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 assistant 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.
“A rock is a clock, so to speak,” Müller said.
In a paper appearing in the Jan. 11 issue of Science, Müller
and his UC Berkeley colleagues describe how to tell time using only the
matter wave of a cesium atom. He refers to his method as a Compton clock
because it is based on the so-called Compton frequency of a matter
“When I was very young and reading science books, I always wondered
why there was so little explanation of what time is,” said Müller, who
is also a guest scientist at Lawrence Berkeley National Laboratory.
“Since then, I’ve often asked myself, ‘What is the simplest thing that
can measure time, the simplest system that feels the passage of time?’
Now we have an upper limit: one single massive particle is enough.”
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