A giant leap for the second jump. Is humanity ready?
Later this month, delegations from around the world will go to a conference in Dubai to discuss international treaties on radio frequencies, satellite coordination and other tricky technical issues. These include the nagging problem of the bells.
For fifty years, the international community has carefully and dangerously balanced two different ways of keeping time. One method, based on the Earth’s rotation, is as old as human timekeeping itself: an ancient and common-sense reliance on the position of the sun and stars. The other, more precise method extracts a stable, reliable frequency from the changing state of cesium atoms, providing essential regularity for the digital devices that dominate our lives.
The problem is that the times on these clocks vary. Astronomical time, called Universal Time or UT1, tends to lag a few clicks behind atomic time, called International Atomic Time or TAI. Since 1972, the two times have been synchronized every few years by the insertion of leap seconds – briefly pausing the atomic clocks to allow the astronomical clock to catch up. This creates UTC, Universal Coordinated Time.
But it’s difficult to predict exactly when the leap second will be needed, and this has created increasing headaches for tech companies, countries and the world’s timekeepers.
“Making leap seconds drives me crazy,” he said Judah Levine, head of the Network Synchronization Project in the Time and Frequency Division of the National Institute of Standards and Technology in Boulder, Colorado, where he is a leading thinker on coordinating the world’s clocks. He is constantly pestered for updates and better solutions. He said, “I’m getting a billion emails.”
On the eve of the next international discussion, Dr. Levine wrote an article proposing a new solution: the leap minute. The idea is to synchronize the clocks less frequently, perhaps every half century, essentially causing atomic time to drift from cosmos-based time by 60 seconds or even a tad longer, effectively being forgotten in the meantime.
“We all need to relax a little,” said Dr. Levine.
One world, two clocks
The problems date back to the early 1970s, with the introduction of the atomic age. Until then, the world had been largely dependent on astronomical time. It seemed logical: the sun rose and it was day, then it set and it was night, and so on, although there were minor irregularities caused by the slowing of the Earth’s rotation and other natural forces. These variations went largely unnoticed by humans. Not so much by machines.
Computers require accurate, step-by-step timekeeping so that their assignments remain orderly. After the introduction of atomic time, it became essential for a growing number of functions – such as landing planes and timing stock trading – not without a growing number of problems as society became more mechanized.
“Cesium bells became very common, and there was an immediate problem,” said Dr. Levine. “The astronomical clock and the cesium clock began to diverge.”
The introduction of the leap second in 1972 codified that a second would be introduced whenever the two clocks separated by more than 0.9 seconds. This had at least three objectives: to keep time connected to the natural world and the tradition of astronomy; suitable for digital technology; and to reconcile and synchronize the two clocks. In the past fifty years, leap seconds have been used 27 times.
At the turn of the century, another problem arose, driven by a new group of stakeholders: large technology companies. Companies like Google, Amazon and Facebook developed their own methods to reconcile astronomical and atomic time, essentially bypassing the leap second. For example, Meta ‘smears’ the leap second in millisecond increments over a 17-hour period, instead of jumping abruptly. But there are many methods that create free time tracking for everyone and threaten uniformity.
“We have made a mess of time all over the world,” said Patrizia Tavella, director of the time department at the International Bureau of Weights and Measures in Paris.
Dr. Levine’s leap-minute solution is highly regarded among timekeeping scientists, says Demetrios Matsakis, former director of the Time Service Department at the US Naval Observatory. (In 2009, Dr. Levine won the prestigious Time Lord award presented by the International Timing and Sync Forum).
For these and other reasons, Dr. Matsakis finds the new proposal compelling. “If they come in strong for one minute, that would be a new emphasis,” he said. It’s “the kind of thing that could be politically solvable,” he added. “It could just be the winner.”
On the other hand, he said, the proposal could stall, like previous proposals aimed at reconciling the bells, stalled by an international community of vested interests and strong opinions.
“You’re dealing largely with hysteria,” Dr. Matsakis said.
The Vatican and the Russians
At some point in the past year, Dr. Tavella with Rev. Paul Gabor, an astrophysicist and the vice director of the Vatican Observatory Research Group in Tucson, Arizona, about the leap second. His concern, she said, was that “eliminating the idea might cause some discomfort as people feel connected and want to stay connected to the natural world.” Also: “Men look at the sky and count the days; this is something ‘unspoken’, but deep in the heart of man.”
Other timekeepers and diplomats believed that losing the leap second would disconnect official time from the ancient traditions of astronomy and eventually lead to the preeminence of the accurate but laboratory-made atomic clocks. Among the fiercest opponents Over the years, the British government has controlled Greenwich Mean Time (which is now Universal Coordinated Time), an astronomical clock determined by averaging the position of the sun over the year.
Dr. Levine said he sympathized. “The public has a great distrust of scientists when people propose something that seems to fly in the face of common sense,” he said.
And yet, he said, the survival of daylight saving time seems like a recognition that people are comfortable “with changing the connection between time and everyday astronomy.”
Over the past decade, growing challenges in implementing the leap second have led to a willingness to change the current system. A sea change occurred last November when member states of the International Bureau of Weights and Measures declared their willingness to explore alternatives to the leap second. No proposal was adopted, but the foundation was laid for considering options such as eliminating the leap second or relaxing the relationship between astronomical and atomic time.
There were holdouts, most notably the Russians, who argued strongly, if mysteriously, for keeping the second jump. The assumption is that Russia’s Glonass satellite system was built to account for leap seconds and that changing the current timekeeping methodology could have military consequences.
“No one fully understands this,” said Elizabeth Donley, chief of NIST’s Time and Frequency Division. “It’s probably a matter of national security. They never really give a good answer.”
This brings the world community to the World Radio Conference, the meeting that will be held in Dubai from November 20. The agenda calls for discussions about the leap second, but American timing scientists are not optimistic that the conversation will yield results. Any proposed change would require consensus among all participating countries, including Russia.
Dr. Matsakis is more hopeful that a new method could be codified in the next two years at other conferences that do not require full consensus. For now, the leap minute proposal has just started circulating as part of a draft document that has not yet received the full criticism it will have to withstand. Its formal publication could well come after Dubai, although word of it will have spread.
For Dr. A decision can’t come soon enough for Levine; he is tired of dealing with the leap second and feels like his own time is decreasing. “It’s now or never,” he said. “I’m 84.” He paused: “Actually, I’m 83, but my wife is 84 and I tend to think of us as the same age.”
UST: Universal spouse time.
Anyway, he said, “I won’t be there forever.”