Experts have voted to stop adding extra seconds to clock time – the outcome favours big tech

On June 30 2015 at 23:59:59 UTC (19:59:59 EDT), artist Sara Morawetz was standing in the middle of New York’s Times Square with a pair of cymbals. As the clock ticked to the next second, she struck the cymbals together.

This simple performance, titled 61/60, sought to highlight the strange blip of time where the clock read 23:59:60 UTC (Coordinated Universal Time), instead of 00:00:00 UTC.

Since 1972, extra seconds, known as leap seconds, have been added to clock time whenever our slightly wobbly Earth falls out of sync with atomic clocks (which run more consistently). A total of 27 leap seconds have been added in those five decades.

They are therefore important in fields like astronomy because they keep the link between clock time and solar time – which is based on our planet’s movement.

But on Thursday 15 October, delegates at the General Conference on Weights and Measures (CGPM) in Versailles, France, voted to abolish them, starting from 2027.

Their loss might seem trivial to some people. But in the field of precision timekeeping, leap seconds are highly controversial. They have the potential to affect everything from financial trading, telecommunications and the energy sector to data centres and the legal system.

In fact, they have threatened to interrupt any sector that requires accurate timing. For example, data centres use time synchronisation to ensure distributed servers work together effectively. In finance, time stamps ensure orders are carried out accurately and provide an audit trail for complying with regulations.

When a leap second was added in 2012, it caused websites such as Reddit and Linkedin to crash and Qantas airline flights to be delayed.

In the reporting on today’s decision, these risks to computing systems are often described as the main reason for the end of leap seconds, but in fact the risk was to the single globally accepted standard of time.

Big tech concerns

In 2008, when a leap second was due to be added to the clock on December 31, Google was unwilling to risk adding it in a single step. Instead, the tech giant’s time servers deviated from UTC for a period of 20 hours, “smearing” the extra second across this time period in increments that were so small their systems did not notice them.

Effectively, Google determined that UTC was not suitable for its needs and invented its own form of clock time in response. Increasingly, other corporations adopted their own workarounds, raising concerns about the ability of UTC to retain its position as the pre-eminent determination of time.

As a result, conversations within the international bodies responsible for standardisation have, in recent years, focused on the ways that the current model of clock time no longer works as a standard for all.

As Mario Maniewicz, director of the International Telecommunications Union (ITU-R), has argued, clock time needs to be updated so that it can meet the needs of 21st century users.

At the 2022 CGPM, it had already been agreed by delegates that, by 2035, UTC would effectively be free of leap seconds. However, recent predictions of future changes in Earth’s rotation raised the possibility of the first negative leap second, where a second is subtracted rather than added to the clock.

Alarm over the unprecedented impact this situation could have led to it being likened to a new Y2K event. The increased risk of losing users of UTC to forms of timekeeping that do not require leap second adjustments led to the proposal agreed at Versailles, namely to bring forward the end of leap seconds to May 20 2027.

Meeting needs

UTC has thus been redefined so that it can be reasserted as a shared standard, free of the controversy it once held for many economic activities.

As I’ve argued previously, the leap second debate has shown that our usual ideas of clocks as abstract, mathematical and objective are incorrect. These ideas do not take into account the way that clocks are designed tools that are reformulated when needs shift.

Global computing and tech companies now have the time they need for their systems to work more smoothly. But astronomers will no longer be able to use UTC as a broad proxy for the Earth’s rotation as they did before. The proposal brought before the CGPM mentions this, but more or less says they will need to look elsewhere for their requirements.

The implication of the decision seems to be that computing needs have been placed above the requirements of other sectors. But the larger question raised by today’s decision at the CGPM is one the broader public has rarely asked, namely what other “user needs” are going unmet by the assumption that all human activities can be coordinated by a single standardised clock time? Astronomy provides one example of this, but our own experiences of pressure and anxiety around time suggest there are others.

Can we reinvent time?

There is a strange kind of audacity in even considering the idea of changing clock time to suit our own needs. Google was able to do it in part because it is big enough to do so.

But think about the common habit of running our clocks slightly fast to help with getting to meetings on time. This is done so often that Apple had to introduce an official feature to its smart watch allowing people to set it to the wrong time on purpose.

Public clocks do this occasionally too, such as the turret clock on the Balmoral Hotel in Edinburgh. Since 1902, the clock has run three minutes fast to help travellers arrive on time at the nearby Waverley train station. There are also clocks that let you track time outside of the UTC standard that was redefined today.

Designer Scott Thrift has built a clock called The Present which features a single hand that moves with the changing seasons across a full year. Thrift described The Present as “no hours, no minutes, no numbers. Only the bigger picture”. US scientists working on Mars missions created their own watches to track Martian days (called sols) which run longer than Earth days.

Many people may think of clock time as immovable and inevitable. As the latest vote shows, the “shape” of the clock remains up for debate. Currently, if you are big enough it will bend to your needs. We need to decide if we are happy to just leave the big players to it.

Michelle Bastian does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.