Time

The question of why time moves forwards, and not backwards, has long been on the minds of physicists. Now, a professor at UC Berkeley has a new theory: as the universe expands, it drives the expansion of time, which creates a constant series of new “now” moments.

Shadowplay is a clock which needs to be touched before it will reveal the time. It does so by casting shadows for the hour and minute hands.

If you want to know what time it is, you’ll have to do a little work with this clock. Meet Albert, a wall clock for children that breaks down the current time in math problems. Named after Albert Einstein, the clock makes you solve math problems in order to tell the time.

If you don't feel comfortable unless your watch is showing the exact time, then mark June 30 on your calendar. On that Tuesday at precisely 23:59:59 GMT, the world's clocks will add a second to that day, making it 24 hours and one second long.

A smartphone app or an internet search are effective enough ways of working out the time in other locations, but perhaps aren't quite as elegant as the World Clock. This stylish timepiece can quickly show you the time in 24 different time zones, needing only a little push in the right direction.

The Ora Unico may be just another analog watch, but with a unique face which hides the time inside a doodle, it's likely to turn heads. A white squiggle reveals all, with one end pointing to the hour, the other pointing to the minute.

The watch manufacturer Rolex has developed a pair of bespoke analog instruments as backups for the Bloodhound SSC, the jet-powered car being built for an attempt to set a new world land speed record of 1,000 mph (1609 km/h).

The Cesium 133 from Bathys Hawaii is the world's first true atomic wristwatch. Boasting an internal cesium atomic clock that's claimed to be accurate to one second over 1,000 years, the Cesium 133 is a rather expensive but utterly unique timepiece.

The US Department of Commerce's National Institute of Standards and Technology (NIST) has announced the launch of a new atomic clock as the official standard for civilian time. Called NIST-F2, it is so accurate that it will lose only one second in 300 million years.

The Christophe Claret Maestoso showcased at Baselworld 2014 uses a detent escapement – a movement of remarkable accuracy that’s almost impossible to install in a watch.

Nadir is a watch with hands that point inwards rather than outwards. This changes the aesthetic, offering an unusual perspective on time. With your eye drawn naturally to the center of the face, Nadir arguably makes it easier to tell what time it is.

Durr is a watch like no other: it has no face with which to tell the time, instead vibrating every five minutes to reveal the passing of time in another, more unusual way.