Abbreviation | BIPM (from French name) |
---|---|
Formation | 20 May 1875 |
Type | Intergovernmental |
Location |
|
Coordinates | 48°49′45.55″N2°13′12.64″E / 48.8293194°N 2.2201778°E |
Region served | Worldwide |
Membership | 64 member states 36 associate states (see the list) |
Official language | French and English |
Director | Martin Milton |
Website | www |
The International Bureau of Weights and Measures (French : Bureau international des poids et mesures, BIPM) is an intergovernmental organisation, through which its 59 member-states act on measurement standards in areas including chemistry, ionising radiation, physical metrology, as well as the International System of Units (SI) and Coordinated Universal Time (UTC). [1] It is based in Saint-Cloud, near Paris, France. The organisation has been referred to as IBWM (from its name in English) in older literature. [note 1]
The BIPM is overseen by the International Committee for Weights and Measures (French : Comité international des poids et mesures, CIPM), a committee of eighteen members that meet normally in two sessions per year, [3] which is in turn overseen by the General Conference on Weights and Measures (French : Conférence générale des poids et mesures, CGPM) that meets in Paris usually once every four years, consisting of delegates of the governments of the Member States [4] [5] and observers from the Associates of the CGPM. These organs are also commonly referred to by their French initialisms.
The BIPM was created on 20 May 1875, following the signing of the Metre Convention, a treaty among 17 Member States (as of November 2018 [update] there are now 59 members). [6] [ failed verification ]
It is based at the Pavillon de Breteuil in Saint-Cloud, France, a 4.35 ha (10.7-acre) site (originally 2.52 ha or 6.2 acres) [7] granted to the Bureau by the French Government in 1876. Since 1969 the site has been considered international territory, and the BIPM has all the rights and privileges accorded an intergovernmental organisation. [8] This status was further clarified by the French decree No 70-820 of 9 September 1970. [7]
The BIPM has the mandate to provide the basis for a single, coherent system of measurements throughout the world, traceable to the International System of Units (SI). This task takes many forms, from direct dissemination of units to coordination through international comparisons of national measurement standards (as in electricity and ionising radiation).[ citation needed ]
Following consultation, a draft version of the BIPM Work Programme is presented at each meeting of the General Conference for consideration with the BIPM budget. The final programme of work is determined by the CIPM in accordance with the budget agreed to by the CGPM.[ citation needed ]
Currently, the BIPM's main work includes: [9] [10]
The BIPM is one of the twelve member organisations of the International Network on Quality Infrastructure (INetQI), which promotes and implements QI activities in metrology, accreditation, standardisation and conformity assessment. [11]
The BIPM has an important role in maintaining accurate worldwide time of day. It combines, analyses, and averages the official atomic time standards of member nations around the world to create a single, official Coordinated Universal Time (UTC). [12]
Since its establishment, the directors of the BIPM have been: [13] [14]
Name | Country | Mandate | Notes |
---|---|---|---|
Gilbert Govi | Italy | 1875–1877 | |
J. Pernet | Switzerland | 1877–1879 | Acting director |
Ole Jacob Broch | Norway | 1879–1889 | |
J.-René Benoît | France | 1889–1915 | |
Charles Édouard Guillaume | Switzerland | 1915–1936 | |
Albert Pérard | France | 1936–1951 | |
Charles Volet | Switzerland | 1951–1961 | |
Jean Terrien | France | 1962–1977 | |
Pierre Giacomo | France | 1978–1988 | |
Terry J. Quinn | United Kingdom | 1988–2003 | Honorary director |
Andrew J. Wallard | United Kingdom | 2004–2010 | Honorary director |
Michael Kühne | Germany | 2011–2012 | |
Martin J. T. Milton | United Kingdom | 2013–present | |
The General Conference on Weights and Measures is the supreme authority of the International Bureau of Weights and Measures (BIPM), the intergovernmental organization established in 1875 under the terms of the Metre Convention through which member states act together on matters related to measurement science and measurement standards. The CGPM is made up of delegates of the governments of the member states and observers from the Associates of the CGPM. It elects the International Committee for Weights and Measures as the supervisory board of the BIPM to direct and supervise it.
The kilogram is the base unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially. It means 'one thousand grams'.
The litre or liter is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metres (m3). A cubic decimetre occupies a volume of 10 cm × 10 cm × 10 cm and is thus equal to one-thousandth of a cubic metre.
The metre is the base unit of length in the International System of Units (SI). Since 2019, the metre has been defined as the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second, where the second is defined by a hyperfine transition frequency of caesium.
The Metre Convention, also known as the Treaty of the Metre, is an international treaty that was signed in Paris on 20 May 1875 by representatives of 17 nations: Argentina, Austria-Hungary, Belgium, Brazil, Denmark, France, Germany, Italy, Peru, Portugal, Russia, Spain, Sweden and Norway, Switzerland, Ottoman Empire, United States of America, and Venezuela.
The International System of Units, internationally known by the abbreviation SI, is the modern form of the metric system and the world's most widely used system of measurement. Coordinated by the International Bureau of Weights and Measures it is the only system of measurement with official status in nearly every country in the world, employed in science, technology, industry, and everyday commerce.
The SI base units are the standard units of measurement defined by the International System of Units (SI) for the seven base quantities of what is now known as the International System of Quantities: they are notably a basic set from which all other SI units can be derived. The units and their physical quantities are the second for time, the metre for length or distance, the kilogram for mass, the ampere for electric current, the kelvin for thermodynamic temperature, the mole for amount of substance, and the candela for luminous intensity. The SI base units are a fundamental part of modern metrology, and thus part of the foundation of modern science and technology.
Metrology is the scientific study of measurement. It establishes a common understanding of units, crucial in linking human activities. Modern metrology has its roots in the French Revolution's political motivation to standardise units in France when a length standard taken from a natural source was proposed. This led to the creation of the decimal-based metric system in 1795, establishing a set of standards for other types of measurements. Several other countries adopted the metric system between 1795 and 1875; to ensure conformity between the countries, the Bureau International des Poids et Mesures (BIPM) was established by the Metre Convention. This has evolved into the International System of Units (SI) as a result of a resolution at the 11th General Conference on Weights and Measures (CGPM) in 1960.
Articles related to standards include:
The gray is the unit of ionizing radiation dose in the International System of Units (SI), defined as the absorption of one joule of radiation energy per kilogram of matter.
The Pavillon de Breteuil lies in the southeastern section of the Parc de Saint-Cloud in Saint-Cloud, France, to the west of Paris. It is listed in France as a historic monument. Since 1875 it has been the headquarters of the International Bureau of Weights and Measures (BIPM).
The standard acceleration of gravity or standard acceleration of free fall, often called simply standard gravity and denoted by ɡ0 or ɡn, is the nominal gravitational acceleration of an object in a vacuum near the surface of the Earth. It is a constant defined by standard as 9.80665 m/s2. This value was established by the 3rd General Conference on Weights and Measures and used to define the standard weight of an object as the product of its mass and this nominal acceleration. The acceleration of a body near the surface of the Earth is due to the combined effects of gravity and centrifugal acceleration from the rotation of the Earth ; the total is about 0.5% greater at the poles than at the Equator.
France has a unique history of units of measurement due to its radical decision to invent and adopt the metric system after the French Revolution.
The International Commission on Radiation Units and Measurements (ICRU) is a standardization body set up in 1925 by the International Congress of Radiology, originally as the X-Ray Unit Committee until 1950. Its objective "is to develop concepts, definitions and recommendations for the use of quantities and their units for ionizing radiation and its interaction with matter, in particular with respect to the biological effects induced by radiation".
The degree Celsius is the unit of temperature on the Celsius temperature scale, one of two temperature scales used in the International System of Units (SI), the other being the closely related Kelvin scale. The degree Celsius can refer to a specific point on the Celsius temperature scale or to a difference or range between two temperatures. It is named after the Swedish astronomer Anders Celsius (1701–1744), who proposed the first version of it in 1742. The unit was called centigrade in several languages for many years. In 1948, the International Committee for Weights and Measures renamed it to honor Celsius and also to remove confusion with the term for one hundredth of a gradian in some languages. Most countries use this scale.
The roentgen or röntgen is a legacy unit of measurement for the exposure of X-rays and gamma rays, and is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air . In 1928, it was adopted as the first international measurement quantity for ionizing radiation to be defined for radiation protection, as it was then the most easily replicated method of measuring air ionization by using ion chambers. It is named after the German physicist Wilhelm Röntgen, who discovered X-rays and was awarded the first Nobel Prize in Physics for the discovery.
In metrology, a standard is an object, system, or experiment that bears a defined relationship to a unit of measurement of a physical quantity. Standards are the fundamental reference for a system of weights and measures, against which all other measuring devices are compared. Historical standards for length, volume, and mass were defined by many different authorities, which resulted in confusion and inaccuracy of measurements. Modern measurements are defined in relationship to internationally standardized reference objects, which are used under carefully controlled laboratory conditions to define the units of length, mass, electrical potential, and other physical quantities.
In 2019, four of the seven SI base units specified in the International System of Quantities were redefined in terms of natural physical constants, rather than human artifacts such as the standard kilogram. Effective 20 May 2019, the 144th anniversary of the Metre Convention, the kilogram, ampere, kelvin, and mole are now defined by setting exact numerical values, when expressed in SI units, for the Planck constant, the elementary electric charge, the Boltzmann constant, and the Avogadro constant, respectively. The second, metre, and candela had previously been redefined using physical constants. The four new definitions aimed to improve the SI without changing the value of any units, ensuring continuity with existing measurements. In November 2018, the 26th General Conference on Weights and Measures (CGPM) unanimously approved these changes, which the International Committee for Weights and Measures (CIPM) had proposed earlier that year after determining that previously agreed conditions for the change had been met. These conditions were satisfied by a series of experiments that measured the constants to high accuracy relative to the old SI definitions, and were the culmination of decades of research.
The history of the metric system began during the Age of Enlightenment with measures of length and weight derived from nature, along with their decimal multiples and fractions. The system became the standard of France and Europe within half a century. Other measures with unity ratios were added, and the system went on to be adopted across the world.
The following outline is provided as an overview of and topical guide to the metric system:
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