What is impenetrability?

Answer 1

It is literally the inability to be penetrated (pierced, soaked through), to a greater or lesser extent. Nothing is completely impenetrable.

It is used metaphorically to indicate something not understandable, or incomprehensible -- not because it does not make sense but because it is presented or explained in an unenlightening, obtuse, or unclear manner (to use another idiom, it is "too dense").

Example: Quantum mechanics textbooks are renowned for their impenetrability.

Answer 2

Impenetrability refers to the property of being impossible to pass through or penetrate. It describes the inability of a substance or object to be crossed or breached by other substances or objects.

Answer 3

"No two things can occupy the same space, at the same time."

Answer 4

The law of impenetrability is that "no two things can occupy the same space at the same time." It is a statement made about logical space.