This program narrated by Jane Curtin explores planetary orbits, circadian rhythms, time dilation, intergalactic wormholes, and other phenomena to quantify the common denominator of all that exists: time. Experts from Harvard, Columbia, and Tulane Universities; the Center for Biological Timing; and the U.S. Naval Observatory discuss timekeeping innovations, including the pendulum, marine chronometer, atomic clock, and Global Positioning System, and applications of time-related scientific and technologic advances to areas such as navigation, genetics, and space exploration. A Discovery Channel Production. (53 minutes)