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Organised by Dr Terry Quinn CBE FRS and Dr Felicitas Arias

The development of the first atomic frequency standard by Louis Essen at the National Physical Laboratory in the 1950s is at the origin of the adoption of the atomic definition of the SI second by the 13th General Conference on Weights and Measures in 1967 and the consequent adoption of the atomic time scale today known as International Atomic Time (TAI).

After the short reign of ephemeris time as the world’s reference time scale from 1954 until 1967, Coordinated Universal Time (UTC), which is TAI synchronized to the rotation of the Earth by means of leap seconds, appeared at the time as the best compromise for satisfying the requests of all users and was adopted in 1972.

Forty years after the adoption of the definition of Coordinated Universal Time at the International Telecommunication Union (ITU), we are close to the moment of making a decision on whether or not to decouple UTC from its tight link to the rotation of the Earth embodied in UT1.  It has been a ten-year process of discussion, mainly at the ITU with the input of the International Astronomical Union, the BIPM and the Consultative Committee for Time and Frequency and other organizations.  The majority opinion support the change based on developers and users of systems that need time synchronization to a stable and continuous reference timescale; others insist on the necessity of keeping the leap-second strategy for serving some applications or just for tradition. It is our hope that, as happened in the seventies, the most appropriate definition to serve all modern applications will be adopted with the consensus of the different sectors.

The meeting brings together all the principal players involved in the present discussions on how best to meet the needs of all users of time scales.

Download the programme here (PDF).

Biographies and audio recordings are available below.