{"id":312,"date":"2011-01-15T17:57:08","date_gmt":"2011-01-15T22:57:08","guid":{"rendered":"http:\/\/www.fruechtetheory.com\/blog\/?p=312"},"modified":"2011-01-15T17:57:08","modified_gmt":"2011-01-15T22:57:08","slug":"permittivity-of-free-space","status":"publish","type":"post","link":"https:\/\/www.fruechtetheory.com\/blog\/2011\/01\/15\/permittivity-of-free-space\/","title":{"rendered":"Permittivity of Free Space"},"content":{"rendered":"<p>It is interesting, to say the least, the way some of the constants of physics mix and match.\u00a0 There are lots of examples of this in text books and on web sites, including this one, so there is no point in reiterating any now which do not relate specifically to this entry.<\/p>\n<p>Some constants, nevertheless, turn out not to be constants, including the permittivity of free space, termed \u03b5<sub>0<\/sub>.\u00a0 At the surface of the earth, and at any point not far enough away to discern a difference, we have \u03b5<sub>0<\/sub> = 8.85 x 10<sup>-12<\/sup> C<sup>2<\/sup>\/(N-m<sup>2<\/sup>) when measured in a vacuum.\u00a0 One of the ways in which the permittivity of free space relates to other physical entities is in the makeup of the Coulomb constant, k = 1\/(4\u03c0\u03b5<sub>0<\/sub>), which is then also not really a constant in all locations, the difference relating to the local density of gravitons.<\/p>\n<p>The speed of light in a vacuum can be written as: c = sqrt(k\/k<sub>m<\/sub>) = 1\/sqrt(\u03b5<sub>0<\/sub> \u00b5<sub>0<\/sub>) = 2.998 x 10<sup>8<\/sup> m\/s, which is a constant throughout the universe.\u00a0 One may be tempted to say then that \u00b5<sub>0<\/sub> is an inverse function to \u03b5<sub>0<\/sub> when evaluated at a given point, except that this is so unlikely with present understanding so as to be unimaginable.\u00a0 Along with the constancy of the speed of light in a vacuum in any reference frame, the fact that it equals 1\/sqrt(\u03b5<sub>0<\/sub> \u00b5<sub>0<\/sub>) in our locale can remain somewhat of a mystery.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>It is interesting, to say the least, the way some of the constants of physics mix and match.\u00a0 There are lots of examples of this in text books and on web sites, including this one, so there is no point in reiterating any now which do not relate specifically to this entry. Some constants, nevertheless, [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,7,13],"tags":[],"class_list":["post-312","post","type-post","status-publish","format-standard","hentry","category-astrophysics","category-classical-electrodynamics","category-general-relativity"],"_links":{"self":[{"href":"https:\/\/www.fruechtetheory.com\/blog\/wp-json\/wp\/v2\/posts\/312","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.fruechtetheory.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fruechtetheory.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fruechtetheory.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fruechtetheory.com\/blog\/wp-json\/wp\/v2\/comments?post=312"}],"version-history":[{"count":1,"href":"https:\/\/www.fruechtetheory.com\/blog\/wp-json\/wp\/v2\/posts\/312\/revisions"}],"predecessor-version":[{"id":313,"href":"https:\/\/www.fruechtetheory.com\/blog\/wp-json\/wp\/v2\/posts\/312\/revisions\/313"}],"wp:attachment":[{"href":"https:\/\/www.fruechtetheory.com\/blog\/wp-json\/wp\/v2\/media?parent=312"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fruechtetheory.com\/blog\/wp-json\/wp\/v2\/categories?post=312"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fruechtetheory.com\/blog\/wp-json\/wp\/v2\/tags?post=312"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}