For decades, atomic clocks have been the gold standard for measuring time. Now two independent research teams have built something that leaves them in the shade: the world's first nuclear clocks.
These new timekeepers, developed by groups in the United States and Europe, use the nucleus of an atom rather than its electrons to keep time. The result is a clock that could eventually be more stable and more precise than any atomic clock ever made.
A clock that ticks inside the atom's core
Atomic clocks work by measuring the energy jumps of electrons orbiting an atom. Nuclear clocks go deeper. They measure energy transitions inside the nucleus itself, a region far less affected by outside disturbances like magnetic fields or temperature changes.
The key ingredient for these clocks is a rare isotope called thorium-229. Its nucleus has a unique property: it can be excited by ultraviolet laser light, making it possible to trigger and measure a nuclear transition. Scientists have chased this capability for years.
Both teams used thorium-229 atoms embedded in a crystal. They hit the nuclei with a precise ultraviolet laser and counted the resulting ticks. The experiments took place in separate labs, one in the United States and one in Europe, and both succeeded around the same time.
Why local researchers and the world are paying attention
For physicists, this is a milestone decades in the making. The idea of a nuclear clock was first proposed in the 1970s, but the technology to realize it only came together recently. Researchers in the field have called the breakthrough a long awaited achievement.
The new clocks are not yet ready to replace atomic clocks in everyday use. They are large, delicate laboratory setups. But the potential is enormous. Nuclear clocks could improve GPS accuracy, test fundamental physics theories, and even detect tiny changes in fundamental constants over time.
Local scientists involved in the projects expressed excitement about what the clocks might reveal. The ability to measure time at this level could open windows into dark matter or other phenomena that current instruments cannot detect.
A new era for timekeeping
The arrival of nuclear clocks does not mean atomic clocks are obsolete. But it does mark a shift. For the first time, timekeeping has moved from the electron shell to the nucleus. The precision gap between the two types of clocks is still being measured, but early results suggest nuclear clocks could eventually outperform their atomic predecessors by a significant margin.
Both research teams published their results in scientific journals, and other labs are already working to build their own versions. The race to refine and miniaturize nuclear clocks has begun.
