An extra day is tacked on to the end of February, known as the leap year. The practice of adjusting the calendar with an extra day was started more than 2,000 years ago by Julius Caesar and was modified in the 16th century by Pope Gregory XIII.
The extra day is used to align the calendar year with how long it takes Earth to travel around the sun. The added day ensures that the seasons stay the same.
It's difficult to impose order on the small end of the scale. The second is in trouble lately. The unit used to be defined in terms of how long it took Earth to spin once on its axis. The world's metrologists started measuring time from the ground up in 1967. The official length of the basic unit was 9,192,617,770 vibrations of an atom of 133 cesium. One day, 86 thousand four hundred such seconds will be written.
The Earth's rotation slows from year to year and the second grows longer than the atomic one. An extra second was added to the end of an atomic day to compensate. When atomic time is a full second ahead, it stops for a second to let Earth catch up. In 1972 ten leap seconds were added to the atomic time scale.
It's a big task to add that extra second. The leap second is both irregular and unpredictable because Earth's rotation is not always straight. Those qualities made it difficult to insert the leap. The endeavor is a technical nightmare because of the importance of precise timing.
The former director of the time department of the International Bureau of Weights and Measures said that measuring the flow of time is essential for transportation, location, defense, finance, and space competition. The world is ruled by time.
The process of squaring the two time scales has become so chaotic that the world's time experts are considering abandoning the leap second by 2035. Civilization would embrace atomic time and the tolerance between atomic time and Earth time would not change until timekeepers came up with a better plan for reconciliation. Resolution D is expected to be voted on at the meeting in Versailles.
Patrizia Tavella, the current director of B.I.P.M.'s time department, said that everyone agrees that we have to do something.
The timekeeping of atoms and the timekeeping of the heavens would be severed by the resolution. Most of us would find the change indiscernible. It would take a long time for atomic time to change from Earth time to atomic time.
There is a lot of time spent on the internet. Cellphone transmissions, power grids, and computer networks are all synchronized to a small fraction of a second. Financial markets have high-frequency traders who execute orders in a thousandths of a second. Data packages related to these financial transactions must be recorded and traced back to Coordinated Universal Time, the universally agreed upon standard managed by the timekeepers at the B.I.P.M.
The risk of confusion arises from the fact that some digital networks won't implement the change correctly, won't know precisely what time it is with regard to the other systems, and will fail to sync properly. There's a lot of potential chaos in a soufflé.
The United States is one of the nations that supports the discarding of the leapsecond. The result of the vote isn't a sure thing. It has taken more than two decades of study, negotiation and compromise to get Resolution D on the agenda.
Judah Levine is a physicist at the National Institute of Standards and Technology in Boulder, Colo. He is one of the co-chairs of the B.I.P.M. committee that discusses hot topics.
Russia has tried to delay a shift away from the leap second because doing so would require extensive alterations to its satellite system. The resolution has been phrased to hold off on any changes until the year 2035. The United Kingdom has been reluctant to make a public commitment to the standard.
There is more to the fate of the leap second than just its fate. Coordinated Universal Time, the international standard for timekeeping, is in danger of being undermined.
The U.T.C. is constructed from readings made by atomic clocks at national laboratories around the world. The best seconds are sent to the B.I.P.M., where timekeepers painstakingly assemble the readings into an ideal second. It takes time for this process to be completed. In order to improve its aim the following month, the Bureau publishes the perfect time in the form of a newsletter, called Circular T, that tells each national clock how much it deviates from international standards.
Coordinated Universal Time is the world's official time scale and will continue to include leap seconds. A description of global time zones is provided. The time in New York is not up to date. The second is the most important measurement in the constellation of standard measures overseen by the B.I.P.M.
A century and a half ago, national signatories to an international treaty called the Meter Convention decided that every unit of measurement in the world should be the same. The seven standard units are important to fair commerce. The mole is the only unit that is not underpinned by the second. The meter is defined as the distance light travels in a vacuum during one second, and the kilogram was recently redefined in terms of the second.
The second is connected to a time scale. Modern life requires that the unit of time be the same no matter where it is measured and that the flow of seconds be the same as well.
The leap second puts that tenet at risk. According to a recent article in the journal Metrologia, unofficial, but free of leap seconds and easier to implement, timekeeping methods have begun to displace U.T.C., because of the technical difficulty of incorporating the kludge. The standard time scale would be made friendlier by removing the leap second from U.T.C. Universal time wouldn't be coordinated with earth time.
The problem is that pseudo time scales are not time scales in the metrological sense.
The time scale used in place of U.T.C. is the American government's global positioning system. The U.S. Space Force operates and maintains every satellite in the global positioning system.
It is possible to determine the time of day within 100 billionth of a second with the help of the gps system. It is not funneled through the B.I.P.M. The official time of the United Nations is U.T.C., but the International Telecommunication Union suggests that it is not an official time because it doesn't include leap seconds.
Although gps keeps good time, using it instead of U.T.C. would mean that time wouldn't be overseen by an organization that abides by international agreements.
According to the Metrologia article, the U.S. military controls a primary source of international time signals.
The clock aboard satellites is not consistent. Russia's GLONASS runs on U.T.C., but the other satellites don't, and they differ from universal time by different amounts. Galileo is 18 seconds ahead of U.T.C. They function well because they are consistent and can be tracked.
Computing systems that insert the leap second do different things. Sometimes the time stamps required for commercial and financial transactions are out of whack during the adjustment period. The extra second is added by each company in their own way. The number of errors in implementing the leap second is increasing.
The doctor said it was anarchy.
There is an additionalwrinkle. The leap second is needed because atomic time is quicker than Earth time. The Earth's rotation rate started decelerating around the time the leap second was invented. Earth time will catch up to atomic time. If the trend continues, Earth time will overtake atomic time by about a second by the year 2030.
A second will disappear in this way. Metrologists fear a digital disaster because such an experiment has never been tested on computers. Nobody knows what to do when a negative leap second occurs.
Emotions are fraught with time. The debate over whether to keep daylight saving time has become messy.
Mexico's Senate voted last month to end the practice of sharing the border with the US for certain areas. The Senate voted in March to keep daylight saving time, but the motion is stuck in the house. Parliament in the Europe Union has been confused about how to keep the clock the same year-round.
Strong opinions are elicited by the leap second. The Vatican wants to keep the leap second. The vice director of the Vatican Observatory Research Group in Tucson, Arizona, wrote in his book that time is a constant reminder of mortality.
We might want to believe that our time, our lifetime, somehow corresponds to the eternal Cosmic cycles.
The implications of suspending the leap second were discussed with Dr. Gabor. The ancient and sacred task of timekeeping has always been fraught with compromise.
By the time Pope Gregory XIII restructured the calendar and removed the extra days, the calendar was 11 minutes and 14 seconds longer than it was when it was first created. Three leap days every 400 years was his fix. New ideas are encouraged by new information.
Time would retain its link to the stars regardless of Resolution D's outcome. She said that the rotation of the Earth isn't being abandoned. Atomic time and the rotation of the Earth are related. The differences would not be actively implemented.
Even if Resolution D is passed, future generations of timekeepers will continue to try to reconcile atomic time with the sun's position in the sky.
Failure or a delay of the resolution would lead to a dangerous new era of international timekeeping.
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