It has been widely reported that a leap second was added to clocks at midnight to prevent the time from drifting with respect to the Earth’s rotation. Big Ben, or more precisely the Great Clock at the Palace of Westminster, had to be adjusted in advance of the night, to ensure Big Ben chimed at the correct moment to ring in the New Year.
In order to measure this change for myself, I set my watch to the time signal on BBC Radio 4 on Tuesday. Yesterday, they broadcast Big Ben’s chimes at 6pm on the same station, as they always do. Sure enough, the chime came a second late. The leap second had already been added! At midnight, the famous clock was broadcast on TV, and once again was a second behind my watch, although it was now my watch that was a second fast.
Unfortunately, little experiments such as this may not be possible in the future without visiting London. I was using analogue radio and television. The government plans to have switched off all analogue TV by 2012, and there are now plans afoot to do the same to FM radio in in the next decade or two. Unlike analogue broadcasts, which arrive almost instantaneously, processing and the way digital signals may “bounce around” before being decompressed at the receiver means that the received broadcast will lag behind its transmission. This is the reason the BBC dropped their famous clock idents from BBC1 television some years ago. Internet broadcasting lags even further behind, routinely by half a minute or more.
This delay in transmission will mean that anyone who relies on the televised Big Ben to mark the start of the New Year is likely to be celebrating slightly late. While some may say this doesn’t matter, what is the point of watching Big Ben at all, if it is not to hear the exact moment the New Year begins throughout the country? Why not record the programme and celebrate the New Year another night? Instead, for the accurate time, it will be necessary to use a clock set by the Radio Time Signal, or the clock on a computer set by Network Time Protocol.
So the only way to hear Big Ben to ring in the New Year will be to go to London. But even then, how accurate is it? Unless you’re standing right next to the tower, the sound of the bell will take a time to reach you. In fact, anyone who is a certain distance from Westminster, and who simultaneously listens to an analogue radio broadcast, can hear 13 chimes at midnight. Being just a kilometre from the tower means a delay of three seconds, and even standing at the base, there is almost a third of a second delay before you hear the chime! Analogue broadcasts have provided the only way of hearing the chimes at the time they sounded. In future, anyone who isn’t lucky enough to have access to the clock tower at the Palace of Westminster will have to make do with the their radio controlled watch or computer to ring in the New Year – and that just doesn’t seem quite the same!