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Difference between revisions of "Bureau International des Poids et Mesures 2019 The International System of Units (SI)"

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== Canonical reviewer's comments on: Bureau International des Poids et Mesures (2019) The International System of Units (SI) 9<sup>th</sup> ed. ==
__TOC__
Communicated by [[Gnaiger Erich]] 2020-07-03 — Stave I in the [[MitoFit_2020.4.v0#XX-mass_carols |'''''XX''-mass carol''']] of '''A ''X''-mass Carol'''.
=== General comment ===
:::: This SI publication is one of the most significant scientific, interdisciplinary and transdisciplinary publications of the century. Too many teachers and editors resist to making it a highly influential publication with actual impact on scientific publications, thus contributing to the current communication crisis. This does not reflect any faults of the SI authors but a lack of governance to improve scientific communication, and the limitations of the non-SI readers trapped into the International System of Impact Factors rather than guided towards implementing the International System of Units. What is the numerical value and the practical meaning of the Impact Factor of this SI publication?
=== Technical comments ===
==== Spelling ====
:::: Since 'small spelling variations occur in the language of the English speaking countries (for instance, "metre" and "meter", "litre" and "liter")' (p. 124), a decision should be taken for consistent spelling in a document. The English text of the SI brochure follows the style "metre" and "litre". It is found that in the scientific literature the spelling style "meter" and "liter" prevails even in European journals. Below are direct quotes from the SI brochure (with reference to the page number in the 9<sup>th</sup> edition), implementing corresponding changes in spelling style.
==== Quantity calculus (p. 147) ====
:::: Symbols for units are treated as mathematical entities. In expressing the value of a quantity as the product of a numerical value and a unit, both the numerical value and the unit may be treated by the ordinary rules of algebra. This procedure is described as the use of quantity calculus, or the algebra of quantities. For example, the equation ''p'' = 48 kPa may equally be written as ''p''/kPa = 48. It is common practice to write the quotient of a quantity and a unit in this way for a column heading in a table, so that the entries in the table are simply numbers.
Suggestion: ''p''/[kPa] = 48
==== Quantity symbols and unit symbols (p. 149) ====
:::: Unit symbols must not be used to provide specific information about the quantity and should never be the sole source of information on the quantity. Units are never qualified by further information about the nature of the quantity; any extra information on the nature of the quantity should be attached to the quantity symbol and not to the unit symbol.
Comment: Quantity calculus can be extended by providing specific information about the entity (''e.g.'' entity O<sub>2</sub>, not the quantity 'amount') together with the unit symbol, ''e.g.'', [mol O<sub>2</sub>] or [kJ·mol<sup>-1</sup> O<sub>2</sub>], where the entity-type is not presented in the place occupied by the unit symbol for division or multiplication, respectively.
=== No comment ===
==== Defining the unit of a quantity (p. 127) ====
:::: The value of a quantity is generally expressed as the product of a number and a unit. The unit is simply a particular example of the quantity concerned which is used as a reference, and the number is the ratio of the value of the quantity to the unit.
:::: For example, the speed of light in vacuum is a constant of nature, denoted by ''c'', whose value in SI units is given by the relation ''c'' = 299 792 458 m/s where the numerical value is 299 792 458 and the unit is m/s.
:::: For a particular quantity different units may be used. For example, the value of the speed ''v'' of a particle may be expressed as ''v'' = 25 m/s or ''v'' = 90 km/h, where meter per second and kilometer per hour are alternative units for the same value of the quantity speed.
:::: Before stating the result of a measurement, it is essential that the quantity being presented is adequately described. This may be simple, as in the case of the length of a particular steel rod, but can become more complex when higher accuracy is required and where additional parameters, such as temperature, need to be specified.
:::: When a measurement result of a quantity is reported, the '''''estimated''''' value of the measurand (the quantity to be measured), and the '''''uncertainty''''' associated with that value, are necessary. Both are expressed in the same unit.
=== Canonical comments ===
==== Definition of the SI (p. 127) ====
:::: As for any quantity, the value of a fundamental constant can be expressed as the product of a number and a unit.
:::: The definitions below specify the exact numerical value of each constant when its value is expressed in the corresponding SI unit. By fixing the exact numerical value the unit becomes defined, since the product of the numerical value and the unit has to equal the value of the constant, which is postulated to be invariant.
Comment: The terms 'numerical value' and 'number' are used as being equivalent: value = "product of a number and a unit"; value = "product of the numerical value and the unit". It should be considered to define: quantity ''Q'' = product of the '''numerical value''' of a number ''N'' and a unit ''u''<sub>''Q''</sub>. Symbols for specific quantities ''Q'' are, ''e.g.'', ''m'' and ''V'' for mass and volume, respectively. Do they represent merely the quantity ''type''? Interpret a formula such as ''m'' = 60 kg: The symbol ''m'' represents the quantity 'mass', the numerical value of the number ''N'' is 60 (''N'' = 60), the unit is ''u''<sub>''m''</sub> = kg, and the value of the quantity ''m'' is 60 kg. Just in case that these definitions appear to be acceptable, then it follows: quantity ''m'' = value of the quantity ''m''.
:::: The seven constants are chosen in such a way that any unit of the SI can be written either through a defining constant itself or through products or quotients of defining constants.
::::: '''The International System of Units, the SI, is the system of units in which'''
:::::* '''the unperturbed ground state hyperfine transition frequency of the caesium 133 atom ∆''ν''<sub>Cs</sub> is 9 192 631 770 Hz,'''
:::::* '''the speed of light in vacuum c is 299 792 458 m/s,'''
:::::* '''the Planck constant h is 6.626 070 15 × 10<sup>−34</sup> J s,'''
:::::* '''the elementary charge e is 1.602 176 634 × 10<sup>−19</sup> C x<sup>-1</sup>,'''
:::::* '''the Boltzmann constant k is 1.380 649 × 10<sup>−23</sup> J x<sup>-1</sup> K<sup>-1</sup>,'''
:::::* '''the Avogadro constant NA is 6.022 140 76 × 10<sup>23</sup> x mol<sup>−1</sup>,'''
:::::* '''the luminous efficacy of monochromatic radiation of frequency 540 × 1012 Hz, ''K''<sub>cd</sub>, is 683 lm/W,'''
:::: where the hertz, joule, coulomb, lumen, and watt, with unit symbols Hz, J, C, lm, and W, respectively, are related to the units second, meter, kilogram, ampere, kelvin, mole, and candela, with unit symbols s, m, kg, A, K, mol, and cd, respectively, according to Hz = s<sup>–1</sup>, J = kg m<sup>2</sup> s<sup>–2</sup>, C = A s, lm = cd m<sup>2</sup> m<sup>–2</sup> = cd sr, and W = kg m<sup>2</sup> s<sup>–3</sup>.
:::: The numerical values of the seven defining constants have no uncertainty.
==== Writing and printing of unit symbols and of numbers (p. 162) ====
:::: Roman (upright) type, in general lower-case, is used for symbols of units; if, however, the symbols are derived from proper names, capital roman type is used. These symbols are not followed by a full stop.
Comment: ##
:::: In numbers, the comma (French practice) or the dot (British practice) is used only to separate the integral part of numbers from the decimal part. Numbers may be divided in groups of three in order to facilitate reading; neither dots nor commas are ever inserted in the spaces between groups.
Comment: In the last sentence above, there is a confusion between '''numbers''', '''numerals''' (representing numbers, such as 4, 12, 5093.78, 6, in a specific numeral system), and '''symbols''' (or '''characters''', such as the ten characters in the decimal numeral system: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ). When a large '''number''' is expressed by a '''numeral''' as a string of several symbols, the '''symbols''' may be divided in groups of three .. 
{{Template:Base quantities and count}}
{{Template:Base quantities and count}}


== Keywords—MitoPedia ==
=== Keywords—MitoPedia ===
::::* [[Amount of substance]]
::::* [[Amount of substance]]
::::* [[Avogadro constant]]
::::* [[Avogadro constant]]

Revision as of 21:23, 3 July 2020

Publications in the MiPMap
Bureau International des Poids et Mesures (2019) The International System of Units (SI). 9th edition:117-216 ISBN 978-92-822-2272-0.

» »Open Access«

Bureau International des Poids et Mesures (2019) (SI)

Abstract: The International System of Units, the SI, has been used around the world as the preferred system of units, the basic language for science, technology, industry and trade since it was established in 1960 by a resolution at the 11th meeting of the Conférence Générale des Poids et Mesures, the CGPM (known in English as the General Conference on Weights and Measures).

Bioblast editor: Gnaiger E


Canonical reviewer's comments on: Bureau International des Poids et Mesures (2019) The International System of Units (SI) 9th ed.

Communicated by Gnaiger Erich 2020-07-03 — Stave I in the XX-mass carol of A X-mass Carol.

General comment

This SI publication is one of the most significant scientific, interdisciplinary and transdisciplinary publications of the century. Too many teachers and editors resist to making it a highly influential publication with actual impact on scientific publications, thus contributing to the current communication crisis. This does not reflect any faults of the SI authors but a lack of governance to improve scientific communication, and the limitations of the non-SI readers trapped into the International System of Impact Factors rather than guided towards implementing the International System of Units. What is the numerical value and the practical meaning of the Impact Factor of this SI publication?


Technical comments

Spelling

Since 'small spelling variations occur in the language of the English speaking countries (for instance, "metre" and "meter", "litre" and "liter")' (p. 124), a decision should be taken for consistent spelling in a document. The English text of the SI brochure follows the style "metre" and "litre". It is found that in the scientific literature the spelling style "meter" and "liter" prevails even in European journals. Below are direct quotes from the SI brochure (with reference to the page number in the 9th edition), implementing corresponding changes in spelling style.


Quantity calculus (p. 147)

Symbols for units are treated as mathematical entities. In expressing the value of a quantity as the product of a numerical value and a unit, both the numerical value and the unit may be treated by the ordinary rules of algebra. This procedure is described as the use of quantity calculus, or the algebra of quantities. For example, the equation p = 48 kPa may equally be written as p/kPa = 48. It is common practice to write the quotient of a quantity and a unit in this way for a column heading in a table, so that the entries in the table are simply numbers.
Suggestion: p/[kPa] = 48


Quantity symbols and unit symbols (p. 149)

Unit symbols must not be used to provide specific information about the quantity and should never be the sole source of information on the quantity. Units are never qualified by further information about the nature of the quantity; any extra information on the nature of the quantity should be attached to the quantity symbol and not to the unit symbol.
Comment: Quantity calculus can be extended by providing specific information about the entity (e.g. entity O2, not the quantity 'amount') together with the unit symbol, e.g., [mol O2] or [kJ·mol-1 O2], where the entity-type is not presented in the place occupied by the unit symbol for division or multiplication, respectively.


No comment

Defining the unit of a quantity (p. 127)

The value of a quantity is generally expressed as the product of a number and a unit. The unit is simply a particular example of the quantity concerned which is used as a reference, and the number is the ratio of the value of the quantity to the unit.
For example, the speed of light in vacuum is a constant of nature, denoted by c, whose value in SI units is given by the relation c = 299 792 458 m/s where the numerical value is 299 792 458 and the unit is m/s.
For a particular quantity different units may be used. For example, the value of the speed v of a particle may be expressed as v = 25 m/s or v = 90 km/h, where meter per second and kilometer per hour are alternative units for the same value of the quantity speed.
Before stating the result of a measurement, it is essential that the quantity being presented is adequately described. This may be simple, as in the case of the length of a particular steel rod, but can become more complex when higher accuracy is required and where additional parameters, such as temperature, need to be specified.
When a measurement result of a quantity is reported, the estimated value of the measurand (the quantity to be measured), and the uncertainty associated with that value, are necessary. Both are expressed in the same unit.


Canonical comments

Definition of the SI (p. 127)

As for any quantity, the value of a fundamental constant can be expressed as the product of a number and a unit.
The definitions below specify the exact numerical value of each constant when its value is expressed in the corresponding SI unit. By fixing the exact numerical value the unit becomes defined, since the product of the numerical value and the unit has to equal the value of the constant, which is postulated to be invariant.
Comment: The terms 'numerical value' and 'number' are used as being equivalent: value = "product of a number and a unit"; value = "product of the numerical value and the unit". It should be considered to define: quantity Q = product of the numerical value of a number N and a unit uQ. Symbols for specific quantities Q are, e.g., m and V for mass and volume, respectively. Do they represent merely the quantity type? Interpret a formula such as m = 60 kg: The symbol m represents the quantity 'mass', the numerical value of the number N is 60 (N = 60), the unit is um = kg, and the value of the quantity m is 60 kg. Just in case that these definitions appear to be acceptable, then it follows: quantity m = value of the quantity m.
The seven constants are chosen in such a way that any unit of the SI can be written either through a defining constant itself or through products or quotients of defining constants.
The International System of Units, the SI, is the system of units in which
  • the unperturbed ground state hyperfine transition frequency of the caesium 133 atom ∆νCs is 9 192 631 770 Hz,
  • the speed of light in vacuum c is 299 792 458 m/s,
  • the Planck constant h is 6.626 070 15 × 10−34 J s,
  • the elementary charge e is 1.602 176 634 × 10−19 C x-1,
  • the Boltzmann constant k is 1.380 649 × 10−23 J x-1 K-1,
  • the Avogadro constant NA is 6.022 140 76 × 1023 x mol−1,
  • the luminous efficacy of monochromatic radiation of frequency 540 × 1012 Hz, Kcd, is 683 lm/W,
where the hertz, joule, coulomb, lumen, and watt, with unit symbols Hz, J, C, lm, and W, respectively, are related to the units second, meter, kilogram, ampere, kelvin, mole, and candela, with unit symbols s, m, kg, A, K, mol, and cd, respectively, according to Hz = s–1, J = kg m2 s–2, C = A s, lm = cd m2 m–2 = cd sr, and W = kg m2 s–3.
The numerical values of the seven defining constants have no uncertainty.


Writing and printing of unit symbols and of numbers (p. 162)

Roman (upright) type, in general lower-case, is used for symbols of units; if, however, the symbols are derived from proper names, capital roman type is used. These symbols are not followed by a full stop.
Comment: ##
In numbers, the comma (French practice) or the dot (British practice) is used only to separate the integral part of numbers from the decimal part. Numbers may be divided in groups of three in order to facilitate reading; neither dots nor commas are ever inserted in the spaces between groups.
Comment: In the last sentence above, there is a confusion between numbers, numerals (representing numbers, such as 4, 12, 5093.78, 6, in a specific numeral system), and symbols (or characters, such as the ten characters in the decimal numeral system: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ). When a large number is expressed by a numeral as a string of several symbols, the symbols may be divided in groups of three ..  
SI-units-elementary quantities.png
Quantity Symbol for quantity Q Symbol for dimension Name of abstract unit uQ Symbol for unit uQ [*]
elementary entity *,$ UX U elementary unit x
count *,$ NX = N·UX X elementary unit x
amount of substance *,§ nX = NX·NA-1 N mole mol
charge *,€ Qel = zX·e·NX I·T coulomb C = A·s
length l L meter m
mass m M kilogram kg
time t T second s
electric current I I ampere A
thermodynamic temperature T Θ kelvin K
luminous intensity Iv J candela cd
[*] SI units, except for the canonical 'elementary unit' [x]. The following footnotes are canonical comments, related to iconic symbols.
* For the elementary quantities NX, nX, and Qel, the entity-type X of the elementary entity UX has to be specified in the text and indicated by a subscript: nO2; Nce; Qel.
$ Count NX equals the number of elementary entities UX. In the SI, the quantity 'count' is explicitly considered as an exception: "Each of the seven base quantities used in the SI is regarded as having its own dimension. .. All other quantities, with the exception of counts, are derived quantities" (Bureau International des Poids et Mesures 2019 The International System of Units (SI)). An elementary entity UX is a material unit, it is not a count (UX is not a number of UX). NX has the dimension X of a count and UX has the dimension U of an elementary entity; both quantities have the same abstract unit, the 'elementary unit' [x].
§ Amount nX is an elementary quantity, converting the elementary unit [x] into the SI base unit mole [mol] using the Avogadro constant NA.
Charge is a derived SI quantity. Charge is an elementary quantity, converting the elementary unit [x] into coulombs [C] using the elementary charge e, or converting moles [mol] into coulombs [C] using the Faraday constant F. zX is the charge number per elementary entity UX, which is a constant for any defined elementary entity UX. Qel = zX·F·nX

Keywords—MitoPedia


SI-units.png


Click to expand or collaps
Bioblast links: SI base units - >>>>>>> - Click on [Expand] or [Collapse] - >>>>>>>
Entity, count, and number, and SI base quantities / SI base units
SI-units.png
Quantity name Symbol Unit name Symbol Comment
elementary UX elementary unit [x] UX, UB; [x] not in SI
count NX elementary unit [x] NX, NB; [x] not in SI
number N - dimensionless = NX·UX-1
amount of substance nB mole [mol] nX, nB
electric current I ampere [A] A = C·s-1
time t second [s]
length l meter [m] SI: metre
mass m kilogram [kg]
thermodynamic temperature T kelvin [K]
luminous intensity IV candela [cd]
Fundamental relationships
» Avogadro constant NA
» Boltzmann constant k
» elementary charge e
» Faraday constant F
» gas constant R
» electrochemical constant f
SI and related concepts
» International System of Units
» elementary unit x
» SI prefixes
» International Union of Pure and Applied Chemistry, IUPAC
» entity
» quantity
» dimension
» format
» motive unit
» iconic symbols



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Amount of substance, Avogadro constant, Concentration, Count, Density, Dimension, International System of Units, MitoFit 2020.4, Volume, Quantity