Constants, Units and Standards

  • Jeff Flowers
  • Brian Petley
Part II Fundamental Constants
Part of the Lecture Notes in Physics book series (LNP, volume 648)


Our knowledge of the Universe depends on our ability to make measurements. Measurement is essentially a comparison process. In order to make comparisons valid for different positions in space and time a system of invariant units is required. The fundamental constants are a natural system of units in physics and have increasingly been used in practice to provide what is assumed to be an invariant, practical system of standards and units that is sufficiently constant for present-day technology. Measurement of a fundamental constant has often been limited by our ability to realise the appropriate unit. The situation then has been inverted and the relevant fundamental constant has been used in practice to define or maintain the unit.

We consider measurement as a comparison, the fundamental constants as units, whether the constants are constant, the practical realizations of the SI units, their interaction with the fundamental constants and present accuracy.1

  1. 1.

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Physical Review Letter Fundamental Constant Fundamental Physical Constant Rydberg Constant MOSFET Device 
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Authors and Affiliations

  • Jeff Flowers
    • 1
  • Brian Petley
    • 1
  1. 1.National Physical Laboratory, TeddingtonUK

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