{"id":649,"date":"2008-10-14T16:00:56","date_gmt":"2008-10-14T23:00:56","guid":{"rendered":"https:\/\/www.reenigne.org\/blog\/?p=649"},"modified":"2008-09-14T18:35:29","modified_gmt":"2008-09-15T01:35:29","slug":"godels-incompleteness-theorem","status":"publish","type":"post","link":"https:\/\/www.reenigne.org\/blog\/godels-incompleteness-theorem\/","title":{"rendered":"G\u00f6del&#8217;s incompleteness theorem"},"content":{"rendered":"<p>G\u00f6del&#8217;s incompleteness theorem is an interesting little piece of mathematics but probably gets talked about more than it really deserves to be. I&#8217;m going to add to the problem here by talking about it.<\/p>\n<p>It&#8217;s a pretty simple idea really &#8211; if you have a formal system of mathematics F sufficiently rich to do anything interesting, you can write down a statement G that says, essentially, &#8220;statement G cannot be proved in formal system F&#8221;. G must be true since if it was false it would be provable and therefore true, which is a contradiction. So given any formal system you can either use it to prove a contradiction (in which case it can be used to be prove anything, and is therefore useless) or you can find a true statement that cannot be proved within the formal system. Mathematics (being a non-contradictory formal system) can therefore never be used to prove all the statements that are true. &#8220;But hang on a minute,&#8221; I hear you say, &#8220;that proof that G is true looked an awful lot like mathematics to me.&#8221; Really all this means is that the kind of things we think about as being mathematical proofs can&#8217;t be enumerated into some nice tidy finite set, since whatever you put in that set you can use to find another element that needs to be added.<\/p>\n<p>There is an analogy here with Cantor&#8217;s diagonal proof that the real numbers form a greater class of infinity than the integers. While they&#8217;re both interesting proofs there is a fundamental &#8220;infinite-ness&#8221; and &#8220;strange loop-iness&#8221; about both of them. Infinite things are strange and non-intuitive, and also useless for describing the real universe (since we can never measure anything with infinite precision).<\/p>\n","protected":false},"excerpt":{"rendered":"<p>G\u00f6del&#8217;s incompleteness theorem is an interesting little piece of mathematics but probably gets talked about more than it really deserves to be. I&#8217;m going to add to the problem here by talking about it. It&#8217;s a pretty simple idea really &#8211; if you have a formal system of mathematics F sufficiently rich to do anything [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-649","post","type-post","status-publish","format-standard","hentry","category-maths"],"_links":{"self":[{"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/posts\/649","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/comments?post=649"}],"version-history":[{"count":3,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/posts\/649\/revisions"}],"predecessor-version":[{"id":801,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/posts\/649\/revisions\/801"}],"wp:attachment":[{"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/media?parent=649"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/categories?post=649"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/tags?post=649"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}