A Stringent Limit on a Drifting Proton-to-Electron Mass Ratio from Alcohol in the Early Universe

Abstract

Varying Constant? Searches for time-varying fundamental constants provide a means to look beyond the standard model of particle physics. Bagdonaite et al. (p. 46 , published online 13 December) set an improved limit on the possible timevariation of the proton-to-electron mass ratio by comparing the frequencies of methanol transitions observed in a galaxy at a look-back time of 7 billion years with those measured in the laboratory. The values agree within 10 −7 , consistent with no variation over cosmic time.