{"id":80,"date":"2004-09-17T18:24:09","date_gmt":"2004-09-17T22:24:09","guid":{"rendered":"http:\/\/www.math.columbia.edu\/~woit\/wordpress\/?p=80"},"modified":"2004-09-17T18:24:09","modified_gmt":"2004-09-17T22:24:09","slug":"motl-on-string-field-theory","status":"publish","type":"post","link":"https:\/\/www.math.columbia.edu\/~woit\/wordpress\/?p=80","title":{"rendered":"Motl on String Field Theory"},"content":{"rendered":"<p>Lubos Motl has an interesting post on sci.physics.stringsthat gives a detailed <A href=\"http:\/\/groups.google.com\/groups?dq=&#038;hl=en&#038;lr=&#038;ie=UTF-8&#038;group=sci.physics.strings&#038;selm=Pine.LNX.4.31.0409151145350.2121-100000%40feynman.harvard.edu\"> explanation<\/A> of the current state of string field theory.  <\/p>\n<p>One way of motivating quantum field theory is to start with a &#8220;first-quantized&#8221;  quantum theory of particles (perhaps defined by integrating over paths), then &#8220;second-quantize&#8221; by considering a quantum theory of fields, where the fields are defined on the space the points in the path move in.  The natural generalization to string theory would be to start with the &#8220;first-quantized&#8221; theory of strings given by doing path integrals over the possible worldsheets traced out by the moving strings (these are conformal field theories), then &#8220;second quantize&#8221; by quantizing fields defined on the infinite dimensional space of loops.  It has always been a hope of string theorists that this would somehow give a true non-perturbative definition of string theory.<\/p>\n<p>Lubos explains what some of the problems with this idea are.  For one thing it is in conflict with the M-theory philosophy that a non-perturbative theory should involve on the same footing not just strings, but also higher dimensional &#8220;branes&#8221;.  He goes on to speculate about what can be done about this problem, saying that perhaps one shouldn&#8217;t be trying to find a fundamental set of degrees of freedom and an action functional of them.  Instead maybe one just needs to find a set of self-consistent rules, which will be obeyed by all sorts of different degrees of freedom. As he notes at   the end, this is similar to the old &#8220;Bootstrap Philosophy&#8221; of Chew and others that dominated thinking about the strong interactions during the 1960&#8217;s.  It didn&#8217;t work then, and I&#8217;ll bet it won&#8217;t work now.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Lubos Motl has an interesting post on sci.physics.stringsthat gives a detailed explanation of the current state of string field theory. One way of motivating quantum field theory is to start with a &#8220;first-quantized&#8221; quantum theory of particles (perhaps defined by &hellip; <a href=\"https:\/\/www.math.columbia.edu\/~woit\/wordpress\/?p=80\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-80","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.math.columbia.edu\/~woit\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/80","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.math.columbia.edu\/~woit\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.math.columbia.edu\/~woit\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.math.columbia.edu\/~woit\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.math.columbia.edu\/~woit\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=80"}],"version-history":[{"count":0,"href":"https:\/\/www.math.columbia.edu\/~woit\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/80\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.math.columbia.edu\/~woit\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=80"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.math.columbia.edu\/~woit\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=80"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.math.columbia.edu\/~woit\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=80"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}