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 ...

Hang two pendulum clocks on the same wall, and over time, something strange will happen: the two clocks will tick in synchrony. Renowned Dutch scientist Christiaan Huygens, the inventor of the ...

What a makes a good clock? Andrew Ludlow, a physicist at the National Institute of Standards and Technology, says one of the most important criteria is stability. "If you could imagine a grandfather ...

Here’s how to build a pendulum-controlled clock which can be made really accurate. Retro? – yes, but an interesting project all the same. You’ll need a spare quartz clock which must be adapted by ...

John Harrison, one of the world’s greatest clockmakers, claimed to have designed the perfect pendulum clock in the mid-18th century. Instead of being celebrated, Harrison’s plans were chastised and ...

Would you believe a pendulum clock that can keep time accurately to within one second per year? If you answered “yes”, you’ve either never tried to regulate a pendulum clock yourself, or you already ...

Two-quantum oscillations of atoms in a semiconductor crystal are excited by ultrashort terahertz pulses. The terahertz waves radiated from the moving atoms are analyzed by a novel time-resolving ...