Taking a Non-Leap of Faith?

Time running out for ‘leap second’ that has kept us in step with our slowing planet

[T]hat [next] change could be the last of its kind for the leap second and for our fiddling with time. Telecommunications organisations and financial groups say the continual adding of leap seconds to computers increases the chances of errors being made. Precisely timed money transactions could go astray or vehicles could be sent tens of metres out of position if they are a second out in their measurement of time. Hence the bid to ban the leap second.

But there’s this – a nit at which I must pick

“However, these new, highly accurate atomic clocks also revealed that the Earth’s rotation is slowing down because of movements within the core of the Earth.

“The rate of change is not constant, however; it fluctuates over the years. Indeed, sometimes it does not slow down at all.”

Any change in mass distribution will contribute to a change in rotation rate because angular momentum will be conserved, but a really big term in all of this is the tidal braking from our interaction with the moon. The other contributions add noise to this, which is why the rotation speed can level off or even increase temporarily.

But since moment of inertia depends on R^2, changes in the core must involve a lot more mass relative to changes on the surface of the earth (from weather patterns and water location, for example) to contribute.

 

I had linked to an article about the problems with leap seconds some months ago, and the author came and gave a talk at the Observatory this past fall. Hearing details of some of the potential problems was interesting — the issue is that programmers generally don’t think about leap seconds, so how a system will respond is dicey, and as more and more systems rely on automation the odds of a dangerous failure increases.

There are systems that simply shut down at leap-second insertion time rather than deal with the unknown response of the computer code. But leap seconds are inserted at midnight UTC. Most of Europe is partying, without much business going on, or planes in the air. But it’s 4 PM in California, and in the morning in Asia. There’s potential for some serious complications.

The bottom line is that most people don’t care about leap seconds. Dropping them will impact astronomers, and mildly offend our sensibilities when noon on the solstices does not have the sun line up overhead — assuming you are at a longitude where this currently happens. But that’s just it: most of us aren’t. We accept time zones as a compromise between precise astronomical time and coordination and scheduling of our lives. It won’t surprise me if leap seconds are deemed more trouble than they are worth.

4 thoughts on “Taking a Non-Leap of Faith?

  1. Anthropogenic GLOBAL SLOWING! Save Our Children! First, impose a Temporal Tax on Everything to finance studies. Then, temporal credits. Countries with few clocks like Zambia that are not slowing the Earth’s rotation by overusage of time will be empowered to sell temporal credits to abusers like the US wherein every home has at least a dozen timepieces, every car, every phone… and multiple egg timers. The First World must pay for the time is is stealing from the deserving. Life expectancies must be compassionately reallocated. Head Start programs must be $trillion financed for time-tolerated minorities.

    All timers must be licensed, then inspected and certified each business quarter for nominal fees tied to accuracy, providing employment. Ownership will be preceded by a Bureau of Alternate Temporal Forensics background check. Homeland Severity will vigorously confiscate all attempts to smuggle time from the United States of America, including mandatory enhanced cavity inspections of the elderly.

    War on Stateless International Temporal Terror II – Uprisings, Wasitt II U! You had better not be late to your time audit or you wll be fined. If you are not late, you will be arrested and charged with felony temporalism. Gorilla glass hourglasses running with micron-diameter miniballs of AlMgB14/TiB2 composite, coefficient of friction of 0.02 (0.05 for Teflon) are exempt given the trickle down theory of just in time wealth.

    If we are not diligent, heinous, and selective in in our enforcement the Northern Hemisphere will slow as the Southern Hemisphere accelerates, ripping the Earth a new one. Time is a privilege not a right. All your seconds are belong to us!

  2. Bearing in mind that the signals exchanged between satellite and satnav travel at the speed of light, if one element is a full second out of step with the other the result would be an error of hundreds of miles. Haven’t bothered to do the calculation – it’s probably thousands.

Comments are closed.