The Consultative Committee for Time and Frequency (CCTF) and the wider TF community is working towards a redefinition of the second, possibly in 2030. This decision has been prompted by the advent of optical frequency standards and significant improvements in the operational aspects of clocks (stability, uncertainty, robustness) and TF transfer and comparison techniques over the last ten years.

The CCTF established a task force in 2020 to oversee updates to the roadmap dedicated to the redefinition. An essential part of this global coordination involves providing the community with fundamental information about all aspects of the change. This information includes drivers, potential impact and the remaining challenges.

A publicly available webpage has been prepared with FAQs and a video of a special session devoted to this topic recorded during the European Frequency and Time Forum in Neuchatel (Switzerland) in June 2024.

We will update and add content to this webpage during the period before the redefinition. Please revisit the page regularly to stay up to date.