[LINK] Forty Years of String Theory: Reflecting on the Foundations

Those of us in­ter­ested in “fun­da­men­tal physics” may find a few in­ter­est­ing tid­bits in the lat­est is­sue of Springer’s Foun­da­tions of Physics. It has con­tri­bu­tions from the promi­nent figures in String The­ory and re­lated fields, such as the No­bel lau­re­ate Ger­ard ’t Hooft, father of the an­thropic land­scape Leonard Susskind and one of the founders of the lead­ing al­ter­na­tive to the String The­ory, Loop Quan­tum Grav­ity, as well as the au­thor of sev­eral pop­u­lar books about fun­da­men­tal physics Lee Smolin. Eric Ver­linde, the au­thor of the con­tro­ver­sial En­tropic grav­ity model, also con­tributed. A cou­ple of philoso­phers of sci­ence added their two cents.

While Springer is not an open-ac­cess pub­lisher, this vol­ume is free, as are many oth­ers dur­ing De­cem­ber 2012.

A few quotes from the in­tro­duc­tion, which seem rele­vant to the is­sues of truth, re­al­ism and ra­tio­nal­ity:

“He [’t Hooft] com­pares string the­ory to other the­o­ries and mod­els which are not free of prob­lems but we gen­er­ally con­sider to be well-defined: ce­les­tial clas­si­cal me­chan­ics, quan­tum me­chan­ics, and QCD, and con­cludes that string the­ory is not in as good shape as any of these the­o­ries.”

“Rick­les de­vel­ops a ver­sion of the “no-mir­a­cles ar­gu­ment” for sci­en­tific re­al­ism to the case of math­e­mat­i­cally fruit­ful the­o­ries, thereby defend­ing the ra­tio­nal­ity of those who pur­sue string the­ory in the ab­sence of bet­ter al­ter­na­tives, rather than mak­ing a state­ment about the truth of the the­ory.”

“Susskind ar­gues that de­vel­op­ments in string the­ory are tel­ling us that a nar­row form of re­duc­tion­ism is wrong: “[I]f one listens care­fully, string the­ory is tel­ling us that in a deep way re­duc­tion­ism is wrong, at least be­yond some point.” The rea­son is that var­i­ous string du­al­ities in­ter­change what is fun­da­men­tal and what is com­pos­ite, large and small lengths scales, high-di­men­sional ob­jects with lower-di­men­sional ob­jects, and so on. Ac­cord­ing to Susskind, “In string the­ory this kind of am­bi­guity is the rule.” “Per­son­ally, I would bet that this kind of anti-re­duc­tion­ist be­hav­ior is true in any con­sis­tent syn­the­sis of quan­tum me­chan­ics and grav­ity.””

If you were to read only one pa­per, make it the one by Michael Duff. Here is the ab­stract:

Us­ing as a spring­board a three-way de­bate be­tween the­o­ret­i­cal physi­cist Lee Smolin, philoso­pher of sci­ence Nancy Cartwright and my­self, I ad­dress in lay­man’s terms the is­sues of why we need a unified the­ory of the fun­da­men­tal in­ter­ac­tions and why, in my opinion, string and M-the­ory cur­rently offer the best hope. The fo­cus will be on re­spond­ing more gen­er­ally to the var­i­ous crit­i­cisms. I also de­scribe the di­verse ap­pli­ca­tion of string/​M-the­ory tech­niques to other branches of physics and math­e­mat­ics which ren­der the whole en­ter­prise worth­while whether or not “a the­ory of ev­ery­thing” is forth­com­ing.”