There is one other small point to make, it occurs to me, regarding lasers and appropriate uses of same.
One of which is that the Imperial Navy, by and large, uses carefully targeted laser weapons for short-range point defense, the intent being to vaporize small projectiles, blind sensors, overheat close-in AKVs and send ’em into thermal shutdown (being small, they have precious little heat-dumping capacity, relying instead on avoiding being hit), and convince missile warheads (for those people who feel the need to use missile warheads, kinetic energy being plenty of fun on its own) to explode before they actually get to their target starship.
Some folks (the screenshot on the right is from Battlestar Galactica) are of the opinion that an even better way to do this would be good old-fashioned flak. Mount point-defense turrets on your ship, and fill space around you with enough projectiles that anything incoming gets shredded by those before reaching you.
What those folks forget is that Sir Isaac Newton is the deadliest son-of-a-bitch in space!, ’cause all those projectiles – all those clouds of projectiles – will keep moving, with all their kinetic energy, until they hit something, and ruin its day. If you’re lucky, that will be whatever poor bastard is next to you in the same formation, weapons and small craft you’re trying to use, or your own ship on some future occasion, and you’ll only manage to hurt yourself. If you’re unlucky, they’ll just carry merrily on hitting things completely unrelated to the original target at random and providing people with casus belli, atrocity fodder, and other reasons to whup your ass for the next ten thousand years or more.
Cleaning up the debris after a space battle to ensure this sort of thing doesn’t happen is already a giant pain in the ass (the kind that there’s even a dedicated class of fluffship – crewing which is generally thought to be the worst job in the IN – to handle) when all you have to worry about is hulks, spallation debris, ricochets and accidental misses, and such-like, without deliberately making the problem a million times worse by filling the sky with high-KE flak. You don’t fire anything without a firing solution attached to it. Here endeth the lesson.
Or, as Mass Effect 2 put it in a somewhat more pithy manner:
a pointy missile (it helps) with a high temp resistant ceramic coating (really helps) and a heat transfering layer underneath (going into that thermal goop stuff) can eat quite a lot of heat to the point that a beam laser would need tens of megawatts per a square meter to ablate armour. pulse lasers can be defeated by having the armour be layered and subdivided localizing damage into one tile which can then be rotated off the threat axis. all of which is defeated by a gram sized lump of steel driving through the armour at 50km/s+relative velocity. also if your vector control tech can be used at any range at all you could activly guide single railgun bolts to a hit