Korean Scientists: "Redefining International Standard Time 100 Times More Accurate with Our Own Hands"

Five Research Institutes Sign Memorandum of Understanding for Spatiotemporal Convergence Research Collaboration

Cesium atomic clock. Photo.

[Asia Economy Reporter Kim Bong-su] Korean scientists are joining forces to measure international standard time with 100 times greater accuracy than before.

On the afternoon of the 24th, five national research institutions?the National Geographic Information Institute, Korea Advanced Institute of Science and Technology (KAIST), Korea Institute of Science and Technology Information (KISTI), Korea Astronomy and Space Science Institute (KASI), and Korea Research Institute of Standards and Science (KRISS)?signed a memorandum of understanding at the main office of KASI in the Daedeok Research and Development Special Zone in Daejeon for “Space-Time (視空間) Convergence Research Cooperation.”

They agreed to jointly utilize major research equipment owned by each institution, conduct research on extreme precision measurement of space-time, produce, transmit, analyze, and utilize research data for international joint research, and discover and promote convergence cooperation areas of mutual interest.

In particular, through this cooperation, they plan to make significant contributions to the determination of Coordinated Universal Time (UTC), the international standard time, and the redefinition of the “second.” UTC is the international standard time created by combining time information from about 450 atomic clocks worldwide. While the International System of Units (SI) redefined the ampere (A), kelvin (K), kilogram (kg), and mole (mol) in 2019, the time unit “second,” which has the highest accuracy, has not been redefined for over half a century since its definition in 1967 due to technical limitations.

Specifically, the unit of time “second” is managed by mutually comparing the unique frequency measurements of cesium atoms generated from hundreds of commercial atomic clocks and cesium atomic clocks held by about 80 institutions worldwide using satellites. Recently, with the development of optical clocks that are about 100 times more accurate than existing cesium atomic clocks, research related to the redefinition of the “second” has become a hot topic in the global scientific community. Cesium atomic clocks determine the “second” by measuring the unique frequency of cesium atoms (about 9.1 billion vibrations per second), but optical clocks are next-generation atomic clocks that can determine the “second” with 100 times greater precision (measuring up to 18 decimal places) than cesium atomic clocks (which measure up to 16 decimal places).

For the redefinition of the “second,” it is necessary to compare the frequencies of optical clocks developed by institutions worldwide, and it is expected that precise time comparison will be possible by utilizing broadband Very Long Baseline Interferometry (VLBI). Current VLBI technology boasts space-time precision capable of observing black holes about 50 million light-years away, but it has limitations in that analyzing measurement results requires significant time and effort. To mutually compare optical clock time information located on different continents using broadband VLBI, technology to generate noise-free high-frequency signals from optical clock signals is required. A transmission network infrastructure capable of rapidly transmitting large volumes of data with high stability is also essential.

These five research institutions plan to accelerate research on redefining international standard time through convergence research cooperation. Based on the National Science and Technology Research Network (KREONET) operated by KISTI, they will conduct convergence research to overcome the world’s first limits of space-time measurement precision by utilizing the ytterbium optical clock developed by KRISS, KAIST’s optical frequency comb technology, KASI’s Korean VLBI Network (KVN), and the radio telescope of the Space Geodesy Observation Center of the National Geographic Information Institute combined in VLBI.

Previously, in April 2020, they successfully completed the preliminary convergence research project “Preliminary Study to Overcome the Limits of Space-Time Measurement Precision Based on Broadband VLBI” under the National Research Council of Science and Technology. In December, they plan to conduct intercontinental time comparison demonstration observations using VLBI together with Italy’s National Institute of Metrological Research (INRiM) and National Institute for Astrophysics (INAF).

An official from KASI said, “Led by Korea, we will conduct world-class research on intercontinental optical clock time comparison technology and establish a foundation for leading the hyper-connected era through ultra-precise space-time information transmission and synchronization in the Fourth Industrial Revolution era, as well as creating new scientific research achievements.”

This content was produced with the assistance of AI translation services.