Video: How we measure time

The second is one of 7 basic units of measurement. Australia’s Chief Metrologist, Dr Bruce Warrington from the National Measurement Institute, explains how we measure time.
Screenshot from video showing the inner workings of a clock

Hello. I’m Doctor Bruce Warrington – Australia’s Chief Metrologist.

There are 7 basic units from which every measurement is made. Today I want to talk to you about the second which measures time.

A hundred years ago we told time by the swing of a pendulum, accurate to about a second a year. Then we used quartz crystals, over a thousand times more accurate. Today here at the National Measurement Institute we use atomic clocks, which tune in to a kind of heartbeat inside a cesium atom. They will take tens of thousands of years to gain or lose a single second, and they help keep Australia on time with the rest of the world.

Global positioning systems need clocks a bit like these but made to orbit in satellites. Measuring time to billionths of a second lets us know where we are to better than a metre, and makes things like driverless vehicles possible.

Every day thousands of computers connect to our clocks to get accurate time, and use it for telecommunications, transport, financial markets and many more.

Does being responsible for these clocks make me a Time Lord?

Thanks for listening, and stay tuned to hear about the other basic units of measurement!