Days are not all the same: some last a little more than 24 hours, others a little less. A difference of a few milliseconds which, however, must be compensated from time to time for align coordinated universal time (UTC) and the mean solar day. UTC is defined by the International Telecommunications Union and is calculated by an atomic clock system. Universal time (UT1) instead derives from the measurement of the solar day on the Greenwich meridian, the zero meridian.
The Earth is spinning faster than usual and it can be a problem
An annoying interlayer
To remedy the problem, the international bodies of measurement keep track of the difference between the two times. As it approaches six tenths of a second, a “leap second” is introduced. At midnight on the pre-established day, usually June 30 or December 31, 23:60:00 are measured exceptionally, and then the clocks are triggered at 00:00:00.
Adding a second does not affect the our circadian rhythm, but creates many headaches for those who have to manage synchronized computer systems on a global scale. In 2012, the introduction of a leap second sent, for example, the systems of Reddit, Cloudflare and Quantas, the Australian airline, into a tailspin.
Future
Meta’s AI has said what it thinks of Zuckerberg. And that’s not a compliment
by Francesco Marino
It is time for a change
Now Meta says enough: the Zuckerberg company has become the bearer of a very common position among the tech greats. The leap second must be abolished, they say by Menlo Park, because it only creates problems and is an anachronistic solution (it must be said). In a post published on the Facebook blog, the production engineer Oleg Obleukhov and researcher Ahmad Byagowi explain why the addition of a “leap second” is no longer a solution suitable for the times.
“If leap second was an adequate solution in 1972, when it pleased both the scientific community and the telco industry, today UTC is inadequate for both digital applications and scientists, who often choose to use TAI (the international atomic time – nda) o l’UT1 (the average day of Greenwich – nda) ”, Explain Byagowi and Obleukhov. “Meta supports the industry’s commitment to stop the next leap second introductions, staying at the current level of 27. The introduction of new leap seconds is a practice that does more harm than good, and we believe it is time to adopt new technologies that replace it “.
Times that run (too much)
Over the long term, the rotation of the Earth tends to slow down, but within this trend, continuous variations of a few milliseconds more or less are measured. In recent decades there have been more slowdowns, hence the need to add the 27 leap seconds to which it refers Meta. In recent years, however, the Earth has been spinning a little faster. For example, June 29, 2022 was the fastest day ever: it closed 1.59 milliseconds ahead of 24 hours. On July 26, the phenomenon repeated itself: the day was 1.50 milliseconds shorter.
The reason for this acceleration is not entirely clear. According to one of the most accredited theories, it could be the fault of the Chandler Oscillation, a deviation of the position of the Earth’s poles with respect to the surface. “The normal amplitude of the Chandler Oscillation is three or four meters on the surface of the globe,” explained Dr. Leonid Zotov at timeanddate, an online publication dedicated to time and time zones, “but from 2017 to 2020 it disappeared”.
The first second negative
The concern of Meta is that these deviations from the standard may lead to the introduction of a negative leap second, the very first that should be subtracted rather than added to the calculation of time on computer systems. In recent years, to overcome the problem of adding the leap second, large computer companies have used a technique called “smearing”, literally “spreading” the difference necessary to keep the clocks synchronized over a period of several hours.
The company of Zuckerberg it does it over 17 hours, Google over a period of 24 and with a linear “spread”. Switching from 23:58:00 to 00:00:00, with the elimination of a second on a set day, would be incompatible with most synchronization systems and could create disastrous consequences for a myriad of digital applications.
According to Dr. Zotov, however, the probability that you decide to introduce a new leap second is low: there would be a 70% chance that the rotation has reached its maximum acceleration and therefore a negative correction is not needed.
The hour of revocable decisions
On the occasion of the last World Radio Communications (WRC), in Geneva in 2015, the International Telecommunications Union (ITU) postponed the next decision on the introduction of a new leap second to 2023. In the conference, the body decreed that more studies are needed to understand how to modify the UTC system (defined by the ITU) and possibly suppress the infamous leap second. A decision should arrive at the end of next year, during the WRC to be held in Dubai.
According to Meta, the 27 “leap seconds” added so far are more than enough, and should be enough for us for at least another millennium.
While the IT sector generally agrees with the company’s stance on Facebook and Instagram, there are also those who think differently. Linus Torvalds, for example: the father of Linux, in a 2015 interview with Wired had scoffed at the concerns of his colleagues. “The people and computers who really care about atomic times have to do with astronomy. Everyone else – both people and computers – would do better to say who cares, with some poor unfortunate who will have to worry about fixing bugs due to the perversions of chronological measurement, ”said Torvalds. “We take the leap second as a great opportunity to have a party with our friends. Print yourself a sign that says ‘Leap Second Apocalypse Party’ and get drunk. In the blink of an eye it will be all over, but at least the next day you will have a hangover after that reminds you of that glorious but fleeting second more. I think this is the relevance that most people should reserve for leap second ”.