If you drop a buttered piece of bread, it will fall on the floor butter-side down (Murphy’s Law). If a cat is dropped from a window, or other high and towering place, it will land on its feet.
But what happens if you attach a buttered piece of bread, butter-side up, to the cat’s back and toss the composite out of the window? Will the cat land on its feet, or will the butter splat on the ground?
This answer is fairly easy to deduce, without even carrying out the experiment. The laws of butterology demand that the butter must hit the ground, and equally strict laws of feline aerodynamics demand that the cat cannot smash its back. If the combined construct were to land, nature would have no way to resolve this paradox. Therefore, it simply doesn’t fall.
This is the secret of antigravity. A buttered cat will, when released, quickly move to a height where the forces of cat-twisting and butter repulsion are in equilibrium. This point can be modified by scraping off some of the butter, providing lift, or removing some of the cat’s limbs, allowing descent.
Most of the civilized species of the Universe already use this principle to drive their ships while within a planetary system. The loud humming heard by most sighters of UFOs is, in fact, the purring of several hundred tabbies.
The one obvious danger is, of course, if the cats manage to eat the bread off their backs, they will immediately plummet. Of course, the cats will land on their feet, but this usually doesn’t do them much good since right after they make their graceful landing several tons of red-hot starship and pissed- off aliens crash on top of them.