The International Bureau of Weights and Measures/ Bureau international des poids et mesures (BIPM) is the home of the International System of Units (SI) and the international reference time scale (UTC). Based in Saint-Cloud, it is an intergovernmental organisation with fifty-nine member states with oversight to deal with measurement standards and provide the basis for the single system of measurements for chemistry, ionising radiation, physical metrology, and coördinated universal time.

A resolution to stop adding leap seconds by 2035 has just been passed at their 27th General Conference on Weights and Measures.

Leap seconds have been periodically added to make up for the difference between exact atomic time and the Earth’s slower rotation. However, the synchronisation of atomic time and Earth time has caused problems including for software, telecommunications, and satellite navigation.

Earth’s slightly slower rotation means the two times are out of sync; to bridge the gap, leap seconds were introduced in 1972. Since then, 27 have been added, most recently in 2016.

Dr Patrizia Tavella, head of BIPM’s time department, said the decision would allow “a continuous flow of seconds without the discontinuities currently caused by irregular leap seconds”.

“The connection between UTC and the rotation of the Earth is not lost, UTC remains related to Earth,” she said, adding that “nothing will change” for the public.

From 2035, the difference between atomic and astronomical time will be allowed to grow to a larger value than one second. Negotiations will be held to determine that value and how it will be handled.

To read the Resolutions of the General Conference on Weights and Measures’s 27th meeting, click on this link.

[Image credit: BIPM]

Categories: Ephemera