THE COUNTDOWN to 2006 will seem a trifle longer this year, and not just because of the champagne. A leap second will be added at the end of 2005, the first for seven years.

We should savour the last leap second in history. Next month the International Telecommunications Union, the body governing time signals, will discuss whether to abolish leap seconds because of the trouble they may be storing up for global positioning satellites. The proposal has brought protests from astronomers, who believe that the abolition would serve only a small, self-interested group and mess up astronomical observations.

At the heart of the clash lie the two competing methods used to measure the passage of time. The first relies on the rotation of the Earth, which determines night and day. This is called Co-ordinated Universal Time (UTC), and is the source of everyday, or civilian, timekeeping. The tides and the gravitational pull of other objects, however, can make the Earth spin slower or faster. This is where leap seconds come in — they haul UTC back into line with the position of the Sun in the sky. If you abolish leap seconds and fast-forward hundreds of thousands of years, then, according to clocks running on UTC, day will have turned into night.

The second, and scientifically preferred, way of keeping time uses atomic clocks, which tick off seconds according to the decay rate of caesium-133 atoms (International Atomic Time, or TAI). This decay rate is virtually set in stone — the best atomic clocks should tick for 20 million years without losing a second. TAI started in 1958; its unrelentingly regular march, measured by around 200 caesium clocks around the world, means it is now 32 seconds ahead of UTC.

At switch-on in 1980, global positioning systems, which have an atomic clock on each satellite, were synchronised to UTC. They do not, however, correct for leap seconds and now lag 13 seconds behind UTC. The increasing role of satellite navigation in such systems as air-traffic control has led to concern about the time gulf opening up between GPS and UTC clocks. The pro-leapers argue that there is no credible evidence that Heathrow will go into meltdown because of leap seconds, and that society should be consulted if civilian clocks are no longer to keep pace with sunrise and sunset.

Ditching leap seconds would also interfere with celestial observations, which are timed according to the Earth’s rotation. The Royal Astronomical Society, based in London, wants to save the leap second. “We need [everyone[ to work together to improve current timekeeping for everyone’s benefit and not just for one group,” says Mike Hapgood, of the RAS.

• I HAVE A weakness for “sugar”. So much more elegant an utterance than “shit”, don’t you think? Especially in the company of my daughter, who has a knack for ferreting out the choicest words from her mother’s vocabulary and springing them on perplexed strangers unused to chants of “bum”.

  Yet swearing is a noble linguistic tradition — most curses are so ancient that their birthdates and inventors remain unknown. The practice appears to have a deep, neurological significance — Parkinson’s and Alzheimer’s patients often retain the ability to swear long after their reservoir of normal words has been emptied. Then there is coprolalia, a pathological urge to swear, most notably exhibited (although not always) by patients with Tourette’s syndrome.

  Psychologists believe swearing to be a comparatively peaceful way of relieving stress, which is why we let rip more often among friends. Chimps are thought to curse at each other, and they also have their own rude gestures. Professor Frans de Waal, a celebrated primatologist at Emory University in Atlanta, has noted that animals that do not cuss go straight into attack mode. By analogy, he suggests that someone who is too enraged to swear poses more of a menace to society — he might empty a gun rather than loosen his tongue.

  There is, accordingly, much dispute over whether foul language sullies civility. The United States Senate wishes to raise the penalty that broadcasters must pay for each aired obscenity, to as high as $500,000. Researchers point out that such measures are attempting to reinstate a linguistic propriety that has never existed and are thus, scientifically speaking, buggered.

Times Recommends

• It’s the beginning of the affair
• Afghanistan: still a price worth paying
• Heroes of the downtrodden