#1 The most accurate atomic clock of its kind in the world is unveiled today
09-14-2008, 10:27 PM
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- Aug 2005
World's most accurate clock unveiled improve the accuracy of navigation around the world.
Experimental design based on a single mercury ion which is better than 1 second in 400 million years,
The most accurate atomic clock of its kind is unveiled today, marking a new leap forward in efforts to synchronise telecom networks and deep-space communications, as well improve the accuracy of navigation around the world.
JILA's strontium atomic clock is now the world's most accurate clock based on neutral atoms
The new clock is based on a few thousand strontium atoms trapped in grids of laser light and is twice as accurate the current US time standard based on a "fountain" of caesium atoms.
This clock tops previous records for accuracy in clocks based on atoms. Although not as accurate as an experimental design based on a single mercury ion (a charged mercury atom), which is better than 1 second in 400 million years, technology to interconnect so called "neutral atom" clocks, such as the strontium one, into a "clock of clocks" promises to make them the most precise of all.
Ultra cold atoms are the "pendulums" for atomic clocks because they only absorb highly precise frequencies of light and, because a frequency is the number of oscillations per second, they can be used to measure the passing of time.
Because the strontium atoms absorb higher frequency light than earlier clocks, which rely on longer microwaves, these optical clocks have shorter and more accurate "ticks" - 430 trillion per second.
The next-generation atomic clock is reported today in the journal Science by Dr Jun Ye and colleagues at JILA, a joint institute of the Commerce Department's National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder.
The team could link the new clock with existing clocks, using a special fibre optic link, which is crucial if the new clock is to be used as a timekeeping standard, since that has to depend on polling the ticks of lots of clocks.
The JILA and NIST are home to optical clocks based on a variety of atoms, including strontium, calcium, mercury, aluminum, and ytterbium, each offering different advantages
09-14-2008, 10:29 PM
Oh great - the monkey on our back is now even more accurate.At Coretta Scott King's funeral in early 2006, Ethel Kennedy, the widow of Robert Kennedy, leaned over to him and whispered, "The torch is being passed to you." "A chill went up my spine," Obama told an aide. (Newsweek)
09-14-2008, 10:30 PM
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- Aug 2005
Stephen Hawking to unveil strange new way to tell the time
Prof Stephen Hawking is to unveil a remarkable £500,000 clock with no hands that pays tribute to the world's greatest clockmaker.
One clock made by the legendary John Harrison, the pioneer of longitude, took 36 years to build and he was still calibrating it when he died at his home in London on March 24, 1776, his 83rd birthday.
The Corpus Clock has been invented and designed by Dr John Taylor for Corpus Christi College Cambridge for the exterior of the college's new library building.
It will be unveiled next week (19th Sept) by Prof Stephen Hawking, cosmologist and author of the global bestseller, A Brief History of Time.
Dr Taylor, an inventor and horologist who studied at the College in the 1950s has put £500,000 of his own money and seven years into the project.
"One of my heroes is John Harrison," he says.
Of Harrison's many innovations, he came up with the 'grasshopper escapement', explained Dr Taylor, referring to the device used by Harrison to turn rotational motion into a pendulum motion for timekeeping.
"No one knows how a grasshopper escapement works, so I decided to turn the clock inside out and, instead of making the escapement 35 mm across, it is 1.5 m across," said Dr Taylor.
He calls the new version of the escapement a 'Chronophage' (time-eater) - "a fearsome beast which drives the clock, literally "eating away time".
It is the largest Grasshopper escapement of any clock in the world.
advertisementThe Chronophage "hypnotises the watcher with its perpetual motion, punctuated by an extraordinary repertoire of slow blinks, jaw-snaps and stings from its tail," says Dr Taylor.
09-14-2008, 10:33 PM
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- Aug 2005
Clock from 1776 just goes on and on, Harrison's Late Regulator clock
The final masterpiece of the world's greatest clockmaker is to be put through its paces at last, 230 years after it was finished, to see if it fulfils its maker's specifications.
The priceless Late Regulator clock took John Harrison, the pioneer of longitude, 36 years to build and he was still calibrating it when he died at his home in London on March 24, 1776, his 83rd birthday.
Harrison believed that the Late Regulator would vary by only a second every 100 days and a trial has started at the Royal Observatory, Greenwich, to see if it was capable of the feat, which was first managed by an electro-mechanical timepiece in the 1920s.
The Late Regulator, also known as the RAS Regulator, because it is on loan from the Royal Astronomical Society, has been restored to its former glory to coincide with the opening at the observatory on Wednesday of a series of new galleries dedicated to time and space.
The timepiece's blend of lignum vitae wood, brass, bronze and steel components was designed to compensate for changes in temperature and atmospheric pressure over the seasons.
Jonathan Betts, the head of horology at the National Maritime Museum, Greenwich, said: "Originally Harrison used the movement of stars past a neighbour's chimney and his window frame to measure the effects of calibration, to see if the Late Regulator ticked with the same regularity in the summer as the winter. It was a huge task and very time-consuming."
To calibrate the clock, albeit with the help of modern technology, Mr Betts has had to decipher Harrison's last known manuscript, A Description Concerning Such Mechanism as Will Afford a Nice or True Mensuration of Time.
Mr Betts said: "On first reading it sounds like gibberish but some of the concepts were new, so he had to invent names for them, such as dominion."
Harrison went against the grain of contemporary thinking by using large pendulum swings, enlarging the pendulum's "dominion" to reduce errors.
The clock has been installed on an ultra-stable concrete mounting for the observatory test.
"A lot of Harrison fans are keen to know how it will do," Mr Betts said.
Harrison used his clocks as time standards for the marine chronometers he had pioneered to deliver accuracy great enough to allow the determination of longitude at sea.
It was his fourth timekeeper, known today as H4, that finally won him the £20,000 Longitude Prize, a fortune for those days because the project was the greatest scientific, economic and political problem of the age.
The Late Regulator would have been used as the time standard for the H6 pocket timekeeper - "the lesser watch", as he called it.
09-14-2008, 10:56 PM
The Jesuits started this idiocy - blame them.At Coretta Scott King's funeral in early 2006, Ethel Kennedy, the widow of Robert Kennedy, leaned over to him and whispered, "The torch is being passed to you." "A chill went up my spine," Obama told an aide. (Newsweek)
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