This picture taken Monday Jan. 16, 2012, shows the headquarters of the International Telecommunication Union in Geneva. ITU’s member states are meeting in Switzerland this week to consider abolishing the leap second. (AP Photo/Frank Jordans)
GENEVA (AP)—It’s high noon for the humble leap second.
ten years of talks, governments are headed for a showdown vote this
week on an issue that pits technological precision against nature’s
United States, France and others are pushing for countries at a U.N.
telecom meeting to abolish the leap second, which for 40 years has kept
computers in sync with the Earth day.
seconds are necessary to prevent atomic clocks from speeding ahead of
solar time. They are added at irregular intervals, effectively
stretching atomic time by a heartbeat to make up for the irregular
wobble in the Earth’s rotation.
warn that scrapping the leap second would break the last link between
the passing of time and the course of the sun across the sky. But
backers say machines shouldn’t any longer be tethered to the imprecise
cycle of sunrise and sunset.
would be an important decision because the problem of introducing the
leap second would disappear and we would have a more steady time than we
have today,” Vincent Meens, an official at the International
Telecommunication Union who has chaired technical talks on the issue,
of cell phone networks, financial markets and air traffic control
systems could then rely on the near-absolute precision offered by atomic
clocks without having to worry about stopping their systems for the
length of a heartbeat every year or two.
of the people who operate time services favor discontinuing leap
seconds,” said Judah Levine, a physicist at the National Institute of
Standards and Technology in Boulder, Colorado.
main problem is that the leap second is usually implemented by stopping
the clock for one second. However, the world doesn’t stop,” he said.
navigation systems like GPS don’t use leap seconds, which adds
confusion, said Levine. “In addition, the leap second occurs in the
middle of the day in Asia and Australia, which is particularly
a world increasingly reliant on computers for mission-critical
measurements, any glitch could be costly as well as fatal, said Elisa
Felicitas Arias, director of the time department at the Paris-based
International Bureau of Weights and Measures.
can make a dramatic error if, for example, you are trying to land an
aircraft,” she said, noting that rocket launches, too, are never
scheduled on days when a leap second might occur. “This is something we
are trying to correct.”
say the risks are overblown and leap seconds have been used
successfully since 1972, despite being hard to predict more than six
months in advance.
has warned that any change could hurt astronomers, who need to be able
to compare observations spanning thousands of years as part of their
too, has raised objections to the proposed plan, while Britain has
warned that it could spell the end of Greenwich Mean Time, or GMT, as a
seconds are an inconvenience to the telecommunications people, but
there are many other users of time who should be considered,” said Ken
Seidelmann, a research professor at the University of Virginia in
Charlottesville and former director of astrometry at the U.S. Naval
off the leap second would also result in atomic clocks slowly
outrunning the solar day by a rate of about 90 seconds a century. After
many thousands of years, atomic clocks would say it’s midday when
outside the sun has yet to rise.
is replacing a small problem with a big problem further down the line,”
said Daniel Gambis, an astronomer at the Paris Observatory and the man
who alerted timekeepers around the world to the next leap second, due on
said solutions could be found for such problems, but conceded that
severing the link between the proposed new standard time—as measured by
atomic clocks—and the solar time people are accustomed to might seem
troubling to many.
Still, the time for change has come, she argued.
a last minute consensus is reached, delegates at the ITU meeting in
Geneva are expected to vote on the issue Thursday or Friday.
International Telecommunication Union
SOURCE: The Associated Press