November 13, 2006
This essay presents a critical evaluation of the concepts of string theory and its impact on particle physics. The point of departure is a historical review of four decades of ST within the broader context of six decades of failed attempts at an autonomous S-matrix approach to particle theory. The central message, contained in sections 5 and 6, is that string theory is not what its name suggests, namely a theory of of objects in spacetime whose localization is string- instead of point-like. The result is corroborated by the failure of the conformal embedding view: whereas the "target space" of the chiral theory (higher dimensional vector or spinor indices of currents) becomes string theories spacetime, the one-dimensional source space does not describe a string embedded in the target spacetime but rather enriches the "inner" space over each point (spin, masses). Hence string theory solves a problem which enjoyed some popularity in the 60s namely the construction of infinite component fields.