{"id":317,"date":"2010-07-27T22:27:19","date_gmt":"2010-07-27T22:27:19","guid":{"rendered":"http:\/\/labrigger.com\/blog\/?p=317"},"modified":"2010-07-27T22:27:19","modified_gmt":"2010-07-27T22:27:19","slug":"street-fighting-mathematics","status":"publish","type":"post","link":"http:\/\/labrigger.com\/blog\/2010\/07\/27\/street-fighting-mathematics\/","title":{"rendered":"Street fighting mathematics"},"content":{"rendered":"<p align=\"center\"><a href=\"http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2010\/07\/streetfightingmath.jpg\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2010\/07\/streetfightingmath.jpg\" alt=\"\" title=\"streetfightingmath\" width=\"369\" height=\"475\" class=\"aligncenter size-full wp-image-321\" srcset=\"http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2010\/07\/streetfightingmath.jpg 369w, http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2010\/07\/streetfightingmath-233x300.jpg 233w\" sizes=\"auto, (max-width: 369px) 100vw, 369px\" \/><\/a><\/p>\n<p>Physicists have a very unsentimental way of manhandling mathematics. In addition to setting up dimensionally inconsistent equations for order-of-magnitude estimations, they like to take lots of short cuts that make computations fast and easy. For example, in the <a href=\"http:\/\/en.wikipedia.org\/wiki\/Atomic_units\">Hartree atomic unit system<\/a>, several fundamental quantities are all set equal to 1. Electron mass, electron charge, Planck&#8217;s constant, and Coulomb&#8217;s constant&#8211; all are set to 1. One time, in the middle of a derivation, my plasma physics professor crossed out a 2 and wrote 1, saying, &#8220;in plasma physics, 2 is 1; sometimes 10 is 1; 5 is always 1.&#8221; Another trick was expressing the number of seconds in a year as pi * 10<sup>7<\/sup>; this is accurate to better than 0.5%!<\/p>\n<p>The book &#8220;Street-fighting Mathematics&#8221; by Sanjoy Mahajan (MIT Press) teaches a lot of tricks like these. Plus, Mahajan does an excellent job of training the reader in how to approach physics problems and apply logical shortcuts. Check out <a href=\"http:\/\/ocw.mit.edu\/courses\/mathematics\/18-098-street-fighting-mathematics-january-iap-2008\/readings\/\">some of the material<\/a> using MIT&#8217;s Open Courseware site.<\/p>\n","protected":false},"excerpt":{"rendered":"<p align=\"center\"><a href=\"http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2010\/07\/streetfightingmath.jpg\"><\/a><\/p>\n<p>Physicists have a very unsentimental way of manhandling mathematics. In addition to setting up dimensionally inconsistent equations for order-of-magnitude estimations, they like to take lots of short cuts that make computations fast and&#8230;<\/p>\n<div class=\"read-more\"><a href=\"http:\/\/labrigger.com\/blog\/2010\/07\/27\/street-fighting-mathematics\/\">Read More<\/a><\/div><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[20],"class_list":["post-317","post","type-post","status-publish","format-standard","hentry","category-tips","tag-references"],"_links":{"self":[{"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/posts\/317","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/comments?post=317"}],"version-history":[{"count":6,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/posts\/317\/revisions"}],"predecessor-version":[{"id":324,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/posts\/317\/revisions\/324"}],"wp:attachment":[{"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/media?parent=317"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/categories?post=317"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/tags?post=317"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}