Researchers at the National University of Singapore have built an atomic clock based on the element lutetium that they say is the most accurate timepiece ever demonstrated. According to ScienceAlert, the device measures a second with an uncertainty below a ten-billion-billionth of a second — roughly four times better than any previously recorded result. The team's work was published in the journal Nature.
Put another way, the clock would be off by less than a single second if it ran for about 300 billion years.
"I am confident that what we have now is the most accurate clock in the world," physicist Murray Barrett said, per ScienceAlert. "In the future, I just don't see how this clock can be beat."
Why it matters
Ordinary watches and phones keep time well enough for daily life, but atomic clocks operate on an entirely different scale of precision. They work by counting the "ticks" of light waves or microwave signals produced when electrons shift between energy levels. Because each element swaps levels at a known frequency, a single atom can anchor the rhythm of the ticks.
That precision is not an end in itself. Ultra-accurate clocks underpin some of the most fundamental large-scale investigations in physics, including efforts to measure how gravity varies across the Earth. ScienceAlert notes that these instruments serve as far more than a reference point for the time of day.
A decade of work on an unusual element
Cesium has traditionally served as the reference element for atomic clocks, though researchers have tested others in recent years, including strontium. Elements that oscillate faster than cesium produce more ticks per second.
The Singapore team has spent about ten years exploring lutetium for timekeeping and, according to ScienceAlert, remains the only group to have realized its potential.
What sets lutetium apart is its stability. Its atomic structure shields it unusually well from heat, magnetism, and motion — the kinds of disturbances that would otherwise disrupt the shifting of electron energy states.
"The good properties mean that high accuracy can be achieved even in a wide range of environments," Barrett said.
He added that the lutetium clock would hold steady even if it were moved from Death Valley, the hottest place recorded on Earth, to the cold of the Antarctic plateau.
Two clocks, 200 hours, no measurable difference
To check their results, the researchers constructed a second lutetium clock and compared the two against each other, adjusting for Einstein's theory of general relativity since the units were not in precisely the same location.
Over 200 hours of measurements spread across 12 days, the gap between the two devices was so small that it amounted to effectively zero.
"There is a humorous saying that 'a man with a watch knows what time it is, a man with two watches is never sure'," physicist Kyle Arnold said, according to ScienceAlert. "It basically tells you that the only way to test the accuracy of a standard is to compare clocks and demonstrate reproducibility."
Shrinking the lab
The current clock occupies an entire laboratory, and the team's next goal is to make it smaller and transportable. A movable version could be tested for accuracy in more locations and put to practical use — monitoring magma underground, for instance.
Lutetium again offers an advantage here. It relies on off-the-shelf lasers that do not demand excessive space, and it operates at room temperature, so no bulky cooling equipment is required.
"The next step is to take the lab-scale clock and miniaturize it into a transportable system," physicist Michael Lee said.
ScienceAlert reports that the article was fact-checked by Rachel Garner and edited by Fiona MacDonald.
The coming years will show whether lutetium clocks can be shrunk to portable size and whether any rival element can match the stability the Singapore team has demonstrated.
