We live in a cold and empty universe, in a time when energies are so low that we can no longer see what space contained in the fiery instants when the universe was born. But every kind of particle that ever existed is still there, in the equations that describe the particles and forces of the universe. And we can use accelerators to make the equations come alive: not just as metaphor but as reality.

The universe today contains only the stable relics and leftovers of the big bang. The unstable particles have decayed away with time, and the perfect symmetries have been broken as the universe has cooled. But the structure of space “remembers” all the particles and forces we can no longer see around us. Particle accelerators pump energy into empty space to create the particles and uncover the symmetries that existed in the earliest universe. As accelerators go to higher energies, we probe ever closer to the beginning.

Ultimately we must combine what we learn from accelerators with what we learn by detecting the surviving relics of the big bang, using telescopes on the ground and in the sky. It is by synthesizing what we learn from each of these approaches that we will make the two ends meet and develop a comprehensive picture of the universe and how it evolved.