





Time is money – and never was this clearer than at 09:59:59.985 Eastern Time, on 3 June 2013. Due to a glitch in its time-keeping, the news agency Reuters accidentally released trading data just 15 milliseconds early. The result was $28m of transactions, as robot traders started dealing before others could get a look in.

Technology has now reached a stage where even the tiniest discrepancies can be of huge cost, pushing us towards a new era of time-keeping. The most accurate clocks can tick for more than 300 million years without losing a beat – and that is by no means the limit. Those time lords can influence everything from the financial markets to your car’s GPS. They may even allow us to test the substance of the universe itself.

Improvements in time-keeping have always been central to society's progress, since we stopped measuring its passage with the movement of the sun. The invention of the mechanical clock revolutionised sea-faring, for instance – since they allowed sailors to estimate their longitude, and in doing so it fuelled the age of discovery and colonialism. It also fuelled advances in astronomy, as stargazers could measure the path of heavenly bodies with greater precision.

Precise frequency



Even the best mechanical clock would not be suitable for today’s standards, however. A grandfather clock, for instance, loses about 15 seconds a day – an eon in comparison to the accuracy achieved by our gold standard, atomic clocks. Invented 60 years ago, they work by bathing a ball of caesium atoms in microwaves. The microwaves are tuned so that they are completely absorbed and then re-emitted by the caesium – which theory tells us should happen when the microwaves reach a frequency of precisely 9,192,631,770 oscillations per second. Measuring those oscillations therefore offers a very precise “tick” that is used to gauge the passing of time – in much the same way that the regular swing of the pendulum powers a mechanical clock.