Ever since he was a kid growing up in Germany, Holger Müller has been asking himself a fundamental question: What is time?
That question has now led Müller, today an associate professor of physics at the University of California, Berkeley, to a fundamentally new way of measuring time.
Taking advantage of the fact that, in nature, matter can be both a particle and a wave, he has discovered a way to tell time by counting the oscillations of a matter wave. A matter wave's frequency is 10 billion times higher than that of visible light.