Mathematics
The Divergence Theorem and Its Physical Meaning
Quick fact
The divergence theorem is also called Gauss's theorem or Ostrogradsky's theorem, and it is a special case of the generalized Stokes' theorem.
Why this is interesting
Imagine you are standing inside a room and you can feel air rushing out of every crack. How can you tell if there is a hidden source of air inside the room? The divergence theorem gives you the answer.