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.

Instead of an empty space, we can imagine the vacuum as a dynamic object, with regular fluctuations in energy.

Physicists at the University of Cambridge in the United Kingdom recently presented preliminary research showing direct imaging of these fluctuations in a lab-made quantum vacuum. Physicists have “seen” the quantum vacuum many times before, however. And we can all see the effects of the quantum vacuum on atoms in the atmosphere—through the gorgeous light displays of the aurora borealis.