Pararaptor said:
The giant laser death cannon I brought with me in the time machine.
Lasers are overrated, not enough penetration, and they get reflected from targets by mirrors and even stopped by mist... MIST for gawd sake!
Newton's Laws of Impact Depth [http://en.wikipedia.org/wiki/Impact_depth] are universal, kinetic energy weapons have done us good so far as you pretty much NEED a projectile that weighs the same as the amount of material you need to displace. For example a bullet can only penetrate as deep through a human as the length of the bullet times the difference in density between.
E.g. a 1 inch long bullet will NEVER penetrate all the way through a 2 inch steel plate.
And the problem with a laser powerful enough to flash-incinerate the target (and create a destructive shock wave) is the atmosphere which interacts with a high energy laser beam making the range so incredibly short you might as well just use a gun.
Lasers are useful in space as weapons, but otherwise, they are only good for sensing like range finding, laser designating, etc.
I think any future of ranged weapons will be basically mini-Stinger missiles, auto-homing, extremely fast and burrows through thick body armour to detonate inside the centre of the target for massive damage (against the giant enemy crab, lol).