‘Leap second’ Lengthens Weekend (30th Jun 2012)
The world is about to get a well-earned long weekend but don’t make big plans because it will only last an extra second. A so-called “leap second” will be added to the world’s atomic clocks as they undergo a rare adjustment to keep them in step with the slowing rotation of the Earth.
To achieve the adjustment, on Saturday night atomic clocks will read 23 hours, 59 minutes and 60 seconds before moving on to midnight Greenwich Mean Time.
Super-accurate atomic clocks are the ultimate reference point by which the world sets its wristwatches. But their precise regularity – which is much more constant than the shifting movement of the Earth around the sun that marks out our days and nights – brings problems of its own.
If no adjustments were made, the clocks would move further ahead and after many years the sun would set at midday. Leap seconds perform a similar function to the extra day in each leap year which keeps the calendar in sync with the seasons. The International Earth Rotation and Reference Systems Service (IERS) based in Paris, is responsible for keeping track of the gap between atomic and planetary time and issuing international edicts on the addition of leap seconds.
“We want to have both times close together and it’s not possible to adjust the Earth’s rotation,” Daniel Gambis, head of the Earth Orientation Centre of the IERS, told Reuters.
Gambis said the turning of the Earth and its movement around the sun were far from constant.
In recent years, a leap second has been added every few years, slightly more infrequent than in the 1970s, despite the long-term slowdown in the Earth’s rotation caused by tides, earthquakes and a host of other natural phenomena.
Adjustments to atomic clocks are more than a technical curiosity.
A collection of the highly accurate devices are used to set Coordinated Universal Time, which governs time standards on the worldwide web, satellite navigation, banking computer networks and international air traffic systems.
There have been calls to abandon leap seconds but a meeting of the International Telecommunications Union (ITU), the UN agency responsible for international communications standards, failed to reach a consensus in January.
“They decided not to decide anything,” said Gambis, adding that another attempt would be made in 2015.
Opponents of the leap second want a simpler system that avoids the costs and margin for error in making manual changes to thousands of computer networks. Supporters argue it needs to stay to preserve the precision of systems in areas such as navigation.
Britain’s Royal Astronomical Society (RAS) says the leap second should be retained until there is a much broader debate on the change.
“This is something that affects not just the telecom industry,” said RAS spokesman Robert Massey. “It would decouple timekeeping from the position of the sun in the sky and so a broad debate is needed.”
Time standards are important in professional astronomy for pointing telescopes in the right direction but critical systems in other areas, not least defence, would also be affected by the change. “To argue that it would be pain-free is not quite true,” Massey said.
In the meantime, Massey plans to use his extra second wisely this weekend. “I’ll enjoy it with an extra second in bed,” he said.
Taken from: http://www.guardian.co.uk/science/2012/jun/29/leap-second-lengthens-saturday-time
Results from the Large Hadron Collider (LHC) have all but killed the simplest version of an enticing theory of sub-atomic physics. Researchers failed to find evidence of so-called “supersymmetric” particles, which many physicists had hoped would plug holes in the current theory. Theorists working in the field have told BBC News that they may have to come up with a completely new idea. Data were presented at the Lepton Photon science meeting in Mumbai.
This failure to find indirect evidence of supersymmetry, coupled with the fact that two of the collider’s other main experiments have not yet detected supersymmetic particles, means that the simplest version of the theory has in effect bitten the dust. Collisions inside the LHC should have found some evidence of Supersymmetry by now. The theory of supersymmetry in its simplest form is that as well as the subatomic particles we know about, there are “super-particles” that are similar, but have slightly different characteristics. The theory, which was developed 20 years ago, can help to explain why there is more material in the Universe than we can detect – so-called “dark matter”. According to Professor Jordan Nash of Imperial College London, who is working on one of the LHC’s experiments, researchers could have seen some evidence of supersymmetry by now. “The fact that we haven’t seen any evidence of it tells us that either our understanding of it is incomplete, or it’s a little different to what we thought – or maybe it doesn’t exist at all,” he said. Disappointed the timing of the announcement could not be worse for advocates of supersymmetry, who begin their annual international meeting at Fermilab, near Chicago, this weekend.
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