2014/12/02 by M. J. Duff · 2 citations
Physics and Astronomy · #Quantum Mechanics and Applications #Radioactive Decay and Measurement Techniques #Relativity and Gravitational Theory #gr-qc #hep-ph #hep-th #physics.hist-ph
paper · pdf · doi:10.1080/00107514.2014.980093
Note added. 30 pages latex. 7 figures. arXiv admin note: text overlap with arXiv:hep-th/0208093 (unpublished)
openalex publication_date 2014/12/02 · arxiv created 2014/12/17 · arxiv updated 2014/12/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
I argue that the laws of physics should be independent of one’s choice of units or measuring apparatus. This is the case if they are framed in terms of dimensionless numbers such as the fine structure constant, α. For example, the standard model of particle physics has 19 such dimensionless parameters whose values all observers can agree on, irrespective of what clock, rulers or scales… they use to measure them. Dimensional constants, on the other hand, such as ħ, c, G, e and k …, are merely human constructs whose number and values differ from one choice of units to the next. In this sense, only dimensionless constants are ‘fundamental’. Similarly, the possible time variation of dimensionless fundamental ‘constants’ of nature is operationally well defined and a legitimate subject of physical enquiry. By contrast, the time variation of dimensional constants such as c or G on which a good many (in my opinion, confusing) papers have been written, is a unit-dependent phenomenon on which different observers might disagree depending on their apparatus. All these confusions disappear if one asks only unit-independent questions. We provide a selection of opposing opinions in the literature and respond accordingly.