I am almost finished watching Leonard Susskind's String Theory lecture series on Youtube, and, while I find it very accessible, there's something seriously self-contradictory about the historical model he's unraveling.

Early string theory before it was even string theory was an attempt to understand the properties of hadrons, which are fermions. Fine. Conceptualizing them as vibrating strings and then realizing that the resultant math matched the Veneziano Amplitude for mesons really clued people like Lenny in that they were onto something big, especially when it turned out that bosons like photons and gravitons naturally arose out of the equations. Fine again. Light cone frames, harmonic oscillators, conformal mapping, integrating over the Polyakov action, 26 dimensions, etc, etc.I get it.

What I don't get is Prof. Susskind makes it sound like they did succeed in getting correct data about hadrons by applying all the above tools, even if in a few years QCD and The Standard Model came along to do it better. How was this success possible for a fermion when the methods and theoretical models they were using were by the early 70's recognized even by him and his peers to be only applicable to bosons? This was a good number of years before supersymmetry and superstring theory, keep in mind.

I know my confusion is just me being ignorant, but the chronological logic seems awfully screwed up here. What am I getting wrong?

  • 2
    $\begingroup$ The pion is a hadron. It is a boson. Same for many other hadronic objects. $\endgroup$ – Mitchell Porter Nov 8 '17 at 5:19
  • $\begingroup$ Maybe that clears it up, though he did mention baryons from time to time. $\endgroup$ – ChrisW Nov 8 '17 at 5:39
  • $\begingroup$ Link to video ? $\endgroup$ – Qmechanic Nov 8 '17 at 6:21
  • $\begingroup$ the history of discovering quarks in hadrons en.wikipedia.org/wiki/Eightfold_Way_(physics) $\endgroup$ – anna v Nov 8 '17 at 7:10
  • $\begingroup$ I do feel pretty lame at this point. Whenever I hear hadrons what always comes to mind first for me is baryons, like neutrons and protons -- which are most definitely fermions. Lenny could have been discriminating in his use of the term is all I wish in hindsight. $\endgroup$ – ChrisW Nov 8 '17 at 9:37

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