technology, might be like. Keep in mind that I'm just an amateur - I probably know a lot less about space physics than most people on these forums, so if there's something wrong with my reasoning, by all means, step in and correct me.
First of all, I believe that it wouldn't look anything like Homeworld. Homeworld looks cool, but it's not realistic. My first conception of 'realistic' space warfare is a little similar to submarine warfare in that 1) being in a small, confined space in a dangerous environment, if you get hit by the enemy (or vice-versa), it's likely to do a lot of damage very quickly, 2) you and the enemy are both difficult to detect, and 3) your vehicle is tremendously expensive to build and operate.
Given that context, let's examine the kind of environment we're working with. Unlike submarine warfare, where you can do a lot of things to evade things once detected, if your enemy in space can lock onto you with their telescopes, they can pretty much track you around forever. This would mean that stealth - not being detected in the first place - would be more important than ever. Space warships would accelerate to a certain speed, shut off their engines and then try to continue to cruise at that speed for as long as possible. If you're not giving off a lot of radiation from your engines, then it's rather difficult to pinpoint where your spaceship is, because there's such a vast field of vision in which to look, and your spaceship itself is comparatively tiny - like looking for a needle in a haystack the size of a football stadium.
To detect people actively, you'd need to be sending radar signals all over the place and seeing which signals are relatively more doppler-shifted than others, which might indicate a space vessel moving somewhere. However, since you're effectively broadcasting your location by sending these signals out, once you do find your enemy, they will probably know where you are as well. In this respect, it should also be similar to submarines, with their active sonar. So in this case, there would be a lot of emphasis on passive detection techniques - telescopes and radios and the like.
As for weaponry, since spacecraft are pretty fragile things, shooting missiles and such would probably do a lot of damage. A disadvantage of missiles would be that they are easily detectable - in the way that they spew out all that hot gas and radiation from their ends. A stealthier solution would be to fire mass-based projectiles at high velocity - railguns basically. Effectively, they'd simply be artificial micrometeorites. In a frictionless, airless environment, a fast-moving projectile - even a small one - would have enough kinetic energy to punch holes in large objects. They would also be difficult to detect. Lasers, on the other hand, are comparatively energy-costly - especially if you want to burn a hole through an enemy spaceship's hull, which would be armour-plated, or mirrored, to guard against possible laser-attacks. I'd imagine that lasers would be used a lot like the Taiidan defence fighters - to destroy incoming projectiles like bullets or missiles. It could be that this technology might be adapted from technologies used to destroy micrometeorites before impact. Nuclear missiles, which have a very high energy yield given a relatively compact size, might be useful in space, but their most damaging effects on earth - the concussion wave and the EMP effects - would not be so relevant in space, thus: 1) most of the damage would be done by the tremendous release of energy at once and 2) the EMP effects would be shielded against if the missile detonated at a large enough distance such that it could be dissipated by the ships' artificial magnetic fields - "storm cellars" used to shield against cosmic radiation and solar wind, similar to the Earth's magnetosphere.
Because of the very long distances involved in space combat, you might engage your targets from hundreds of thousands of kilometres away by firing your rockets, having the rockets accelerate for a while, shut off as they cruise in towards their targets, and then accelerate again as they zoom in for the kill. Or you might fire your guns many thousands of kilometres ahead of your target's possible trajectory and wait hours - or even days - for them to hit. To ensure a faster, more likely kill, then, you might want to move in closer to your target - but that would make it more risky for you as well.
Any other thoughts? Feel free to elaborate/criticize my ideas.