I am looking at different ways to destroy a planet - because a society within my setting wants to destroy a planet. I am assuming the planet is of a similar size and composition to the Earth just to keep things simple.
I am starting at boiling the atmosphere to the point where it turns Earth into a dead barren rock with no vegetation, no oceans and no air left. This is as tame as I want my destruction (there's still a giant dead rock left, and I want to wreak more havoc than this!).
I am also looking into lasers powerful enough to obliterate a planet into dust, AKA the Death Star approach. At the most I am not sure if the energy required to achieve this makes this a feasible option. (Yeah, I know, I am concerned if this is feasible and then I go onto consider something else like:)
Ive been considering something that destabilizes the very structure of a planet, affecting everything from plate tectonics to the planets own gravitational pull on itself and causing a chain reaction which results in the planet flying apart. But I am not sure if I can back this up with any kind of science.
I have also considered launching another, large enough, rock in space at a planet to smash it into smithereens. I have also looked into detonating the nearby star to take out the planet and the entire system.
My problem is that I don't know which one of these (or any other crazy ideas that I have) forms of global destruction are the easiest to achieve. So my question is:
What would be the most effective or efficient way to destroy an entire planet?
I dont just want to destroy all life on the surface, I want to reduce the entire planet to rubble so that very little remains (I guess an asteroid field/belt being left behind is destruction enough, but bonus points if you can cause more destruction!).
I also want to do this in a relatively short time frame. Say, less than a day.
I plan to model my fictional society on the answers given here.