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Adding the largest and smallest units to the SI system

Technology News |
By Nick Flaherty


The electronics industry measures the largest and smallest challenges, from exascale supercomputers to sub-nanometre structures in chips and the wavelengths of atoms to measure the second.

The International Bureau of Weights and Measures (BIPM), which determines the International System of Units (SI), is catching up with new suffixes for the largest and smallest structures.

The General Conference on Weights and Measures (CGPM) in Paris has now extended the SI units up to 1027, or ronnaFLOPS, and 1030 quettaFLOPS. This compares to exaFLOPS at 1018 and zettaFLOPS at 1021, or even yottaFLOPS at 1024.

For the tiniest structures there are now rontometres, or rm, at 10-27 and questometres, qm, at 10-30. Nanometres are 10-9 and femtometres are 10-15.

The meeting is also looking at a more accurate definition of the second, which uses these tiny sizes.

The current definition of “the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom” was set in 2018, but many National Metrology Institutes (NMIs) have surpassed the accuracy achievable by the using the current definition by a factor of up to 100. It is asking for new proposals.

The Consultative Committee for Time and Frequency (CCTF) has carried out an extensive survey amongst metrological, scientific and technology institutions, and other stakeholders, which has confirmed world-wide interest in more accurate time and frequency services enabled by a new definition of the second.

The aim is to bring proposals to the 28th meeting of the CGPM in 2026 for the choice of the preferred species of atom, or ensemble of atoms, for a new definition of the second.

www.bipm.org

 


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