A further layman explanation by a researcher in this field: <a href="http:&#x2F;&#x2F;astronomy.swin.edu.au&#x2F;~mmurphy&#x2F;research&#x2F;are-natures-laws-really-universal&#x2F;" rel="nofollow">http:&#x2F;&#x2F;astronomy.swin.edu.au&#x2F;~mmurphy&#x2F;research&#x2F;are-natures-l...</a> specifically the section titled &quot;Aside: Is it e or c varying?&quot;