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Two clocks, built separately, agreed to 18 decimal places

Qurexa Editorial Team24 September 20266 min read 0 0
Two clocks, built separately, agreed to 18 decimal places

What happened

A team in Singapore has built what is now the most accurate clock ever made. The clock works by using a single ion of lutetium, a silvery metal element, held almost perfectly still in an electric trap and cooled with lasers. The atom absorbs light at one exact frequency. Count the waves of that light and you have a tick. Count enough ticks and you have a second. The researchers at the Centre for Quantum Technologies, part of the National University of Singapore, reported an uncertainty of 1 part in 10 to the power of 19. Written out, that is roughly one part in ten billion billion. Here is the test that matters most. The team did not build one clock. They built two, independently, and then compared them over 200 hours. The two clocks agreed with each other to within 5.7 parts in 10 to the power of 19. That cross-check is the hard part. A single clock can be very precise and still be wrong in a way nobody notices. Two clocks built separately, agreeing that closely, is much stronger evidence. The work was published in the journal Nature and reported on 23 September 2026.

Why this matters

It is easy to read this and think: who needs a clock that good? Nobody is late by a billionth of a second. But clocks are not really about being on time. They are the foundation of measurement. The metre is officially defined using the speed of light and the second. Position, distance and navigation all lean on timing. The most familiar example is satellite navigation. GPS and its European equivalent, Galileo, work by comparing the tiny time differences between signals from several satellites. Improve the clocks and you improve the positioning. That feeds into aviation, shipping, farm machinery, emergency response and the phone in your pocket. There is a stranger use too. Einstein showed that time runs very slightly faster the further you are from the centre of the Earth. A clock this precise can detect that difference over a height change of about a centimetre. That turns a clock into a gravity sensor. Networks of such clocks could track how water moves underground, how magma shifts beneath a volcano, or how sea level is really changing. And there is the second itself. The official definition of the second has been based on caesium since 1967. Optical clocks like this one are now far better, and the international community is working towards a redefinition, possibly around 2030.

What the evidence actually says

The paper's real contribution is not just the number. It is why lutetium was chosen. Most precision clocks are fragile. They are thrown off by heat radiating from the walls of the apparatus, by stray electric and magnetic fields, and by small vibrations. Correcting for all of that is painstaking work, and every correction adds uncertainty. Lutetium is unusually insensitive to these effects. Murray Barrett, who leads the team, put the temperature point vividly: the clock would stay stable even if you moved it from Death Valley, the hottest place recorded on Earth, to the Antarctic plateau, the coldest. That robustness is the practical story. Plenty of laboratory clocks post impressive numbers in ideal conditions. A clock that does not care much about its surroundings is a clock you could eventually put on a ship, in a satellite, or at the bottom of a mine shaft. It is worth being clear about the limits. This is a laboratory instrument, not a product. It takes a room, a team of specialists and a great deal of equipment. Making it portable is a separate and very difficult engineering problem. And a single result, however careful, is normally confirmed by other laboratories before the international measurement community acts on it. That process takes years, by design.

Practical advice

There is nothing here to buy or do. But there is something worth understanding, because this kind of story gets reported badly. When you see a claim like 'this clock would not lose a second in the age of the universe', treat it as a way of picturing the number rather than a literal promise. Nobody has run the clock for that long. The detail to look for in any precision measurement story is whether the result was checked against something independent. Here it was, with a second clock built separately. That is the mark of careful work, and it is a good habit to look for it in any field, including health research. If you are curious about where this shows up in daily life, the UK's national timekeeping is maintained by the National Physical Laboratory in Teddington, and NPL time is what your phone, your bank's transaction records and the electricity grid ultimately sync to. And if you have a child interested in science, this is a good example of a field where patience and carefulness matter more than flashes of genius. The team spent years reducing sources of error one at a time.

What to know

Researchers at the Centre for Quantum Technologies in Singapore have built a lutetium-based optical atomic clock with an uncertainty of about 1 part in 10 to the power of 19, the lowest reported for any optical clock. Two independently built versions agreed to within 5.7 parts in 10 to the power of 19 over 200 hours. The interesting part is not only the precision but the stability: lutetium is far less bothered by temperature and stray fields than most alternatives, which is what would make a clock like this usable outside a laboratory one day. The likely long-term consequences are better satellite navigation, clocks used as gravity sensors to monitor water and geology, and eventually a new international definition of the second, perhaps around 2030. Sources: Nature, 'Lutetium optical clock with 10^-19 systematic uncertainty', 2026, https://www.nature.com/nature ; Phys.org, 'Scientists build world's most accurate atomic clock', 23 September 2026, https://phys.org/news/2026-09-scientists-world-accurate-atomic-clock.html ; National Physical Laboratory, 'Time and frequency', https://www.npl.co.uk/time-frequency This article is for general information and does not replace advice from a doctor, pharmacist or other qualified healthcare professional.

#atomic clock#quantum physics#measurement#Nature#GPS#science

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