In January 2012, international delegates met at the headquarters of the International Telecommunications Union (ITU) in Geneva. His mission was to discuss whether we should change a basic foundation of our culture, our biology, and our evolution. Should our days and nights continue to be regulated by sunrise and sunset, as they have been since the first critters found themselves stranded on the shores of the primordial sea? Or should an increasingly arbitrary definition of the basic unit of time, measured by a soulless atomic clock, govern the measurement of our lives?

Atomic clocks were first demonstrated in 1949, but by the mid-1960s they had advanced to the point where they were the most accurate clocks in the world; more precise than the one that had been the master clock by which all other clocks and clocks on the planet had been regulated up to that point: the rotating Earth itself. Indeed, compared to the exquisitely timed beat of the atomic clock, the Earth was revealed to be a rather poor timekeeper. So, in 1967, one second of time was redefined as 9,192,631,770 vibrations of the cesium-133 atom, instead of 86,400 parts of the mean solar day.

In 1972, when atomic clocks assumed the role of the world’s master timekeepers, time was originally set like any other clock to match the movement of the sun as it rose and set. Man’s most advanced technical triumph in keeping track of time was built on the humble sundial, surely man’s oldest method of keeping track of the day. Since that day, atomic clocks have become vital in regulating the increasingly complex technology that forms the infrastructure of our lives. Internet web servers and email providers must work in synchronized harmony. GPS satellites know the correct time to within a billionth of a second, so they can keep us within a few meters of where we actually are. The mobile phone networks that carry our text messages and digitized voices also need to know the time with great precision.

But there’s a problem. The rotational speed of the earth is gradually slowing down. The main reason for this is the moon. As the moon revolves around the earth, it pulls in the waters of the world’s great oceans and moves them around, creating the tides we see in harbors and along the coast. But splashing all that water and dragging it across the ocean floor generates heat due to friction. The heat produced eventually radiates out into space, but the energy to create that heat has to come from somewhere. And that somewhere is the rotational energy of the earth, the potential energy stored in the planet by virtue of its rotation like a gyroscope. Another consequence of this tidal friction is that the Earth’s rotational energy is transferred to the Moon’s orbital energy, thus gradually moving the Moon away from the Earth. One hundred million years ago, at the time of the dinosaurs, the day was about 4 minutes shorter than it is now. Ten thousand years ago, in the days of stone age man, the day was a quarter of a second shorter than it is now. In 1967, the day marked by atomic clocks was 0.006 seconds shorter than it is now.

Now.006 of a second doesn’t sound like much. But if the day measured by atomic clocks is six milliseconds shorter than the day measured by sunrise and sunset, the difference between the atomic clocks and the sun as it crosses the sky soon becomes significant. The lapse of approximately six months will result in the two ‘clocks’ drifting apart for a second. Since 1972 the solution has effectively been to ‘stop the atomic clock’ for a second to allow the earth to catch up, and for the last forty years the insertion of these ‘leap seconds’ has meant that the time recorded by clocks atomic has been kept in sync with the rotation of the earth within one second.

But inserting these leap seconds into all of the world’s atomic clocks, all at the same time, creates the potential for mischief to ensue. A bug in a program somewhere could mean that the clock that (say) regulates stock trading in a major financial center could hit a snag and confuse electronic financial transactions around the world. To avoid the possibility of this happening, there was a proposal at the ITU meeting in Geneva to do away with leap seconds and let our clock time deviate from ‘natural’ time as shown on a sundial.

But the obvious flaw in this argument is that if we eliminate leap seconds, there would eventually come a time when the Earth would be so far behind the time regulated by atomic clocks that we would be having lunch as the sun rose. That’s clearly nonsense, so there would have to be some kind of reckoning at some point in the future to bring atomic clocks back in line with the natural day experienced by sunrise and sunset. Atomic clock time would eventually have to realign with the sundial.

There was a counterproposal at the ITU meeting that it is better to leave things as they are and continue to insert a leap second once or twice a year than to wait several hundred years to insert a leap hour. The technology is now ready to deal with the problem by inserting leap seconds. By waiting several hundred years to insert a leap hour, we would be assuming untested technology in atomic clocks not yet built, and that has far more potential to cause harm than continuing with the current system.

At the International Telecommunications Union meeting, the “Let’s prevent a problem before it happens” argument was led by the United States, followed by France and Germany. But they did not prevail over the “If it ain’t broke, don’t fix it” case led by the UK, with China and Canada among countries taking a similar view. Each argument has its merits, but there was no clear case that led the vast majority of undecided countries in favor of one or the other. In the end, it was decided to leave things as they are and wait to see if a convincing case for the change emerged at some point in the future.

So for now, the humble sundial in the garden will remain a good guide to when it’s time for lunch!