Later this month, delegations from around the world will attend a conference in Dubai to discuss international treaties related to radio frequencies, satellite coordination and other complicated technical issues. These include the persistent clock problem.
For 50 years, the international community has carefully and precariously balanced two different ways of measuring time. One method, based on the Earth’s rotation, is as old as human timekeeping itself, an ancient, common-sense dependence on the position of the sun and stars. The other, more precise method obtains a constant, reliable frequency of the changing state of cesium atoms and provides essential regularity for the digital devices that dominate our lives.
The problem is that the times of these clocks diverge. Astronomical time, called Universal Time, or UT1, has tended to lag a few clicks behind atomic time, called International Atomic Time, or TAI. Thus, every few years since 1972, the two times have been synchronized by the insertion of leap seconds, briefly stopping the atomic clocks to allow the astronomical clock to catch up. This creates UTC, Coordinated Universal Time.
But it’s difficult to accurately forecast when the leap second will be necessary, and this has created a growing headache for technology companies, countries and timekeepers around the world.
“Having to deal with leap seconds drives me crazy,” he said. Judah Levine, head of the Network Synchronization Project at the Time and Frequency Division of the National Institute of Standards and technology, or NIST, in Boulder, Colorado, where he is a leading thinker on the coordination of the world’s clocks. They constantly hound him for updates and better solutions, he said: “I get millions of emails.”
On the eve of the next international debate, Dr. Levine has written an article proposing a new solution: the leap minute. The idea is to synchronize the clocks less frequently, perhaps every half century, essentially letting atomic time diverge from cosmos-based time for 60 seconds or even a little more, and basically forgetting about it in the meantime.
“We all need to relax a little,” Dr. Levine said.
One world, two watches
The problems date back to the early 1970s, with the introduction of atomic time. Until then, the world had relied heavily 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 small irregularities caused by the slowing of the Earth’s rotation and other natural forces. These variations went largely unnoticed by humans. Not so much because of the machines.
Computers require precise and synchronized timing so that their commands stay in order. After the introduction of atomic time, it became essential for an increasing number of functions (such as landing airplanes and timing stock trading), but not without an increasing number of problems as society became more mechanized.
“Cesium clocks became very common and immediately a problem arose,” Dr. Levine said. “The astronomical clock and the cesium clock began to move away from each other.”
The introduction of the leap second in 1972 codified that a second would be introduced every time the two clocks diverged by more than 0.9 seconds. This had at least three goals: to keep time connected to the natural world and the tradition of astronomy; to adapt to digital technology; and reconcile and synchronize the two clocks. In the last 50 years, leap seconds have been used 27 times.
At the beginning of this century, another problem emerged, driven by a new set of stakeholders: big technology companies. Companies like Google, Amazon, and Facebook developed their own methods to reconcile astronomical and atomic time, essentially avoiding the leap second. Meta, for example, “fades” the leap second in millisecond increments over a 17-hour period., instead of jumping abruptly. But there are many methods that create a free-for-all timing that threatens uniformity.
“We made a time disaster all over the world,” said Patrizia Tavella, director of the Time Department at the International Bureau of Weights and Measures in Paris.
Dr. Levine, with his leap minute solution, is highly regarded among timekeeping scientists, said Demetrios Matsakis, former director of the Time Service Department at the US Naval Observatory. (In 2009, Dr. Levine won the prestigious Time Lord Award, given by the International Timing and Sync Forum.)
For this and other reasons, Dr. Matsakis finds the new proposal compelling. “If they come hard for a minute, that would be a new emphasis,” he said. It’s “the kind of problem that could have a political solution,” he added. “I may be the winner.”
On the other hand, he said, the proposal could stall like previous proposals aimed at reconciling the clocks, paralyzed by an international community of vested interests and strong opinions.
“It’s largely hysteria,” Dr. Matsakis said.
The Vatican and the Russians
At some point last year, Dr. Tavella spoke with the Rev. Paul Gabor, an astrophysicist and deputy director of the Vatican Observatory Research Group in Tucson, Arizona, about the leap second. His concern, he said, was that “eliminating the idea could create some unease, as humans feel connected and want to stay connected to the natural world.” He also: “Men look at the sky and count the days; This is something ‘unspoken’ but deep in the hearts of men.”
Other timekeepers and diplomats felt that losing the leap second would disconnect official time from the ancient traditions of astronomy and eventually lead to the preeminence of precise but laboratory-created atomic clocks. Among the fiercest opponents Over the years it has been the British government that has controlled Greenwich Mean Time (what is now Coordinated Universal Time), an astronomical clock that is determined by averaging the position of the sun throughout the year.
Dr. Levine said he sympathized. “The public has a great distrust of scientists as people who propose something that seems to go against common sense,” he said.
And yet, he said, the persistence of daylight saving time appears to be an admission that people are comfortable “changing the connection between time and everyday astronomy.”
Over the past decade, the increasing challenges of implementing the leap second have fueled the will to change the current system. Last November a radical change occurred. when member states of the International Bureau of Weights and Measures declared they were ready to explore alternatives to the leap second. No proposals were adopted, but the groundwork was laid to consider options, such as eliminating the leap second or relaxing the relationship between astronomical and atomic time.
There were holdouts, particularly the Russians, who have argued vigorously, if mysteriously, in favor of retaining the leap second. The Russian Glonass satellite system is supposedly built to take leap seconds into account and altering the current timing methodology could have military implications.
“No one fully understands this,” said Elizabeth Donley, head of NIST’s Time and Frequency Division. “It’s probably a matter of national security. “They never really give a good answer.”
Which brings the global community to the World Radiocommunication Conference, which will be held starting November 20 in Dubai. The agenda calls for discussions about the leap second, but American scientists are not optimistic that the conversation will yield results. Any proposed changes would require consensus among all nations attending, including Russia.
Dr. Matsakis is more hopeful that a new method can be codified in the next two years at other conferences that do not require full consensus. For now, the leap minute proposal has just begun circulating as part of a draft that has not yet received the full scrutiny it will have to endure. Its formal publication may come after Dubai, although word will have spread by now.
For Dr. Levine, the decision can’t come soon enough; He’s tired of dealing with the leap second and feels like his time is running out. “It’s now or never,” he said. “I’m 84 years old.” He paused: “I’m actually 83, but my wife is 84 and I tend to think we’re the same age.”
UST: Spouse Universal Time.
Still, he said, “I won’t be here forever.”