Researchers have constructed an atomic clock that is the most precise ever made, and it has the potential to redefine how seconds are measured. The instrument relies on the element lutetium for its timing mechanism, and it achieves accuracy to 19 decimal places — a 41% enhancement over the earlier best performer. The findings appeared Sept. 23, in the journal Nature.
The clock is a major step forward for a field that has been pushing boundaries since the 1950s. Atomic clocks have long been the backbone of timekeeping, and this new device could finally replace the standard that has defined the second for decades.
What the Clock Does
The measurement of time using atomic clocks depends on following the vibration of atoms. Lutetium-176 is the particular element whose atoms are watched as they vibrate. Each microsecond is defined by that vibration, which the clock monitors with a degree of accuracy that is remarkable.
The old standard held its accuracy to a set number of decimal places, while the new clock surpasses it by 41%. This is a significant gap in an area where small fractions of a second count for everything. The gain is not merely on paper — it alters how we gauge the very foundation of the metric system.
That difference matters because the measurement of a second is itself a foundation for much of modern life. The metric system, which governs measurements from length to mass to electrical current, rests upon the second as its primary unit of time. So even a small improvement in how seconds are measured can ripple outward into many other domains, from telecommunications to navigation to scientific research.
The Element Behind the Clock
The scientists note that the clock’s operation remains stable despite changes in its surroundings, particularly when it comes to magnetic fields and temperature. While other components need precise adjustment for their environment, lutetium-176 continues to mark time through a 5-degree shift in external temperature.
To address the effects of gravitational fields, the team created a method known as hyperfine averaging. This approach minimizes any remaining variation in timekeeping, which is essential for a device that must stay accurate over extended periods.
A Runner’s Analogy
Murray Barrett, a physicist at the National University of Singapore who took part in the study, described the task with a sports analogy. He said the goal is to ensure the runner can go the distance, and lutetium, as it happens, is a natural-born endurance athlete.
“Our job is to make sure the runner can go the distance. Lutetium, as it turns out, is a natural born endurance athlete.”
What the scientists are attempting to build is a clock that keeps going without losing its rhythm from external forces, and the analogy makes that goal clear. Lutetium looks to be the ideal candidate for such a timepiece.
The Legacy of Cesium
The history of atomic clocks stretches back to the 1960s, when scientists first built instruments that measured time using the radioactive forms of the element cesium, a silvery metal. Later, the International Bureau of Weights and Measures (BIPM) changed its definition of the second in 1968, setting it to match the radiation given off by the isotope cesium-133.
The official definition of one second is 9.19 vibrations of a cesium-133 atom. Before that, a second was set as 1/31,556,925 of the length of the solar year 1900. That atomic standard has since become the definitive measure for keeping time.
For decades now, radioactive metals beyond 1960 have been employed in the construction of atomic clocks, with ytterbium and strontium serving as notable examples. These timekeeping devices currently anchor systems including GPS, the internet and military technology.
The Metric System’s New Standard
A new atomic clock may take over as the metric system’s standard measure of time. The BIPM plans to redefine the second in 2030, using today’s atomic clock technology. For now, lutetium appears to offer the most accurate results.
A major change would follow from altering how the second is defined. The metric system rests upon the second as its primary unit of time, so any such alteration would affect all systems that depend on it. According to the researchers, the clock’s sensitivity to outside forces makes it a strong candidate for serving in this role.
Testing the Constants of Physics
A clock this exact might also help researchers learn something fundamental about the universe: whether the constants at the foundation of physics, including G, the gravitational constant, stay constant over time. Some investigators speculate that these numbers may actually shift, and a clock this precise could catch tiny changes that would otherwise go unnoticed.
“So ultra-precise clocks give us the tools to explore that,” Barrett said.
That the numbers governing the universe may not be fixed has serious consequences for how we understand its workings. A device this accurate could put that very hypothesis to the test.
The Team Behind the Research
Barrett and his team at the National University of Singapore led the research. The group consists of Arnold, K. J., Lee, M. D. K., Zhao, Q., Qin, Q., Zhang, Z., and Jayjong, N. The paper appeared in Nature on Sept. 23.
A new standard has been set for the field, thanks to a verification carried out to the 19th digit. That degree of precision is truly impressive.
What Happens Next
The work toward the BIPM’s 2030 redefinition continues, with the foundation already being built. The researchers have demonstrated what can be achieved. What remains to be seen is whether the world’s nations will take it up.
Source material: “Physicists unveil the most accurate atomic clock ever — and it could literally redefine the second,” Live Science.
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