The revision of the SI—the result of three decades of progress in metrology - IOPscience https://doi.org/10.1088/1681-7575/ab0013
“Riehle et al (2018) also proposes five principal achievements on the path to the redefinition of the second, as a tentative outline for achieving redefinition by the 28th meeting of the CGPM, which is assumed to be in 2026.”
秒の定義が近い将来変わるかもしれないのか