A further layman explanation by a researcher in this field: http://astronomy.swin.edu.au/~mmurphy/research/are-natures-laws-really-universal/ http://astronomy.s

A further layman explanation by a researcher in this field: http://astronomy.swin.edu.au/~mmurphy/research/are-natures-laws-really-universal/ http://astronomy.swin.edu.au/~mmurphy/research/are-natures-l... specifically the section titled "Aside: Is it e or c varying?"