Keeping track of time seems simple. A watch ticks, a pendulum swings, and a calendar flips. But at the quantum level, marking time is far more complicated — and far more expensive than anyone expected ...

When you think of making something using a lathe, you usually think of turning a screw, a table leg, or a toothpick. [Uri Tuchman] had a different idea. He wanted to make a clock out of the gears used ...

Biological timekeeping : the body's rhythms -- Calendar : different drummers -- Early clocks : home-made beats -- The pendulum clock : the beat of nature -- Successors : ubiquitous timekeeping -- ...