Humanity has used clocks since we became aware of the concept of time. And as technology has improved, so have our time-keeping methods. Today, many people rely on digital clocks to track the hours ...

Ultrafast lasers emit pulses lasting only a few hundred femtoseconds (quadrillionths of a second). These flashes of light power applications from precision micromachining to eye surgery to optical ...

You can buy all kinds of conventional clocks that have hands and numbers for easy reading. Or, like [Fabio Ricci], you could build yourself something a little more esoteric, like this neat shadow ...