How do I prevent rigid body objects from falling down before they are hit? I have done BlenderGuru's Quick Rigid Body Fun on Rigid Body Collisions. 



Regarding this .blend file:



When you play the animation, the cubes start falling down long before they are hit by the wrecking ball. This is because of gravity and because there is some space between the cubes. How can you prevent the cubes falling down or at least arrange that the cubes don't fall down before they are hit by the wrecking ball?

P.S Blender Guru says it is necessary to have some space between the cubes because if there is no space the wall will explode. I have here another .blend file...



...where there is no space between the cubes, so I don't think he is right. But the stones don't behave like there is a wall .... hmmmm ???
The simplest answer to this is to apply transforms to all of the cubes. Ctrl+A>Scale and then in the physics panel, enable deactivation and start deactivated for all cubes so that the simulation does not take over the objects until they interact. Just enable the option for one, then choose copy from active in the Tool shelf with all cubes selected.