SWM wrote:Starting from the target ship there is: (1) Ship's Armor (thousands of years in the future they have to have stronger materials than now, Some kind of energy distribution layer, maybe a reflective coating to diffract the lasers), (2) Gravity side-walls (how much of the energy do they block?), (3) Space between missile and ship (I know it's not much, but the beams have to loose some energy along the way), (4) Time (the missiles destroy themselves in the attack and the target ship is moving, so how long do the lasers make contact?), (5) Movement (the missile and ship are moving in relation to each other; the easiest defense for the ship would be to move in order to diffuse the effects of the laser across a larger surface area), (6) Each missile has multiple laser-heads, so how much energy does each get?
In response to some of your specific questions:
(1) is answered in In Fire Forged.
(2) also answered in In Fire Forge.
(3) the beams don't lose energy, they just spread out a bit. But since they are x-ray lasers, they don't spread out all that much from the warhead to the target.
(4) and (5) the beam itself only lasts a tiny fraction of a second. The ship doesn't move very much in that time.
(6) the laserheads don't share the energy between them. Each laserhead can only utilize the energy that impacts that specific laserhead. Since the laserheads don't block each other from the energy of the nuclear bomb, it doesn't matter to the laserhead how many other laserheads are nearby. Each laserhead will get as much energy as it gets from the nuclear explosion. Suppose you design a missile with a single laserhead, which generates 1 GJ of energy. If you now use the same warhead with six laserheads, each laserhead will generate 1 GJ of energy (assuming you design it such that no laserhead obstructs another). Any energy from the bomb which is not intercepted by a laserhead is essentially wasted (as far as generating x-ray lasers).
In the end, though, you are correct that the necessary energy is huge. IFF states that it could be in the terajoule or petajoule range.