Bush Wants to Alter Definition of Time
- From: "MrPepper11" <MrPepper11@xxxxxx>
- Date: 29 Jul 2005 10:02:53 -0700
The "leap seconds" added every few years to compensate for the Earth's
slowing rotation can be a hassle for computers. But a secret U.S.
proposal to end the system has set off a wave of passionate opposition
from astronomers.
July 29, 2005
Why the U.S. Wants To End the Link Between Time and Sun
Astronomers Say Wait a Sec, Sundials Would Be Passé; Mean Blow to
Greenwich
By KEITH J. WINSTEIN
Staff Reporter of THE WALL STREET JOURNAL
What time is it when the clock strikes half past 62?
Time to change the way we measure time, according to a U.S. government
proposal that businesses favor, astronomers abominate and Britain sees
as a threat to its venerable standard, Greenwich Mean Time.
Word of the U.S. proposal, made secretly to a United Nations body,
began leaking to scientists earlier this month. The plan would simplify
the world's timekeeping by making each day last exactly 24 hours. Right
now, that's not always the case.
Because the moon's gravity has been slowing down the Earth, it takes
slightly longer than 24 hours for the world to rotate completely on its
axis. The difference is tiny, but every few years a group that helps
regulate global timekeeping, the International Earth Rotation and
Reference Systems Service, tells governments, telecom companies,
satellite operators and others to add in an extra second to all clocks
to keep them in sync. The adjustment is made on New Year's Eve or the
last day of June.
But adding these ad hoc "leap seconds" -- the last one was tacked on in
1998 -- can be a big hassle for computers operating with software
programs that never allowed for a 61-second minute, leading to glitches
when the extra second passes. "It's a huge deal," said John Yuzdepski,
an executive at Symmetricom Inc., of San Jose, Calif., which makes
ultraprecise clocks for telecommunications, space and military use.
On Jan. 1, 1996, the addition of a leap second made computers at
Associated Press Radio crash and start broadcasting the wrong taped
programs. In 1997, the Russian global positioning system, known as
Glonass, was broken for 20 hours after a transmission to the country's
satellites to add a leap second went awry. And in 2003, a leap-second
bug made GPS receivers from Motorola Inc. briefly show customers the
time as half past 62 o'clock.
"A lot of people encounter problems with their software going over a
leap second," said Dennis D. McCarthy, who drafted the U.S. leap-second
proposal while serving as the Navy's "Director of Time." Because of
these problems, the U.S. government last year quietly proposed
abolishing leap seconds to the International Telecommunications Union,
the U.N. body that tells the Earth Rotation Service how to keep time.
"Safety of life is an issue," said William Klepczynski, a senior
analyst at the State Department in favor of the U.S. proposal, who
asserts that programmers who ignore the need to add leap seconds
present a "risk to air travel in the future" because a glitch might
shut down traffic-control systems.
Eliminating leap seconds will make sextants and sundials slowly become
inaccurate, but supporters say that's OK now that the
satellite-supported GPS can give exact longitude and latitude bearings
to anyone with a receiver. Sailors "don't navigate with the stars any
longer," said Dr. McCarthy.
But the U.S. proposal, which an ITU committee will consider in
November, has upset some of the most powerful people in timekeeping --
including the Earth Rotation Service's leap-second chief, Daniel
Gambis, of the Paris Observatory. "As an astronomer, I think time
should follow the Earth," Dr. Gambis said in an interview. He calls the
American effort a "coup de force," or power play, and an "intrusion on
the scientific dialogue." A 2002 survey of his subscribers found that
90% were content to keep leap seconds, he said.
On July 5, Dr. Gambis sent an email out to those timekeepers, tipping
them off about the U.S. proposal, which would end leap seconds starting
in 2007. Dr. Gambis urged email recipients to contact their countries'
ITU delegations.
This has set off a wave of passionate opposition from astronomers, who
argue that removing the link between time and the sun would require
making changes to telescopes, changes that would cost between $10,000
and $500,000 per facility. That's because a fancy telescope uses the
exact time and the Earth's position for aiming purposes when
astronomers tell it to point at a specific star.
"We should not so blithely discard the ties between our clocks and the
rotation of the Earth," wrote Rob Seaman, a programmer at the National
Optical Astronomy Observatories in Tucson, Ariz. Jean Meeus, an
influential Belgian astronomer, called the U.S. proposal "a disaster
for classical astronomy" and a "dirty trick."
The U.S. effort to abolish leap seconds is also firmly opposed by
Britain, which would further lose status as the center of time. From
1884 to 1961, the world set its official clocks to Greenwich Mean Time,
based on the actual rise and set of the stars as seen from the Royal
Observatory in Greenwich, just outside London.
When countries moved to the current Coordinated Universal Time, which
uses extremely precise atomic clocks, they agreed to insert leap
seconds in order to keep the official time within one second of the old
Greenwich time. Even though Big Ben -- and the time broadcast by the
British Broadcasting Corp. -- now follow Coordinated Universal Time,
Parliament has declined to change the country's official standard away
from Greenwich time, which remains a point of English pride.
Abandoning leap seconds would force the issue and make the world slowly
drift away from Greenwich time. So Britain's science minister, Lord
Sainsbury of Turville, decided in April, during Tony Blair's
re-election campaign, to oppose the U.S. proposal. "It could have been
used to attack the government," said Peter Whibberley, a scientist who
represents Britain to the ITU. "People regard GMT with some
sensitivity," he said. "It gets tied up with the general anti-Europe
feeling."
Ending leap seconds would make the sun start rising later and later by
the clock -- a few seconds later each decade. To compensate, the U.S.
has proposed adding in a "leap hour" every 500 to 600 years, which also
accounts for the fact that the Earth's rotation is expected to slow
down even further. That would be no more disruptive than the annual
switch to daylight-saving time, said Ronald Beard of the Naval Research
Laboratory, who chairs the ITU's special committee on leap seconds and
favors their abolishment. "It's not like someone's going to be going to
school at four in the afternoon or something," he said.
For now, U.S. officials still regard their proposal as secret, despite
Dr. Gambis's email and the public comments. The head of America's
delegation to the ITU's timing committee, D. Wayne Hanson of the
National Institute of Standards and Technology, declined to take calls
on the matter. Through a spokeswoman, he said that the U.S. proposal is
a private matter internal to the ITU and not for public discussion.
That secrecy outrages the astronomers, who complain that there is no
reason to make the change by 2007, especially when many telescopes will
have to be upgraded. The State Department's Dr. Klepczynski argues that
it's better to eliminate possible computer bugs before an accident
happens. "Some people are afraid to act on prevention," he said.
The astronomers are not convinced. "If your navigation system causes
two planes to crash because of a one-second error, you have worse
problems than leap seconds," said Steve Allen, a University of
California astronomer who maintains a Web site about leap seconds.
Deep down, though, the opposition is more about philosophy than cost.
Should the convenience of lazy computer programmers triumph over the
rising of the sun? To the government, which worries about safety more
than astronomy, the answer is yes. In Mr. Allen's view, absolutely not.
"Time has basically always really meant what you measure when you put a
stick in the ground and look at its shadow," he said.
.
- Follow-Ups:
- Re: Bush Wants to Alter Definition of Time
- From: rick++
- Re: Bush Wants to Alter Definition of Time
- From: Glenn
- Re: Bush Wants to Alter Definition of Time
- Prev by Date: Re: Are too many people retired ?
- Next by Date: Re: Are too many people retired ?
- Previous by thread: Multiculturalism will kill you if you don't watch out.
- Next by thread: Re: Bush Wants to Alter Definition of Time
- Index(es):
Relevant Pages
|
