In this timely presentation by Dr Leon Lobo from the National Physical Laboratory (NPL), we found out that it is definitely not a short-term nor a trivial matter.
The technical issues that have been overcome through the years and the refinements now under development are mind boggling. NPL are always striving for greater accuracy and stability: They are currently developing Strontium ion optical clocks amongst others.
Why couldn't we just have stayed using the sun, the moon and the stars, as had been done since the time of the Pharaohs? Well, nobody wants to miss their train and with London and Bristol differing by 11 minutes, it's tough to run a railway timetable if the time is uncertain.
These days, precise time is very important for financial markets, energy load balancing, cable fault location and interactive games, to name just a few. Sending out a news item 15 milliseconds too early resulted in $28m of trading! Profitable high speed trading relies on beating the others by the shortest of margins - and people are prepared to pay for such an advantage. Hence the laying of a new shorter, lower loss, transatlantic link to save 5 ms at a cost of hundreds of millions of dollars.
Space is also a major driver: GPS is based on time, with position being calculated from the time for signals to arrive from three to four satellites. As these signals are vulnerable to jamming, spoofing and solar activity, there is much research on going into higher resilience methods.
It was only a matter of time before we learnt that time changes over time, with relative height and with location: as shown in a 'Bang Goes the Theory' experiment where they observed a shift between a clock on the ground and one flying around the world.
Natural variations of the seasons and solar activity cause oscillations and noise; the slowing of the earth's rotation results in the gradual increase in the length of the day and hence the duration of the 86400 seconds within it. It was only in 1972 that the "Leap second" was introduced to make periodic adjustments for that. When it is needed (which can't be precisely predicted), it is added to the last minute at the end of June or the end of December (The 26th one was most recently added this June, although I can't say that I noticed!). It’s varied implementation can, however, cause a nuisance to many time-based applications. Discussions are ongoing to scrap it or maybe to leave it for longer, when it would be a larger leap; time will tell!
What about using space? In an exciting experiment, NPL are part of a science mission called ACES (Atomic Clock Ensemble in Space) where the next generation of space clocks will be mounted on the outside of the ISS (International Space Station) in order to assess how these next generation clocks and telecommunication links perform.
I won't even attempt to explain Femtosecond combs! Suffice it to say that they usefully provide very precise and stable frequency measurement.
There are many more strands of research that will keep the NPL's 400 Labs in Teddington very busy for a long time!