But you can't create artificial mass to accelerate anything... and protect your ship from it... We do not have Element Zero from Mass Effect to do so. Therefore a grav driver won't work. A gauss canon can achieve higher speed if the gun laying drive is large enough, which of course it isnt... in contrast to a transrapid train you are not on a rail from start to hit. And the realoding speed is bad as the magnetic field needs to be turned back AND needs to be outside the influence area of the first projectile. In contrast a railgun has a constant magnetic charge field, only waiting on a electrified bullet, sliding into the drive to get propelled. That thing can shot dozens a second.
As far as I know though, there are three ways of composing space weapons that work.
1) A energy wave weapon
2) A heat weapon
3) A high density projectile
Furthermore on the ground:
4) Shock weapons
Everything got a counter... apart of the first one and the last. The former got shields in DW.
1) A energy wave composed weapon creates a high and short radiation in a specific angle and thus doesn't damage the weapon itself by avaoiding contact alltogether or is a self synchronizing beam in a semipenetrateable mirror system (see laser basics) like our beam here and creates a constant stream of energy. Getting your high energy projectile radiation to stop without doing damage is impossible. Dispersing inside of energy fields seems practical, though energy consuming and hard. Armor will not survive that!
2) A heat weapon is composed of a matter cluster, heated to an extent, that it nearly vaporizes itself. This condition is called plasma as we know it. Getting in touch with it without a good "cooling" system - in this case a cryoreactive armor - would be pretty bad. The heat needs to be dispersed and absorped to avoid high temperature fluctuation. Therefore a cryoreactive armor would be something that is considered a quick conduit for temperatures, never allowing a high peak of self destructious heat. Apart of the damage it does to systems and armor it got a energy field in itself and is therefore victim to energy shields. Thus apart of the matter component involved it still gets diminished by anti-heat shields and energy shields alike, making it an allround weapon without benefit anywhere.
As ion weapons are energy absorbed matter particles they count to this hybrid class too, but dont interact with armor only shields.
3) A matter projectile, composed of metall to get charged by electricity like a railgun or a bigger version, is a good idea to penetrate armor, if designed to break it. Though the metall component allows for a slow diminish by electrical current shields, the high velocity of a small projectile, which time in the field of the energy shield is short, will not decrease tremendously and as such is nearly immune to shields. Since high density is a main factor for physical pen-shots using non metalls is out of the question. Therefore a little immunity by shields will always be granted never mind the technology you use. A metall slug in a grav driver would still be able to get influenced.
4) There are many more deadly weapons which can not be used in space. For once there would be a shock wave cannon. As all ships in space are composed of matter a landing troop ship should be able to be bombarded by high frequence shock wave cannons to destroy the ship. For example the planetary defense got a triangulated shock wave cannon system. They cross their shots as to not disrupt the enemy pushing them away in a wave, but utterly crush it inside all waves in all directions at once. Even high air pressure is deadly. Pressure weapons in water are simply genocide. Ask the fish after you bomb a lake. Now image droping a 'Zar' nuclear bomb 3km deep in the sea. You will find no live even 10 km outside the blast radius, all crushed by the shockwave of compressing water.
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