The days are not always the same because the Earth does not always rotate perfectly at the same speed: almost imperceptible variations of milliseconds that, however, can create problems for computer and scientific systems and therefore require periodic synchronization of the ‘world reference clock ‘. ‘, UTC. 27 changes in just 50 years, and ‘negative’ corrections are now also hypothesized. Too many according to Meta, the company that owns Facebook, asks in a blog to stop these updates, guilty of causing serious damage every time.
The day is defined as the time it takes for our planet to complete one rotation, a movement that we measure on average in 86,400 seconds, or 24 hours, but that seen up close is never so precise and regular. In fact, due to many factors – from the loss of ice, through earthquakes or tides, to changes in the volume of the seas – the rotation of our planet constantly fluctuates but in general we notice that it is slowing down little by little .
It is estimated that the violent earthquake of 2011 in Japan, of magnitude 8.9, accelerated the daily rotation by 1.8 microseconds, but for billions of years the length of the days has been increasing on average by about 2.3 milliseconds each hundred years, so much so that more than a billion years ago, the days were much shorter, perhaps as little as 19 hours. But the phenomenon is not so linear because the forces that intervene in determining the speed of rotation are many, and not always well measurable, and in recent years there have also been days that are faster than usual.
Just in June 2022 there was the shortest day in history, about 1.59 milliseconds less. The cause could have been some violent eruptions like the volcano in Tonga or global climatic phenomena like El Niño but probably also cyclical oscillations due to gravitational effects. Subtle changes for everyone, but not for very high-precision scientific instruments and for many computer systems that need super-precise time measurements to function, so much so that they have forced the UTC universal time signal to be modified 27 times in 50 years by introducing ‘interlayer seconds’. ‘, actually changes of very small fractions of a second.
“A solution – observe Oleg Obleukhov and Ahmad Byagowi, researchers from Meta – that was acceptable in 1972”. But not anymore. According to Meta managers, each modification brings with it very complex problems and can expose computer systems to serious dangers to cause more harm than good. Only the recording of the shortest day in history, last June, had caused some researchers to suggest that they even hypothesized the introduction of a ‘negative’ leap second, a kind of correction of the correction. A never-before-experienced change in large-scale information systems that, according to Obleukhov and Byagowi, “could have a devastating effect on software based on timers or schedulers.”
According to Meta researchers, “every leap second is a major source of problems for those managing hardware infrastructures.” There are new potential workarounds to these traumatic changes, they say, and for this reason “we support stopping further introductions of leap seconds for at least the next thousand years.”
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