Quantum physics has revealed a stunning truth about “nothing”: even the emptiest vacuum is filled with elementary particles, continually created and destroyed. Particles appear and disappear, flying apart and coming together, in an intricate quantum dance. This far-reaching consequence of quantum mechanics has withstood the most rigorous experimental scrutiny. In fact, these continual fluctuations are at the heart of our quantum understanding of nature.

The dance of quantum particles has special significance today because it contributes to the dark energy that is driving the universe apart. But there’s a problem: the vacuum has too much energy. A naive theoretical estimate gives an amount about 10¹²⁰ times too large to fit cosmological observations. The only known way to reduce the energy is to cancel contributions of different particle species against each other, possibly with a new symmetry called supersymmetry. With supersymmetry the result is 10⁶⁰ times better—a huge improvement, but not enough. Even with supersymmetry, what accounts for the other 60 orders of magnitude is still a mystery.

Physics theory predicts that one of the most important particles in the quantum vacuum is the Higgs particle. The Higgs pervades the vacuum, slowing the motion of particles, giving them mass, and preventing atoms from disintegrating. Since it fills the vacuum, the Higgs itself contributes to the embarrassing factor of 10¹²⁰.

The next accelerators are opening a window on the pivotal role of symmetry in fundamental physics. New discoveries will teach us about the role of the Higgs particle and supersymmetry in defining the vacuum. Such discoveries are key to understanding what tames the quantum vacuum, a topic that is fundamental to any real understanding of the mysterious dark energy that determines the destiny of our cosmos.