Accreditation and Quality Assurance

, Volume 16, Issue 3, pp 121–132 | Cite as

A skeptic’s review of the New SI

  • Gary PriceEmail author


Proposals in draft form have been circulated for new Système International (SI) measurement units that are expected to be official instruments of the Treaty of the Metre by 2015. This review outlines the substance of the proposals and examines some of the consequences of the continuing evolution of the SI toward inter-dependence of base units and quantities since its introduction in 1960. The proposals in question fix at an exact value a number of inter-related fundamental natural constants such as the speed of light, the Planck constant, the elementary charge and Boltzmann’s constant. All SI units are then so defined that their magnitude is set by those fixed values. Notably, the ongoing confusions about chemical measurements and the thermodynamic ‘mole’ are exacerbated. On the big principles of the basic purpose of the SI to facilitate communication and the fixing of fundamental physical constants of nature, there are significant problems and unanswered questions. They risk: damage to the enterprise of science; wide economic loss including increased transaction costs and barriers to global trade; barriers to new technologies and to improvements in measurement accuracy; loss of measurement compatibility or consistency; and a circular global measurement system vulnerable to undetectable systematic errors with serious adverse consequences for environmental decision making among many other vital human activities. The New SI requires frank and open discussion throughout science, technology, industry, trade, and global policy well before irreversible decisions are made.


Measurement units Physical constants SI quantities Policy 



I thank the reviewers for their engagement, searching questions, and thoughtful suggestions.


  1. 1.
    Mills I, Mohr T, Taylor B, Williams E (2006) Redefinition of the kilogram, ampere, Kelvin and mole: a proposed approach to implementing CIPM recommendation 1 (CI-2005). Metrologia 43:227–246. doi: 101007/s00769-009-0529-4 CrossRefGoogle Scholar
  2. 2.
    Petley B (1985) The fundamental physical constants and the frontiers of metrology. Adam Hilger, Bristol. ISBN 0852744277Google Scholar
  3. 3.
    Pavese F (2010) Some reflections on the proposed redefinition of the unit for amount of substance and of other units. Accred Qual Assur, doi:  10.1007/s00769-010-0700-y
  4. 4.
  5. 5.
    BIPM (2006) The International System of Units (SI), 8th edn. Intergovernmental Organisation of the Treaty of the Metre, Sevres FranceGoogle Scholar
  6. 6.
    Price G (2010) Failures of the global measurement system. Part 1: the case of chemistry. Accred Qual Assur 15:421–427. doi: 10.1007/s00769-010-0655-z CrossRefGoogle Scholar
  7. 7.
    Mari L (2009) On (kinds of) quantities. Metrologia 46:L11. doi: 10.1088/0026-1394/46/3/NO1 CrossRefGoogle Scholar
  8. 8.
    De Boer J (1968–1970) Some general aspects of the International System of units Recuil de Traveaux du BIPM vol 2. BIPM, SevresGoogle Scholar
  9. 9.
    Emerson W (2004) On the algebra of quantities and their units. Metrologia 41:L33–L37. doi: 10.1088/0026-1394/41/6/L02 CrossRefGoogle Scholar
  10. 10.
    Emerson W (2008) On quantity calculus and units of measurement. Metrologia 45:134–138. doi: 10.1088/0026-1394/45/2/002 CrossRefGoogle Scholar
  11. 11.
    Leonard B (2007) The atomic scale unit, entity: key to a direct and easily understood definition of the SI base unit for amount of substance. Metrologia 44:402–406. doi: 1088/0026-1394/44/5/017 CrossRefGoogle Scholar
  12. 12.
    De Bievre P (2007) Numerosity versus mass. Accred Qual Assur 11:1–2. doi: 10.1007/s00769-007-0268-3 CrossRefGoogle Scholar
  13. 13.
    Price G, De Bievre P (2009) Simple principles for metrology in chemistry: identifying and counting. Accred Qual Assur 14:295–305. doi: 10.1007/s/00769-009-0529-4 CrossRefGoogle Scholar
  14. 14.
    McGlashan M (1995) Amount of substance and the mole. Metrologia 31:447. doi: 10.1088/0026-1394/31/6/004 CrossRefGoogle Scholar
  15. 15.
    Mills I, Milton M (2009) Amount of substance and the mole. Chemistry International 31(2)
  16. 16.
    Milton M, Mills I (2009) Amount of substance and the proposed redefinition of the mole. Metrologia 46:332–338. doi: 10.1088/0026-1394/46/3/022 CrossRefGoogle Scholar
  17. 17.
    Belanger B (1980) Traceability: an evolving concept. ASTM Stand News 8(1):22–28Google Scholar
  18. 18.
    Kula W (1986) Measures and men. Princeton University Press, Princeton, New Jersey, USA. ISBN 0-691-05446-0Google Scholar
  19. 19.
    Jammer M (1964) Concepts of mass in classical and modern physics. Harper and Rowe, New York. ISBN 0486299988Google Scholar
  20. 20.
    Foster M (2010) The next 50 years of the SI: a review of the opportunities for the e-Science age. Metrologia 47:R41–R51. doi: 10.1088/0026-1394/47/6/R01 CrossRefGoogle Scholar
  21. 21.
    White R (2010) The meaning of measurement in metrology. Accred Qual Assur doi: 10.1007/s00769-010-0698-1
  22. 22.
    Torrens A (1986) On angles and angular quantities. Metrologia 22:1–7CrossRefGoogle Scholar
  23. 23.
    Brownstein K (1997) Angles-lets treat them squarely. Am J Phys 65(7):605–613CrossRefGoogle Scholar
  24. 24.
    Yudin M (1998) The problem of the choice of the basic SI units. Measurement Techniques 41(9):873CrossRefGoogle Scholar
  25. 25.
    Emerson W (2002) A reply to “Definitions of the units radian, neper, bel and decibel” by IM Mills et al. Metrologia 39:105–109CrossRefGoogle Scholar
  26. 26.
    Emerson W (2005) Differing angles on angle. Metrologia 42:L23–L26. doi: 10.1088/0026-1394/42/4/L02 CrossRefGoogle Scholar
  27. 27.
    Galbraith J (1954) The great crash: 1929 reprint edition 2009. Mariner Books, New York. ISBN 978-0547248165Google Scholar
  28. 28.
    Emerson W (2004) One as a ‘unit’ in expressing the magnitude of quantities. Metrologia 41:L26–L28. doi: 10.1088/0026-1394/41/4/L03 CrossRefGoogle Scholar
  29. 29.
    Leonard B (2007) On the role of the Avogadro constant in redefining SI units for mass and amount of substance. Metrologia 44:82–86. doi: 10.1088/0026-1394/44/1/012 CrossRefGoogle Scholar
  30. 30.
    Leonard B (2010) Comment on recent proposals for redefining the mole and kilogram. Metrologia 47(33):L5–L8. doi: 10.1088/0026-1394/47/3/L01 CrossRefGoogle Scholar
  31. 31.
    Uzan J (2003) The fundamental constants and their variation: observational status and theoretical motivations. Rev Mod Phys 75:403–455. doi: 10.1103/RevModPhys.75.403(arXiv:hep-ph/0205340) CrossRefGoogle Scholar
  32. 32.
    Barrow J (1999) Cosmologies with varying light speed. Phys Rev D 59:043515. doi: 10.1103/PhysRevD59.043515(arXiv:astro-ph/9811022) CrossRefGoogle Scholar
  33. 33.
    Dirac P (1974) Cosmological models and the large number hypothesis. Proc R Soc A338:439–446Google Scholar
  34. 34.
    Ellis G (2007) Note on varying speed of light cosmologies. Gen relative Gravit 39:511–520. doi: 10.1007/s10714-007-0396-4 CrossRefGoogle Scholar
  35. 35.
    Troitskii V (1987) Physical constants and the evolution of the universe. Astrophys Space sci 139:389–411CrossRefGoogle Scholar
  36. 36.
    Birge R (1941) A new table of the general physical constants. Rev Mod Phys 13:233–239CrossRefGoogle Scholar
  37. 37.
    Dorsey N (1944) The velocity of light. Transactions of the American physical society, 34(1)Google Scholar
  38. 38.
    Birge R (1957) A survey of the systematic evaluation of the physical constants. Il Nuovo Cimento (1955-1965) 6 (supplement 1):36–67Google Scholar
  39. 39.
    Sheldrake R (1994) Seven experiments that could change the world: a do-it-yourself guide to revolutionary science Fourth Estate Ltd, GB ISBN: 1573225649Google Scholar
  40. 40.
    Milne E (1935) Relativity gravity and world structure. Oxford University Press, Oxford EnglandGoogle Scholar
  41. 41.
    Dirac P (1937) The cosmological constants. Nature 139:323. doi: 10.1038/139323a0 CrossRefGoogle Scholar
  42. 42.
    Gamow G (1967) Electricity, gravity and cosmology. Phys Rev Lett 19:913. doi: 10.1103PhysRevLett.19.259 CrossRefGoogle Scholar
  43. 43.
    Gamow G (1967) Variability of electric charge and quasi-stellar objects. Phys Rev Lett 19:913. doi: 10.1103PhysRevLett.19.913 CrossRefGoogle Scholar
  44. 44.
    Webb J et al (2001) Further evidence for cosmological evolution of the fine structure constant. Phys Rev Lett 87:091301CrossRefGoogle Scholar
  45. 45.
    Webb J et al. (2002) Does the fine structure constant vary? A third quasar absorption sample consistent with varying alpha. Scholar
  46. 46.
    Tranavaris P, Webb J, Murphy M, Flambaum V, Curran S (2005) Limits on variation in fundamental constants from 21-cm and ultraviolet quasar absorption lines. Phys Rev Lett 95(4):041301CrossRefGoogle Scholar
  47. 47.
    Webb J, King J, Murphy M, Flambaum V, Carswell B, Bainbridge M. (2010) Evidence for spatial variation of the fine structure constant. Phys Rev Lett
  48. 48.
    Berengut J, Flambaum V, King J, Curran S, Webb J (2010) Is there further evidence for spatial variation of fundamental constants?
  49. 49.
    Berengut J, Flambaum V (2010) Manifestations of a spatial variation of fundamental constants on atomic clocks, Oklo, meteorites and cosmological phenomena.
  50. 50.
    BIPM, IEC, IFCC, ILAC, ISO, IUPAC, IUPAP, OIML (2008) International vocabulary of metrology—basic and general concepts and associated terms (VIM) 3rd edn. BIPM Sevres France.
  51. 51.
    Kind D, Quinn T (1995) Metrology: Quo Vadis? IEEE Instrumentation and Measurement 44(2). doi:  10.1109/19.377779
  52. 52.
    Price G (2010) Failures of the global measurement system. Part 2: Institutions, instruments and strategy. Accred Qual Assur 15:477–484. doi: 10.1007/s00769-010-0662-0 CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.MenaiAustralia

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