How the quantum vacuum perturbs atoms, could shrink black holes and may have helped form galaxies

The word "vacuum" may conjure the image of empty space. Maybe you think of a region far outside the solar system without planets, debris, gas clouds or light. According to quantum theory, however, a vacuum is never truly empty. Quantum mechanics extends the Heisenberg uncertainty principle, which states that we cannot measure the position and the velocity of an object exactly at the same time, to a vacuum. The result is that a vacuum can never be still.