(Ticking)
Time-lapse footage of clock arms turning and the sky changing colour.
REPORTER:
We spend all day watching it, losing it, spending it and finding as much of it as we can. But how much time do you spend thinking about what time actually is?
Time-lapse footage of people in a city.
The Earth turns on its axis.
REPORTER:
Well, a really, really, really long time ago people realised there are patterns in our world, like the changing of the seasons, the phases of the moon and day turning into night as the planet spins on its axis. They became the basis of how we told time.
Time-lapse footage of traffic moving through a city.
REPORTER:
Eventually our ancestors split the day into 24 hours, made up of 60 minutes each.
Girl holds a sun dial, Egyptian pyramids in the background.
REPORTER:
But we still needed an accurate way to keep track of those hours and minutes. People started with sun dials, which show the time of day by shadows.
GIRL:
Hmm...
REPORTER:
But they don't work when the sun's not shining.
(Girl sighs)
Boy lights a candle and measures its height.
REPORTER:
So people started tinkering away with other ways of keeping time, like candles and dripping water. Hour glasses were pretty effective time-keepers, which were used a lot by sailors. Except, you have to keep turning them over.
GIRL:
Oh, gosh darn it, how long have we been travelling north for?
Boy dressed in period clothing moves the pendulum of a grandfather clock.
REPORTER:
Then, centuries later, the mechanical clock changed the world.
BOY:
Hmm, not bad.
(Ticking)
REPORTER:
As time went on, our clocks got smaller and way better, so we could tell time to the second, even split second.
(Ticking, alarms ring)
Animation of an atom.
REPORTER:
We even found a way to measure time using the energy in atoms.
A scientist checks an atomic clock.
REPORTER:
Atomic clocks are the most consistently accurate time-keepers humans have ever come up with. In fact, they're even more reliable than the spinning of the Earth, which is gradually slowing down. That means 24 hours by an atomic clock is ever so slightly less than one spin of the Earth. They're only different by micro seconds, but that adds up.
Various vintage and antique clocks.
REPORTER:
So, to keep everything in sync, scientists came up with the leap second. At the end of this month, clocks all around the world will have one second added to them. It's something that's been done every few years since the '70s.
(Ticking)
REPORTER:
But there could be some side effects. There are worries the extra second will confuse some computer programs and make them crash.
(Alarms ring)
REPORTER:
Some scientists reckon the whole thing is a waste of time and we should just stick to atomic clocks to tell the time of day. Countries are going to vote on it at a big meeting later this year. But in the meantime, you might want to spend that extra second sparing a thought for time.
(Bell tolls)
