"We have interplanetary travel but we fight with swords"

[Stahlseele]

Well, not without completely sealed power armour at least.
Basically, what our Astronauts use today coudpled with an armored Exo-Skeleton.
JIM Suits ( http://en.wikipedia.org/wiki/JIM_suit ) adapted for Space-Use?
See Spess Mehreen Powa Armour.
Or Battletech Clan Elemental Suit.

[Laertes]

Well, not without completely sealed power armour at least.
Basically, what our Astronauts use today coudpled with an armored Exo-Skeleton.
JYM Suits adapted for Space-Use?
See Spess Mehreen Powa Armour.
Or Battletech Clan Elemental Suit.

It's the economics of it, coupled with how easy detection is in space. You'll see people coming from weeks away, and battle-capable spacecraft are so expensive to build in orbit (even if you have a space elevator) that nothing even vaguely George Lucas is going to result.

[Stahlseele]

Which is why you would probably not have battle ready space ship, but power armor instead right?
Smaller, cheaper, lighter, easier to get into space in the first place, easier and cheaper to manufacture in space too, because you need less ressources to do so compared to building larger things correct? O.o

So either you need to have these on board of unarmed ships to try and resist boarding actions or you need to establish that ships are not to be attacked in something like the ares conventions.

[Laertes]

Smaller, cheaper, lighter, easier to get into space in the first place, easier and cheaper to manufacture in space too, because you need less ressources to do so compared to building larger things correct? O.o

It's a per-kilogram thing, so bringing a hundred small things up is the same cost as bring one large thing up.

So either you need to have these on board of unarmed ships to try and resist boarding actions or you need to establish that ships are not to be attacked in something like the ares conventions.

The issue is that there will be no boarding actions, because shooting down a spacecraft is trivially easy. You can see a spacecraft coming from a very long way away, because a spacecraft is a warm body that's constantly sending out EM signals and it's against a very dark background indeed. To shoot it down all you'd need to do is plot its approximate course, and then accelerate some very small things towards it very quickly. Those very small things would be difficult to spot because once they're done accelerating they're cold matter, with no engines or anything. Therefore defensive maneuvers would be basically impossible until it's too late.

For reference, this is a picture of a hole made by a fleck of paint travelling at orbital speeds:

It would not be difficult to build a space weapon which fired a hundred ball bearings at ten times the speed of that. A space suit which can stand up to that sort of firepower isn't a space suit, it's an armoured spacecraft in its own right.

Or as you say, you could have a world in which there's an agreement that everybody follows whereby they restrict themselves to a very inefficient form of combat. That stretches my suspension of disbelief, but it may be fine for yours.

[deaddmwalking]

In Sci-fi, dealing with high speed dust is something they have to be able to handle. In Ender's Game , the propulsion system converts matter they encounter into propulsion energy (also weaponized to destroy planets).

There are lots of possibilities.

[OgreBattle]

Well, not without completely sealed power armour at least.
Basically, what our Astronauts use today coudpled with an armored Exo-Skeleton.
JIM Suits ( http://en.wikipedia.org/wiki/JIM_suit ) adapted for Space-Use?
See Spess Mehreen Powa Armour.
Or Battletech Clan Elemental Suit.

Check out the AX-3 Hardsuit developed by NASA in the 70's
http://www.getaddictedto.com/hardsuit-s ... jSoAA.dpbs

[TheNotoriousAMP]

Another thing to remember is that Sci Fi warfare is fought under different numbers and density of forces. For example, take WW2. At its peak, you probably had a combined total of close to 70-80 million men under arms. Of these the Eastern front probably had 15 million crammed into it. Even in mass settings like 40k, you rarely have a situation with even close to those numbers involved. Sci fi empires have a much lower density of population than our planet, and logistics are a lot tougher. So in effect, 40k warfare, and Sci Fi warfare in general is a lot closer to a modernized version of the Napoleonic wars. Massive armies, massive campaigns, small frontlines.

Even Vraks, for example, which was one of the larger campaigns in numbers GW wrote about, was fought over a comparatively small amount of land. Seizing a planet involves only a few key areas, after which the opposition is no longer able to fight, which means that decisive clashes are much more important. How does this play into melee combat?

To break an enemy force and take land, you need to move the enemy off of it. Firefights are horrifically inefficient in this. 1- slugging matches are more costly and 2- once troops stop moving and start shooting, its really hard to get them back up again. Thus, melee combat, quick, decisive and psychologically "locked in" (need to take point, need to keep moving) makes a lot of sense for a 40k general. They consume fewer munitions, which need to be transported from abroad, relies less on attrition, which both sides can pretty much keep going, ad infinitum and their decisive nature ensures the seizing of key locations, which is what the campaign is about.

Plus, the Imperium actually can less afford attrition warfare than its enemies. Its like Prussia in the 1700's, they are surrounded by people who hate them. The Imperium needs to rapidly isolate opposing forces and eliminate them as fast as possible, to free up its troops for somewhere else. That, or if they do want to engage in attrition, they need to prevent the enemy from landing more troops or escaping and engaging them elsewhere. They are in a continual state of active defense, like Germany post Kursk in 1943.

In short, decisive shock action, especially with the increase in armor technology the 40k universe has experienced, fits perfectly the needs of its Faction's militaries.

[Ghremdal]

40 K is a bit specific in that regard. In general, the Imperium wants planets. Planet busting weapons are more of a last resort thing.

Anything less then a planetbuster won't kill off any opposing race, except maybe Exodite Eldar. The other races don0t really care about things like supply chain, creature comforts, etc.


Anyway, a link for those that want to learn more about hard SF, and why interstellar warfare is probably going to be a rare event, if at all.
http://www.projectrho.com/public_html/rocket/

[Stahlseele]

with hard sci-fi, interstellar war should become more of a cold war affair.
"we won't launch any big meteroites on collision course and relativistic speeds at your planet if you don't do that to us either"

[angelfromanotherpin]

I guess it depends how hard you consider the Alcubierre drive, which seems to just convert incoming matter into hideous potential firepower.

[Stahlseele]

Never heard of that.
Is that offence or defence?
If it's offence then that's what is known as a mass-driver.
You find a suitably large mass, attach some energy to it in a direction you want and smash whatever you hit on the way.

If that reverses stuff like that, i have no idea how the hell that's supposed to be hard sci-fi. hard sci-fi usually does not attempt to break the laws of physics.

[Previn]

I guess it depends how hard you consider the Alcubierre drive, which seems to just convert incoming matter into hideous potential firepower.

That's not how/what an Alcubierre drive does? Are you referencing the shielding used on the Alcubierre drive equipped ships in The Gripping Hand by Niven?

[Lokathor]

In the real life version of an Alcubierre Drive, any particles that get picked up by the Alcubierre Field during operation would get released as high energy radiation all at once when you decide to stop.

So, you could potentially weaponize that somehow, as part of a torpedo or whatever. Of course, anything you'd want to destroy by stopping a torpedo in front of it to blast with radiation would probably also be drastically harmed by having the torpedo simply attempt to Alcubierre Warp straight through it. You get superluminal torpedos of massive destructive powers.

[Previn]

In the real life version of an Alcubierre Drive, any particles that get picked up by the Alcubierre Field during operation would get released as high energy radiation all at once when you decide to stop.

So, you could potentially weaponize that somehow, as part of a torpedo or whatever. Of course, anything you'd want to destroy by stopping a torpedo in front of it to blast with radiation would probably also be drastically harmed by having the torpedo simply attempt to Alcubierre Warp straight through it. You get superluminal torpedos of massive destructive powers.

That's a theoretical from 1 paper, which uses some guesses as to what will happen when particles interact with the warp bubble created by the Alcubierre's drive, and has to modify the assumptions of how the drive interacts with space time. It's also not all particles, only some of them, and the reason they get would supposedly get released as ultra high energy is due to time dilation on the particles, which is also part of the modifications they made to the model.

I'm not saying it's wrong, but it's a big leap and a huge 'maybe it will work this way.'