The clocks that rule our world

The best clocks now lose only a
second every 300 million years – and
the minuscule differences in their
time-keeping is changing the world
we live in. David Robson reports.
Tech
nology 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.