History of Proton-to-electron mass ratio

+Title: Proton-to-electron mass ratio+Definition: The proton-to-electron mass ratio $\mu$ is the quotient of  the rest mass+  of a proton by the rest mass of an electron.+Parameters:+  expression:+    title: Transformation of constant+    type: Symbolic+    show-in-parameter-list: 'no'+Comments:+  comment-non-constant: $\mu$ may not be constant CITE{WikiNC}.+Formulas: {}+Programs: {}+References:+  Bar03:+    bib: 'John D. Barrow, "The Constants of Nature: From Alpha to Omega -- the Numbers+      That Encode the Deepest Secrets of the Universe", 2003.'+Links:+  Wiki:+    title: 'Wikipedia: Proton-to-electron mass ratio'+    url: https://en.wikipedia.org/wiki/Proton-to-electron_mass_ratio+  WikiNC:+    title: 'Wikipedia: Proton-to-electron mass ratio: Variation over time'+    url: https://en.wikipedia.org/wiki/Proton-to-electron_mass_ratio#Variation_of_%CE%BC_over_time+Similar tables: ''+Keywords: ''+Tags:+- physics+- dimensionless+Data properties:+  type: RB+  sources:+  - CITE{Bar03}+  reliability: The given real interval is chosen to contain  the measurement up to+    five measurement uncertainties that are displayed in CITE{Bar03}.+Numbers:+  mu:+    param-latex: $\mu$+    number: 1836.152673430 +/- 5.51e-7+  mu_inv:+    param-latex: $\mu^{-1}$+    number: 0.000544617021488 +/- 1.64e-13