Difference between revisions of "New SI"

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"'''New SI'''" or "'''quantum SI'''" are terms used to refer to a series of proposed changes in the [[International System of Units]] (SI), which will lead to the redefinition of the [[kilogram]] and up to three other [[base unit]]s in terms of fundamental [[physical constant]]s. The changes will not take effect until the 24th&nbsp;meeting of the [[General Conference on Weights and Measures]] (CGPM) in autumn 2011 at the earliest.<ref name="CGPM23">[http://www.bipm.org/en/CGPM/db/23/12/ Resolution 12], 23rd&nbsp;meeting of the [[General Conference on Weights and Measures]], 2007.</ref>
 
"'''New SI'''" or "'''quantum SI'''" are terms used to refer to a series of proposed changes in the [[International System of Units]] (SI), which will lead to the redefinition of the [[kilogram]] and up to three other [[base unit]]s in terms of fundamental [[physical constant]]s. The changes will not take effect until the 24th&nbsp;meeting of the [[General Conference on Weights and Measures]] (CGPM) in autumn 2011 at the earliest.<ref name="CGPM23">[http://www.bipm.org/en/CGPM/db/23/12/ Resolution 12], 23rd&nbsp;meeting of the [[General Conference on Weights and Measures]], 2007.</ref>
  
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The main object of "new SI" is to find an alternative for the [[International Prototype Kilogram]] as a [[mass]] standard. The kilogram is the only one of the SI base units still to be defined in terms of a [[prototype standard]], and intercomparison of national prototypes suggests that the stability of these standards is not as great as had previously been assumed.<ref>{{citation | last = Girard | first = G. | year = 1994 | title = The Third Periodic Verification of National Prototypes of the Kilogram (1988–1992) | journal = Metrologia | volume = 31 | pages = 317–336}}.</ref><ref name="CGPM20">[http://www.bipm.org/en/CGPM/db/20/5/ Resolution 5], 20th&nbsp;meeting of the [[General Conference on Weights and Measures]] (CGPM), 1995.</ref> The favoured option is to redefine the kilogram in terms of a defined value of the [[Planck constant]], although other proposals have also been made. At the same time, the redefinition of the [[mole (unit)|mole]], the [[ampere]] and the [[kelvin]] (in terms of the [[Avogadro constant]], the [[elementary charge]] and the [[Bolzmann constant]] respectively) is also under consideration.<ref name="U1-2005">Recommendation U1, [http://www.bipm.org/utils/common/pdf/CCU17.pdf 17th&nbsp;meeting of the Consultative Committee for Units (CCU)], 2005.</ref><ref name="1-CI-2005">[http://www.bipm.org/cc/CIPM/Allowed/94/CIPM-Recom1CI-2005-EN.pdf Recommendation 1 (CI-2005)], 94th&nbsp;meeting of the [[International Committee for Weights and Measures]] (CIPM), 2005.</ref>
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The main object of "new SI" is to find an alternative for the [[International Prototype Kilogram]] as a [[mass]] standard. The kilogram is the only one of the SI base units still to be defined in terms of a [[prototype standard]], and intercomparison of national prototypes suggests that the stability of these standards is not as great as had previously been assumed.<ref>{{citation | last = Girard | first = G. | year = 1994 | title = The Third Periodic Verification of National Prototypes of the Kilogram (1988–1992) | journal = Metrologia | volume = 31 | pages = 317–336}}.</ref><ref name="CGPM20">[http://www.bipm.org/en/CGPM/db/20/5/ Resolution 5], 20th&nbsp;meeting of the [[General Conference on Weights and Measures]] (CGPM), 1995.</ref> The favoured option is to redefine the kilogram in terms of a defined value of the [[Planck constant]],<ref>[Report of the 18th&nbsp;meeting of the Consultative Committee for Units (CCU)], 2007.</ref> although other proposals have also been made.<ref>{{citation | first1 = P. | last1 = Becker | first2 = P. | last2 = De Bièvre | first3 = K. | last3 = Fujii | first4 = M. | last4 = Glaeser | first5 = B. | last5 = Inglis | first6 = H. | last6 = Luebbig | first7 = G. | last7 = Mana | title = Considerations on future redefinitions of the kilogram, the mole and of other units  | journal =  Metrologia | year = 2007 | volume = 44 | issue = 1 | pages = 1–14 | doi = 10.1088/0026-1394/44/1/001}}.</ref> At the same time, the redefinition of the [[mole (unit)|mole]], the [[ampere]] and the [[kelvin]] (in terms of the [[Avogadro constant]], the [[elementary charge]] and the [[Bolzmann constant]] respectively) is also under consideration.<ref name="U1-2005">Recommendation U1, [http://www.bipm.org/utils/common/pdf/CCU17.pdf 17th&nbsp;meeting of the Consultative Committee for Units (CCU)], 2005.</ref><ref name="1-CI-2005">[http://www.bipm.org/cc/CIPM/Allowed/94/CIPM-Recom1CI-2005-EN.pdf Recommendation 1 (CI-2005)], 94th&nbsp;meeting of the [[International Committee for Weights and Measures]] (CIPM), 2005.</ref>
  
 
==Kilogram==
 
==Kilogram==
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<ref>{{citation | first1 = I. M. | last1 = Mills | first2 = P. J. | last2 = Mohr | first3 = T. J. | last3 = Quinn | first4 = B. N. | last4 = Taylor | first5 = E. R. | last5 = Williams | title = Redefinition of the kilogram, ampere, kelvin and mole: a proposed approach to implementing CIPM recommendation&nbsp;1 (CI-2005) | journal = Metrologia | volume = 43 | issue = 3 | pages = 227–46 | year = 2006 | doi = 10.1088/0026-1394/43/3/006}}.</ref>
 
<ref>{{citation | first1 = I. M. | last1 = Mills | first2 = P. J. | last2 = Mohr | first3 = T. J. | last3 = Quinn | first4 = B. N. | last4 = Taylor | first5 = E. R. | last5 = Williams | title = Redefinition of the kilogram, ampere, kelvin and mole: a proposed approach to implementing CIPM recommendation&nbsp;1 (CI-2005) | journal = Metrologia | volume = 43 | issue = 3 | pages = 227–46 | year = 2006 | doi = 10.1088/0026-1394/43/3/006}}.</ref>
 
<ref>{{citation | title = Note on invariant redefinitions of SI base units for both mass and amount of substance | first = B. P. | last = Leonard | journal = Metrologia | volume = 43 | issue = 1 | pages = L3–L5 | year = 2006 | doi = 10.1088/0026-1394/43/1/L01}}.</ref>
 
<ref>{{citation | title = Note on invariant redefinitions of SI base units for both mass and amount of substance | first = B. P. | last = Leonard | journal = Metrologia | volume = 43 | issue = 1 | pages = L3–L5 | year = 2006 | doi = 10.1088/0026-1394/43/1/L01}}.</ref>
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<ref>{{citation | first1 = P. | last1 = Becker | first2 = P. | last2 = De Bièvre | first3 = K. | last3 = Fujii | first4 = M. | last4 = Glaeser | first5 = B. | last5 = Inglis | first6 = H. | last6 = Luebbig | first7 = G. | last7 = Mana | title = Considerations on future redefinitions of the kilogram, the mole and of other units  | journal =  Metrologia | year = 2007 | volume = 44 | issue = 1 | pages = 1–14 | doi = 10.1088/0026-1394/44/1/001}}.</ref>
 
 
<ref>{{citation | title = The atomic units, the kilogram and the other proposed changes to the SI | first =  B. W. | last = Petley | year = 2007 | journal = Metrologia | volume = 44 | issue = 1 | pages = 69–72 | doi = 10.1088/0026-1394/44/1/010}}.</ref>
 
<ref>{{citation | title = The atomic units, the kilogram and the other proposed changes to the SI | first =  B. W. | last = Petley | year = 2007 | journal = Metrologia | volume = 44 | issue = 1 | pages = 69–72 | doi = 10.1088/0026-1394/44/1/010}}.</ref>
  

Revision as of 09:00, 27 August 2010

"New SI" or "quantum SI" are terms used to refer to a series of proposed changes in the International System of Units (SI), which will lead to the redefinition of the kilogram and up to three other base units in terms of fundamental physical constants. The changes will not take effect until the 24th meeting of the General Conference on Weights and Measures (CGPM) in autumn 2011 at the earliest.[1]

The main object of "new SI" is to find an alternative for the International Prototype Kilogram as a mass standard. The kilogram is the only one of the SI base units still to be defined in terms of a prototype standard, and intercomparison of national prototypes suggests that the stability of these standards is not as great as had previously been assumed.[2][3] The favoured option is to redefine the kilogram in terms of a defined value of the Planck constant,[4] although other proposals have also been made.[5] At the same time, the redefinition of the mole, the ampere and the kelvin (in terms of the Avogadro constant, the elementary charge and the Bolzmann constant respectively) is also under consideration.[6][7]

Kilogram

[3][8][9][6][7][10][1]

[11] [12] [13] [14] [15]

Mole

[16] [17] [18] [19]

Ampere

[20]

Kelvin

[21]

Notes and references

Notes

References

  1. ↑ 1.0 1.1 Resolution 12, 23rd meeting of the General Conference on Weights and Measures, 2007.
  2. ↑ Girard, G. The Third Periodic Verification of National Prototypes of the Kilogram (1988–1992). Metrologia 1994, 31, 317–336.
  3. ↑ 3.0 3.1 Resolution 5, 20th meeting of the General Conference on Weights and Measures (CGPM), 1995.
  4. ↑ [Report of the 18th meeting of the Consultative Committee for Units (CCU)], 2007.
  5. ↑ Becker, P.; De Bièvre, P.; Fujii, K.; Glaeser, M.; Inglis, B.; Luebbig, H.; Mana, G. Considerations on future redefinitions of the kilogram, the mole and of other units. Metrologia 2007, 44 (1), 1–14. DOI: 10.1088/0026-1394/44/1/001.
  6. ↑ 6.0 6.1 Recommendation U1, 17th meeting of the Consultative Committee for Units (CCU), 2005.
  7. ↑ 7.0 7.1 Recommendation 1 (CI-2005), 94th meeting of the International Committee for Weights and Measures (CIPM), 2005.
  8. ↑ Resolution 7, 21st meeting of the General Conference on Weights and Measures (CGPM), 1999.
  9. ↑ Recommendation G1, 9th meeting of the Consultative Committee for Mass and Related Quantities (CCM), 2005.
  10. ↑ Report of the CCM to the CIPM, May 2007.
  11. ↑ Schwitz, W.; Jeckelmann, B.; Richard, P. Towards a new kilogram definition based on a fundamental constant. C. R. Phys. 2004, 5 (8), 881–92.
  12. ↑ Robinson, I. Redefining the kilogram. Phys. World 2004, 17 (5), 31–35.
  13. ↑ Mills, I. M.; Mohr, P. J.; Quinn, T. J.; Taylor, B. N.; Williams, E. R. Redefinition of the kilogram, ampere, kelvin and mole: a proposed approach to implementing CIPM recommendation 1 (CI-2005). Metrologia 2006, 43 (3), 227–46. DOI: 10.1088/0026-1394/43/3/006.
  14. ↑ Leonard, B. P. Note on invariant redefinitions of SI base units for both mass and amount of substance. Metrologia 2006, 43 (1), L3–L5. DOI: 10.1088/0026-1394/43/1/L01.
  15. ↑ Petley, B. W. The atomic units, the kilogram and the other proposed changes to the SI. Metrologia 2007, 44 (1), 69–72. DOI: 10.1088/0026-1394/44/1/010.
  16. ↑ Recommendation Q1, 15th meeting of the Consultative Committee for Amount of Substance: metrology in chemistry (CCQM), 2009.
  17. ↑ Mills, Ian; Milton, Martin Amount of Substance and the Mole. Chem. Int. 2009, 31 (2), 3–7, <http://www.iupac.org/publications/ci/2009/3102/1_mills.html>.
  18. ↑ Andres, Hanspeter; Haerri, Hans-Peter; Niederhauser, Bernhard; Wunderli, Samuel; Feller, Ulrich No Rationale for a Redefinition of the Mole. Chimia Int. J. Chem. 2009, 63 (10), 616–18. DOI: 10.2533/chimia.2009.616.
  19. ↑ Leonard, B. P. Comments on recent proposals for redefining the mole and kilogram. Metrologia 2010, 47 (3), L5–L8. DOI: 10.1088/0026-1394/47/3/L01.
  20. ↑ Recommendation E1, 25th meeting of the Consultative Committee on Electricity and Magnetism, 2007.
  21. ↑ Recommendation T2, 23rd meeting of the Consultative Committee on Thermometry, 2005.
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