The recently published cover story of Nature magazine brings a new breakthrough: an international team led by the Joint Institute of Experimental Astrophysics (JILA), jointly established by the National Institute of Standards and Technology and the University of Colorado Boulder, has successfully demonstrated the key technology of nuclear clocks. When the laser is irradiated into the gas jet and interacts with the remaining gas in the vacuum chamber, it leaves a white line, which helps to accurately measure the energy required to excite the thorium-229 atomic nucleus. This top research team used a specially designed ultraviolet laser to accurately measure the frequency of energy transitions in thorium atomic nuclei embedded in solid crystals. At the same time, with the help of an optical frequency comb (similar to an extremely precise optical ruler), the number of ultraviolet wave periods that produce the energy transition was calculated. This experiment covers all key technologies of nuclear clocks, laying a solid foundation for the further development of nuclear clocks. The emergence of nuclear clocks is expected to bring about many significant changes. This is because atomic clocks measure time by adjusting the laser frequency to make electrons jump between energy levels, while nuclear clocks only utilize energy jumps in the tiny region of the atomic center - the nucleus. The influence of external interference on atomic nuclei is much smaller than that of electrons in atomic clocks, and the laser frequency required to cause energy transitions in atomic nuclei is much higher than in atomic clocks. This means that there are more wave periods per second, directly related to more "ticking" times per second, thus enabling more accurate timing. However, most atomic nuclei require coherent X-ray (high-frequency light) impacts to achieve energy transitions, far exceeding the energy generated by existing technologies. For this reason, scientists have focused their attention on thorium-229. The nuclear energy transition of this type of atom is smaller than any other known atom, and only requires excitation by ultraviolet light (energy lower than X-rays). In the new study, the JILA team utilized the thorium-229 nuclear transition to produce the ticking sound of a clock. Laser generates precise energy jumps between various quantum states of the atomic nucleus, and frequency combs can directly measure these 'ticking sounds'. The accuracy of this work is one million times higher than previous wavelength based measurements. The team also established the first direct frequency link between nuclear transitions and atomic clocks. This direct frequency link and improvement in accuracy are undoubtedly a key step in developing nuclear clocks and integrating them with existing timing systems. Nuclear clocks are more accurate than atomic clocks. For ordinary people, this means more accurate navigation system, faster Internet speed, more reliable network connection and more secure digital communication. Not only that, nuclear clocks also have great potential in improving the fundamental theory of the universe, helping to detect dark matter, verify whether natural constants are constant, and even verify particle physics theories without the need for large particle accelerator facilities. This research has achieved unprecedented results. Although it is currently not a functioning nuclear clock, it is undoubtedly the most crucial step towards manufacturing portable and highly stable nuclear clocks. (New Society)