International Council for Science : Committee on Data for Science and Technology

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C O D A T A

Fundamental Physical Constants
established in 1969

http://physics.nist.gov/constants

Approved by the CODATA 23^rd General Assembly in Montréal 2002
Renewal approved by the CODATA General Assembly, Berlin 2004
Renewal approved by the CODATA 25th General Assembly, Beijing 2006

The purpose of the CODATA Task Group on Fundamental Constants is to periodically provide the scientific and technological communities with a self-consistent set of internationally recommended values of the basic constants and conversion factors of physics and chemistry based on all of the relevant data available at a given point in time.

Summary of Recent Activities

The 2002 CODATA adjustment of the values of the fundamental constants was completed in December 2003, and the results were made available on the Web at http://physics.nist.gov/constants on 9 December 2003. A detailed article on the data selection and methodology of the adjustment, done under the auspices of the Task Group, was published as: CODATA Recommended Values of the Fundamental Physical Constants: 2002, by P. J. Mohr and B. N. Taylor, Reviews of Modern Physics Vol. 77, No. 1, pp 1-107 (2005).

Wallet cards with values of some of the 2002 CODATA recommended values of the constants were published in April 2005.

Other activity is the ongoing survey of publications for new information relevant to the next adjustment of the values of the constants and the analysis of that information to determine its influence on the values of the constants. Review of this work is the main subject of meetings of the Task Group.

The annual meeting of the Task Group was held on 28 June 2005 at the Bureau international des poids et mesures, Sèvres, France. The next meeting of the Task Group is scheduled to be held on 15 July 2006 in conjunction with the Conference of Precision Electromagnetic Measurements (CPEM) in Torino, Italy.

At the Task Group meeting in June, the members, at the request of the President of the Consultative Committee on Units (CCU) of the International Conference on Weights and Measures (CIPM), reached a consensus on recommended changes to the International System of Units (SI). The recommendation submitted to the CCU follows:

Recommendation to the Consultative Committee on Units
from
The CODATA Task Group on Fundamental Constants
on the
Redefinition of SI Base Units
(28 June 2005)

The CODATA Task Group

Considering

• the importance of the fundamental constants to the scientific community because of their role in relating different branches of pure and applied science,

• the importance of defining the base units of the SI in terms of invariant physical quantities, and

• the significant reduction in uncertainty associated with the values of many fundamental constants that would occur if the Planck constant, the elementary charge, and the Boltzmann constant were to have exact values,

recommends to the CCU

• that the kilogram be redefined in terms of a fixed value of the Planck constant,

• that the ampere be redefined in terms of a fixed value of the elementary charge,

• that the kelvin be redefined in terms of a fixed value of the Boltzmann constant,

• that these changes be implemented at the same time as soon as conveniently possible, and

• that the values chosen for these constants be the CODATA recommended values at the time,

and also recommends that consideration be given to redefining at the same time the mole in terms of a fixed value of the Avogadro constant.

These recommendations were accepted by the CCU, together with input from other Consultative Committees of the CIPM, and recommendations similar to those above were passed on by the CCU to the CIPM for its consideration. The conclusion of the CIPM was that these changes to the SI could be implemented in 2011, if there were no problems at that time that would prevent it.

Future Activities

As already mentioned, the results of the 2002 least-squares adjustment of the fundamental constants has been published in the Reviews of Modern Physics. Wallet cards with values of the constants have been printed and many have been distributed. A chart with many of the 2002 recommended values of the constants has been prepared and will be available on the Web along with the complete set of values at http://physics.nist.gov/constants.

It is recognized that, because the fundamental physical constants of nature are the links in the chain that binds all of science and technology together, an internationally accepted set of recommended or “best” values of the constants and conversion factors for energy equivalents must be made available periodically for the use of the scientific and technical communities. Over the years, the CODATA recommended values have been widely accepted by the scientific and technical communities as the “official” values, thereby providing a consistency of the treatment of data that relies on the values of the constants. It is important that the work of the Task Group continues in order to monitor the relevant research and data production and provide updates with new values of the constants when necessary. CODATA is recognized as the authoritative body to recommended values of the fundamental physical constants, and it should continue to provide this service to the scientific and technical communities. Further, the recommendations of the Task Group to the CCU have contributed to their recommendation to the CIPM that is likely to change the nature of the International System of Units in a significant way. This change will also have the effect of making many of the fundamental constants significantly more accurate and in most cases, the energy conversion factors will become exact.

Beyond the 2002 recommended values, work is in progress on the next adjustment and production of recommended values of the constants and conversion factors for energy equivalents. The Task Group will monitor closely the new data that becomes available relevant to the fundamental constants and, when warranted, issue a new set of recommended values. It is anticipated that a new recommended set of constants will be issued early in 2007 based on data available and work done up to the end of 2006. This is in keeping with the modern and highly beneficial trend towards making new information immediately and widely available, especially on the World Wide Web, and the Task Group's decision to issue a new set of recommended values no less than every four years and possibly as soon as two years after the issuance of the previous values, if justified by the newly available data.

Chair

Dr. Barry M. Wood
Institute for National Measurement Standards
National Research Council
Bldg. M-36, Rm. 26
Montreal Rd.
Ottawa K1A OR6
CANADA
Telephone: +1 613 990 9225
Fax: +1 613 952 1394
Email: barry.wood@nrc-cnrc.gc.ca

Members

Dr. Franco Cabiati
Electrical Metrology Department
Istituto Elettrotecnico Nazionale
"Galileo Ferraris"
Strada della Cacce, 91
I-10135 Torino
ITALY
Telephone: +39 011 3919 435
Fax: +39 011 346 384
Email: cabiati@ien.it

Dr. Jeffery Flowers
National Physical Laboratory
Teddington, Middlesex TW11 OLW
UNITED KINGDOM (GB)
Telephone: +44 Fax: +44 20 8614 0417
Email: jeff.flowers@npl.co.uk

Dr. Kenichi Fujii
National Metrology Institute of Japan
AIST Tsukuba Central 3
1-1-1 Umezono, Tsukuba
Ibaraki 305-8563
JAPAN
Telephone: +81 298 61 4316
Fax: +81 298 50 1464
Email: fujii.kenichi@aist.go.jp

Dr. Savely G. Karshenboim
D. I. Mendeleyev Institute of Metrology
19 Moskovsky pr.
St. Petersburg 198005
RUSSIA
Telephone: +7 812 3239675
Fax: +7 812 1130114
Email: sgk@vniim.ru

Prof. Ingvar Lindgren
Department of Physics
Chalmers University of Technology
and Göteborg University
SE-412 96 Göteborg
SWEDEN
Telephone: +46 706 577432
Email: ingvar.lindgren@fy.chalmers.se

Prof. Werner Martienssen
Johann Wolfgang Goethe-Universität
Physikalisches Institut
Max von Laue Strasse 1
D-60438 Frankfurt am Main
GERMANY
Telephone: +49 69 798 47252
Email: martienssen@physik.uni-frankfurt.de

Dr. Peter J. Mohr
NIST, Bldg. 225, Rm. B161
100 Bureau Drive, Stop 8401
Gaithersburg, MD 20899-8401
USA
Telephone: +1 301 975 3217
Fax: +1 301 975 4578
Email: mohr@nist.gov

Dr. Francois Nez
Laboratoire Kastler-Brossel
UPMC case 74
tour 12, 1er etage
4 place Jussieu
F-75252 Paris CEDEX 05
FRANCE
Telephone: +33 1 44 27 72 48
Fax: +33 1 44 27 38 45
Email: nez@spectro.jussieu.fr

Dr. Terry J. Quinn CBE FRS
92 rue Brancas
92310 Sèvres
FRANCE
Telephone: +33 1 4623 0656
Email: terry.quinn@physics.org

Dr. Barry N. Taylor
NIST, Bldg. 225, Rm. B161
100 Bureau Drive, Stop 8401
Gaithersburg, MD 20899-8401
USA
Telephone: +1 301 975 4220
Fax: +1 301 975 4578
Email: barry.taylor@nist.gov

Dr. Wolfgang Wöger
Physikalisch-Technische Bundesanstalt
Postfach 3345
D-38023 Braunschweig
GERMANY
Telephone: +49 531 592 8110
Fax: +49 531 592 8106
Email: wolfgang.woeger@ptb.de

Prof. Zhang Zhonghua
Quantum Division
National Institute of Metrology
No. 18, Bei San Huan Dong Lu
Beijing 100013
PEOPLE'S REPUBLIC OF CHINA
Telephone: +10-64211631-3304
Fax: +10-64295811
Email: zzh@nim.ac.cn

Corresponding Member

Prof. Boris A. Mamyrin
Ioffe Physico-Technical Institute
Russian Academy of Sciences
26 Polytekhnischekaya
St. Petersburg 194021
RUSSIA
Telephone: +7 812 247 5849
Fax: +7 812 247 1017
Email: mamyrin@mass.ioffe.rssi.ru

Secretary

Dr. David B. Newell
NIST, Bldg. 220, Rm. B254
100 Bureau Drive, Stop 8171
Gaithersburg, MD 20899-8171
USA
Telephone: +1 301 975 4228
Fax: +1 301 975 2115
Email: dnewell@nist.gov