IU2. Committee on Data for Science and Technology (CODATA)

Report to the 2005 IUPAP General Assembly


CODATA, the Committee on Data for Science and Technology, is an interdisciplinary Scientific Committee of the International Council for Science (ICSU), which works to improve the quality, reliability, management and accessibility of data of importance to all fields of science and technology. CODATA is a resource that provides scientists and engineers with access to international data activities for increased awareness, direct cooperation and new knowledge. CODATA was established 33 years ago by ICSU to promote and encourage, on a world-wide basis, the compilation, evaluation and dissemination of reliable numerical data of importance to science and technology. Today 23 countries are members, and 14 International Scientific Unions have assigned liaison delegates.

CODATA is concerned with all types of data resulting from experimental measurements, observations and calculations in every field of science and technology, including the physical sciences, biology, geology, astronomy, engineering, environmental science, ecology and others. Particular emphasis is given to data management problems common to different disciplines and to data used outside the field in which they were generated.

The 19th International CODATA Conference, THE INFORMATION SOCIETY: NEW HORIZONS FOR SCIENCE, was held in Berlin, Germany on 7-10 November 2004. The conference had sessions on Data Archiving, Data Quality, Data Visualization, E-Learning, Environmental Informatics, Gas Hydrates, Infoscience Today, Interoperability, Knowledge Discovery, Multi-disciplinary Data Projects, Open Scientific Communications, Publication and Citation of Scientific Data, Scientific Data for Economic Development, Scientific Informatics in EurAsia, World Summit on the Information Society (WSIS). The proceedings are available at

The CODATA Task Group on Fundamental Constants periodically provides 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.

The latest such set of values, termed the 2002 CODATA recommended values, are based on all data available up to the end of 2002. The 2002 CODATA values became available on the Web at in December 2004.

The detailed and lengthy report on the 2002 adjustment of the fundamental constants has been published as "CODATA recommended values of the fundamental physical constants: 2002," Reviews of Modern Physics, Vol. 77, pp. 1-107 (2005). The report describes the criteria and procedures of the data selection and the methodology of the determination of the values of the constants.

Credit card size wallet cards that give values of a selected subset of the constants have also been published. These are available upon request from the CODATA Secretariat or from the Public Relations Office of the National Institute of Standards and Technology (NIST) by sending a request to

The Task Group held its annual meeting on 28 June 2005. This year it met at the International Bureau of Weights and Measures (BIPM) near Paris.

At the meeting it was decided that the Task Group would maintain its schedule of providing new sets of recommended values every four years. In keeping with this schedule, the next set of recommended values will be based on data available by the end of December 2006 and will be termed the 2006 CODATA recommended values. These new recommended values will be made available early in 2007.

In connection with the current considerations of the proposal to redefine the kilogram and other base units of the International System of Units (SI), the Task Group was asked by the President of the Consultative Committee on Units (CCU) of the International Committee on Weights and Measures (CIPM) to provide its point of view. Based on discussion at the June meeting, the Task Group formulated the following recommendation to the CCU.


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.

The next meeting of the Task Group is scheduled for 15 July 2006 in Torino, Italy in conjunction with the 2006 Conference on Precision Electromagnetic Measurements (CPEM).

Peter Mohr
IUPAP liaison to CODATA

Peter J. Mohr
Fundamental Constants Data Center
Precision Measurement Grants Program
National Institute of Standards and Technology
100 Bureau Drive, Stop 8401
Gaithersburg, MD 20899-8401
(301) 975-3217
(301) 975-4578 FAX


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