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SCIENCE

World telecoms body recommends scrapping GMT

3 min

Greenwich Mean Time (GMT) may be consigned to history as increasingly complex communications technologies require a more accurate system of measuring the time.

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Britain’s status as guardian of global timekeeping may be lost – to France – following a recommendation by the International Telecommunications Union (ITU).
 
International clocks are set according to Greenwich Mean Time, a system that measures time against the rotation of the earth according to the movement of the sun over a meridian (north-south) line (pictured) that goes through the Greenwich district of London.
 
The problem for the scientific community is that the earth’s rotation is not constant: it slows down by about a second every year.
 
US Navy scientist Ronald Beard chaired the working group at the ITU in Geneva which that last week recommended GMT be scrapped as the global time standard.
 
He told FRANCE 24 on Tuesday: “GMT has been recognised as flawed by scientists since the 1920s, and since the introduction of Coordinated Universal Time (UTC) [measured by highly accurate atomic clocks] in 1972 it has effectively been obsolete.”
 
‘Leap seconds’
 
UTC solved the problem of earth’s uneven rotation by adding the occasional “leap second” at the end of certain years to keep GMT accurate.
 
But this piecemeal system is no longer suited to the increasingly sophisticated communications technology and the needs of the scientific community.
 
“With the development of satellite navigation systems, the internet and mobile phones, timekeeping needs to be accurate to within a thousandth of a second,” said Beard. “It is now more important than ever that this should be done on a continual timescale.”
 
In effect, what the ITU is proposing is that atomic clocks should govern world time. Instead of using the GMT system and adding leap seconds, time should be allowed to be measured without interruption.
 
Beard explained that large-scale changes could be made (very occasionally) so that, for example, in 40,000 years time people would not be eating their lunch in the sunshine at “midnight”.
 
The French connection
 
Where British prestige may be hurt is that the ITU proposal would make the International Bureau of Weights and Measures (BIPM) in Paris the new guardian of world time.
 
In the UK, the news has raised eyebrows and generated a certain amount of nostalgic media heartache.
 
The Daily Mail said on Tuesday that “it would be a bitter blow for British pride and - to make matters far worse - a belated victory for the French,” who a century ago “were forced by international pressure to abandon Paris Mean Time and accept that the time in Lyons, Angers and Grenoble was determined by the sun moving overhead in London.”
 
Felicitas Arias, BPIM’s time department director, said such concerns were not justified.
 
She told FRANCE 24: “BIPM is not French, it is an international organisation and UTC is measured by atomic clocks from 68 participating countries, including the UK. Time will always be international.”
 
The ITU is due to vote on the proposals in January.

 

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