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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 11:42 |
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Conference: Bucharest University Faculty of Physics 2008 Meeting
Section: Electricity and Biophysics
Title:
Quo vadis SI?
Authors:
Liviu Giurgiu
Affiliation:
Faculty of Physics, University of Bucharest
E-mail
liviu.giurgiu@g.unibuc.ro
Keywords:
SI, BIPM, CGPM, A, kg, K, mole, s
Abstract:
The definition of appropriate physical quantities and their units of measurement is not given by nature. It was a considerable progress for science, teaching and trade when, in the year 1960, the many systems of units could be reduced to a single system, the well known Système International d’Unités (SI). Today, since the speed of light is defined through the definition of the metre [1], this requires to realize an derived electric unit, the ohm, as resulting only in the measurement of a length and a frequency.
The Josephson effect (JE) and the quantum Hall effect (QHE) allow the reproduction of voltage and resistance values with great precision. The reproduction of the units ampere and coulomb based on the effect of single electron tunneling (SET) is still under development [2].
At its 23th meeting in November 2007 [3], the General Conference on Weights and Measures (CGPM) adopted a recommendation on preparative steps towards redefining the kilogram, ampere, kelvin and mole so that these units could be linked to exactly known values of the some fundamental constants at the time of the 24th General Conference (2011). This paper reviews how the quantum based SI might be best developed to meet changes in requirements.
REFERENCES
1.The International System of Units (SI) , 8th edition, ed. BIPM,France, ISBN 92-822-2213-6, 2006
2.J. P. Pekola, J. J. Vartiainen, M. Möttönen, O.P. Saira, M. Meschke, and D. V. Averin, Nature Phys. 4, 120-124, 2008
3.The Resolutions adopted by the 23rd General Conference on Weights and Measures (CGPM), p.16-17, November 12 – 16, 2007
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