At the beginning of the 20th century, Einstein changed the way we think about time. Now, early in the 21st century, the measurement of time is being revolutionized by the ability to cool a gas of atoms to temperatures millions of times lower than any naturally occurring temperature in the universe. Nobel Prize recipient William Phillips, Ph.D., a Distinguished University and College Park Professor of Physics at the University of Maryland, talks about laser cooling and ultracold atoms and how they relate to time.

Atomic clocks, the best timekeepers ever made, are one of the scientific and technological wonders of modern life. Such super-accurate clocks are essential to industry, commerce, and science; they are the heart of the Global Positioning System (GPS), which guides cars, airplanes, and hikers to their destinations. Today, the best primary atomic clocks use ultracold atoms. Series: "UC Berkeley Graduate Lectures" [Science] [Show ID: 37727]